Detection of solder bump defects on a flip chip using vibration analysis
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- 作者：Junchao Liu (1)
Tielin Shi (2)
Qi Xia (1)
Guanglan Liao (1) guanglan.liao@mail.hust.edu.cn - 关键词：flip chip – ; defect detection – ; ultrasonic excitation – ; vibration analysis
- 刊名：Frontiers of Mechanical Engineering
- 出版时间：March 2012
- 出版年：2012
- 期刊代码：pc510_2095-0233
- 类别：et
- 卷：7
- 期：1
- 页码：29-37
- 数据来源：sp
摘要
Flip chips are widely used in microelectronics packaging owing to the high demand of integration in IC fabrication. Solder bump defects on flip chips are difficult to detect, because the solder bumps are obscured by the chip and substrate. In this paper a nondestructive detection method combining ultrasonic excitation with vibration analysis is presented for detecting missing solder bumps, which is a typical defect in flip chip packaging. The flip chip analytical model is revised by considering the influence of spring mass on mechanical energy of the system. This revised model is then applied to estimate the flip chip resonance frequencies. We use an integrated signal generator and power amplifier together with an air-coupled ultrasonic transducer to excite the flip chips. The vibrations are measured by a laser scanning vibrometer to detect the resonance frequencies. A sensitivity coefficient is proposed to select the sensitive resonance frequency order for defect detection. Finite element simulation is also implemented for further investigation. The results of analytical computation, experiment, and simulation prove the efficacy of the revised flip chip analytical model and verify the effectiveness of this detection method. Therefore, it may provide a guide for the improvement and innovation of the flip chip on-line inspection systems.