A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two workpieces. A soldering iron is composed of a heated metal tip (the bit) and an insulated handle. Heating is often achieved electrically, by passing an electric current (supplied through an electrical cord or battery cables) through a resistive heating element. Cordless irons can be heated by combustion of gas stored in a small tank, often using a catalytic heater rather than a flame. Simple irons, less commonly used today than in the past, were simply a large copper bit on a handle, heated in a flame. Solder melts at approximately 185 °C (365 °F). Soldering irons are designed to reach a temperature range of 200 to 480 °C (392 to 896 °F). Soldering irons are most often used for installation, repairs, and limited production work in electronics assembly. High-volume production lines use other soldering methods. Large irons may be used for soldering joints in sheet metal objects. Less common uses include pyrography (burning designs into wood) and plastic welding (as an alternative to ultrasonic welding).
History
Before the development of electric soldering irons, the typical soldering iron consisted of a copper block, with an appropriately shaped point, supported on an iron rod and held in a wood handle. Immediately before use, the iron was heated over a fire or in a charcoal brazier, and it had to be reheated whenever it became too cool for use. Soldering irons were primarily used by tinsmiths and coppersmiths to work with thin sheet metal. A large copper block was required in order to have sufficient thermal capacity to provide useful heat after removal from the fire, and copper is expensive. This led to the development of soldering irons that had a small copper tip attached to an inexpensive cast-iron block. Some irons even had removable and replaceable copper tips. The first electric soldering iron had a very lightweight platinum tip heated by electric current flowing through the tip itself. By 1889, electric soldering irons were being developed with a resistance wire wrapped around the back end of the copper head and enclosed in a protective shell. Alternatively, the heating element could be enclosed in a relatively light-weight hollow copper head. In 1894, the American Electrical Heater Company began manufacturing electrical soldering irons on a large scale in Detroit. They started producing them and shortly after American Electrical Heater Company released their line of soldering irons. In 1905, Scientific American Magazine, published a tutorial on making a soldering iron that clearly explains how early irons were made. In 1921, a German company founded by Ernst Sachs developed an electrical soldering iron similar to American Electrical Heater Company iron. in 1926, William Alferink applied for a patent for the first soldering station.
Actual "Form factor" of soldering irons
In 1946, Carl E. Weller applied for a patent for his soldering gun that could heat instantaneously and began production of the "Speedy Iron" in Pennsylvania. It was manufactured through the Weller Manufacturing Company, and this product was the first instantaneous thermal soldering gun. Few years later, they released to the market a soldering iron on with self-adjusting temperature. In 1951, the company WEN Products began manufacturing its own instantaneous soldering iron. After a three years trial Weller won for patent infringement. In 1960 Weller got the patent for the soldering iron "Magnastat", renewed in 1964 and 1971. This iron could control the temperature by using a temperature-sensitive magnetic tip. The "Magnastat" became a best seller and it was included it in the W-TCP soldering station in 1967. In fact, within the patent, as a complementary description, it defines what today has become the "de facto", the redundancy is worth it, "form factor" of the vast majority of current Japanese and Chinese irons: Hakko, Baku, etc... The now-expired patent, which even Weller has stopped using on some models, described an outer tube holding the coated copper tip, clamped with a nut to the handle.
Located at the remote rear end of draw tube 26, and held thereto by peripheral flange 27, is a freely rotatable threaded nut 28 adapted to be threaded about nut receiving stud 29 of cover flange 21 to draw the tip 11 into proper engagement
Types
Simple iron For electrical and electronics work, a low-power iron, a power rating between 15 and 35 watts, is used. Higher ratings are available, but do not run at higher temperature; instead there is more heat available for making soldered connections to things with large thermal capacity, for example, a metal chassis. Some irons are temperature-controlled, running at a fixed temperature in the same way as a soldering station, with higher power available for joints with large heat capacity. Simple irons run at an uncontrolled temperature determined by thermal equilibrium; when heating something large their temperature drops. A variation is the Scope soldering iron, common in Australia, which operates from a low-voltage source such as transformer or battery, and heats in seconds when the user pushes the thumb-guard, which then acts as a heat controller.
Cordless iron Small irons heated by a battery, or by combustion of a gas such as butane in a small self-contained tank, can be used when electricity is unavailable or cordless operation is required. The operating temperature of these irons is not regulated directly; gas irons may change power by adjusting gas flow. Gas-powered irons may have interchangeable tips including different size soldering tips, hot knife for cutting plastics, miniature blow-torch with a hot flame, and small hot air blower for such applications as shrinking heat shrink tubing.
Temperature-controlled soldering iron
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