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

• DOI: 10.5762/kais.2013.14.5.2113
• Publication Date: 2013-07-08T02:53:26Z
• Authors: Seok-Jae Ha; Jong-Su Kim; Myeong-Woo Cho; Jong-Myung Choi
• Keywords: 03 medical and health sciences; 0302 clinical medicine

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.