Flux is needed to prevent oxidation that tends to form when hot metals come in contact with the air. During printed circuit board repair and soldering, it's common to see liquid flux from the wave soldering equipment poured into jars and applied with an acid brush. That can lead to applying too much flux, forcing an additional cleaning step that might not otherwise be necessary. Other types of flux and special packaging are available that are better suited for PCB repair:
Flux Pen: Flux pens are valved, prefilled pens of flux. Flux pen avoids the mess and hassle involved in filling your own flux bottles. A flux dispensing pen contains the flux in the airtight barrel of the pen. Flux pens are an excellent way to dispense flux for benchtop soldering. You just hold the pen vertically and briefly depress the tip to start the liquid flow. This will saturate the tip of the pen with flux. Draw flux on the area to be soldered. Gently press the tip again when more flux is needed to keep the tip damp with flux.
CircuitWorks flux pens are available with a variety of fluxes to fit your specific shop requirements, including: no-clean, high temperature no-clean for lead-free soldering, rosin, and water soluble.
Tacky Flux: Tacky flux is a viscous, pasty form of flux that is easy to place without it spreading into surrounding areas the way a liquid flux can. It can be used to hold small parts in place before soldering and is common in the manufacture and repair of SMT components. Tacky fluxes in syringe dispensers provide for dispensing convenience similar to a pen in situations where a tacky flux better fits the application. The thick, honey-like consistency is ideal for ball-attach applications, BGA re-balling and hand soldering SMT components. The flux is dispensed from a syringe and can be manually spread over the desired area for soldering.
CircuitWorks No-Clean Tacky Flux is a mildly activated rosin (RMA) no-clean tacky flux. Its formulation includes a unique rosin/resin blend coupled with a proprietary blend of activators and stabilizers, providing significantly increased shelf life and long-term product stability. The remaining residue is stable and can be left on a board without cleaning, or can be easily removed with Flux-Off No-Clean Plus Flux Remover. CircuitWorks Lead-Free Tacky Flux is formulated for higher temperatures common in lead-free soldering.