PCB Fabrication

Removing components on single-sided printed circuit board

by:A-TECH      2020-04-22
A simple method for removing most electronic components (Including foreign advanced pneumatic suction guns) They are only suitable for single-panel and have poor effect on double-panel and multi-panel. 2. Disassembling components on double-sided printed circuit boards: unilateral integral heating method, needle tube hollowing method and tin flow welding machine can be adopted. The single-connected integral heating method requires special heating tools, which is inconvenient to use. Needle hollowing method: first, cut each pin of the component to be disassembled and remove the component. At this time, what remains on the printed circuit board is the pin whose component has been cut, then use a soldering iron to melt the tin on each pin, take it out with tweezers until all the pins are taken, and then use a medical needle that is suitable for the inner diameter of the pad hole to empty it, although this method has several processes, it has no influence on the printed circuit board. It is convenient to obtain materials, simple to operate and extremely easy to realize. After years of practice, I think it is an ideal method. 3. Disassemble the components on the multi-sided printed circuit board: If the above methods (Tin removal flow welder) It is not difficult to disassemble, or it is easy to cause the connection between layers. Generally, the welded pipe method is adopted to cut the components from the root of the pins of the components, leaving the pins on the printed circuit board, and then welding the pins of the new components on the pins left on the printed circuit board. However, it is not easy to weld multi-legged integrated blocks. Tin flow welder (Also known as secondary welding machine) To solve this problem, it is the most advanced tool to disassemble the integrated blocks on double and multi-layer printed circuit boards. However, the cost is relatively high and it needs to invest several thousand yuan. The tin flow welder is actually a special small wave soldering machine, which uses a tin flow pump to extract fresh and unoxidized molten tin from the tin pot, after the tin spray ports of different specifications are selected, a local small wave peak is formed, which acts on the bottom of the printed circuit board, and the pins of the components to be removed on the printed circuit board and the solder of the welding holes are at 1 ~ It will melt immediately within 2 seconds. At this time, the component can be lightly drawn out, then the welding hole of the component can be blown through with compressed air, and a new component can be reinserted, then weld the finished product on the peak of the tin spray port. Of course, in addition to the above, there are other methods (For example: Copper wire method, alcohol lamp method, etc) However, because it has no outstanding characteristics, it is similar to the method described above, so we will not talk about it here. In daily life, most of the household appliances we use are single-panel. Although various simple methods have their own characteristics, it is recommended to use a tin absorber. For double and multi-panel, the simple method mentioned above can be adopted, and it is better to adopt Tin flow welder with economic permission. You may have encountered a problem all the time, that is, the disassembly of multi-leg components on the double-sided PCB! (Of components need to be removed) In the personal welding exploration, it was found that the hot air gun is very useful for disassembling the IC with double-panel. The method is specially introduced as follows. The tools used for disassembling the IC with 16-pin DIP package are: hot air gun and pliers, parts to be removed :(16-leg IC in the figure) First, clamp the two ends of the IC with pliers: Open the hot air gun, adjust the temperature to 380 degrees, and adjust the wind force to the 80% position, and rotate and evenly heat the IC feet on the reverse side of the PCB! Uniform heating is carried out according to the above method. It is expected that after heating for 10 seconds, the pliers will be quickly pulled out. In general, IC will be unscathed! In this way, the disassembly of the whole IC was completed, but when I looked at the IC hole of the double-sided board where the IC was removed, it was also very large. When I was just about to use a small electric drill to drill the hole on the PCB, inadvertently glanced at the hot air gun, an idea suddenly came into being: hit the biggest wind blowing IC foot hole on the double-sided PCB! It's simply too effective! The entire hole is completely empty! The entire IC is very easy to replace!
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