Reliability analysis of RGB LED on low-temperature thermo-mechanical coupling field

LED with many advantages such as high brightness, long-lifetime, and energy-saving has been successfully applied to various fields, especially on special lighting applications. At low temperatures, LED is more uniform in illumination and has a higher luminous efficiency, which is regarded as the next generation refrigeration system lighting. As well as in some cold regions, LED has also become the main source of lighting. However, in the actual circumstances of low temperature, the scope of LED lighting is limited to a great many of reliability problems. Accounting to the issues above, the comparative analysis between RGB LED which has a better performance on photoelectric properties and common GaN-based LED based on the finite element method will be taken in this paper. With ANSYS software, the temperature distribution in the multi-physics low temperature coupling field can be attained between chips with different epitaxial materials and the internal structure of LED, further on the corresponding VONMEIS equivalent stress and strain of major components in LED. So that inferring the failure modes and failure mechanisms of RGB LED in low thermal mechanical coupling field. The following conclusions will be found, in the ambient temperature changing process, the temperature of components changes linearly along with the temperature gradient when it reaches a steady state. The location of the max stress and the max strain is the corners of the surface between Die attach layer and Slug, the relationship between stress, strain and temperature is a non-linear function. In the RGB LED, the thermal stress gradient of the substrate and Die attach layer are large, which is prone to fatigue damage to the main reason. Meanwhile, the reliability of green and blue chip are better than red chip. Based on the results of this paper, some methods will be proposed to improve the reliability of RGB LED.