Two　copper　substrates　electroplated　with　Sn,　both　consisted　of　Cu/Sn　+　Sn/Cu　structures,　but　they　were　bonded　over　different　times　in　order　to　investigate　the　interfacial　reaction.　The　growth　morphologies　of　Cu6Sn5　and　Cu3Sn　were　analysed,　respectively.　The　growth　mechanisms　for　Cu6Sn5　and　Cu3Sn　were　investigated.　The　results　show　that　the　growth　of　Cu6Sn5　is　primarily　controlled　by　grain　boundary-diffusion.　However,　the　growth　Cu3Sn　is　controlled　by　the　reaction　of　Cu-Cu6Sn5　at　the　beginning　of　the　reaction,　and　then　controlled　by　volume-diffusion　as　the　thickness　of　the　Cu3Sn　layer　increases.