Microstructure and mechanical characteristics of a novel Cu/Cu3Sn joint with Cu/Sn preform

In this study, microstructure and mechanical characteristics of Cu/Cu3Sn composite joint based on Cu/Sn core-shell micoroparticles was systematically investigated. Cu/Sn system joint structure was well-designed, in which the Cu/Sn ratio was theoretically maintained with the Cu/Sn mass ratio greater than 3: 1 and Sn coating layer thickness was less than 0.206 times of Cu particle radius to obtain CU
3
Sn matrix with a dispersion of ductile Cu in the joint. Growing dynamics of CU
3
Sn in Cu/Cu3Sn structure was deeply analyzed, indicating the lower activity energy of CU
3
Sn than that of traditional solder alloys, which make rapid formation of the joint. When the average grain diameter of Cu particle was 25 μm, the microstructure evolution and shear strength of
$\text{Cu}/\text{Cu}_{3}\text{Sn}$
bulk with Sn coating
$\text{thickness} < 1\mu \mathrm{m},1\sim 2\mu \mathrm{m}$
and
$2\sim 2.5\mu\mathrm{m}$
were experimentally studied, respectively, indicating that the Cu/Sn system with
$1\sim 2\mu \mathrm{m}$
Sn coating layer has the dense joint and the largest shear strength. Zigzag fracture mechanism of Cu/Cu3Sn joint was originated the different volume shrinkage ratio of planar and 3D network structure.