Electromigration statistics and damage evolution for Pb-free solder joints with Cu and Ni UBM in plastic flip-chip packages
Electromigration statistics and damage evolution for Pb-free solder joints with Cu and Ni UBM in plastic flip-chip packages
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DOI：
10.1007/978-0-387-48433-4_16
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
Seung-Hyun Chae;Xuefeng Zhang;K. Lu;H. Chao;P. Ho;Min Ding;P. Su;T. Uehling;L. Ramanathan
中科院分区：
文献类型：
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作者：
Seung-Hyun Chae;Xuefeng Zhang;K. Lu;H. Chao;P. Ho;Min Ding;P. Su;T. Uehling;L. Ramanathan
通过一系列的电迁移（EM）测试，研究了含Cu和Ni的无铅凸金属化焊点的寿命统计和损伤演变。发现电磁寿命取决于所使用的失效准则，因此基于第一次电阻跳变和常规开路失效准则的结果进行了比较。基于开路失效准则，使用Cu UBM的焊点寿命比使用Ni UBM的焊点寿命长，但当采用第一个电阻跳变准则时，使用Ni UBM的焊点寿命与使用Cu UBM的焊点寿命相当。为了确定焊点温度，采用实验和有限元分析相结合的方法研究了焦耳热效应。当施加1 A电流时，焊点的温度比硅晶片表面的温度高约15℃。在适当的温度校正下，基于Cu和Ni UBM焊点开断准则的活化能和电流密度指数分别为q = 1.11 eV、n= 3.75和q = 0.86 eV、n= 2.1。基于第一电阻跳变判据，Cu UBM的Q= 1.05 eV,n= 1.45； Ni UBM的Q= 0.94 eV,n= 2.2。对于含Cu UBM的焊点，首先在Cu6Sn5/钎料界面处形成空洞，而最终在Cu3Sn/Cu6Sn5界面处出现开口破坏。对于Ni UBM，在Ni3Sn4/钎料界面处首先形成空洞，导致同一界面失效。在电流应力作用下，金属间化合物（IMCs）的形成增强，且随时间呈线性增长。IMC的增长伴随着体积的收缩，加速了EM作用下损伤的演化。
A series of electromigration (EM) tests were performed as a function of temperature and current density to investigate lifetime statistics and damage evolution for Pb-free solder joints with Cu and Ni under-bump-metallizations (UBMs). The EM lifetime was found to depend on the failure criterion used, so the results were compared based on the first resistance jump and conventional open-failure criterion. Solder joints with Cu UBM had a longer lifetime than Ni UBM based on the open-failure criterion, but the lifetime with Ni UBM became comparable when the first resistance jump criterion was applied. To determine the temperature in solder joints, the Joule heating effect was investigated with experiments and finite element analysis. The temperature of solder joints was determined to be approximately 15°C higher than that at the Si die surface when 1 A of current was applied. With the appropriate temperature correction, the activation energies and the current density exponents were found to beQ= 1.11 eV,n= 3.75 andQ= 0.86 eV,n= 2.1 based on the open-failure criterion for solder joints with Cu and Ni UBM, respectively. Based on the first resistance jump criterion,Q= 1.05 eV,n= 1.45 for Cu UBM andQ= 0.94 eV,n= 2.2 for Ni UBM, respectively. For solder joints with Cu UBM, voids were formed initially at the Cu6Sn5/solder interface while the final open failure occurred at the Cu3Sn/Cu6Sn5interface. For Ni UBM, voids were formed initially at the Ni3Sn4/solder interface leading to failure at the same interface. The formation of intermetallic compounds (IMCs) was enhanced under current stressing, which followed linear growth kinetics with time. The IMC growth was accompanied by volume shrinkage, which accelerated damage evolution under EM.