1B31 is available in a gel form, which can be dispensed around the base of
the connectors and then cured.  Once cured, the coating can be applied as
usual and capillary wicking is eliminated.  It adds a separate stage and
takes a little time, but it is based on the same resin so no compatibility
issues.  Some volume customers use this method very successfully here in the
UK.

Best Regards,

Phil Kinner (Masquerading as Alan Brewin on the TechNet!)
Concoat Ltd

----- Original Message -----
From: "Paul Bannister" <[log in to unmask]>
To: <[log in to unmask]>
Sent: 10 May 2001 17:00
Subject: [TN] Conformal Coating Wicking


> 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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