Rare　earth　elements　are　recognized　as　the　＂vitamin＂　of　metals,　and　trace　amount　of　rare　earth　Ce　can　effectively　improve　the　comprehensive　properties　of　the　solder　alloy.　However,　rapid　tin　whisker　growth　has　been　found　when　excessive　amount　of　rare　earth　were　doped　in　the　solder　alloys.　The　results　indicated　that　the　rare　earth-phase　will　be　oxidized　and　induce　volume　expansion　when　Sn　3.8Ag0.7Cu1.0Ce　solder　was　exposed　in　air,　and　the　constraint　action　of　the　solder　matrix　on　the　volume　expansion　of　the　oxidized　rare　earth-phase　will　result　in　a　compressive　stress　that　will　accelerate　the　growth　of　tin　whiskers.