US4642148A
Expired / Lapsed
US
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Method for producing a multilayer ceramic circuit board
Assignee: Fujitsu Ltd
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Filing: 1985-05-28
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Granted: 1987-02-10
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Expires: 2005-05-28
Abstract
Abstract A method for producing a multilayer ceramic circuit board including the steps of forming a multilayer structure consisting of patterns of copper-based paste and glass-ceramic layers, the glass-ceramic layers consisting of a mixture of 10 percent to 75 percent by weight of alpha -alumina, 20 percent to 60 percent by weight of crystallizable or noncrystallizable glass which can be sintered at a temperature lower than the melting point of copper, and 5 percent to 70 percent by weight of quartz glass, based on the total weight of the glass-ceramic, blended with a binder containing a thermally depolymerizable resin; prefiring the multilayer structure in an inert atmosphere containing water vapor, the partial pressure of which is 0.005 to 0.3 atmosphere, at a temperature where the thermally depolymerizable resin is eliminated; and firing the multilayer structure in an inert atmosphere containing no water vapor at a temperature below the melting point of copper so as to sinter the glass-ceramic.
Inventors
- 👤 Kazuaki Kurihara
- 👤 Nobuo Kamehara
- 👤 Hiromitsu Yokoyama
- 👤 Hiromi Ogawa
- 👤 Kishio Yokouchi
- 👤 Yoshihiko Imanaka
- 👤 Koichi Niwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:30
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/46; H05K3/4644; H05K3/4664; H05K3/4667; C; C03; C03C; C03C10/00; C03C10/0009; H05K1/00; H05K1/02; H05K1/03; H05K1/0306; H05K3/4611; H05K3/4626; H05K3/4629; H10; H10W; H10W70/00; H10W70/01; H10W70/05; H10W70/098; H10W70/60; H10W70/67; H10W70/69; H10W70/692; C03C2214/00; C03C2214/04; C03C2214/20; H05K1/09; H05K1/092; H05K2203/00; H05K2203/08; H05K2203/086; H05K2203/088; H05K2203/11; H05K2203/1126; H05K3/10; H05K3/12; H05K3/1283; H05K3/1291; Y; Y10; Y10S; Y10S428/00; Y10S428/901; Y10T; Y10T428/00; Y10T428/24; Y10T428/24273; Y10T428/24322; Y10T428/24802; Y10T428/24917; Y10T428/24926; Y10T428/25; Y10T428/252
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
288 words
A method for producing a multilayer ceramic circuit board for use with copper conductors comprising the steps of: forming a multilayer structure comprising patterns of copper-based paste and glass-ceramic layers laminated alternately, at least the glass-ceramic layers located between the patterns of copper-based paste consisting essentially of a mixture of 10 percent to 75 percent by weight of α-alumina, 20 percent to 60 percent by weight of crystallizable or noncrystallizable glass which is sinterable at a temperature lower than the melting point of copper and not coalescent at temperatures up to 900° C., and 5 percent to 70 percent by weight of quartz glass, based on the total weight of the glass-ceramic, blended with a binder comprising a thermally depolymerizable resin; prefiring the multilayer structure in an inert atmosphere containing water vapor, the partial pressure of which is 0.005 to 0.3 atmosphere, in a first prefiring step at a temperature in the range of 350° C. to 450° C. and for a time sufficient to depolymerize substantially all of the resin and in second prefiring step at a temperature in the range of 650° C. to 900° C. and for a time sufficient to assure completion of depolymerization of the resin and to reduce any residual carbon to a desired minimal level, while producing no substantial change in the state of the glass components and the copper; and firing the multilayer structure in an inert atmosphere containing no water vapor at a temperature in the range of from above 900° C. to below the melting point of copper so as to coalesce the crystallizable or noncrystallizable glass and thereby sinter the glass-ceramic without affecting the metallic state of the copper or coalescing the α-alumina and quartz glass components.
Claim 2
Independent Claim
288 words
A method for producing a multilayer ceramic circuit board for use with copper conductors comprising the steps of: forming a multilayer structure comprising patterns of copper-based paste and glass-ceramic layers laminated alternately, at least the glass-ceramic layers located between the patterns of copper-based paste consisting essentially of a mixture of 10 percent to 75 percent by weight of α-alumina, 20 percent to 60 percent by weight of crystallizable or noncrystallizable glass which is sinterable at a temperature lower than the melting point of copper and not coalescent at temperatures up to 900° C., and 5 percent to 70 percent by weight of quartz glass, based on the total weight of the glass-ceramic, blended with a binder comprising a thermally depolymerizable resin; prefiring the multilayer structure in an inert atmosphere containing water vapor, the partial pressure of which is 0.005 to 0.3 atmosphere, in a first prefiring step at a temperature in the range of 350° C. to 450° C. and for a time sufficient to depolymerize substantially all of the resin and in second prefiring step at a temperature in the range of 650° C. to 900° C. and for a time sufficient to assure completion of depolymerization of the resin and to reduce any residual carbon to a desired minimal level, while producing no substantial change in the state of the glass components and the copper; and firing the multilayer structure in an inert atmosphere containing no water vapor at a temperature in the range of from above 900° C. to below the melting point of copper so as to coalesce the crystallizable or noncrystallizable glass and thereby sinter the glass-ceramic without affecting the metallic state of the copper or coalescing the α-alumina and quartz glass components.
Claim 3
Dependent Claim
14 words
A method according to claim 1, wherein said crystallizable glass comprises cordierite or spoduemene.
Claim 4
Dependent Claim
16 words
A method according to claim 1, wherein said noncrystallizable glass comprises borosilicate glass or aluminosilicate glass.
Claim 5
Dependent Claim
20 words
A method according to claim 1, wherein said thermally depolymerizable resin comprises polymethacrylate ester, polytetrafluoroethylene, poly-α-methylstyrene, or a mixture thereof.
Claim 6
Dependent Claim
19 words
A method according to claim 1, wherein: said firing is carried out at a temperature lower than 1083° C.
Claim 7
Dependent Claim
20 words
A method according to claim 1, wherein said multilayer structure is formed by means of a laminated green sheet technique.
Claim 8
Dependent Claim
20 words
A method according to claim 1, wherein said multilayer structure is formed by means of a multilayer screen printing technique.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-09 | 1990-08-11 | 1991-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-09 | 1994-08-11 | 1995-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-09 | 1998-08-11 | 1999-02-10 | $7700.00 | Window Closed / Lapsed |