The SMT ic of this kind of SMT can be welded by general drag welding, but it is more convenient to use a wind gun when disassembling and save tin wire. Drag welding, first align the pad, and then fix a positioning foot, such as welding the first foot, and then press with tweezers, weld the other foot of the diagonal, and then the tin wire under, the soldering iron on the top, welding other pins, do not worry about short circuit, novice exercise to pile a lot of tin, and then use the adhesion of the soldering iron tip or the tip of the knife to stick the excess tin down. It can be tested after careful observation without pin short circuit. # Note a few points 1, the first positioning, tweezer pressure is to prevent the ic on the pcb welding uneven. 2, the welding time should not be too long, plus the drag welding is a lot of tin, more likely to overheat, a failure, wait and try again, to be patient. 3, the quality of the soldering iron flux is related to the control of temperature. 4, the melting point of lead solder wire is not the same as that of lead-free, and the temperature should be mastered. Other packages, such as BGA QFN, can not use drag welding, you need steel mesh positioning tin gun.