473 / 2022-03-16 00:10:30

Effect of Silane Coupling Agent Modified Nano-AlN on Electrical and Aging Properties of Silicone Elastomer for High-temperature and High-voltage SiC Electronic Packaging

Silicone elastomer, nanocomposites, electrical properties, thermal aging, quantum chemical calculations

The pure silicone elastomer and its silane coupling agent modified nanocomposites were thermally aged for 500 h under 250 °C, and the samples before and after aging were subjected to SEM cross-section characterization, thermogravimetric analysis (TGA), DC conductivity and depolarization current testing, space charge measurement, dielectric spectroscopy, DC breakdown experiment and quantum chemical calculations (QCC). The interface state variation between the silicone elastomer matrix and the nano-AlN during the thermal aging process was analyzed. The results show that the pure silicone elastomer produces a large number of chain scission and internal micropores after thermal aging due to thermal decomposition, increasing the shallow trap density. Before thermal aging, an interfacial gap exists between the silicone elastomer matrix and nano-AlN, decreasing the shallow trap depth. The interface state before and after aging has an obvious effect on the thermal stability and electrical properties of the silicone elastomer nanocomposites. Chemical bonds and hydrogen bonds are formed between the silicone elastomer matrix and the nano-AlN after thermal aging, which not only improves thermal decomposition temperature but also increases deep traps depth and density. Compared with the aged pure silicone elastomer, the aged nanocomposites have lower DC conductivity, less space charge accumulation, and higher DC breakdown strength, especially, 3 wt% nanocomposite has the best thermal decomposition inhibition effect.