3-Dimensional Micro Solder Ball Inspection Using LED Reflection Image

  • Kim, Jee Hong (Department of Display Engineering, Pukyong National University)
  • Received : 2019.07.03
  • Accepted : 2019.07.12
  • Published : 2019.09.30


This paper presents an optical technique for the three-dimensional (3D) shape inspection of micro solder balls used in ball-grid array (BGA) packaging. The proposed technique uses an optical source composed of spatially arranged light-emitting diodes (LEDs) and the results are derived based on the specular reflection characteristics of the micro solder balls for BGA A vision system comprising a camera and LEDs is designed to capture the reflected images of multiple solder balls arranged arbitrarily on a tray and the locations of the LED point-light-source reflections in each ball are determined via image processing, for shape inspection. The proposed methodology aims to determine the presence of defects in 3D BGA shape using the statistical information of the relative positions of multiple BGA balls, which are included in the image. The presence of the BGA balls with large deviations in relative position imply the inconsistencies in their shape. Experiments were conducted to verify that the proposed method could be applied to inspection without sophisticated mechanism and productivity problem.


3D Inspection;Solder Ball;BGA;Vision


Supported by : Pukyong National University


  1. J. H. Kim, C. D. Nguyen, "Shape Recognition of a BGA Ball using Ring Illumination," Journal of Institute of Control, Robotics and Systems, vol.19, pp.960-967, Nov. 2013.
  2. Y. S. Park, J. S. Kim, "A Study on the Vision Inspection System for the Defects Detection of Micro-BGA Device,"J. Korean Precision Engineering, vol. 24, pp.44-48, Apr. 2007.
  3. M. Y. Kim, "Three-dimensional Machine Vision System based on Moire Interferometry for the Ball Shape Inspection of Micro BGA Packages," J. Microelectron. Packag. Soc., vol. 19, pp.81-85, Jan. 2012.
  4. Z. Feng, J. C. Gonzalez, S. Tang, M. Kurwa, E. Krastev, "Non-destructive Techniques for Identifying Defect in BGA Joints: TDR, 2DX, and Cross-section/SEM Comparison," Proc. SMTA International Conference, Orlando, USA, Aug. 2008.
  5. K. W. Ko, H. S. Cho, "Solder Joint Inspection Using a Neural Network and Fuzzy Rule-Based Classification Method," IEEE Tr. Electronic Packaging Manufacturing, vol. 23, pp.93-103, Apr. 2000.
  6. H. Saito, K. Omata, and S. Ozawa, "Recovery of Shape and Surface Reflectance of Specular Object from Relative Rotation of Light Source," Image and Vision Computing, vol. 9, pp.777-787, Sep. 2003.
  7. S. K. Nayer, A. C. Sanderson, L. E. Weiss, and D. D. Simmon, "Specular surface inspection using structured highlight and Gaussian image," IEEE Trans, on Robotics and Automation, vol. 6, pp.208-218, Apr. 1990.
  8. K. S. Kim, J. S. Kim, H. N. Joo, "A Study on the 2-Dimensional Vision Inspection Algorithm for the Defects Detection of BGA Device", J. Korean Institute of Illumination and electrical Installation Engineers, Vol. 19, No. 7, pp53-59 (2005)
  9. J. H. Kim, "Estimation of the 3-D Shape Surfaces with Specular Reflection", J. Optical Society of Korea, Vol. 18, No. 6, pp672-678 (2014)
  10. J. H. Kim, "Three-dimensional shape estimations of specular objects using LED array reflection", Optical Engineering, Vol. 55(12), 123109 (2016)