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Spray fluxing VOC free, as operation HOURS before wave solder

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#44052

Spray fluxing VOC free, as operation HOURS before wave solder | 20 September, 2006

I am considering moving my spray fluxer into a completely separate operation. Has anybody any comments of sraying VOC free flux on boards, then putting them in a drier/holding rack for possibly say overnight, then running them through wave solder? We are a low volume high mix shop using wave solder pallets. My original plan is to move the spray fluxer ahead of but inline and continuous with the wave solder conveyor, but then wondered maybe we could flux in one operation, wait, and then wave solder later - this would allow infinite drying time, and reduce the complexities of basically gaining a longer conveyor length to my machine. Pete

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Rob

#44054

Spray fluxing VOC free, as operation HOURS before wave solder | 20 September, 2006

Good question - as it is a water based flux then you are going to get a very low level of solvent evaporation, and it's hardly going to be absorbing additional water whilst sitting around. (you actually want the water (carrier element) to evaporate).

I wouldn't personally be comfortable in moving the operation away from the wave for a number of reasons - including extra operations from spraying, storing, unloading & loading on the wave, and also moving chemicals around unneccesarily. I'd also be worried that the low levels of activators in my VOC flux could be compromised even by the very low evaporation rates.

Good luck,

Rob.

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#44065

Spray fluxing VOC free, as operation HOURS before wave solder | 20 September, 2006

As we are a low volume shop, the extra handling is not too much of a concern. My biggest concern is if the flux sitting on teh board for a long time (few hours) is going to cause any problems in solderability. My thought is that it should not as it really should not do much to the boards at room temperature. This is one way of working around the fact that I don't really have the evaporation length (capacity if you want to call it that) given my existing conveyor/preheater length. Pete

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RDR

#44076

Spray fluxing VOC free, as operation HOURS before wave solder | 21 September, 2006

Could you not just switch to alcohol based flux?

If your prob is getting the water off the board prior to hitting the wave, maybe you could install some type of convection to aid in this?

Russ

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greg york

#44093

Spray fluxing VOC free, as operation HOURS before wave solder | 22 September, 2006

Apply the bare minumum amount of VOC free typically 50% less than alcohol fluxes. By doing this you can keep the same top board temperature as alcohol, its only when people over flux do you need to boost up the preheater to volatise of the water. NEVER NEVER over flux only use as much as is required no more and yes I do sell fluxes Cheers Greg

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