The　grain　orientations　of　a　Pb-free　ball　grid　arrays　solder　joint　after　thermomechanical　fatigue　(TMF)　were　characterized　quantitatively　using　electron　backscattered　diffraction.　Due　to　subgrain　rotation,　the　small　recrystallized　grains　evolved　from　the　reflowed　orientations　appeared　in　a　Pb-free　solder　joint　subjected　to　thermomechanical　stress.　Also,　these　recrystallized　grains　rotated　under　electron　current　stress,　indicating　that　the　tin　orientations　of　the　Pb-free　solder　joints　can　significantly　affect　the　response　of　the　solder　joints　to　service　conditions　such　as　TMF　and　electromigration.　Meanwhile,　two　types　of　double　twinning　of　tin　in　solder　joints　were　observed　in　Pb-free　solder　joints.　The　change　in　orientation　between　the　two　groups　of　double　twined　orientations　was　in　the　range　of　80A　degrees-90A　degrees　(79.1A　degrees,　82.9A　degrees　and　86.5A　degrees　corresponding　with　57.2A　degrees　and　62.8A　degrees).　Four　orientations　of　tin　grains,　having　the　same　twin　grain　with　a　[100]　or　[010]　direction　were　observed　in　one　of　the　systems,　while　the　other　one　presented　with　two　groups　of　tricrystals　perpendicular　to　each　other.