基于模糊理论的随机振动条件下叠层PBGA焊点可靠性分析

Reliability study of stacked PBGA soldered joint at random vibration loading based on fuzzy theory

对叠层塑料球栅阵列(plastic ball grid array package,PBGA)焊点在随机振动条件下的可靠性进行了研究.通过模态分析,提取固有频率和振型,接着进行随机振动分析,得到叠层PBGA焊点的应力分布特性;引入模糊理论修正钎料的应力—寿命曲线(S-N curve),并结合三带技术对叠层PBGA焊点随机振动疲劳寿命进行了计算.结果表明,组件在一阶固有频率下振动时,芯片处的振幅最大;组件边角叠层焊点受到的应力最大,且芯片侧应力大于PCB侧;模糊理论的引入使得1σ与2σ应力水平对叠层PBGA焊点产生的损伤得以考虑,从而实现对叠层PBGA焊点振动疲劳寿命更准确预测.

The reliability of PBGA assembly with stacked soldered joint was analyzed at the random vibration loading.The natural frequency and mode shape were extracted by mode analysis,and then the random vibration analysis was carried out to analyze stress distribution characteristic of stacked PBGA soldered joint,the S-N curve of the solder was modified by fuzzy theory,which was combined with three band technology to estimate the vibration fatigue life of stacked PBGA soldered joint.The results show that the position of maximum amplitude is PBGA chip location when PBGA assembly vibrating under the first order natural frequency.The stress in the stacked PBGA soldered joint is not uniformly distributed under the random vibration loading condition,and the stress in the chip side is larger than that in PCB side.Since the damage of stacked PBGA soldered joint caused by 1 and 2 was considered by introducing the fuzzy theory,the stacked PBGA solder joint fatigue life could be accurately predicted.