A novel approach for flip chip solder joint inspection based on pulsed phase thermography
A novel approach for flip chip solder joint inspection based on pulsed phase thermography
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基于脉冲相位热成像的倒装芯片焊点检测新方法
DOI：
10.1016/j.ndteint.2011.05.003
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发表时间：
2011-10-01
影响因子：
4.2
通讯作者：
Shi, Tielin
中科院分区：
文献类型：
--
作者：
Lu, Xiangning;Liao, Guanglan;Shi, Tielin
表面贴装元件在微电子封装中得到了广泛的应用。然而，随着焊料凸点向微细间距和高密度方向发展，这给缺陷检测带来了巨大的挑战。传统的无损检测方法由于其自身的缺陷，在焊点评估中存在不足。因此，有必要探索新的焊点检测方法。研究了一种基于脉冲相位热像技术的焊点缺陷识别新方法。在这种方法中，测试芯片受到热脉冲的刺激，随后的瞬态响应被商业热成像仪捕获。为了提高信号的信噪比，采用了空间和时间滤波技术。将记录的热谱图输入到具有5x 5掩模的改进的中值滤波器，并且提取每个像素的温度演变并通过移动平均操作进行平滑。然后用指数函数拟合温度-时间曲线。为了消除发射率变化和加热不均匀性，我们使用快速傅立叶变换将时域中的拟合温度值转换为频域中的相位信息。在低频范围内，缺陷区的相频曲线与健全区的相频曲线相区别。实验结果表明，该方法能够有效地识别漏焊凸点，可用于高密度封装焊点的检测。(C)2011爱思唯尔有限公司版权所有，
Surface mount components have been extensively used in microelectronic packaging. However, it brings great challenge for defect inspection with the development of solder bumps towards ultra-fine pitch and high density. Traditional nondestructive detection methods are insufficient for solder joint assessment due to their own disadvantages. Therefore, it is necessary to explore new methods for solder joint inspection. A novel approach based on the pulsed phase thermography was investigated for identifying the defects of solder joints. In this approach, the test chip was stimulated by a thermal pulse, and the consequent transient response was captured by a commercial thermal imager. The spacial and temporal filtering techniques were adopted to improve the signal to noise ratio. The recorded thermograms were input to an improved median filter with a 5 x 5 mask, and the temperature evolution of each pixel was extracted and smoothed by the moving average operation. Then the temperature-time curve was fitted with an exponential function. To eliminate emissivity variations and heating non-uniformity, we converted the fitted temperature values in time domain to the phase information in frequency domain using the fast Fourier transform. In low frequency range, the phase-frequency curve of the defect area was differentiated from that of the sound area. The results demonstrate that this approach is effective for identification of the missing bumps, and can be used in the solder joint inspection in high density packaging. (C) 2011 Elsevier Ltd. All rights reserved,