Hi, i am on the lookout for UV tubes at the moment for a UV exposure box, I am getting somewhere, but am wondering how effective 100 UV leds would be, so like a 10x10 matrix of LED's all lit up behind some frosted glass. would that be effective. heres the spec: Emitted Colour : ULTRA VIOLET Size (mm) : 5mm T1 3/4 Lens Colour : Water Clear Peak Wave Length (nm) : 385 - 395 Forward Voltage (V) : 3.2 ~ 3.8 Reverse Current (uA) : <=30 Luminous Intensity Typ Iv (mcd) : Average in 2000 Life Rating : 100,000 Hours Viewing Angle : 20 ~ 25 Degree i suspect they are the wrong wavelength, but thought it was worth the questions.
You can use UVA tubes for exposure units no problem. Blacklight tubes (345 to 400nm) are in the UVA spectrum and people use those with no problems. The problem with using UV led's is that the beam pattern is so narrow, and they aren't anywhere near bright enough.
Thats for clearing that up! I hear you can use UVA, UVB and UVC (shortwave) for exposure, one of my dads friends is sopposed to be dropping off some UVC tubes for me, but i doubt anything will come of it. In the mean time i am scavaging for some more UV facial saunas!
Be careful with the UVC ones - they are very hazardous. Make sure they are fully enclosed when you turn them on as they will destroy living tissue.
UVA ones are bad enough, quoting from my GCSE RESMAT coursework (mostly bull if you know what i mean " When I first started etching, I was using the same briefcase and tubes, but instead of a Frosted piece of glass, I was using a “Lampshade” type dog collar as a diffusing lens. This promptly melted, UVA light gives off a lot of heat (or seems to even if it is not meant to as this is PURE UVA (not backlight) it is EXTREMELY dangerous to your eyes) It is the “White tube type” (if you look at it (even for 1 second), you have a purple blob in your vision for about 2 minutes). It is extremely important to use UVA as UVB is not so effective and UVC is artificial used to kill germs and is Very dangerous to all things living. I then used the Frosted glass I use now as a different diffusing lens, I still have a fainter are of the surface (a dark spot), which I try to avoid when exposing. The other major issue I had that cost me about £20 in chemicals and board is that normal transparencies (like OHP stuff) is NOT DENSE enough. If you print onto them with a laser printer and hold them up to the light, you still see light through the dark bits. The solution I find is to print two sheets off and use them together, which increases their density by about 300%. I use one sheet of really expensive (50p a sheet) transparency and one sheet or ordinary transparency and have had perfect results since! The expensive stuff is diffused though (not completely transparent) which helps a bit. I have also found that the Ferric Chloride works vigorously at over 50 degrees C, at the moment I am using a plastic tray inside another bigger one. The bigger one is filled with boiling water and the inner one filled with the Ferric Chloride. This proves to be effective as it reduces etch times from 45 minutes down to 8 minutes. I have also reduced costs by storing the ferric chloride after use in a plastic bottle (it eats all metals, even jam jar lids) since it lasts for about 5 etches and by using new Photo board which requires half strength developer. " but my briefcase is bad, so i am going to try and make a double sided system.
