Several　types　of　surface　finishes　have　been　applied　on　Cu　substrates　in　an　effort　to　facilitate　bonding　and　improve　the　reliability　of　lead-free　solder　joints.　In　the　current　research,　the　effects　of　printed　circuit　board　surface　finishes　on　the　reliability　of　the　solder　joints　were　investigated　by　examining　the　morphology　and　growth　behavior　of　the　intermetallic　compounds　(IMCs)　between　Sn-based　solders　and　different　surface　finishes　on　Cu.　Three　types　of　Cu　substrates　with　different　surface　finishes　were　fabricated　in　this　study:　organic　solderability　preservative　(OSP)/Cu,　Ni/Cu,　and　electroless　nickel　immersion　gold　(ENIG)/Cu.　Sn-3.5Ag　and　Sn-3.0Ag-0.5Cu　were　used　as　the　solders.　In　the　experiment,　the　solder　joint　specimens　were　aged　isothermally　at　150A　degrees　C　for　up　to　1000　h.　Experimental　results　revealed　that　the　OSP　surface　finish　promoted　the　interdiffusion　between　Cu　and　Sn　during　soldering.　The　composition　and　morphology　of　the　IMC　layer　at　the　solder/Ni/Cu　interface　were　sensitive　to　the　Cu　concentration　in　the　solder.　Meanwhile,　the　solder　joints　with　different　morphological　features　of　the　IMCs　exhibited　significant　differences　in　shear　strengths.　The　Au-containing　ENIG　surface　finish　affected　the　shear　strength　of　the　solder　joint　significantly　at　the　initial　stage　of　isothermal　aging.