Growth behavior of compounds at Sn3.5Ag0.5Cu/Ni under thermal-shearing cycling

The atoms diffusion and growth behavior of intermetallic compound (IMC)at Sn3.5Ag0.5Cu/Ni interface after thermal-shearing cy cling (25-125℃)were investigated, which was compared to compound growth behavior under isothermal aging condition. The results showed that there is a type of (Cu_xNi_1-x)₆Sn₅ IMC formed at the interface after reflowing, and the morphology of compound changes from scallop-like with the cycling increasing. There is another kind of compound (Ni_xCu_1-x)Sn₃ formed surrounding (Cu_xNi_1-x)₆Sn₅ after 200 cycles and grow up rapidly as planarlike.As the thermal-shearing cycling increasing, Ag₃Sn formed uniform particles after reflowing congregates to grow up to chunk-like in the solder.The IMC at the interface growth follows a parabolic growth kinetiscs with the thermal-shearing cycling increasing, implying that it was controlled by Cu atom diffusion.