Soldering Irons: Pro'sKit
Types and Working Principles of Soldering Irons
Soldering, the process of joining two metal parts by melting a metal with lower melting point (solder) and putting it into the joint between the work pieces, is an extremely important technique with many appliances in electronics, plumbing and various types of metalwork. Soldering is in the core of each of those industries and it would be difficult to imagine any of them without it.
There is a variety of different tools that may be used for soldering, such as soldering guns, soldering torches, soldering coppers, etc. In theory, each of those tools can be used for any type of soldering, though in practice some are more suitable than others in each case.
Perhaps the most common and widely used type of soldering tool is a soldering iron, most often encountered in electronics repair and installation. Both the construction and the working principle of a typical model are quite simple. The device consists of two main parts: an insulated handle and a heating element made of a highly resistant metal. Current passes through the heating element, which in turn generates heat (because of its high resistance). This heat is then used to melt the solder and put it between the work pieces to join them together.
There are several types of these soldering tools:
- Simple soldering iron
- Cordless soldering iron
- Temperature-controlled soldering
- Soldering station
- Soldering tweezers
Simple iron. The description of this type is in its name. This is the simplest type of soldering tool, consisting only of a heating element and an insulated handle. Most commonly used in basic electronics repair, these devices typically have uncontrolled temperature (their maximum temperature being determined by thermal equilibrium) and an average power rating of 25 Watts.
Cordless iron. This type can be divided into two sub-categories itself: battery and gas-powered. Gas-powered soldering irons are more popular, their heating element is heated by burning of a gas (e.g. butane, isobutane) which is stored in a small self-contained tank. Both types have a somewhat limited temperature regulation, with gas-powered ones using gas-flow adjustment to control their power. On the other hand, these soldering irons have their advantages. They usually have interchangeable tips (miniature blow-torch, hot knife, heat shrinkage tip, etc.) that make them quite universal. Also, due to their compact size they are very useful when soldering needs to be done in hard to reach places or in places where electricity is not available.
Temperature-controlled soldering iron. This type of soldering tool is very similar to the simple iron, with an addition of a temperature controlling mechanism. These mechanisms differ depending on the model, the most common and simple of them being the variable power control. Other kinds of temperature controls include:
- Thermostat. Usually placed directly inside the heating element, it automatically switches the power supply on and off.
- Thermal sensor. Combined with the internal circuitry, it constantly measures the temperature of the heating element and adjusts the power to keep the temperature at a desired level.
- Magnetized soldering tips. Perhaps the most curious and advanced mechanism of regulating the temperature. Magnetized soldering tips can lose their magnetic properties at a specific temperature, a Curie point. While they maintain their magnetic properties they close the power supply switch but as soon as their temperature rises and they lose their magnetic properties, the switch opens, the power is no longer supplied to the heating element and the temperature decreases.
Besides an obvious advantage, being able to control the tip temperature, temperature-controlled soldering tools have another, not less important property that their simpler counterparts have, which is being able to solder large connections. Simple irons are not suitable for soldering large pieces of metal as they lose too much power in the process. The ability to steadily maintain the tip temperature at a constant value makes temperature-controlled types suitable for work with both small and large connections.
Soldering station. This type of soldering tool is always temperature controlled. The control mechanism is located on the power supply box, which is also sometimes supplied with a display. These devices usually allow adjusting a wider range of parameters, such as setting the minimum/maximum temperature, storing several preset temperature values, etc. Other parts of a typical soldering station include a stand (for the soldering iron when it is not in use) and a cleaning sponge. Thanks to the ability of combining various functions in a single station makes these soldering tools quite universal.
Soldering tweezers. Usually used for soldering small components with two terminals, like resistors or capacitors, soldering tweezers work as regular tweezers except that they have two heated elements on their arms. Combined with a vacuum pick up tool, these devices are very useful for high precision soldering.
As was mentioned before, there are various types of soldering iron tips. If you have difficulty choosing an iron tip or curious about which type best fits your needs, you can check this article.
Just as with any other equipment, It is very important to keep your iron tips clean. As time goes by, the tip becomes covered with burnt flux and oxide. Once this happens, it becomes very difficult or even impossible to work with due to the fact that the solder no longer sticks to it. To make sure this does not happen, the tip has to be cleaned thoroughly and covered with solder, a process known as tinning.
If you need to buy a soldering iron, it is important to remember that quality of the device is extremely important. Therefore, it is recommended to purchase a more functional model with a little higher price than a cheaper one that will end up costing a lot more in the long run.