Thermal Analysis of Electronic Packages

• Main Authors: Yow-Yi Hsieh, 謝佑宜
• Other Authors: Chia-Lung Chang
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/36165595147607746528

碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 91 === The thesis describes the thermal analysis of electronic packages. CFD software ANSYS/FLOTRAN is performed to simulate the thermal convective effect. Thermal analysis model of small area plate (horizontal and vertical) with surrounding air is built by CFD. Mesh size of air is referred to the thermal boundary layer thickness. Changing the mesh size to predict convection coefficients, compared with theoretical values of small area plate, it is found that reasonable mesh divisions can get the accurate simulations. Also the CFD model could predict reasonable convection coefficients. The convection coefficients of flat plate is set on the surface of FEM model of electronic packages of LQFP208L, PBGA436 and QFN48. Then the thermal resistance is predicted by FEM simulation and compared with the thermal resistance measured by experiments. It is found that the convection coefficients from flat plate can be applied to the FEM model of packages. CFD thermal-fluid analysis is also performed to predict the temperature distribution and convection coefficients of packages. Then the convection coefficients by CFD simulation are set on FEM model of packages to carry out FEM simulations. The thermal resistance by the simulation is compared with experimental values to verify the results. The reasonable convection coefficients in the FEM thermal simulation can predict accurate thermal resistance. The CFD thermal-fluid analysis of packages does not need to set the convection coefficients on the package surfaces, but the model needs more number of elements. Furthermore, the thermal performance of LQFP with heat spreader is studied. The thickness, area, and thermal conductivity of heat spreader are chosen as design parameters to discuss the effect of parameters on the thermal performance. The results are compared with the thermal performance of QFN.