基于模态分析的倒装芯片缺陷检测

倒装芯片技术逐渐成为微电子封装的主流技术之一，而其中的缺陷检测也日益受到关注。文章针对倒装芯片中典型的焊球缺失缺陷开展研究，以倒装芯片振动模型为基础，推导出芯片振动方程，阐述了缺陷对振动的影响以及利用模态分析进行倒装芯片缺陷检测的原理，并结合实际芯片，理论计算出焊球缺失对其固有频率变化的影响,进一步对正常和焊球缺失芯片的固有频率变化进行了仿真分析和实验测量，研究结果验证了理论计算固有频率变化的正确性，表明基于模态分析的方法可用于倒装芯片的缺陷检测研究。

Defects detection for flip chip using modal analysis

Flip chip has been one of the mainstream technologies in microelectronic packaging, and quality inspection for flip chip has gained more and more attention. Solder bump missing, a typical defect in flip chip, is studied in this paper. The vibration equation of flip chip is deduced based on the vibration model. The influence of defects on the vibration response was described, and the principle of defects inspection for flip chip using modal analysis is presented. The influence of solder bumping missing on the variation of the natural frequencies of flip chip used in the experiments is calculated. Then, the shifting of the natural frequencies of the reference flip chip and flip chips containing defect are simulated and measured in the experiments. The results validates the analytic models, indicating that solder bump missing of the flip chip can be detected using modal analysis. Therefore, the inspection technique can be used to detect defects for flip chip.