Look what kind of soldering flux you use. There are many soldering fluxes, so it's better to avoid cleaning flux.Another possibility is that the flux used in your appliance contains rosin and halogen, so that when you encounter moisture, it will become acid and corrode the board, so it will leak.I'm new here too. Maybe not all right. Show off.
You mean after welding? Is usually caused by excessive flux residue on the circuit board.
The main reason is that the formula of the flux is unreasonable, and the content of organic acids and halogens is over standard, which leads to the decrease of the insulating impedance of the residue and leakage of electricity.
