The Thermomechanical Analysis Of Microwave Module And Optimization Of Reflow Interface

As the rapid development of SMT (Surface-Mount Technology), highly integrated and narrow spacing microelectronics packaging technology put forward higher requirements to welding process, and traditional experimental ways failed to keep up the development. While simulation way can solve this problem well. By solving finite element model, the temperature field of the weldment and the temperature curve of SMA (Surface-Mount Assemblies) can be generated rapidly and accurately. This make calculating the stress and deformation of module very easy. Therefore, thermal and structural finite element analysis grows its popularity in analyzing temperature curve of SMA, calculating stress and deformation of the weldment and optimizing weldment structure and reflow process parameters.This study focus on the reflow process of LTCC microwave module and following researches are done in order to improve welding quality:1. The heating mechanism of LTCC microwave module in reflow process is analyzed, and the heating environment is converted to boundary conditions and initial conditions by theoretical calculations.2. A thermodynamic simulation model of microwave module is created. Through this model temperature distribution and the temperature curves of module are extracted. Two factors that affect the temperature field are found, they are the order that sections entering a heating zone and the structure of module respectively. And the most uneven temperature distribution appears when the module just entering the cooling zone.3. Through reasonable theoretical simplification, the author calculated the temperature curve of module, and then measured the temperature curve of typical positions on the module (high temperature region, low temperature region and two points on LTCC) by thermocouple. Simulation results matches the theoretical calculations and the measured curves well. The curves obtained by this three methods show the same characteristics:curves of different positions rising successively and all curves having segmentation phenomenon. The deviation of simulation and experimental results is within 8.7%.4. The mechanism of thermal deformation is analyzed. And a structural model is established to calculate the stress and deformation of the module. After analyzing results, the author finds that increasing stiffness of the module can effectively reduce the warp, while the concentration of LTCC’s equivalent stress relieved significant when the fillets increased in reason or external constraints imposed or a suitable interlayer added.5. The original reflow control interface has deficiencies and defects of increasing the users’ cognitive burden. So in order to ensure the quality of reflow soldering and improve efficiency, the reflow monitoring interface is optimized to improve its user experience and friendliness. And it has been proved by eyes movement experiment that the speed participants search and retrieve information has been greatly improved.