Cu-Sn based die attach material for power semiconductor with stress control

This paper describes development of joint materials using only base metals (Cu and Sn) for power semiconductor assembly. The preform sheet of the joint material is made by two kinds of particles such as Cu source and Cu-Sn IMC source. Optimized ratio of Cu source: IMC source provides robust skeleton structure in joint area. The particles' mixture control (Cu density and thickness) affects stress control to eliminate cracks and delamination of the joint area. As evaluation, Thermal Cycling Test (TCT, -40°C~+200°C, 1,000cycles) of Cu-Cu joint resulted no critical cracks / delamination / voids. We confirmed the material also applicable for attaching SiC die on the DCB substrate on bare Cu heatsink.