This　study　quantifies　the　correlations　between　crack　evolution　and　electrical　performance　degradation　of　the　Al　metallization　in　insulated　gate　bipolar　transistor　(IGBT)　modules.　The　resistance　of　the　Al　metallization　under　different　power　cycling　times　was　measured　by　the　four-point　probe　method.　The　cracks　that　occur　in　the　Al　metallization　were　investigated　by　measuring　crack　geometric　parameters,　e.g.,　shape,　geometric　size　and　density.　Simplified　analytical　models　containing　different　crack　geometric　parameters　were　established　by　the　finite　element　method　(FEM).　The　influences　of　crack　evolution　on　the　resistance　and　current　density　of　the　Al　metallization　were　quantitatively　analyzed.　The　results　indicate　that　the　crack　depth　has　the　largest　effect　on　the　Al　metallization　resistance　compared　with　the　crack　length　and　width.　At　the　later　stage　of　power　cycling,　increasing　the　crack　depth　plays　a　critical　role　in　metallization　resistance　degradation.　In　addition,　cracks　affect　the　current　flow　direction　and　the　maximum　current　density　in　the　Al　metallization.　With　increasing　crack　depth　and　length,　the　maximum　current　density　in　the　crack　vicinity　increases　continuously.　However,　increasing　the　crack　width　reduces　the　maximum　current　density.