Cu3Sn joint based on transient liquid phase bonding of Cu@Cu6Sn5 core–shell particles
Jintao Wang, Jianqiang Wang, Fangcheng Duan, Hongtao Chen, Fangcheng Duan, Hongtao Chen
Abstract
Abstract With the development of high-integration and high-power electronics, the lack of matching chip connecting materials that can withstand high temperatures has been a challenge. In this manuscript, a Cu@Cu 6 Sn 5 core–shell bimetallic particles (approx. 1 μm in diameter) are successfully prepared and introduced as a new solder material for the packaging of power devices to obtain a Cu 3 Sn all-IMC solder joint. The joint consisted mainly of equiaxed Cu 3 Sn grains, and a small portion of columnar Cu 3 Sn grains. In columnar-type growth, Sn is the dominant diffusing species, which comes from the depletion of Sn in Cu 6 Sn 5 . The depleted Cu 6 Sn 5 is transformed into columnar Cu 3 Sn. In equiaxed-type growth, Cu is the dominant diffusing species. Cu reacts with Cu 6 Sn 5 to grow a Cu 3 Sn layer. This conclusion was confirmed by the orientation relationship. The equiaxed Cu 3 Sn grain nucleates at the Cu/Cu 3 Sn interface have an orientation relationship with the Cu substrate. Columnar Cu 3 Sn grains at the Cu 6 Sn 5 /Cu 3 Sn interface have an orientation relationship with Cu 6 Sn 5 .