Desoldering pump
A desoldering (also Lotsaugpumpe or Entlötsaugpumpe ) is used for aspiration of liquefied solder (solder) when dissolving a solder bond .
Manually operated desoldering pumps
If an electrical or electronic component is soldered to a circuit board by more than one single solder point , all solder points would have to be melted at the same time in order to remove the component. This is generally not possible - also to protect the component - which is why the tin must be successively removed from all solder points. In the simpler case, the liquid solder can either be sucked up with a desoldering braid or a desoldering pump.
A desoldering pump has a heat-resistant plastic tip, for example made of Teflon , to which the liquid solder does not stick. A negative pressure is generated in the pump, which sucks in the air and the liquid solder. A tip with a small opening would allow more precise work and a longer suction effect, but the free diameter of the tip must have a sufficiently large diameter so that, on the one hand, the tin in the tip does not cool down and clog it. On the other hand, the diameter must allow a sufficiently strong air flow that is able to "carry away" the liquid tin.
Simple manual desoldering pumps generally consist of a cylinder and a piston that is preloaded with a helical spring . Pressing a button releases the spring and the receding piston creates an area of strong negative pressure into which the air flows in from outside. Slightly higher quality pumps of this type have a mechanism that compensates for the recoil that occurs . So the tip does not hit the solder joint.
Electrically operated desoldering devices
In the professional sector there are electric desoldering pumps that have an electrically heated desoldering tip and a vacuum system. These devices are either connected to a central vacuum supply or generate the negative pressure with a motor-driven vacuum pump. There are also systems that are connected to compressed air and generate the required negative pressure via an integrated Venturi nozzle . The desoldering nozzle is made of a metal material. It transfers the heat for melting the solder to the solder joint. It is important to ensure that the transferring surface of the desoldering nozzle accepts the solder well for better heat transfer. The suction of the liquid solder is usually triggered by a hand button on the desoldering device or by a foot switch.
Cleaning of desoldering equipment
With manual pumps, the sucked up solder is collected in the working space of the cylinder and is usually expelled again by re-tensioning the desoldering pump. After a long period of use, the solder residue must be removed from the opened device.
In heatable industrial desoldering devices there is usually a soldering vessel (for example in the form of a glass tube) after the nozzle, into which the liquid solder is sucked and cools there. The solder must be removed, filters replaced and the desoldering device cleaned at regular intervals.
literature
- Reinard J. Klein Wassink: Soft soldering in electronics . 2nd Edition. Eugen G. Leuze, Saulgau 1991, ISBN 3-87480-066-0 .
- Wolfgang Scheel (Hrsg.): Assembly technology of electronics . Verlag Technik et al., Berlin et al. 1997, ISBN 3-341-01100-5 .
