External Efficiency and Thermal Reliability Enhanced Multi-Chip Package Design for Light Emitting Diodes

摘要

With the power of light emitting diodes (LEDs) getting higher and higher, the issue of thermal management is getting much more important. In this paper, we discussed a new idea to get white light without using traditional phosphor and to enhance its extraction efficiency. Microlens is used for increasing external efficiency and shaping light pattern. The location of micro-lens is designed carefully by considering cup reflection. We also revealed that it is important to consider the angle of exit light from LEDs. The result shows our design is suitable for high color rendering index (CRI) application. At the same time, the uniform white light is approached as the light has been strongly diffused. Furthermore, we try to decrease the junction temperature as low as possible so as to increase stability and lifetime of LEDs. In order to maintain color mixing and dissipate heat, multi-chip or four pairs of electrodes which are electroplated with copper after bulk micromachining process within a silicon-based package are used. This novel packaging technique needs just a few processing steps and could be mass produced for nowadays high brightness light emitting diodes (HBLEDs).