REFLOW PROCESS OPTIMIZATION OF TINNED COPPER STRIP BASED ON FSI-THERMAL SIMULATION

The reflow process of tinned copper (TC) strips is critical for meeting the high metal surface quality standards in electronic devices. A significant challenge is obtaining high-quality reflow-derived tinned copper (R-TC) through the remelting of the tin layer. The fluid-solid thermal (FSI-Thermal) coupling in this process is crucial for tin plating quality. This study proposes an effective method to address local yellowing on the R-TC surface by developing an FSI-Thermal model and optimizing the reflow process. At the feed rate of 0.1 m/s, heat flow of 925 K, and inlet velocity of 10 m/s, the force borne on the TC surface is even, and the minimum temperature approaches 532.4 K (> 505.05 K), accompanied by the thermal stress-induced deformation. However, the TC surface temperature is distributed unevenly in the external chamber. Reflow test is performed based on simulated parameters. Results show that due to the thickness difference of surface oxides, local yellowing takes place on the R-TC surface, and the optimized reflow process substantially reduces the nonuniformity of the tinned oxide layer and realizes the high-quality sedimentation of the clad layer. (Received in October 2024, accepted in February 2025. This paper was with the authors 3 weeks for 2 revisions.)