Thermal design and measurements of IGBT power modules: transient and steady state

The spatial temperature distributions on IGBT devices in 6-pack power modules have been measured during both transient and steady-states using ultra high speed infrared microscopy. Power modules examined included a commercial 6-pack module and a miniaturized inverter. The modules were constructed using both Al₂O₃ and AlN direct bond copper (DBC) substrates and an insulated metal substrate (IMS). The effects of IGBT bonding pad design and layout, bond wire arrangement and module curvature on the temperature distribution were measured and analyzed. Thermal performances of all the modules were characterized by the junction-to-case, case-to-sink and sink-to-ambient thermal resistance. The trade-offs between AlN, Al₂O₃ , and IMS substrates and the replacement of conventional solder with a conductive adhesive are discussed from thermal, reliability and cost viewpoints