Claims
- 1. A method of forming a printed circuit comprising:
- providing a resinous substrate,
- bonding a composite metal structure to said substrate, said metal structure including a layer of copper foil having opposed first and second surfaces and a thin layer of nickel having opposed first and second surfaces with one of said surfaces of said copper foil being bonded to one of said surfaces of said nickel layer and the opposite opposed surface of said nickel layer being bonded to said resinous substrate, said nickel layer containing an effective amount of sulfur to render said copper foil and said nickel barrier layer mutually etchable, and
- etching said circuit into said composite metal structure by means of an etchant which mutually dissolves selected portions of said copper foil and said nickel barrier layer.
- 2. The method of claim 1 in which said nickel barrier layer contains from about 0.05 to about 10.0 weight percent sulfur.
- 3. The method of claim 2 wherein said sulfur is present in an amount in excess of about 0.05 weight percent.
- 4. The method of claim 2 wherein said etchant is selected from the group consisting of ferric chloride, ammonium persulfate, cupric chloride and a mixture of chromic-sulfuric acid.
- 5. The method of claim 1 wherein said sulfur is present in an amount in excess of 2.0 weight present.
- 6. The method of claim 5 wherein said etchant is an alkaline etch.
Parent Case Info
This is a division, of application Ser. No. 863,109, filed Dec. 22, 1977, now U.S. Pat. No. 4,190,474.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
863109 |
Dec 1977 |
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