We had the same problems. It's amazing how much humiseal will wick
vertically in a connector! Our cure was to use washable masking around
the bottom edges of the connector to prevent the humiseal from entering
the bottom. It seemed to work pretty good for us.


Paul Bannister wrote:
>
> I am having a problem with conformal coating wicking into connectors on a
> PCB and would like TechNet's advice.
>
> We spray a mixture of 1 part IB31-EPA Humiseal with 1.6 parts Humiseal
> thinner 600 from a Nordson automated coater and than cure the boards in a
> NC-100 Select Cure oven.  The connector with the problem is a Samtec BCS
> series pass through connector.  If any amount of the conformal coat mix
> comes into contact with the pins of the connector on the topside of the PCB
> the material is wicked up inside the connector.  The outside of the
> connector pin is than "glued" to the inside of the connector housing causing
> contact problems at low temperature (-40C).
>
> Does anyone have suggestions on how to prevent the wicking while still
> covering the solder joint on the connector.  Samtec does not offer a sealed
> connector in this series because of the pass through feature.
>
> Thank you.
>
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