基于蠕变模型倒装芯片焊点疲劳寿命预测

采用有限元方法对倒装芯片的焊点进行数值模拟计算分析。结果表明，等效蠕变应变和等效塑性应变的最大值在芯片下的边缘焊点上表面；对焊点应力应变进行时间历程处理，在循环的开始阶段，应力松弛现象显著，同时塑性应变和蠕变应变都存在累积叠加趋势；对应力应变迟滞回线研究，发现曲线呈现周期性变化，随着温度的循环加载并趋于稳定。凭借Solomon模型和Shine and Fox模型，基于塑性应变和蠕变应变的交互作用，计算焊点的疲劳寿命，模拟结果和实际情况基本接近。

Fatigue life prediction for flip chip soldered joints based on creep stain model

Finite element method was used to simulate the inelastic stress in soldered joints of flip chip, and the results indicated that the maximums of equivalent creep strain and equivalent plastic strain in soldered joint both located at the upper surface of limbic chip.Processing the stress and strain of soldered joints with time, it was indicated that soldered joints had significantly relaxed the stress in the initial stage of circulation, with the accumulated trends of plastic strain and creep strain.With the hysteresis loop of stressstrain, cyclical variation of the loop was observed, and the curve became stable with the cyclic loading of heat.On account of the interaction between plastic strain and creep strain, the solomon model and shine and fox model were utilized to calculate fatigue life of the soldered joints.The simulated results were almost the same with the the practical life.