Ed

I am looking for a general formula that gives a flux loading value for comparison on different PCB sizes and different fluxes. The purpose is actually to try and estimate a solder pallet lifespan. Many factors can reduce the lifespan of the solder pallet material but flux is a major contributor.

For example, spraying 60ml/min as opposed to 30ml/min can reduce the lifespan by 75% if the solid content is high. We have seen two variations of flux, one with 18% solids and one with 3.6% solids. The customer had no problems with the 1.8% solids but severe problems with the 3.6% solids flux. The same flux with 3.6% solids at another customer had no problems because the volume sprayed  was different. of course, the pre-heat, solder bath temperature and conveyor speed also play their part as the solder pallet material must remain above the flux activation temperature.

What I am trying to do is create a system that lets engineers choose the best wave solder pallet material for their application based on their process parameters, production set-up and PCB design. We know that high spray volumes of high solid content flux reduces lifespan and we can work on this simple formula but I would prefer to be a bit more scientific about it.

Kenny Munro
Product Manager
Durostone - solder pallet materials