Lead-free　solders　with　excellent　material　properties　and　low　cost　are　essential　for　the　electronics　industry.　It　has　been　proved　that　mechanical　properties　of　SnAgCu　alloys　can　be　remarkably　improved　with　a　minute　addition　of　rare　earth　(RE)　elements.　For　comparison　and　optimization,　three　valuable　solder　candidates,　Sn3.8Ag0.7Cu0.05RE,　Sn3Ag0.5Cu0.05RE,　and　Sn2.9Ag1.2Cu0.05RE,　were　chosen　due　to　the　excellent　properties　of　their　own　SnAgCu　basic　alloys.　Wetting　properties,　melting　temperature,　bulk　tensile　properties,　and　joint　tensile　and　shear　properties　were　investigated.　In　addition,　the　microstructures　of　solder　joints　were　observed　and　the　effects　of　microstructure　on　mechanical　properties　were　analyzed.　Experimental　results　indicated　that　the　tensile　and　shear　strengths　of　solder　joints　were　decreased　from　Sn3.8Ag0.7Cu0.05RE,　Sn2.9Ag1.2Cu0.05RE,　to　Sn3Ag0.5Cu0.05RE,　in　order.　Such　difference　in　mechanical　properties　could　be　attributed　to　the　influence　of　slightly　coarse　or　strong　Cu(6)Sn(5)　scallops　in　the　reaction　layer　as　well　as　superior　eutectic　network　and　large　volume　percentage　of　large　primary　intermetallic　compounds　(IMCs)　inside　the　solder　joints.　It　is　also　suggested　that　the　size　and　volume　percentage　of　large　primary　IMCs　inside　the　solder　be　controlled.　In　addition,　serration　morphology　was　observed　at　the　edge　of　large　primary　and　eutectic　IMCs　in　the　three　solder　joints,　which　could　be　related　to　the　content　of　Ag,　Cu,　and　RE.　The　serration　morphology　was　proved　to　be　beneficial　to　mechanical　properties　theoretically.　Furthermore,　the　three　alloys　investigated　possessed　similar　wetting　properties,　melting　temperatures,　and　bulk　tensile　properties.