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Subject:
From:
Graham Naisbitt <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 20 Mar 2000 11:55:22 -0000
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Grant

To quote the great Sir Winston Churchill, "Round Objects!" to the rep in
question.

As a manufacturer of conformal coatings I am more than just dismayed at
these sorts of comments. Too frequently, customers are using conformal
coatings to hide reliability problems faced with no-clean regimes. This only
serves to give us a bad name because you may be making the problem bigger
than it would be without the coating - they seal IN as well as out!

Can you coat over no-clean? Yes. How do you achieve this? By using latest
SIR test methods and modelling your full production process on SIR coupons.
The you may find out if it will work.

As some of you may know, Dr Chris Hunt from the British National Physical
Laboratory presented initial results of a major new research study in this
area which caused more than a little disquiet from the recipients.

Contrary to the recent postings on a similar thread from both Brian Ellis
and Per Erik Tegehall, we now have the scientific evidence to prove the
benefit of SIR testing as a reliability predictor.

Now Grant, what is your consequential liability risk if the rep is wrong? Is
your product safety critical? Are you really willing to take this risk on
the say-so of a rep?

Ask him to do the testing for you and prove it!

Hope this helps you.

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: Grant Emandien <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, March 20, 2000 9:24 AM
Subject: [TN] Coating of assemblies with no clean fluxes


> Hi all,
>
> The debate on cleaning of fluxes as well as the use no-clean fluxes seems
to
> hang around forever. We have been informed by our solder an flux supplier
> that assemblies with no clean fluxes can be conformally coated without the
> need to clean the boards.
>
> The argument is that the high temperatures of the reflow oven 'burns off'
> the active ingredients, leaving only inactive residues. These flux
residues
> do not have to be cleaned and can supposedly be coated. The rep. believes
we
> are taking a backward step by possibly opting to use water-based flux. Is
> this pure sales talk?
>
> Is anyone able to offer any advice or insight, or been able to assess the
> environmental and electrical performance of such assemblies.
>
> Regards
> Grant
>
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