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NON-Au LOW TEMPERATURE BRAZE ALLOY: Ag-Cu-Sb-(Sn, In)

IP.com Disclosure Number: IPCOM000036427D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brofman, PJ: AUTHOR [+3]

Abstract

In chip joining during the manufacture of semiconductor modules a braze alloy with a solidus temperature above the 370oC maximum processing temperature is desirable. Available alloys in the 370oC-450oC range are Au-based which adds costs to the manufacturing process. This article proposes alloys based on Sn and/or In additions to an Ag-Cu-Sb eutectic which would provide low-cost, high melting point brazing.

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NON-Au LOW TEMPERATURE BRAZE ALLOY: Ag-Cu-Sb-(Sn, In)

In chip joining during the manufacture of semiconductor modules a braze alloy with a solidus temperature above the 370oC maximum processing temperature is desirable. Available alloys in the 370oC-450oC range are Au- based which adds costs to the manufacturing process. This article proposes alloys based on Sn and/or In additions to an Ag-Cu-Sb eutectic which would provide low-cost, high melting point brazing.

The eutectic is composed of 44.3% Ag, 13.3% Cu and 42.4% Sb by weight. It melts at 425oC. Changes in its solidus and liquidus temperatures with the addition of Sn and In are given below: Additions to Solidus
Liquidus
Ag-Cu-Sb Eutectic Temperature (oC) Temperature(oC 5 Sn 400 419

10 Sn 383 408

5 In 390 424

10 In 392 417

5Sn/5In 380 407

The liquidus-solidus region is fairly narrow. There is the possibility that changing ratios of Ag, Cu, Sb would decrease the temperature range of this mushy region.

The reaction of the alloys with Cu and Ni was studied by holding them at 500oC for 1/2 hour under H2 . In general, Cu reacted to a much greater degree than Ni. The thickness of the reaction region ranged from 0.006 in.-0.018 in. for Cu compared to 0.0005 in.-0.003 for nickel, indicating the latter would be better for bonding with these alloys.

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