Development of transient liquid phase soldering process for LSIdie-bonding

摘要

For high-power semiconductor devices with Cu lead-frames inplastic packages, die-bonding process that can obtain a heat-resistantbond (with high melting point) without large residual stress has beendeveloped by applying transient liquid-phase bonding to the solderingprocess. A three-layered solder sheet the inner layer of which is95Pb-5Sn solder and the surface layers of which are Pb-Sn eutecticsolder is used as the bonding material. The bonding temperature is about460 K so as to melt only eutectic layers. The eutectic layers areisothermally solidified and the melting point of the bond rises to over520 K by a two-hour heat treatment at the bonding temperature. As aresult, a heat-resistant bond can be obtained whose residual stress canbe reduced by more than 1/2 by a low-temperature process