Browse Prior Art Database

Pretinning the Metallurgy of a Module to Enhance Wettability

IP.com Disclosure Number: IPCOM000088652D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Pottier, B: AUTHOR

Abstract

Described is a method of pretinning the surface of a module to permit checking its wettability.

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Pretinning the Metallurgy of a Module to Enhance Wettability

Described is a method of pretinning the surface of a module to permit checking its wettability.

The substrate of a module provided with metal pads is first covered with a flux. A powder, consisting of a mixture of Pb-Sn or Pb-In (1 vol.) and alumina (1 or 2 vol.), is then deposited over the surface of the substrate through a screen or mask (Fig. 1). The module is then heated in a nitrogen atmosphere to cause the powder to melt. The melted powder wets the metal pads and forms minute balls on the unwetted surface of the ceramic substrate (Fig. 2). The excess powder is then removed by means of a conventional cleaning step involving the use of, for example, organic solvents.

This method enables a metal layer of any thickness from a few microns up to over 50 microns to be formed according to powder size and composition.

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