To　investigate　the　effect　of　the　epoxy　resin　shell　on　the　thermal　stability　of　Sn-Bi　solder　joints,　the　temperature　range　of　130　-170　℃　was　set　and　thermal　cycling　tests　were　carried　out　on　solder　joints　formed　by　self-made　epoxy-based　Sn-Bi　solder　paste　and　commercial　Sn-Bi　solder　paste　(without　curable　resin).　Results　show　that　after　1　000　thermal　cycles,　the　epoxy　resin　shell　on　the　surface　of　the　solder　joints　formed　by　the　epoxy-based　Sn-Bi　paste　remains　intact　and　the　thickness　of　the　intermetallic　compound　between　the　solder　joint　and　the　copper　substrate　is　also　significantly　lower　than　that　of　the　commercial　Sn-Bi　solder　pastes.　The　electrical　conductivity　of　the　solder　joint　formed　by　the　epoxy-based　Sn-Bi　paste　decreases　from　1.　90　×106　S/　m　to　7.　96　×105　S/　m　after　1　000　thermal　cycles,　and　the　shear　strength　decreases　from　145.　7　MPa　to　123.　7　MPa.　However,　the　electrical　conductivity　of　the　solder　joint　formed　by　the　commercial　Sn-Bi　paste　decreases　from　1.　94　×106　S/　m　to　4.　95　×105　S/　m,　and　the　shear　strength　decreases　from　116.　1　MPa　to　97.　3　MPa.　Therefore,　compared　with　commercial　Sn-Bi　solder　paste,　the　epoxy　resin　shell　on　the　surface　of　the　solder　joint　formed　by　epoxy-based　Sn-Bi　solder　paste　effectively　improves　the　shear　strength　and　thermal　stability　of　the　solder　joint,　and　to　some　extent　hinders　the　growth　of　intermetallic　compounds.　©　2025　Beijing　University　of　Technology.　All　rights　reserved.