摘要
IC产品的小型化和多功能化使微电子封装密度不断提高,微焊球技术得以广泛应用,而微焊球尺寸和间距日益缩减,使隐藏于芯片或封装内部的微焊球缺陷检测变得十分困难。主动红外热成像技术被深入研究并应用于微焊球缺陷检测,构建了主动红外微焊球缺陷检测模型,并展开试验研究。对直径和间距较大的BGA焊球采用红外透射式测量法进行检测,对获得的热图像进行空间自适应滤波,然后通过边缘检测分割出焊球区域,减小了热噪声和焊球间隙噪声对缺陷识别的干扰,并通过有效热斑面积进行量化分析;对凸点直径和间距较小的FA10倒装芯片采用红外反射式测量法进行检测,利用改进的自适应滤波算法去除空间椒盐噪声,然后提取像素点温度序列值进行时间域移动平均降噪,并以指数形式进行曲线拟合,通过傅里叶变换进行时频转换,采用脉冲相位法解决了表面发射率差异引起的缺陷辨识度下降等问题,并使用低频段的相位信息进行表征分析。利用主动红外热成像技术实现了焊球缺陷的有效检测,为高密度IC封装及其可靠性分析提供了一种快速、有效的方法。
The miniaturization and multifunctionality of IC device promote the improvement of microelectronic packaging. The solder bump technology is widely used in IC packaging. With shrinking of the solder bumps in size and pitch, defect inspection becomes more challenging for the hidden bumps. Active infrared thermography is investigated for detecting the solder bump defect. A mathematical model for infrared inspection of solder bumps is constructed and is validated by the experiments. The BGA balls with larger diameter and pitch are tested in transmissive way. The captured thermal images are processed by using an adaptive filter, and the solder balls are segmented from the image through the edge detection, which reduces the influence of thermal noise on defect identification. The area of hot spot corresponding to the solder balls are calculated for quantitative analysis. The tested chip FA10 with smaller solder bumps is also detected using the active thermography in reflective way. The salt and pepper noise is removed by using an improved adaptive filtering algorithm. The extracted temperature values are smoothed by the moving averaging operation, and then are fitted with an exponential function. The fitted temperature values are converted to the phase information by using fast Fourier transform. The missing bumps are distinguished from the reference bumps through the phase information at low frequency. The active thermography is proved to be a fast and effective method for defects inspection of solder bump in high-density IC packaging.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2016年第10期17-24,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金(51305179)
江苏省自然科学基金(BK20130229)
数字制造与装备技术国家重点实验室开放基金(DMETKF2016005)资助项目
关键词
焊球
主动红外
热图像
温差
solder bump
active infrared
thermography
temperature difference
