hi,

can't you use a temporary latex maskant to prevent this wicking?

phil

-----Original Message-----
From: Paul Bannister [mailto:[log in to unmask]]
Sent: Thursday, May 10, 2001 9:00 AM
To: [log in to unmask]
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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