A　3-D　finite　element　model　of　board　level　BGA　package　was　built　and　the　Input-G　method　was　used　to　analyze　dynamic　solder　joint　stress　in　the　package　during　drop/impact.　Boundary　condition,　bolt　effects　of　the　test　board　and　peeling　stress　mechanism　were　emphasized　in　current　investigation.　Dynamic　responses　of　solder　joint　in　frequency　domain　and　time　domain　were　analyzed　to　find　main　mechanism　of　stress　generation.　The　results　show　that　bolt　constraints　have　a　significant　influence　on　the　dynamic　stress　in　solder　joints.　The　bolt　constraints　must　be　treated　as　zero　horizontal　displacement　in　the　area　the　bolt　acted　in　the　numerical　model.　The　stress　in　the　solder　joint　reaches　its　peak　at　0.4ms　and　the　maximum　peeling　stress　is　located　at　the　most　outer　corner　of　the　package.　The　peeling　stress　is　dominated　by　the　deflection　of　the　PCB　board.　Due　to　effect　of　the　5th　vibrating　mode,　the　stress-time　curve　of　the　solder　joints　is　not　smooth.　©2007　IEEE.