Properties of two new medium temperature solders

Abstract

Purpose

The increasing utilization of Al‐matrix composites in electronics packaging industry raises demands of solder materials with melting temperature at 400‐500°C. The purpose of this paper is to determine the thermal properties of two Ag‐Cu‐Sb alloys with the composition close to two eutectic points, and two Au‐Ag‐Ge alloys along the eutectic line, to observe the microstructures and to investigate the wettability of the alloys, and to evaluate the possibility for them to be used as medium temperature solders.

Design/methodology/approach

Four candidates of solder alloys in the Au‐Ag‐Ge (AAG1, AAG2) and Ag‐Cu‐Sb systems (ACS1, ACS2) were studied to reveal microstructures, melting points, wettabilities, and the interfaces between the solder and Al/SiC substrate coated with Au and Ni.

Findings

The paper finds that the ACS1 and ACS2 alloys possess small temperature gaps between solidus and liquidus: 422.9°C/429.2°C and 483.3°C/488.1°C, respectively. For two AAG alloys, the temperature ranges between solidus and liquidus are larger than 40°C. The wettability tests showed that two ACSs and AAG1 alloys have good wettability to the substrate. Similarly, except ACS2 alloy, the other alloys exhibit good adhesion with the substrate.

Originality/value

The paper shows that the ACS1 alloy and the AAG1 alloy could be used as the optimum solder materials for 400‐500°C owing to the good wettability and proper melting point.

Citation

Li, C., Wang, X. and Yuan, W. (2009), "Properties of two new medium temperature solders", Soldering & Surface Mount Technology, Vol. 21 No. 2, pp. 4-8. https://doi.org/10.1108/09540910910947408