Measurement System for Phosphor Dispensing Shape of LED Chip Package Using Machine Vision

머신비전에 의한 LED Chip Package 형광물질 토출형상 측정

  • Received : 2013.03.29
  • Accepted : 2013.05.09
  • Published : 2013.05.31


In this study, an efficient machine vision based inspection system is developed for the in-line measurement of phosphor resin dispensing shapes on LED chip package. Since the phosphor resin (target material) has semitransparent characteristics, illuminated light beam is reflected from the bottom of the chip as well as from the surface. Since such phenomenon can deteriorate inspection reliability, a white LED and a 635nm laser slit beams are experimentally tested to decide suitable illumination optics. Also, specular and diffuse reflection methods are tested to decide suitable optical triangulation. As a result, it can be known that the combination of a white slit beam source and specular reflection method show the best inspection results. The Catmull-Rom spline interpolation is applied to the obtained data to form smoother surface. From the results, it can be conclude that the developed system can be sucessfully applied to the in-line inspection of LED chip packaging process.


Dispensing;In-line inspection;Machine vision;LED chip package


Grant : LED Encapsulation 장비 및 통합공정 개발


  1. M. Fan, M. Liang, D. Guo, F. Yang, L. Wang, G. Wang, and J. Li, "Color Filter-less Technology of LED Back Light for LCD-TV," Proc. SPIE, Vol. 6841, pp. 68410G1-68410G6, 2007 DOI:
  2. J. R. Ryu, "The Improvement for Performance of White LED chip using Improved Fabrication Process", Journal of the Korea Academia-Industrial Cooperation Society, Vol. 13, No. 1, pp. 329-332, 2012 DOI:
  3. S. W. Lee, D. J. Choi, C. K. Song, and M. G. Chun, "LED Inspection System of Post-Molding Process using Image Processing", Journal of Korean Institute of Information Technology, Vol. 10, No. 5, pp.17-27, 2012 DOI:
  4. D. H. Cho, and J. Y. Lee, "The Enhanced LED Dispensing Processing System", The Institute of Electronics Engineers of Korea, Vol. 45, No. 4, pp.42-46, 2008
  5. K. Kooijman, and J. Horijon, "Video rate laser scanner: Considerations on triangulation optics, detector and processing circuits", Proceedings of SPIE, Vol. 2065, pp.251-263, 1994 DOI:
  6. E. Catmull, and R. Rom, "A class of local interoilating splines", Computer Aided Geometric Design, Academic Press, San Francisco, 1974
  7. S. J. Ha, Y. K. Cho, M. W. Cho, K. C. Lee, and W. H. Choi, "Process Capability Optimization of a LED Die Bonding Using Response Surface Analysis", Journal of the Korea Academia-Industrial cooperation Society, Vol. 13, No. 10, pp.4378-4384, 2012 DOI:

Cited by

  1. A Study on High Viscosity Phosphor Dispensing Process for Implementation of High-Efficiency White LED vol.20, pp.2, 2014,
  2. Development of Dispenser System with Electrohydrodynamic and Voice Coil Motor for White Light Emitting Diode vol.16, pp.10, 2015,
  3. A Study of High Viscosity Phosphor Dispensing for an Electrostatic Printing System vol.24, pp.2, 2015,