Composite solders

Abstract

The characterization of composite solders has been performed, specifically on tin/lead/Cu/sub 6/Sn/sub 5/ composition. This characterization includes both microstructural and mechanical analysis. Scanning electron microscope (SEM) characterization of cross sections of the composite solder was preferred over optical inspection, owing to the similar appearance of the Sn and Cu/sub 6/Sn/sub 5/ phases by the latter method. The mechanical properties of composites were examined and were found to be superior those of standard tin/lead solder. Melting points of composite solder were the same as 60/40 tin/lead solder. Solder joints were readily prepared using the composite solder and were forced to failure by thermocyclic fatigue. The mechanism of failure was the same as for 60/40 Sn/Pb solder, i.e. heterogeneous coarsening. Auger/ESCA analysis of the intermetallic was performed to ascertain the nature of the surface of this filler, and it was found to be enriched in tin.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>