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US 5,235,139 AGranted
Method for fabricating printed circuits
AssigneeMacDermid, Incorprated
InventorsJon E. Bengston, Gary B. Larson
Life of this patent
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AssigneeMacDermid, Incorprated
InventorsJon E. Bengston, Gary B. Larson
Estimating the term…
Conductive copper areas of printed circuits, such as through-holes, pads and lands, to which electronic components can thereafter be electrically connected by, e.g., wave soldering, are provided with a coating of nickel or cobalt, such as by electroless deposition from nickel-or cobalt-boron and nickel-or cobalt-phosphorous plating baths, or entirely or partly electrolytically, followed by a coating of a protective material which protects the nickel or cobalt coating from oxidation prior to the subsequent solder connection operation, is wettable by solder in the subsequent solder connection operation, and substantially dissolves in the solder in the subsequent solder connection operation without adverse effect on the solder joint between the electronic component and the through-hole, pad or land. A particular preferred protective material is gold, such as applied by deposition from immersion or electroless gold plating baths. The invention renders the so-treated areas readily susceptible to the soldering of components thereat, thereby avoiding the need for hot air solder levelling.
In a printed circuit comprising conductive areas affixed to an insulating substrate, said conductive areas including particular exposed conductive surfaces to which electronic components are to be electrically connected by soldering, the improvement wherein the particular exposed conductive surfaces comprise:
In a printed circuit comprising conductive areas affixed to an insulating substrate, said conductive areas including particular exposed conductive surfaces to which electronic components are to be electrically connected by soldering, the improvement wherein the particular exposed conductive surfaces comprise:
In a process for fabricating a printed circuit having conductive areas affixed to an insulating substrate, and wherein particular ones of said conductive areas include areas having exposed copper surfaces and selected from the group consisting of through-hole surfaces, surrounding pads, lands, and combinations thereof, which are provided in the printed circuit for later connection thereto, by soldering, of electronic components, the improvement comprising:
Dependencies are inferred from the claim text.