CA2206301A1 - Damped laminates with improved fastener force retention, a method of making, and novel tools useful in making - Google Patents

Abstract

The present invention relates to a vibration damped laminate article having improved force (torque and/or pressure and/or stress) retention, a method of making one article type and novel tools used to make the one article type. The first laminate comprises at least one layer of damping material (88) between at least two substrate layers (86, 90). At least one deformation area (84) is present in the laminate wherein the substrate(s) are plastically deformed such that they are closer than non-deformed areas of the substrate and wherein the damping material has less mass than in a non-deformed area of the article; the deformation areas providing the areas of good force retention, for an attachment device (82) attached thereto. The second laminate, which is not deformed, contains an additive of sufficient modulus, diameter and loading, in a vibration damping layer to provide improved force retention.

Description

CA 02206301 1997-0~-28 wo 96/21560 Pcrruss5/l627 DAMPED LAMINATES WITH IMPROVED FASTENER
FORCE RETENTION, A METHOD OF MAKING, AND NOVEL TOOLS USEFUL IN MAKING
Field of the Invention The present invention relates to a vibration damped l~min~te article having improved force (torque and/or pressure and/or stress) retention, a method of making the article, a f~ctçning assembly, and novel tools which can be used to make thearticles. An atta~hm~nt device, such as a screw, that provides a merh~nical force to hold the l~min~te article of the invention in a location has improved torque and/or pressure and/or force retention colllpal ed to systems using known l~min~tes. The present invention also relates to a method of improving the force retention properties of a damped l~min~te article by pe-.llanel.l displ~cçm~nt of at least a portion of the vibration damping material in an intçn.1ed ~tt~chmçnt location from an initial location which in turn reduces the force lost following ~ttachm~nt of the l~min~te with an attachmçnt device (such as a screw, bolt, etc.).

Back~round of the Invention Periodic or random vibrations or shocks can excite the resonant frequencies in various structures, such as disk drive covers, disk drive bases, automobile oil pans, valve covers, etc., which can be problematic due to the res--lt~nt formation of undesirable stresses, displ~cç,~ , fatigue, and even sound radiation or high levels of sound tr~n.cmi~sion. In addition, these various components (disk drive covers, automobile valve covers, etc.) may also be used as part of an enclosure to prevent acoustical noise from ~ , through the enclosure and are designecl to reduce the level of noise passing through. Such undesirable vibrations, shocks or noisesources are typically intlllced by external or internal forces or noise generators and can be experienced by a wide variety of articles and under a variety of conditions. For example, resonant vibrations can cause significant levels of acoustical noise in a disk drive assembly. This noise can be easily tr~n~mittable through a typical monolithic material cover or base casting of the disk drive allowing excessive noise to pass CA 02206301 1997-0~-28 WO 96/21560 PCT/I~S95/16271 through the material which is undesirable to the operator of the disk drive. Theresonall~ vibrations in the cover or base may also lead to excessive vertical orhorizontal displacement of the key m~cl~ ical ~tt~çhment points in the disk drive, leading to poor overall disk drive performance and even potential reliability problems.
S Control of the resonant vibrations and shock in a disk drive are key to optimum pelrollll~ce in the read/write process and quiet operation plus high disk drive reliability.
Various techniques have been used to reduce reson~ll vibrational and shock effects (stresses, displ~cemPnt~7 noise, etc.) on articles such as disk drive storage articles and other designs requiring control of resona,ll vibrations and noise generation or tr~n~mi~ion. Three basic techniques to reduce vibration and shock effects, plus noise control in the basic design of a structure include: 1) adding stiffilPss or mass to the article so that the resonant frequencies of the article are not excited by a given excitation source. Noise tr~n~mi~sion may also be reduced with the added mass or stiffnes~; 2) isolating the article from the excitation so the vibrational or shock energy does not excite the article's resonant frequencies; and 3) rl~mping the article so that given excitations do not result in excessive negative effects at the resonant frequencies of the article and that noise cannot easily 11 ~Isll~il through the article.
Option 1) above may not be desirable, as the added mass or stiffne.ss can add significant weight or volume to a design. Added mass is not desirable for weight-sensitive applications (automobiles, disk drives, planes, etc.) and added stiffness can add cost and/or thic~nPss to an article, which may be undesirable. Isolating the article as in option 2) may not be desirable from a design, cost, weight, etc., standpoint.
The pl er~ ed known method to reduce resonant vibrations, shock effects and noise tr~n~mi~.sion or generation is by using viscoelastic damping materials in a design. The viscoelastic damping materials will dissipate the vibrational energygenerated by the reson~l vibrations, thus reduc.in~ the negative effects of the excitation source. The viscoelastic materials when used in a design can also reduce the tr~n~mitted or generated noise in an article. The viscoelastic materials can be used CA 02206301 1997-0~-28 W O 96/21560 PCTrUS95/16271 as an add-on item to the article or more optimally as an inner layer of a l~min~te structure used to make the article.
Patents that describe dalllping and isolation methods to control the resonant vibrations in various articles to reduce noise generation, noise trancmiccion, S mechanical displacements, etc. (such as automobiles oil pans, valve covers, l~min~ted panels, disk drive covers, etc.), include U.S. Patent No. 5,258,972 "Magnetic Damping Disc for Improved CD Player Pl lr~ ance," issued November 2, 1993 (Brasfield et al.) and U.S. Patent No. 4,223,073 "High Temperature Damping Composite" issued September 16, 1980 (Caldwell et al.).
Two types of surface or external damping tre~tnnçntc which can be used to reduce shock or vibration impact on various articles are (1) free layer damping tre~tmçnts; and (2) con~ll~lled layer damping trç~tm~nts. Both ofthese damping tre~tm~nts can provide high levels of d~-~.p;ng to a structure, i.e., dic.cip~tion of undesirable vibrations, without sacrificing the stiffnçss of the structure. The use of 15 viscoelastic materials as exterior surface damping ~ ..e~lc is described in EP
0507515, published October 7, 1992. Examples of additional surface or external d~ll~ing techniques are described, for example, in U.S. Pat. Nos. 2,819,032 (issued January 7, 1953); 3,071,217 (issued January 1, 1963); 3,078,969 (issued February26, 1963); 3,159,249 (issuedDecell,bel 1, 1964); and 3,160,549 (issuedDecember 8, 20 1964). These patents describe methods of ~tt~k",~"l.c of dampers to a surface. A
more p,e~elled configuration in~ludes an inner and outer layer of high modulus material (substrate layers) and an inner layer(s) of a viscoelastic material. The use of this configuration can simplify the m~nllf~ctllring process and design, but also adds the potential for problems in ~tt~çhm~.nt of the "viscoelastic l~min~te article" to 25 various bases, housings, or other structures. Patents that describe this technique include: U.S. Patent Nos. 4,678,707 (issued July 7, 1987); 4,681,816 (issued July 21, 1987); and 4,048,366 (issued September 13, 1977).
Con~l~,ed layer damping tre~tnl~ntc or viscoelastic l~min~te damping is also referred to as "shear damping" l~ e~ ntc In this technique, cl~mring occurs by 30 applying a damper concicting of one or more layers of viscoelastic damping material CA 02206301 1997-0~-28 W O96/21560 PCTrUS95/1627 and one or more layers of a higher tensile modulus material (substrate) to one or more exterior surfaces of the article to be damped or by combillil g the layers of higher modulus material (substrate) and viscoelastic damping materials in a "sandwich construction" or "l~min~te" from which the end article is made.
Energy dissipates from the viscoelastic damping material via a shear strain mer.h~nicm The shear strain results from constraints by the higher modulus consL,~"~ing layer and the base structure or between the layers of the l~min~teddamping structure.
Both co~lsL~ ed layer damping lle~ -c~-ls and viscoelastic l~min~te damping techniques can be used for identical applications. The viscoelastic l~min~te is advantageous over the constrained layer add-on tre~tmrnt in that it reduces the overall parts count in an assembly thus reduçing potential m~nllf~chlring costs while providing the possibility of a more optimum damping design.
One of the largest uses of viscoelastic l~min~tes is in the automobile industry for oil pans, valve covers, and other viscoelastic l~min~te formed parts or panels. The l~min~tes in this application offer significant reductions in the acoustical noise tr~n.cmi.c.~ion and genc,~lion escapi"g from the engine and also reduce the acoustical noise that can enter the p~csrnger co",pa, ~mc~ in addition to red~çin~ the resonant frequency amplitudes in the articles. These l~min~tes typically have an ~tt~çhm~nt area by which the l~minate part is ~tt~ched to a base, housing or other structure. The method of ~tt~çhm~nt of the l~min~tec could be by screws, bolts, nails, rivets, clamps, or other meçh~nical ~tt~çhm~nt devices.
One potential problematic area in using the viscoelastic l~min~tes is in the ~tt~çhm-ont of the l~min~tes The viscoelastic darnping material will stress relax following att~çhm~nt of the l~min~te(s) to the structure or base using the screws, bolts, nails, rivets, clamps or other mechanical ~tt~çhm~nt devices. The ~tt~çhm~nt devices are used to securely hold the l~min~tes in a specific alignmrnt and under a specific stress or pressure or torque or f~ct~ning force. The torque, pressure, stress, or f~ct~ning force will tend to relax somewhat normally even in non-l~min~te structures due to stress relaxation in the fastener material, substrate material, or CA 02206301 1997-0=,-2X

fastener ~tt?rhment point to the structure. Thus, in a l~min~ted article, stressrelaxation occurs in the f~ctening system, the l~min~te, and also to a smaller degree, the higher modulus layers of the l~min~te. The doll~indnt area of stress relaxation is typlcally the viscoelastic material part of the l~min~te. Furthermore, variations in S telllpel~ re above the application telllpeld~ure ofthe l~min~te using the ?~tt~rhmrnt devices can allow the ~tt~chm~nt system to stress relax in a shorter period of time.
The stress, torque, pressure, or f~trtling force in the ~tt~çhmrrlt device prevents the ~tt~chm~ont device from loosening during use of the structure the l~min~te is attached to. If the att?r.hmrrlt device is allowed to fall below a critical 10 ~ttachment force, the l~min~te could become loose, allowing the l~min~te to shift from the desired location. The loose l~min~te could h~lel~e with other items near it and/or induce mi~lignmrnt in items attached to the l~min~te. Furthermore, the fastener devices could loosen to the point where they would no longer support the l~min~te in a proper ~ nment~ leading to a catastrophic failure of the unit to which 15 the l~min~te is ~ttarhecl Methods that have been used to prevent failure of the ~tt~çhmerlt of the l~min~te due to the stress relaxation in the viscoelastic layer are ~ cucsed below.
Each method has shortfalls that can add cost, processing time, design complexity, etc., or colllbillations of each that are not desirable. Operations or designs to reduce 20 the viscoelastic layers' stress relaxation after application of the fastener device include those which are disclosed in PCX-9 POLYCORE COMPOSITES~ Physical Properties Sheet, Pre Finish Metals Inc., Polycore Composites~, Elk Grove Village, Illinois, such as:
1) The use of an automatic Bolt Torque equipment should allow for the entire 25 l~min~te construction. This fastener ~tt~rhmpnt method provides for an increased att~rhment force (torque or pressure) (as colllpaled to a non-l~min~te material) via the ~tt~chm~nt device to the l~min~te in the ~tt~rhmrnt area such that after thedamping material layer stress relaxes the minimllm force required for the application is I~A~ h~ed This added application force to the ~ltachment device to achieve an30 initial force value high enough not to stress relax below the minimllm specification CA 02206301 1997-0~-28 W O 96/21560 PCTrUS95/16271 requires an atta~hm~nt device that can support the added force used on it without mechanical failure. For example, in a disk drive cover application, ~ mimlm screws may be used to attach a l~min~te cover to a base. The base casting has holes prepared to accept the screws. The screws and screw heads are dç.~igned for low cost and a 5 monolithic cover (i.e., no torque loss in the screw ~tt~hmPnt device due to stress relaxation in the damping material). The increased torque required initially when att~.hin~ the cover to achieve the minimllm torque in the screw following stressrelaxation can exceed the strength of the screw head-shaft interface, the screw head features (Phillips, Torx, slotted, etc.) that the driver uses to engage the screw and 10 through which the force is applied. In addition, the screw hole tapping or screw features can be stripped in the base or col-lbina~ions thereof.
To allow for added torque to the f~tP.nin~ system without failure, a stronger screw must be used (such as a stainless steel screw) or a stronger tapped hole for the screw in the base the screws fit into. This added torque requirement in the screw (or 15 . ~tt~chm~nt device) can significantly increase the screw cost or the tapped hole cost, plus add cost to the screw att~r.hm~nt equipment to ensure a tightly controlled att~chm~nt process.

2) Another method involves use of a thin input viscoelastic layer in the construction of the l~min~te to lessen the amount the viscoelastic layer can stress relax. (PCX-9 discloses a layer which is only 0.0254 mm (.001 ") thick.) This approach is undesirable, as the optimum design of the l~min~te viscoelastic thickness to reduce resonant vibrations (and reduce acoustical noise generated or tr~n~mi.~ion) may not be the optimum for the viscoelastic layer thickness in regard to force retention after viscoelastic relaxation. In addition, in applications where the l~min~te material is formed into a specific shape (drawn, embossed, etc.), a too-thin viscoelastic layer could reduce the pelrollllance ofthe l~min~te in regard to its ability to be drawn to a specific depth or length without del~ on of the viscoelastic layer occurring.

3) Another method involves re-torquing or applying a secondary (or more) re-application of ~tt~chment force once the viscoelastic layer has stress relaxed to achieve the desired ~tt~chm~nt force. This method is disadvantageous in that it adds cost to the attachment process and is not acceptable in most applications, especially high-volume applications where added work in process or secondary operations cansignificantly increase m~nllf~ct~lring costs. The time to m~mlf~lre an assembly using a l~min~te could also increase significantly if the "time to stress relax" is long.
In addition, process steps following the att~çhment of the l~min~te to another item or other components added to the assembly the l~min~te is a part of, or to the l~min~te, could prevent the re-torquing of the att~hmçnt devices if they are hidden or covered or too near other components when installed. The re-torquing could also alter ~ nment of the l~min~te slightly, which in some applications may be undesirable if other processes are completed that were based on the l~min~te's initial location.

4) Another method involves the application of heat to the l~min~te during the ~ttachment device application process. The heat will reduce the modulus of the viscoelastic layer, thus making the viscoelastic layer softer and may be easier to co,l-press. When the force of the fastener device is in.ct~lle(l, the viscoelastic layer will tend to stress relax during application of the fastener device and not over a longer period of time. If the temperature is high enough, a signific~nt portion of the stress relaxation in the viscoelastic layer may occur during the fastener device application.
This method to reduce stress relaxation is disadvantageous in that the use of heat during the l~min~te article attachm~ont is often not practical for a m~mlf~ctllring process, as it will add cost, application complexity, safety concerns if the temperature required is high, and ~liffiC -lty in monitoring the process. In addition, components, fluids or electronics near the l~min~te may not allow for the use of heat in theapplication of the l~min~te 5) Another method involves co"")le~ion ofthe viscoelastic layer around the area to be torqued during ~ g of the l~min~te This method of co""~ression may not provide adequate torque retention in all applications. Although simple co",pless;on of a viscoelastic damping material may provide some force retentionimprovement, optimum force retention will not be achieved, especially in applications CA 02206301 1997-0~-28 WO 96t21560 PCT/US95/16271 where only low torque and/or force and/or pressure can be applied in ~tt~chmçnt of the fastener device.
Thus, in applications where the above methods are not acceptable, a new method is required to attach the l~min~te and still achieve acceptable force retention 5 characteristics.

Summarv of the Invention We have found such an alternative approach. The present invention provides a damped l~min~te article having at least one intPnded ~tt~çllmPnt area on the 10 l~min~te wherein the vibration damping material layer is less massive or non~xi~tPnt and one or more substrate layers are plastically deformed. Since the damping material is typically reduced or nonexistent only in the intended ~tt~çilmP.nt area(s) this allows a l~min~te to be optimally designed for the application in terms of vibration damping material thickness for control of resonant vibration or shock and also noise 15 generation or tr~n~mi~sion, plus forming requirements the l~min~te may need to meet.
The ~tt~chm~nt area(s) provide improved torque and/or stress and/or force and/orpressure retention in these ~tt~c~ment area(s) upon application to a second article which may be a base, housing, etc., with the ~tt~çhmPnt device. Since the vibration damping layer is less massive or nonPYi~tPnt only in a very small area this does not 20 affect the overall design or effectiveness of the viscoelastic damping l~min~te P,-I~
The present invention provides a l~min~te article comprising:
a first substrate layer and a second substrate layer;
at least one layer of vibration damping material comprising a viscoelastic~5 material positioned between said first and second substrate layers;
optionally one or more additional substrate layers positioned between said first and second substrate layers;
optionally 1 or more bonding material layers bonded between a substrate layer and a vibration damping layer, wherein the storage modulus of each bonding material CA 02206301 1997-0~-28 WO 96/21560 PCI'/US95116271 layer is higher than the storage modulus of the viscoelastic material conla;ned in a vibration damping layer to which it is bonded;
wherein the storage modulus of each substrate layer is greater than that of the viscoelastic material in any.vibration damping material layer with which it is in contact;
wherein at least one deformation area is present in said article, wherein a d~Ço, I,,alion area is an area of the article wherein at least one substrate layer is plastically deformed such that at least two substrate layers are touching or positioned closer to each other than in an area of the article in which none of the substrates are plastically deformed, and wherein in at least 1 vibration damping material layer, within at least a 5%
area ofthe deÇo""alion area, the vibration damping material is non-exist~?nt or, if present, has a mass that is 90% or less than the average mass of the vibration damping material layer of an equal area in an area of the article which is not in a defol",a~ion area.
The l~min~te article may optionally have one or more holes present in a substrate layer in a d~rul~ Lion area. The l~min~te article may have one or morethrough holes present in the article in a deformation area. A "through hole" as used herein refers to a hole that passes completely through the article.
The present invention also relates to a non-deformed l~min~te in the t~ç~lment area with improved force retention. This l~min~te article comprises:
a first substrate layer and a second substrate layer;
at least one layer of vibration damping material comprising a viscoelastic material positioned between said first and second substrate layers;
optionally one or more additional substrate layers positioned between said first and second substrate layers;
optionally 1 or more bonding material layers bonded between a substrate layer and a vibration damping layer, wherein the storage modulus of each bonding material layer is higher than the storage modulus of the viscoelastic material contained in a 30 vibration dar~ g layer to which it is bonded;

CA 02206301 1997-0~-28 WO 96/21560 PCT/llS95/16271 whel ein the storage modulus of each substrate layer is greater than that of theviscoelastic material in any vibration damping material layer with which it is in contact;
wl~el ein at least one vibration dalllping material layer further comprises an 5 additive selected from the group consisting of fibers, particulates, fillers and mixtures thereof;
wherein the total amount of additive is about 1 to about 95 weight percent based upon the total weight of the vibration damping material;
wherein the particulate size ranges from about 10 to about 125% ofthe average thickness of the vibration damping material layer in which the particulate is present;
wherein the fiber ~ meter ranges from about 10 to about 125% of the average thic1~ness of the vibration damping layer in which the fiber is present;wherein the load bearing capacity ofthe additive is at least about 100 psi The invention also relates to the method by which the l~min~te articles of the invention are made The present invention provides a method of improving the stress and/or torque and/or force and/or pressure retention of a damped l~min~te article by permanent displ~cPmPnt of at least a portion of the vibration damping material(s) and plastic de~....alion ofthe substrate(s) in the int~nded de~..nalion area(s) The present invention provides a method of plepa~ing a l~min~te article comprising the steps of (a) prepa~...g a l~min~te co...~.ising at least one layer of vibration damping material comprising a viscoelastic material positioned between a first substrate layer and a second substrate layer, and optionally one or more additional 25 substrate layers positioned between said first and second substrate layers wherein each substrate layer has a higher storage modulus than the storage modulus of the viscoelastic material contained in a vibration damping material layer with which it is in contact, optionally 1 or more bonding material layers can be bonded between asubstrate layer and a vibration damping layer, wherein the storage modulus of each WO 96/21560 PCI'/US9~7/16271 ~ bonding material layer is higher than the storage modulus of the viscoelastic material contained in a vibration damping layer to which it is bonded;
(b) forming at least one derol.llalion area in the l~min~te article by impinging a punch tool against at least one area of at least one substrate layer5 selected from the group consisting of said first and second substrate layers to plastically deform one or more substrate layers, such that at least two substrate layers are touching or positioned closer to each other than in an area of the article in which none of the substrate layers are plastically deformed, wherein within at least 1vibration damping layer, within at least a 5% area ofthe derollllalion area, the10 vibration damping material is non-.oxi~tçnt or, if present, has a mass that is about 90%
or less than the average mass of.the same vibration damping material layer in an equal area of the article which is not a deformation area.
In addition, the deÇollllalion of the substrate(s) can reduce the contact area between the alt~m~nt device (e.g., the head of a screw, etc.) and the l~min~te 15 surface. The smaller surface area of contact will equate to an overall lower dynamic friction between the screw head and l~min~te substrate surface during the torquing operation, thereby allowing effectively more force to be applied in torquing the screw into place for a given torque applied to the head ofthe screw (i.e., more force available to overcome the friction in the screw threads and the threaded/tapped hole).
The invention also relates to novel tools used to make the articles of the invention. The present invention provides a punch tool comprising a sha~ having an end, wherein said end complises (i) at least one protrusion; and (ii) at least one gripping feature. The gripping features are preferably selected from the group consisting of textured surfaces, continuous ridges, discontinuous ridges, continuous ridges having textured surfaces, and discontinuous ridges having textured surfaces.

Brief Description of the Drawings Fig. 1 is a top view of a disk drive, showing the disk drive cover.
Fig. 2 is a cross-section of the disk drive taken along line 2-2 in Fig. 1.

CA 02206301 1997-0~-28 W O96121560 PCTrUS95116271 Fig. 3A is a partial cross-section of the top of the disk drive taken along line3-3 of Fig. 1.
Fig. 3B is a second embodiment of a partial cross-section of the top of the disk drive taken along line 3-3 of Fig. 1.
Fig. 3C is a third embodiment of a partial cross-section of the top of the disk drive taken along line 3-3 of Fig. 1.
Fig. 3D is a fourth embodiment of a partial cross-section of the top of the diskdrive taken along line 3-3 of Fig. 1.
Fig. 3E is a f~Lh embodiment of a partial cross-section of the top of the disk 10 drive taken along line 3-3 of Fig. 1.
Fig. 4 is a partial cross-section of the top of the disk drive taken along line 4-4Fig. 1.
Fig. 4A is a partial cross-section of the top of the disk drive ~,vith the present invention.
Fig. 5 is a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 6 is a second embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 7 is a third embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 8 is a fourth embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 9 is a fifth embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 10A is a sixth embodiment of a partial cross-section of the top of the diskdrive showing the mounting hole.
Fig. 10B is a seventh embodiment of a partial cross-section of the top of the disk drive sho~,ving the mounting hole.
Fig. 10C is an eighth embodiment of a partial cross-section ofthe top of the disk drive showing the mounting hole.

CA 02206301 1997-0~-28 WO 96nl560 PCT/US95/16271 Fig. 10D is a ninth embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 10E is a tenth embodiment of a partial cross-section of the top of the diskdrive showing the mounting hole.
Fig. 1 OF is a eleventh embodiment of a partial cross-section of the top of the disk drive showing the mounting hole.
Fig. 1 OG is a partial cross-section of the top of the disk drive showing the f~ctçrling area.
Fig. 10H is a second embodiment of a partial cross-section of the top of the disk drive showing the f~et~ning area.
Fig. 1 OI is third embodiment of a partial cross-section of the top of the disk drive showing the f~ctçning area.
Fig. 11 is fourth embodiment of a partial cross-section of the top of the disk drive showing the f~.etçning area.
Fig. 12 is a cross-section of a punch of the invention and a l~min~te having a hole which has not been modified.
Fig. 13-26 are side views of di~l en~ embodiments of punches.
Fig. 27 is a bottom view of a punch.
Fig. 28 is a partial cross-section of a punch taken along lines 28-28 of Fig. 27.
Fig. 28A is a second embodiment of a punch showing venting holes.
Fig. 29-30 are side views of di~e~e"l embodiment of punches with an extension added to the protrusion.
Fig. 31 is a partial cross-section of a punch.
Fig. 32 is a partial cross-section of a punch.
Fig. 33 is a partial cross-section ofthe top ofthe disk drive showing the f~et~ning area.
Fig. 34 is a partial cross-section of the top of the disk drive showing the f~et.o.nin~ area.
Fig. 35 is a partial cross-section ofthe top ofthe disk drive showing the f~et~ninp area.

CA 02206301 1997-0~-28 WO 96/21560 PCI~/US95/16271 Fig. 36 is a partial cross-section of another l~min~te of the invention.

Definition of Terms The term "~tt~hn~Pnt device" as used herein refers to items such as screws, 5 bolts, clamps, nails, rivets, clamps, integrally molded ~tt~çhmPnt devices, and other mechanical att~çllment devices that can hold the l~min~te in a desired location,position, ~ttitude or configuration with a desired level of stress and/or torque and/or pressure and/or force.
The term "~tt~çhmPnt area" as used herein describes the area in which an 10 ~tt~çhment device may contact the l~min~te and impart the force that is used to hold the l~min~te in a position, location, ~ttitudP,7 or configuration.
An example of an "~tt~hmPnt area" would be the area under the head of a screw, for example; the "att~hmP.nt area" being defined to extend through the entire l~min~te.
The term "defoll"alion area" as used herein describes a section ofthe article in which at least one substrate layer has been plastically deformed. The deformation area in~.hldes any article layer areas above and below the plastically deformed substrate areas. The d~fo""alion area is defined such that it does not include through hole areas. Furthermore, the defol",alion area does not include areas above or below 20 a hole, which is not a through hole, in the article. For example, if the upper substrate layer contains a hole, the vibration d~,lpil.g layer beneath the area of the hole and the lower substrate layer in the area beneath the hole are both not considered to be part of the deformation area.
The ~tt~çhmPnt area can be the same, larger or smaller than the deformation 25 area. The defol"~alion area is generally desi ned to be as small as required to meet the needs of the ~tt~çhmPnt device so as to have a minim~l impact on the pelro""ance ofthe l~min~te article in terms of resonant vibration control and noise generation or tr~n~mi~sion.
The term "residual spring effect" and "residual spring force" are used 30 interchangeably herein to refer to the spring type potential resistive force that exist CA 0220630l l997-0~-28 between 2 or more substrate layers of a l~min~te that have a separation between them. This separation will require the attachm~nt force of the ~tt~hm~nt device to overcome the residual spring force during ~tt~cllm~nt device application. Substrate layers that are deformed such that no, or minim~l separation exists between the 5 substrate layers will have no or in~ignificant residual spring force to overcome.
The terms "damped l~min~te" and "l~min~te" are used interchangeably herein to refer to a construction co~p~i~h~g at least two substrate layers and at least one layer of a vibration damping material comprising a viscoelastic material that has a lower storage modulus than the substrate layers it is positioned between.
10The substrate layers for a typical article construction include but are not limited to materials such as stainless steel, ~IIlmimlm copper, carbon steel, lead and various other materials which typically have a Young's modulus greater than about 5 X 105psi (34.5 x lo8 Pascals) at the ope~li"g temperature ofthe application (typically about -60 to 600~C). The vibration damping layer has a storage modulus of 15typically less than about 1 x 105psi (6.9 x 108 Pascals) at the te~pe,~ re ofthe application. The l~minate can also be of a multiple layer construction that may have more than two substrate layers and also more than one vibration damping materiallayer. The construction could also have vibration damping layers ~(ljac~nt to each other in layers or stripes or other patterns. The damping layers may also be 20 continuous or discontinuous.
The terms "pl~tic~lly d~ru""ed" and "plastic dt;rol,.,alion" are used herein to describe the permanent change to the l~min~te's shape or profile or contour or features that occurs when the substrate layer(s) are exposed to a force or strain (typically from a punch tool and the tool's working surfaces) that imparts a force into 25 the material that e~cee~1~ its yield modulus.
The term "substrate contact surface" as used herein refers to the surface area(s) of the l~min~te that the attac.hm~nt device comes in contact with upon application and imparts the att~chm~nt device's force upon the l~min~te.

CA 02206301 1997-0~-28 The term "working surfaces" as used herein refers to the surface(s) area(s) of a punch tool that come into physical contact with the l~min~te during the punch tool stamping operation.

5 Detailed Description of the Invention The first step in p. ~pa,illg the article of the invention typically involves plcpaling a damped l~min~te A damped l~min~te is typically plc~,ared by incorporating one or more layers of a vibration damping material into the l~min~te article typically by adding one layer or a plurality of layers of a vibration damping 10 material during the m~nllf~ctllre ofthe article as an inner layer(s). The layer(s) may be continuous or discontinuous. The discontinuous layer may be separated by space(s) and/or a nondamping material. A continuous layer may comprise the same damping material or di~erent damping materials ~dj~c~nt to each other, thereby forming a continuous surface.
Vibration Dampin~ Material The vibration damping material inçll-des a viscoelastic material or co~lbilla~ion of dirrertnt viscoelastic materials. Useful viscoelastic materials are those having a storage modulus of at least about 1.0 psi (6.9 x 103 Pascals) and a loss 20 factor of at least about 0.01, at the temperature and frequency of use.
Advantageously and pre~e~bly, a layer(s) ofthe vibration damping material is placed in areas of high strain energy as an inner layer(s) to provide improved damping in the desired frequency and te--~llcl ~LIlre range. The added damping layer(s) should increase the vibrational damping, as measured by the system loss factor, of the article 25 or the structural material of which it is made, by at least about 10 percent in at least one vibrational mode as co...parcd to a non-l~min~te construction. System loss factor is a measure of the damping in a structure.
A viscoelastic material is one that is viscous, and therefore capable of ;p~l;"~ energy, yet exhibits certain elastic properties, and therefore capable of 30 storing energy. That is, a viscoelastic material is an elastomeric material typically CA 02206301 1997-0~-28 W O96/21560 PCTrUS95/16271 co.~ long-chain molecules that can convert mechAnical energy into heat when they are deformed. Such a material typically can be deformed, e.g., stretched, by an applied load and gradually regain its original shape, e.g., contract, sometime after the load has been removed.
Suitable viscoelastic materials for use in the vibration d~mpin~ materials of the present invention have a storage modulus, i.e., measure of the energy storedduring d~Ç~ alion, of at least about 1.0 psi (6.9 x 103 Pascals) at the frequency and temperature of operation. The storage modulus of useful viscoelastic materials can be as high as 500,000 psi (3.45 x 109 Pascals); however, typically it is about 10-2000 psi (6.9 x 104 - 1.4 x 107 Pascals).
Suitable viscoelastic materials for use in the vibration damping materials of the present invention have a loss factor, i.e., the ratio of energy loss to energy stored, of at least about 0.01. Pl efel~bly the loss factor is at least about 0.1, more preferably about 0.5-10, and most p~ ably about 1-10, in the frequency and temperature 15 . range where damping is required (typically about 1-10,000 Hz and -40 to 600~C or more.) This loss factor is a measure of the material's ability to (li~ir~te energy and depends on the frequency and temperature experienced by the damping material. For example, for a cros~lin' e(l acrylic polymer, at a frequency of 100 Hz, the loss factor at 68~F (20~C) is about 1.0, while at 158~F (70~C) the loss factor is about 0.7.P~ ~re" ed viscoelastic materials are those that remain functional over a wide range of temperatures, e.g., about -40~C to about 300~C. Most prere"ed viscoelastic materials are those that cover the broadest telll~c;l~L-Ire and frequency range at the desired minimllm loss factor and storage modulus to achieve acceptable damping of the viscoelastic lAmin~te article, and do not experience a significant degradation in properties due to long times at high ~enl~el aLLlres or short excursions beyond these high temperature levels.
Useful viscoelastic damping materials can be isotropic as well as anisotropic materials, particularly with respect to its elastic p[op~, ~ies. As used herein, an "anisotropic material" or "nonisotropic material" is one in which the properties are dependent upon the direction of measurement. Suitable viscoelastic materials include CA 02206301 1997-0~-28 ~ urethane rubbers, silicone rubbers, nitrile rubbers, butyl rubbers, acrylic rubbers, natural rubbers, styrene-butadiene rubbers, and the like. Other useful damping viscoelastic materials include polyesters, polyureth~n~s, polyamides, ethylene-vinyl acetate copolymers, polyvi~yl butyral, polyvinyl butyral-polyvinyl acetate 5 copolymers, epoxy-acrylate interpenel~ling n~lwo,ks and the like. Specific examples of useful materials are disclosed or referenced in U.S. Pat. No. 5,183,863 (issued February 2, 1993), U.S. Pat. No. 5,262,232 (issued November 16, 1993) and U.S.
Pat. No. 5,308,887 (issued May 3, 1994).
Examples of thermoplastic materials suitable for use as the vibration damping 10 material in viscoelastic l~min~te articles according to the present invention include, but are not limited to, those selected from the group consisting of polyacrylates, polycarbonates, polyetherimides, polyesters, polysulfones, polystyrenes, acrylonitrile-butadiene-styrene block copolymers, polypropylenes, acetal polymers, polyamides,polyvinyl chlorides, polyethylenes, polyureth~nes, and co",bil,alions thereof.
Useful viscoelastic materials can also be crosslinkable to enh~nce their strength and/or temperature resistance. Such viscoelastics are classified as thermosetting resins. When the viscoelastic material is a thermosetting resin, then prior to the m~mlf~ct~re of the viscoelastic l~min~te article the thermosetting resin is in a thermoplastic state. During the m~n~lf~ctllring process, the thermosetting resin is 20 cured and/or crosslinked typically to a solid state, although it could be a gel upon curing as long as the cured material possesses the viscoelastic properties described above. Depending upon the particular thermosetting resin employed, the thermosetting resin can include a curing agent, e.g., catalyst, which when exposed to an app,.,p,iate energy source (such as thermal energy), the curing agent initi~tes the 25 polymerization ofthe thermosetting resin. Particularly ple~lled viscoelastic damping materials are those based on acrylates.
In general, any suitable viscoelastic material can be used. The choice of viscoelastic material for a particular set of conditions, e.g., te".pe~al~lre and frequency of vibration, etc., is within the knowledge of one of skill in the art of CA 02206301 1997-0'7-28 viscoelastic damping. It is to be understood that blends of any of the foregoingmaterials can also be used.

Vibration Dampin~ Material Additives The vibration damping material of the present invention may further comprise an effective amount of a metal, fiberglass, glass, ceramic, and/or organic (such as polyesters, polyamides, epoxy resins, etc.) fibrous and/or particulate material.Optionally, the fibrous and/or particulate material can be thermally conductive,electrically conductive, or both. Herein, an "effective amount" of a fibrous material and/or particulate is an amount sufficient to impart at least improvement in desirable characteristics to the viscoelastic material, but not so much as to give rise to any ~ignific~nt d~l-imelllal effect on the structural integrity ofthe article in which the viscoelastic material is incorporated. Generally, the fibrous or particulate material is used in an amount effective to increase the strain energy ratio of a component 15 co~ il-g the same amount and type of viscoelastic material without the fibrous or particulate material. Generally, an increase in the strain energy ratio of a factor of at least about two in at least one vibrational mode is desired. Typically, the amount of the fibrous material in the viscoelastic material is within a range of about 3-60 wt.
percent, preferably about 10-50 wt. percent, more preferably about 15-45 wt.
percent, and most preferably about 20-40 wt. percent, based on the total weight of the vibration damping material. Typically, the amount of the particulate material in the viscoelastic material is within a range of about 0.5-70 wt. percent, preferably about 1-45 wt. percent, more preferably about 5-40 wt. percent, and most preferably about 5-30 wt. percent, based on the total weight of the vibration damping material.
Fibrous Material Additives The ~olelll~;lllioned fibrous material can be in the form of fibrous strands or in the form of a fiber mat or web, although fibrous strands are pre~ d. The fibrous strands can be in the form of threads, cords, yarns, fii~m~nts~ etc., as long as the viscoelastic material can wet the surface of the material. They can be dispersed CA 02206301 1997-0~-28 wo 96nlS60 PCT/US95/16271 randomly or uniformly in a specified order. Preferably, the fibrous strands, i.e., fibers or fine threadlike pieces, have an aspect ratio of at least about 2: l, and morepreferably an aspect ratio within a range of about 2:1 to about 10:1. The aspect ratio of a fiber is the ratio of the longer dimension of the fiber to the shorter dimension.
Examples of useful fibrous materials in all applications of the present invention include but are not limited to nonmetallic fibrous materials, such as fiberglass, glass, carbon, minerals, synthetic or natural heat resistant organic materials, ceramicmaterials, and the like and met~llic fibrous materials such as steel, st~inless steel, copper, ~ mimlm, gold, silver, lead, tit~nillm~ and their alloys and the like. Generally, high Young' s modulus fibrous materials, i.e., those having a modulus of at least about 100,000 psi (6.9 x 108 Pascals), are prer~l,ed.
Useful natural organic fibrous materials incl~ldP" but are not limited to, thoseselected from the group consisting of wool, silk, cotton, and cellulose. Examples of useful synthetic organic fibrous materials inrl.lde, but are not limited to, those selected from the group consisting of polyvinyl alcohol, nylon, polyester, rayon, polyamide, acrylic, polyolefin, aramid, and phenol. The p,e~"ed organic fibrous material for applications of the present invention is aramid fibrous material. Such a material is collllllc;. cially available from DuPont Co., Wilmin~on, Delaware under the trade names of"Kevlar" and "Nomex."
Generally, any ceramic fibrous material is useful in applications of the presentinvention. An example of a ceramic fibrous material suitable for the present invention is NEXTELTM which is colllll,erc;ally available from Minnesota Mining and M~nllf~ctllring Company, St. Paul, Minnesota. E~llples of useful, commercially available, glass fibrous material are those available from PPG Industries, Inc.
Pittsburgh, Pennsylvania, under the product name E-glass bobbin yarn; Owens Corning, Toledo, Ohio, under the product name "Fiberglass" continuous fil~mPnt yarn; and Manville Corporation, Toledo, Ohio, under the product name "Star Rov 502" fiberglass roving.
Advantages can be obtained through use of fibrous materials of a length as short as about 100 micrometers. The fibers are not limited in length but much longer CA 02206301 1997-0~-28 fibers may provide insufflcient fiber interface and therefore decreased shearingsurfaces between fibers. The fiber thickness or (li~meter for typical fibrous material ranges from about at least 5 micrometers. The thinner the fiber, the higher the surface area of the fibrous material for a given amount of fiber loading. Thus, prerel I ed fibrous materials are very thin. The thickness of the fiber is also dependent upon the desired thickness of the overall damping material layer that will be used in the article.
Thus, many common fibers may not be suitable if the overall damping material thic~ness is relatively thin (e.g., 4-10 micrometers).

Particulate Material Additives The vibration damping material may also include an effective amount of one of the previously indicated particulate materials. The vibration damping material may include an amount of particulate material effective to improve vibrational damping of the article or the structural material of which the article is made by a factor of at least about two in strain energy ratio of at least one vibrational mode. Typically, this would require incorporating about 0.5 to 70 weight percent ofthe particulate material into the vibration damping material, based on the total weight of the vibration damping material. Col"binalions of particulate and fibrous materials may be used, typically about 0.5 to about 70 wt. percent based on the total damping material.
The previously mentioned particulate material(s) useful in the invention can be in the form of bubbles or beads, flakes, or powder, as long as the viscoelastic can wet the surface of the material. ~I t;rerably, the particulate material is on the size order of about 0.1 to about 5 miclo,l,.;~e, ~ and more p, ere~ ~bly about 0.1 to about 2 micrometers.
Examples of useful particulate materials in applications of the present invention include metal, coated or uncoated glass and ceramic bubbles or beads, powers such as silica, ~h~mimlm oxide powder and ~hlminl~m nitride power; cured epoxy nodules, and the like, i.e., those having a modulus of at least about lO,000 psi (6.9 x 107 Pascals), are p~ lled. More preferably, useful particulate materials have a Young's modulus of about 50,000 psi (3.45 x 108 Pascals), and most preferable are CA 02206301 1997-0~-28 those with a modulus of at least 100,000 psi (6.9 x 108 Pascals). Blends of a particulate material and fibrous material can be used from about 0.5 wt. percent to about 70 wt. percent based on the weight % of damping material.
An additional potential benefit of using the previously mentioned fibers and/or particulates in the l~min~te is that the fibers and particulate may reduce the degree of plastic dèro~ lion in the defollllalion area required to perm~n~ntly displace sufficient damping material to improve the stress, force, torque or pressure retention in the ~tt~çhment device. The fibers and/or partic.-l~tes may provide a high modulus meçh~nical force connection through the damping material and to the substrate layers, in effect, bypassing or bridging the damping material and creating a mechanical comle-ilion that can support the ~tt~cllm~nt device's force with stress relaxation less than that of the damping material. When a fastener device is applied, the force between subsLIale layers can pass through the particulates and/or fibers that connect both substrate surfaces to provide reduced damping viscoelastic stress relaxation. The fibers and/or particulate can be used in an amount to optimize fastener device force retention, but not to reduce the damped articles' effectiveness as a damping system. Those skilled in the art would be able to select a proper balance for a given application. Those skilled in the art can also select the fibers, particulates and fillers herein disclosed that can support the att~c~m~nt devices att~çhment force without mer~l~nical failure. The total amount of such particles and/or fibers for this purpose typically ranges from about 1 to about 90%, preferably about 20 to about90%, and most prerel~bly about 50 to about 90%, based on the total weight of thevibration damping material. The fiber rli~TnetPrs for fibers for such a purpose typically ranges from about 0.02 to about 125%, preferably about 10 to about 100%, and most plerel~bly about 50 to about 100%, based on the average thickness ofthe vibration rl~mping layer in which the fibers are contained in a non-defollllalion area. The particle size for particles for such purpose typically ranges from about 0.02 to about 125%, prerel~bly about 10 to about 100%, and most preferably about 50 to about 100%, based on the thickness ofthe vibration d~llpil.g layer in a non-defollllalion area.

CA 0220630l l997-0~-28 W O 96/21560 PCTrUS95/16271 Another potential benefit of using fibers and/or particulates of a sufficiently large size and loading in the l~min~te is that the fibers and particulate may el;",i~ e the need for plastic derolll,alion ofthe l~min~te required to perm~n~ntly displace sufficient damping material to improve the stress, force, torque or pressure retention in the att~1 mPnt device. The fibers and/or partiC~ tes will provide a high modulus mech~nical force connection through the damping material and between the substrate layers, in effect, completely or partially bypassing or bridging the damping material and creating a mechanical connection that can support the ~ttaçhmPnt device' s force and/or stress, and/or pressure, with the stress relaxation less than that of the damping material. When a fastener device is applied, the force between substrate layers can pass through the particulates and/or fibers that connect both substrate surfaces to provide reduced stress relaxation as the damping material is bypassed. The fibers and/or particulate can be used in an amount to opli",i~e fastener device force retention. Depending on size and loading used, the damped articles' effectiveness as a damping system may be reduced somewhat. Those skilled in the art would be able to select a proper balance for a given application. Those skilled in the art can also select the fibers, particulates and fillers that can support the att~chmPnt devices ~tt~çhment force without mechanical failure (such as crushing, etc.). The useful modulus of the fibers or particulates is greater than 100 psi, ,~)rtrel~bly greater than 1000 psi, and most preferably greater than 10,000 psi and in a solid or hollow design that cansupport the f~t~nPr force. The total amount of such particles and/or fibers for this purpose typically ranges from about 10 to about 90%, preferably about 20 to about 90%, and most preferably about 50 to about 90%, based on the total weight of thevibration damping material. The fiber ~ meters for fibers for such a purpose typically ranges from about 10 to about 125%, preferably about 20 to about 125%, and most p~ere,~bly about 50 to about 125%, based on the average thickness ofthe vibration damping layer in which the fibers are contained in a non-der~""a~ion area. The particle size for particles for such purpose typically ranges from about 10 to about 125%, pl~rerably about 20 to about 125%, and most preferably about 50 to about - - -CA 02206301 1997-0~-28 WO 96/21560 PCT~US95/16271 125%, based on the average thickness of the vibration damping layer in which it is contained in a non-defo~ ion area.
In addition, the particulate and/or fibrous material can improve the thermal and/or electrical conductivity between the substrate and/or bonding layers that the 5 damping material layq with the added fibrous and/or particulate material has been positioned between; as coulpal ed to the same damping material layer with no added particulates and/or fibers.
The benefit of adding the thermally conductive fibers and/or particles can be better understood by the following example.
50% by weight ~Illmimlm oxide (A12~3) was added to a damping polymer mixture. The damping polymer is an acrylate. The mixture is coated and cured to a thickness of .100". The thermally conductive damping material was then positioned between two substrate (steel) layers. In addition, a second sarne damping polymer mixture was coated with no added fibers and/or particulates that had a higher thermal conductivity than of the polymer mixture. The second mixture was then positionedbel~e~l two substrate layers as used for the thermally conductive damping material.
Using a thermal resiet~nce test, the flow of heat through the two constructions was colllpa,ed. The thermal resistance test on the test sample using a damping material with no added fiber and/or particulates had a thermal conductivity of .186 watts/m~C. The thermally conductive damping material sample had a thermal conductivity of.322 watts/m~C.
The thermally conductive damping materials will tend to have a higher effective modulus than the same d~mr in.~ material with no added thermally conductive particles and/or fibers.
In certain applications that have been de~igned to o,~)lin"~e the damping of a seismic or wind-sway damper (such as in large displ~cemPnt da,l~el ~) or for a l~min~te enclosure, significant amounts of heat may be generated in the damping material layer (large displ~cPtnPnt damper) itself during straining or may be entrapped in an enclosure (such as in disk drive l~min~te cover) that has an associated heat source.

CA 02206301 1997-0~-28 The damping material is not a good conductor of heat; thus, the heat generated in a large displ~ce-mPnt damper may not be dissipated quickly enough so that the added heat into the damping material may significantly shift the temperature of the damping material and shift the loss factor and storage modulus of the damping 5 material and change the pe~ r ,.mallce of the large displ~cem~nt damper. Improved thermal conductivity in the damping material will limit the temperature change in the damping material.
In a damped l~min~te cover of a disk drive, the cover can be a significant path for heat to tli~sir~te from the drive through conduction, convection or radiation. The 10 heat is generated in the drive by motors or circuit board integrated circuit chips, resistors, capacitors, etc.
By adding a thermally conductive damping material in the l~min~te cover, more heat is allowed to flow through the cover. This increased heat flow through the thermally conductive damped l~min~te cover will reduce the te---pe- ~LLIre in the drive.
15 Excessive temperatures in a drive can damage components and reduce drive pe,r~,...al~ce and/or reliability.
For thermally conductive damping materials, the useful loading of the thermally conductive particles and/or fibers in the damping material is from 10-95%, p.t;r~., ed is 20-95% and most plerel~ed 50-95% based on the total weight of thevibration damping material.
Useful articles that contain at least one layer of a thermally conductive damping material layer inch~de, but are not limited to, large disp!~cem~nt damper, constrained layer dampers, l~min~ted pans, l~min~ted covers, l~min~ted -c~ting~,l~min~ted sheets, l~min~ted baffles, and l~min~ted vents.
Useful damping material polymers incl~de, but are not limited to, acrylates, epoxy-acrylates, silicones, acrylate-silicone mixture and cyanate esters.
One skilled in the art can determine the best means to incorporate the vibration d~"ping material into the articles.
In addition, previously di~cussed bonding layers may be incl~ded in a similar fashion in the articles. The bonding adhesive layer thickness should be designed to the CA 02206301 1997-0~-28 W O96t21560 PCTtUS95/16271 minim..m thickness acceptable to 111;1l;l1l;7e any thermal conductivity losses. Bonding layers may also include thermally conductive materials to further minimi7e any thermal conductivity losses.
In addition, the substrate layer of an article can act as a heat sink. The substrate heat sink design could further be designed to maximize the surface area of the constraining layer to increase heat loss due to convection, radiation, or conduction.
In the l~min~te article of the invention which is required not to be deformed, the same substrates, vibration damping materials, additives, articles made therefrom, 10 f~tening and fastened assemblies, test methods, torque retention, etc., applies as does for the deformed articles, except that a deformed area with reduced vibration damping mass is not required. However, the particulates and/or fibers are required as well as particular loadings, sizes, and modllll..~es 15 Other Additives In addition to fibers and particulate material, the vibration damping material can include additives such as fillers (e.g. talc, etc.), colorants, tough~ning agents, fire rt;~al d~Ls, antioxidants, ~nti~t~tic agents, and the like. Sufficient amounts of each of these materials can be used to effect the desired result.
The vibration damping material that provides the significant portion of the damping for a given material layer may also include an effective amount of an epoxy resin (with or without the previously mentioned particulate or fibrous material)dispersed within the damping material. The vibration damping material may include an amount of epoxy resin effective to improve the meçh~nical integrity of the 25 viscoelastic l~min~te article. The epoxy resin material may have damping properties.
An example of a suitable damping material incorporating an epoxy resin is disclosed in U.S. Pat. No. 5,262,232 (issued November 13,1993). Typically, the amount of epoxy resin incorporated into the vibration d&",p,ng material would be about 0.5 to 95 weight percent, more typically about 5 to about 50 weight percent, based on the 30 total weight of the vibration damping material.

CA 02206301 1997-0~-28 Substrate Layers The substrate(s) useful in the article of the invention can be any material thatcan be plastically deformed (such as a plastic or metal). Examples of suitable substrates include but are not limited to those sçlected from the group consisting of 5 st~inles~ steel, al~mimlm, copper, carbon steel, lead, polyethylenes, polyolefins, polycarbonates, polystyrenes, polyimides, polyesters, poly~cet~tes, and vinyl copolymers, poly acetals, phenolics. The substrate layers may optionally be coated with a coating such as paint, etc.

10 Optional T ~min~te Layers The l~min~te article of the invention optionally further comprises additional layer(s) besides the substrate and vibration damping layers. The article may optionally further comprise a bonding material layer(s), for example. The bonding material layer(s) may be bonded between a substrate layer and a vibration damping layer(s), 15 . whel ein the storage modulus of each bonding material layer is higher than that of the vibration damping layer to which it is bonded. Examples of useful binding layersinclude but are not limited to those selected from the group consisting of epoxy resins and cyanoacrylates. Preferably, the storage modulus of the binding material layer is less than that of a substrate to which it is bonded.
Tooling and Method of the Invention The damped l~min~te article of the invention is typically made by a method wherein at least a portion of the vibration damping material is perm~n~.ntly displaced and the substrate layer(s) plastically deformed in the int~nded ~tt~chmçnt area to 25 provide improved force retention of the ~tt~ hmPnt device as colllpared to a l~min~te that does not have the damping material perm~n~ntly displaced and the substrate layers plastically deformed (and does not use a fibrous, particulate or filler çnh~nced damping material to bridge the dalnpi~g material) in the same area. The vibration damping material is usefully permanently displaced when the force retention is at least 30 about 10 percent improved over a nonmodified l~min~tç7 preferably greater than CA 02206301 1997-0~-28 about 20 percent improved, and most prefel~bly greater than about 30 percent improved, and optimally greater than about 35 percent improved, as determined via "T .~min~te Force Retention Test Method for ~ .~min~tes with Through-Holes" set forth herein.
S The damping material is typically perm~nrntly displaced and the substrate layers plastically deformed in the int.on-led fastener area by means of applyingpressure to at least one outer substrate layer surrounding the vibration dampingmaterial layer and forcing the vibration damping material away from the intenrled fastener area. The substrate layers take on a permanent set (plastic defolmalion) from the force or pressure used to displace the vibration damping material thus hindering the vibration damping material from recovering back into the area from which it was displaced and also provides a l~min~te article that may not have a significant residual spring force between the l~min~te substrate layers. The ~tt~çhmrnt device would need to bring together the substrate layers and overcome the residual spring force that could still exist following the pell,lanenl disp~ m~nt ofthe damping material. If a substrate layer is not sufficiently plastically deformed, it can recover back to a portion of its pre-defollllalion position. This can create a spacing between substrate layers and a residual spring force. When the ~tt~çhm~nt device is ~tt~rhed in this area, this residual spring force can reduce the force retention of the att~çhment device as the initial force used to apply the ~tt~c.hmrnt device is used to overcome the residual spring force in the substrate layers versus a force being used to overcome frictional losses or other mec.h~nical imperlim~nt~ to the fastener device, thuspotentially red~lçin~ the overall force retention once the system stress relaxes. This spacing may also allow a portion of the damping material to recover into this spacing after the st~mring operation. The d~llping material is still pel~"AIlrntly displaced from this area, but with more OpLill~i~ed deformation of the substrate it could be reduced further if the spacing were reduced further.
The punch tools useful according to the invention can be used to concentrate force(s) in a desired localized area to pel...~ne l~ly displace at least a portion of 30 vibration damping material in the inten-led ~tt~çhmPnt area of the damped l~min~te CA 02206301 1997-0~-28 article and to plastically deform at least one substrate layer in such a way as to çlimin~te or m;ni...i7e the amount of elastic recovery of the vibration damping material and also to limit the residual spring force between substrate layers and potentially to feature the substrate surface to ...;n;...;,e dynamic friction during 5 fastener application.
The method of the invention typically involves applying a damping material by coating, spraying or l~---;n; ~ , etc. onto a substrate layer. An opposite substrate layer is applied over the d~,lp;llg material creating a l~min~te material construction.
Additional damping layers and substrate layers can be added. The l~min~te material 10 can be in roll or sheet form. The l~min~te material is then fed or placed into stamping or forming equipment (with associated dies, etc.) to produce an article. In specific reference to the ~tt~çhm~nt areas of the article, and as an example, a damped l~min~te may first have a hole pierced or cut through the entire l~min~te (a through hole) by conventional means such as a standard punch, laser, water jel~l, t;al", etc. to 15 accommodate the ~tt~ m~nt device. The hole can be of a wide variety of shapes. It can be circular, elliptical, square, re~ r, etc. The hole can be symmetrical or a~y"""el,ical. The size ofthe hole will vary depending upon the intçnfled use ofthe article of the invention. Typically the hole will have a ~i~metçr of about 0.005 inches (2 x 10 1 cm) to about 36 inches (91 cm). The hole area can then be subjected to an 20 applied force via a specifically dçsigned punch tool that uses a specific design of a punch to concentrate the punch force to perm~nerltly displace at least a portion of the vibration damping material and pl~tically deform the substrate layer(s) in the int~nded d~rullllalion area. Typically, the location ofthe hole is such that the hole is surrounded by a dero""alion area. The hole may also be partially surrounded by a25 deformation area. Typically the area of each dt;r~"",alion area surrounding or partially surrounding at least one hole is about 0.05 to about 100 times the area of each hole, p,ere,ably about 0.05 to about 10 times the area of each hole.
At least one substrate in the article of the invention may have a variable thic~n~ss in a derolll,alion area. The article ofthe invention may have at least one 30 protrusion in the first and/or second substrate layer. The punch tool is selected such CA 02206301 1997-0~-28 WO 96/21560 PCI~/US95/16271 that the force applied by the tool to the l~min~te substrate(s) is concentrated in the area to be d~rc"l"ed in a manner to perm~nPntly displace at least a portion of the vibration damping material mass from the deformed area. If the tool is not ~esignPd in a fashion to direct the forces in a manner to displace the vibration damping material S in the dero"nalion area, the substrate layer(s) may deform but the vibration damping material layer will not be significantly reduced in mass. The vibration damping niaterial will allow the substrate layers to slip in a manner as to ~;";~ e the punch's effectiveness in perm~nPntly displacing the damping material. If the punch is not clç~igned to ~ 7e slippage of the substrate layers during the stamping process and also to concentrate the forces to displace or extrude the damping material from between the substrate layers, the punch will not be as effective. Known punches typically are not as effective in ~ p!~.ing the damping polymer as punches of the invention as they permit the substrate layers to slip laterally during the stamping process versus being deformed in a manner to significantly displace the damping material and ~ e lateral displ~cçmPnt of the substrate layers.
The punch tool also will impart a feature or d~r~llllalion into the l~min~te by plastically deru"",ng at least one substrate, in addition to displacing at least a portion of the vibration damping material. The outer substrates of the l~min~te may contain protrusions and/or depressions such as ledges, notches, etc.
Design considerations of the punch tool of the invention include the tool' s ability to limit the amount of slippage of the outer substrate layers (the first and second substrate layers) by applying frictional and/or gripping and/or holding forces to the substrate areas and to concentrate the d~r~ll,,alion forces ofthe tool toperm~mP.ntly displace the damping material, deform the substrate layers to minimi7e substrate layer residual spring force and l~;n;.~ P the recovery of the damping material and feature the deformation area to l-~;n;..~;~e the surface area that will contact the f~tPnP.r device and reduce dynamic friction. The reduced slippage of the substrate layers which occurs when using the tool of the invention limits the amount of force not effectively used to reduce the vibration damping mass in the deformation 30 area. When using a known punch tool rather than the one of the invention, the CA 02206301 1997-0~-28 substrate layers may tend to slip on the vibration damping material in a manner that does not allow optimum displ~c~m~nt ofthe vibration ~l~mping material. The slippage can also be de~ al in a stamping operation as the lateral movement of the substrate could distort the substrate layer in an undesirable way and interfere with 5 later operations or part dimensions.
The l~min~te of the invention does not require a hole for ~tt~çhm~nt or as an outlet for the vibration da,llping material to be forced into. In applications where a hole is not desirable or where the area to be used for ~tt~çhm-?nt is not near an edge to provide an outlet for the vibration matenal to be forced to, the tool design is 10 preferably such as to deform the substrate layers to provide a pocket or expansion area for the damping material to be forced into. If an outlet for the viscoelastic is not provided, the substrate layer may have significant deÇulll'alions or features but the dall,l)ing material may not have significant damping material displ~s~m~nt in the d~rullllalion area and thus the force retention may not be significantly improved.
Methods or materials to improve the tool's operation in displacing the vibration damping material and pl~tiç~lly deform the substrate during the stamping operation include but are not limited to the following:
a) ~e~ting the damped l~min~te to lower the modulus of the vibration damping material for the derc ""a~ion of the l~min~te This added heat allows the20 vibration damping material to be more easily displaced (less force needed to displace) as its modulus is lower. Heat applied during ~l~"pil1g is much more desirable, simple and cost effective than using heat during the assembly of the l~min~te article of the invention and a second article with an ~tt~çhm~nt device. Heat can be applied to the l~min~te during or before the deÇ( ,ll,a~ion process step. The heat can be applied using 25 ultraviolet, or infrared heat sources, steam, heated air, ovens, etc., such that the damping material's storage modulus is lowered. The damping material is usefully reduced in modulus if the storage modulus at the derul ",a~ion step is reduced by at least 10%, ple~lably by 25% and most preferably by at least 50%;

CA 02206301 1997-0~-28 b) Using vibration d~.-pil~g materials with little to no cross-linking to reducethe force needed to ~lispl~ce the vibration damping material during the deformation process;
c) Making and using a d~,-ped l~min~te wherein the vibration damping layer 5 initially has less mass in the area(s) to be deformed to reduce the force needed to displace the d~--ping material (This method, however, requires a more co---plc,.process to m~nnf~ctllre the l~min~te article); and d) Using lubricants to reduce the frictional losses in the tool as it deforms the substrate(s) Lubricants will also tend to increase the tool's life The tool used to reduce and/or el; ;n~te the vibration dalllping material will also deform the substrate layer(s) The derol...alion ofthese layer(s) can lead to a hole size reduction as the substrate layer can be pl~qtic~lly deformed to narrow the hole size (Hole size could also be increased) The deÇo....alion process can also lead to slightly raised substrate surfaces or protruding edges caused by the particular tool 15 used to displace the vibration d~..pillg material Knowledge that this will occur is sufficient to design the completed l~min~te article such that desired design criteria can be met, such as for a specific finished hole ~ meter For example, the initial hole diameter can be sPlected to be larger than the desired final hole rli~metpr such that when the dero~.nalion process occurs, the substrate layers are deformed such that the 20 hole f~i~metP~r will decrease due to the plastic dt;ro- ...alion of the substrate layers to yield a final desired article having the desired hole ~i~mP~t~Pr The method ofthe invention can be d~PsignP,d to Ill;~l;lll;~e the displacement of the substrate layer(s) in areas that are not desired if the deroll..a~ion ofthe substrate layer(s) is proble...alic. Options to accon.plish this include but are not limited to the 25 use of secondary tools after the dero....alion process that reform the substrate layers to a more desirable configuration while having a minim~l effect on the force retention of the l~min~te. Secondary tools can enlarge the holes (reaming or drilling) if the initial hole size cannot be sufficiently enlal~ed to be at a final desired hole size following the deÇo----alion operation. The defo.,..alion area can also be fl~ttened by 30 other tools to lower or change the deÇ~,....alion area profile CA 02206301 1997-0~-28 W O 96121~60 PCTrUS95/16271 The present invention can be better understood by refe~ g to Figs. 1-30.
Fig. 1 is a top view of a disk drive showing disk drive cover 6 ~hereill a vibration damping material l~min~te is the cover construction material. The ~tt~bm~nt devices (screws) are indicated by reference numerals 11.
Fig. 2 is a cross-section of the disk drive taken along line 2-2 of Fig 1. The cross-section shows the screws 11 holding the cover 6 in the desired location. This cover 6 uses screw type f~ten~rs 11 that apply an ~tt~.hmPnt force to the cover 6 and the base 9 that the cover 6 is ~tt~Cllecl to via the screws 11. The screws 11 also connect and locate the top cover 6 and the spindle 13 of the disk drive (the unit that rotates the disks so that a read/write head can be located over the data on the disk) and actuator 15 (the unit that moves the read/write head in a horizontal motion across the disks to provide access to di~e~e,.L radii ofthe disk where data is written or stored). For clarity, the disk assembly and read/write heads and arms assembly that extend over the disks have been removed. The cover comprises upper and lower substrate layers 22 and 26, .espe~ ely~ and vibration damping material layer 24.Fig. 3A is a partial cross-section of the disk drive cover 6 taken along line 3-3 of Fig 1. The cross section shows a l~min~te of upper substrate layer 22, lower substrate layer 26, and vibration damping material layer 24 bonded therebetween.Fig. 3B is a second embodiment of a partial cross-section of the disk drive cover taken along line 3-3 of Fig. 1. The cross-section shows the substrate layers 32, 36 and 40 and vibration d~.lj)hlg layers 34 and 38.
Fig. 3C is a third embodiment of a partial cross-section of the disk drive covertaken along line 3-3 of Fig. 1. The cross-section shows the substrate layers 42, 46, 50 and 54, vibration rl~mring layer 48, and bonding material layers 44 and 52 (such as epoxy resins) all bonded together in a l~min~te.
Fig. 3D is a fourth embodiment of a partial cross-section of the disk drive cover taken along line 3-3 of Fig. 1. The cross-section shows the substrate layers 56 and 60, sections of vibration ~mping material 58 and spaces 59 and/or nonvibration damping material therebetween.

CA 02206301 1997-0~-28 Fig. 3E is a fifth embodiment of a partial cross-section of the top of the disk drive taken along line 3-3 of Fig. 1. The cross-section shows the substrate layers 62 and 70, vibration damping material layer 66, and bonding material layers (such as epoxy resins) 64 and 68 all bonded together to form a l~min~te.
Fig. 4 is a partial cross-sectional view of line 4-4 of Fig 1. The cross-sectionshows a l~min~te comprising upper substrate layer 74, lower substrate layer 78, and vibration damping layer 76 and the ~tt~r.hmtont device (screw) 72 securing the l~min~te to the base 80. The l~min~te of Fig. 4 does not have the substrate layer ?4 deformed or the vibration damping layer 76 reduced to have improved force retention characteristics Fig. 4A is a schrm~tic cross-sectional view of line 4-4 of Fig 1. The cross-section shows a l~min~te incorporating a defo,l"alion area ofthe invention comprising upper substrate layer 86, vibration damping layer 88, and lower substrate layer 90 and the att~rhmrnt device (screw) 82 securing the l~min~te to base 92. The l~min~te here does show the vibration damping layer 88 reduced in the defo""aLion area to have improved force retention characteristics. Numeral 84 ~eplese"ls thed~ro",lalion into the top of the upper substrate 86.
Fig. 5 shows a partial cross-section of a l~min~te of the invention comprising upper substrate layer 94, lower substrate layer 98, and damping material layer 96 with a portion of the d~l")ing material 96 displaced so as to provide an improvement in the force retention of the ~tt~çhmrnt device (screw, bolt, nail, rivet, etc.) that might use a pierced hole 100 (the hole can be any geometric shape- round, square, oblong, star, octagon, etc. which the ~tt~rhm.o.nt device can fit through and beapplied) through which the att~chm~.nt device is put to engage the base or othercomponents of the ~tt~rhmPnt device (nuts for a bolt, etc.). The ~tt~chm.ont device is not shown in the cross-section. The cross-section also shows the upper substratelayer 94 deformed, defo",.alion area 103, and deformation 102.
Figs. 6-lOI show other embodiments of partial cross-sections of articles of the invention. Figs. 6-lOI show embodimrnt~ whelein a portion of viscoelastic material is displaced and the substrate is deformed so as to provide an irnprovement in the force CA 02206301 1997-0~-28 retention of the ~tt~hm~nt device with which it is used. The attaçhmçnt device is not shown in the cross-sections. Some f~tçn~r devices use a pierced hole through which the f~t~ner is put to engage the base or other components of the fastener device(nuts for a bolt, etc.). The hole also can be used solely for an area for the damping 5 material to be forced into during the dc;ro~ alion process. An atta~.hm~nt device that does not use the hole can be used in the dero....alion area also (clamp, etc.). The cross-sections also shows the substrate layer(s) deformed. The deformed region of the substrate is typically surrounding the pierced hole area for fastener devices requiring a through hole. The derc,- mi..g can occur on one or both sides of the10 l~min~te and/or in an interior substrate layer(s).
Figs. 5-lOF show the holes that the extension ofthe attaçhment device (shaft of a screw, for example) may have to extend through to engage the base or other components of the attac.hmçnt device. The ~ttaçhm~nt device may also extend around the hole (clamps, etc.) but not pass through it. The hole may serve merely as an area 15 for the damping material to be displaced into during the d~ro-~alion process.The area that has at least a portion of the vibration damping material displaced or removed (dc;ru.-.,alion area) typically extends to an area equal or larger than the attaçhment device contact area with the l~min~te. The attachmçnt devicecould extend outside the der~,....dlion area, but this would not be an optimum use of the invention in terms of achieving the optimum force retention for a given force used to apply the att~chm~nt device. The various dero. Illalion designs of the substrate can be co---bined and otherwise varied. The embodimPnt~ disclosed are not intçnded to limit the invention.
Fig. 6 is a partial cross-section of the article of the invention showing upper substrate layer 104, lower substrate 108, vibration damping layer 106, hole 112,defo.l..alion 110 of the upper substrate 104, and dt;r~,....a~ion area 113.
Fig. 7 is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 114, lower substrate layer 118, vibration damping layer 116, hole 122, deÇo,.llalion 119 ofthe upper substrate 114, and deformation 30 area 121, the d~;rc.-...alion area in an embossed area.

CA 02206301 1997-0~-28 WO 96121560 PCTrUS95/16271 Fig. 8 is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 124, lower substrate layer 128, vibration damping layer 126, hole 132, derull.lalions 130 and 129 ofthe upper substrate 124, and def~llllaLion area 133.
Fig. 9 is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 134, lower substrate layer 138, hole 140, vibration damping layer 136, derolll-alion 139 of the upper substrate layer 134, and dt;Ç~ alion area 137.
Fig. 1 OA is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 142, lower substrate layer 146, hole 150, vibration damping layer 144, d~ro-l--alions 148 and 151 ofthe upper substrate layer 142, and derolllla~ion area 149.
Fig. lOB is a partial cross-section ofthe l~min~te article ofthe invention showing a l~min~te comprising upper substrate layer 152, vibration damping layer154, lower substrate layer 156, hole 168, der~llllalions 160 and 159 ofthe uppersubstrate layer 152, and d~l,l,alion area 161.
Fig. lOC is a partial cross-section ofthe l~min~te article ofthe invention comprising upper substrate layer 162, lower substrate layer 166, vibration damping layer 164, hole 168, dero,lna~ion 170 in the upper substrate layer 162, and d~rol,llalion area 171, and d~r(~lllla~ion 169 in the lower substrate 166.
Fig lOD is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 172, lower substrate layer 176, hole 178, vibration danlpillg layer 174, d~rolmalions 180 and 179 ofthe upper and lower substrate layers 172 and 176, and de~llllalion area 181.
Fig. 1 OE is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 182, hole 188, vibration damping layer 184, lower substrate layer 186 and d~Ç~"",~lion 189 ofthe lower substrate layer 186, der~",.. alion 190 ofthe upper substrate 182, and derollllalion area 191.
Fig. lOF is a partial cross-section ofthe l~min~te article ofthe invention cGm~ g upper substrate layer 192, lower substrate layer 196, vibration damping CA 02206301 1997-0~-28 WO 96/21560 PCTrUS9S/16271 layer 194, hole 198, deformation 193 and protruding area 195 ofthe upper substrate layer 192, and d~;roll,lalion area 200.
Fig. lOG is a partial cross-section ofthe l~min~te article ofthe invention comprising upper substrate layer 203, vibration damping layer 202, lower substrate layer 204, recessed area 208 and protruding area 201 of the upper substrate layer 200, and deformation area 206, wherein derol-,.alion 208 can serve as the 7~tt?~c~im~nt area.
Fig. lOH is a partial cross-section ofthe l~min~te article ofthe invention comprising upper substrate layer 210, lower substrate layer 214, protruding areas 215 and 213, vibration damping layer 212, defollll~Lion area 218, and d~rolllla~ions 216 and 217 which can serve as the attachmçnt area.
Fig. lOI is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 220, vibration da,~-pillg layer 222, lower substrate layer 224, deformation area 228, protruding areas 223 and 225, and dero,llla~ions 226 and 227 which can serve as an ~tt~rhm~nt area.
Fig. 11 is a cross-section of the l~min~te article of the invention showing upper substrate layer 230, vibration damping layer 232, lower substrate layer 234, hole 238, defo.ln~lion 240 in the upper substrate layer 230 and d~rulllla~ion area 236.
Fig. 12 illustrates the method of the invention with a tool of the invention. A
punch tool 242 having a "V" shaped protrusion and surrounding gripping features is used to deform a l~min~te having upper substrate layer 244, vibration damping layer 246, hole 245, and lower substrate layer 248, which rests on l~min~te support surface 250.
Punch tools have working surface(s). The woll~ g surface is that part of the punch tool that comes into contact with the l~min~te during the usage of the punch tool.
Figures 13-32 show cross-sections of various tools that can be used to achieve some degree of deru,ma~ion in the substrate layer(s) and displ~cemP.nt of the vibration d~mping material. These tools are typically mounted in a sL~I-ping press 30 that ~ es the tool to the l~min~te surface(s) and applies the force to deform the CA 02206301 1997-0~-28 W O 96121560 PCTrUS95/1627 substrate layer(s) and displace the vibration damping material in the dt;ro.l"alion area and to plastically deform the substrate(s) to achieve the improved fa~tening systems force retention. These punches can be used with l~min~te~ that have holes or no holes.
S For l~min~tes with holes, the tool used will always be larger than theminimllm tli~met~r or radius point ofthe hole. Some tools or punches used to pierce holes, emboss, or coin areas of the l~min~te will have similar tool features, but are designed to acco.l.plish d;~ren~ functions in making the l~rnin~ted article. Forexample, Fig. 13A shows a tool punch used to pierce a hole. This punch could also be used to displace the vibration damping material and deform the substrate layer if used with a larger diameter than the hole. Other punches that could be used include but are not limited to those selected from the group consisting of round punches, flat punches, flat punches with a protrusion, bullet punches, and "~' styled punches as found in Figures 13-17, 19, and 22.
Fig. 13 is a side view of a known bullet punch 254 that can be used to make the article of the invention.
Fig. 13A is a side view of a known flat punch 255 that can be used to make the article of the invention.
Fig. 14 is a side view of a known round punch 256 that can be used to make the article of the invention.
Fig. 15 is a side view of a known "V~' punch 258 that can be used to make the article of the invention.
Fig. 16 is a side view of a known "V" punch 260 that can be used to make the article of the invention.
Fig. 17 is a side view of a known punch 262 having flat surface 265 and hemispherical protrusion 263 that can be used to make the article of the invention.
Fig. 19 is a side view of a known punch 270 having flat surface 271 and "V"
or conical protrusion 272 that can be used to make the article of the invention.

CA 02206301 1997-0~-28 WO 96/21560 PCTrUS95/1627 Fig. 22 is a side view of a known inverted "V" or inverted conical punch 290 having inverted conical feature 297 that can be used to make the article of the invention.
Fig. 18 is a side -view of an angled gripping feature round punch 266 of the S invention having hemispherical protrusion 268 and angled gripping feature 267 that can be used to make the article of the invention.
Fig. 20 iS a side view of an angled gripping feature "~' punch 274 of the invention with a blunt nose "~' protrusion 276 and angled gripping feature 275 that can be used to make the article of the invention.
Fig. 20A is a side view of an angled gripping feature "V" punch 279 of the invention with a symmetrical blunt nose "V" protrusion 281 and angled gripping feature 284 that can be used to make the article of the invention. Also shown is angle q 273 that is defined by the intersection of a first line tangent to a gripping feature surface and a second line passing through the center of symmetry of the protrusion but intersecting the first line at a point inside the protrusion and inside the punch tool, on a side of the punch tool having the end. Also shown is angle b 277 that is defined by the intersection of a first line tangent to a protrusion surface and a second line passing through the center of symmetry of the protrusion but intersecting the first line at a point outside the protrusion and outside the punch tool, on a side of the punch tool having the end.
Fig. 21 iS a side view of a strengthened gripping feature "~' punch 278 of the invention with a blunt nose "~' protrusion 280, angled gripping feature 282, andstren~th~ne~l7 tapered side 283 that can be used to make the article of the invention.
Fig. 23 iS a side view of a strength~nPd angled ~;pping feature "~' punch 300 of the invention with recessed frustoconical area 304 and recessed conical areas 302 and 306 and strengthened, tapered side 307, and gripping feature 303 that can be used to make the article of the invention.
Fig. 24 iS a side view of a ~;pping feature "V" punch 310 of the invention with frustoconical protrusion 312 and low angle gripping feature 314 that can beused to make the article of the invention.

CA 02206301 1997-0~-28 W O96/21560 PCTrUS95/16271 Fig. 25 is a side view of a ~ glh~ned gripping feature "V" punch 316 of the invention with blunt nose "~' protrusion 318, knuckle gripping P~t~n~ion 320 andstrengthened, tapered side 319 that can be used to make the article of the invention.
Fig. 26 is a side view of a flat punch 324 of the invention with slots and protrusions 326, 328, and 330 that can be used to make the article ofthe invention.
Fig. 28 is a side view of a stren~h~ned, vented, angle-gripping feature "V"
punch 340, of the invention with vent 348, gripping feature recess 350, "V"
protrusion 344, strengthPned sides 341, outer di~meter of punch 342, gripping feature peak 351 that can be used to make articles of the invention. Fig. 28 is the cross-section 28-28 of Fig. 27. Fig. 27 is the bottom view of the punch in Fig. 28.
Fig. 28A is a side view of a stren~hçned~ angled, gripping feature "V~' punch 360 ofthe invention with vents 362 and 364, glipping feature 370 and "~' protrusion 366 that can be used to make articles of the invention.
Fig. 29 is a side view of an angled, gripping feature "V" punch 372 of the invention having recessed conical areas 376, gripping feature 374, "~' protrusion 375, extension shaft 378, and extension end 380 that can be used to make the article of the invention along with the extension end providing a pre- or post operation to the article in conjunction with the derulllla~ion design ofthe punch.
Fig. 30 is a side view of an angled, gripping feature "V" punch 386 of the invention having gripping feature 388, recessed conical areas 390, extension shaft 392, and extension end 394 and "Vq' protrusion 391 that can be used to make the article of the invention along with the extrusion end providing a pre- or post operation to the article in conjunction with the d~rul Illalion design of the punch.
Fig.31 is a side view of a punch 400 of the invention having hemispherical protrusion 402 and gripping surface 404 with many small gripping features that can be used to make articles of the invention.
Fig. 32 is a side view of an angled gripping feature "~' punch 410 of the invention having angled gripping feature 412, many smaller gripping features 414, and frustoconical protrusion 416 that can be used to make articles of the invention.

CA 02206301 1997-0~-28 W O96/21560 PCTrUS95/16271 Fig. 33 is a side view of an embodiment of the article of the invention comprising upper substrate layer 420, lower substrate layer 424, vibration damping layer 422, hole 426, protrusion area 421, deformation 423, and d~rvlll.alion area 428.
Fig. 34 is a side view of an embodiment of an article of the invention having S upper substrate 430, lower substrate 434, vibration damping layer 432, dero-l-lalion 435, protrusion area 431, d~rolllla~ion area 500, and hole 433 in upper substrate 430.
Fig. 35 is a side view of an embodiment of an article of the invention having upper substrate layer 502, lower substrate layer 506, vibration damping layer 504, partially removed upper substrate plug 508, derc,llllalion 503, protrusion area 501, defolllla~ion area 510.
Fig. 36 is a partial cross-section of the l~min~te article of the invention comprising upper substrate layer 520, lower substrate layer 524, hole 526, vibration damping layer 522, damping layer bridging particles and/or fibers 528.
The punches useful according to the invention can be used to displace the vibration da~ g material and deform the substrate layer(s). Useful punches include known punches such as those in Figs. 13-17 and 19 and 22. Plerelled punches are those novel punches ofthe invention shown in Figs. 18,20-21,23-32. Useful punches typically have an aspect of the tool that applies force in more than onedirection to the l~min~te surface(s). For example, a first force is applied by the tool at an angle to the l~min~te surface and preferably at an angle towards the hole or att~çhmPnt area ofthe intPn~led derol...a~ion area. The gripping feature ofthe punch tool provides this first force. The force serves to push material to the hole (substrate and vibration damping material) and also can prevent the substrate layer from slipping away from the hole. A second force is applied in the hole area and is at an angle 25 cle~igned to apply the most force in the downward direction and outward from the hole. The protrusion of the punch tool provides this second force. The reslllt~nt of these two forces working together will concentrate the tool force in a manner todisplace the vibration damping material mass and deform the substrate(s). The tool design is based on the substrate materials used, hole size (if any), thickness of the 30 l~min~tç7 thickness of each layer in a l~min~tç~ vibration damping material used and CA 02206301 1997-0~-28 WO 96t21560 PCTIUS95/16271 layer t,vpes in the l~min~te The ~rere.lt;d types of punches designed for vibration damping material displ~cemPnt and substrate d~Ço....~lion to achieve optimum fastener force retention are those of the present invention. These punch configurations are not the full matrix of dç~ign~7 but de...ons~.~te the basic concepts S in using a tool specifically dç.~igned for l~min~ted article fastener device force retention optimization.
The punches of the invention may also have some unique requirements due to their design. For example, the punches may require "venting" or "slotting" to allow escape of fluids used in the stamping process that can be entrapped in cavities or 10 pockets the punch may form between the punch end and the l~min~te during the tool' s use. The entrapped fluid may not be highly co...,uressible and can impede the punch d~ro-...~lion of the l~rnin~te if not allowed to escape when under pressure. In addition, the punches may require added strength designs to prevent the tool from cracking, flexing, or having premature wear during the stamping process. The added 15 sl-t;nglh or support to the punch may be added by tapering the tool end to a wider shaft (tapering the shaft ~dj~cçnt to the tool end). This will add strength to the gripping features near an edge of the tool. The punches may also require a higher grade or di~ en~ grade of tool steel to ~nh~nce the tool life then may typically be used for other punch type processes on the l~min~te (for example, piercing, 20 embossing or coining).
The text handbook of metal forming (McGraw-Hill, Inc. Lange, ISBN 0-07-036285-8) gives a good overview of ~u..ping processes and equipment in general.
Thus the present invention relates to a l~min~te article with improved torque retention, a method of making the article and tools used to deform the substrate and 25 displace the d~--l,;ng material. The l~min~te articles of the invention provide f~tçnin~ systems having improved torque and/or force and/or pressure and/or stress retention. The present invention relates to a method of improving the torque and/or stress and/or force and/or pressure retention properties of a l~min~te structure by in~ the damping material in the l~,.".~le in the d~Çor~ ion area from an initial30 mass to a reduced mass that in turn reduces the torque lost in a retention device CA 02206301 1997-0=,-28 WO 96/21560 PCI'IUS95/16271 following attachm~nt or assembly of the l~min~te into a structure with the ~ttaçhm~nt device. The method further provides for a derollllalion or featuring ofthe substrate layer(s) ofthe l~min~te to ...;I.;...;,e the amount that the damping material can recover back mto the location it had been forced from and also to ~..;1-;...;7e the force required 5 to con-l)l ess the substrate layers together due to a residual spring effect between substrate layer(s) and can allow reduced dynamic friction in some fastener devices.
The present invention provides a method of improving the force retention in damping material l~min~te ~tt~chment devices, and thereby solving a problem withforce reduction in the fastener system due to the damping material stress relaxing 10 after the device is ~tt~çhed plus the need to overcome the spring effect between l~min~te layers and in some designs redur.inp~ the att~çhmPnt device and substrate dynamic friction.
More specifically, the present invention provides a l~min~te with the vibration damping material reduced from an initial mass in the derollllalion area to a lower 15 mass, plus deform the substrate layer(s) to reduce the spring effect, damping material recovery and lower ~tt~.hm~.nt device to substrate friction, to provide for a l~min~te with more fastener force retention after a given period of time and temperature as colllpal ed to a cover not using the invention.
The tools used to reduce the damping material mass are designed such that 20 the force of the tool displaces the vibration damping material in the derol Illa~ion area of the l~min~te article. The tool also plastically deforms the substrate layer(s) such that they reduce or inhibit the damping materials ability to recover to its original location in the l~min~te after the stamping operation. The substrate layer(s) are also plastically deformed such that they do not impart a resistive or spring force against 25 the ~tt~çhm~nt device when applied (i.e., when the damping material is displaced if the l~min~te layer springs back to its original location or recovers a pel centage of the amount it was deformed, this "spring" will need to be overcome by the att~çhmentdevice and this could reduce the overall torque retention).
The tool provides displ~c~o.m~nt of the vibration damping material mass to 30 minimi7e stress relaxation in vibration damping material in the dero,n,a~ion area, plus CA 02206301 1997-0~-28 useful deformation of the substrate layers to prevent vibration damping materialrecovery and substrate layer spring effect and reduction of ~tt~chm~nt device tosubstrate application friction. Typically the l~min~te is modified such that theimprovement in the force retention of the fastener device is at least about 5%
5 improved in co",p~ison to a l~min~te of the same construction and design, but not ili7ing the invention. Plerelled improvement is at least about a 20% increase, most prere"ed is at least about a 35% increase in the force retention ofthe ~tt~.hmf~nt device in an ~tt~hm~nt area at least partially contacting a defo""a~ion area as determined by the "T ~min~te Force Retention Test Method for T ~min~tes configured 10 with 'Through-Holes"' described below.
Useful tool designs are those that provide at least about a 5% improvement in fastener device force and/or torque and/or pressure and/or stress retention. Useful tool designs which accomplish the vibration d~"ping material displ~c.omPnt and plastic dero"nalion of the substrate layers include but are not limited to those tools 15 that have flat, round, bullet (such as pointed conical, etc.), "V" (conical) or flat with a protrusion style punch design. These tool designs should be such that the majority of the force is applied in the direction normal or pel~en~ic~ r to the l~min~te surface.
This can require a flat, flat with a protrusion, a round or a bullet punch to have a large radius as col-lpal ed to the ~ttachmPnt area or hole and a "V~' style punch with 20 small angles to the holizonlal of the l~min~te. Useful round, bullet, or flat style punches are those which have a radius (or equivalent over sizing for non-round holes) at least about 1.01 times greaterthan the hole or att~hm~.nt area ~ meter~ preferably at least about 1.5 times greater, and most p.ere,~bly at least about 2 times greater than the hole r~i~meter. The angle of the "~' style punch is typically from 1 degree to 25 89 degree as defined by the intersection of a first line tangent to the surface of the "V~' protrusion and a second line parallel to a surface of the tool shaft and passing through the center of the "~' type protrusion preferably from 20-89 degrees, andmost preferably from 30-89 degrees.
Plerellèd tool designs ofthe invêntion are those that includê gripping features 30 and at least one protrusion. The tools will deform the l~min~t~ in at least 2 main CA 02206301 1997-0~-28 W O96/21560 PCTrUS95/16271 directions. The direction of at least 2 of the forces generated by the punch tool's working surfaces are at angles to each other and the reslllt~nt forces or tool effect generates a displ~cemPnt of the vibration damping material mass and plastic d~ro""~lion of at least one substrate layer. The dtro""alion of the substrate layer(s) also preferably limits the residual spring effect of the substrates, reduces vibration damping material recovery and reduces dynamic friction losses during fastener devi'ce application. This tool design should achieve at least about a 5% increase in attachm~nt device force and/or torque and/or pressure and/or stress retention and may achieve greater than about a 35% improvement in retention as co",paled to a 10 l~min~te with no displ~s~m~nt ofthe vibration damping material and plastic deformation of the substrate layers. For a hole near the edge of the l~min~te att~c.llm~nt devices, the tool design is such that the protrusion contacts the inner edge ofthe hole and directs a portion ofthe l~min~te in an angled downward direction.The gripping feature(s) of the tool directs a portion of the l~min~te material in the 15 area surrounding the hole in an angled (opposite the protrusion) direction. The res-llt~nt forces of this tool will concentrate the forces in a fashion to displace the vibration damping material, provide for substrate dt;rc"",alion to reduce vibration d~lp-ng material recovery, reduce substrate spring effect and potentially reducedynamic friction.
The punch tool's protrusions include but are not limited to those selected from the group concicting of frustoconical, elliptical, spherical, hemispherical, bullet-shaped, cylindrical, and conical protrusions and variations between these. The gripping features include but are not limited to those selected from the group consisting of a textured surface(s), continuous ridges, discontinuous ridges, 25 continuous ridges having textured surfaces and discontinuous ridges having textured surfaces.
The tools used to displace the vibration darnping material may also partially close or further open the hole during the dt;ru""a~ion process. The hole ~ metershould be sPIected to take into account the tool design and the effect it has on the 30 hole rli~mP,tPr so that the reslt~nt article has its int~nded ~im~ncions.

CA 02206301 1997-0~-28 The plerelled tool design insl~ldes a symmetrical protrusion and gripping feature on the end of the tool. The protrusion has at least one angle as defined by the intersection of a first line tangent to a surface of the protrusion and a second line passing through the center of symmetry of the protrusion but intersecting the first line 5 at a point outside the protrusion and outside the punch tool, on a side of the punch tool having the end. The angle is between 0.5-89 degrees, preferably is from 20-89 degrees and most preferably from 30-89 degrees.
The gripping feature has at least one angle as defined by the intersection of a first line tangent to a surface of the gripping feature and a second line passing 10 through the center of symmetry of the protrusion but intersecting said first line at a point inside the protrusion and inside the punch tool, on a side of the punch tool having the end. The angle is between 0.5-89 degrees, prt;rt;lably is from 20-89 degrees and most preferably from 30-89 degrees. Fig. 20A is a cross-section showing an example of the angles, for a punch tool 279 having angle b 277 of the protrusion 281 and angle q 273 of the gripping feature 284.
Furthermore, the tool is usefully designe~ such that the defol ",alion of the l~min~te as caused by the gripping feature of the tool occurs as the protrusion part of the tool is also deforming the l~min~te The tool should be designed to concentrate and build the mech~nical forces on the da.ll~)ing material to cause the damping 20 materials displ~cement and plastic dt;~llll~lion ofthe substrate.
Fig. 36 illustrates the second l~min~te ofthe invention which comprises an upper substrate layer 520, lower substrate layer 524, vibration damping layer 522, hole 526, and particles 528.

25 T ~min~te Force Retention Test Method for T ~min~tes Configured with Through- holes The l~min~te force retention test measures the retained force of an att~cllment device after the device has been applied to the l~min~te in the desired test areas. The l~min~te has the test method ~tt~chment device applied and the assembly is allowed 30 to set for a prescribed period of time and at a temperature and humidity range plus CA 02206301 1997-0~-28 other em/irol-...k..l~l conditions ofthe article in its end use worst case application or in a modified environll.elll to the worst case condition.

A test to determine the benefit of the invention in a l~min~te article is conducted as follows:

1) Select the l~min~te to be tested.
2) Select a screw and associated sample base that has a tapped hole for the screw to be screwed into. The sample base and screw should be of the same base material as the end use application (ex: ~ mimlm, stainless steel, etc.). The screw should be the same or equivalent as used in the end use application.
The default screw and base materials are ~hlmimlm The default screw shaft should fit through the through hole in the l~min~te. The screw shaft diameter should be at least 20% of the hole area and the screw head sized to support the strength required to support the torque applied to it and to contact an area at least 5.0% the size of the hole, surrounding the hole.
- for l~min~tes without a hole in the ~tt~hm~nt area, a through hole could be added to the ~tt~r.hmknt area that is .05-10 times the nominal ~ thickness of the l~min~te in ~ meter. If the l~min~te has a deformation area, the hole should be centered in this area and be less than 95% of the de~llllalion area. If a hole is not desired, a clamp versus a screw chm~nt device can be used to conduct the test. The clamp should have a contact area to the substrate of at least .5cm2. The clamp device is of a "C" design with the force applied in a perpendicular extension to the l~min~te surface. The extension is a screw type extension so that a torque driver can be used to apply the clamp force.
3) Cut out from the l~min~te two samples by a method that does not affect the areas to be tested (by laser cutting, water jet cutting, shearing methods, etc.). The first sample is taken from the l~ e in an ~tt~rhm~nt area. Cut out a 30 sample that is at least 25% larger than the intlonded ~tt~-hment area. The comparison CA 02206301 1997-0~-28 WO 96/21560 PCI'IUS95/16271 samples should be taken from the l~min~te in an area that is not an ~tf~çhm~nt area, but has a l~min~te construction of the article with no substrate layer de~ a~ion.
- The comparison sample should be of the same size as the sample taken from the l~min~te to test the ~tt~çhm~nt area. The comparison sample may have a hole pierced into it by a ~l~,llping method or by laser cutting of the same size hole as the invention sample (if not present).
The area that the colllp~ison sample is taken from the invention should be from an area that has the sarne input substrate and damping materials configuration prior to the l~min~te being processed to an article.
4) Place the samples from the l~min~te (colllpalison sample and sarnple of the att~.~.hm~nt area) into a controlled environment (temperature, humidity, etc.) that duplicates the environment that the l~min~te would be applied to the base with the desired att~çhm~nt device. The default tel..pe.~ re and humidity is 65-75F and 30-70% relative humidity.
5) Apply the screw type or clamp type ~tt~çhm~nt device to the l~min~te s~--ples (comparison sample and sample of the ~tt~çhmPnt area) and the test base to the prescribed end use application torque down force that duplicates the environrnent that the l~min~te would be applied into the end use base. The default te--lpel~ re and humidity is 65-75F and 30-70% relative hurnidity. Use clean screws and clean surfaces for the test. (No oil or lubricants should be present on the surface) Torque down the screw to 100% +t- 5% of the application torque force with a torque driver 6) Set the torque applied samples into an environment that duplicates the worst case force loss envilolll..t;nl that the article will be subjected to during its use 25 after ~tt~hmPnt This is typically the highest temperature, highest humidity and worst case chemical en~ onlll~llL that the article will be exposed to after the fastener device is ~tta~hed Apply these conditions for a period of 24 hours. The default temperature is 100~C (212~F), and 30-70% relative humidity for 24 hours.

7) After the 24 hour test period, place the samples back into an 30 environment that duplicates the application environment used to apply the screw CA 02206301 1997-0~-28 f~.ctening device to the l~min~te samples and sample bases to bring the torque applied samples to the application tel"pel ~lure. The default temperature and humidity is 65-75~F and 30-70% relative humidity for 24 hours.

8) Measure the m~iml-m torque force required to remove the screws or 5 clamps from the l~min~te samples (comparison sample and sample of the fastenerarea) and co",pare the force measurements to co~"pare the samples force retention.

Method of Making the Article:
The method of making the article of the present invention typically involves 10 the displacement of the vibration damping material by means of a sla"~ping process.
The l~min~te is typically m~nllf~ct~lred by inco",o, ~lion of a vibration damping material as one or more interior layers of the l~min~te followed by the sLa."ping process. The vibration damping material may be layered in between the substrate(s) layers e.g., stainless steel and its alloys, carbon steel, ~ minllm and its alloys, 15 polyester, etc., ofthe vibration damping l~...;..AIe article.
Preferably, the l~min~ted material has the vibration damping material l~min~terl, sprayed, silk scl ~ened, or cast onto one or more layers of structural material. The vibration damping material layer can be continuous, or ~~iccontinllous The vibration d~mring material may subsLanl;ally form a layer having about the same 20 dimensions as the substrate layers between which it is sandwiched. Altemately, the layer may be of more limited dimensions and may be situated in an area of greatest vibrational stresses. Typically, an amount of the damping material is present such that the d~mpin~ characteristics of the article are improved over a non-l~ e or monolithic article. P~ t;fel ably~ a sufficient amount of the vibration damping material is 25 used such that the damping is improved by at least about 10% in at least one vibrational mode.
The l~min~te article of the invention utilizes the displacement of the d~mpin~
material, defc",naLion ofthe substrate and benefit ofthe vibration damping materials with a miniml~m impact on the article's structural geometry and stiffness while 30 providing improved f~tenPr force retention upon application to provide a optimized CA 02206301 1997-0~-28 W O96/21560 PCTnUS95/16271 damped l~min~te article. Thus, the articles of the present invention are good c~n~ tes for products that require vibration and shock resistance and control, reduced noise generation and tr~n.cmic.cion, along with improved force retention of the ~tt~chm~ont device that is used to hold the l~min~te of the invention in place.
Those skilled in the art can select the best means to introduce the damping material and the damping material displ~cçm~nt and substrate d~ro-.l.alion into a specific process based on the needs of the final l~min~te article of the invention and also limitations in processing capabilities of the l~min~te input materials.
The damping material can include a viscoelastic material or a combination of 10 viscoelastic material with the optional previously mentioned fibrous and/or particulate material. It is to be understood that the vibration d~..ping material can include a blend of viscoelastic materials as well as a variety of di~. ~ fibrous or particulate materials. Blends of fibrous and particulate material are also possible.
The desired thickness of the dan.pil-g material (in the l~min~te prior to plel)a ing the article ofthe invention) is typically about 0.002 mm to about 1.5 mm;
preferably, about 0.02 mm to about 1 mm; and most preferably, about 0.02 mm to about .25 mm. Typically, the thickness ofthe damping material is about 0.5 to about 50% of the thic~ness of the l~min~te, and more typically about 1 to about 25%. The article of the invention typically contains at least 1 damping layer, more typically 1-3 20 layers, preferably 1-2, most prere-ably 1 for reasons of simplicity of the article's m~mlf~ctllring process and cost. Stiffness may also be sacrificed when more than 1 damping layer is included. However, a wider temperature range of damping is possible when multiple layers of di~renl vibration dal--~Ji--g materials are included.
Sufficient damping material should be used to obtain the desired damping effect while 25 balancing the structural requi. c;lllen~S of the article. The vibration damping layer may be continuous or discontinuous. A continuous layer may comprise the same material or ~dj~c~.nt sections of di~ere--~ vibration damping materials or spaces or substrate material. A discontinuous layer may comprise sections of damping material separated by non-damping material and/or spaces. When 2 or more layers are present, the layers CA 02206301 1997-0~-2X
W O96121560 PCTrUS95/16271 may comprise the same or diLr~l elll damping material and each may be continuous or discontinuous.
The l~min~te article ofthe invention having improved f~t~nPr force and/or stress and/or torque and/or pressure retention can be made by any suitable technique 5 for creating articles as understood by those in the industry the article is being used.
For example, a cover for a disk drive application can be made by adding a single layer of a vibration damping material 0.05 mm thick near the center of the cover by l~min~ting a layer of stainless steel with a layer of suitable viscoelastic damping material and an additional layer of stainless steel. This l~ te is then stamped with 10 various tools and dies that provide the needed part definition (embossing, bl~nking, forming, coining, etc.) as ~ c~ ed in the st~mrin~ reference. The final l~min~ted cover during this ~L~Ilping process has holes pierced in it to provide a path for the f~tçner devices (screws) to hold the cover securely to the base (and to other components, such as an actuator and spindle motor, if desired). The f~tçn~r areas 15 are further modified either before or after piercing with a tool punch of the invention to displace the vibration danll)ing material, impart a derollllalion into the st~in'ess steel to reduce the vibration damping material's recovery and ...;.I;~ e residual spring effect belween the ~lail1leSS steel layers and to feature the ~tt~çhm~nt area such that dynamic friction is recl~lcecl~ to provide a l~ ed disk drive cover with 20 improved force and/or torque and/or pressure retention in the f~tçn-ng system as co,lll,a,ed to l~ ed covers not modified for improved fastener force retention.
Examples of l~min~ted articles which may be produced with improved force and/or torque and/or pressure retention characteristics include but are not limited to those sçlected from the group consisting of covers, panels, housings, baffles, pans, 25 colllai~el ~, and ducts and other applications where conventional methods to improve the force retention of the fastener system in a l~min~ted article are not practical, cost effective, sufficiently effective to meet design goals or are limited by initial force that can be used to apply the f~t~n~r system. F.Y~mple of specific articles include but are not limited to those selected from the group cons;s~ g of vehicle oil pan covers, disk 30 drive covers, vehicle valve covers, appliance panels, vehicle panels, acoustical panels, CA 02206301 1997-0~-28 WO 96/21S60 PCTtUS95/16271 l~min~ted sheeting panels, building panels, aerospace panels, heating panels, ventilation panels, air conditioning panels, motor housings, appliance housing, equipment housings, fluid baffles, acoustical baffles, vehicle oil pans, shipping containers, holding co"laine,s, storage containers, transportation containers, heating S ducts, ventilation ducts, air conditioning ducts and cooling ducts.

Exan~ples The invention has been described with reference to various specific and prere.,ed embo-lim~nt~ and will be further described by reference to the following detailed Examples. It is understood, however, that there are many extensions, variations, and modifications on the basic theme of the present invention beyond that shown in the exarnples and detailed description, which are within the spirit and scope ofthe present invention. All parts, pe~ce~ g~ ratios, etc., in the Spe~ific~tion and the Examples are by weight unless indic~ted otherwise.
Examples 1-2 and ComParative Example 1 In s)rder to evaluate the pelrOllllanCe of a damped l~min~te with improved fastener force retention, a sample article was prepared by adding a layer of a 0.05 l mm damping material in a construction that had exterior layers of stainless steel at 0.030 inches and 0.037 inches (0.76 mm and 0.94 mm, respectively). The l~min~te construction was then processed in a tool to add pierced holes, embossing and the displacement of the darnping material and derol ",alion of the stainless steel layers in the defollllalion areas. (Examples 1 and 2). Two style of punches were used for these Exa",plcs.
The constructions of Ex~ples 1 and 2 were cG",pa~ ed to a similar article made in the same tooling and procêss except without the displ~cem~nt of the damping material and defo""alion of the stainless steel layers in the deformation areas, thereby not irnproving the force retention of the Co"")a, ~ re Example.

CA 02206301 1997-0~-28 wo 96/21S60 Pcr/uss5/l627 Description of SamDle For the purpose of demonstrating the invention, an acrylic damping material was used in the damped l~min~te article. The damping material used was an acrylic polymer that had a loss factor greater than 0.5 for a broad frequency range (+/- 1000 5 Hz) at the desired test temperature (20~C/ 72~F). The acrylic damping polymer se~ected was 3M Scotch(l~mr~M ISD-l 12, SJ2015 type 1202 available from Minnesota Mining and ~m-f~ctl.ring Company, St. Paul, Minnesota). The damping material was placed as an inner layer of a ~lainless steel damped l~min~te construction. This l~min~te construction was then processed through a stamping 10 operation to produce a completed damped l~min~te article as described below.

Examples 1 and 2 A 0.051 mm thick sheet of acrylic polymer damping material (3M Scotch-1~mrTM ISD-l 12) was placed (l~min~ted) between layers of stainless steel [one 0.030 inch (0.76 mm) and the other 0.037 inch (0.94 mm thick)~. The damping material was l~min~ted onto the initial stainless steel layer and the second ~l~nlcss steel layer was added onto the damping material to create a l~min~te construction. The damping material selected had room temperature pressure sensitive bonding characteristics, so no heat and only modest pressure with a rubber roller was required to create the l~min~te material. The damped l~min~te material was then processed through several sl~ g operations to form a co",pleted article, a disk drive damped l~min~te cover.
The l~ e input material was initially put into a meGll~nical press that can apply significant pressure to the l~ e material as it is positioned between a die and punch set-up. Press tonnage was typically 50 tons (4.54x104 kg) or more. The die and punch set-up are designed as to impart a particular feature into the l~min~te material. The basic process steps for the damped l~min~te cover of the Examples 1 and 2 in~ ded operations to emboss the cover (displace the l~min~te material to 2 or more hol~unlal levels), pierce the cover to add holes for screws, and the mal blanking or cutting out of the part from the excess l~min~te material.

CA 02206301 1997-0~-2X
W O96/21560 PCTrUS95/16271 An additional process was added for these covers before the blanking process.
This added process was to add a stamping step where the damping material was displaced and the stainless steel substrate plastically deformed in the screw hole att~hmPnt area. This process was added to improve the torque retention of the 5 screw f~tening system.
Example 1 used a tool of a configuration as found in Fig. 19 . Example 2 used a tool of a configuration as found in Fig. 24. The tool types shown were used tomodify the pierced hole to rlicpl~ce the damping material and plastically deforrn the stainless steel layer. For the tools used in the examples, the tools were centered on 10 the pierced holes and applied in such a manner (press stroke and tonnage) that the l~min~te was deformed and the damping material displaced. The degree of deformation ofthe substrate and rii~pl~cempnt ofthe damping material was indicated by the degree of hole area reduction (the tools used can reduce the hole di~metP,r or size depending on the deformation desired) and as indicated by the depth of the 15 gripping feature or flat into the stainless steel layer and penetration of the protrusion against the inner portion of the through holes. . For the Examples 1 and 2, the hole reduction was targeted at b~;Lween 82-90% of the initial hole size and a depth of between 0.001 and 0.004 inch (0.025 and 0.100 mm). For the gripping feature or flat into the stainless steel surface. The acrylic polymer sheet completely covered the 20 inner surface of each cover article.
The through holes were 0.132-0.141 inches (3.35-3.58 mm) in diameter. The deformation area extended 0.030-0.100 inches (0.76-2.5 mm) around the through holes. The ~/tt~Cllmçnt screws were ~hlminllm with a shaft diameter of 0.114-0.118 inches (2.9-3 mm) and a head ~ mp~ter of 0.216-0.224 inches (5.5-5.7 mm). The base 25 was ~lumimlm Comparative Example 1:
Co,l,pa~ a~ e Example 1 was pl c;p~ ~d according to the procedure of Example 1 and 2 except that the process to displace the damping material and plastically30 deform the stainless steel layers was not used in the screw ~tt~chmPnt area.

CA 02206301 1997-0~-28 W O 96/21560 PCTrUS95/16271 Test Method and Set-up:
The disk covers of Examples 1 and 2 and the Compa~ e Example 1 were all tested in the same test set-up and method.
s The covers were tested as follows:
1) The disk drive cover is one of many parts of a disk drive. The cover fits onto a base or housing that the other components of the disk drive are set into. The cover has eight pierced holes, of which six are found on the outer edges of the cover.
10 One hole is present at each ofthe four corners ofthe roughly 4 inches x 6 inches (10 cm x 15 cm) metric cover. The other two holes are found near the edge of the mid-point of the long side of the cover. The covers six holes are in ~lignm~nt with tapped holes in the base of the disk drive. Screws are used to hold the cover securely to the base. See Figures 1 and 2 for sçh~m~tic details of the base housing and l~min~te15 cover. The screws are fit through the l~min~te covers pierced holes and into the base's tapped holes. The screws are torqued to 9 inllbs (10 cm/kg) to apply a holding pressure between the screw head and cover which in turn holds the cover securely to the base.
2) The fastener device used was an ~hlmimlm screw. The screws were placed 20 in each of the outer holes of the cover and lightly tightençcl 3) The screws were then tight~ned to 9 in/lbs (10 cm/kg) using a SEEKONK
Precision Tools inch/pounds torque driver.
4) The l~min~te cover and base assembly following torquing was allowed to sit at room tel~i)c'~ re (70~F, 21~C) for 24 + 1 hours to allow the relaxation of the 25 f~t~ning device and l~min~te to occur.
5) A~er the relaxation time is complete, the force to undo the screw was measured by using the torque driver in the opposite direction. The torque driver has a dial indicator that shows the amount of torque being applied to the screw in theopposite direction of initial torquing. The screw torque driver will have a m~ldmllm 30 value of torque required to remove the screw from the assembly. The "break" or CA 02206301 1997-0~-28 WO 96/21560 PCI~/US95/16271 m~xim~lm force required to begin turning the screw to remove it is recorded and the data is used to assess the benefit of the invention as Co~ odl ed to a cover without the invention.
The data is colllpaled for each l~min~te cover design based on the average of 5 the six holes tested in each cover design.
The average torque out data for each cover design (6 holes each) is found in Table 1. The data below is the average for 4 covers tested in each construction.

Example No. Torque out Normalized to initial torque value cm-kg (in-lbs)(9.0 in-lbs, 10 cm-kg) % retention And also in comparison to Colll~ e Example 1 Ex. 1 8.5 (7.4) 82.2%
+ 34.5%
Ex. 2 8.8 (7.6) 84.4%
+ 38.3%
Comp.Ex. 1 6.35 (5.5) 61.1%

From the data in Table 1, it can be seen that the displ~cçm~nt of the damping material and the plastic d~;rul Illalion of the stainless steel layer significantly improved the average torque out retention value as colll,~aled to a cover with no modification.

The folegoing detailed description and Examples have been given for clarity of underst~ntlin~ only. No llnnecess~ry limitations are to be understood therefrom.
The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be in~ ded within the invention defined by the claims.

Claims (17)

WHAT IS CLAIMED IS:

1 A laminate article comprising:
a first substrate layer and a second substrate layer;
at least one layer of vibration damping material comprising a viscoelastic material positioned between said first and second substrate layers;
optionally one or more additional substrate layers positioned between said first and second substrate layers;
optionally 1 or more bonding material layers bonded between a substrate layer and a vibration damping layer, wherein the storage modulus of each bonding material layer is higher than the storage modulus of the viscoelastic material contained in a vibration damping layer to which it is bonded;
wherein the storage modulus of each substrate layer is greater than that of the viscoelastic material in any vibration damping material layer with which it is in contact;
wherein at least one deformation area is present in said article, wherein a deformation area is an area of the article wherein at least one substrate layer is plastically deformed such that at least two substrate layers are touching or positioned closer to each other than in an area of the article in which none of the substrates are plastically deformed;
wherein in at least 1 vibration damping material layer, within at least a 5%
area of the deformation area, the vibration damping material is non-existent or, if present, has a mass that is 90% or less than the average mass of the vibration damping material layer of an equal area in an area of the article which is not in a deformation area;
wherein at least one substrate has a variable thickness in a deformation area; and wherein at least one of the first and second substrates contains protrusion(s) and/or depression(s) in a deformation area.

2. The laminate article of claim 1 wherein at least one hole is present in a substrate selected from the group consisting of the first substrate layer and the second substrate layer, wherein at least one hole is surrounded by a deformation area.

3. The article of claim 1 wherein the substrate layers are selected from the group consisting of metals and plastics.

4. The laminate article of claim 1 having at least one layer of vibration damping material contained therein, said vibration damping material comprising a viscoelastic material, said vibration damping material having a loss factor of at least about 0.01 and a storage modulus of at least about 6.9 x 103 Pascals.

5. The article of claim 1 selected from the group consisting of covers, panels, casings, housings, baffles, pans, containers, and ducts.

6. The article of claim 1 wherein at least one vibration damping material layer further comprises an additive selected from the group consisting of fibers, particulates, and mixtures thereof;
wherein the total amount of additive is about 1 to about 90 weight percent based upon the total weight of the vibration damping material;
wherein the particulate size ranges from about 0.02 to about 125% of the average thickness of the vibration damping material layer, in which the particulate is present, and in an area which is not a deformation area; and wherein the fiber diameter ranges from about 0.02 to about 125% of the average thickness of the vibration damping layer, in which the fiber is present, in an area which is not a deformation area.

7. The article of claim 1 wherein the vibration damping material layer within atleast a 5% area of the deformation area, is nonexistent or, if present, has a mass that is 50% or less than the average mass of the vibration damping material layer in an equal area of the article which is not a deformation area.

8. The laminate article of claim 1 wherein at least one through hole is at least partially present in the article, wherein at least one hole is surrounded by a deformation area, wherein the area of each deformation area surrounding at least one hole is about 0.05 to about 10 times the area of each hole.

9. A fastening assembly comprising the article of claim 1 and at least one attachment device positioned thereon, wherein at least one attachment device at least partially contacts at least one deformation area of the article.

10. A fastening assembly comprising the article of claim 1 having at least one attachment device positioned thereon, wherein the attachment device is selected from the group consisting of screws, bolts, clamps, nails and rivets.

11. A method of preparing a laminate article comprising the steps of:
(a) preparing a laminate comprising at least one layer of vibration damping material, the vibration damping material comprising a viscoelastic material, wherein the vibration damping material is positioned between a first substrate layer and a second substrate layer, and optionally one or more additional substrate layers positioned between said first and second substrate layers wherein each substrate layer has a higher storage modulus than the viscoelastic material in any vibration damping material layer with which it is in contact, optionally 1 or more bonding material layers bonded between a substrate layer and a vibration damping layer, wherein the storage modulus of each bonding material layer is higher than the storage modulus of theviscoelastic material contained in a vibration damping layer to which it is bonded;
(b) forming at least one deformation area in the laminate article by impinging a punch tool against at least one area of at least one substrate layerselected from the group consisting of said first and second substrate layers to plastically deform one or more substrate layers, such that at least two substrate layers are touching or positioned closer to each other than in an area of the article in which none of the substrate layers are plastically deformed, wherein within at least 1 vibration damping layer, within at least a 5 % area of the deformation area, the vibration damping material is non-existent or, if present, has a mass that is 90% or less than the average mass of the same fibration damping material layer in an equal area of the article which is not a deformation area, wherein at least one substrate has a variable thickness in a deformation area ; and wherein at least one of the first and second substrates contains protrusion(s) and/or depression(s) in a deformation area.

12. A punch tool comprising a shaft having an end wherein said end comprises (i) at least one protrusion; and (ii) at least one gripping feature.

13. The punch tool of claim 12 wherein only 1 protrusion is present, wherein said protrusion is centrally located in said punch tool end, and wherein the grippingfeature(s) are angular feature(s) having nonparallel sides.

14. The punch tool of claim 12 wherein one symmetrical protrusion is present and wherein at least one angle as defined by the intersection of a first line tangent to a surface of the protrusion and a second line passing through the center of symmetry of the protrusion but intersecting said first line at a point outside said protrusion and outside said punch tool, on a side of the punch tool having said end, is present, said angle having a measurement of from about 0.5 to about 89 degrees.

15. The punch tool of claim 12 wherein one symmetrical protrusion is present and wherein at least one angle as defined by the intersection of a first line tangent to a surface of a gripping feature and a second line passing through the center of symmetry of the protrusion but intersecting said first line at a point inside said protrusion and inside said punch tool, on a side of the punch tool having said end, is present, said angle having a measurement of from about 0.5 to about 89 degrees.

16. The article of claim 1 wherein at least 1 vibration damping layer is thermally conductive, electrically conductive, or thermally and electrically conductive.

17. A laminate article comprising:
a first substrate layer and a second substrate layer;
at least one layer of vibration damping material comprising a viscoelastic material positioned between said first and second substrate layers, wherein at least 1 vibration damping layer is thermally conductive, electrically conductive, or thermally and electrically conductive;
optionally one or more additional substrate layers positioned between said first and second substrate layers;
optionally 1 or more bonding material layers bonded between a substrate layer and a vibration damping layer, wherein the storage modulus of each bonding material layer is higher than the storage modulus of the viscoelastic material contained in a vibration damping layer to which it is bonded;
wherein the storage modulus of each substrate layer is greater than that of the viscoelastic material in any vibration damping material layer with which it is in contact;
wherein at least one vibration damping material layer further comprises an additive selected from the group consisting of fibers, particulates, and mixtures thereof;
wherein the total amount of additive is about 1 to about 95 weight percent based upon the total weight of the vibration damping material;
wherein the particulate size ranges from about 10 to about 125% of the average thickness of the vibration damping material layer in which the particulate is present;
wherein the fiber diameter ranges from about 10 to about 125% of the average thickness of the vibration damping layer in which the fiber is present;
wherein the load bearing capacity of the additive is at least about 6.9 .103 Pa (100 psi)