功率VDMOS器件封装热阻及热传导过程分析

Thermal resistance and thermal conduction process analysis of power VDMOS device

热阻是反映电子器件结温的关键热参数,也是指导用户在复杂应用环境中设计热特性的关键参数。本文研究了ITO-220AB封装器件由内至外不同分层材料特性对于器件热阻及热传导的影响。通过测量四种规格VDM OS器件结到环境热阻(R_(thj-a))及结到管壳热阻(R_(thj-c)),并采用结构函数分析法,分析热量从芯片到管壳外的热传导过程发现,随着芯片面积的增大,热阻线性减小,利于器件散热;芯片与框架间过厚的焊锡层非常不利于热量的传导;铜框架厚度间接影响了外部包裹树脂厚度,从而改变了树脂所占器件热阻R_(thj-c)的比例,树脂材料越厚,器件热阻会明显增大。

Thermal resistance is the most important parameter because it not only reflects the junction temperature of electronic devices but also guides the designs of thermal characteristics in complex applications.In this article,the influence of device thermal resistance and thermal conduction with different package materials were studied.The structural function method was utilized for analyzing of heat flow from the chip to case after the thermal resistance test of four VDM OS power devices,including junction to ambient（R（thj-a））,and junction to case（R（thj-c））.The results of experimental test and related analysis show that the thermal resistance linearly decreases with the increase of chip area,which is helpful for heat dissipation;the thick solder betw een chip and frame is bad for heat dissipation;the frame thickness affects the external package resin indirectly causing the change of ratio of resin thermal resistance in R（thj-c）and device thermal resistance increases significantly with thicker resin material.