US3740819A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of reducing the incidence of short circuits on air isolated beam crossovers
Assignee: AT&T Inc
•
Filing: 1970-12-21
•
Granted: 1973-06-26
•
Expires: 1990-12-21
Abstract
Abstract Deposited thin film circuitry having a large number of airisolated crossovers is treated to reduce potential rejects because of crossover short circuits by causing the evolution of gas within a liquid in the region under the crossovers at a rate sufficient to lift the crossover beams without fracture, as by the reaction of a dilute acid with a bicarbonate or by the vigorous boiling of a volatile liquid such as alcohol, acetone or xylene, or by expanding initially liquid materials under the beam. The effectiveness is enhanced by a preliminary heating of the crossovers to a temperature above about 250* C.
Inventors
- 👤 D Babusci
- 👤 B Unger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:31
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/46; H05K3/4685; H10; H10N; H10N97/00; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49121; Y10T29/49805
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
32 words
The method of claim 1 wherein the evolution of gas is accomplished by reacting, in said space, a bicarbonate and an acid which decomposes said bicarbonate to cause evolution of carbon dioxide.
Claim 2
Dependent Claim
54 words
The method of claim 1 wherein the evolution of gas is accomplished by applying a slurry of ammonium bicarbonate in water to the surface of said substrate which is maintained at reduced atmospheric pressure and an aqueous solution of an acid is applied to said surface while it is maintained at reduced atmospheric pressure.
Claim 3
Dependent Claim
11 words
The method of claim 3 wherein the acid is acetic acid.
Claim 4
Dependent Claim
24 words
The method of claim 1 wherein the crossovers are first heated to a temperature of at least 250* C. and then allowed to cool.
Claim 5
Dependent Claim
32 words
The method of claim 1 wherein, in addition to the gas evolution treatment, the crossovers are subjected to the action of an etchant for the metal of which the crossovers are formed.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |