Thermal Behavior of Paralleling IGBTS

Using multiple smaller chips instead of one larger chip improves the thermal behavior, as they doesn`t heat as quickly as a larger one, they tend to devides the heating properties well, This is due to the fact that not only the chip itself, but also a certain area around the chip, will participate in the transfer of heat from the chip to the heatsink. Parallelling systems have improved thermal spreading when using two small chips instead of one large, with in equal total area in both cases.

This case can also be seen when comparing the thermal resistance of the 100 A IGBT in the P569-F module with the 35 A IGBT in the P700-F module. The thermal resistance junction to heatsink for the 100 A the device is 0,57 K/W. The resistance for the single 35 A IGBT is 1,29 K/W, resulting in an  resistance of 0,43 K/W, when 3 of them are used in parallel. This provides an improvement of about 25 % in thermal performance,one point for these kind of system, that left behind the more traditional one-module igbt old system, this also compensates for some if not all of the de-rating required due to the non-ideal current sharing.