High Reliability SiC Power Switch Module Packaging

Wide bandgap power devices from materials such as SiC inherently operate at much higher temperatures than silicon devices. Higher critical fields and electron saturation velocities enable devices to have lower electrical on-resistance, higher thermal conductivities and operate at higher switching frequencies. To utilize these advantages, the need exists to develop suitable switch-module component technologies, which possess required electrical and mechanical characteristics. The key focus of this research is on demonstration of suitable base-plates / heat sink technology, high dielectric strength encapsulates, robust interconnect metallurgy and techniques, and die attach metallurgy suitable for reliable module operation from -40ºC to 250ºC. The wide-range temperature cycling places stringent requirements on creating manageable thermal gradients within materials, prevention of material degradation from metallurgical incompatibilities, and assuring robust interconnect reliability. Target power module terminal ratings for technology are 1800 volts, and 100 amps continuous conduction in current applications. In addition, suitable module configurations utilize these robust technologies to minimize parasitic electrical impedances to enable switching and transient frequencies beyond 250 kHz. The technology addresses heat transport and thermal impedance characteristics to minimize device junction temperatures for >250ºC heatsink excursion temperatures.