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SELECT Au/Sn/Cu ALLOYS FOR TERMINAL PIN BRAZE

IP.com Disclosure Number: IPCOM000047572D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Ainslie, NG: AUTHOR [+4]

Abstract

There is need in some processes for brazing terminal pins to electronic components for a higher melting (than 80% Au/20% Sn) pin braze alloy. Alloys of Au/Sn/Cu have been mentioned as being used for brazing electronic packages. However, there is an infinite number of alloys in the Au/Sn/Cu system with an infinite number of properties. What is described here is a select number of Au/Sn/Cu alloys with properties suitable for MLC (multilayer ceramic) pin brazing, as described in Table 1. Pin brazing is generally done for Au/Sn/Cu alloys up to a peak temperature of 175ŒC above the solidus with a 6-10 minute dwell (considerably longer than 80% Au/20% Sn alloy) at a temperature of 125ŒC above the solidus. Forming gas or hydrogen can be used as the brazing atmosphere.

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SELECT Au/Sn/Cu ALLOYS FOR TERMINAL PIN BRAZE

There is need in some processes for brazing terminal pins to electronic components for a higher melting (than 80% Au/20% Sn) pin braze alloy. Alloys of Au/Sn/Cu have been mentioned as being used for brazing electronic packages. However, there is an infinite number of alloys in the Au/Sn/Cu system with an infinite number of properties. What is described here is a select number of Au/Sn/Cu alloys with properties suitable for MLC (multilayer ceramic) pin brazing, as described in Table 1. Pin brazing is generally done for Au/Sn/Cu alloys up to a peak temperature of 175OEC above the solidus with a 6-10 minute dwell (considerably longer than 80% Au/20% Sn alloy) at a temperature of 125OEC above the solidus. Forming gas or hydrogen can be used as the brazing atmosphere. In Table 2 below are other Au/Sn/Cu alloys which were brazed similarly to those in Table 1. In addition to the properties given in Table 1, failure modes are given. The alloys with higher Sn and Cu compositions fracture at a weak interface between the braze and Ni-plate of the pin. Negligible reaction was observed between the braze and Ni. These alloys, not suitable for bonding to Ni, may bond well to other materials, e.g., Cu, used for attachment bases. The results of Table 2 are summarized in Fig. 1. Fig. 1 is a portion of the ternary Au- Sn-Cu phase diagram where the failure modes are plotted. The higher Au alloys with pin fail are separated from the highe...