Low　cycle　mechanical　fatigue　tests　on　96.5Sn-3Ag-0.5Cu　lead-free　solder　joints　were　carried　out　using　a　micro-uniaxial　fatigue　testing　system　at　25　degrees　C　with　different　frequencies　(1　similar　to　10　Hz)　and　a　wide　range　of　strain　(2%similar　to　8%).　The　results　show　that　the　low　cycle　fatigue　(LCF)　life　of　the　solder　joint　follows　the　Coffin-Manson　equation　in　different　strain　ranges.　Frequency-modified　Coffin-Manson　equation　can　describe　the　frequency　effect　on　the　fatigue　life　of　lead-free　solder　joints.　The　analysis　of　failure　process　show　that　the　fatigue　cracks　initiate　at　the　interfaces　between　the　solder　and　inter-metallic　compound　(MC)　around　the　edge　of　the　joints,　and　then　propagate　within　the　solder　along　the　solder/MC　interfaces　proximately.　Fracture　morphologies　of　solder　joints　under　different　frequencies　mainly　consist　of　an　initiated　region,　a　propagation　region　and　a　final　fracture　region.　The　fracture　mechanism　of　the　final　fracture　region　transforms　from　inter-granular　fracture　to　trans-granular　fracture　with　increasing　of　frequency.