Chris Byrne asked: >Presently we are seeing accurrances of solder splashes in our wave solder >process. We have PCB's that are less then three months old and our storage >process is inside of a ziplock bag with desiccant. Our present environment >has a higher than normal humidity level of 40 to 50%. We have attempted >many adjustments to the proces such as speed, flux gravity(foamer), etc.. >The only thing that appears to eliminate or reduce the splashes is baking >the assembly for 1 hour at 50 degrees 'C' and doing the wave process while >the assembly is still hot. > >Does anyone out there have any ideas of what could cause this problem or >things we should try that could eliminate them? Your "solder splash" problem lacks details, but I'll guess anyway... [(?) means my S.W.A.G.] You are using a water soluble flux (?) Your problem is reduced by reducing the flux vehicle (solvent) by way of having the board "hot" as it enters the fluxer (?) I would suggest that you determine whether your flux vehicle has any water in it. If you have a foam fluxer, you will probably have a flux which is largely IPA. Your IPA can absorb water vapor from the air. If this is so, the water content of the thinned flux will bias your S.G. reading (water has a higher S.G.) and will also make it much more difficult for your preheaters to evaporate the carrier. This is based on the guess that the "splashing" is due to explosive evaporation of liquid hitting the wave. Do you hear any "spattering" sound when the boards hit the wave? IMO, if you do, you instantly know there is a problem! Make sure you are getting good flux solvent (or IPA) and that the flux is changed often enough to avoid picking up a few percent water from the ambient air. You may have gotten a bad batch of IPA or flux, too. Get technical grade or better, and you might consider having a batch of flux and/or solvent analyzed for water content and dissolved or suspended solids. In my experience, solder will tend to stick to contaminants on the board surface, and I have seen such contaminants dissolved in flux before. Also, in the past I found that when a board is very much above room temperature, it would collapse the foam fluxer head (watch under the board as it hits the fluxer to see if the foam is maintaining its surface tension) and we would therefore let all prebaked boards cool back to room temp before going into the wavesolder machine. When we did not, the fluxer head would collapse and patches of the boards were getting little or no flux. Interesting this is NOT what you are doing, and it seems to _help_ you... regards, Jerry Cupples Interphase Corporation Dallas, TX USA http://www.iphase.com/