If you need to turn off your processes for a prolonged period, the following points should be considered:
Already opened jars/cartridges
In general, once a new jar of solder paste has been opened the manufacture tends to provides a maximum of 1 month’s shelf-life before recommending the paste is disposed of as waste (please check with you manufacturer for exact shelf life).
If you are removing used paste from a stencil it should never be returned to the original jar and if you are not using it again until after your close-down period, disposal of this paste would be recommended.
Most manufacturers recommend storing new, unopened jars in a fridge or cooling cabinet (between 0 to 10 °C). You need to follow your manufacturers storage instructions to ensure you obtain the full shelf-life of the product. The shelf-life will often be different for smaller containers such as syringes.
There will be a date code or shelf-life expiry date on your container for your reference.
Please note that cartridges can be stored vertically or horizontally. If you store yours horizontally (on their sides) they should ideally be rotated regularly during storage. You will need to take this into consideration when you return to production as flux may have separated if left in one position for too long, which will mean you will need to perform extra kneading strokes on the stencil before printing.
Expired shelf-life on your return
If when you return to production, you find solder paste which has passed its expiry date you will most likely find it will work perfectly well and cause no issues (please check with your manufacturer before doing so). This is however subject to the containers being stored correctly, as per the manufacturer’s instructions.
For our Koki customers we can offer a service to re-validate the paste and ensure that it is still within the manufacturer’s specifications and therefore safe to use.
Should you have any questions please do not hesitate to contact us, we are here to help during these unprecedented times.