Microstructure and shear strength of solder joints of SiC_p/Al composites with Ni plating with Sn-2.5Ag-2.0Ni solder

An experimental study was presented to evaluate the microstructures and reliability of solder joints between Sn-2.5Ag2.0Ni solder and various Ni plating layers. Ni(P)/Ni(B) and Ni(P)/Ni double layers were used to deposit on SiC_p/Al composites. The high reaction rate between Ni(B) layer and SnAgNi solder leaded to the highest growth rate of intermetallic compound (IMC) Ni₃Sn₄. The shear strength of solder joints with Ni(P)/Ni layer is higher than that of solder joints with Ni(P)/Ni(B) layer at the initial stage of aging, but lower than that after 250 h aging.Intermetallic layer growth and crack formation are the major reasons of failure for a SnAgNi/Ni/Ni(P) solder joint. While the failure of a SnAgNi/Ni(B)/Ni(P) solder joint is caused by the formation of holes between Ni(P) and SiC_p/Al composites, which result from directional diffusion of Ni toward solder.