随机振动条件下形态结构参数对PBGA无铅焊点应力应变影响分析

STUDY ON IMPACT OF CONFIGURATION PARAMETERS ON PBGA LEAD-FREE SOLDER JOINTS STRESS AND STRAIN UNDER RANDOM VIBRATION LOAD

选取焊点高度、焊盘直径、引脚间距、焊点矩阵四个形态结构参数作为关键因素,采用水平正交表L18(37)设计18种不同形态结构参数组合的塑料封装球栅阵列(plasticballgridarray,PBGA)器件无铅焊点,建立18种PBGA无铅焊点的三维有限元分析模型,并进行随机振动条件下的应力应变有限元分析,得到18种不同形态结构参数的PBGA无铅焊点的应力应变数据,针对应力应变数据进行极差分析与方差分析。结果表明,随机振动条件下四个因素对PBGA无铅焊点应力应变的影响由大到小依次是焊点矩阵、引脚间距、焊点高度和焊盘直径,应力应变最小的焊点最佳形态结构参数水平组合为焊点高度0.32mm、焊盘直径0.30mm、引脚间距0.65mm和焊点矩阵6×6;在置信度为95%的情况下,引脚间距和焊点矩阵对PBGA无铅焊点随机振动应变具有显著影响,焊盘高度和焊盘直径对应变影响不显著。

Solder joint height, pad diameter, lead pitch and ball array were selected as four key configuration parameters, by using an L18 （3^7） orthogonal array, the lead-free solder joints of plastic ball grid array（PBGA） component which have 18 different configuration parameters＇ levels combinations were designed. The 3D finite element analysis models of all the 18 PBGA lead-free solder joints were developed. Using Ansys performed the finite element analysis of the PBGA lead-free solder joints under random vibration load. The maximum values and distributions of stress and strain within PBGA lead-free solder joints were determined. Based on the values of stress and strain the range analysis and the variance analysis were performed. The results of study show that the stress and strain of PBGA lead-free solder joint are affected by the ball array, the lead pitch, the solder joint height and the pad diameter in a descending order under random vibration load, the best level combination of configuration parameters that results in the minimum stress and strain is the solder joint height of 0.32 nun, the pad diameter of 0.30 mm, the lead pitch of 0.65 mm and the ball array of6×6. With 95% confidence, the lead pitch and the ball array have significant effect on the strain of PBGA solder joints whereas the solder joint height and the pad diame- ter has little effect on the strain of lead-free PBGA solder joints under random vibration load.