If you need to turn off your processes for a prolonged period, the following points should be considered:
Soldering equipment with an open flux application (foaming)
Where your equipment has an open fluxing unit it will need to be completely drained and the tank/pipework flushed through with IPA or flux thinners. If left in the tank the alcohol will evaporate off leaving an ever-thickening flux and potentially blocking pipework and pumps (if fitted).
Flux drained out can be returned to the original container (usually attached to the tank for top-up) but the general rule is to dispose of this as waste.
Soldering equipment with a sealed flux application (spraying)
Spray fluxing is the more common application method and used for wave and selective soldering processes. The flux supply container should be removed and resealed and the system will need a thorough flushing through with IPA or flux thinners. Many selective soldering fluxes are water based but IPA remains the most effective method to clean out the pipework and nozzle etc.
Already opened flux containers
Most flux containers once opened have a 3-month shelf-life (please check with your manufacturer). The container should be sealed and stored in a cool environment where it is not subject to extremes of temperature or light (direct sunlight). It is very helpful to ensure you identify when the container was opened, simply indicate a date when first introduced to the shop floor.
Unopened flux containers
New sealed containers typically have a 1-year shelf-life if stored according to the manufacturer’s instruction, cool room, no temperature extremes and out of direct sunlight
Expired shelf-life on your return
If when you return to production, if you find that the container has exceeded the shelf-life recommendations (typically 1 year for unopened or 3 months for opened) then ideally the flux should be disposed of as waste.
There can be some obvious indications that the flux is too old such as discolouration, particles floating at the bottom of the container or indeed that the soldering results are not as good as they should be.
Should you have any questions please do not hesitate to contact us, we are here to help during these unprecedented times.