Doug,
The "black light" is long wave UV-A, around the 365nm mark, typically at
low to moderate intensity - a few mW/cm2. "Black light" because the
visible light is filtered out.
Most UV radiometers designed to measure adhesive curing lamps will be in
the right wavelength area and should be able to measure down to 1 mW/cm2
accurately. 1-2 mW/cm2 of long wave UV is what you get on a sunny day.
Your blacklights might be about 10 mW/cm2 maximum. Avoid radiometers
which measure short wave, which you do not need, and which add to the
expense.
Distance is a big factor, because in general terms, the intensity of
this light will fall off with the *square* of the distance. Try and lock
down the distance as a variable if you can. Also, the indicated wattage
of the bulb is not necessarily a direct indicator of the output
intensity in the wavelengths you are interested in - best to measure.
See companies like DYMAX or UV Process Supply. I think the latter do
something for a few hundred dollars which might do the trick.
Regards,
Peter
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Peter Swanson [log in to unmask]
INTERTRONICS http://www.intertronics.co.uk
Tel: +44 1865 842842 Oxfordshire, England
INTERTRONICS is dedicated to providing quality material, consumable
and equipment solutions to the high technology, high performance
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas O. Pauls
Sent: 13 June 2007 16:15
To: [log in to unmask]
Subject: [TN] Black light intensity meters
Good morning all,
I have two questions that relates to conformal coating practices. We
have a situation internal where we conformal coat assemblies in booths
outfitted with black lights and the coating has a fluorescent dye marker
(Humiseal 1B31). Most booths have four 22W black light bulbs. Our
inspectors use a circular magnifier outfitted with a circular black
light bulb. The latter has a stronger output, possibly because the
black light bulb is much closer to the surface being inspected. This is
leading to inspectors finding coating "defects" which cannot be seen
with the black light illumination in the coating booths. So we have a
running dispute between inspectors and operators.
1. Is there a meter that any of you would recommend by which we can
measure black light intensity at various distances? I know there are a
number of them out on the market, but many are also of the variety that
check the UV output of high intensity devices such as UV imaging of
solder masks.
2. What do your workmanship standards say regarding inspection under
black light? Distance, magnification, intensity?
Thanks.
Doug Pauls
Rockwell Collins
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