I am in the stone age with a uv lamp.
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From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Sun Dec 07 14:20:41 2008
Subject: Re: [TN] Conformal Coat and Eddy Currents
Techies
Eddy-current testing uses electromagnetic induction to detect flaws in
conductive materials. There are several limitations, among them: only
conductive materials can be tested, the surface of the material must
be accessible, the finish of the material may cause bad readings, the
depth of penetration into the material is limited, and flaws that lie
parallel to the probe may be undetectable.
However, eddy-current testing can detect very small cracks in or near
the surface of the material, the surfaces need minimal preparation,
and physically complex geometries can be investigated. It is also
useful for making electrical conductivity and coating thickness
measurements.
Useable for conformal coatings? It doesn't seem suitable. I have been
experimenting with lasers, but frankly this seems an overkill and
reminds me of the Pen v Pencil argument. Russia figured the simplest
way to write in space was to use a pencil... Measuring thickness using
a readily available micrometer. Granted, measuring thickness on sharp
lead ends and component legs os real tough - but coatings have been
used to protect electronics since 1940 and they have done a good job.
Hope this helps
Graham Naisbitt
On 4 Dec 2008, at 19:18, Douglas O. Pauls wrote:
> Good afternoon all,
>
> A question for this most excellent forum. Does anyone here use eddy
> current methods to measure applied coating thickness on printed
> circuit
> assemblies? If so, can you share your opinions on the methods and the
> equipment?
>
> There are testers on the market that do this and one of our design
> engineers is currently suprised at how we are using "stone age"
> technologies (micrometer) to measure coating thickness.
>
> Doug Pauls
> Rockwell Collins
>
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