高密度、高性能集成电路主要封装技术采用球栅阵列封装(ball grid array,BGA),其高密度Sn-Pb焊球在极端高、低温及湿热环境的影响下可靠性无法保证.为解决温度变化产生的热膨胀问题,笔者通过有限元仿真计算BGA电路中焊球在高、低温交替循环应力下瞬态黏塑性应变范围,并采用改进的Coffin-Manson经验方程计算器件在温度循环试验下的热疲劳寿命;此外,进一步采用准静态剪切和拉脱试验分析分别经过温度循环及高压蒸煮环境试验后焊球的力学性能,同时采用扫描电子显微镜(scanning electron microscopy,SEM)和能谱分析仪(energy dispersive spectroscopy,EDS)对焊球切面进行分析.研究表明:焊球在温度循环试验下具有较长的疲劳寿命,在不考虑焊球导电与连接性能的前提下,适当环境应力的影响可促使焊球与焊盘界面区域金属间化合物的生成,有效增强了焊球的剪切力学性能.
Simulation and Mechanical Properties of Ball Grid Array Solder Balls under Environmental Stress
Ball grid array(BGA)was recognized as the main packaging of high-density and high-performance integrated circuits(IC).However,the reliability of tin-lead solder balls could not be further guaranteed under the influence of extreme thermal,corrosion and humid environments.In order to consider the thermal expansion problem caused by temperature changes,the transient viscoplastic strain range of solder balls in BGA circuits under thermal cycling load condition was calculated.Meanwhile,Coffin-Manson empirical equation was used to figure out the cycle number of thermal fatigue through finite element simulation.Besides,quasi-static shear and tensile test had been carried out to analyze the mechanical properties of solder balls after thermal cycling,salt atmosphere and pressure cooker test(PCT)respectively.The cross-section of solder balls were also analyzed by means of scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).This research indicates this type of IC has more cycle times than that in appraisement.Furthermore,appropriate accelerated stress test and environmental test condition promote the formation of intermetallic compounds,which enhancing the shear mechanical properties of solder balls effectively.
国家科技期刊平台
NSTL
万方数据
维普
