Desoldering-Technique-Surface mount-Custom

Design Circuit Board Pcb

Technique

Surface mount

If they do not need to be re-used, some surface-mount components can be removed by cutting their leads and desoldering the remnants with a soldering iron.

If they may not be destroyed, surface-mount components must be removed by heating the entire component to a temperature sufficient to melt the solder used, but not high or prolonged enough to damage the component. For most purposes a temperature not exceeding 260 °C (500 °F) for a time not exceeding 10 seconds is acceptable.

The entire board may be preheated to a temperature that all components can withstand indefinitely. Then localised heat is applied to the component to remove, with less heating required than from cold. The most usual tool is a hot air (or hot gas) gun with a nozzle of appropriate size and shape to heat the component, with nearby components shielded from the heat if necessary, followed by removal with tweezers or a vacuum tool. Removal of multi-pin components with a soldering iron and solder removal tools is impractical, as the solder between the component and the pads remains in place, unlike solder which can be removed from a hole.

Hot air (or gas) may be applied with tools ranging from some portable gas soldering irons such as the Weller Portasol Professional which can be fitted with a narrow hot-air nozzle, set to a temperature not controlled but approximately correct, to an industrial rework station with many facilities including hot-gas blowing, vacuum part holding, soldering iron head, and nozzles and fitting specific to particular component packages.