US4640739A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of producing galvanic layers of solder of precise contour on inorganic substrates
Assignee: Robert Bosch GmbH
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Filing: 1985-08-15
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Granted: 1987-02-03
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Expires: 2005-08-15
Abstract
Abstract Very fine solder-coated conduction paths are made on ceramic, glass or enamel substrates by the combination of a first step in thick-film technology followed by the photo-masking and etching steps typical of thin-film technology, after which galvanic reinforcement of the initial calcined copper paste layer is performed in the locations where the initial layer is exposed by the developed mask. A lead-tin solder layer is then galvanically deposited, which is thicker than the mask, after which the mask is removed and the newly exposed portions of the initial copper layer are etched away. A reflow treatment of the solder layer pattern consolidates the solder layer by melting on top of the boundaries of the unetched initial copper layer. It is possible to obtain conduction path spacings down to 50 μm with conduction paths coated with solder that have excellent adhesion to ceramic, glass or enamel substrates.
Inventors
- 👤 Fedor Modic
- 👤 Wolfgang Leibfried
- 👤 Manfred Nitsch
- 👤 Kurt Spitzenberger
- 👤 Herbert Zimmermann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:37
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H05K3/245; H05K3/246; C; C25; C25D; C25D5/00; C25D5/54; H05K3/10; H05K3/108; H05K3/30; H05K3/32; H05K3/34; H05K3/3465; H05K3/3473; H05K1/00; H05K1/02; H05K1/03; H05K1/0306; H05K1/09; H05K1/092; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0335; H05K2201/0347; H05K2203/00; H05K2203/04; H05K2203/043; H05K2203/07; H05K2203/0703; H05K2203/0723; H05K3/02; H05K3/06; H05K3/061; H05K3/062
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
204 words
Process for producing contoured solder layers overlying a copper layer on a surface of an inorganic substrate which is an electrical insulator composed predominantly of oxide material, comprising the steps of: applying over an entire surface of said substrate, and then calcining, a conducting copper paste to form a conducting and adhesion-promoting copper first layer (2) on said substrate; superposing on said copper layer a photoresist film (3) and a negative image film of a desired pattern on top of said photoresist film, followed by exposing said photoresist film, through said negative image film, to illumination, developing said photoresist film and hardening the same in said desired pattern; galvanically reinforcing the portion of said copper first layer not covered by said photoresist film with at least one layer (4) of a conducting layer composed of metallic material selected from the group which consists of copper and nickel; galvanically depositing, on top of said at least one reinforcing layer, a layer (5) of lead-tin solder; removing said hardened photoresist film; etching away said copper first layer in the locations where said hardened photoresist film was removed, and melting said solder layer for conforming its contour to the underlying unetched remainder of said copper first layer.
Claim 2
Dependent Claim
204 words
Process for producing contoured solder layers overlying a copper layer on a surface of an inorganic substrate which is an electrical insulator composed predominantly of oxide material, comprising the steps of: applying over an entire surface of said substrate, and then calcining, a conducting copper paste to form a conducting and adhesion-promoting copper first layer (2) on said substrate; superposing on said copper layer a photoresist film (3) and a negative image film of a desired pattern on top of said photoresist film, followed by exposing said photoresist film, through said negative image film, to illumination, developing said photoresist film and hardening the same in said desired pattern; galvanically reinforcing the portion of said copper first layer not covered by said photoresist film with at least one layer (4) of a conducting layer composed of metallic material selected from the group which consists of copper and nickel; galvanically depositing, on top of said at least one reinforcing layer, a layer (5) of lead-tin solder; removing said hardened photoresist film; etching away said copper first layer in the locations where said hardened photoresist film was removed, and melting said solder layer for conforming its contour to the underlying unetched remainder of said copper first layer.
Claim 3
Dependent Claim
48 words
Process according to claim 1, in which said conducting copper paste is composed of powdered copper, a dispersing agent, powdered glass and copper oxide in the form of a substance selected from the group consisting of Cu 2 O, CuO and mixtures of Cu 2 O and CuO.
Claim 4
Dependent Claim
48 words
Process according to claim 1, in which said conducting copper paste is composed of powdered copper, a dispersing agent, Pb0 and copper oxide in the form of a substance selected from the group consisting of Cu 2 O and CuO and mixtures of Cu 2 O and CuO.
Claim 5
Dependent Claim
51 words
Method according to claim 1, in which said conducting copper paste is composed of powdered copper, a dispersing agent, glass powder, bismuth oxide and copper oxide in the form of a substance selected from the group consisting of Cu 2 O and CuO and mixtures of Cu 2 O and CuO.
Claim 6
Dependent Claim
50 words
Process according to claim 1, in which said conducting copper paste is composed of powdered copper, a dispersing agent, Pb0, bismuth oxide and copper oxide in the form of a substance selected from the group consisting of Cu 2 O and CuO and mixtures of Cu 2 O and CuO.
Claim 7
Dependent Claim
36 words
Process according to claim 1, in which said conducting copper paste is applied on said substrate in such a thickness that after calcining said copper first layer as a thickness of from 5 to 12 μm.
Claim 8
Dependent Claim
19 words
Process according to claim 6, in which said conducting copper paste is applied on said substrate by screen printing.
Claim 9
Dependent Claim
32 words
Process according to claim 1, in which the calcining of said conducting copper paste is carried out in a nitrogen atmosphere at a temperature in the range from 900° to 950° C.
Claim 10
Dependent Claim
22 words
Process according to claim 1, in which said photoresist film (3) has a thickness in the range from 25 to 70 μm.
Claim 11
Dependent Claim
28 words
Process according to claim 1, in which said at least one layer reinforcing said copper first layer has a thickness in the range from 3 to 12 μm.
Claim 12
Dependent Claim
23 words
Process according to claim 1, in which said layer of lead-tin solder has a thickness in the range from 20 to 60 μm.
Claim 13
Dependent Claim
24 words
Process according to claim 1, in which the step of removing said photoresist film is performed by dissolving it away in an organic liquid.
Claim 14
Dependent Claim
44 words
Process according to claim 1, in which said photoresist film is a film which is strippable by means of an alkaline reagent and in which the step of removing said photoresist film is carried out stripping by means of an alkali metal hydroxide solution.
Claim 15
Dependent Claim
43 words
Process according to claim 1, in which the step of etching away said copper first layer in the locations where said hardened photoresist film was removed is performed with an ammoniacal etching solution, while said galvanically deposited solder layer functions as an etch-resist.
Claim 16
Dependent Claim
22 words
Process according to claim 1, in which the step of melting said solder layer is carried out in a protective gas atmosphere.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |