1831 鉛フリーはんだのメカニカルラチェット変形特性  [in Japanese] Mechanical Ratchetting of Lead-Free Solder Alloys  [in Japanese]

Deformations of the solder alloys used for solder joints due to cyclic thermal condition is governed by ratchetting deformation. Then simulations of the ratchetting deformation are required for the accurate reliability design of lead-free board level packaging. This paper performed experimental studies of the mechanical ratchetting deformation of lead-free solder alloys. Since the mechanical ratchetting is dominated by viscosity of materials, additional creep tests after the mechanical ratchetting deformation is also discussed. The interaction between mechanical ratchetting and creep deformation is clarified from the difference of the additional creep deformation due to the number of cycles of the primary mechanical ratchetting. Sn-3Ag-0.5Cu is chosen for the lead-free solder alloy, while Sn-37Pb for the lead solder alloy.