Help needed in making UV PCB Developing Box

[MrsR]

Hi! Guys,
I am making a new UV Box and need help.
Where do you get low priced UV Lights?

I saw a UV set up using the insides of Bayonet Light Bulbs Are they available in Australia.

CHEERS
Rachael

[zenith1111]

Hello,

I've built a UV box out of an old scanner. I took the "guts" of the scanner and replaced it with 4 9W UV fluorescent lights bought on eBay.

You don't need "true" UVC lamps, like the germicidal ones, I use these:
http://www.ebay.com/itm/1-X-9W-Nail-Art-UV-Machine-Tube-Dryer-Lamp-Light-Bulb-/250842013997?pt=LH_DefaultDomain_0&hash=item3a6759612d
I believe they are used to cure nail varnish, I don't have the instruments to properly measure but they appear to emit mostly visible light, I do believe they are a lot safer for the eyes and skin than the germicidal ones.

These two pin ones generally have a built in starter, you only need to connect them to a 7 or 10W ballast (if you have 240v AC mains you probably can get away with wiring them in series with a 18 or 20W ballast).

With 4 of these fluorescents I only need around 50 seconds on positive pre-sensitised Kingsten PCBs.

[Kremmen]

Do avoid the lamps producing "germicidal" UV-C radiation. That is borderline ionizing already, i.e. the UV-C quanta have enough energy to act like soft x-rays. Enough exposure to that kind is a recipe for premature health issues. Also, that kind of UV source is not at all necessary for PCB exposure. I have made an ad hoc exposure box from a couple of "black light" fluorescent bulbs that look like ordinary energy saving lamps of the "pear shaped" kind. Works like a charm with some 10 min exposure time.

[notsob]

Here's one using UV LEDs

http://en.elektronicastynus.be/projects/81/

[hlavac]

Here is mine with UV LEDs. 40 seconds exposition.

[Paul Moir]

Timely; I'm currently in the middle of a project involving those germicidal bulbs.

Aliexpress has tonnes of them.  Just google aliexpress germicidal.  There are a bunch of US resellers of those bulbs, but why not go to the source?  You want the ones with transparent bulbs, not the ones that look white.  There is a price floor on them due to the somewhat expensive fused quartz glass tubes.

(the 4 pin base ones have "Circline" G10q bulb bases.  The 2 pin on each side bulb are far more normal.)

There are some that let out the 184nm line which generates ozone, but those are usually special order. 

If you want to go local, check out local lighting suppliers; the ones that sell light bulbs commercially.  GE and Phillips both make them.  Or anyone into water treatment (including shops that are into well water stuff.) 

[poorchava]

I bought a 36W "hybrid nail poilsh  " curing machine. Used for $5.5 or so. I have yet to put it to test.

[BravoV]

Bought at local Ace Hardware store, 10 watts insect FL lamp as Mikeelectricstuff suggested for pcb exposure works (Here), approx US$ 2/pcs.

Currently I'm in the progress in building the exposure box, and there is a marking 'BL368' at the lamp, presumably is the indicator that top wavelength is at 368nm.

[MrsR]

Thanks for answering Guys,
My old one had Medical tubes (got them from a local Hospital,a friend was the repair man there)
They were dangerious and only took a 20 to 30 second exposer for CIF boards Positive Type.
I looked at LEDs and at $8.87 ea was going to be expensive.

I have been looking at tube types but could not find an outlet for the right Ballests. the finger nail one looks interesting but I would like to have a max. exposure time of 2 minutes or there about as I work with very fine tracks and mostly 0402 size passives.
SO STILL THINKING of which way to go. Money is very tight at present.

Rachael

[PaulAm]

I have a UV box partially built right now.  I'm using UV LEDs controlled by an Arduino (yeah, I know, yada yada, but the software environment is easy to build and I like C/C++).

I bought a thousand of the UV Leds off of ebay for around $30 and used toner transfer to make the first PCB for the LEDs.

I'm modelling my box after this one:
http://en.elektronicastynus.be/projects/81/

I'm using 4x6 inch boards with 48 LEDs/board.  Four boards top and bottom for a max 8x12 inch double sided exposure area.

[G7PSK]

I have 12 6ft 100 watt arrimed B uv tubes would these do to make an exposure box for pcb's. They are from some medical equipment a bit large but I have often wondered if they would do for pcb exposure, i believe that new they are very expensive and these one have had very little use.

[MrsR]

OK Guys,
I have Ordered 200 5MM Dia. 305 to 405nm at 5000mcd at 3.4 to 3.7volts.
Now where do I go.
Should I make 1 board or split them into2 boards of 100 or 4 boards of 50.
I don't want to get complicated KISS method I think.
I have a filtered power supply 12 Volts 5amps and another one at 10 amps.
I was thinking of placing them in series with just an on off switch.
WILL TAKE ANY GOOD ADVISE>
Rachael

[TerminalJack505]

After hearing about everyone's UV exposure boxes I feel all ghetto with my setup.  I use a couple of bent wire hangers to hold an exposure frame against the florescent lights in my kitchen. 

I don't use this for exposing PCBs, though.  I use toner transfer for that.  I use this method to create a silkscreen mask for my poor man's solder resist (glass paint.)

[PaulAm]

You'll need to do a series/parallel arrangement.  With 12V you won't be able to do more than 3 LEDs in a string.  And I'd put a current limiting resistor in each string to limit the current to 20ma.  Stagger the LEDs so you end up with a uniform illumination.

I use 4 in a string, but I feed the board from a buck converter putting out 14V

[MrsR]

Thanks, I don't know what the Amp pull is, that was the only thing that I couldn't find. I understand what you are suggesting though.
Also thats a neat way to do your silk screens, I use polyester Stencils and a dot matrix printer with no ribbon I draw it up on my CAD program then print a couple out good for printing masks and part types on the PCB. We have a rotery printer also but the boards have to be 8" wide before it works.

Back to the power supply I can go up to 36volts at 10 amps but I wont realy know what voltage or amps I will need till I can get the LEDS and test them.

CHEERS
Rachael

[MrsR]

Well I  don't know if anyone is still reading this thread, here goes.
I was playing arround with some 555 timers in Astable mode when I had a bright idea. If I use the 555 in monostable mode with changing only 1 resistor and a Capacitor I can use it as an ON OFF timer
I can set it up to start stop in 1 minute stages, 1 to 10 minutes should cover it.
All I need to do is put a transistor on the out put to drive a small Relay I can then drive a large relay and switch the 230v AC off and this won't cost me anything as I have all the components in my Bits and pieces shelves
I got the DATA sheet for the LEDS today so I can do the maths and see what or how many leds I can drive per circuit.
I will do all my boards with the Pen Plotter of an old computer again in the bits and pieces shelves.

CATCH YOU ALL LATTER
Rachael