Ioan,

You should be able to fit a dispensing nozzle to your selective coating machine, it should be able to cope with at least 2 dispensing valves. 

I'd suggest you could look at a UV curable masking material, and use a needle valve to dispense and a UV light wand to spot cure after dispense.

There are some second generation acrylic gel materials on the market that don't crack in the same way as you have seen. They can be needle dispensed immediately prior to coating.

If you still have issues with uncontrollable splashing from your film coat valve then maybe you would be better served fitting a 3rd valve to your platform and using a low volume low pressure spray application.

Please don't hesitate to contact me offline if you'd like to discuss further.

Best Regards,

Phil

European Sales Manager
PVA

+44 7703 795422

Sent from my iPhone

On 21 Jan 2013, at 13:05, Ioan Tempea <[log in to unmask]> wrote:

> Dear Technos,
> 
> Got a tough one now!
> 
> We apply 1B31S with our Asymtek selective coating machine and there are 8 difficult connectors, where coating infiltrates inside and on the pins. What can I do to prevent this from happening?
> 
> We've tried to manually lay down some non-diluted coating around the parts. Kinda stops infiltration, but it's long and manual, many bubbles in the coating layer. We've tried gel coating around the connectors, but it cracks, leaving a lot of room for infiltration. Not to mention that the closer the selective nozzle gets to connectors, the more prone we are to finding spots on the pins (it seems impossible to completely eliminate satellites when the nozzle head changes direction or at start-stop).
> 
> Ideally we would find something that can be dispensed around those connectors in a controlled manner (even if we need to buy some sort of table top dispensing machine) so that we seal them, followed by selective dispensing on the rest of the board. We really want zero or minimal manual work, as it's not repeatable.
> 
> Any suggestions?
> 
> Thanks,
> 
> Ioan Tempea, ing.
> Ingénieur principal de fabrication / Senior Manufacturing Engineer
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