US3867217A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods for making electronic circuits
Assignee: AT&T Inc
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Filing: 1973-10-29
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Granted: 1975-02-18
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Expires: 1993-10-29
Abstract
Abstract In a technique for forming thin-film circuits by laser machining, the gold conductor layer is first covered with a copper protective layer. After machining, the laser-machined gaps are cleaned by a fluid stream containing abrasive particles, during which operation the protective layer shields the gold conductors. Thereafter, the protective layer is removed by selective etching.
Inventors
- 👤 Charles Maggs
- 👤 Walter Werner Weick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:14
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/02; H05K3/027; B; B23; B23K; B23K26/00; B23K26/18; H10; H10N; H10N97/00; H05K1/00; H05K1/02; H05K1/03; H05K1/0306; H05K2201/00; H05K2201/03; H05K2201/0302; H05K2201/0317; H05K2203/00; H05K2203/02; H05K2203/025; H05K2203/03; H05K2203/0361
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
156 words
IN A METHOD FOR MAKING ELECTRONIC CIRCUITS, THE IMPROVEMENT COMPRISING THE STEPS OF: FORMING A FIRST METAL LAYER ON A SURFACE OF A SUBSTRATE; FORMING A SECOND METAL LAYER OVER THE FIRST LAYER, THE SECOND LAYER BEING OF A DIFFERENT METAL FROM THAT OF THE FIRST LAYER; DEFINING A CIRCUIT COMPRISING THE STEP OF EVAPORATING WITH A LASER BEAM A PORTION OF THE FIRST AND SECOND LAYERS THEREBY TO EXPOSE AT LEAST ONE AREA OF THE SUBSTRATE SURFACE; CLEANING THE EXPOSED SUBSTRATE SURFACE AREA COMPRISING THE STEP OF DIRECTING A FLUID STREAM CONTAINING ABRASIVE PARTICLES AGANIST THE SECOND LAYER AND SAID AREA, THE FLUID STREAM BEING SUFFICIENTLY ABRASIVE TO CLEAN THE SUBSTRATE SURFACE AREA AND TO ERODE PART OF THE SECOND LAYER, BUT NOT SUFFICIENTLY ABRASIVE TO PENETRATE THROUGH THE SECOND LAYER; AND SELECTIVELY DISSOLVING THE SECOND LAYER BY EXPOSING IT TO A METAL ETCHANT WHICH DOES NOT SIGNIFICANTLY AFFECT THE METAL OF THE FIRST LAYER.
Claim 2
Dependent Claim
156 words
IN A METHOD FOR MAKING ELECTRONIC CIRCUITS, THE IMPROVEMENT COMPRISING THE STEPS OF: FORMING A FIRST METAL LAYER ON A SURFACE OF A SUBSTRATE; FORMING A SECOND METAL LAYER OVER THE FIRST LAYER, THE SECOND LAYER BEING OF A DIFFERENT METAL FROM THAT OF THE FIRST LAYER; DEFINING A CIRCUIT COMPRISING THE STEP OF EVAPORATING WITH A LASER BEAM A PORTION OF THE FIRST AND SECOND LAYERS THEREBY TO EXPOSE AT LEAST ONE AREA OF THE SUBSTRATE SURFACE; CLEANING THE EXPOSED SUBSTRATE SURFACE AREA COMPRISING THE STEP OF DIRECTING A FLUID STREAM CONTAINING ABRASIVE PARTICLES AGANIST THE SECOND LAYER AND SAID AREA, THE FLUID STREAM BEING SUFFICIENTLY ABRASIVE TO CLEAN THE SUBSTRATE SURFACE AREA AND TO ERODE PART OF THE SECOND LAYER, BUT NOT SUFFICIENTLY ABRASIVE TO PENETRATE THROUGH THE SECOND LAYER; AND SELECTIVELY DISSOLVING THE SECOND LAYER BY EXPOSING IT TO A METAL ETCHANT WHICH DOES NOT SIGNIFICANTLY AFFECT THE METAL OF THE FIRST LAYER.
Claim 3
Dependent Claim
13 words
The improvement of claim 1 wherein: the second layer is a copper layer.
Claim 4
Dependent Claim
12 words
The improvement of claim 2 wherein: the substrate is a ceramic substrate.
Claim 5
Dependent Claim
13 words
The improvement of claim 3 wherein: the first layer is a gold layer.
Claim 6
Dependent Claim
30 words
The improvement of claim 4 wherein: the step of forming the second layer comprises the step of depositing copper to a thickness on the order of 2 to 4 microns.
Claim 7
Dependent Claim
24 words
The improvement of claim 5 wherein: the abrasive particles are aluminum oxide particles having diameters in the approximate range of 10 to 27 microns.
Claim 8
Dependent Claim
32 words
The improvement of claim 6 wherein: the defining step comprises the step of removing a plurality of portions of metal; each portion being defined by a plurality of overlapping laser machined spots.
Claim 9
Dependent Claim
33 words
The improvement of claim 7 wherein: the step of laser machining comprises the step of projecting a light beam having a wavelength on the order of 1.06 microns from a neodymium YAG laser.
Claim 10
Dependent Claim
31 words
The improvement of claim 8 further comprising the step of: immersing the substrate surface in a phosphoric acid solution for about one minute prior to the removal of the second layer.
Claim 11
Dependent Claim
15 words
The improvement of claim 9 wherein: the metal etchant is a solution of ferric chloride.
References Cited (Backward Citations)
US3258898A
Cited
US3668028A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |