High‐cycle fatigue testing of Pb‐free solder joints

Abstract

PurposeThe research aims to explore the high‐cycle fatigue performance of Pb‐free alloys and compare them to Sn‐Pb. In doing this, it also aims to demonstrate the viability of a new testing method.Design/methodology/approachThe method introduced uses existing test equipment in a novel way to combine the speed and applicability of general vibration testing with the control of single, model specimen testing. Model solder joints are constructed in a repeatable manner and repeated tensile stress cycles are applied until failure.FindingsIt is found that in the regime studied, all of the Pb‐free alloys tested show significantly decreased performance compared to Sn‐Pb, at ambient temperatures. No obvious mechanical or microstructural features have been identified as the cause of this discrepancy. The test method employed demonstrates good correlation with existing fatigue test methods despite the known variance of solder mechanical test results.Research limitations/implicationsIt is recognised that results pertaining to essentially only a one‐dimensional stress state are obtained, and that practical stresses will vary. The performance difference between Pb and Pb‐free alloys warrants further investigation.Originality/valueThe results obtained are of interest to high‐reliability electronics sectors such as aerospace, defence and automotive, where vibrations in service are encountered. Very little work exists on the subject of solder high‐cycle fatigue performance and to the author's knowledge none comparing Pb to Pb‐free alloys in an objective manner.

Reliability of Pb-free solders for harsh environment electronic assemblies

“…For harsh environments, vibrations can be a major issue. However, there is very little work that compares high cycle fatigue performance of Pb-free with Sn–Pb,28 probably because mechanical vibrations are considered a lesser issue for harsh environment applications, where traditional leaded packages are still being used. The rest of this review focuses on low cycle fatigue, generally considered to be the primary source of failure in electronic packages 29 29,30.…”

Solidification and wetting behaviour of SnAgCu solder alloyed by reactive metal organic flux

“…Coarsening changes the microstructure and thereby the mechanical properties of the solder significantly (Allen et al , 2004). Hence, many investigations have been carried out in order to analyse the thermal fatigue and creep properties of lead‐free solders (Henderson et al , 2004; Andersson et al , 2005; Liang et al , 1996; Barry et al , 2007).…”