基于响应曲面法的BGA焊点结构参数优化设计

Structure optimization design of BGA solder joints based on surface response method

球栅阵列(ball grid array package,BGA)封装因其成本低、电气性能好而被广泛应用于集成电路产业中.文中建立了BGA三维模型,将等效应力作为响应目标,选取焊点直径、焊点高度、焊点间距、芯片厚度作为设计因子,采用响应曲面法设计了25组不同水平组合的焊点结构参数进行仿真计算,并基于遗传算法分析对焊点结构热振可靠性进行了优化.结果表明,焊点间距对BGA结构热振可靠性有重要影响;优化方案组合为焊点直径0.28 mm,焊点高度0.20 mm,焊点间距0.40 mm.经过优化验证分析,该优化方案较原始设计方案等效应力降低了11.92%,实现了BGA器件焊点参数优化目的.

Due to low cost and good electrical performance,BGA packaging is widely used in integrate circuit(IC)industry.Finite element method(FEM)analysis was carried out for evaluation of stress distribution in the Ball Grid Array(BGA)solder joints,and the radial scale,the height,the spacing of the solder joints,the height of chip were selected as design factors.Response surface methodology(RSM)was used to generate 25 designs and finite element modeling was employed to simulate the response of the assemblies to reliability influencing simulation calculations.The equation regression was associated with genetic algorithm(GA)to search for an optimal combination of parameters that meet the thermal vibration quality characteristics.The confirmation results showed that the space played a role in the reliability,and the radical scale 0.28 mm,the height 0.20 mm,the spacing 0.4mm settings of produce optimal assembly which demonstrated potential of reducing equivalent stress of the best design by 11.92%,respectively.The aim of optimizing BGA solder joints parameters was succeeded.Highlights:(1)The combination of finite element simulation and genetic algorithm,and the combination of finite element and mathematical statistics methods are confirmed.The interdisciplinary application is carried out.(2)The significant factors for the thermal vibration reliability of BGA solder joints are screened out by mathematical statistical analysis,and the factor weights are sorted,and the positive and negative effects of solder joint stress changes corresponding to the changes of each factor are studied.(3)A more accurate mathematical prediction model is proposed,and the simulation results show that the prediction error of the prediction model is only 2.73%,and the optimization purpose is achieved.(4)The finite element results show that the recommended combination of solder joint diameter of 0.28 mm,solder joint height of 0.20 mm,and solder joint spacing of 0.40 mm has excellent thermal vibration and mechanical properties,which are all required for mobile equipment and will be helpful to people in the industry.The research has certain reference value.