It　is　well　known,　reliability　and　workability　are　the　more　important　issues　in　the　field　of　chip　size　package　(CSP).　Creep　and　fatigue　behaviors　are　the　main　loads　of　the　solder　joints,　the　reliability　of　which　should　take　account　of　those　two　main　loads.　Based　on　the　theory　of　continuum　damage　mechanics　(CDM),　this　paper　focuses　on　damage　evolution　of　interaction　between　the　fatigue　and　creep.　A　new　damage　model　of　fatigue-creep　interaction　has　been　developed.　And　the　new　fatigue-creep　interaction　damage　model　in　this　paper　does　not　require　the　simple　fatigue　model　and　simple　creep　model.　©　2008　IEEE.