The Study on Cracking Reasons of LED Encapsulation Silicone

Abstract

Light emitting diodes (LEDs) are increasingly widely used as a new generation of environmentally friendly green light source. However, during the use of LED especially white LED, due to the action of light, heat, etc., the failure phenomenon of cracking of the LED encapsulation adhesive is likely to occur, which will adversely affect the light efficiency and color temperature of LED and even dead lights. In this paper, through analyzing the cases of LED encapsulation adhesive cracking it is concluded that there are two main reasons for LED encapsulation adhesive cracking. One is that the LED lamp beads are affected by light and heat for a long time, which makes the encapsulation adhesive aging and hardening, leading to the cracking of the encapsulation adhesive. The other is due to the thermal mismatch between the encapsulation adhesive and the plastic part of lead frame, which causes the encapsulation adhesive to crack during the process of thermal expansion.