High-temperature failure mechanism and lifetime assessment of silicone gel package insulation for high-power electronic devices based on pyrolysis kinetics

High temperature tends to be one principal failure cause of silicone gel package insulation in high-power electronic devices, even leading to equipment damage under severe conditions. To clarify the aging characteristics and failure mechanism of silicone gel package insulation of high-power IGBT devices under the high-temperature scenario, this paper carries out experiments on silicone gel material samples by accelerated thermal aging procedures at 200 ℃. The experimental results show that temperature has a significant effect on the physicochemical properties of silicone gel. Further, molecular dynamics simulations are conducted to verify the high-temperature degradation characteristics of the gel. Finding the main cause of silicone gel package insulation failure under high-temperature is the random degradation of the silicone backbone into small molecule cyclosiloxanes. Finally, the Lifetime assessment model was established based on the pyrolysis kinetics and insulation failure mechanism. The unaged silicone gel's pyrolysis activation energy and insulation failure temperature were measured at 125.8 kJ/mol and 453°C, respectively. The evaluation results show that the package insulation life decreases by about 60% for every 10°C increase in temperature. The above achievement of this study presents a theoretical and methodological basis for reliable assessment of the insulation status of silicone gel package insulation for high-power electronic devices under high-temperature.