ZHANG Jun-sheng1,2, WANG Ming-quan2, WANG Yu2, WANG Jun3, GUO Jin-qin1
（1. Dept. of Electronic Engineering, Taiyuan Institute of Technology, Taiyuan 030008, China； 2. School of Information and Communication Engineering, North University of China, Taiyuan 030051, China； 3. School of Materials and Science and Engineering, North University of China, Taiyuan 030051, China）
Abstract： Voids are one of the major defects in ball grid array (BGA) solder joints due to a large amount of outgassing flux that gets entrapped during reflow.X-ray nondestructive machines are used to make voids visible as lighter areas inside the solder joints in X-ray images for detection.However, it has always been difficult to analyze this problem automatically because of some challenges such as noise, inconsistent lighting and void-like artifacts. This study realized accurate extraction and automatic analysis of void defects in solder joints by adopting a technical proposal, in which Otsu algorithm was used to segment solder balls and void defects were extracted through opening and closing operations and top-hat transformation in mathematical morphology. Experimental results show that the technical proposal mentioned here has good robustness and can be applied in the detection of voids in BGA solder joints.
Key words： ball grid array (BGA); void defect; X-ray; Otsu; mathematical morphology
CLD number： TP391.4 Document code： A
Article ID： 1674-8042（2017）02-0199-06 doi： 10.3969/j.issn.1674-8042-2017-02-014
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BGA焊点空洞缺陷的数字形态学检测
张俊生1,2， 王明泉2， 王玉2， 王军3， 郭晋秦1
（1. 太原工业学院 电子工程系， 山西 太原 030008； 2. 中北大学 信息与通信工程学院， 山西 太原 030051； 3. 中北大学 材料科学与工程学院， 山西 太原 030051）
摘要:空洞缺陷是BGA焊接缺陷中比较常见的一种， 主要由回流焊时产生的气体没有及时排出而导致。 X射线无损检测技术可以使空洞缺陷在焊球图像上显示为白色区域供技术人员查看， 但在噪声、不均匀照射、存在与缺陷类似目标的干扰下如何准确地自动提取缺陷一直是个难题。 提出使用Otsu算法分割焊球， 使用数学形态学中的开闭运算、 顶帽变换提取空洞缺陷的技术方案， 实现每个焊点空洞缺陷的准确提取和自动分析。 实验结果表明， 提出的技术方案鲁棒性强， 可应用于BGA焊点的空洞缺陷检测。
关键词:球阵列封装（BGA）； 空洞缺陷； X-射线； Otsu算法； 数学形态学
引用格式：ZHANG Jun-sheng, WANG Ming-quan, WANG Yu, et al. Void defect detection in BGA solder joints using mathematical morphology. Journal of Measurement Science and Instrumentation, 2017, 8(2)： 199-204. ［doi： 10.3969／j.issn.1674-8042.2017-02-014］
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