25.10.2014
I’m really interested in upgrading my two sided exposure box to this kind of solution, but i have a doubt.
Has anyone figured out where the Electrolitic capacitor (2200uF and 30v recover) is fitted?
Looks like that is the working voltage of the capacitor, of course higher is fine (just not lower). When you are making DIY printed circuit boards, one of the popular methods requires UV exposure. This instructable outlines the construction of a double sided UV exposure box using the recent generation of high brightness UV LEDs. LEDs are far more energy efficient than either incandescent or fluorescent lamps offering between 5-10 times more efficiency making them cheaper to run and kinder to the environment. Whoops, did not immediately notice that the LED banks were set back enough to limit unevenness. Normal compact fluorescent tubes coupled with tracing paper do a very good job with exposing PCB traces. The resolution (reproduction from transparency to board) should actually be very good with UV LEDs since they generally have very narrow beam width.
Most visible LEDs are slightly less efficient than fluorescents and UV LEDs are much less efficient than fluorescent blacklights. Black light fluroscents also emit shorter wavelengths mainly 360nm to 380nm which is better for exposing PCBs than the near violet light emitted by most UV LEDs. LEDs do have the advantage of being more robust and if one of them breaks you can still use it. The fact that fluroscents contain mercury is a non issue because the amount found in a small tube is below the safe daily exposure limit. Also, adding the insult onto injury, Blacklight fluorescent would just conk out after 2,000 Hours and is easily breakable. The photo etching method needs 60 Watt radiated power at 10 cm target distance, also the wavelength must be 340nm (Near UV) with maximum wavelength 254nm, if you are going to use far UV light tube (190nm for example) the radiation will pass though the film (and though the plastic box) destroying all the photosensitive material, and causing cancer to you! A lot of you are just talking bollocks, I’ve made a UV exposure box using about 100 UV leds from ebay running off 12v, they are about 5 inches from my pcb. Simply print onto transparancy, flip the toner to the board and expose for 30 seconds – works like a charm.
And, another things to consider: Focal points, beam waist, divergence, and transparency of scanner glass (some of them use just plainly a fused Quartz glass for you to put paper on to be copied.


If vacuum UV was a problem then germicidal lamps would emit lots of ozone so will require lots of ventilation to prevent them being a health hazard but this isn’t the case. The worst blacklight tube will have an efficiency of about 15%, the best will be closer to 30% efficient. I’ve never needed to use a fan on a fluorescent enclosure but overheating can be caused by using cheap magnetic ballasts and inadequate ventilation. The same is true for some power LEDs, especially the cheap Chinese variety commonly bought off ebay. It is true LEDs though that last longer than fluorescent tubes but it’s important to note that both get dimmer over time.
If you buy cheap LEDs they’ll be very inefficient and much less efficient than a blacklight fluorescent.
You can buy a 2ft blacklight fluorescent tube for less than ?3 ($5 US) which will produce as much UV as many hundred UV LEDs. This may be an odd question but its 1AM in the morning and i’m too lazy to google it… what is that green glowing stuff that UV lights excite (in the pic, in the middle of the box)? PCB UV LED exposure, View PCB UV LED exposure, UVATA Product Details from Uvata (Shanghai) Precision Optoelectronics Co., Ltd. These LEDs have narrow ray (+-10 degrees), it helps to get sharp shadow on photoresist even if photomask is not cling to the PCB very tight.
That transparent box, although cool looking, makes me think you are asking for eye cataract. Normal glass usually absorbs too much of UV radiation, although I’m not sure if this is a problem around 400nm, or only for shorter wave lengths. Fluorescent blacklights are more efficient than visible fluorescent tubes and UV LEDs are much less efficient than visible LEDs. But if you’re going to use sterilization tube, you’re going to waste several watts here!
That’s just bad luck, a typical fluorescent with a properly rated ballast should last for 5000 hours, some last for over 10,000 hours. This UV LED Exposure Box was published in the magazine Emiter, and here’s what the author says on this project.
After some tests, it worked awsome with Positiv20 as with pre-sensitized PCB boards that i had at home. Because the current on which these leds( uv ultrbright 7000mcd – 400nm) operate is 20mA at 12V.


Djhamer has provided plans to make a UV LED system that is double sided so that you can expose double sided PDBs without having to flip and repeat half way through the process. It can also be used to make other things such as intricate photo etched parts (a subject for another instructable).
LEDs have a far greater life span than the other types of lamp measured in decades rather than months. While my technique is more or less stable, I sometimes have trouble with toner sticking to tracing paper: there are microscopic gaps, or even smearing.
Because, there are way too much free-path collision against lots of molecules in the air while trying to get Extreme UV onto your board, thus attenuate the useful flux of Uv emission.
There might be more efficient LED prototypes in the LAB but they’re certainty not ready for the mainstream. I have just bought an Ledengin LZ1-00UA00 Star LED from Farnell here in UK, about ?20, intending to build a light box.
LEDs mounted close to each other, so it provide well distributed light even with small deepness of box. The trouble is they can be a little pricey for the hobby enthusiast especially if you want the double side type. The frequencies being emitted are also in a tighter band making UV LEDs safer than the traditional UV tubes. Since the transparency is put back-to-back with the resist, lighting angle is not really an issue.
Also, it simply get so hot, to some point it would require fan cooling, if left on way too long. I suspect that I just have a crappy printer, but who knows, what if there’s some trick to better toner adhesion. If I try it out on the bench before making the box, is the reflected light dangerous, and will the goggles make it safe?
Will there be any problems doing this with UV, like the glass not being transparent, or the ink not opaque?



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Comments Uv led for pcb exposure youtube

  1. Devushka_Jagoza
    Can be inserted, but Hyperkin has gaps.
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    You could predict interest rates (which you can't.