blacklight, UV light?

[zachtheterrible]

Im just curious if I have to use a UV light made for the purpose of developing boards, or if I can use a regular blacklight that I can buy cheaper than a UV light

 

[evandude]

if you've been reading the threads on here lately, you'd see that many people use normal flourescent lights.

 

[jbeng]

Here's a link to a thread where we discussed the fluorescent UV lamps you're talking about. In that thread there's also a link to a source of the lamps for only like $5 US each. As I seem to recall when I bought mine several years ago, they were over $20 US each. I've always had real good results with them.
https://www.electro-tech-online.com/threads/pci-card-blank.9965/
JB

 

[pike]

I read somewhere that Flourescent lights are basically UV tubes with a white phosphor coating. When the UV lights hits the phosfur it changes the wavelength of the UV into visible light. but some of the UV light remains unchanged and becomes waste energy (as it doesn't provide lighting)

It should work fine.

 

[Screech]

blacklight is uv light.
Get it from Flourescent tubes that have BL written on them,
from electrical suppliers.
Standard Flourescent tubes have a coating on them that filter out the harmful uv rays.
Don't use Black Light, light bulbs. I read that they are useless.

 

[audioguru]

Blacklight tubes have a coating to absorb harmful high frequency UV rays that are needed to develop boards quickly. Medical UV tubes have the high frequency rays and are used to kill bacteria and stuff.
Now that the earth's ozone layer is depleted, sunlight is much improved to develop boards quickly. Pick a sunny day when the weather forcasts a hole in the ozone layer above you. :lol:

 

[Random]

Kinda specific - I'm looking for a UV fluorescent tube about 10" long and about 3/8" in diameter. (Who was it that had the fantastic idea to turn a broken scanner into a developing box? :O) And audioguru - if standard blacklights don't transmit the rays I want, which kind of bulb should I get?

Also - how sensitive are these boards to regular household light, when the backing's removed? Do I have to set up a darkroom-type environment to expose and develop my boards cleanly?

 

[audioguru]

audioguru - if standard blacklights don't transmit the rays I want, which kind of bulb should I get?

Someone on another forum said to use medical bulbs. Someone else said today to use blacklights. I have never used a photosensitive pcb, so I dunno.

Also - how sensitive are these boards to regular household light, when the backing's removed? Do I have to set up a darkroom-type environment to expose and develop my boards cleanly?

I dunno that one either, but think that florescent bulbs and sunlight would cause trouble.

 

[zevon8]

It really depends on the material used. Some photochemical resists are more sensitive than others. We do silk screens at work using the same process. It is a messy job so we often coat several screens at one go, saving them for later use. They last for about 2 weeks in a reasonably dark enclosure ( 3 layers of black garbage bag ) For exposure we just use a 500 Watt halogen work light, about 2 feet away, it takes about 15 minutes to expose. The screens range from 12" square to over 3 feet square. Worst case, the exposed resist is harder to rinse away after if they were partially exposed under the patern, so we always tend to put a heavy layer on.

We have tried other resists, and some were very sensitive, you almost needed a proper darkroom to avoid "shadowing" and half-exposed screens.

I say just experiment on some board, empirical proof is always the best.

 

[zachtheterrible]

Thanks for the help everyone.

I guess Ill just have to experiment. Im going to try flourescent first because i can get them from home depot instead of ordering them.