大气与真空下功率VDMOS散热特性研究

针对功率VDMOS真空下壳温显著升高的问题,对安装叉指形散热器的功率VDMOS进行了三维建模和温度场模拟分析,研究了其在大气与真空环境下的散热模型。真空环境下功率为10 W、散热片面积为278.42 cm2时,VDMOS壳温较大气下升高了89.8℃。找出了VDMOS大气及真空下壳温与工作功率及散热器表面积之间存在的关系,并进行了相应实验,利用公式计算出的器件壳温与实验壳温的最大差值,大气下不超过2℃、真空下不超过3℃,皆未超过5%,该公式可以作为功率VDMOS应用及热设计的参考依据。分析了真空环境下,功率VDMOS壳温显著升高的原因,并提出了改善措施。

Study on Transfer Heat Performance of Power VDMOS in the Atmosphere and Vacuum

The three-dimensional(3-D) modeling and simulation of temperature field for power vertical double-diffused metal oxide semiconductor transistors(VDMOS) with staggered-finger heat sink were presented to analyze the thermal dissipation problem in vacuum.The heat conduction model was simulated in atmosphere and vacuum boundary condition respectively and the results indicate that the case temperature of power VDMOS in vacuum is 89.8 ℃ higher than that of the situation in atmosphere with 10 W of power dissipation and 278.42 cm2 of surface area of the heat sink.Based on the simulation,an approximate expression of case temperature in terms of power and surface area of heat sink is proposed.The corresponding measurement results revealed that maximum difference of calculation and experiment are 2 ℃ in atmosphere and 3 ℃ in vacuum respectively,and both of the differences are less than 5%.Therefore,the approximate expression is proved to be a reference of application and thermal management of power VDMOS.Besides,the causes of higher case temperature of power VDMOS in vacuum were studied,and several methods of reducing temperature were proposed.