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Soldering Techniques for Electronics
The Soldering Iron
- The most important tool in electronics soldering at home is the soldering iron. Soldering irons come in a range of specifications and features. The iron you select should be suited to the electronics being soldered. Inexpensive soldering irons come in a range of wattages. The power of the iron doesn't necessarily indicate a hotter iron. Wattage indicates that the iron cools down more slowly and is able to handle larger solder joints.
More expensive soldering irons have a temperature control feature that allows the iron to be set to higher and lower heats. This can be useful when soldering delicate, temperature-sensitive electronics. Temperature-controlled soldering irons are generally more expensive and are attached to a base where the controls are housed.
Whether you are using a less expensive hobbyist iron or a temperature-controlled iron, it is important to match the iron to the soldering task. If you are soldering large joints, be sure to use an iron that is able to heat the entire joint equally.
- There are many types of solder, but most are grouped into two types: One with the flux either mixed with the solder or in the core of the solder and solder that requires the application of flux. Flux is a wetting agent that helps the solder bond to the area where the component joins the circuit board or wire. Even with solders with flux cores, adding additional flux can help ensure a solid joint.
- The first step in creating a solid solder joint is to heat the component and the wire or circuit board. As the joint is heating, apply a flux-core solder to either the wire of the component or solder pad on the circuit board. As the components heat, the solder and flux will melt, causing them to flow. The transition from solid to liquid is very quick, so be careful not to apply too much solder. Once the pad and component are covered, leave the soldering iron on the joint for several seconds to ensure proper melting of the solder. The melted solder will have a silvery liquid look when properly melted that will cool to a grayer, more matte finish.
- If you are replacing a defective component, the first step may be to remove the old component. A couple of tools can help with this. The easiest to use is solder wick. Solder wick is braided copper wires that will wick the solder away from the old joint and allow for its easy removal. To use a solder wick, place the wick on the joint to be de-soldered and wait for the heat to melt the underlying solder. The wick should turn silver as the solder is removed from the joint. Do this until enough solder is removed and the component separates from the circuit board.
The second de-soldering device is a pump. This technique requires two hands. First, heat the solder to ensure it is melted and activate the pump to remove the liquid metal from the solder joint.