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Browse Prior Art Database

Joining Chip to Substrates in Oxygen Containing Atmosphere

IP.com Disclosure Number: IPCOM000089553D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brunner, J: AUTHOR [+5]

Abstract

In the manufacture of a circuit module in which solder balls connect a semiconductor chip to conductive pads on a ceramic substrate, the unsoldered assembly is placed in an oven that is operated at a suitable temperature to melt the solder. The oven conventionally has an atmosphere of an inert gas, such as nitrogen. The solder joint can be improved by conducting the soldering operation in an atmosphere containing small amounts of oxygen. About six thousand parts per million produces improved solder joints.

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Joining Chip to Substrates in Oxygen Containing Atmosphere

In the manufacture of a circuit module in which solder balls connect a semiconductor chip to conductive pads on a ceramic substrate, the unsoldered assembly is placed in an oven that is operated at a suitable temperature to melt the solder. The oven conventionally has an atmosphere of an inert gas, such as nitrogen. The solder joint can be improved by conducting the soldering operation in an atmosphere containing small amounts of oxygen. About six thousand parts per million produces improved solder joints.

The probable mechanism of this improvement is that a layer of oxide a few hundred angstroms thick is formed on the solder and that this layer protects the underlying solder from contaminants. The thickness of the layer is a function of the oxygen concentration, the temperature of the oven, and the activation energy of the materials. The value of the oxygen concentration is chosen to produce an oxide film that is thick enough to cover the solder but not to form a thick layer that may be brittle.

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