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May 2010

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Subject:
Re: Wrinkling of conformal coating
From:
Inge <[log in to unmask]>
Reply To:
Inge <[log in to unmask]>
Date:
Fri, 7 May 2010 19:01:08 +0200
Content-Type:
text/plain
Parts/Attachments:
text/plain (125 lines) 
Ioan,
I think I know what's smoking...it's the CAFfein.
Inge
--------------------------------------------------
From: "Ioan Tempea" <[log in to unmask]>
Sent: den 7 May 2010 18:07
To: <[log in to unmask]>
Subject: Re: [TN] Wrinkling of conformal coating

> In case you guys thought you got away by talking about alien espresso 
> machines, I have one more question.
>
> Took a bare board from stores and stuck it into the reflow oven. I have 
> noticed smoke coming out from the tunnel while the PCB was in. Not huge or 
> thick, but just enough smoke to notice it. Could this mean anything 
> regarding the board, like not cured something, poor FR-4 or else?
>
> Thanks,
>
> Ioan Tempea, ing.
> Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
> T | 450.967.7100 ext.244
> E | [log in to unmask]
> W | www.digico.cc
>
> N'imprimer que si nécessaire - Print only if you must
>
>
>
> Dear Technos,
>
>
>
> Back to orange peeling, this time concerning conformal coating, please see
> http://ipc-technet.groupsite.com/galleries/photo/124230
>
>
>
> The coating is applied with an Asymtek Century machine and is a Conap 1170
> acrylic.
>
>
>
> ˇ         The board is left curing in ambient temperature, no
> acceleration. Starting with an even coating, in about 20-30 minutes the
> liquid seems to move towards a certain area (no rippling at this moment).
> After another 10-15 minutes the rippling effect sets in.
>
> ˇ         We thought that due to the almost 2 minutes lag between the
> coating of the first and last image, the drying of the coating layer is
> not even and the one side curing first pulls on the liquid at the other
> end. So we've cut the panel in 2, accelerated the machine, the problem is
> still there.
>
> ˇ         The boards are laid as flat as possible, maybe not perfectly
> horizontal, but not worse than others with the same coating, that do not
> show any issue
>
> ˇ         Just to make it more difficult: grabbed a non-populated panel
> from the stores, coated it, placed on the same flat surface, and guess
> what: no issues.
>
>
>
> The PCB has Taiyo PSR 4000 MP soldermask.
>
>
>
> So I would need your guidance in clarifying where is this coming from and
> how to fix it.
>
>
>
> Thank you,
>
>
>
> Ioan Tempea, ing.
> Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
> T | 450.967.7100 ext.244
> E | [log in to unmask] <mailto:[log in to unmask]>
> W | www.digico.cc <http://www.digico.cc/>
>
>
> N'imprimer que si nécessaire - Print only if you must
>
>
>
>
>
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