Kain Posted January 7, 2005 Report Share Posted January 7, 2005 When using the photo-exposure method to transfer the artwork, we all know that it has to be perfectly alligned especially if we are making double layer boards. Since this cannot be done under regular light as we all know, I wonder if it can be done under light emmited from white LEDs? The reason why I am guessing it might work is because they are basically RBG LEDs all in one, but they do not emmit UV which is needed for the board to be exposed. Any suggestions? Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 8, 2005 Report Share Posted January 8, 2005 Hi Kain,A white LED isn't the same as an RGB LED. Just read a datasheet.A white LED is really a blue one with a yellowish phosphor added. That is why they aren't very white. The light comes from a single location on the chip so it can be easily focussed.An RGB LED has 3 separate LED chips inside. You need to separately power those LEDs and adjust the ratio of their currents in order to get white. Since the colours are produced at different locations, they are difficult to focus. Quote Link to comment Share on other sites More sharing options...
Kain Posted January 8, 2005 Author Report Share Posted January 8, 2005 Good to know. I think I read few days ago about different processes of making white LEDs and one was actually by combining RGB by adding dots of different compounds on phosphorus to make all 3 colors, thus white, but anyways. The main question is still would it be possible to work under this light without trashing the board? I would check on the datasheet though. Thank you anyways audioguru 8) Quote Link to comment Share on other sites More sharing options...
EnigmaOne Posted January 8, 2005 Report Share Posted January 8, 2005 Just an FYI:Some of the white LEDs do have a certain amount of UV emission (obviously, not the RGB units). You can, in fact, buy UV LEDs, though they aren't what I'd call inexpensive at this time. Quote Link to comment Share on other sites More sharing options...
Kain Posted January 8, 2005 Author Report Share Posted January 8, 2005 Well, if you check on ebay you can find pretty good deal - 100 UV LEDs for less than 10$ in total. I think this is more than cheap ;D. By the way, please if you know something about using UV LEDs for photo-exposure please post on:http://www.electronics-lab.com/forum/index.php?board=13;action=display;threadid=2406 :) Quote Link to comment Share on other sites More sharing options...
EnigmaOne Posted January 8, 2005 Report Share Posted January 8, 2005 I wish I could claim specific knowledge but, for some reason, I have a growing interest in making some sort of space-efficient exposure drawer for things like litho film and pc boards.If I come up with something interesting, I'll certainly share my findings. Quote Link to comment Share on other sites More sharing options...
Kain Posted January 9, 2005 Author Report Share Posted January 9, 2005 Oh well, it seems I will need to do trial and error - I have few high intensity white LEDs so I'll expose little piece to see how it goes 8) Quote Link to comment Share on other sites More sharing options...
Kain Posted January 10, 2005 Author Report Share Posted January 10, 2005 Alrighty. In case somebody is interested in the results, besides me of course ;D, here you go. I exposed precoated board under white LED's light for 10 min. The LEDs are rated 10000mCD so they are not exactly weak. I placed the board right infront of the lenses for maximum illumination and still it did not get exposed - it did't develope even slightly. Then I exposed half of this same board to regular luminiscent lamp and this half developed right away. In conclusion, if you guys want to work under light - to cut precoated boards, to make the coating and so on I believe high intensity white LEDs are the right solution before lamps. First, it's white light meaning you would be able to see bettter under white light than monochromic red for example; LEDs are way more energy efficient, and LEDs have way longer life on average. The only disadvantage is the required low V. Time to build myself a lamp now ;D Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 11, 2005 Report Share Posted January 11, 2005 Hi Kain,That's great! Red work-lights aren't needed anymore.Are you going to make a white LED desk-lamp?When you turn-off the desk-lamp, are you also going to have a white LED spotlight to light your path to the door? ;D Quote Link to comment Share on other sites More sharing options...
Kain Posted January 11, 2005 Author Report Share Posted January 11, 2005 I might ;D Quote Link to comment Share on other sites More sharing options...
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