Thanks, Jim and Doug

This assembler is asking for 150mils. 
One reference I found suggested creating an area defined as a NO COAT zone, 
and defining the area to be COATED, separated by a neutral zone that wouldn't 
be inspected either way.

This could easily be done in the design by just "drawing" the neutral area 
between zones with a 60 mil width (90mils away from the connector example 
used below). Does that sound reasonable? or am I thinking wrongly? (or am I 
over-thinking this whole scenario?) 

The DFM mantra inspires me to keep these downstream processes in mind, and 
maybe the 150 mils is a combination of coated, notinspected, notcoated 
clearances, but it sure ties my hands during component placement around 
these areas.

Jack     


.
On Wed, 19 Jan 2011 15:58:41 -0600, Douglas Pauls 
<[log in to unmask]> wrote:

>Stop that Jim.  I have Hillman signing me up for all kinds of things, he
>does not need assistance.
>
>Like Jim, for much of our coating, we use a 60 mil clearance around
>connectors, precisely due to the wicking that Jim describes.  Way too easy
>to flood the connector.  Machine application is not that much difference
>beween you get much more wicking that way, especially if you spray
>(thinned material wicks more).
>
>Now, this clearance also creates potential failure sites in humidity. What
>I would recommend around connectors is to find a no-flow sealant to
>permanently seal the base of the connectors, then coat up to that sealant.
> That way you get a continous protective film.  Same consideration if you
>have components you need to seal off.
>
>Doug Pauls
>
>
>
>Jim Carlson <[log in to unmask]>
>Sent by: TechNet <[log in to unmask]>
>01/19/2011 03:24 PM
>Please respond to
>TechNet E-Mail Forum <[log in to unmask]>; Please respond to
>[log in to unmask]
>
>
>To
>[log in to unmask]
>cc
>
>Subject
>Re: [TN] Conformal Coat vs. Masking
>
>
>
>
>
>
>Jack,
>
>Our normal manual clearance is .06", to prevent wicking on any leaded
>type of component.  If you have small isolated areas to mask, this will
>work.  But if it requires a lot of different components/areas, you will
>be driving touch time and intricate masking.  Perhaps Doug Pauls can
>provide adequate clearance for automated methods.
>
>Jim Carlson
>Quality/Configuration Manager
>L-3 Communications
>Applied Signal & Image Technology
>443-457-1111 Ext. 238
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
>Sent: Wednesday, January 19, 2011 4:10 PM
>To: [log in to unmask]
>Subject: [TN] Conformal Coat vs. Masking
>
>Does anyone know a sensible guideline for how much space to leave
>between
>conformal coated areas and other areas that should NOT be coated?
>
>We have some high voltage areas of circuitry that need to be coated,
>near other
>connectors and mounting holes that will not be coated. The problem is,
>the
>assembler is asking for far more "isolation" than the engineers!
>(might it be a different clearance for manual vs. in-line?)
>
>Seems like this would be common knowledge, but I just can't find it
>anywhere...
>
>thanks,
>Jack
>

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