Hi, Ioan
Are the connectors straight (vertical) connectors, or are they right angle connectors?
I once had an issue with coating seeping up inside vertical connectors and going down into the mating contacts. It happened because the keypins were not sealed. Coating from the surface of the PWB could seep up between the barrel nuts of the keypins and the connector wall around the keypins, then out across the mating surface and then down into the female receptacles. We were masking the top surface very thoroughly by wrapping tape around the perimeter of the connector and pinching it shut, but we did not realize the coating was not entering from the top down, but from the bottom of the connector up through the keypin holes on each end of the connector. Right angle connectors did not display this issue because the coating was not sprayed on the back of the connector.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Monday, January 21, 2013 7:05 AM
To: [log in to unmask]
Subject: [TN] Coating around connectors
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 [signature002]<http://www.digico.cc/>
950 RUE BERGAR, LAVAL, QC, H7L 5A1<http://g.co/maps/2gh3f>
T+ 1 (450) 967-7100, EXT244
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