CA2072727A1 - Copper-based paste containing copper aluminate, for microstructural and shrinkage control of copper-filled vias - Google Patents
Copper-based paste containing copper aluminate, for microstructural and shrinkage control of copper-filled viasInfo
- Publication number
- CA2072727A1 CA2072727A1 CA 2072727 CA2072727A CA2072727A1 CA 2072727 A1 CA2072727 A1 CA 2072727A1 CA 2072727 CA2072727 CA 2072727 CA 2072727 A CA2072727 A CA 2072727A CA 2072727 A1 CA2072727 A1 CA 2072727A1
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- Canada
- Prior art keywords
- copper
- paste
- particles
- aluminate
- sintering
- 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.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
- H05K1/092—Dispersed materials, e.g. conductive pastes or inks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
- H01L21/486—Via connections through the substrate with or without pins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/498—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers
- H01L23/49866—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers characterised by the materials
- H01L23/49883—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers characterised by the materials the conductive materials containing organic materials or pastes, e.g. for thick films
-
- 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
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- 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
- H01L2924/095—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00 with a principal constituent of the material being a combination of two or more materials provided in the groups H01L2924/013 - H01L2924/0715
- H01L2924/097—Glass-ceramics, e.g. devitrified glass
- H01L2924/09701—Low temperature co-fired ceramic [LTCC]
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/46—Manufacturing multilayer circuits
- H05K3/4611—Manufacturing multilayer circuits by laminating two or more circuit boards
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/901—Printed circuit
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
- Y10T428/24917—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including metal layer
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
- Y10T428/252—Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31678—Of metal
Abstract
COPPER-BASED PASTE CONTAINING COPPER ALUMINATE
FOR MICROSTRUCTURAL AND SHRINKAGE CONTROL
OF COPPER-FILLED VIAS
ABSTRACT OF THE INVENTION
A copper-based paste is disclosed for filling vias in, and forming conductive surface patterns on, ceramic substrate packages for semiconductor chip devices. The paste contains copper aluminate powder in proper particle size and weight proportion to achieve grain size and shrinkage control of the via and thick film copper produced by sintering. The shrinkage of the copper material during sintering is closely matched to that of the ceramic substrate.
FOR MICROSTRUCTURAL AND SHRINKAGE CONTROL
OF COPPER-FILLED VIAS
ABSTRACT OF THE INVENTION
A copper-based paste is disclosed for filling vias in, and forming conductive surface patterns on, ceramic substrate packages for semiconductor chip devices. The paste contains copper aluminate powder in proper particle size and weight proportion to achieve grain size and shrinkage control of the via and thick film copper produced by sintering. The shrinkage of the copper material during sintering is closely matched to that of the ceramic substrate.
Description
Fl9-90--027 l 2~37~
COPPER-BASED PASTE CONTAINING COPPER ALUMI_ATE
E'OR_MICROSTRUCTURAL AND_SHRINKAGE CO T OL
OF COPPER-FILLED_~iIAS
Ba~ground of the_Inventlon The present invention generally relates to copper-filled vias in ceramic substrates and, more particularly, to a copper-based paste containing copper aluminate powder in proper particle size and weight proportion for grain size and shrinkage control of the via and thick film copper produced by sintering.
The use of copper-filled vias in ceramic substrates and sintering processes for producing them are well known in the semiconductor packaging art as taught, for example, in U.S. Patent 4,234,367, issued on Nov. 18, 1980 to Lester W. Herron et al. and assigned to the present assignee. Recently, more interest has been focused on the associated problems of the disparity in shrinkage rates between copper and ceramic as well as the onset of via "opens", particularly as via diameters are reduced below 100 um in high circuit density applications. A discussion of such problems is given in U.S. Patent 4,776,978, issued on Oct. 11, 1988 to Lester W. Herron et al. and assigned to the present assignee.
As set forth in the cited 4,776,978 patent, metal particles, such as copper, in the via paste undergo sintering with attendant shrinkage of the thick film pattern (also consisting of the paste) during the initial phase of the sintering cycle whereas the ceramic and glass particles (of the ceramic substrate containing the vias) undergo sintering during the intermediate and final phases of the sintering cycle along with their characteristic shrinkage. One method of delaying the onset of sintering of the metal particles until at least the intermediate phase of the sintering cycle is to intersperse the metal particles in the thick film with a high melting point material such as aluminum oxide.
Although the foregoing generalized considerations have been known in the art for some time and have provided the basis for techniques for overcoming previous 2 ~ ~ ~
Fl9--90--0~7 shrinkage and related proklems, more refined and detailed approaches are required to meet the needs of copper-filled vias in ceramic substrates with increasing circuit densities and the concomitant via diameters in the range of about 85 to 100 ~Im. It is also desirable to provide a copper paste mixture which can be adapted for use with the next generation of ceramic packages which exhibit reduced shrinkage from sintering.
The following references illustrate previous techniques attempting to overcome shrinkage and other problems.
U.S. Patent 4,594,181, issued on June 10~ 1986 to Vincent P. Siuta, teaches the dispersal of copper particles in a solution of an organometallic compound in an anhydrous volatile organic solvent towards obtaining a better shrinkage match of copper to ceramic substrate during sintering.
U.S. Patent *,599,277, issued on July 8, 1986 to James M. Brownlow et al., discloses the addition of an organometallic compound to a metal member such as copper paste which compound undergoes decomposition during sintering to provide a coating such as aluminum oxide on the copper particles towards obtaining better shrinkage match between copper and ceramic substrate during sintering.
Published European Patent Application, Publication No. 0272129, published June 22, 1988 by Hitoshi Suzuki et al., describes a paste composition including a copper powder and an organometallic compound such as an organoaluminate compound, towards obtaining improved adhesion strength of sintered copper to a ceramic substrate.
U.S. Patent 4,906,405, issued on March 6, 1990 to Seiichi Nakatani et al. and Japanese Patent J63095182, issued on April 26, 1988 to Goei Seisakusho KK, teach a paste made of copper oxide, and CuA1204 as an additive towards obtaining improved adhesion strength of sintered copper to a ceramic substrate.
~I9--90--027 3 ~ 7 Summary of the _Invention One object of the present invention is to provide a copper paste with appropriate additive to produce copper grain size in the range of about 5 to 15 ~m after sintering.
Another objec-t is to provlde a copper paste with an appropriate additive to substantially match the shrinkage of the resulting copper material to the shrinkage, if any, during sintering of a ceramic substrate having vias filled with said copper paste.
A further object is to provide a copper paste with an appropriate additive to provide substantially reduced shrinkage after sintering of the copper material in low shrinkage porous ceramic substrates having vias filled with said copper paste.
These and other objects of the present invention, as will be seen from a reading of the following specification, are achieved in a preferred embodiment of the present inv~ntion by the provision of a copper paste comprising copper powder, up to about 10 weight percent copper aluminate powder, and the remainder organic material. Use of copper aluminate in one preferred range from about 0.4 to about ]. weight percent provides the dual benefits of grain size control as well as shrinkage matchi.ng control of -the via copper during sintering.
It is preferred that the size of the copper aluminate particles be in the range of about 3.0 ~m or less because the amount of copper aluminate required for grain size control of the sintered Cu varies inversely with copper aluminate particle size.
In a preferred embodiment of the invention, glass-ceramic particles are added to the copper-based paste to provi~e a shrinkage match during sintering that is substantially identical to that of a glass-ceramic substrate.
Detailed Description of the_In ention Multilayered glass-ceramic packages for supporting and interconnecting microelectronic chip devices can be sintered to a peak temperature yreater than 950C.
Because of the high temperatures, the chip 2~i'3 7~ ~
i~terconnectin~ copper conductors tend to experience exaggerated grain ~rowth in the vias and in the thick film copp~r wirin~ lines.
The growth of large grains in copper is not desirable from the point of view of reliability. The reason for thi.s is that the plasticity of copper varies with the orientation of two neighboring large copper grains and the grains may separate when they are cooled down ~rom high temperature and on subsequent thermal cycling. Inasmuch as the conductor size in both the vias and surface lines is about 70-100 ~m, it is desirable to keep the copper grain size after sintering as small as possible, namely about 5-15 ~m.
In accordance with a first aspect of the present invention, copper grain size is minimized in a sintering cycles such as the one disclosed in the aforementioned 4,234,367 patent. Copper grain size is minimized by adding a small amount of copper aluminate powder to copper powder, mixing with suitable organics to form a paste, and then screening the paste using a mask on to a green sheet. The green sheet may comprise a variety of materials including, but not limited to, mullite, borosilicate glass, cordierite glass, ceramic, etc. The cordierite glass ceramic materials, such as that disclosed in Kumar et al. U.S. Patent 4,301,324, the disclosure of which is incorporated by reference herein, are preferred. Preferably, the copper powder has an average particle size of about 5-~ ~m and the copper aluminate powder has an average particle size of about 3.0 ~m or less.
There are two forms of copper aluminate, namely cupric aluminate (CuA1204) and cuprous aluminate ~CuA102). Unless specifically stated otherwise, whenever copper aluminate is mentioned in this specification, it should be understood that copper aluminate is being used in the generic sense to include cupric aluminate and cuprous aluminate, both of which should be considered to be within the scope of the present invention.
When suitable conditions are present in a sintering cycle such as taught in the 4,234,367 patent, copper Fl9--gO--027 5 2 ~ 7 aluminate decomposes iIltO copper and alumina according to the following reactions:
2~ H~ = Cu + A1203 + H 0 2 CuA102 + H2 = ~Cu + A1203 + H20 The alumina particles produced by the foregoing decomposition reactions are very small, submicron in size, and are distributed inside the copper matrix. The presence of a small amount of porosity and the small alumina particles insi.de the copper matrix have been found to inhibit copper grain growth and result in small copper grains after sintering at high temperature in excess of 950C.
More particularly, the unique use of powdered copper aluminate in the copper paste, in accordance with the present invention, has the special property of yielding grain size control of the sintered copper.
By adding powdered copper aluminate to copper paste, preferably in the range 0.2-]..0% by weight, the sintered copper grain size can be kept small. More importantly, the maximum grain size can be kept under about 20 ~m, which improves the reliability of multilayer ceramic packages having copper conductors. It should be noted that by decreasing the particle size of the copper aluminate powder~ smaller copper grain sizes can be obtained with lower weight percentage additions of the copper aluminate to the copper paste.
In general terms, grain size control is the predominant effect when the powdered copper aluminate paste additive is present up to about 1 weight percent.
Grain size control aids in avoiding opens (breaks~ in the sintered copper vias and circuits which have been experienced using other paste additives Which produce much larger copper qrain sizes after sintering.
It has been found that additions to the sintering paste of copper aluminate up to about 10 weight percent are useful for controlling the shrinkage of the sintered copper. With increasing amounts of copper aluminate, but not greater than about 10 weight percent, the sintered ~ ~ ~ 7 ~ 9~ ~ I
FI9 90--0~7 6 copper becomes porouF., i.e., the copper particles continue to shrink microscopically but not on a macro (global) scale~ At about 10 weight percent copper aluminate, the copper no longer undergoes shrinkage upon sinteri~g. It is more preferred that the copper aluminate be kept at about 3 weight percent or less since at higher amounts of copper aluminate, the sintered copper has lower strength and increased electrical resistivity.
It has further been found that shrinkage control is possible when there is present, as a minimum, a small but effective amount of copper aluminate. The lower limits have not been determined yet with precision. It is known that about .01 weight percent of alumina will induce shrinkag~ control. It is assumed, therefore, that amounts of copper aluminate (about 0.2 weight percent) that will yield about .01 weight percent alumina will also achieve similar shrinkage control, given similar particle sizes. Smaller amounts of copper aluminate are likely to be effective if the particle size of the copper aluminate, now at about 3.0 ~m, is reduced further.
As is apparent, the effects of grain size control and shrinkage control may advantageously overlap at small amounts of copper aluminate additions.
It would be most desirable to match or substantially match shrinkage characteristics during sintering of the copper vias and lines with that of a glass~ceramic, particularly a cordierite glass-ceramic, material. Thus, in a preferred embodiment of the invention, there is proposed a copper-based sintering paste comprising copper particles, glass-ceramic particles~ copper aluminate, and suitable organic binder materials. Based on volume percent of the inorganic solids, the paste comprises about 90 volume percent copper particles, about 5 to 12 volume percent glass-ceramic particles and about 0.3-1.5 volume percent copper aluminate.
It is preferred that the copper particles havP a bimodal distribution. Although a unimodal distribution of the copper particles (preferably having an average particle size of 5-8 ~m) will also work well. More FI9--90~ 7 7 preferably, there should be abou-t 60-90 volume percent copper particles having an average particle size of 5 to 6 ~m and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 ~m. Also preferably, the copper aluminate particles should have an average particle size of 0.7 to 3.0 ~m.
It is anticipated that the present invention will have applicability to many glass-ceramic materials. The preferred glass-ceramic materials, however, are the cordierite glass-ceramics disclosed in the Kumar et al.
U.S. Patent 4,301,324. The average particle size of the glass-ceramic particles should be about 3.5 ~m.
The advantages of the present invention will become more apparent after referring to the following examples.
EXAMPLES
Examples I
A series of samples were prepared comprising copper particles and varying amounts of copper aluminate in order to determine the efficacy of copper aluminate as a grain size control agent.
Batches of copper powder particles (from Metz Metallurgical and Dupont), having an average particle size of 6 ~m, were mixed with copper aluminate (CuA12 4)' having an average particle size of about 2.5 ~m, and various paste additives, including ethyl cellulose resin plus a solvent, wetting agent, and flow control agent.
Each batch was dried in an oven at about 100C and then milled in a rod mill for 1-2 hours. Thereafter, the paste was pressed into pellets at about 5000 psi.
Finally, the pellets were sintered in a sintering cycle such as that disclosed in the above Herron et al. U.S.
Patent 4,234~367.
The pellets were examined for grain size and the results are illustrated in Table I. As can be seen, the grain size is markedly reduced when at least 0.2 weight percent copper aluminate is present in the paste.
FI9 90--027 8 2~ J 2 7 TABLE I
Weight % Copper Average Grain Maximum Grain Aluminate InSize in CopperSize In Copper __ Paste ~m~ m~
0 >20 ~lO0 0.2 13 55 0.4 13 41 0.6 8 15 0.~ 8 19 1.0 7 14 The pellets were also examined for densification, noted as percent of theoretical density, and resistivity.
The results are illustrated in Table II. The samples listed in Table II only used the Metz copper powder particles. As can be seen, there is a steady decline in percent theoretical density achieved with increasing amounts of copper aluminate, thus illustrating the ability to control the shrinkage of the sintered copper.
TABLE_II
Weight % Copper % of Theoretical Resistivity Aluminate in Paste __ Density~-ohm-cm 0.3 93 0.4 91 2.2 1.0 ~0 2.9 1.2 76 3.1 2.0 73 3.0 69 10.0 55 Examples II
Samples were prepared comprising copper particles, copper aluminate particles and glass-ceramic particles in order to determine whether it is possible to match the F l g -- 9 0 - 0 2 7 ~ 7 7 2 ~
shrinkage characteristics during sintering of a copper paste and a glass-ceramic ma-terial.
A batch of copper-based paste was prepared having the following composition, by volume percent of inorganic materials: 10.08 volume percent of copper (from Metz Metallurgical) having an average particle size of 1.5 ~m, 79.26 volume percent of copper (from Metz Metallurgical) having an average particle size of 6 ~m, 9.9 volume percent of cordierite glass-ceramic particles (average particle size of 3.5 ~rn) of the composition listed in Table III, and 0.76 volume percent of copper aluminate having an average particle size of 0.6 ~m. To this mixture was added various past additions, including ethyl cellulose resin plus a solvent, wetting agent, and flow control agent. The resulting mixture was dried in an oven at about 100 C and then milled in a rod mill for 1 to 2 hours. Thereafter, the paste was pressed into pellets at about 5000 psi.
TABLE III
Glass-ceramic in Substrate Glass-paste, weight ~ Ceramic, weiqht ~
55.0 SiO2 55.0 21.23 A123 21.1 20.0 MgO 22.3 1.0 B203 1.3 2.77 P205 0 3 Next, a batch of glass-ceramic material (average particle size 3.5 ~m) representative of glass-ceramic material in substrates was prepared. The composition is also listed in Table III. The glass-ceramic material was prepared in a conventional way such as that disclosed in the Herron et al. U.S. Patent 4,234,367, and then pressed into pellets.
Generally speaking, the sintering cycle proceeds as follows. The temperature was ramped up to 715 C in an atmosphere of 70% water vapor/30% N2 followed by binder burnoff in a steam ambient. Subsequently, the atmosphere r ~ t J 7 Fi9-9~-027 1() was replaced wi~h a forming gas atmosphere and then the temperature was ramped up to ~75C in N2. The atmosphere is then changed to a steam ambient and heating at 975 C
continued to complete the second step. The pellets were then cooled down, firs-t in the steam ambient and then in N~.
The shrinkage behavior of -the pel]ets was measured during the sintering cycle by a Netzsch dilatometer. It was observed that the glass-ceramic pellets (representing the substrate) began to shrink at about 800C and stopped shrinking at about 860C, while the paste pellets began to shrink at about 800C and stopped shrinking at about 890C. Thus, both sets of pellets exhibited nearly identical shrinkage behavior. According to the invention, therefore, shrinkage matching of paste and substrate materials is obtained.
As is now apparent, the copper-based sintering paste comprising copper aluminate proposed by the present inventors has fulfilled the dual objectives of controlling the grain size in the sintered copper while also altering the shrinkage behavior of the copper particles.
It will be apparent to those skilled in the art having regard to this disclosure that other modifications of this invention beyond those embodiments specifically described here may be made without departing from the spirit of the invention. Accordingly, such modifications are considered within the scope of the invention as limited solely by the appended claims.
COPPER-BASED PASTE CONTAINING COPPER ALUMI_ATE
E'OR_MICROSTRUCTURAL AND_SHRINKAGE CO T OL
OF COPPER-FILLED_~iIAS
Ba~ground of the_Inventlon The present invention generally relates to copper-filled vias in ceramic substrates and, more particularly, to a copper-based paste containing copper aluminate powder in proper particle size and weight proportion for grain size and shrinkage control of the via and thick film copper produced by sintering.
The use of copper-filled vias in ceramic substrates and sintering processes for producing them are well known in the semiconductor packaging art as taught, for example, in U.S. Patent 4,234,367, issued on Nov. 18, 1980 to Lester W. Herron et al. and assigned to the present assignee. Recently, more interest has been focused on the associated problems of the disparity in shrinkage rates between copper and ceramic as well as the onset of via "opens", particularly as via diameters are reduced below 100 um in high circuit density applications. A discussion of such problems is given in U.S. Patent 4,776,978, issued on Oct. 11, 1988 to Lester W. Herron et al. and assigned to the present assignee.
As set forth in the cited 4,776,978 patent, metal particles, such as copper, in the via paste undergo sintering with attendant shrinkage of the thick film pattern (also consisting of the paste) during the initial phase of the sintering cycle whereas the ceramic and glass particles (of the ceramic substrate containing the vias) undergo sintering during the intermediate and final phases of the sintering cycle along with their characteristic shrinkage. One method of delaying the onset of sintering of the metal particles until at least the intermediate phase of the sintering cycle is to intersperse the metal particles in the thick film with a high melting point material such as aluminum oxide.
Although the foregoing generalized considerations have been known in the art for some time and have provided the basis for techniques for overcoming previous 2 ~ ~ ~
Fl9--90--0~7 shrinkage and related proklems, more refined and detailed approaches are required to meet the needs of copper-filled vias in ceramic substrates with increasing circuit densities and the concomitant via diameters in the range of about 85 to 100 ~Im. It is also desirable to provide a copper paste mixture which can be adapted for use with the next generation of ceramic packages which exhibit reduced shrinkage from sintering.
The following references illustrate previous techniques attempting to overcome shrinkage and other problems.
U.S. Patent 4,594,181, issued on June 10~ 1986 to Vincent P. Siuta, teaches the dispersal of copper particles in a solution of an organometallic compound in an anhydrous volatile organic solvent towards obtaining a better shrinkage match of copper to ceramic substrate during sintering.
U.S. Patent *,599,277, issued on July 8, 1986 to James M. Brownlow et al., discloses the addition of an organometallic compound to a metal member such as copper paste which compound undergoes decomposition during sintering to provide a coating such as aluminum oxide on the copper particles towards obtaining better shrinkage match between copper and ceramic substrate during sintering.
Published European Patent Application, Publication No. 0272129, published June 22, 1988 by Hitoshi Suzuki et al., describes a paste composition including a copper powder and an organometallic compound such as an organoaluminate compound, towards obtaining improved adhesion strength of sintered copper to a ceramic substrate.
U.S. Patent 4,906,405, issued on March 6, 1990 to Seiichi Nakatani et al. and Japanese Patent J63095182, issued on April 26, 1988 to Goei Seisakusho KK, teach a paste made of copper oxide, and CuA1204 as an additive towards obtaining improved adhesion strength of sintered copper to a ceramic substrate.
~I9--90--027 3 ~ 7 Summary of the _Invention One object of the present invention is to provide a copper paste with appropriate additive to produce copper grain size in the range of about 5 to 15 ~m after sintering.
Another objec-t is to provlde a copper paste with an appropriate additive to substantially match the shrinkage of the resulting copper material to the shrinkage, if any, during sintering of a ceramic substrate having vias filled with said copper paste.
A further object is to provide a copper paste with an appropriate additive to provide substantially reduced shrinkage after sintering of the copper material in low shrinkage porous ceramic substrates having vias filled with said copper paste.
These and other objects of the present invention, as will be seen from a reading of the following specification, are achieved in a preferred embodiment of the present inv~ntion by the provision of a copper paste comprising copper powder, up to about 10 weight percent copper aluminate powder, and the remainder organic material. Use of copper aluminate in one preferred range from about 0.4 to about ]. weight percent provides the dual benefits of grain size control as well as shrinkage matchi.ng control of -the via copper during sintering.
It is preferred that the size of the copper aluminate particles be in the range of about 3.0 ~m or less because the amount of copper aluminate required for grain size control of the sintered Cu varies inversely with copper aluminate particle size.
In a preferred embodiment of the invention, glass-ceramic particles are added to the copper-based paste to provi~e a shrinkage match during sintering that is substantially identical to that of a glass-ceramic substrate.
Detailed Description of the_In ention Multilayered glass-ceramic packages for supporting and interconnecting microelectronic chip devices can be sintered to a peak temperature yreater than 950C.
Because of the high temperatures, the chip 2~i'3 7~ ~
i~terconnectin~ copper conductors tend to experience exaggerated grain ~rowth in the vias and in the thick film copp~r wirin~ lines.
The growth of large grains in copper is not desirable from the point of view of reliability. The reason for thi.s is that the plasticity of copper varies with the orientation of two neighboring large copper grains and the grains may separate when they are cooled down ~rom high temperature and on subsequent thermal cycling. Inasmuch as the conductor size in both the vias and surface lines is about 70-100 ~m, it is desirable to keep the copper grain size after sintering as small as possible, namely about 5-15 ~m.
In accordance with a first aspect of the present invention, copper grain size is minimized in a sintering cycles such as the one disclosed in the aforementioned 4,234,367 patent. Copper grain size is minimized by adding a small amount of copper aluminate powder to copper powder, mixing with suitable organics to form a paste, and then screening the paste using a mask on to a green sheet. The green sheet may comprise a variety of materials including, but not limited to, mullite, borosilicate glass, cordierite glass, ceramic, etc. The cordierite glass ceramic materials, such as that disclosed in Kumar et al. U.S. Patent 4,301,324, the disclosure of which is incorporated by reference herein, are preferred. Preferably, the copper powder has an average particle size of about 5-~ ~m and the copper aluminate powder has an average particle size of about 3.0 ~m or less.
There are two forms of copper aluminate, namely cupric aluminate (CuA1204) and cuprous aluminate ~CuA102). Unless specifically stated otherwise, whenever copper aluminate is mentioned in this specification, it should be understood that copper aluminate is being used in the generic sense to include cupric aluminate and cuprous aluminate, both of which should be considered to be within the scope of the present invention.
When suitable conditions are present in a sintering cycle such as taught in the 4,234,367 patent, copper Fl9--gO--027 5 2 ~ 7 aluminate decomposes iIltO copper and alumina according to the following reactions:
2~ H~ = Cu + A1203 + H 0 2 CuA102 + H2 = ~Cu + A1203 + H20 The alumina particles produced by the foregoing decomposition reactions are very small, submicron in size, and are distributed inside the copper matrix. The presence of a small amount of porosity and the small alumina particles insi.de the copper matrix have been found to inhibit copper grain growth and result in small copper grains after sintering at high temperature in excess of 950C.
More particularly, the unique use of powdered copper aluminate in the copper paste, in accordance with the present invention, has the special property of yielding grain size control of the sintered copper.
By adding powdered copper aluminate to copper paste, preferably in the range 0.2-]..0% by weight, the sintered copper grain size can be kept small. More importantly, the maximum grain size can be kept under about 20 ~m, which improves the reliability of multilayer ceramic packages having copper conductors. It should be noted that by decreasing the particle size of the copper aluminate powder~ smaller copper grain sizes can be obtained with lower weight percentage additions of the copper aluminate to the copper paste.
In general terms, grain size control is the predominant effect when the powdered copper aluminate paste additive is present up to about 1 weight percent.
Grain size control aids in avoiding opens (breaks~ in the sintered copper vias and circuits which have been experienced using other paste additives Which produce much larger copper qrain sizes after sintering.
It has been found that additions to the sintering paste of copper aluminate up to about 10 weight percent are useful for controlling the shrinkage of the sintered copper. With increasing amounts of copper aluminate, but not greater than about 10 weight percent, the sintered ~ ~ ~ 7 ~ 9~ ~ I
FI9 90--0~7 6 copper becomes porouF., i.e., the copper particles continue to shrink microscopically but not on a macro (global) scale~ At about 10 weight percent copper aluminate, the copper no longer undergoes shrinkage upon sinteri~g. It is more preferred that the copper aluminate be kept at about 3 weight percent or less since at higher amounts of copper aluminate, the sintered copper has lower strength and increased electrical resistivity.
It has further been found that shrinkage control is possible when there is present, as a minimum, a small but effective amount of copper aluminate. The lower limits have not been determined yet with precision. It is known that about .01 weight percent of alumina will induce shrinkag~ control. It is assumed, therefore, that amounts of copper aluminate (about 0.2 weight percent) that will yield about .01 weight percent alumina will also achieve similar shrinkage control, given similar particle sizes. Smaller amounts of copper aluminate are likely to be effective if the particle size of the copper aluminate, now at about 3.0 ~m, is reduced further.
As is apparent, the effects of grain size control and shrinkage control may advantageously overlap at small amounts of copper aluminate additions.
It would be most desirable to match or substantially match shrinkage characteristics during sintering of the copper vias and lines with that of a glass~ceramic, particularly a cordierite glass-ceramic, material. Thus, in a preferred embodiment of the invention, there is proposed a copper-based sintering paste comprising copper particles, glass-ceramic particles~ copper aluminate, and suitable organic binder materials. Based on volume percent of the inorganic solids, the paste comprises about 90 volume percent copper particles, about 5 to 12 volume percent glass-ceramic particles and about 0.3-1.5 volume percent copper aluminate.
It is preferred that the copper particles havP a bimodal distribution. Although a unimodal distribution of the copper particles (preferably having an average particle size of 5-8 ~m) will also work well. More FI9--90~ 7 7 preferably, there should be abou-t 60-90 volume percent copper particles having an average particle size of 5 to 6 ~m and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 ~m. Also preferably, the copper aluminate particles should have an average particle size of 0.7 to 3.0 ~m.
It is anticipated that the present invention will have applicability to many glass-ceramic materials. The preferred glass-ceramic materials, however, are the cordierite glass-ceramics disclosed in the Kumar et al.
U.S. Patent 4,301,324. The average particle size of the glass-ceramic particles should be about 3.5 ~m.
The advantages of the present invention will become more apparent after referring to the following examples.
EXAMPLES
Examples I
A series of samples were prepared comprising copper particles and varying amounts of copper aluminate in order to determine the efficacy of copper aluminate as a grain size control agent.
Batches of copper powder particles (from Metz Metallurgical and Dupont), having an average particle size of 6 ~m, were mixed with copper aluminate (CuA12 4)' having an average particle size of about 2.5 ~m, and various paste additives, including ethyl cellulose resin plus a solvent, wetting agent, and flow control agent.
Each batch was dried in an oven at about 100C and then milled in a rod mill for 1-2 hours. Thereafter, the paste was pressed into pellets at about 5000 psi.
Finally, the pellets were sintered in a sintering cycle such as that disclosed in the above Herron et al. U.S.
Patent 4,234~367.
The pellets were examined for grain size and the results are illustrated in Table I. As can be seen, the grain size is markedly reduced when at least 0.2 weight percent copper aluminate is present in the paste.
FI9 90--027 8 2~ J 2 7 TABLE I
Weight % Copper Average Grain Maximum Grain Aluminate InSize in CopperSize In Copper __ Paste ~m~ m~
0 >20 ~lO0 0.2 13 55 0.4 13 41 0.6 8 15 0.~ 8 19 1.0 7 14 The pellets were also examined for densification, noted as percent of theoretical density, and resistivity.
The results are illustrated in Table II. The samples listed in Table II only used the Metz copper powder particles. As can be seen, there is a steady decline in percent theoretical density achieved with increasing amounts of copper aluminate, thus illustrating the ability to control the shrinkage of the sintered copper.
TABLE_II
Weight % Copper % of Theoretical Resistivity Aluminate in Paste __ Density~-ohm-cm 0.3 93 0.4 91 2.2 1.0 ~0 2.9 1.2 76 3.1 2.0 73 3.0 69 10.0 55 Examples II
Samples were prepared comprising copper particles, copper aluminate particles and glass-ceramic particles in order to determine whether it is possible to match the F l g -- 9 0 - 0 2 7 ~ 7 7 2 ~
shrinkage characteristics during sintering of a copper paste and a glass-ceramic ma-terial.
A batch of copper-based paste was prepared having the following composition, by volume percent of inorganic materials: 10.08 volume percent of copper (from Metz Metallurgical) having an average particle size of 1.5 ~m, 79.26 volume percent of copper (from Metz Metallurgical) having an average particle size of 6 ~m, 9.9 volume percent of cordierite glass-ceramic particles (average particle size of 3.5 ~rn) of the composition listed in Table III, and 0.76 volume percent of copper aluminate having an average particle size of 0.6 ~m. To this mixture was added various past additions, including ethyl cellulose resin plus a solvent, wetting agent, and flow control agent. The resulting mixture was dried in an oven at about 100 C and then milled in a rod mill for 1 to 2 hours. Thereafter, the paste was pressed into pellets at about 5000 psi.
TABLE III
Glass-ceramic in Substrate Glass-paste, weight ~ Ceramic, weiqht ~
55.0 SiO2 55.0 21.23 A123 21.1 20.0 MgO 22.3 1.0 B203 1.3 2.77 P205 0 3 Next, a batch of glass-ceramic material (average particle size 3.5 ~m) representative of glass-ceramic material in substrates was prepared. The composition is also listed in Table III. The glass-ceramic material was prepared in a conventional way such as that disclosed in the Herron et al. U.S. Patent 4,234,367, and then pressed into pellets.
Generally speaking, the sintering cycle proceeds as follows. The temperature was ramped up to 715 C in an atmosphere of 70% water vapor/30% N2 followed by binder burnoff in a steam ambient. Subsequently, the atmosphere r ~ t J 7 Fi9-9~-027 1() was replaced wi~h a forming gas atmosphere and then the temperature was ramped up to ~75C in N2. The atmosphere is then changed to a steam ambient and heating at 975 C
continued to complete the second step. The pellets were then cooled down, firs-t in the steam ambient and then in N~.
The shrinkage behavior of -the pel]ets was measured during the sintering cycle by a Netzsch dilatometer. It was observed that the glass-ceramic pellets (representing the substrate) began to shrink at about 800C and stopped shrinking at about 860C, while the paste pellets began to shrink at about 800C and stopped shrinking at about 890C. Thus, both sets of pellets exhibited nearly identical shrinkage behavior. According to the invention, therefore, shrinkage matching of paste and substrate materials is obtained.
As is now apparent, the copper-based sintering paste comprising copper aluminate proposed by the present inventors has fulfilled the dual objectives of controlling the grain size in the sintered copper while also altering the shrinkage behavior of the copper particles.
It will be apparent to those skilled in the art having regard to this disclosure that other modifications of this invention beyond those embodiments specifically described here may be made without departing from the spirit of the invention. Accordingly, such modifications are considered within the scope of the invention as limited solely by the appended claims.
Claims (30)
1. A copper-based sintering paste for forming conductive vias and surface patterns in or on ceramic substrates, said paste comprising:
powdered copper particles, powdered copper aluminate particles and organic materials, said copper aluminate constituting up to 10%
by weight of said paste.
powdered copper particles, powdered copper aluminate particles and organic materials, said copper aluminate constituting up to 10%
by weight of said paste.
2. The sintering paste defined in claim 1 wherein said copper aluminate constitutes up to 3% by weight of said paste.
3. The sintering paste defined in claim 1 wherein said copper aluminate is present as a minimum in a small but effective amount to control shrinkage of said paste.
4. The sintering paste defined in claim 1 wherein said copper aluminate constitutes .02-10% by weight of said paste.
5. The sintering paste defined in claim 4 wherein said copper aluminate constitutes .02-3% by weight of said paste.
6. The sintering paste defined in claim 5 wherein said copper aluminate constitutes .02-1% by weight of said paste.
7. The sintering paste defined in claim 6 wherein said copper aluminate constitutes 0.2-1% by weight of said paste.
8. The sintering paste defined in claim 7 wherein the average size of said copper aluminate particles is not greater than about 3.0 micrometers.
9. The sintering paste defined in claim 7 wherein the average size of said copper particles is about 5-8 micrometers.
10. The sintering paste defined in claim 1 wherein said copper aluminate constitutes 0.2-1% by weight of said paste, the average size of said copper aluminate particles is not greater than about 3.0 micrometers, and the average size of said copper particles is about 5-8 micrometers.
11. A multilayered ceramic package comprising:
a ceramic substrate; and a copper-based sintering paste for forming conductive vias and surface patterns in or on said ceramic substrate, said paste comprising:
powdered copper particles, powdered copper aluminate particles and organic materials, said copper aluminate constituting up to 10%
by weight of said paste.
a ceramic substrate; and a copper-based sintering paste for forming conductive vias and surface patterns in or on said ceramic substrate, said paste comprising:
powdered copper particles, powdered copper aluminate particles and organic materials, said copper aluminate constituting up to 10%
by weight of said paste.
12. The ceramic package defined in claim 11 wherein said copper aluminate in said sintering paste constitutes up to 3% by weight of said paste.
13. The ceramic package defined in claim 11 wherein said copper aluminate in said sintering paste is present as a minimum in a small but effective amount to control shrinkage of said paste.
14. The ceramic package defined in claim 11 wherein said copper aluminate in said sintering paste constitutes .02-10% by weight of said paste.
15. The ceramic package defined in claim 14 wherein said copper aluminate constitutes .02-3% by weight of said paste.
16. The ceramic package defined in claim 15 wherein said copper aluminate constitutes .02-1% by weight of said paste.
17. The ceramic package defined in claim 16 wherein said copper aluminate constitutes 0.2-1% by weight of said paste.
18. The ceramic package defined in claim 17 wherein the average size of said copper aluminate particles is not greater than 3.0 micrometers.
19. The ceramic package defined in claim 17 wherein the average size of said copper particles is about 5-8 micrometers.
20. The ceramic package defined in claim 1 wherein in said sintering paste said copper aluminate constitutes 0.2 1% weight of said paste, the average size of said copper aluminate particles is not greater than about 3.0 micrometers, and the average size of said copper particles is about 5-8 micrometers.
21. A copper-based sintering paste for forming conductive vias and surface patterns in or on glass-ceramic substrates, said paste comprising, by volume percent of inorganic solids:
90 volume percent copper particles, 5-12 volume percent glass-ceramic particles, 0.3-1.5 volume percent copper aluminate particles, and organic materials.
90 volume percent copper particles, 5-12 volume percent glass-ceramic particles, 0.3-1.5 volume percent copper aluminate particles, and organic materials.
22. The sintering paste defined in claim 21 wherein said copper particles have a bimodal distribution.
23. The sintering paste defined in claim 22 wherein said copper particle bimodal distribution comprises, by volume percent of inorganic solids:
60-90 volume percent of copper particles having an average particle size of 5 to 6 micrometers and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 micrometers.
60-90 volume percent of copper particles having an average particle size of 5 to 6 micrometers and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 micrometers.
24. The sintering paste defined in claim 21 wherein said glass-ceramic particles have an average particle size of 3.5 micrometers and said copper aluminate particles have an average particle size of 0.7 to 3.0 micrometers.
25. The sintering paste defined in claim 21 wherein said paste substantially matches the shrinkage characteristics of said glass-ceramic substrate during sintering.
26. A multilayered ceramic package comprising:
a glass-ceramic substrate; and a copper-based sintering paste for forming conductive vias and surface patterns in or on said glass-ceramic substrate, said paste comprising:
by volume percent of inorganic solids:
90 volume percent of copper particles, 5-12 volume percent of glass-ceramic particles, 0.3-1.5 volume percent of copper aluminate particles, and organic materials.
a glass-ceramic substrate; and a copper-based sintering paste for forming conductive vias and surface patterns in or on said glass-ceramic substrate, said paste comprising:
by volume percent of inorganic solids:
90 volume percent of copper particles, 5-12 volume percent of glass-ceramic particles, 0.3-1.5 volume percent of copper aluminate particles, and organic materials.
27. The ceramic package defined in claim 26 wherein said copper particles in said sintering paste have a bimodal distribution.
28. The ceramic package defined in claim 27 wherein said copper particle bimodal distribution comprises, by volume percent of inorganic solids:
60-90 volume percent of copper particles having an average particle size of 5 to 6 micrometers and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 micrometers.
60-90 volume percent of copper particles having an average particle size of 5 to 6 micrometers and 0-30 volume percent of copper particles having an average particle size of 1.5 to 2.0 micrometers.
29. The ceramic package defined in claim 26 wherein in said sintering paste said glass-ceramic particles have an average particle size of 3.5 micrometers and said copper aluminate particles have an average particle size of 0.7-3.0 micrometers.
30. The ceramic package defined in claim 26 wherein said sintering paste substantially matches the shrinkage characteristics of said glass-ceramic substrate during sintering.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/758,991 US5925443A (en) | 1991-09-10 | 1991-09-10 | Copper-based paste containing copper aluminate for microstructural and shrinkage control of copper-filled vias |
| US07/758,991 | 1991-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2072727A1 true CA2072727A1 (en) | 1993-03-11 |
Family
ID=25053958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2072727 Abandoned CA2072727A1 (en) | 1991-09-10 | 1992-06-29 | Copper-based paste containing copper aluminate, for microstructural and shrinkage control of copper-filled vias |
Country Status (7)
| Country | Link |
|---|---|
| US (3) | US5925443A (en) |
| EP (1) | EP0606216B1 (en) |
| JP (1) | JPH0817217B2 (en) |
| BR (1) | BR9203415A (en) |
| CA (1) | CA2072727A1 (en) |
| DE (1) | DE69208675T2 (en) |
| WO (1) | WO1993005632A1 (en) |
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| DE69329357T2 (en) * | 1992-05-14 | 2001-04-26 | Matsushita Electric Ind Co Ltd | Process for the production of conductors in contact holes in multilayer ceramic substrates |
| US5698015A (en) * | 1995-05-19 | 1997-12-16 | Nikko Company | Conductor paste for plugging through-holes in ceramic circuit boards and a ceramic circuit board having this conductor paste |
| EP0883442A4 (en) * | 1995-06-06 | 1999-10-27 | Sarnoff Corp | Electrokinetic pumping |
| US20030148024A1 (en) * | 2001-10-05 | 2003-08-07 | Kodas Toivo T. | Low viscosity precursor compositons and methods for the depositon of conductive electronic features |
| US6376054B1 (en) * | 1999-02-10 | 2002-04-23 | International Business Machines Corporation | Surface metallization structure for multiple chip test and burn-in |
| US6171988B1 (en) * | 1999-07-30 | 2001-01-09 | International Business Machines Corporation | Low loss glass ceramic composition with modifiable dielectric constant |
| US7605328B2 (en) * | 2004-02-19 | 2009-10-20 | Nanosolar, Inc. | Photovoltaic thin-film cell produced from metallic blend using high-temperature printing |
| US7700464B2 (en) * | 2004-02-19 | 2010-04-20 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from nanoflake particles |
| US8846141B1 (en) | 2004-02-19 | 2014-09-30 | Aeris Capital Sustainable Ip Ltd. | High-throughput printing of semiconductor precursor layer from microflake particles |
| US20070163642A1 (en) * | 2004-02-19 | 2007-07-19 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from inter-metallic microflake articles |
| US8623448B2 (en) * | 2004-02-19 | 2014-01-07 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from chalcogenide microflake particles |
| US8372734B2 (en) | 2004-02-19 | 2013-02-12 | Nanosolar, Inc | High-throughput printing of semiconductor precursor layer from chalcogenide nanoflake particles |
| US7663057B2 (en) * | 2004-02-19 | 2010-02-16 | Nanosolar, Inc. | Solution-based fabrication of photovoltaic cell |
| US7604843B1 (en) * | 2005-03-16 | 2009-10-20 | Nanosolar, Inc. | Metallic dispersion |
| US8309163B2 (en) * | 2004-02-19 | 2012-11-13 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer by use of chalcogen-containing vapor and inter-metallic material |
| US20070163639A1 (en) * | 2004-02-19 | 2007-07-19 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from microflake particles |
| US8329501B1 (en) | 2004-02-19 | 2012-12-11 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from inter-metallic microflake particles |
| US20070169809A1 (en) * | 2004-02-19 | 2007-07-26 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer by use of low-melting chalcogenides |
| US20070163641A1 (en) * | 2004-02-19 | 2007-07-19 | Nanosolar, Inc. | High-throughput printing of semiconductor precursor layer from inter-metallic nanoflake particles |
| US8048477B2 (en) * | 2004-02-19 | 2011-11-01 | Nanosolar, Inc. | Chalcogenide solar cells |
| TWI422485B (en) * | 2010-12-31 | 2014-01-11 | Tong Hsing Electronic Ind Ltd | A ceramic plate with reflective film and method of manufacturing the same |
| WO2020171940A1 (en) | 2019-02-21 | 2020-08-27 | Corning Incorporated | Glass or glass ceramic articles with copper-metallized through holes and processes for making the same |
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| US3838071A (en) * | 1972-06-30 | 1974-09-24 | Du Pont | High adhesion silver-based metallizations |
| US4072771A (en) * | 1975-11-28 | 1978-02-07 | Bala Electronics Corporation | Copper thick film conductor |
| US4090009A (en) * | 1977-03-11 | 1978-05-16 | E. I. Du Pont De Nemours And Company | Novel silver compositions |
| US4301324A (en) * | 1978-02-06 | 1981-11-17 | International Business Machines Corporation | Glass-ceramic structures and sintered multilayer substrates thereof with circuit patterns of gold, silver or copper |
| US4234367A (en) * | 1979-03-23 | 1980-11-18 | International Business Machines Corporation | Method of making multilayered glass-ceramic structures having an internal distribution of copper-based conductors |
| FR2508054A1 (en) * | 1981-06-19 | 1982-12-24 | Labo Electronique Physique | DEPARTURE MIXTURE FOR A SERIGRAPIABLE INK CONTAINING NON-OXIDIZING ATMOSPHERE-CONTAINING LEAD GLASS AND SERIGRAPIABLE INK OBTAINED |
| US4584181A (en) * | 1982-12-27 | 1986-04-22 | Sri International | Process and apparatus for obtaining silicon from fluosilicic acid |
| US4503090A (en) * | 1983-02-23 | 1985-03-05 | At&T Bell Laboratories | Thick film resistor circuits |
| US4776978A (en) * | 1984-04-26 | 1988-10-11 | International Business Machines Corporation | Method of controlling the sintering of metal particles |
| JPS61183807A (en) * | 1985-02-08 | 1986-08-16 | 松下電器産業株式会社 | Metalized composition |
| US4594181A (en) * | 1984-09-17 | 1986-06-10 | E. I. Du Pont De Nemours And Company | Metal oxide-coated copper powder |
| US4599277A (en) * | 1984-10-09 | 1986-07-08 | International Business Machines Corp. | Control of the sintering of powdered metals |
| US5100714A (en) * | 1986-07-24 | 1992-03-31 | Ceramic Packaging, Inc. | Metallized ceramic substrate and method therefor |
| JPH0246553B2 (en) * | 1986-10-03 | 1990-10-16 | Goei Seisakusho Kk | METARAIZUKASHITA SERAMITSUKUSUOYOBISONOSEIZOHOHO |
| CA1273853C (en) * | 1986-12-17 | 1990-09-11 | Method for production of ceramic circuit board | |
| US4906405A (en) * | 1987-05-19 | 1990-03-06 | Matsushita Electric Industrial Co., Ltd. | Conductor composition and method of manufacturing a multilayered ceramic body using the composition |
| JPS63291304A (en) * | 1987-05-22 | 1988-11-29 | Matsushita Electric Ind Co Ltd | Metallized constituent |
| JPS63292504A (en) * | 1987-05-26 | 1988-11-29 | Matsushita Electric Works Ltd | Conductor paste |
| US4865722A (en) | 1987-09-01 | 1989-09-12 | Max Ririe | Method and apparatus for separation using fluidized bed |
| JPH01192781A (en) * | 1988-01-26 | 1989-08-02 | Dai Ichi Kogyo Seiyaku Co Ltd | Thick film copper conductor composition |
| JPH0728128B2 (en) * | 1988-03-11 | 1995-03-29 | 松下電器産業株式会社 | Ceramic multilayer wiring board and manufacturing method thereof |
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-
1991
- 1991-09-10 US US07/758,991 patent/US5925443A/en not_active Expired - Fee Related
-
1992
- 1992-06-23 DE DE1992608675 patent/DE69208675T2/en not_active Expired - Fee Related
- 1992-06-23 WO PCT/EP1992/001414 patent/WO1993005632A1/en active IP Right Grant
- 1992-06-23 EP EP19920913656 patent/EP0606216B1/en not_active Expired - Lifetime
- 1992-06-29 CA CA 2072727 patent/CA2072727A1/en not_active Abandoned
- 1992-08-03 JP JP20631392A patent/JPH0817217B2/en not_active Expired - Lifetime
- 1992-09-01 BR BR9203415A patent/BR9203415A/en active Search and Examination
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1995
- 1995-06-06 US US08/466,562 patent/US6358439B1/en not_active Expired - Fee Related
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1999
- 1999-03-11 US US09/266,338 patent/US6124041A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US5925443A (en) | 1999-07-20 |
| DE69208675T2 (en) | 1996-09-26 |
| DE69208675D1 (en) | 1996-04-04 |
| JPH0817217B2 (en) | 1996-02-21 |
| WO1993005632A1 (en) | 1993-03-18 |
| EP0606216A1 (en) | 1994-07-20 |
| JPH05198698A (en) | 1993-08-06 |
| US6358439B1 (en) | 2002-03-19 |
| EP0606216B1 (en) | 1996-02-28 |
| BR9203415A (en) | 1993-04-13 |
| US6124041A (en) | 2000-09-26 |
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