Hi, Paul,

Can you apply a dam of UV-cureable mask along the connector prior to
coating, or even seal the offending area with something like Kapton tape?
These automatic coating machines are pretty accurate, and people seem to
have gotten out of the way of doing conformal coat masking, as it's a
costly extra process, but sometimes it's necessary, as capillary action is
a powerful force, much relied upon for underfilling.

Have you tried reducing the coating thickness a little on the last passes
near the connector?

Pete Duncan





                    Paul
                    Bannister            To:     [log in to unmask]
                    <PBannist@MTL        cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST
                    NH.COM>              Group)
                    Sent by:             Subject:     [TN] Conformal Coating Wicking
                    TechNet
                    <[log in to unmask]
                    ORG>


                    05/11/01
                    12:00 AM
                    Please
                    respond to
                    "TechNet
                    E-Mail
                    Forum.";
                    Please
                    respond to
                    Paul
                    Bannister






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.

###########################################

This message has been scanned by F-Secure Anti-Virus for Microsoft
Exchange.
For more information, connect to http://www.F-Secure.com/

---------------------------------------------------------------------------------

Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET
Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
---------------------------------------------------------------------------------

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------