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Date: | Tue, 4 Feb 2014 06:25:44 +0000 |
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Hi Arnaud
I agree with Doug on this on using Dyne Pens although with no clean
processing generally you are lucky if you can get close to the range of
35-40! We tend to be working in the lower range of this.
It's also solder resist / coating dependent. Don't dismiss the energy value
out of hand immediately. There is no logic sometimes to selection. We found
one case where we tried absolutely any coating we could find to stick to a
solder resist and only one did. No idea why and none of the chemists could
explain.
Best Regards
Lee Hitchens
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: 03 February 2014 17:01
To: [log in to unmask]
Subject: Re: [TN] [COM] Solder Mask Surface Tension for Conformal Coating
Adhesion
Arnaud,
I think you are asking about surface energy rather than surface tension.
We use the readily available Dyne Pens which have solutions calibrated
back to an ASTM standard.
I generally use this rule of thumb regardless of the coating used.
Under 30 dynes/cm: Coating adhesion will be poor
30-35 dynes/cm: Coating adhesion will be slightly better, but you can
expect more frequent cases of delamination.
35-40 dynes/cm: Coating adhesion generally good, but can have some
periodic delamination or adhesion issues.
40-45 dynes/cm: Coating adhesion is good and only rarely will you see
delamination problems
45+ dynes.cm: Good adhesion.
Of course, there will always be special cases but this is a good starting
point.
Doug Pauls
From: GRIVON Arnaud <[log in to unmask]>
To: <[log in to unmask]>
Date: 02/03/2014 10:48 AM
Subject: [TN] [COM] Solder Mask Surface Tension for Conformal
Coating Adhesion
Sent by: TechNet <[log in to unmask]>
Hello TechNet,
I would like to sense the best practices in terms of solder mask surface
tension with respect to conformal coating adhesion :
- Which standard/test method are you using?
- Which requirement (e.g. minimum value in dyn/cm²) would you
accept for the various CC types (acrylics, urethanes, silicone, parylene)?
Thanks in advance for the insights.
Best regards,
Arnaud Grivon
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