Abstract: The interface interactions of cyclohexenyl-POSS on the(100),(110) and(001) planes of the lead free solder joints β-Sn,and on the surface of the Sn-Ag-Cu alloy were performed via the molecular dynamics(MD) simulations.The cohesive energies were also obtained.The results show that the cyclohexenyl-POSS can be easily absorbed on the main crystal planes of β-Sn.But the cohesive energy on(110) plane is the lowest,thus the cyclohexenyl-POSS will be absorbed on the(110) plane most likely.Adding the silver(Ag) and the copper(Cu) into β-Sn to form the Sn-Ag-Cu alloy raises the cohesive energies of cyclohexenyl-POSS on the alloy surfaces and generate the unfavorable absorbing effect.But the cyclohexenyl-POSS can also be easily absorbed on the surfaces.Moreover,the solubility parameter of the cyclohexenyl-POSS was computed from the MD simulations.