Hu Xingwang, Liu Li, Liu Sheng, Ruan Meng, Chen Zhiwen
The Institute of Technological Sciences of Wuhan University, Wuhan University, Wuhan 430072, China.
School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430072, China.
Micromachines (Basel). 2023 Feb 28;14(3):588. doi: 10.3390/mi14030588.
Under alternating temperatures, the fatigue failure of solder balls caused by the mismatch of the thermal expansion coefficient is a key problem in a Ball Grid Array (BGA). However, the combined effects of the solder ball location and the size of voids within it can seriously affect the thermal fatigue reliability of BGA solder balls, which can be easily ignored by researchers. Firstly, the thermal fatigue reliability of the board-level solder balls was evaluated by a temperature cycling test of the BGA package at -20 °C-+125 °C. The experimental results showed that the thermal fatigue reliability of the outer ring's solder joint was lower than that of the inner ring. Secondly, the reliability of the solder balls in the BGA package was studied under the same thermal cycling condition based on finite element analysis (FEA). The influences of voids on fatigue life were investigated. Generally, a linear correlation between the void content and the fatigue life of the inner rings' solder balls could be identified with a gradually smoothed relationship for solder balls closer to the center. In addition, when the size of the void exceeded a critical volume, the inner ring's solder ball with the void would fail before the outermost ring. The results of FEA showed that the critical void volume ratio from the second to fifth ring increased from 10.5% to 42.3%. This study provides a valuable reference for the influence of voids on the thermal fatigue reliability of BGA solder balls.
在交替温度下，由热膨胀系数不匹配导致的焊球疲劳失效是球栅阵列（BGA）中的一个关键问题。然而，焊球位置及其内部空洞尺寸的综合影响会严重影响BGA焊球的热疲劳可靠性，而这一点很容易被研究人员忽视。首先，通过对BGA封装在-20°C至+125°C温度循环测试来评估板级焊球的热疲劳可靠性。实验结果表明，外圈焊点的热疲劳可靠性低于内圈。其次，基于有限元分析（FEA），在相同热循环条件下研究了BGA封装中焊球的可靠性。研究了空洞对疲劳寿命的影响。一般来说，内圈焊球的空洞含量与疲劳寿命之间存在线性关系，对于更靠近中心的焊球，这种关系逐渐趋于平缓。此外，当空洞尺寸超过临界体积时，带有空洞的内圈焊球会比最外圈焊球先失效。有限元分析结果表明，从第二圈到第五圈，临界空洞体积比从10.5%增加到42.3%。本研究为空洞对BGA焊球热疲劳可靠性的影响提供了有价值的参考。
