AlN填充有机灌封硅橡胶导热性能的数值模拟

Numerical simulation of the thermal property of AlN filled silicone encapsulant

通过数值技术及实验手段研究了含有球形氮化铝(AlN)导热填料的有机灌封硅橡胶的导热性能。采用随机序列吸附(RSA)方法,建立了AlN增强有机灌封硅橡胶的三维有限元模型,该模型可以生成颗粒位置随机分布、颗粒直径任意调整的代表体积单元,能够得到单一粒径和多粒径的模型。制备了半径3μm AlN增强硅橡胶的复合材料,并测试了不同填充量下体系的导热系数。对比有限元方法得到的导热系数预测值与实验测试结果,证明该模型能够较精确地模拟球形填料增强的复合材料。模拟结果显示:灌封胶的导热系数随着AlN含量的增加而增大,并且质量分数大于50%时增大的幅度越来越大;填料粒径呈正态分布时,能够在硅橡胶基体中有效堆积而提高填充量;两种粒径比例不同时,导热系数也不同。

The thermal property of AlN filled silicone encapsulant was investigated through experimental method and numerical simulation.A 3D finite element model of AlN filled silicone encapsulant was built by random sequential adsorption（RSA） method.This model can generate representative volume element of random particle location and different particle diameters.The single particle size and multiple particle sizes models can be established.The AlN particles in 3μm filled silicone encapsulant composite was prepared and the thermal conductivity was tested at different filling volume.The model was verified to be accurate by comparing the predicted and the practical thermal conductivity.The simulation results show that thermal conductivity of the silicone encapsulant increases with the filler mass fraction,and the thermal conductivity increases rapidly after the filler mass fraction being higher than 50%.When the AlN particles with normal distribution pack effectively,the filling volume is increased.The thermal conductivity is different when the composite is filled with different mass ratio of two different particles.