Effects of spherical Al2O3 grades on crack initiation of thermal conductive silicone pads under high-temperature aging

In this paper, the rule and mechanisms of crack initiation and propagation in the aging process of thermal conductive silicone pads (TCSP) were investigated by designing Al2O3 particle grading schemes with different particle sizes and mass ratios. Scanning electron microscope and energy dispersive spectrometer analysis showed that TCSP prepared with Al2O3 particles of various sizes according to the gradation ratio had the best anti-aging effect at high temperatures. At this time, the aging was mainly due to the aging degradation of the polymer matrix; When the proportion of small-size Al2O3 particles increases, aggregates and pore defects appear in TCSP. At this time, the main reason for its aging is that the high-temperature expansion of gas in pore defects accelerates the aging degradation of the polymer matrix; When the proportion of small-sized Al2O3 particles decreases, a large number of holes appear in TCSP and the coverage rate of the polymer matrix on Al2O3 particles decreases. The main reason for the high-temperature aging crack is that the gas between the holes expands at high temperature, resulting in the rapid extension of the crack and the polymer matrixes falling.