Electric　field　stress　concentration　is　one　of　the　causes　of　partial　discharge　(PD)　in　power　modules,　which　threatens　the　power　modules＇　safe　operation.　Herein,　this　article　investigates　the　influences　of　temperature　(from　150　to　250°C　)　and　operation　duration　on　the　maximum　electric　field　stress　at　the　triple　point　(silicone　elastomers,　ceramic,　and　copper).　It　reveals　that　the　maximum　electric　field　stress　rises　with　the　increase　in　temperature,　while　the　maximum　electric　field　first　increases　but　then　decreases　along　the　operation　duration,　especially　under　low　temperature.　Both　the　influences　of　temperature　and　the　operation　duration　are　related　to　the　permittivity　(dominated　by　the　relaxation　of　Si-O　bonds),　low-frequency　dispersion　(LFD)　phenomenon,　and　dc　conductivities　of　silicone　elastomers,　which　can　be　manipulated　to　suppress　electric　field　stress　concentration.　This　article　provides　a　method　to　accurately　calculate　the　electric　field.　The　results　are　also　critical　to　evaluation　and　improvement　of　power　modules＇　insulation.　©　2013　IEEE.