热冲击条件下LGA焊点可靠性分析及优化  

Reliability analysis and optimization of LGA solder joints under thermal shock conditions

作　　者：翟茂欣 倪屹 时广轶 余未 ZHAI Maoxin;NI Yi;SHI Guangyi;YU Wei(School of Integrated Circuits,Jiangnan University,Jiangyin 214401,China;Wuxi Bewis Sensing Technology Co.,Ltd.,Wuxi 214072,China)

机构地区：[1]江南大学集成电路学院,江苏江阴214401 [2]无锡北微传感科技有限公司,江苏无锡214072

出　　处：《空天预警研究学报》2024年第5期358-363,共6页JOURNAL OF AIR & SPACE EARLY WARNING RESEARCH

摘　　要：为提高栅格阵列封装(LGA)焊点可靠性,采用ANAND本构模型描述SAC305无铅焊点的力学行为,利用有限元分析法和基于能量的Darveaux疲劳寿命预测模型,分析了LGA焊点在热冲击载荷(-55℃~125℃)下的应力应变分布、粘塑性应变能密度和疲劳寿命;利用田口试验评估了焊点高度、塑封料热膨胀系数、BT基板热膨胀系数、焊盘热膨胀系数四个因子对焊点疲劳寿命的影响,并提出最优设计方案.实验结果表明,热冲击载荷下,距离几何中心最远的LGA焊点应力值最大且呈周期性变化;影响焊点疲劳寿命的主要因子是塑封料热膨胀系数和焊点高度,优化后焊点的等效塑性应变能密度增量减小了57%,热疲劳寿命是优化前的2.32倍,提高了LGA焊点结构的热可靠性.In order to improve the reliability of solder joints of land grid array(LGA),the ANAND constitutive model is used to describe the mechanical behavior of SAC305 lead-free solder joints.The stress-strain distribution,the viscoplastic strain energy density and the fatigue life of LGA solder joints under the thermal shock load(-55℃~125℃)are analyzed by using finite element analysis method and the energy-based Darveaux fatigue life prediction model.Finally,Taguchi test is employed to evaluate the effects of the four factors of solder joint height,thermal expansion coefficient(TEC)of plastic sealing material,BT substrate TEC,and pad TEC on fatigue life of solder joints,and the optimal design scheme is also proposed.The experimental results are shown as follows:Under the thermal shock load,the stress value of the LGA solder joint farthest from the geometric center is the high-est and varies periodically.The main factors affecting the fatigue life of solder joints are the TEC of plastic sealing material and the height of solder joints.After optimization,the increment of equivalent plastic strain energy density of solder joints is reduced by 57%;the thermal fatigue life is 2.32 times of that before optimization.Obviously,the thermal reliability of LGA solder joint structure is improved.

关 键 词：栅格阵列封装焊点 有限元分析 温度冲击 疲劳寿命 

分 类 号：TN406[电子电信—微电子学与固体电子学]