Two-Dimensional Photothermal Modeling of Multichip LEDs Device With Thermal Coupling Matrix by Microscopic Hyperspectral Imaging

Abstract

This article presents a method for determining the 2-D peak wavelength distribution of multichip light-emitting diodes (LEDs) devices by relating their spectral properties to junction temperature and by considering thermal coupling factors as well. It is proposed that a theoretical thermal coupling matrix for 2-D photothermal distributions of multichip LED devices can be used to calculate the temperature distribution at a given heat power of each chip. Each chip combination was optimized and evaluated for thermal and spectral uniformity using the proposed method based on a thermal coupling matrix that considers the peak wavelength distribution in the entire 2-D space. The modeling technique was validated experimentally on three-chip modules by infrared thermography and microscopic hyperspectral imaging technique. The experimental results approve that the proposed approach in comparison to a linear method has achieved a more compact set of features along with high accuracy for temperature and peak wavelength distribution. The results clearly show that the prediction of peak wavelength distribution for red, green, and blue LEDs with the proposed model has the largest increase in accuracy, with an average accuracy increase of 67.1%, 40.2%, and 22.4%, respectively.