基于Darveaux模型的BGA焊点寿命预测影响因素研究

以微系统封装结构中球栅阵列封装(BGA)焊点为研究对象,对热循环载荷下Darveaux模型疲劳寿命预测方法的影响因素进行了探讨.结合有限元仿真分析,分别讨论了裂纹扩展相关系数、粘塑性应变能密度增量和断裂特征长度对Darveaux模型寿命预测结果的影响,揭示了目前焊点可靠性研究中对Darveaux寿命模型在使用时影响因素考虑不充分的现状,并给出了如何考虑上述影响因素的相关建议.进一步,基于蒙特卡洛抽样的全局敏感度分析方法,研究了不同断裂特征长度下,疲劳寿命对Darveaux模型中材料参数的敏感性.研究结果为热循环载荷下正确使用Darveaux模型来预测微系统封装结构的热疲劳寿命提供了有益的参考,为这些关键因素的确定提供了合理性建议与参考依据.

Numerical and Experimental Investigations of the Thermal Fatigue Lifetime of CBGA Packages

A thermal fatigue lifetime prediction model of ceramic ball grid array(CBGA)packages is proposed based on the Darveaux model.A finite element model of the CBGA packages is established,and the Anand model is used to describe the viscoplasticity of the CBGA solder.The average viscoplastic strain energy density increment △Wave of the CBGA packages is obtained using a finite element simulation,and the influence of different structural parameters on theWave is analyzed.A simplified analytical model of the △Wave is established using the simulation data.The thermal fatigue lifetime of CBGA packages is obtained from a thermal cycling test.The Darveaux lifetime predictionmodel ismodified based on the thermal fatigue lifetime obtained fromthe experiment and the corresponding △Wave.A validation test is conducted to verify the accuracy of the thermal fatigue lifetime prediction model of the CBGA packages.This proposed model can be used in engineering to evaluate the lifetime of CBGA packages.

基于柔性基板的叠层CSP无铅焊点热疲劳可靠性研究

近年来随着柔性印制电路新材料、新工艺技术的发展,柔性基板叠层CSP封装中的应用受到人们的广泛关注。本文通过有限元方法对该器件进行了热疲劳非线性分析,得到了该器件焊点阵列的应力、等效塑性应变能密度分布规律并确定关键焊点的位置。通过对该器件焊点热疲劳寿命的统计分析,发现焊点的热疲劳寿命符合双参数威布尔分布,本文给出了Sn3.5Ag0.75Cu和96.5Sn3.5Ag两种钎料情况下器件焊点的威布尔分布和概率密度分布数学模型,并计算得到了该器件焊点的平均热疲劳失效寿命。