Establish an accurate model
First, you need to establish an accurate three-dimensional model of the Circuit Board. This includes the detailed modeling of the geometry, size, material properties, and components of the Circuit Board. For the substrate material of the Circuit Board, its thermal expansion coefficient, elastic modulus, and other thermal physical parameters must be accurately input. At the same time, various electronic components must also be modeled according to their actual structure and material properties to ensure that the model can truly reflect the physical structure of the Circuit Board. For example, for some high-power chips, it is necessary to consider the characteristics of their heat dissipation structure and packaging materials in order to more accurately simulate their thermal behavior when the temperature changes. Through accurate modeling, a reliable foundation is provided for subsequent simulation analysis.
Set reasonable boundary conditions
During the simulation process, the setting of boundary conditions is crucial. For temperature cycle conditions, the temperature change range, rate, and number of cycles must be accurately set. At the same time, the heat dissipation boundary conditions of the Circuit Board in actual use must also be considered, such as whether there is a heat dissipation device, the convection heat transfer coefficient of the surrounding environment, etc. For example, if the circuit board is installed in a chassis with air cooling, it is necessary to reasonably set the convection heat transfer boundary conditions according to the structure of the chassis and wind speed and other factors. In addition, for the connection parts between the circuit board and other components, corresponding constraints should be set to simulate the actual installation state, so as to more accurately analyze the thermal stress distribution under temperature cycle.
Select the appropriate simulation algorithm
Different simulation software provides a variety of thermal stress analysis algorithms, and it is necessary to select the appropriate algorithm according to the characteristics and analysis requirements of the circuit board. For complex circuit board structures and nonlinear material properties, the finite element method is a commonly used and effective algorithm. It can discretize the circuit board into multiple small units, perform accurate thermal stress analysis on each unit, and obtain the thermal stress distribution of the entire circuit board by solving the equation group. When selecting a finite element algorithm, it is also necessary to consider the accuracy and convergence of the mesh division, and improve the accuracy of the simulation results by continuously optimizing the mesh quality. In addition, for some circuit boards with special thermal physical phenomena, such as the coupling of heat conduction and thermal radiation, it is also necessary to select an algorithm that can handle multi-physics field coupling.
Result verification and optimization
After completing the simulation analysis, the results need to be verified and optimized. On the one hand, the simulation results can be compared with the actual experimental data. If there is a large deviation, the cause should be analyzed and the model, boundary conditions or algorithm should be adjusted. For example, if the thermal stress concentration area predicted by the simulation is inconsistent with the fault location observed in the experiment, it is necessary to check whether the model is over-simplified or the boundary conditions are set unreasonably. On the other hand, sensitivity analysis can be performed by changing the parameters or boundary conditions of the model to further optimize the simulation model and improve the accuracy of the prediction. Through continuous verification and optimization, the simulation software can more accurately predict the thermal stress distribution of the Circuit Board under different temperature cycles, providing strong support for the design and reliability evaluation of the Circuit Board.