In electronics, desoldering is the removal of solder and components from a circuit for troubleshooting, for repair purposes, component replacement, and to salvage components. Electronic components are often mounted on a circuit board, and it is usually desirable to avoid damaging the circuit board, surrounding components, and the component being removed.
A desoldering pump, colloquially known as a solder sucker, is a manually-operated device which is used to remove solder from a printed circuit board. There are two types: the plunger style and bulb style. (An electrically-operated pump for this purpose would usually be called a vacuum pump.)
The plunger type has a cylinder with a spring-loaded piston which is pushed down and locks into place. When triggered by pressing a button, the piston springs up, creating suction that sucks the solder off the soldered connection. The bulb type creates suction by squeezing and releasing a rubber bulb.
The pump is applied to a heated solder connection, then operated to suck the solder away.