Abstract: Nanoindentation experiments were carried out on (Cu, Ni)₆Sn₅, Cu₆Sn₅ and Cu₃Sn IMCs in BGA soldered joints. The influence of loading velocity on the mechanical behavior of intermetallic compounds was investigated. The Young's modulus and nanoindentation hardness of (Cu, Ni)₆Sn₅, Cu₆Sn₅ and Cu₃Sn IMCs were obtained from load-depth curves with Oliver-Pharr method. The results indicate that serrated rheological effect was related to the load rate. All of three kinds of IMC, including Cu₆Sn₅, Cu₃Sn and (Cu, Ni)₆Sn₅, showed serrated rheological effect with different degrees when the loading rate was low. However, the serrated rheological effect was not obvious for Cu₃Sn and (Cu, Ni)₆Sn₅, except for Cu₆Sn₅, when the loading rate increased. The Young's modulus of (Cu, Ni)₆Sn₅, Cu₆Sn₅ and Cu₃Sn IMCs were 126 GPa, 118 and 135 GPa, respectively.The nanoindentation hardness of (Cu, Ni)₆Sn₅, Cu₆Sn₅ and Cu₃Sn IMCs were 6.5, 6.3 and 5.8 GPa, respectively. The Young's modulus and nanoindentation hardness of (Cu, Ni)₆Sn₅were higher than those of Cu₆Sn₅.