The　effect　of　trace　amounts　of　rare　earth　additions　on　the　microstructure　and　properties　were　studied　for　the　Sn-58Bi　and　Sn-58Bi-Ag　solder　alloys.　At　the　same　time,　the　intermetallic　compounds　(IMCs)　in　the　solder　alloys　and　intermetallic　layer　(IML)　thickness　at　the　solder/Cu　substrate　interface　were　investigated,　both　as-reflowed　and　after　high-temperature　aging.　The　results　indicate　that　adding　trace　amounts　of　rare　earth　(RE)　elements　has　little　influence　on　the　melting　temperature　and　microhardness　of　the　solders　investigated,　but　adding　RE　elements　improves　the　wettability　and　shear　strength　of　the　Sn-58Bi　and　Sn-58Bi-Ag　solder　alloys.　In　addition,　it　was　found　that　the　addition　of　RE　elements　not　only　refines　the　microstructure　and　size　of　the　IMC　particles,　but　also　decreases　the　IML　thickness　and　shear　strength　of　the　Sn-58Bi　solder　joint　after　high-temperature　aging.　Adding　trace　amounts　of　RE　elements　is　superior　to　adding　trace　amounts　of　Ag　for　improving　the　properties　of　the　Sn-58Bi　solder.　The　reason　may　be　related　to　the　modification　of　the　microstructure　of　the　solder　alloys　due　to　the　addition　of　trace　amounts　of　RE　elements.