How to use Icepak for PCB thermal design
Icepak is a thermal modeling software tool that can be used to study local changes in thermal conductivity in circuit boards. In addition to the computational fluid dynamics (CFD) function, the software tool also takes into account the wiring and vias of the circuit board, and then calculates the thermal conductivity distribution on the whole circuit board. This feature makes Icepak very suitable for the following research work.
Original design and model verification:
The common thermal analysis method is to calculate the average value of the effective parallel and normal thermal conductivity of the whole circuit board according to the number, thickness and coverage percentage of the copper layer and the total thickness of the circuit board, and then calculate the thermal conductivity of the circuit board using the average parallel and normal thermal conductivity.
The Icepak model is created according to ECAD file in 1U server application. The routing and via information of the original circuit board is imported into the model.
In order to check the thermal conductivity distribution, the 45 ℃ constant temperature boundary condition can be assigned to the back of the PCB board, and the uniform heat flow boundary condition can be assigned to the top. High temperature represents low thermal conductivity, and low temperature represents high thermal conductivity. It can be seen from the figure that the temperature is higher in the area without wiring and lower in the area with more wiring. In the area with large vias, the temperature is close to 45 ℃.
This shows that the thermal conductivity distribution is consistent with the wiring distribution in the original design. In order to obtain the local effect of small holes, a smaller background grid size should be used.When the simulation results of the maximum temperature of each key element group are compared with the test results, we find that they have good consistency.
The PCB design has a relatively large wiring coverage, which is designed to increase the heat dissipation in the circuit board and thus reduce the voltage regulator temperature. However, in some cases, in order to reduce the cost, it is necessary to reduce the wiring coverage and not use a heat sink. Therefore, the wiring will be modified, and then the verification model will be used to predict the temperature of the regulator.
