Difference between revisions of "Soldering iron"

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A soldering iron is a hand tool most commonly used in soldering. It supplies heat to melt the solder so that it can flow into the joint between two workpieces.

A soldering iron is composed of a heated metal tip and an insulated handle. Heating is often achieved electrically, by passing an electric current (supplied through an electrical cord or battery cables) through the resistive material of a heating element. Another heating method includes combustion of a suitable gas, which can either be delivered through a tank mounted on the iron (flameless), or through an external flame.

Less common uses include pyrography (burning designs into wood) and plastic welding.

Soldering irons are most often used for installation, repairs, and limited production work. High-volume production lines use other soldering methods.^[1]

Types

Electronics

For electrical work, a low-power iron, a power rating between 15 and 30 watts, is used. Higher ratings are available, but do not run hotter; instead there is more power available for larger joints.^[2]

Small battery-operated or gas soldering irons are useful when electricity is unavailable.

Temperature-controlled soldering station

A temperature-controlled soldering station consists of an electrical power supply and a soldering iron. It is most commonly used for soldering electronic components.

A variety of means are used to control temperature. The simplest of these is a variable power control, much like a light dimmer, which together with the loss of heat from the iron to the environment roughly sets the temperature. Another type of system uses a thermostat, often inside the iron's tip, which switches power on and off to the elements. A more advanced version of this uses a microprocessor to monitor the temperature of the tip via a thermocouple and adjusts the power to the heating element accordingly.^[2]

Another approach is to use magnetized soldering tips which lose their magnetic properties at a certain temperature (the Curie point). As long as the tip is magnetic, it clings to the heating element. At the design temperature, it loses contact, cooling down. Other complex irons circulate a high-frequency AC current through the tip, using magnetic physics to direct heating only where the surface of the tip drops below the Curie point.

Stands

A soldering iron stand keeps the iron away from flammable materials, and often also comes with a cellulose sponge and flux pot for cleaning the tip. Some soldering irons for continuous and professional use come as part of a soldering station, which allows the exact temperature of the tip to be adjusted, kept constant, and sometimes displayed.

Tips

Some soldering irons have interchangeable tips, also known as bits, that vary in size and shape for different types of work.^[2] Pyramid tips with a triangular flat face and chisel tips with a wide flat face are useful for soldering sheet metal. Fine conical or tapered chisel tips are typically used for electronics work.

Older and very cheap irons typically use a bare copper tip, which is shaped with a file or sandpaper. This dissolves gradually into the solder, suffering pitting and erosion of the shape. Copper tips are sometimes filed when worn down. Iron-plated copper tips have become increasingly popular since the 1980s. Because iron is not readily dissolved by molten solder, the plated tip is more durable than a bare copper one. This is especially important when working at the higher temperatures needed for modern lead-free solders. Solid iron and steel tips are seldom used because they store less heat, and rusting can break the heating element.

Cleaning

When burnt flux and oxidized material begin to accumulate on the tip, they can block heat transfer and contaminate joints, making soldering difficult or impossible. Therefore, the tips are periodically cleaned. Many soldering stations come with cellulose sponges which are dampened and used to wipe a hot iron's tip clean. A wire brush, preferably brass or wire wheel (mounted on a bench grinder), is sometimes carefully used to remove very severe oxidation, though this may risk damaging the tip's protective iron plating. A small amount of fresh solder is usually then applied to the clean tip in a process called tinning. The working surface of the tip is usually kept tinned (coated with wet solder) to minimize oxidation. Oxidation blocks heat transfer, corrodes the tip, and contaminates the joint.

See also

• Soldering gun
• Brazing — Joining metals structurally by the use of a higher temperature joining alloy than solder.
• Welding — Melting two objects to be joined into each other.
• ColdHeat — A simple "instant heat" soldering iron

References

de:Lötkolben fr:Fer à souder ko:납땜인두 it:Saldatore (attrezzo) he:מלחם kk:Дәнекерлегіш lt:Lituoklis nl:Soldeerbout ja:はんだごて no:Loddebolt nn:Loddebolt pl:Lutownica ru:Паяльник simple:Soldering iron szl:Lutkolba fi:Juotin sv:Lödkolv tl:Plantsang panghinang tr:Havya

1. ↑ Bralla, James G. Handbook of Manufacturing Processes - How Products, Components and Materials are Made Industrial Press, 2007 page 297
2. ↑ ^{2.0 2.1 2.2} Winstanley, Alan, The Basic Soldering Guide, archived from the original on 2010-04-14, retrieved 2010-04-14.