基于比例风险模型的板级无铅焊点跌落寿命分析

Lifetime analysis of lead-free solder joints under drop impact using proportional hazards model

进行了三组跌落高度下的焊点疲劳寿命试验,采用比例风险模型(PHM)分析跌落高度对焊点寿命分布的影响。PHM模型估计得到的焊点寿命期望(MTTF)及寿命失效概率密度与实验数据都能够较好的吻合,验证了模型的有效性。且由焊点跌落MTTF值随高度变化曲线可看出,当跌落高度略大于0.6 m时焊点MTTF值都小于10次,表明无铅焊点对冲击载荷非常敏感。最后用估计得到的寿命期望结合Miner准则得到板极无铅焊点跌落寿命损伤累积模型。

Three groups of drop impact tests for solder joints were conducted with different drop heights.Proportional hazards model（PHM） was used to evaluate the effect of drop height on the solder joints＇ life span.The mean-time-to failure（MTTF） and the failure probability density function（PDF） estimated by the PHM agree well with the experimental data,and this validates the effectiveness of the PHM.By the curve of MTTF（with respect to different drop heights）,it can be observed that the MTTF10 when the drop height is greater than 0.6m,and this demonstrates that the lead-free solder joints are very sensitive to drop impact.Finally,the estimated lifetime of MTTF was integrated with the Miner＇s law to achieve the cumulative damage model of lead-free solder joints.