Thermal Deformation Measurement for Light Emitting Diode using Digital Image Correlation Method with Spectrograph technique

Abstract

    An effective thermal deformation measurement technique for high power light emitting diode (LED) during emitting the light was developed using digital image correlation method (DICM) with spectrograph. Camera image detected by charge coupled device (CCD) during emitting light from LED was affected by two causes, an intensity of emitting light which depends on wavelength and a radiant intensity of exothermic heat which depends on temperature. Optimization of detected wavelength by band-path filter, in consideration of emission wavelength and surface temperature of the LED with the Plank's radiation law, was absolutely improved quality of CCD camera image. The measured thermal deformation of the encapsulation resin molded the LED on epoxy glass substrate was up to 30μm in z-axis displacement over 400K of exothermic heat temperature with 350mA by the developed technique.