Browse Prior Art Database

Joining Electrical Components

IP.com Disclosure Number: IPCOM000092348D
Original Publication Date: 1967-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Herdzik, RJ: AUTHOR [+2]

Abstract

This method eliminates the erosion of printed circuitry and like structures by solder during solder dipping and solder reflow process steps.

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This is the abbreviated version, containing approximately 89% of the total text.

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Joining Electrical Components

This method eliminates the erosion of printed circuitry and like structures by solder during solder dipping and solder reflow process steps.

In the fabrication of hybrid microminiaturized electronic modules, it is conventional to apply a solder wettable conductive paste to a ceramic module in the form of the printed circuit. Then the printed module is dipped in molten solder to form the metal conductor. A typical paste can include gold or silver and platinum and/or palladium or their alloys.

The paste can be eroded by the solder during subsequent solder reflow cycles necessary to package the module. In the backside joining of semiconductor devices to the module, laminar layers of chromium, copper, and gold, respectively, are applied to the device backside. The resultant unit is joined to a solder pad on a module. Occasionally unacceptable voids and a loss of film integrity occur.

This method provides a layer of electroless nickel over the metallurgy prone to solder erosion. In protecting the electrode paste in printed circuit patterns, a layer of electroless gold can be applied. Such application uses a steel or nickel screen in contact with all the circuits to establish continuity and provide a catalyst to the plating action. The module can then be transferred to an electroless nickel bath where nickel is plated over the gold using basically the same technique.

The module is then solder-dipped in the conventional manner. In backside ...