Power semiconductor module

A power semiconductor module, comprising:

• a metal base plate;
• an insulating substrate arranged on the metal base plate and provided with an electrode;
• a semiconductor element arranged on the insulating substrate;
• a case arranged on the metal base plate so as to surround the insulating substrate and the semiconductor element;
• and
• a potting material filled into a space defined by the metal base plate and the case so as to seal the insulating substrate and the semiconductor element,
• the potting material containing:
• a silicone gel;
• and
• a conductivity-imparting agent added to the silicone gel and contains a silicon atom and an ionic group,
• wherein the potting material satisfies, under a state in which an evaluation substrate that is obtained by forming on a silicon nitride substrate a comb-shaped opposing electrode pattern having comb electrodes arranged alternately at an interval of 1 mm is sealed by the potting material, a condition that an amount of leakage current generated at a comb-electrode boundary is 1.5×10−8 A or less and 4.2×10−10 A or more, which value is measured after 300 seconds from application of a DC voltage of 1 kV between the comb electrodes of the comb-shaped opposing electrode pattern.