凸点材料的选择对器件疲劳特性的影响

为了研究凸点材料对器件疲劳特性的影响,采用非线性有限元分析方法、统一型黏塑性本构方程和Coffin-Manson修正方程,对Sn3.0Ag0.5Cu,Sn63Pb37和Pb90Sn10三种凸点材料倒装焊器件的热疲劳特性进行了系统研究,对三种凸点的疲劳寿命进行了预测,并对Sn3.0Ag0.5Cu和Pb90Sn10两种凸点材料倒装焊器件进行了温度循环试验.结果表明,仿真结果与试验结果基本吻合.在热循环过程中,凸点阵列中距离器件中心最远的焊点,应力和应变变化最剧烈,需重点关注这些危险焊点的可靠性;含铅凸点的热疲劳特性较无铅凸点更好,更适合应用于高可靠的场合;而且随着铅含量的增加,凸点的热疲劳特性越好,疲劳寿命越长.

Effects of Bump Materials Selection on the Fatigue Characteristics of Devices

In order to study the effects of the bump materials on the fatigue characteristics of the device,the thermal fatigue characteristics of three flip-chip devices with Sn3.0Ag0.5Cu,Sn63Pb37 and Pb90Snl0 bumps materials were systematically studied by the nonlinear finite element analysis method,the unified viscoplastic constitutive equation and the Coffin-Manson correction equation.The fatigue life of the three kinds of bumps was predicted.The temperature cycling experiments were carried out on the flip-chip devices with Sn3.0Ag0.5Cu and Pb90Sn10 bumps materials.The results show that the simulation resuhs are in good agreement with the experimental results.In the process of thermal cycling,the stress and strain changes of the solder joints in the bumps array farthest from the center of the device are most significant,and the reliability of these dangerous solder joints should be focused on.The thermal fatigue characteristics of the lead-containing bumps are better than those of the lead-free bumps,and the lead-containing bumps are more suitable for high reliability applications.With the increase of lead content in bumps,the thermal fatigue characteristics of bumps are better and the fatigue life is longer.