Abstract: The growth rate of interfacial intermetallic compounds (IMC) is an important factor to influence the reliability of a solder joint. In this paper, the effects of joint size, temperature and pre-plated nickel coating on the growth rate of interfacial IMC of SAC305/Cu micro joint were studied. The results showed that the growth rate of the interfacial IMC increases with the square root of aging time rising under the conditions: solder size 200, 300, 400, 500 μm, and aging temperature 100, 130, 160 ℃. Along with the joint size getting larger, the interfacial IMC thickness is thinner with smaller IMC growth rate. The growth rate of interfacial IMC increases with the temperature rising. The plated nickel coating suppresses the growth rate of interfacial IMC obviously, i.e. reducing the growth rate of IMC.