1. Disassemble the components on the single-sided printed circuit board: toothbrush method, screen method, needle method, tin absorber, pneumatic suction gun and other methods can be used. Table 1 provides a detailed comparison of these methods.

Most of the simple methods for disassembling electronic components (including foreign advanced pneumatic suction guns) are only suitable for single panel, and the effect of double panel and multi-panel is not good.

2, disassemble the components on the double-sided printed circuit board: single side integral heating method, needle hollowing method, tin flow welding machine can be used. The single integral heating method requires a special heating tool and is inconvenient for general use. Needle hollowing method: First of all, the pins of the components that need to be removed are cut off, and the components are left on the printed circuit board, and then the tin on each pin is melted with a soldering iron, and it is taken out with tweezers, until all the pins are taken, and then the medical needle with the inner diameter of the welding disc hole is holed out, although this method has several processes, However, it has no effect on the printed circuit board, it is convenient to draw materials and simple to operate, and it is extremely easy to achieve, and I believe that it is a more ideal method after years of practice.

3, disassemble the components on the multi-sided printed circuit board: if the above methods are used (in addition to tin flow welding machine), it is not difficult to disassemble, or it is easy to cause the connection between the layers. Generally, the welding pipe foot method is used to cut the components from the root of the components, leave the pins on the printed circuit board, and then weld the new device’s pins on the pins left on the printed circuit board. However, it is not easy to weld multi-pin integrated blocks. The tin flow welder (also known as the secondary welder) solves this problem and is the most advanced tool for disassembling integrated blocks on dual and multilayer printed circuit boards. But the cost is high, need to invest several thousand yuan. Tin flow welding machine is actually a special small wave soldering machine, is to use the tin flow pump to extract fresh and not oxidized molten tin from the tin pot, through the optional different specifications of the spray nozzle, forming a local small wave peak, acting on the bottom of the printed circuit board, the printed road board of the removed components of the pin and the solder hole in 1 to 2 seconds will immediately melt, at this time, The components can be removed lightly, then compressed air is used to blow through the weld holes at the parts of the components, the new components are reinserted, and the finished products are welded on the crest of the spray nozzle.