I assume you are using UV tracer conformal coat.  one easy way:
cover part of the substrate using Kapton tape (prefer dark
substrate)-->spray or dip coat and cure the material (make sure you record
number of pass of the spray or withdraw speed of the dip)--->use a knife to
cut the conformal coat along the tape line and remove the tape---> go to UV
microscope and visually measure the conformal coating thickness (make sure
you calculation is include tilting angles if the sample is tilt) (normally,
you can take a photo and measure the thickness from the hard copy... make
sure the UV light is low power, otherwise, your coating would appear to be
thicker due to light scattering)...
Never use the method for process control(only for process development), but
it works wonder when you try to select conformal coat, uniformity, coverage,
pin holes, bubbles...all visible..
                                 jk
At 04:33 PM 9/30/99 -0500, you wrote:
>Good day. How do you measure conformal coating thickness, without sectioning
>a board or a coupon? Which method (brush, dip, spray) has the best
>repeatability for thickness?
>We build board assemblies to IPC Class 2 and 3 and have no idea if we meet
>the requirements of paragraph 10.1.2.1.
>
>Regards,
>Dave Hipp
>Woodward Aircraft Engine Systems
>Electrical Production Engineering
>(815) 639-6732
>FAX (815) 636-6040
>
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