Tin pest in electronics?

摘要

Purpose - To review the literatures, and to consider the latest results regarding the formation of tin pest in lead-free solders and interconnections. Design/methodology/approach - Previous work, over almost a century, on tin pest formation in tin and its alloy has been critically analysed. Samples of the new generation of lead-free solders, which have experienced long term storage at - 18 and - 40℃, have been examined. Findings - Tin pest has been observed in bulk samples of tin - 0.5 (wt%) copper solder after exposure at - 18℃ although not at - 40℃. Other lead-free alloys (Sn-3.5Ag, Sn-3.8Cu-0.7Cu and Sn-Zn-Bi) have been immune to date. Large-scale model joints exhibit tin pest but actual joints may be resistant due to the limited free solder surface available and the constraint of intermetallic compounds and components. Research limitations/implications - The possibility of tin pest formation in joints remains. It seems that impurities are essential protection against it, but for long term applications there is no certainty that tin pest and joint deterioration will never occur. Originality/value - The paper considers the various factors that may affect tin pest formation and demonstrates its existence in one of the more popular new lead-free alloys.