Abstract: Aiming at the problem of reflow soldering voids in the home appliance industry, using ANSYS software to simulate the process and difference of bubble escape under different air pressures. The study found that the escape of bubbles in the molten tin liquid is divided into two stages. In the first stage, the bubbles are subjected to inertial forces, and the tin liquid moves downward until the entire system is balanced. In the second stage, the bubbles are affected by the surface tension of the tin liquid , Escape outwards until the bubbles overflow; as the air pressure increases, the longer the time required for the bubbles to escape, the two have a nonlinear relationship, so adjusting the air pressure can effectively reduce the occurrence of voids. Through the design experiment, the vacuum welding experiment was carried out using 6 kinds of air pressure environments, and the welding points were detected by X-ray. The smaller the welding air pressure, the smaller the cavity size, which has the effect of suppressing the occurrence of cavity.

Key words: Home appliance controller, Reflow soldering, Welding cavity, ANSYS simulation