The main disassembly recommendation for high needle density components in SMT processing is the heat gun, which holds the component with tweezers, sweeps all pins back and forth with the heat gun, and lifts the component when melting. If the parts need to be removed, do not blow to the center of the part, the time should be as short as possible. After removing the parts, clean the gasket with a soldering iron.
1. For SMT components with fewer feet, such as resistors, capacitors, bipolar and triodes, tin plating is carried out on a solder plate on the PCB board first, and then the components are clamped on the installation position with tweezers on the left hand and fixed on the circuit board, while the pins on the solder plate are welded on the solder plate on the right hand. The tweezers in the left hand can be loosened and the remaining foot can be welded with tin wire instead. This part is also easy to remove, as long as both ends of the part and the soldering iron are heated at the same time, and the tin is melted and gently lifted to remove.
2. A similar method is used for chip parts with large number of needles and wide spacing. First, tin is plated on the pad, then the element is clamped on the left side with tweezers to solder one foot, and then the other foot with tin wire. It is often better to remove these parts with a heat gun. On the other hand, a hand-held heat gun melts the solder. On the other hand, a fixture such as tweezers is used to remove the parts while the solder melts.
3. For parts with high sales density, the welding technique is similar. First, weld the feet and weld the remaining feet with a wire. The number of feet is large and dense, and the alignment of nails and pads is important. Usually, the pads on the corners are plated with a small amount of tin, and the parts are aligned with the pads using tweezers or hands. The edges of the sale are aligned. The parts are pressed slightly against the printed circuit board, and the pins on the pad are soldered with a soldering iron.
