In　3D　through-silicon-via　(TSV)　interposer　packages,　there　are　many　micro　bumps　and　micro　solder　balls,　the　size　of　which　might　be　different　by　1000　times.　This　multi-scale　structure　brings　difficulties　in　building　the　finite　element　model.　Homogenization　method　was　adopted　to　avoid　these　difficulties　in　this　paper.　The　micro　bump/underfill　layer　between　the　chip　and　the　TSV　interposer,　and　the　micro　solder　ball/underfill　layer　between　the　interposer　and　the　substrate　were　replaced　by　homogenous　material　layers.　Four　different　homogenization　schemes　were　proposed　to　compute　the　thermal　fatigue　life　of　the　board　level　solder　joints,　and　the　results　were　compared.　It　is　suggested　that　the　micro　bump/underfill　layer　between　the　chip　and　the　interposers,　and　the　micro　solder　ball/underfill　layer　between　the　interposer　and　the　substrate　can　be　replaced　by　their　own　underfill　material　layer　in　a　finite　element　analysis　of　the　thermal　fatigue　life　of　board　level　solder　joints.　©,　2015,　Tsinghua　University.　All　right　reserved.