DESOLDERING

In electronics, 'desoldering' is the removal of solder and components from a circuit for troubleshooting, repair purposes 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.
Specialized tools, materials, and techniques have been devised to aid in the desoldering process.
Desoldering tools and materials include:

★ Desoldering braids

★ Heat guns

★ Vacuum plungers (solder suckers)

★ Removal alloys

★ Removal fluxes

★ Vacuum and pressure pumps with specialized heater tips and nozzles

★ Rework stations, used to repair printed circuit boards that fail factory test.

Contents

Technique

Technique

Desoldering requires application of heat to the solder joint and removing the molten solder so that the joint may be separated. Desoldering may be required to replace a defective component, to alter an existing circuit, or to salvage high value components for possible re-use. Excess application of heat may damage electronic components, or destroy the bond between a printed circuit trace and the underlaying substrate.
A single joint can usually be quickly undone with a soldering iron and use of either vacuum bulb, plunger, or desoldering braid. Once the solder has been melted, the vacuum device is applied to withdraw solder from the joint by a rapid movement of air. Desoldering braid draws up the molten solder by capillary action; the braid usually contains the same flux as solder.
Multiple-lead devices require special care in removal. For through-hole mounted devices, special soldering bits that facilitate even distribution of heat over all the leads at one time can be used. For factory re-work, a temperature controlled rework station may contain such bits, hot-air systems, and a vacuum system to facilitate removal of the part. Large surface-mounted components require special tooling for production desoldering, although various and improvised methods can be successfully applied for field service. In some instances it is better to destroy the part by cutting off its leads and removing the leads individually, instead of risking damage to the printed circuit board.
Hobbyists may even use a torch or hot air gun to rapidly heat all parts on a board and remove them; such methods are extremely difficult to apply without damaging parts or boards, and may result in toxic fumes.