Printed circuit boards or PCBs as they are commonly known are basically the boards inside electronic appliances that hold components in place and have tracks that conduct electrical power throughout the board. When soldering on PCBs, various rules of soldering may fail due to the small size and sensitivity of the components. Here are a few dos and don’ts of soldering on PCBs.
Do not use huge tools
Tools such as heat guns basically blow hot air into the printed circuit board you wish to desolder. However, it is not advisable for desoldering on precise points since it will melt off the solder from the entire circuit board. This method is thus only usable for recovering parts from old and unusable PCBs. Desoldering guns, guns and air pumps should also not be used for any soldering or desoldering work on PCBs.
Turn off live power sources
This helps avoid the danger of electric shock where current travels through the PCB components onto the soldering iron. Switching the power supply off while soldering will also reduce the possibility of the PCB’s component damage. This occurs through short circuits that can be formed through contact with the iron tip.
In soldering, there is the ever present possibility of exposure to lead and rosin, both found within solder. This is shown by the visible fumes present during soldering. These may get into the body through unintentional ingestion via the skin. Both pose serious health hazards and their uses are even regulated in some states and environments. Taking breaks for fresh air away from soldering will do you a lot of good. This is due to the fact that soldering PCBs takes much more concentration and your body is thus much closer to the workbench than in other types of soldering.
Soldering can be done using a variety of tools. These include soldering irons, soldering guns, welding machines, brazing guns and soldering torches. Each of these methods has its advantages and downsides. We start by looking at the upsides to using a soldering iron as compared to the available options.
Soldering irons are to a great extent more precise than their welding and brazing counterparts. This is due to the relatively small size and heat delivery mechanisms employed by a soldering iron. The sharp and relatively narrow tips in soldering irons make them suitable for use in small spaces and for components such as PCBs where other brutal methods such as brazing, torching and welding would not apply.
Most modern day soldering irons come equipped with an inbuilt thermostat. This serves the purpose of regulating the heat output of the iron via an internal mechanism. This makes soldering irons easier and safer to use especially while soldering sensitive items such as PCB components. Other methods such as welding and brazing have very little control if any over the flame produced by the soldering torch or welding equipment. This makes them unsuitable for sensitive tasks.
Prices and costs
Soldering irons tend to be easier to purchase and maintain as compared to other alternative tools. For example, welding equipments are relatively pricier as compared to soldering irons thus making them a less viable alternative. The parts making up soldering irons are also easier to replace thus making them even cheaper in the long run.
General safety and usability
Soldering irons produce less heat as compared to brazing and welding. This implies that they are relatively safer to use since they pose lesser risks of burns to the operator. The flames produced by butane torches can easily cause serious burns.
A desoldering pump is a small piston-like tool essential for the removal of solder from PCBs and other components. A desoldering pump normally has three main elements; the spring mechanism, the tip and the suction mechanism. The working of a desoldering pump is a little bit complicated but doesn’t take long to learn. To use the tool, push the piston handle on top while placing the tip at the solder you want to melt. Hold this in place until the solder melts which may take little to average time. Once the solder melts, press the button on the side of the desoldering pump. This causes the suction mechanism to activate and pull backwards creating a vacuum within the piston. This vacuum effectively pulls with it the molten solder at the base of the tip thus effectively desoldering the component. It’s a relatively complex process and mechanism and takes a while to get used to. However, once you get the hang of it, it has some unique upsides as compared to other options. These include:
As compared to methods such as use of compressed air or a desoldering heat gun, a desoldering pump is very effective in the sense that it focuses only on the exact point that you want to desolder from. This ensures that in printed circuit boards, components that need to remain soldered in place actually remain soldered in place. Blowing a circuit board with a bust of hot air for example decoders all components from the board and in some instances damages some.
Unlike other methods that use a melt and remove mechanism, a desoldering pump makes use of an integrated system that simultaneously melts and pimps off the unwanted solder. This implies that its among the quickest desoldering options available.