US3798060A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods for fabricating ceramic circuit boards with conductive through holes
Assignee: Westinghouse Electric Corp
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Filing: 1971-10-28
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Granted: 1974-03-19
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Expires: 1991-10-28
Abstract
Abstract A method for preparing double-sided circuit boards for electrical circuits wherein a ceramic substrate containing a plurality of holes is metallized by chemical vapor deposition of tungsten on the surface and through the holes and is etched delineate conductive patterns. There is also provided the product produced by this process. The process is preferably used on electronic microcircuits with alumina or beryllia substrates where electrical interconnections between conductive patterns the two outer surfaces and between the outer surfaces and the innerlayers are provided by through-hole metallization.
Inventors
- 👤 W Reed
- 👤 R Stoltz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:25
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/40; H05K3/4038; H05K3/4076; H05K3/10; H05K3/14; H05K3/146; H05K3/02; H05K3/06; H05K3/061; H05K3/062; H05K3/108
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
26 words
The method as specified in claim 1, wherein said ceramic comprises beryllia and said tungsten halide consists essentially of at least one of WCl6 and WF6.
Claim 2
Dependent Claim
25 words
The method as specified in claim 1, wherein said ceramic comprises alumina and said tungsten halide consists essentially of at least one WCl6 and WF6.
Claim 3
Dependent Claim
119 words
The method as specified in claim 3, wherein: a. said patterning comprises; coating said substrate with photoresist, exposing said photoresist with a predetermined pattern of light, and developing said photoresist and thereby exposing some portions of said tungsten; b. before etching said coated and patterned substrate, electroplating a predetermined thickness of nickel and then a predetermined thickness of gold onto said exposed portions of said tungsten; and c. after electroplating but before etching, removing said photoresist such that tungsten which is not covered by nickel and gold may be etched away in the subsequent etching step, d. said etching is done with a solution of H2O2 and an approximately equal proportion of at least one of KOH and NaOH.
Claim 4
Dependent Claim
81 words
The method as specified in claim 3, wherein: a. prior to patterning said coated substrate, electroplating said substrate with a predetermined thickness of nickel; b. said patterning comprises coating said substrate with a dry film photoresist, exposing said photoresist with a predetermined pattern of light, and developing said photoresist and thereby exposing some portions of said electroplated nickel during the subsequent etching step; and c. after etching, immersing said substrate into replacement gold solution and thereby coating said nickel with gold.
Claim 5
Dependent Claim
38 words
The method as specified in claim 1, where said ceramic contains an innerlayer of patterned conductive material and said tungsten through-hole metallization is used to provide electrical connections between said conductive innerlayers and surface conductors delineated by etching.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |