18 AEROSPACE www.microchip.com Issue 3 2023 Power Electronics Europe www.power-mag.com (see Figure 4), do not show degradation at solder joint or substrate level capable of reducing the device performances. Vibration and shocks. After securing the power modules to a plate mounted on a vibration shaker, they were tested in three axes for vibration and shocks. Chopper mode bias (CMB). The purpose of this test is to verify the robustness of the device when it is operating in chopper mode at high temperature. Test conditions were the following: VGS = -5V, switching frequency = 20kHz, duty cycle = 0.5, T = 150˚C, test duration = 1,000 hours. Figure 5 shows the CMB test plot after 1,000 hours (200V/div). Partial discharge. This test aims to verify the insulation health of the DUT and is important for SiC power modules, which operate at high voltages and high dV/dt rates. Thermal simulations and measurements. Thermal simulation determines the DUT thermal resistance and thermal impedance values, while thermal measurement confirms the thermal resistance junction-toheatsink calculated during the simulation. The switch under test, previously prepared with a modified package (Figure 6) was turned on, and a constant-current generator produced a junction temperature increase to calculate the thermal resistance. The results of the measurement confirmed the thermal simulations. All tests were performed by Microchip. The company says passing these tests demonstrate reliability and prove this technology is qualified and suitable to serve ever more challenging aircraft applications. Figure 4: X-ray analysis before and after 1,000 temperature cycles Figure 5: CMB test plot Figure 6: Thermal measurement setup
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