CA1134096A - Sealing of integrated circuit modules - Google Patents
Sealing of integrated circuit modulesInfo
- Publication number
- CA1134096A CA1134096A CA341,841A CA341841A CA1134096A CA 1134096 A CA1134096 A CA 1134096A CA 341841 A CA341841 A CA 341841A CA 1134096 A CA1134096 A CA 1134096A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- hardener
- flexibilizer
- integrated circuit
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/02—Containers; Seals
- H01L23/04—Containers; Seals characterised by the shape of the container or parts, e.g. caps, walls
- H01L23/053—Containers; Seals characterised by the shape of the container or parts, e.g. caps, walls the container being a hollow construction and having an insulating or insulated base as a mounting for the semiconductor body
- H01L23/055—Containers; Seals characterised by the shape of the container or parts, e.g. caps, walls the container being a hollow construction and having an insulating or insulated base as a mounting for the semiconductor body the leads having a passage through the base
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/02—Containers; Seals
- H01L23/10—Containers; Seals characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/10—Bump connectors; Manufacturing methods related thereto
- H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
- H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
- H01L2224/161—Disposition
- H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/013—Alloys
- H01L2924/0132—Binary Alloys
- H01L2924/01322—Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/10—Details of semiconductor or other solid state devices to be connected
- H01L2924/102—Material of the semiconductor or solid state bodies
- H01L2924/1025—Semiconducting materials
- H01L2924/10251—Elemental semiconductors, i.e. Group IV
- H01L2924/10253—Silicon [Si]
Abstract
Abstract The hermetic seal of the backside of a substrate of an integrated circuit module is provided by a composition containing about 51.4 to about 60.6% by weight of an epoxy polymer; about 39 to about 48% by weight of a hardener and flexibilizing portion; and up to about 0.6% by weight of a coloring agent.
Description
~L~L3~
SEALING OF INTEGRATED CIRCUIT MODULES
Description Technical Field The present invention is concerned with an integrated circuit module wherein the backside of the substrate which contains the integrated circuit chip(s) is her-metically sealed to a cap by an improved epoxy compo-I sition, and to the improved composition. In addition, the present invention is concerned with the process or hermetically sealing the backside of the substrateof an integrated circuit module by employing certain epoxy compositions. The present invention is particu-larly concerned with those integrated circuit modules which contain a substrate having electrically-conductive pins protruding therefrom and having attached to the backside of the substrate at least one integrated cir-cuit chip, and including a cap or containeE into which the substrate is placed with the backside thereof being covered by the bottom of the cap or container.
.:
Background Art During the preparation of integrated circuit modu'es, certain epoxy compositions have been employed to her-metically seal the backside of the substrate on which is attached at least one integrated circuit chip.
Such compositions are emplOyed to protect and seal the electrically active portions of the module.
In order for a aomposition to be commercially aoceptable `'~
~ ,~.
~ , . ._, ~3~6 for sealing integrated circuit modules, it must possess a number of critical properties. In particular, the composition must be a nonconductor of electricity and must be capable of withstanding degradation due to expo-sure to various chemicals such as organic sol~ents and due to the e~fects of being exposed to the flow of electricity over extended periods of time. In addition, the composition must be resistant to reversion to non-fully cured products under ad~erse conditions of ele-vated temperature and high humidity over extendedperiods of time such as for at least about 10~years to be usable for integrated circuit packages to be employed in modern day computers. The compositions must also possess significant strength characteristics so as to resist deterioration when subjected to mechanical stresses. The compositions should also have good flexi-bility and be able to withstand thermal cycling (i.e., expansion and contraction due to temperature changes) without cracking. The compositions also must be resistant to permeation and diffusion of gases and sol-vents. Moreo~er, the composition must adhere tenaciously to the particular substrate employed.
' Since about 1974, the assignee of t:he present applica-tion, International ~usiness Machines Corporation, has employed a composition with ingredients containing about 47.6% by weight of a bisphenol A - epichlorohydrin epoxy polymer; about 5~% by weight of a hardener and flexibilizer mixture and about 0.4% by weight of a coloring agent. The hardener and flexibilizer mixture contains about 25 to 39~0 of hexahydrophthallc anhydride;
about 50 to about 75% by weight of a polypropylene glycol and/or polyoxypropylene glycol flexibilizer;
about 0.85 to about 1% by weight of a tertiary amine ~e.g., trimethyl amine); and a minor amount of hexa-hydrophthalic acid resulting from hydrolysis of the corresponding anhydride.
.. ... . _ . _ . _ _ . . .. ... _ _ _, _ .. , ~L3~L09~
~he coloring ag~nt employed is generally a mixture of chlorl~ated copper phthalocyanine on a titanium dioxide pigment.
This composition fox the mast part has been qu~te S satisfactory for its intended purpose as a potting or encapsulating composition used to seal the backside of an integrated circuit module or package. For in-stance, the solvent resistance, electrical resistance, I mechanical resistance, and reversion properties are commercially acceptable.
However, the flexibility of this composition is not entirely satisfactory. In addition, this commercially employed composition suffers from the disadvantage of insufficient resistance to cracking due to thermal cycling. When cracking occurs, substances in the sur-rounding environment (e.g., moisture) can come into contact with the backside of the module and cause problems such as corrosion of electrically active parts of the module resulting in reduced reliability. Accord-ingly, when cracking of the coating occurs,~the moduleas such is not used. The craclcing due to thermal stress became quite pronounced when the length of the sides of the modules was increased above 28 millimeters such as to about 36 millimeters. For instance, modules of 28 millimeters or less on a side have failures of about 1 to 4% due to thermal cracking when employing the above commercial composition. Failures in this range are commercially tolerable. ~owever, upon increasing the substrate size to at leas~ about 36 millimeters on a side, the failures increased to between 10 and 30% with the above compositions. These rates of failure are not commercially acceptable.
Accordingly, it is an object of the present invention ~' to provide a sealing composition which is less suscep-tible to thermal stress cracking than the now c~mmercially EN~79007 employed compositions discussed hereinabove~ A fur-ther object of the present invention is to provide a sealing composition which is more flexible than the above mentioned commercially employed epo~y composi-s tion. A major difficulty in overcoming these .defi-ciencies and problems is not to cause a deterioration in the other essential properties for a sealant to be employed in the preparation of integrated circuits.
Surprisingly, the present invention provides for at least as good mechanical, electrical, and chemical resistances as achieved in the above-discussed commer-cially acceptable composition and at least as good if not better reversion properties while at the same time increasing the ability to withstand thermal cycling without cracking and increasing the flexibility.
The increased flexibility and increased ability to withstand thermal cycling are quite surprising since ; the present invention employs less of the hardener and ; flexibilizer mixture than is used in the above-discussed commeLcially employed composition.
; Another problem experienced with the above-discussed commercially employed composition is referred to as - "run-in". "Run-in" refers to the flow of the composi-tion downward into the cap or can used to cover the backside of the substrate. This occurs at space gaps at the corners between the substrate which generally has a slightly rounded edge and the cap or can which are generally square. If the composition flows com-pletely to the underside of the substrate, then problems in reliahility could be caused by destruction of solder joints u~on thermal expansion. This problem has been compensated for by closely fitting the cap or can to the substrate such as by crimping the cap or can.
The present invention significantly reduces, if.not elimlnates, this problem of run-in. The compositions of the present invention resist flow downward to an undesired extent to the bot-tom of the cap or can, while at the same time flowing vertically when dis~
pensed to cover the entire substrate and contact -the upstanding walls of the cap or can adjacent the sub-stra-te to form the seal. Accordingly, the use of the present invention makes it possible to tolerate larger gaps at the corners between the substrate and cap; and thereby, making it possible to use less crimping than previously re~uired. Reduced crimping in turn reduces mechanical stress on the back seal compositions which are used to coat the integrated circuit chip.
Disclosure of the Invention .. . .... _ .
The present invention is concerned with. an integrated circuit module containing a substrate having electrically-conductive pins protruding therefrom, and having attached to the backside thereof at least one integrated circuit chip. The backside of the substrate is contained within a cap or can and is hermetically sealed thereto by a composition applied over the exposed surface of the substrate and over a portion of the height of the pins. The composition contains about 51.4 to about 60.6~ by weight of an epoxy which consists essentially of a bisphenol A -epichlorohydrin epoxy polymer; about 39 to about 48~
by weight of a hardener and flexibilizer portion; and up to about 0.6~ by weight of a coloring agent. The bisphenol A - epichlorohydrin polymer has an epoxy e~uivalent weight of about 1 ao to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25C.
The hardener and flexibilizer portion contains about 15 to about 49% by weight of an anhydride hardeneri about 40 to about 85% by weight of a polyalkylene glycol and/or a pol~oxyalkylene gl~col ~le~ibili~er;
up to about 1~ of a tertiary amine catalyst for the epoxy; and minor amount of an acid resulting from the hydrolysis of the corresponding anhydride hardener.
The maximum amount of the acid is such that the acid number of the hardener and flexibili~er portion does not exceed about 4.0 mg KOH/gram.
The polyalkylene glycols are polyoxyalkylene glycols having molecular weights so that the viscosity of the hardener and flexibilizer portion is about 900 to about 2500 centipoise at 25C.
The present invention is also concerned with the above-discussed composition.
Furthermore the present invention is concerned with a process for hermetically sealing the backside oE
the substrate of an integrated circuit module. The process includes providing a substrate having electrically-conductive pins protruding therefrom and having attached to the backside thereof at least one integrated circuit chip. The substrate with the chip attached thereto is placed into a cap or can wherein the backside of the substrate is covered by the cap or can. The composition discussed hereinabove is provided over the e~posed surface o~ the substrate and a portion of the height of the pins and is then cured in order to hermetically seal the backside of the substrate within the gap or can.
The Figure is a schematic cross section of a module in accordance with the present invention.
~1 The present invention is also generally discussed in IBM*Technical Disclosure Bulletin Volume 20 No. 10 `` March 1978 prepared on behalf of the inventors of this application.
*Registered Trade Mark , ~ EN979007 , _ , _ ................ ..
~L3~
Bes-t Mocle for C2rryin~ out Invention The epoxy polymers employed according to the present invention are diglycidyl ethers of bisphenol A - ~
epichlorohydrin. The epoxy polymer component can also contain minor amounts (e.g., up to about 5~ by weight) of other types of epoxides such as phenyl-glycidyl ether.
The epoxy polymers employed according to the present invention have an epoxy equivalent weight of about 180 to about 210 and should have a viscosity of about 6,500 to about 22,500 centipoise at 25C. Some exampIes o~
epoxy polymers suitable for the present invention ~hich are commercially available from Shell Oil in-15 clude Epon*820, Epon g26, Epon 830, and Epon 828.
; Epon 82~ is a diglycidyl ether of bisphenol-A - epi-chlorohydrin having an epoxy equivalent weight of 185 ~ to 192 and viscosity of 10,000 to 15,000 CPS at 25C.
- ~pon 820 is a mixture of Epon 828 with about 2 to about 5% by weight of phenyl glycidyl ether, and has ; an epoxy equivalent weight of 180 to 195 an~ a vis- ,~
cosity of 6,500 to 10,000 CPS at 25C. Epon 826 is a diglycidyl ethex of bisphenol A - epichlorohydrin ~ . .
~ having an epoxy equivalent weight of 180-188 and a -~ 25 viscosity of 6,500 to 9,500 CPS at 25C. Epon 830 is a diglycidyl ether of bisphenol A - epichlorohydrin having an epoxy equivalent weight of 190 to 210 and a viscosity of 15,000 to 22,500 CPS at 25C. , The hardener and flexibilizer portion of the comp,osi-tion incLudes an anhydride hardener or mi,~ture of anhydrides for the epoxy, and a polyalkylene glycol and/or polyoxyalkylene glycol flexibilizer. The hardener ,and fle~ibilizer portion can also include a tertiary amine catalyst for the epoxy and minor amounts of acid(s) which can result from the hydrolysis Df the *Trade Mark " ... . . . ., . .. . _ ... ... _____ . .. . . .. _. _ .-- _ . . ._ . _ ._.. _, ~
"
corresponding anhydride(s), By includiny the above component in the hardener and flexibilizer pOrtiQn, it is not intended to mean that these must be premixed together separately prior to admixing with the epoxy.
These components have been recited in this manner so as to facilitate the calculations and disclosure with respect to the relative amounts of ingredients which must be employed.
The hardener is an anhydride such as nadic methyl anhy-dride and preferably a phthalic type anhydride such as hexahydrophthalic anhydride and tetrahydrophthalic anhydride. ~ixtures of anhydrides can be employed if desired. The anhydride is present in amount of about 15 to about 49% by weight and preferably 25 to about ;~ 15 39% by weight based upon the weight of the total weight of the anhydride, flexibilizer, tertiary amine and acid in the hardener and flexibilizer portion of the composition.
The flexibilizer is a polyalkylene glycol and/or poly-oxyalkylene glycol which can be represented by the formula:
HO-R-O-[-R O-]n-R-OH
wherein R is a divalent saturated aliphatic hydrocax-bon moiety selected from the group of ethylene, propylene,~butylene and mix~ures thereof, These groups can be straight or branched chained, ~'` , Mixtures of these glycols can be employed if desired.
The n is 0 or an integer such that the molecular weigh-t thereof in conjunction with the amount used is such that the viscosity of the hardener and flexibilizer portion is about 900 to about 2,500 centipoise at 25C, Examples of some suitable glycols include polyethylene glycol, polyoxyethylene glycol, polypropylene glycol, polyoxypropylene glycol, polyoxyethyleneoxypropylene , 35 glycol, and polybutylene glycol. The preferred ~lycols are polypropylene glycol and polyoxypropylene glycol.
The glycol or glycols are present in amounts of about 40 to about 85% and preferably about 50 to about 75~
by weight based upon the total weight of the h~rdener and flexibilizer portion of the composition.
A ter~iary amine curing agent musk also be employed.
The preferred tertiary amines include the saturated aliphatic monoamines such as trimethyl amine and triethyl amine. The tertiary amine can be employed in amounts of 0.1 to about 1% and preferably about 0.85 to about 1~ by weight based upon the total weight of the hardener and flexibilizer portion of the composition.
In addition, minor quantities of acid(s), e.g., up to about 1% or more based on the weight of the hardener and flexibilizer portion, might be presbnt due to hy-drolysis of the corresponding anhydride(s). The maxi-mum amount of acid is such that the acid number of the hardener and flexibilizer por~ion not exceed about 4.0 mg KOH/gram.
: , .
The compositions can also include a coloring agent.
` Such is employed as a visual means to determine whether there is contamination of the composition on the parts of the pins which are not to be coated. The presence ; of the coloring agent also enhances inspection to ; 25 determine whether the composition has adequately covered the substrate surface and~joined to the cap or can.
.
The preferred coloring agents lnclude the phthalocya-nine dyes and most preferably are mixtures of chlori-nated copper phthalocyanine (a green dye) andtitanium dioxide pigment. Such is commercially avail-able in the form of a mixture with a bisphenol A -epichlorohydrin epoxy polymer of the type employed in ~3g~6 the present invention under the trade designation Hysol. The commercially available Hysol compositions contain about 20~ by weight of the chlorinated or polychloro copper phthalocyanine and titanium dioxide mlxture and about a o% by weight of the bisphenol A -epichlorohydrin epoxy resin (Shell Epon 828). Mixtures of coloring agents can be employed if desired.
- If it is desired to provide a clear, transparent com-position, then no coloring agent would be employed.
The compositions employed according to the present invention, in order to obtain the improved results discussed hereinabove without a concomitant deteriora-tion in the other essential characteristics, must include the following relative amounts of components:
about 51.4 to about 60.6% by weight of the epoxy constituent; about 39 to about 48~ by ~eight of the hardener and flexibilizer portion; and up to about 0.6~ and preferably about 0.4 to about 0.6~ by weight of the coloring agent. The viscosity of the composi-~` 20 tion is about 1000 to about 1700 and preferably about 1300 to about 1700 centipoise at 40C.
The substrate employed is pre~erably a ceramic sub-strate. A ceramic is a product or material manu-~actured by the action of heat on earthy raw materials.
The preferred ceramic substrates include silicon oxides and silicates such as aluminum silicate, and aluminum oxides.
The substrate can include preformed holes through which input/output (I/O) pins can be inserted so as to protrude from one surface of the substrate for insertion into circuit cards or boards. The pins also protrude slightly from the other surface referred to as the backside so as to contact the circuitry on the backside which in turn connects to the integrated circuit chip rnounted on the backside of the substrate.
The chips can be mounted, for instance, by well-known solder techniques.
The present invention is particularly effective for substrates with dimensions along at least one edge thereof which is at least about 30 millimeters long.
This is so since the problem of the above-discussed commercially employed sealing composition concerning cracking becomes significant when using substrates having at least one edge which is at least about 30 millimeters in length. This cracking problem`experi-enced is not so significant when using smaller sub-strates such as those of about 1 square inch and about 28 millimeters on a side. Although cracking does occur with the smaller substrates, the frequency is signi~icantly less than when employing, for instance, a 36 millimeter squaxe substrate as discussed herein-; above. With the larger substrates, the frequency of cracking is at a level which is very unsatisfactory from a commer~ial viewpoint (e.g., about 10-30~
failures). Use o the present invention brings the failure rate down to an acceptable level of 1 to ~%.
.
The pins of the module can be any of the input-output pins well known in the art and need not be discussed herein i-n any great detail. Examples of suitable-pins are goldplated pins, and tin-lead solder coated pins. It has been observed that the compositions of the present invention as compared to the above-discussed commercially employed compositions, result in less film formation on the pins. This is especially helpful with respect to the goldplated pins.
The Figure illustrates a cross-section of a module of the present invention. Numeral 1 illustrates the substra-te through which pins 2 extend and protrude from the topside thereof. Numeral 3 represents .the small portion of the pin protruding on -the backside of the substrate fox carrying curren-t there~o. The integrated circuit chip such as a silicon or polycry-stalline silicon chip is represented by numeral 4 and is attached to substra-te 1 wi-th solder 9. Num~eral 5 represents the potting or encapsulating composition and the approximate level of acceptable "run-in" is shown by 5A. Numeral 6 represents the cap or can.
The cap or can is prefera~ly a metal, for example, aluminum and is employed to protect the backside and especially the chip from mechanical damage. In addi-tion, the metal cap facilitates cooling of the entire module in that heat is conducted thereby. The walls of the cap are closely toleranced with the dimensions of the substrate to provide a close fit. Once the chip is placed inside, the can can be crimped and the coating composition is applied which then adheres the substrate hermetically to the sides of the cap to thereby seal the backside from the surrounding environ-ment. The upstanding walls 7 of the cap 6 are highenough so as the entire thickness of the substrate and the chip therebelow can Eit inside the cap. As is well known, the cap includes stand offs (not shown) upon which the chip carrier (substrate) can rest to prevent the chip from contacting physically with the bottom o-f the inside of the cap. Numeral 8 represents a nozzle or needle for dispensing the composition.
The area of pins to be covered by the potting or en-capsulating composition is generally referred to as the "stand-off" area of the pins. The encapsulating - composition is applied to the module up to the "stand-off" area in order to protect and seal the electrically active portio~s of the module. The coating can be carried out by a liquid dispense coating technique with dispense needles placed abo~e open areas of the substrate with the pins pointing upwards..
After the coating step, the composition is cured by the application of elevated temperatures. The compo-sitions are generally cured at temperatures of about 100 to about 200C for about 1/2 to about 10 hours.
Preferably the curing is a multistage curing process which includes curing at about 100 to about 120C
from about 2 to about 4 hours and then curing at about 150C to about 200C for about 4 more hours. Such curing insures sufficient cross-link density to obtain the desired solvent resistance and other properties.
The pins when desired can be coa~ed with solder between the curing steps or after the second curing step. A
typical solder operation involves coating the pins with a soldering material such as a tin-lead (63-37 eutectic) in a bath at about 580C for a few hours. When a solder operation is emp~oyed, the pins are coated with conven-tional flux composition for the solder. Fluxing compo-sitions act to prevent and remove oxides from the pins during the soldering operation.
~ .
In a typical product prepared according to the present invention, the ceramic is a square of about 1 inch to about 36 millimeters on each side and about 65 mils 5 mils thick. The sealant of the present invention is generally employed in thicknesses of about 10 to about 3~ mils. The clearance between the integrated circuit chip or wafer and bottom of the cap is about 60 mlls.
The following nonlimiting examples are presented to further illustrate the present invention.
Example I
. .
Onto 40 ceramic 36 millimeter modules in a cell is dispensed by liquid dispensing a composition having a ~iscosity of about 1350 CPS at 40C containing about 50 parts by ~leight o~ a diglycidyl ether o~ bisp~enol A
~3~
and epichlorohydrin having an epoxy equivalent weight of 185 to 192 and a viscosity at 25C of 10,000-15,000 CPS available under the trade designation Epon 828;
about 4~ parts by weight of a hardener and flexibiLi~er portion obtained from the 3~ Company and containing 25 to 39~ by weight of hexahydrophthalic anhydride; 50 to 75~ by weight of polyoxypropylene glycol and/or polypropylene glycol, 0. 85-1~ by weight of tertiar~
amine; and minor amounts of hexahydrophthalic acid resulting from -the hydrolysis of the hexahydrophthalic anhydride wherein the hardener and flexibilizer portion has a viscosity of about 900 to 2550 CPS at 25C and an acid number of 3 . 8+ . 2 mg KOH/gram; and about 2~ by weight oE a green coloring agent portion available under the trade designation Hysol, about 80~o of which is Epon 82~ and about 20% of which is chlorinated copper phthalocyamine dye on a titanium dioxide pigment carrier.
The coating thickness about 35 mils. The composition 20 is at 55+ 5C during dispenslng and the module surface is at about 100C during dispensing. The dispensing takes about 10 minutes. The temperature of the coating is raised immediately to about l20C over a 20 minute period starting at 90C due to contact with the sub-strate, and is maintained at about 120C for about 20 minutes.for gelation to occur.
The coating is then cured by heating at about 100C
for 4 hours, followed by heating at about 150C for another 4 hours.
Exam~le II
Example I is repeated with the same composition from the same batch of material. The difference being that the crimping step prlor to coating is somewhat dlfferent.
-~3~9~i ' Exam~le III
Example I is repeated except that the coating composi-tion employs the same batch of material but in the rela-tive amounts currently commercially employed, and in particular employs about 46 percent by weight of Epon 828, about 52 percent by weight of the hardener and flexibilizer portion and about 2% by weight of the coloring agent portion (Hysol)O The composition has a viscosity of 1030 CPS at 40C~
Example IV
Comparison example III is repeated except that the crimping step prior to coating is the one employed in Example II.
Testing of Exam~les I - IV
The 40 modules in each of the above examples are tested for reliability by being placed in a central chamber and subjected to thermal stress cycling from 0-100C for 300 cycles, 3 cycles per hour. The modules are tested before and after thermal stress exposure for seal integrity by leak testing. With respect to examples I and II no leakage of modules was observed. On the other hand 5 modules prepared in accordance wit,h Example III leaked and 1 module prepared in accordance with Example IV leaked. Also none of the modules o~
Example II cracked and only 2 of Example I cracked.
However, 8 modules from Example III and 8 modules ~rom Example IV cracked.
, Example V
Modules coated by the process of Example I with a com-position having the same relative amounts of Epon 828, hardener and flexibili~er portion, and Hysol coloring agent (80% of which is also Epon 828) as employed in Example I are tested for resistance to reversion at 96C and 95% relative humidity and at 85C and 95% rela-tive humidity. The time for failure at 95C is ~138 days ~IL3~
and the time for failure at 85C is greater than 214 days.
Comparison Example VI
. . _ _ _ .... . . _ Example 5 is repeated except that the relative amounts of the ingredients are the same as the current commer-cially employed composition. The time for failure at-90C is 131 days and at 85C is greater than 214 days.
The Shore D hardness of the coating of this example is about 79; whereas, tha-t for Example V is slightly less at about 77.
Example VII
Example V is repeated except that the composition con-tains about 53% by weight of Epon 828, about 45% by weight of the hardener and flexibilizer portion and about 2% by weight of the coloring agent portion, 80%
of which is Epon 828. Therefore the total Epon 828 is about 54.6%. The results obtained are similar to those from Example V. The hardness is about 72.
Example VIII
Example V is repeated except that the composition contains about 58% by weight of Epon 828, about 40%
- by weight of the hardener and flexibilizer portion and abo~t 2% by weight of the coloring agent portion, 80~ of which is Epon 828. The total Epon 828 content thexefore being about 59.6% by weight. The results obtained are similar to those of Example V.
:
Example IX
Example V is repeated except that the composition con-tains about 59% by weight of Epon 828, about 39% by weight of the hardener and flexibilizer portion and about 2~ by weight of the coloring agent portion, 80%
of which is Epon 828. The total Epon 828 content therefore is about 60.6% by weight. The results-obtained ~L~L3~V~
are similar to those of Example 5.
In addit.ion, modules prepared in accordance with Examples V-IX are tested for water permeation at 125 ~2C in saturated water vapor for 130 hours.
The coatin~s of the present invention and that c~r-rently commercially employed have about the same water permeation properties.
~'
SEALING OF INTEGRATED CIRCUIT MODULES
Description Technical Field The present invention is concerned with an integrated circuit module wherein the backside of the substrate which contains the integrated circuit chip(s) is her-metically sealed to a cap by an improved epoxy compo-I sition, and to the improved composition. In addition, the present invention is concerned with the process or hermetically sealing the backside of the substrateof an integrated circuit module by employing certain epoxy compositions. The present invention is particu-larly concerned with those integrated circuit modules which contain a substrate having electrically-conductive pins protruding therefrom and having attached to the backside of the substrate at least one integrated cir-cuit chip, and including a cap or containeE into which the substrate is placed with the backside thereof being covered by the bottom of the cap or container.
.:
Background Art During the preparation of integrated circuit modu'es, certain epoxy compositions have been employed to her-metically seal the backside of the substrate on which is attached at least one integrated circuit chip.
Such compositions are emplOyed to protect and seal the electrically active portions of the module.
In order for a aomposition to be commercially aoceptable `'~
~ ,~.
~ , . ._, ~3~6 for sealing integrated circuit modules, it must possess a number of critical properties. In particular, the composition must be a nonconductor of electricity and must be capable of withstanding degradation due to expo-sure to various chemicals such as organic sol~ents and due to the e~fects of being exposed to the flow of electricity over extended periods of time. In addition, the composition must be resistant to reversion to non-fully cured products under ad~erse conditions of ele-vated temperature and high humidity over extendedperiods of time such as for at least about 10~years to be usable for integrated circuit packages to be employed in modern day computers. The compositions must also possess significant strength characteristics so as to resist deterioration when subjected to mechanical stresses. The compositions should also have good flexi-bility and be able to withstand thermal cycling (i.e., expansion and contraction due to temperature changes) without cracking. The compositions also must be resistant to permeation and diffusion of gases and sol-vents. Moreo~er, the composition must adhere tenaciously to the particular substrate employed.
' Since about 1974, the assignee of t:he present applica-tion, International ~usiness Machines Corporation, has employed a composition with ingredients containing about 47.6% by weight of a bisphenol A - epichlorohydrin epoxy polymer; about 5~% by weight of a hardener and flexibilizer mixture and about 0.4% by weight of a coloring agent. The hardener and flexibilizer mixture contains about 25 to 39~0 of hexahydrophthallc anhydride;
about 50 to about 75% by weight of a polypropylene glycol and/or polyoxypropylene glycol flexibilizer;
about 0.85 to about 1% by weight of a tertiary amine ~e.g., trimethyl amine); and a minor amount of hexa-hydrophthalic acid resulting from hydrolysis of the corresponding anhydride.
.. ... . _ . _ . _ _ . . .. ... _ _ _, _ .. , ~L3~L09~
~he coloring ag~nt employed is generally a mixture of chlorl~ated copper phthalocyanine on a titanium dioxide pigment.
This composition fox the mast part has been qu~te S satisfactory for its intended purpose as a potting or encapsulating composition used to seal the backside of an integrated circuit module or package. For in-stance, the solvent resistance, electrical resistance, I mechanical resistance, and reversion properties are commercially acceptable.
However, the flexibility of this composition is not entirely satisfactory. In addition, this commercially employed composition suffers from the disadvantage of insufficient resistance to cracking due to thermal cycling. When cracking occurs, substances in the sur-rounding environment (e.g., moisture) can come into contact with the backside of the module and cause problems such as corrosion of electrically active parts of the module resulting in reduced reliability. Accord-ingly, when cracking of the coating occurs,~the moduleas such is not used. The craclcing due to thermal stress became quite pronounced when the length of the sides of the modules was increased above 28 millimeters such as to about 36 millimeters. For instance, modules of 28 millimeters or less on a side have failures of about 1 to 4% due to thermal cracking when employing the above commercial composition. Failures in this range are commercially tolerable. ~owever, upon increasing the substrate size to at leas~ about 36 millimeters on a side, the failures increased to between 10 and 30% with the above compositions. These rates of failure are not commercially acceptable.
Accordingly, it is an object of the present invention ~' to provide a sealing composition which is less suscep-tible to thermal stress cracking than the now c~mmercially EN~79007 employed compositions discussed hereinabove~ A fur-ther object of the present invention is to provide a sealing composition which is more flexible than the above mentioned commercially employed epo~y composi-s tion. A major difficulty in overcoming these .defi-ciencies and problems is not to cause a deterioration in the other essential properties for a sealant to be employed in the preparation of integrated circuits.
Surprisingly, the present invention provides for at least as good mechanical, electrical, and chemical resistances as achieved in the above-discussed commer-cially acceptable composition and at least as good if not better reversion properties while at the same time increasing the ability to withstand thermal cycling without cracking and increasing the flexibility.
The increased flexibility and increased ability to withstand thermal cycling are quite surprising since ; the present invention employs less of the hardener and ; flexibilizer mixture than is used in the above-discussed commeLcially employed composition.
; Another problem experienced with the above-discussed commercially employed composition is referred to as - "run-in". "Run-in" refers to the flow of the composi-tion downward into the cap or can used to cover the backside of the substrate. This occurs at space gaps at the corners between the substrate which generally has a slightly rounded edge and the cap or can which are generally square. If the composition flows com-pletely to the underside of the substrate, then problems in reliahility could be caused by destruction of solder joints u~on thermal expansion. This problem has been compensated for by closely fitting the cap or can to the substrate such as by crimping the cap or can.
The present invention significantly reduces, if.not elimlnates, this problem of run-in. The compositions of the present invention resist flow downward to an undesired extent to the bot-tom of the cap or can, while at the same time flowing vertically when dis~
pensed to cover the entire substrate and contact -the upstanding walls of the cap or can adjacent the sub-stra-te to form the seal. Accordingly, the use of the present invention makes it possible to tolerate larger gaps at the corners between the substrate and cap; and thereby, making it possible to use less crimping than previously re~uired. Reduced crimping in turn reduces mechanical stress on the back seal compositions which are used to coat the integrated circuit chip.
Disclosure of the Invention .. . .... _ .
The present invention is concerned with. an integrated circuit module containing a substrate having electrically-conductive pins protruding therefrom, and having attached to the backside thereof at least one integrated circuit chip. The backside of the substrate is contained within a cap or can and is hermetically sealed thereto by a composition applied over the exposed surface of the substrate and over a portion of the height of the pins. The composition contains about 51.4 to about 60.6~ by weight of an epoxy which consists essentially of a bisphenol A -epichlorohydrin epoxy polymer; about 39 to about 48~
by weight of a hardener and flexibilizer portion; and up to about 0.6~ by weight of a coloring agent. The bisphenol A - epichlorohydrin polymer has an epoxy e~uivalent weight of about 1 ao to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25C.
The hardener and flexibilizer portion contains about 15 to about 49% by weight of an anhydride hardeneri about 40 to about 85% by weight of a polyalkylene glycol and/or a pol~oxyalkylene gl~col ~le~ibili~er;
up to about 1~ of a tertiary amine catalyst for the epoxy; and minor amount of an acid resulting from the hydrolysis of the corresponding anhydride hardener.
The maximum amount of the acid is such that the acid number of the hardener and flexibili~er portion does not exceed about 4.0 mg KOH/gram.
The polyalkylene glycols are polyoxyalkylene glycols having molecular weights so that the viscosity of the hardener and flexibilizer portion is about 900 to about 2500 centipoise at 25C.
The present invention is also concerned with the above-discussed composition.
Furthermore the present invention is concerned with a process for hermetically sealing the backside oE
the substrate of an integrated circuit module. The process includes providing a substrate having electrically-conductive pins protruding therefrom and having attached to the backside thereof at least one integrated circuit chip. The substrate with the chip attached thereto is placed into a cap or can wherein the backside of the substrate is covered by the cap or can. The composition discussed hereinabove is provided over the e~posed surface o~ the substrate and a portion of the height of the pins and is then cured in order to hermetically seal the backside of the substrate within the gap or can.
The Figure is a schematic cross section of a module in accordance with the present invention.
~1 The present invention is also generally discussed in IBM*Technical Disclosure Bulletin Volume 20 No. 10 `` March 1978 prepared on behalf of the inventors of this application.
*Registered Trade Mark , ~ EN979007 , _ , _ ................ ..
~L3~
Bes-t Mocle for C2rryin~ out Invention The epoxy polymers employed according to the present invention are diglycidyl ethers of bisphenol A - ~
epichlorohydrin. The epoxy polymer component can also contain minor amounts (e.g., up to about 5~ by weight) of other types of epoxides such as phenyl-glycidyl ether.
The epoxy polymers employed according to the present invention have an epoxy equivalent weight of about 180 to about 210 and should have a viscosity of about 6,500 to about 22,500 centipoise at 25C. Some exampIes o~
epoxy polymers suitable for the present invention ~hich are commercially available from Shell Oil in-15 clude Epon*820, Epon g26, Epon 830, and Epon 828.
; Epon 82~ is a diglycidyl ether of bisphenol-A - epi-chlorohydrin having an epoxy equivalent weight of 185 ~ to 192 and viscosity of 10,000 to 15,000 CPS at 25C.
- ~pon 820 is a mixture of Epon 828 with about 2 to about 5% by weight of phenyl glycidyl ether, and has ; an epoxy equivalent weight of 180 to 195 an~ a vis- ,~
cosity of 6,500 to 10,000 CPS at 25C. Epon 826 is a diglycidyl ethex of bisphenol A - epichlorohydrin ~ . .
~ having an epoxy equivalent weight of 180-188 and a -~ 25 viscosity of 6,500 to 9,500 CPS at 25C. Epon 830 is a diglycidyl ether of bisphenol A - epichlorohydrin having an epoxy equivalent weight of 190 to 210 and a viscosity of 15,000 to 22,500 CPS at 25C. , The hardener and flexibilizer portion of the comp,osi-tion incLudes an anhydride hardener or mi,~ture of anhydrides for the epoxy, and a polyalkylene glycol and/or polyoxyalkylene glycol flexibilizer. The hardener ,and fle~ibilizer portion can also include a tertiary amine catalyst for the epoxy and minor amounts of acid(s) which can result from the hydrolysis Df the *Trade Mark " ... . . . ., . .. . _ ... ... _____ . .. . . .. _. _ .-- _ . . ._ . _ ._.. _, ~
"
corresponding anhydride(s), By includiny the above component in the hardener and flexibilizer pOrtiQn, it is not intended to mean that these must be premixed together separately prior to admixing with the epoxy.
These components have been recited in this manner so as to facilitate the calculations and disclosure with respect to the relative amounts of ingredients which must be employed.
The hardener is an anhydride such as nadic methyl anhy-dride and preferably a phthalic type anhydride such as hexahydrophthalic anhydride and tetrahydrophthalic anhydride. ~ixtures of anhydrides can be employed if desired. The anhydride is present in amount of about 15 to about 49% by weight and preferably 25 to about ;~ 15 39% by weight based upon the weight of the total weight of the anhydride, flexibilizer, tertiary amine and acid in the hardener and flexibilizer portion of the composition.
The flexibilizer is a polyalkylene glycol and/or poly-oxyalkylene glycol which can be represented by the formula:
HO-R-O-[-R O-]n-R-OH
wherein R is a divalent saturated aliphatic hydrocax-bon moiety selected from the group of ethylene, propylene,~butylene and mix~ures thereof, These groups can be straight or branched chained, ~'` , Mixtures of these glycols can be employed if desired.
The n is 0 or an integer such that the molecular weigh-t thereof in conjunction with the amount used is such that the viscosity of the hardener and flexibilizer portion is about 900 to about 2,500 centipoise at 25C, Examples of some suitable glycols include polyethylene glycol, polyoxyethylene glycol, polypropylene glycol, polyoxypropylene glycol, polyoxyethyleneoxypropylene , 35 glycol, and polybutylene glycol. The preferred ~lycols are polypropylene glycol and polyoxypropylene glycol.
The glycol or glycols are present in amounts of about 40 to about 85% and preferably about 50 to about 75~
by weight based upon the total weight of the h~rdener and flexibilizer portion of the composition.
A ter~iary amine curing agent musk also be employed.
The preferred tertiary amines include the saturated aliphatic monoamines such as trimethyl amine and triethyl amine. The tertiary amine can be employed in amounts of 0.1 to about 1% and preferably about 0.85 to about 1~ by weight based upon the total weight of the hardener and flexibilizer portion of the composition.
In addition, minor quantities of acid(s), e.g., up to about 1% or more based on the weight of the hardener and flexibilizer portion, might be presbnt due to hy-drolysis of the corresponding anhydride(s). The maxi-mum amount of acid is such that the acid number of the hardener and flexibilizer por~ion not exceed about 4.0 mg KOH/gram.
: , .
The compositions can also include a coloring agent.
` Such is employed as a visual means to determine whether there is contamination of the composition on the parts of the pins which are not to be coated. The presence ; of the coloring agent also enhances inspection to ; 25 determine whether the composition has adequately covered the substrate surface and~joined to the cap or can.
.
The preferred coloring agents lnclude the phthalocya-nine dyes and most preferably are mixtures of chlori-nated copper phthalocyanine (a green dye) andtitanium dioxide pigment. Such is commercially avail-able in the form of a mixture with a bisphenol A -epichlorohydrin epoxy polymer of the type employed in ~3g~6 the present invention under the trade designation Hysol. The commercially available Hysol compositions contain about 20~ by weight of the chlorinated or polychloro copper phthalocyanine and titanium dioxide mlxture and about a o% by weight of the bisphenol A -epichlorohydrin epoxy resin (Shell Epon 828). Mixtures of coloring agents can be employed if desired.
- If it is desired to provide a clear, transparent com-position, then no coloring agent would be employed.
The compositions employed according to the present invention, in order to obtain the improved results discussed hereinabove without a concomitant deteriora-tion in the other essential characteristics, must include the following relative amounts of components:
about 51.4 to about 60.6% by weight of the epoxy constituent; about 39 to about 48~ by ~eight of the hardener and flexibilizer portion; and up to about 0.6~ and preferably about 0.4 to about 0.6~ by weight of the coloring agent. The viscosity of the composi-~` 20 tion is about 1000 to about 1700 and preferably about 1300 to about 1700 centipoise at 40C.
The substrate employed is pre~erably a ceramic sub-strate. A ceramic is a product or material manu-~actured by the action of heat on earthy raw materials.
The preferred ceramic substrates include silicon oxides and silicates such as aluminum silicate, and aluminum oxides.
The substrate can include preformed holes through which input/output (I/O) pins can be inserted so as to protrude from one surface of the substrate for insertion into circuit cards or boards. The pins also protrude slightly from the other surface referred to as the backside so as to contact the circuitry on the backside which in turn connects to the integrated circuit chip rnounted on the backside of the substrate.
The chips can be mounted, for instance, by well-known solder techniques.
The present invention is particularly effective for substrates with dimensions along at least one edge thereof which is at least about 30 millimeters long.
This is so since the problem of the above-discussed commercially employed sealing composition concerning cracking becomes significant when using substrates having at least one edge which is at least about 30 millimeters in length. This cracking problem`experi-enced is not so significant when using smaller sub-strates such as those of about 1 square inch and about 28 millimeters on a side. Although cracking does occur with the smaller substrates, the frequency is signi~icantly less than when employing, for instance, a 36 millimeter squaxe substrate as discussed herein-; above. With the larger substrates, the frequency of cracking is at a level which is very unsatisfactory from a commer~ial viewpoint (e.g., about 10-30~
failures). Use o the present invention brings the failure rate down to an acceptable level of 1 to ~%.
.
The pins of the module can be any of the input-output pins well known in the art and need not be discussed herein i-n any great detail. Examples of suitable-pins are goldplated pins, and tin-lead solder coated pins. It has been observed that the compositions of the present invention as compared to the above-discussed commercially employed compositions, result in less film formation on the pins. This is especially helpful with respect to the goldplated pins.
The Figure illustrates a cross-section of a module of the present invention. Numeral 1 illustrates the substra-te through which pins 2 extend and protrude from the topside thereof. Numeral 3 represents .the small portion of the pin protruding on -the backside of the substrate fox carrying curren-t there~o. The integrated circuit chip such as a silicon or polycry-stalline silicon chip is represented by numeral 4 and is attached to substra-te 1 wi-th solder 9. Num~eral 5 represents the potting or encapsulating composition and the approximate level of acceptable "run-in" is shown by 5A. Numeral 6 represents the cap or can.
The cap or can is prefera~ly a metal, for example, aluminum and is employed to protect the backside and especially the chip from mechanical damage. In addi-tion, the metal cap facilitates cooling of the entire module in that heat is conducted thereby. The walls of the cap are closely toleranced with the dimensions of the substrate to provide a close fit. Once the chip is placed inside, the can can be crimped and the coating composition is applied which then adheres the substrate hermetically to the sides of the cap to thereby seal the backside from the surrounding environ-ment. The upstanding walls 7 of the cap 6 are highenough so as the entire thickness of the substrate and the chip therebelow can Eit inside the cap. As is well known, the cap includes stand offs (not shown) upon which the chip carrier (substrate) can rest to prevent the chip from contacting physically with the bottom o-f the inside of the cap. Numeral 8 represents a nozzle or needle for dispensing the composition.
The area of pins to be covered by the potting or en-capsulating composition is generally referred to as the "stand-off" area of the pins. The encapsulating - composition is applied to the module up to the "stand-off" area in order to protect and seal the electrically active portio~s of the module. The coating can be carried out by a liquid dispense coating technique with dispense needles placed abo~e open areas of the substrate with the pins pointing upwards..
After the coating step, the composition is cured by the application of elevated temperatures. The compo-sitions are generally cured at temperatures of about 100 to about 200C for about 1/2 to about 10 hours.
Preferably the curing is a multistage curing process which includes curing at about 100 to about 120C
from about 2 to about 4 hours and then curing at about 150C to about 200C for about 4 more hours. Such curing insures sufficient cross-link density to obtain the desired solvent resistance and other properties.
The pins when desired can be coa~ed with solder between the curing steps or after the second curing step. A
typical solder operation involves coating the pins with a soldering material such as a tin-lead (63-37 eutectic) in a bath at about 580C for a few hours. When a solder operation is emp~oyed, the pins are coated with conven-tional flux composition for the solder. Fluxing compo-sitions act to prevent and remove oxides from the pins during the soldering operation.
~ .
In a typical product prepared according to the present invention, the ceramic is a square of about 1 inch to about 36 millimeters on each side and about 65 mils 5 mils thick. The sealant of the present invention is generally employed in thicknesses of about 10 to about 3~ mils. The clearance between the integrated circuit chip or wafer and bottom of the cap is about 60 mlls.
The following nonlimiting examples are presented to further illustrate the present invention.
Example I
. .
Onto 40 ceramic 36 millimeter modules in a cell is dispensed by liquid dispensing a composition having a ~iscosity of about 1350 CPS at 40C containing about 50 parts by ~leight o~ a diglycidyl ether o~ bisp~enol A
~3~
and epichlorohydrin having an epoxy equivalent weight of 185 to 192 and a viscosity at 25C of 10,000-15,000 CPS available under the trade designation Epon 828;
about 4~ parts by weight of a hardener and flexibiLi~er portion obtained from the 3~ Company and containing 25 to 39~ by weight of hexahydrophthalic anhydride; 50 to 75~ by weight of polyoxypropylene glycol and/or polypropylene glycol, 0. 85-1~ by weight of tertiar~
amine; and minor amounts of hexahydrophthalic acid resulting from -the hydrolysis of the hexahydrophthalic anhydride wherein the hardener and flexibilizer portion has a viscosity of about 900 to 2550 CPS at 25C and an acid number of 3 . 8+ . 2 mg KOH/gram; and about 2~ by weight oE a green coloring agent portion available under the trade designation Hysol, about 80~o of which is Epon 82~ and about 20% of which is chlorinated copper phthalocyamine dye on a titanium dioxide pigment carrier.
The coating thickness about 35 mils. The composition 20 is at 55+ 5C during dispenslng and the module surface is at about 100C during dispensing. The dispensing takes about 10 minutes. The temperature of the coating is raised immediately to about l20C over a 20 minute period starting at 90C due to contact with the sub-strate, and is maintained at about 120C for about 20 minutes.for gelation to occur.
The coating is then cured by heating at about 100C
for 4 hours, followed by heating at about 150C for another 4 hours.
Exam~le II
Example I is repeated with the same composition from the same batch of material. The difference being that the crimping step prlor to coating is somewhat dlfferent.
-~3~9~i ' Exam~le III
Example I is repeated except that the coating composi-tion employs the same batch of material but in the rela-tive amounts currently commercially employed, and in particular employs about 46 percent by weight of Epon 828, about 52 percent by weight of the hardener and flexibilizer portion and about 2% by weight of the coloring agent portion (Hysol)O The composition has a viscosity of 1030 CPS at 40C~
Example IV
Comparison example III is repeated except that the crimping step prior to coating is the one employed in Example II.
Testing of Exam~les I - IV
The 40 modules in each of the above examples are tested for reliability by being placed in a central chamber and subjected to thermal stress cycling from 0-100C for 300 cycles, 3 cycles per hour. The modules are tested before and after thermal stress exposure for seal integrity by leak testing. With respect to examples I and II no leakage of modules was observed. On the other hand 5 modules prepared in accordance wit,h Example III leaked and 1 module prepared in accordance with Example IV leaked. Also none of the modules o~
Example II cracked and only 2 of Example I cracked.
However, 8 modules from Example III and 8 modules ~rom Example IV cracked.
, Example V
Modules coated by the process of Example I with a com-position having the same relative amounts of Epon 828, hardener and flexibili~er portion, and Hysol coloring agent (80% of which is also Epon 828) as employed in Example I are tested for resistance to reversion at 96C and 95% relative humidity and at 85C and 95% rela-tive humidity. The time for failure at 95C is ~138 days ~IL3~
and the time for failure at 85C is greater than 214 days.
Comparison Example VI
. . _ _ _ .... . . _ Example 5 is repeated except that the relative amounts of the ingredients are the same as the current commer-cially employed composition. The time for failure at-90C is 131 days and at 85C is greater than 214 days.
The Shore D hardness of the coating of this example is about 79; whereas, tha-t for Example V is slightly less at about 77.
Example VII
Example V is repeated except that the composition con-tains about 53% by weight of Epon 828, about 45% by weight of the hardener and flexibilizer portion and about 2% by weight of the coloring agent portion, 80%
of which is Epon 828. Therefore the total Epon 828 is about 54.6%. The results obtained are similar to those from Example V. The hardness is about 72.
Example VIII
Example V is repeated except that the composition contains about 58% by weight of Epon 828, about 40%
- by weight of the hardener and flexibilizer portion and abo~t 2% by weight of the coloring agent portion, 80~ of which is Epon 828. The total Epon 828 content thexefore being about 59.6% by weight. The results obtained are similar to those of Example V.
:
Example IX
Example V is repeated except that the composition con-tains about 59% by weight of Epon 828, about 39% by weight of the hardener and flexibilizer portion and about 2~ by weight of the coloring agent portion, 80%
of which is Epon 828. The total Epon 828 content therefore is about 60.6% by weight. The results-obtained ~L~L3~V~
are similar to those of Example 5.
In addit.ion, modules prepared in accordance with Examples V-IX are tested for water permeation at 125 ~2C in saturated water vapor for 130 hours.
The coatin~s of the present invention and that c~r-rently commercially employed have about the same water permeation properties.
~'
Claims (22)
1. An integrated circuit module containing a substrate having electrically-conductive pins protruding therefrom, and having attached to the backside thereof at least one integrated circuit chip where-in the improvement comprises providing a hermetical seal of the backside of the substrate contained within a cap with a composition over the substrate and a portion of the height of the pins containing:
(A) about 51.4 to about 60.6% by weight of an epoxy of at least about 95% of which being a diglycidyl ether of bisphenol A and epichloro-hydrin, having an epoxy equivalent weight of about 180 to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25°c;
(B) about 39 to about 48% by weight of a hardener and flexibilizer portion containing (1) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(2) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated ali-phatic hydrocarbon moiety selected from the group of ethylene, propylene, buty-lene, and mixtures thereof; and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of the har-dener and flexibilizer portion is about 900 to about 2500 centipoise at 25°C;
(3) 0.1 to about 1% by weight of a tertiary amine curing agent for the epoxy; and (4) 0 to minor amounts of acid resulting from hydrolysis of said anhydride; where-in said minor amount is such that the acid number of the hardener and flexi-bilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of B(1), B(2) and B(3) and B(4) are based upon the total of B(1), B(2), B(3) and B(4) of the hardener and flexibilizer portion; and (C) 0 to about 0.6% by weight of a coloring agent.
(A) about 51.4 to about 60.6% by weight of an epoxy of at least about 95% of which being a diglycidyl ether of bisphenol A and epichloro-hydrin, having an epoxy equivalent weight of about 180 to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25°c;
(B) about 39 to about 48% by weight of a hardener and flexibilizer portion containing (1) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(2) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated ali-phatic hydrocarbon moiety selected from the group of ethylene, propylene, buty-lene, and mixtures thereof; and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of the har-dener and flexibilizer portion is about 900 to about 2500 centipoise at 25°C;
(3) 0.1 to about 1% by weight of a tertiary amine curing agent for the epoxy; and (4) 0 to minor amounts of acid resulting from hydrolysis of said anhydride; where-in said minor amount is such that the acid number of the hardener and flexi-bilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of B(1), B(2) and B(3) and B(4) are based upon the total of B(1), B(2), B(3) and B(4) of the hardener and flexibilizer portion; and (C) 0 to about 0.6% by weight of a coloring agent.
2. The module of claim 1 wherein said epoxy is essen-tially a diglycidyl ether of bisphenol A and epichlorohydrin.
3. The module of claim 1 wherein said hardener and flexibilizer portion contains about 25 to about 39% by weight of said hardener; and about 50 to about 75% by weight of said polyglycol flexibilizer.
4. The module of claim 3 wherein said hardener and flexibilizer portion contains about 0.85 to about 1% by weight of a tertiary amine curing agent.
5. The module of claim l wherein said hardener is a phthalic anhydride.
6. The module of claim 1 wherein said hardener is hexahydrophthalic anhydride.
7. The module of claim 1 or claim 6 wherein said polyglycol is polypropylene glycol or polyoxypro-pylene glycol or mixtures thereof.
8. The module of claim 7 wherein said amine is trimethyl amine.
9. The integrated circuit module of claim 1 wherein said coloring agent is employed in amounts from about 0.4 to about 0.6% by weight.
10. The integrated circuit module of claim 1 wherein said substrate is at least about 30 millimeters along at least one edge thereof.
11. The integrated circuit module of claim 1 wherein said substrate is at least about 36 millimeters along at least one edge thereof.
12. The integrated circuit module of claim 1 wherein said substrate is a ceramic.
13. The integrated circuit module of claim 1 wherein said cap is a metal.
14. The integrated circuit module of claim 1 wherein said cap is aluminum.
15. The integrated circuit module of claim 1 wherein said pins are solder coated pins or goldplated pins.
16. The integrated circuit module of claim 9 wherein said coloring agent includes a copper phthalo-cyanine dye.
17. The module of claim 9 wherein said coloring agent is a chlorinated copper phthalocyanine dye mixed with titanium dioxide.
18. The integrated circuit module of claim 1 wherein said composition contains about 51.6% by weight of a bisphenol A - epichlorohydrine polymer; about 48% by weight of said hardener and flexibilizer portion and about 0.4% by weight of a coloring agent.
19. The integrated circuit module of claim 1 wherein said composition contains about 54.6% by weight of a bisphenol A - epichlorohydrin epoxy polymer;
about 45% by weight of said hardener and flexibi-lizer portion and about 0.4% by weight of a color-ing agent.
about 45% by weight of said hardener and flexibi-lizer portion and about 0.4% by weight of a color-ing agent.
20. The integrated circuit module of claim 1 wherein said composition contains about 60.6% by weight of a bisphenol A - epichlorohydrin polymer; about 39% by weight of said hardener and flexibilizer portion and about 0.4% by weight of a dye.
21. A sealing composition consisting essentially of A) about 51.4 to about 60.6% by weight of an epoxy at least about 95% of which being a diglycidyl ether of bisphenol A and epichloro-hydrin, having an epoxy equivalent weight of about 180 to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25°C;
(B) about 39 to about 48% by weight of a hardener and flexibilizer portion containing (1) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(2) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated ali-phatic hydrocarbon moiety selected from the group of ethylene, propylene, buty-lene, and mixtures thereof; and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of' the har-dener and flexibilizer portion is about 900 to about 2500 centipoise at 25°C;
(3) 0.1 to about 1% by weight of a tertiary curing agent for the epoxy; and (4) 0 to minor amounts of acid resulting from hydrolysis of said anhydride; wherein said minor amount is such that the acid number of the hardener and flexibilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of B(1), B(2), B(3) and B(4) are based upon the total of B(1), B(2), B(3) and B(4) of the hardener and flexibilizer portion; and (C) 0 to about 0.6% by weight of a coloring agent.
(B) about 39 to about 48% by weight of a hardener and flexibilizer portion containing (1) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(2) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated ali-phatic hydrocarbon moiety selected from the group of ethylene, propylene, buty-lene, and mixtures thereof; and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of' the har-dener and flexibilizer portion is about 900 to about 2500 centipoise at 25°C;
(3) 0.1 to about 1% by weight of a tertiary curing agent for the epoxy; and (4) 0 to minor amounts of acid resulting from hydrolysis of said anhydride; wherein said minor amount is such that the acid number of the hardener and flexibilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of B(1), B(2), B(3) and B(4) are based upon the total of B(1), B(2), B(3) and B(4) of the hardener and flexibilizer portion; and (C) 0 to about 0.6% by weight of a coloring agent.
22. A process for hermetically sealing the backside of the substrate of an integrated circuit module which comprises.
(A) providing a substrate having electrically-conductive pins protruding therefrom; and having attached to the backside thereof at least one integrated circuit chip;
(B) placing said substrate into a cap wherein the backside of said substrate is covered by said cap;
(C) providing a composition over the exposed sur-face of the substrate and a portion of the height of the pins wherein said composition, contains (1) about 51.4 to about 60.6% by weight of an epoxy at least about 95% of which being a diglycidyl ether of bisphenol and epichlorohydrin, having an epoxy equivalent weight of about 180 to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25°C;
(2) about 39 to about 48% by weight of a hardener and flexibilizer portion con-taining (a) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(b) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated aliphatic hydrocarbon moiety selected from the group of ethylene, propy-lene, butylene, and mixtures thereof;
and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of the hardener and flexi-bilizer portion is about 900 to about 2500 centipoise at 25°C;
(c) 0.1 to about 1% by weight of a ter-tiary curing agent for the epoxy; and (d) 0 to minor amounts of acid resulting from hydrolysis of said anhydride;
wherein said minor amount is such that the acid number of the hardener and flexibilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of 2(a), 2(b), 2(c) and 2(d) are based upon the total of 2(a), 2(b), 2(c) and 2(d) of the hardener and flexibilizer portion; and (3) 0 to about 0. 6% by weight of a coloring agent; and (D) curing said composition to hermetically seal the backside of said substrate within said cap.
(A) providing a substrate having electrically-conductive pins protruding therefrom; and having attached to the backside thereof at least one integrated circuit chip;
(B) placing said substrate into a cap wherein the backside of said substrate is covered by said cap;
(C) providing a composition over the exposed sur-face of the substrate and a portion of the height of the pins wherein said composition, contains (1) about 51.4 to about 60.6% by weight of an epoxy at least about 95% of which being a diglycidyl ether of bisphenol and epichlorohydrin, having an epoxy equivalent weight of about 180 to about 210 and a viscosity of about 6,500 to about 22,500 centipoise at 25°C;
(2) about 39 to about 48% by weight of a hardener and flexibilizer portion con-taining (a) about 15 to about 49% by weight of an anhydride hardener for said epoxy;
(b) about 40 to about 85% by weight of a polyglycol flexibilizer represented by the formula:
HO-R-O-[-R-O-]?-R-OH
wherein R is a divalent saturated aliphatic hydrocarbon moiety selected from the group of ethylene, propy-lene, butylene, and mixtures thereof;
and wherein n is 0 or an integer such that the molecular weight of said flexibilizer in conjunction with the amount employed is such that the viscosity of the hardener and flexi-bilizer portion is about 900 to about 2500 centipoise at 25°C;
(c) 0.1 to about 1% by weight of a ter-tiary curing agent for the epoxy; and (d) 0 to minor amounts of acid resulting from hydrolysis of said anhydride;
wherein said minor amount is such that the acid number of the hardener and flexibilizer portion does not exceed about 4.0 mg KOH/gram; and wherein the amounts of 2(a), 2(b), 2(c) and 2(d) are based upon the total of 2(a), 2(b), 2(c) and 2(d) of the hardener and flexibilizer portion; and (3) 0 to about 0. 6% by weight of a coloring agent; and (D) curing said composition to hermetically seal the backside of said substrate within said cap.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US016,034 | 1979-02-27 | ||
| US06/016,034 US4233620A (en) | 1979-02-27 | 1979-02-27 | Sealing of integrated circuit modules |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1134096A true CA1134096A (en) | 1982-10-19 |
Family
ID=21775024
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA341,841A Expired CA1134096A (en) | 1979-02-27 | 1979-12-13 | Sealing of integrated circuit modules |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4233620A (en) |
| CA (1) | CA1134096A (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4349831A (en) * | 1979-09-04 | 1982-09-14 | General Electric Company | Semiconductor device having glass and metal package |
| US4312116A (en) * | 1980-04-14 | 1982-01-26 | International Business Machines Corporation | Method of sealing an electronic module in a cap |
| US4410647A (en) * | 1980-11-28 | 1983-10-18 | International Business Machines Corporation | Epoxy composition and sealing of integrated circuit modules therewith |
| DE3129756A1 (en) * | 1981-07-28 | 1983-02-17 | Siemens AG, 1000 Berlin und 8000 München | ELECTRICAL COMPONENT, COMPONENT GROUP OR INTEGRATED CIRCUIT INSERTED IN A CUP |
| US4818812A (en) * | 1983-08-22 | 1989-04-04 | International Business Machines Corporation | Sealant for integrated circuit modules, polyester suitable therefor and preparation of polyester |
| US4514752A (en) * | 1984-04-10 | 1985-04-30 | International Business Machines Corporation | Displacement compensating module |
| US4632295A (en) * | 1985-08-12 | 1986-12-30 | International Business Machines Corporation | Reduction atmosphere workpiece joining |
| DE3822167A1 (en) * | 1988-06-30 | 1990-02-08 | Liess Hans Dieter Prof Dr Ing | Light barrier |
| US5028984A (en) * | 1988-11-04 | 1991-07-02 | International Business Machines Corporation | Epoxy composition and use thereof |
| US5019409A (en) * | 1989-01-27 | 1991-05-28 | Microelectronics And Computer Technology Corporation | Method for coating the top of an electrical device |
| US5098864A (en) * | 1989-11-29 | 1992-03-24 | Olin Corporation | Process for manufacturing a metal pin grid array package |
| US4960634A (en) * | 1990-03-14 | 1990-10-02 | International Business Machines Corporation | Epoxy composition of increased thermal conductivity and use thereof |
| US5196251A (en) * | 1991-04-30 | 1993-03-23 | International Business Machines Corporation | Ceramic substrate having a protective coating thereon and a method for protecting a ceramic substrate |
| JPH07169872A (en) * | 1993-12-13 | 1995-07-04 | Fujitsu Ltd | Semiconductor device and manufacture thereof |
| US5548486A (en) * | 1994-01-21 | 1996-08-20 | International Business Machines Corporation | Pinned module |
| US5567984A (en) * | 1994-12-08 | 1996-10-22 | International Business Machines Corporation | Process for fabricating an electronic circuit package |
| US5878483A (en) * | 1995-06-01 | 1999-03-09 | International Business Machines Corporation | Hammer for forming bulges in an array of compliant pin blanks |
| US6974765B2 (en) * | 2001-09-27 | 2005-12-13 | Intel Corporation | Encapsulation of pin solder for maintaining accuracy in pin position |
| KR100559927B1 (en) | 2004-12-09 | 2006-03-13 | 서울반도체 주식회사 | Epoxy resin composite for sealing a light emitting diode and light emitting device employing the same |
| DE102013211090A1 (en) * | 2013-06-14 | 2014-12-18 | Robert Bosch Gmbh | Detection system for detecting a solder joint |
| US20220108930A1 (en) * | 2020-10-07 | 2022-04-07 | Murata Manufacturing Co., Ltd. | Electronic component with metallic cap |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3311589A (en) * | 1962-12-20 | 1967-03-28 | Gen Electric | Epoxy resin compositions cured with reaction products of dicarboxylic anhydrides, aliphatic diols and tertiary amines |
| US3431237A (en) * | 1967-03-27 | 1969-03-04 | Dow Chemical Co | Method of curing epoxy resins |
| BE790021A (en) * | 1971-10-14 | 1973-04-12 | Westinghouse Electric Corp | IMPROVEMENTS IN OR RELATIVE TO RESIN COMPOSITIONS |
-
1979
- 1979-02-27 US US06/016,034 patent/US4233620A/en not_active Expired - Lifetime
- 1979-12-13 CA CA341,841A patent/CA1134096A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4233620A (en) | 1980-11-11 |
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