Alberto,

I don't quite understand the brush step in the process either.  tough to
control... We had a coating issue long ago where the spray was failing to
cover those areas of the board that were shadowed by components, leads, etc.
When the assembly went through the dew point, condensation caused functional
problems.  We fixed it by applying an initial diluted spray to saturate the
assembly and all hidden surfaces -careful of bubbles-, and the second
(normal) coat got the coating to the proper thickness.

Ralph Vaughan

> ----------
> From:         Alberto Callo[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Alberto Callo
> Sent:         Wednesday, February 23, 2000 12:02 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] Conformal Coating Thickness Gau
>
> <<File: acallo.vcf>>
> Hello Tom and everyone,
>
> I am currently writing the procedures for conformal coating within my
> company.  We are experimenting all with two methods: brushing and
> spraying and the combination of both.  What is your exprience regarding
> conformal coating process? and how did you get best results?.  Our
> boards are hybrid, some are 90% through hole.
>
> So far we've found that spraying the board first with a thin coat and
> then brushing works the best.  Brushing itself causes lots of bubbles.
>
> Thanks
>
>
>
> Tom Burek wrote:
> >
> > The best way I know is when you conformal coat you include a glass
> coupon in the lot you are processing.  First you measure and record the
> thickness of the glass at least three areas on the glass.  You process the
> glass the same way and at the same time as your PCA's (spray, dip, etc.).
> When you are through processing and curing the conformal coat you measure
> the glass in the same three places.  The difference being the thickness.
> > Tom Burek
> >
> >  -----Original Message-----
> > From: [log in to unmask] [SMTP:MIME :[log in to unmask]]
> > Sent: Tuesday, February 22, 2000 6:10 PM
> > To: [log in to unmask]
> > Subject: [TN] Conformal Coating Thickness Gauge
> >
> >  << File: ENVELOPE.TXT >>
> >
> --------------------------------------------------------------------------
> --
> > Hello everyone,
> >
> > Can anyone direct me to the best way (or inspection equipment) to
> inspect
> >
> > the thickness on conformal coatings? TIA.
> >
> > Jason Gregory
> > Production Manager
> > Electrospec
> > (713)784-4900
> > (713)784-1194 fax
> >
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