Soldering gun
A soldering gun is a tool for soldering metals using tin-based solder to achieve a highly conductive contact. The tool uses a pistol shape, and has a trigger style switch so it can be easily operated with one hand. The body of the tool contains a transformer with a single-turn secondary element. A soldering tip, made of a loop of copper wire, is secured to the end of the transformer secondary by screws. When the primary of the transformer is energized, the secondary produces a fraction of a volt and several hundred amperes of current, which rapidly heats the copper tip. Since the tip has a much smaller cross section than the rest of the tubular copper winding, most of the heat is produced near the point of use. A tap on the primary winding is often used to light a pilot lamp which also provides illumination of the workpiece.
Applications such as soldering high current load wires, often found in inconvenient locations such as automobile bodies, preclude the use of a soldering station. A constant-heat device has to be set in a safe place when not in use, to prevent damage or fire. The fast switching gun cools quickly enough to be set down just seconds after use.
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[edit] Applications
Soldering guns are used where more heat is needed than from pencil-style soldering irons. They can be used for heavy electrical connections, stained glass assembly, and light sheet-metal work. Typical soldering guns are rated between 100 and 240 watts power. A gun may include a two-stage trigger to give two heat settings. Consumer soldering guns are often packaged with accessory tips intended for cutting and shaping plastic.
Soldering guns may be used to solder the small SMD components, after replacing the default thick wire with a thin one. If the wire loop is bent into a rectangular shape, the gun can be used to solder 14- and 16-pin 1.27 mm pitch SMD packages in about 8 seconds by heating all pins at once.
The tip shape, in the form of a wire loop, is advantageous for getting into confined space; the tip can be rotated to get into a gap between neighbouring components. This is not practical with the cone shape of a usual soldering iron. Temperature in the soldering gun is regulated manually by holding the button until the solder melts, and then releasing it. When the solder is about to start solidifying, the button is pressed again, and so on. An experienced worker develops the skill to regulate the temperature according to need.
A disadvantage of a soldering gun is that the copper wire loop slowly dissolves in the solder and has to be regularly replaced. The soldering gun generates an electromagnetic spike when the button is released, which can be a problem for electromagnetically-sensitive devices. The spike can be seen when a high-efficiency LED is soldered, as the LED flashes. Soldering guns produce too much heat for joints on printed circuit boards. The heavy magnetic field produced by the tip can attract and hold small ferrous metal pieces (screws, etc.).
[edit] History
Pistol-grip electrically-heated soldering tools had been used since the 1920s. In 1941 Carl E. Weller invented and later obtained U.S. Patent 2,405,866[1] for a transformer-type soldering tool, which heated up rapidly.[2] Unlike other electrically-heated tools of the time, his soldering gun used a copper heating element, directly heated by a current of hundreds of amperes produced from a small transformer in the body of the gun. The relatively small mass of the copper element heated rapidly and cooled off quickly when the trigger was released. Weller formed a company to manufacture and sell his invention commercially in 1946. The Weller company was bought in 1970 and merged into the Cooper Industries group.[3]
[edit] See also
[edit] References
- ^ Weller, Carl E., "Electrical Heating Apparatus" US 2405866, filed July 14, 1941, issued August 1946.
- ^ Luckett, Hubert (May 1963). "Have Gun Will Solder". Popular Science Magazine 182 (5): pp. 163–165, 191. ISSN 0161-7370. http://books.google.ca/books?id=uSADAAAAMBAJ&pg=PA163.
- ^ http://www.fundinguniverse.com/company-histories/Cooper-Cameron-Corporation-Company-History.html retrieved 2009 Oct 19
