The　strain　rate　dependent　Johnson-Cook　material　model　and　the　rate　independent　elastic-plastic　model　of　lead-free　solders　were　used　to　investigate　influence　of　strain　rate　effect　on　the　mechanical　behavior　of　solder　joints　under　drop　impact　loadings.　Failure　of　the　solder　joints　was　predicted　and　the　results　were　compared　with　the　experimental　observations.　The　strain　rate　effect　of　lead-free　solders　has　no　influence　on　the　deflection　of　the　PCB　during　the　drop　impact　but　has　significant　influence　on　the　stress　and　strain　in　solder　joints.　The　rate　independent　elastic-plastic　solder　material　model　always　underestimates　the　stress　and　overestimates　the　strain　of　the　solder　joint.　The　material　model　that　takes　the　strain　rate　effect　into　account　can　predict　more　realistic　behavior　of　the　solder　joints.　©2009　IEEE.