Ed

Apologies that you have not had a reply, personally I have been kinda
preoccupied with covering the holiday period - you know, doing 3 jobs
instead of 1!

Anyhow, you should certainly be cautious in your choice of oven. The coating
will almost certainly contain flammable solvent. As a result you would be
well advised to use intrinsically safe ovens. By that I would use ex'd'
rated construction. This would generally involve cast alloy heater panels
and adequate fume extraction.

Check with the oven supplier that they can give low temp profiles. If you
heat the coating too fast, you will cause coating defects such as solvent
bubbles etc.. The probable peak temp would be around 80 deg C or 175 deg F.

Hope this helps but call me if you need more.

Regards

Graham Naisbitt
[log in to unmask]
www.concoat.co.uk
Concoat Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK
Tel: +44(0)1276691100
Fax: +44(0)1276691227
----- Original Message -----
From: Ed Holton <[log in to unmask]>
To: <[log in to unmask]>
Sent: 11 August 2000 14:41
Subject: [TN] conformal coat curing ovens


> Need some help here everyone:
>
> We need to implement a spray conformal coat system.  We are well on our
way
> to selecting the machine, but I have some questions about curing.  We are
> using an acrylic, one part conformal coat.  It cures at 90-100C for about
> 20 minutes.  We will be spray conformal coating both sides of the PCB.
> This will be an in-line process.
>
> For those of you in the field already doing this, please give me some
> general information about the curing process.  We had planned on using a
> convention oven (just like for SMT) , but what about the safety of the
> ovens.  Do I need a special explosion proof oven, or can I do it by using
> an standard reflow oven and venting outside or through fume extractors.
Is
> there much smell associated with doing this.
>
> I presently have the process going in a Dip conformal coat machine.  Here
> we have air motors, but we vent outdoors.  It is not considered "explosion
> proof" if you classify explosion proof as the thickness of the metal used
> for construction.
>
> Thanks
>
> Ed Holton
> Manufacturing Engineer and Group Leader
> Hella Electronics
> Telephone (734) 414-0944
> Fax (734) 414-0941
>
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