Material Advancements in High-Power Module Packaging for Traction Inverters in Electric Vehicles

Power modules are core components of inverters and converters in solar power plants, data center power supplies and in electric vehicles. Their packaging technology has a critical impact on system performance, reliability and lifetime. Due to their superior material properties, wide bandgap (WBG) semiconductors like Silicon Carbide (SiC) and Gallium Nitride (GaN) enable the application of power electronics at higher temperature operation, higher frequencies, and higher efficiencies as compared to silicon (Si).

Conventional single sided cooled frame-type power modules have been one of the most common package structures for automotive applications. However, this design constrains the performance of both traditional IGBT and future SiC power modules due to parasitic inductance and heat dissipation challenges. Recent advancements in power module packaging technologies—including concept, material, and process innovations—have emerged in response to increased performance expectations for power semiconductors.

We provide an overview of cutting-edge automotive power module packaging materials and processes, emphasizing their application in traction inverters for electric vehicles. We examine the driving factors behind modern packaging and interconnect technology development, highlighting the transition from frame-type to compact plastic-molded power modules. Molded modules offer greater flexibility and are often custom designed for specific inverter environments. Currently, the highest thermal performance is achieved with thin double-sided cooled power modules.

Recent advancements in robust topside interconnection technologies for WBG semiconductor power devices are crucial to meeting the demanding lifetime requirements of new high-end electric vehicles. Nexperia has introduced the copper clip interconnect technology for robust high-power cascode GaN devices. For die attach, Cu sintering has a high potential to replace state-of-the-art Ag sintering because of process simplification and material cost saving.

The latest trend in power module packaging involves embedding power semiconductor devices into printed circuit boards (PCBs). Significant technical progress has been made in this area, where integrating semiconductor dies into the circuit board significantly reduces converter size. This integration shortens current loops, resulting in lower interconnection resistances and parasitic inductances, which in turn enhances system-level efficiency by reducing conduction and switching losses.