“…The viscoplastic damage, measured by indicators such as strain energy density and plastic work, accumulates cycle by cycle and eventually culminates in solder joint failure through fatigue cracking mechanism. Metallurgical reactions involving solder alloys, copper in the bond pad and pad metalisation during both reflow assembly process and life operations produce and grow IMC respectively at the interfaces of solder bulk and the bond pads [12,[16][17][18][19][20][21]. The lead-free solder used in FC manufacture contains Sn3.9Ag0.6Cu alloy materials [22].…”