The　Sn-Pb　solder　is　widely　used　in　the　electronics　industry.　With　the　development　of　surface　mount　technology　and　miniaturization　of　elements,　mechanical　properties　of　the　solder　are　critical.　Creep　resistance　and　size　stability　of　soldered　joints　are　important　for　optical　electronics.　In　the　present　work,　Cu　particles　with　a　size　of　about　8　mum　were　added　to　the　eutectic　63Sn-37Pb　solder　to　improve　the　creep　property　of　the　soldering　alloy.　The　contents　of　the　Cu　particles　are　5　vol.%　and　10　vol.%　separately.　The　solder　matrix　is　63Sn37Pb　particles　with　a　normal　size　of　43　mum.　The　composite　solder　pastes　are　manufactured　from　a　mixture　of　these　particles　with　no-clean　flux.　Under　reflow　soldering,　the　metal　particles　were　uniformly　dispersed　in　the　Sn-Pb　alloy,　and　very　thin　intermetallic　compounds　were　formed　between　the　particles　and　matrix.　To　simulate　practical　soldering　of　printed　circuit　boards,　a　specially　designed　mini　specimen　with　lap　joint　is　used　for　the　creep-rupture　test.　For　the　condition　of　ambient　temperature,　the　creep-rupture　lifetime　of　the　soldered　joint　can　be　increased　by　one　order　quantitatively　using　the　composite　solder　compared　to　the　63Sn37Pb　eutectic　solder.　Other　mechanical　properties　are　measured　also.　In　addition,　the　wetting　property　of　the　enhanced　solder　is　good　through　the　wettability　test.