In electronics, desoldering is the removal of solder and components from a circuit board for troubleshooting, repair, replacement, and salvage. Tools Desoldering tools and materials include the following: Solder wick Heat guns, also called hot air guns Desoldering pump Removal alloys Removal fluxes Heated soldering tweezers Various picks and tweezers for tasks such as pulling at, holding, removing, and scraping components. Vacuum and pressure pumps with specialized heater tips and nozzles Rework stations, used to repair printed circuit board assemblies that fail factory test. Terminology is not totally standardised. Anything with a base unit with provision to maintain a stable temperature, pump air in either direction, etc., is often called a "station" (preceded by rework, soldering, desoldering, hot air); one, or sometimes more, tools may be connected to a station, e.g., a rework station may accommodate a soldering iron and hot air head. A soldering iron with a hollow tip and a spring-, bulb-, or electrically-operated suction pump may be called a . Terms such as "suction pen" may be used; the meaning is usually clear from the context. Pumps Electrically operated pumps are used for several purposes in conjunction with a hand-held head connected by a tube. Suction pumps are used to suck away molten solder, leaving previously joined terminals disconnected. They are primarily used to release through-hole connections from a PCB. The desoldering head must be designed so that the extracted solder does not solidify so as to obstruct it, or enter the pump, and can be removed and discarded easily. It is not possible to remove a multi-pin part by melting solder on the pins sequentially, as one joint will solidify as the next is melted; pumps and solder wick are among methods to remove solder from all joints, leaving the part free to be removed. Suction pumps are also used with a suction head appropriate for each part to pick up and remove tiny surface mount devices once solder has melted, and to place parts. Hot air pumps blow air hot enough to melt all the solder around a small surface mounted part, and can be used for soldering parts in place, and for desoldering followed by removal before the solder solidifies by a vacuum pump or with tweezers. Hot air has a tendency to oxidise metals; a non-oxidising gas, usually nitrogen, can be used instead of air, at increased cost of equipment and consumables. Desoldering