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Solder flux use when removing circuit board surface parts


Frequently Asked Questions

Fluxes used during electronics reworking have several roles which aid the smooth removal and resoldering of components onto a board, and thus lead to higher yields.

The first of these is heat transfer, especially when soldering irons or other contact heating methods are used. To minimise soldering time, it is important to achieve maximum contact area between tool and joint in order to facilitate rapid heat transfer. This can be achieved by using a relevant shaped tip, solder alloy (through extra tinning), and the flux.

By removing oxides, the flux helps solder flow whilst the component is removed, such that a minimum amount of solder debris is left for cleaning up. The preparation of a desoldered pad for the placement of a fresh component is also aided by flux, in conjunction with either a braid or sucking system.

When soldering a replacement component, flux helps the solder alloy flow (wet) into the joint area, thus forming the joint. This wetting action, in combination with the solder's surface tension, ensures that the joint is filled and that bridged leads do not occur.

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Further information

Some information is only available to TWI Industrial Members. Best practice guides for the electronics and electrical industries:

Soldering - processes
Soldering - process control
Soldering - materials and design


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