Analysis of Temperature Field During Vacuum Brazing for Plate-Fin Heat Sinks

To address the issue of uneven temperature distribution during the vacuum brazing of plate-fin aluminum alloy heat sinks, the equivalent thermophysical parameters were derived by the equivalent homogenization method, and an overall equivalent heat transfer model for the heat sink was established. The reliability of the model in simulating the temperature field during vacuum brazing was validated through vacuum brazing tests, and the temperature distribution of the heat sink during the brazing process was investigated. A local plate-fin simulation model was developed to analyze the influence of fin structure on the temperature and stress fields. The results show that the temperatures of the heat sink during the brazing process obtained by simulation with the equivalent heat transfer model, agreed well with the test values. The absolute errors of the temperature of heat sink during the heating phase of the third brazing stage were all within 5 ℃, which validated the reliability of the model. Based on the equivalent heat transfer model simulations, the overall temperature of the heat sink was found to be symmetrically distributed along the y- and z-directions, but shifted along the x-direction due to the "heating" effect of the central sealing strips. Based on the local plate-fin simulation model, the simulated temperature distribution in type B curved fins was more uniform compared to that in type A straight fins, but the thermal stress was higher. Extending the holding time could improve the uniformity of the temperature field; however, it also led to an increase in thermal stress due to the expansion of high-temperature regions.