微加热器热传导试验与计算

Experiment and thermal calculation of micro heater

为了研究微加热膜下方的结构与微加热器性能的关系,利用数值计算与有限元仿真,研究了微加热膜下方空气隙厚度的变化对加热器性能的影响。首先,通过微加热器试验确定了对流换热系数等关键热学计算参数,建立了一维Fourier导热微分方程组,计算了Biot数并以此为依据对模型进行了薄壁简化,使用有限差分法对微分方程进行了数值计算。然后,使用ANSYS有限元分析软件对模型进行了电热耦合仿真,并对在对流换热边界下硅衬底(无空气隙),100,200,300,400μm气隙以及加热膜(完全贯通)6种模型的瞬态温度响应及稳态热分布的结果进行了对比。计算结果表明,相比硅衬底,目前的微加热膜结构在同样边界条件下可以将最高温度提高约17%。空气隙为200μm时,在+5 V驱动电压和空气对流边界条件下,微加热器可以达到390 K,稳态功耗为134 mW,起到了改善最高温度性能,降低功耗的作用。

By utilizing the numerical solution and Finite Element Analysis （FEA） approach, the effect of the air gap beneath a heating membrane on the performemce of a micro heater was calculated and simulated. The thermal convection coefficient was acquired from a heating experiment. Then, a 1D Fourier heat transfer equation was derived. By using the Biot number calculated and the lumped-capac- ity solution, the model was simplified into a multi-layer thin slab one. Furthermore,the transient temperature response and stable thermal distribution of the air gap in thickness of 0 （pure Si substrate）, 100, 200, 300, 400 um and completely through （heating membrane） were compared under the conditions of heat convection and heat transfer. Calculation results show the climax temperature has increased approximately 17% by utilizing the heating membrane structure. The results of steady state and transient thermal-electrical coupled field FEA reveal that 200um air gap structure indeed enhances the climax temperature to 390 K and reduces the power consumption to 134 mW, which is coherent with the numerical calculation results and experiences.