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Method for Fabricating Thin Braze Joint

IP.com Disclosure Number: IPCOM000038522D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Palmateer, PH: AUTHOR [+3]

Abstract

A proposal suggests the use of a thin braze joint to avoid stress caused by the high volume of Au/Sn braze used to braze pins to the bottom surface metallurgy (BSM) pads on the multilayer ceramic (MLC) module. The thin joint would relieve stresses which otherwise may lead to ceramic failures during pin pull tests. Pin pull tests on glass ceramic substrates indicate that the primary cause of ceramic cracking at low strength is due to the high stresses generated by the high volume Au-20 wt.%Sn eutectic braze. The utilization of a thin braze joint to avoid such stresses involves metallizing the BSM pads 1 (Fig. 1) on the glass ceramic substrate 2, followed by depositing a thicker Au layer 3 on either, or both, the surface of the pin 4 and the BSM pads. The Au layer may be deposited by evaporation, sputtering or plating.

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Method for Fabricating Thin Braze Joint

A proposal suggests the use of a thin braze joint to avoid stress caused by the high volume of Au/Sn braze used to braze pins to the bottom surface metallurgy (BSM) pads on the multilayer ceramic (MLC) module. The thin joint would relieve stresses which otherwise may lead to ceramic failures during pin pull tests. Pin pull tests on glass ceramic substrates indicate that the primary cause of ceramic cracking at low strength is due to the high stresses generated by the high volume Au-20 wt.%Sn eutectic braze. The utilization of a thin braze joint to avoid such stresses involves metallizing the BSM pads 1 (Fig. 1) on the glass ceramic substrate 2, followed by depositing a thicker Au layer 3 on either, or both, the surface of the pin 4 and the BSM pads. The Au layer may be deposited by evaporation, sputtering or plating. The Au-plated pins are next annealed to insure proper adhesion of the Au plating to the underlying metallurgy layer. A thin layer of Sn 5 is then deposited either on the pin head or on the BSM pads by means of evaporation, sputtering or immersion tinning. As an alternative approach, if the gold or tin layer is applied on the pin head, roll-cladding is an effective and low cost process. Finally, the use of a suitable brazing profile can effectively form the thin joint. Additionally, the use of thin joint together with a pin head diameter matching that of the BSM pad works most effectively in reducing braze stres...