Solders as high temperature engineering materials

Abstract

Although they operate at temperatures around ambient, it is argued that tin-based solders may be regarded as conventional high temperature engineering alloys, such as steels, titanium and nickel-base alloys, which normally experience much higher temperatures. This proposition is based upon a comparison at similar homologous temperatures, rather than their absolute values.

The demand for structural integrity of soldered joints in modern electronic devices is growing. Design challenges, quite similar to those in power generation and aerospace, require reliable life prediction under complex operating conditions. The paper compares monotonic and cyclic properties of solders with those of the more conventional high temperature alloys. Particular attention is focussed on the emerging lead-free solders which are being introduced for environmental reasons. It is concluded that solders are amongst the most vulnerable of high temperature alloys particularly with respect to their strain rate sensitivity and time dependent behaviour.