Development　of　lead-free　solders　with　low　melting　temperature　is　important　for　substitution　of　Pb-based　solders　to　reduce　direct　risks　to　human　health　and　the　environment.　In　the　present　work,　Sn-Bi-In　solders　were　studied　for　different　ratios　of　Bi　and　Sn　to　obtain　solders　with　low　melting　temperature.　The　microstructure,　thermal　properties,　wettability,　mechanical　properties,　and　reliability　of　joints　with　Cu　have　been　investigated.　The　results　show　that　the　microstructures　of　the　Sn-Bi-In　solders　were　composed　of　beta-Sn,　Bi,　and　InBi　phases.　The　intermetallic　compound　(IMC)　layer　was　mainly　composed　of　Cu6Sn5,　and　its　thickness　increased　slightly　as　the　Bi　content　was　increased.　The　melting　temperature　of　the　solders　was　around　100A　degrees　C　to　104A　degrees　C.　However,　when　the　Sn　content　exceeded　50　wt.%,　the　melting　range　became　larger　and　the　wettability　became　worse.　The　tensile　strength　of　the　solder　alloys　and　solder　joints　declined　with　increasing　Bi　content.　Two　fracture　modes　(IMC　layer　fracture　and　solder/IMC　mixed　fracture)　were　found　in　solder　joints.　The　fracture　mechanism　of　solder　joints　was　brittle　fracture.　In　addition,　cleavage　steps　on　the　fracture　surface　and　coarse　grains　in　the　fracture　structure　were　comparatively　apparent　for　higher　Bi　content,　resulting　in　decreased　elongation　for　both　solder　alloys　and　solder　joints.