大功率氮化镓基白光LED模组的散热设计

Thermal Design of GaN-based High-power LED Module

散热设计是大功率发光二极管(LED)模组结构设计的重要环节。首先利用计算流体力学方法对自然对流条件下大功率LED模组的温度场进行了模拟,提出并优化了模组可采用的散热片结构,进而对影响模组散热的其他关键因素进行了分析,结果表明,提高关键封装材料如银胶的热导率能够有效地降低芯片温度,提高芯片温度均匀性;多芯片封装时芯片的整体温度及均匀性相对于单芯片封装皆有改善。优化后的封装结构在5 W电功率注入条件下,芯片结温约60℃。

Thermal management is the key issue for LED module design because luminous efficiency and lifetime of high-power GaN-based white LEDs are limited by heat dissipation. Temperature distribution of LED module under natural convection was simulated using computational fluid dynamics, and structure of fin for 5 W LED module was brought forward and optimized. Then, other key issues impacting heat dissipation were analyzed. The results show that junction temperature can be dramatically decreased by increasing thermal conductivity of attaching materials, and temperature characteristics of multi-chip package are superior to that of single-chip package both in junction temperature and chip temperature uniformity. The junction temperature of chip of the optimized module is about 60 ℃ under 5 W injection power.