考虑残余应力的高低温循环下灌封模块开裂机理分析及试验验证

Cracking mechanism analysis and experimental verification of encapsulated module under high low temperature cycle considering residual stress

针对改性环氧树脂灌封模块在高低温循环下因界面失效而导致的开裂破坏问题,开展了数值模拟与试验研究。采用钻孔法测试环氧树脂灌封固化的残余应力,重构灌封模块内的残余应力场;试验测试高低温环境下改性环氧树脂等灌封模块组件材料的力热特性参数,建立与温度相关的材料模型;建立考虑残余应力和温度效应的含多组件、多界面、复杂接触的高还原度灌封模块有限元模型,采用内聚力模型来模拟树脂-预埋件界面的失效行为;对高低温循环下灌封模块的应力应变进行仿真,并分析其分布特征和开裂破坏机理。结果表明:无论升温/降温过程,由于灌封树脂与预埋件热膨胀系数不匹配,二者间热应变差值均较大;当温度接近玻璃化转变温度T g时差值急剧扩大,由此产生的热应力叠加残余应力共同引发了灌封模块的界面失效;仿真分析结果与灌封模块高低温循环试验结果吻合良好,验证了分析方法和有限元模型的有效性。研究结果对于灌封模块高可靠性设计具有一定的参考价值。

Aiming at the cracking failure of the modified epoxy resin encapsulated module as a result of interface failure under high low temperature cycles,numerical simulation and experimental studies were carried out.Firstly,the residual stress field in the encapsulated module was reconstructed after measuring the curing residual stresses in epoxy resin using the hole-drilling method.Temperature-dependent material models were developed after testing the mechanical and thermal characteristic parameters of encapsulated module components,such as modified epoxy resin,in high and low temperature conditions.Then,a finite element model of a high-reduction encapsulated module with multiple components,multiple interfaces,and complicated contacts was established considering residual stress and temperature effects.To simulate the failure behaviour of the resin-embedded part interfaces,the cohesive zone model was utilized.Finally,the stress and strain of the encapsulated module under high and low temperature cycles were simulated,and their distribution features and cracking failure mechanism were analyzed.The results indicate that regardless of the heating/cooling process,significant due to a mismatch in thermal expansion coefficients between the resin and the embedded parts.As the temperature approaches the glass transition temperature T g,the difference grows dramatically.The resulting thermal stress,together with the residual stress,led to the interface failure in encapsulated module.The numerical results were in good agreement with the high and low temperature cycle test results of the encapsulated module,which verified the effectiveness of the analysis method and the established finite element model.The investigation provides an important reference for the high-reliability design of the encapsulation module.