Abstract:The performance of resistance to hot and cold cycle of a new low silver solder paste SnAgCuBiNi (SACBN07) and SAC305 solder paste on the market were compared and analyzed. The shear strength and nanohardness of micro solder joints before and after hot and cold cycles were compared

and the effect of trace elements on the microstructure of the interface and mechanical properties was analyzed. The results show that the shear strength and nanoindentation hardness of SACBN07 are higher than that of SAC305 due to the solid solution strengthening and dispersion strengthening of Bi element in SACBN07. Because of the shear strength of SACBN07 and the nanoindentation hardness of bulk solder affected little by hot and cold cycles

the hardness of solder joint is reduced by 17.4% and the shear strength is decreased by 15.3% on the SACBN07 solder joint after 600h hot and cold cycle

while the SAC305 solder hardness decreased by 31.3%

the shear strength decreased by 23%.The Ni element added in SACBN07 solder paste slows down the growth rate of the interfacial compound

and the thickness of the IMC layer on the SACBN07 solder joint is less than that of SAC305 solder joint after 600h hot and cold cycle. In a word

we get that the performance of SACBN07 solder paste is better than that of SAC305 solder paste.