Influence of Epoxy Viscosity on Led Encapsulation Process

Abstract

There are a few issues experienced in high-power light emitting diode (LED) applications that severely influence the reliability of the LEDs. One of the most problems of the LED failure is wire deformation or wire sweep during the encapsulation process that can indirectly affect the LED life expectancy. The goal of this study was to examine the encapsulation process of the LED and to correlate the impact of viscosity of the epoxy molding compound (EMC) during the LED encapsulation process. The advanced simulation tool, ANSYS Fluent, is utilized to complete an investigation on the fluid–structure interaction (FSI) phenomena between the gold wire bonding and the EMC. The FSI modeling was used to measure the stresses indirectly applied to the gold wire bonding during the encapsulation process. Besides, the volume of the EMC being dispense onto the LED substrate will be simulated by utilizing the volume of fluid (VOF) method. The simulation can be conducted repeatedly by changing the viscosity of the EMC (0.248 kg/m.s, 0.448 kg/m.s, and 0.648 kg/m.s). Parameters such as injection speed, injection time, and inlet contact angle are fixed in this study. The results demonstrated that the wire deformation, stress and strain distributed on the wire bonding increased with increasing viscosity of the EMC. The high viscosity of the EMC would yield higher deformation, stress, and strain distributions of the gold wire bonding.