Interfacial reactions of SAC305/Ni-P and SACBN/Ni-P were investigated at 403

433

463K for 100

400

700

1000hours.The results show that（Cu

Ni） 6Sn5 and（Ni

Cu）3Sn4 intermetallic compound layer are generated at the interface between the two solders and electroless Ni-P after isothermal aging;and the（Ni

Cu）3Sn4 appeares between the（Cu

Ni）6Sn5 layer and Ni-P layer.Meanwhile

with the increase of aging time or aging temperature

thickness of the IMC layer is increased.The growth rate o f the intermetallic layers of the SACBN/Ni-P is a slightly hgiher than that of the SAC305/Ni-P during aging

and the growth rate of two solders’ IMC layer follows a liner relation with square root of aging time.The growth activation energy of IMC of SAC305/Ni-P and the SACBN/Ni-P is 65.18kJ/ mol and 58.36kJ/mol

respectively.