Abstract

High-power modules incorporating insulated gate bipolar transistors (IGBT) include a thick layer of dielectric insulating gel to prevent arcing. Chemical methods currently used to remove the gel are slow, taking up to 24 hours, while generating as much as a half-gallon of waste. High-pressure wet jets have also been used, but they cause significant damage to wire bonds. In this paper, we present a fast and efficient process for removing insulating gel from high-power modules. The method uses a CO2 laser to selectively open windows in the gel that are then filled with a few drops of solvent followed by a DI water rinse. The entire process takes less than an hour to prepare samples for inspection and analysis, while generating just 200ml of waste.

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