First of all, there should be a high-voltage source, probe, generally at 125 degrees when the test is rarely tested at room temperature! Set the oven temperature to 125 degrees IGBT module C-E short to the oven! About an hour or so module temperature reaches 125 degrees, the upper bridge test: the probe (+) connected to 3 probe (-) connected to 1 lower bridge test: probe (+) 1 probe (-) connected to 2 Note: Due to the high temperature of the probe line is best to use high-temperature adhesive (high-temperature adhesive is similar to a transparent adhesive, into a dark yellow color) to protect it! Each 5 copies of the clock plus 1200V voltage, know that the leakage current does not change indicates stability, generally about an hour of stability less than 5mA can be judged qualified.
PN junction in the cut-off flow of a very small current. In the D-S is not in forward bias, G-S reverse bias, the conductive channel open, D to S before the current will flow. But in reality, due to the presence of free electrons, the attachment of free electrons to SIO and N+, resulting in a leakage current in D-S.