The　samples　were　soldered　using　copper　pillars　and　Sn-3.0Ag-0.5Cu　solder　paste　with　a　typical　reflow　profile　about　peak　time　of　245°C.　In　order　to　observe　the　microstructure　and　crystal　orientations,　the　sample　is　grinded　and　polished　to　be　characterized　by　scanning　electron　microscope　(SEM)　and　electron　backscattered　diffraction　(EBSD).　By　analyzing　the　microstructure　and　crystal　orientation,　the　number　of　grains　contained　in　the　sample　and　grain　orientation　is　obtained.　Next,　in　order　to　study　the　relationship　between　deformation　and　crystal　orientation,　the　sample　was　subjected　to　uniaxial　tensile　test.　The　following　results　were　obtained　by　the　experiment:　1)　In　the　process　of　deformation,　the　slip　system　which　is　activated　is　closely　correlated　to　the　grain　orientation;　2)　There　may　be　several　slip　systems　that　were　activated　during　deformation,　though　the　solder　joint　is　the　single　crystal　structure.　©　2017　IEEE.