Li Hai-yuan, Li Bao-ming
National Key Laboratory on Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2002 Jun;22(3):381-3.
Thermal deformation can be caused by high partial heat flux and greatly reduce thermal reliability of electronic devices. In this paper, an attempt is made to measure the thermal deformation of high power electronic devices under working condition using laser holographic interferometry with double exposure. Laser holographic interferometry is an untouched measurement with measurement precision up to micron dimension. The electronic device chosen for measurement is a type of solid state relay which is used for ignition of rockets. The output circuit of the solid state relay is made up of a MOSFET chip and the power density of the chip can reach high value. In particular situations thermal deformation and stress may significantly influence working performance of the solid state relay. The bulk deformation of the chip and its mount is estimated by number of interferential stripes on chip surface. While thermal stress and deformation can be estimated by curvature of interferential stripes on chip surface. Experimental results indicate that there are more interferential stripes on chip surface and greater flexural degree of stripes under high power. Therefore, these results reflect large out-of-plain displacement and deformed size of the chip with the increase of load current.
热变形可能由高局部热通量引起，并会大大降低电子设备的热可靠性。本文尝试采用双曝光激光全息干涉测量法来测量大功率电子设备在工作状态下的热变形。激光全息干涉测量法是一种非接触式测量方法，测量精度可达微米级。所选择用于测量的电子设备是一种用于火箭点火的固态继电器。固态继电器的输出电路由一个MOSFET芯片组成，芯片的功率密度可达到很高的值。在特定情况下，热变形和应力可能会显著影响固态继电器的工作性能。芯片及其安装座的整体变形通过芯片表面干涉条纹的数量来估算。而热应力和变形则可通过芯片表面干涉条纹的曲率来估算。实验结果表明，在高功率下芯片表面有更多的干涉条纹，条纹的弯曲程度更大。因此，这些结果反映出随着负载电流的增加，芯片的面外位移和变形尺寸增大。
