Graham,
Thanks for the reply but.......
We've qualified and re-qualified our conformal coating processes over the
years and have always passed (UR, AR and XY). My question is, is there an
in-process test for conformal coating adhesion that is generally accepted
by the industry AND is anyone doing it? Sort of like keeping an eye on the
cleaning process by doing a ROSE test. Not a good qualification tool but no
too bad for in-process.
Thanks,
KennyB
At 12:58 PM 11/22/99 -0000, Graham Naisbitt wrote:
>Kenny and other Techies,
>
>I understand that Paralene type coatings are particularly sensitive to
>"No-clean" residues - they do not adhere.
>
>You will also find that certain coating formulations and polymers will
>behave in different ways to different surface conditions. For example,
>certain acrylics do not stick well, but other acrylic resins work fine
>example: 1B31 and 1B73 from HumiSeal. Urethanes generally stick like you
>know what to a blanket, yet we have had instances where the acrylics have
>worked better. As regards silicones, how the hell do you run an adhesion
>test for these given that no tape will stick to the silicone? Yet silicones
>do represent a significant part of the coating business.
>
>As I said in an earlier posting, only if you fail environmentals would poor
>adhesion become important. A friend of mine (yeah I do have some :-) )
>pointed out rather well - As far as we can tell, coatings are not
>intelligent, so if they stick well to metals laminates and plastics, but
>don't stick to certain "treated surfaces", how do they know the difference??
>I always wonder about thermos flasks for similar reasons - they keep hot
>things hot and cold things cold - but how do they know? SPOOKY! :-)
>
>However, the real issue as Bernhard indicated, is to evaluate SIR or IC
>measurements. This way you would be able to establish whether there will be
>any reliability issues for the end product. Understanding electro-chemical
>reactions and maintaining the desired quality or reliability is the subject
>of major new developments in SIR testing standards - watch this space....
>
>Regards,
>Graham Naisbitt
>
>[log in to unmask]
>
>WEB: http://www.concoat.co.uk
>
>CONCOAT Ltd
>Alasan House, Albany Park
>CAMBERLEY GU15 2PL UK
>
>Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>----- Original Message -----
>From: Kenny Bloomquist <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: 19 November 1999 14:54
>Subject: [TN] Speaking of Adhesion of Conformal Coating
>
>
>> I'm curious what other companies do as an in process test for conformal
>> coat adhesion, if anything.
>>
>> I'm particularly interested in Parylene but also curious about UR and AR.
>>
>> If you do in process testing what spec do you follow, if any, and what
>> materials do you use, i.e. tape type, Exacto, etc.
>>
>>
>> Thanks to all responders,
>>
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