Small current unclamped inductive switching (UIS) to detect fabrication defect for mass-production phase IGBT

In Unclamped Inductive Switching (UIS) with a small capacitance, the L load current flows into the breakdown point selectively. V_ava, which is a peak voltage during this UIS turn-off, is also widely changed by the ON state forward voltage drop V_on. Along this V_on index, two types of failure modes are detected. One is the weak point of the design and the other is the fabrication defect. Our proposing UIS is one of the most effective approaches to detect the fabrication defects instead of the huge current class module test like an SCSOA. And also V_on is one of the major controlling factors of UIS capability other than the index of power loss.