DIY UV Exposure box with UV LEDs

Nordic · 2nd October 2006, 06:48 PM

I'm still busy bribing my friend to bring his digital camera, so I can get better pictures, but I'd just like to share the concept... planting th idea is enough to get you going...

I still have to add the timer circuit, but needed to check what exposure was needed first... 2 minutes works pefectly.

there are 6 branches with one 120R and 2 5mm UV LEDs each driven off a 12V supply.

The LEDs are not lit in the photo.. they are just reflecting the webcam's infrared beam.

I_Forgot · 2nd October 2006, 08:26 PM

Will UV leds produce enough light at a short wavelength to do the job?

I_F

Nordic · 2nd October 2006, 08:46 PM

Absolutely!

Nordic · 2nd October 2006, 11:40 PM

Ok I just figured out how to operate the focus ring on the cam.. will take pictures in the day tommorrow...

Nordic · 3rd October 2006, 08:22 AM

this pcb was made with a black marker

djQUAN · 3rd October 2006, 08:43 AM

you could file the front of the LED's flat so that the light coming off them would be more even.

es44 · 3rd October 2006, 08:50 AM

This is a thread i will follow with big interest.
Nothing lees than genius is the word that comes to mind

Thanks a lot for sharing this one, looking forward to hear about experiences with it in practical use.

Best regards
Ebbe

Nordic · 3rd October 2006, 08:54 AM

probably, I used a piece of paper to determine the optimal distance by looking at the light pattern through the page. Got it so, that all overlap, and it realy works very well. It is only sized for half Eurocards , maye up to 10 x 10CM (4 x4").
But I plan to add 2 of the panels to give me 20 x 10cm, and I might play with the spacing as it works exceedingly well now... might get even more footprint out of it... the majority of PCBs I make, will fit with no problem...

Thijs666 · 3rd October 2006, 11:09 AM

Check Elektor-Electronics, may 2006. They have a nice article about this!

Elektor-Electronics
Direct link

Nordic · 3rd October 2006, 11:28 AM

Yeah , thats where I got the idea.. was too cheap to pay for the article... so I just looked at their PCB and worked it out for myself from there....

Instead of the silver foil , I just soldered the LED's on the coper side of the PCB to use as a reflector...

Did my first exposure last nigth and it came out realy nicely, except for me mixing the caustic soda too strong... luckily it was spray on photoresist so I can use the board again... But I could clearly see that it was working 100 times better than the sunlight method I used, and appart from the size restriction, it works 100%.

lemme know if you need a circuit diagramme... in retrospect I could have added the timer circuit on some of the unused copper areas.. but luckily it should be small so I can just glue it somewhere inside the case...

The LEDs were not quite as cheap as I hoped, but at least it is alot more durable than glass tubes and bulbs and should have a much longer and maintenance free lifespan. Total project cost +-$30.

If you are even thinking of makeing PCBs I can suggest this method, before trying any of the others I did before.

The total process is...

Lay out in eagle or obtain image file for pcb from someone.

Save it on a disk (yep its africa, the print shop has no usb port).

Drive to the print shop, and have them print it on acetate (tranparency), for which they charge me about 50c US. Which is a bargain considering how many sheets their printer mangles before it gets it right.

You can only smile and go with the flow sometimes...

I then come home, cut the printout closer to size so I don't have unsupported pieces lifting against the rest during exposure.. i.e. just cut out the outline a bit larger than the board...

Put glass from photoframe on UV box
place the transparency on it (make sure you got it the right way around)
Place the PCB on top of it

power UV LEDs for 2 minutes

remove pcb and rinse exposed photoresist with caustic soda (from your local hardware shop - its basicaly draincleaner , comes in white flakes or balls and is about $1 a small bag) and WARM water. -mixture (7g to 1l)

stick PCB under a cold running tap for a minute

drop pcb in luke warm Ferric chloride and water mixture (available from electronics shop normaly about 3 dollars for a 500g tub) You can reuse this mixture, I don't know how old mine is, I just add some hot water everytime I use it, and it stands in an open container from which water evaporates to counter filling...

Run under cold tap again. and finaly whipe off the remaining photoresist from the now completed traces with some acetone and kithen towels and you are all done....

2nd October 2006, 06:48 PM	#1
Nordic diyAudio Member Join Date: Sep 2005	DIY UV Exposure box with UV LEDs I'm still busy bribing my friend to bring his digital camera, so I can get better pictures, but I'd just like to share the concept... planting th idea is enough to get you going... I still have to add the timer circuit, but needed to check what exposure was needed first... 2 minutes works pefectly. there are 6 branches with one 120R and 2 5mm UV LEDs each driven off a 12V supply. The LEDs are not lit in the photo.. they are just reflecting the webcam's infrared beam.

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2nd October 2006, 08:26 PM	#2
I_Forgot diyAudio Member Join Date: Jan 2005 Location: Phoenix, Az.	Will UV leds produce enough light at a short wavelength to do the job? I_F

2nd October 2006, 08:46 PM	#3
Nordic diyAudio Member Join Date: Sep 2005	Absolutely!

2nd October 2006, 11:40 PM	#4
Nordic diyAudio Member Join Date: Sep 2005	Ok I just figured out how to operate the focus ring on the cam.. will take pictures in the day tommorrow...

3rd October 2006, 08:22 AM	#5
Nordic diyAudio Member Join Date: Sep 2005	this pcb was made with a black marker

3rd October 2006, 08:43 AM	#6
djQUAN diyAudio Member Join Date: May 2004 Location: manila	you could file the front of the LED's flat so that the light coming off them would be more even.

3rd October 2006, 08:50 AM	#7
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	This is a thread i will follow with big interest. Nothing lees than genius is the word that comes to mind Thanks a lot for sharing this one, looking forward to hear about experiences with it in practical use. Best regards Ebbe

3rd October 2006, 08:54 AM	#8
Nordic diyAudio Member Join Date: Sep 2005	probably, I used a piece of paper to determine the optimal distance by looking at the light pattern through the page. Got it so, that all overlap, and it realy works very well. It is only sized for half Eurocards , maye up to 10 x 10CM (4 x4"). But I plan to add 2 of the panels to give me 20 x 10cm, and I might play with the spacing as it works exceedingly well now... might get even more footprint out of it... the majority of PCBs I make, will fit with no problem...

3rd October 2006, 11:09 AM	#9
Thijs666 diyAudio Member Join Date: Nov 2003 Location: Maastricht	Check Elektor-Electronics, may 2006. They have a nice article about this! Elektor-Electronics Direct link

3rd October 2006, 11:28 AM	#10
Nordic diyAudio Member Join Date: Sep 2005	Yeah , thats where I got the idea.. was too cheap to pay for the article... so I just looked at their PCB and worked it out for myself from there.... Instead of the silver foil , I just soldered the LED's on the coper side of the PCB to use as a reflector... Did my first exposure last nigth and it came out realy nicely, except for me mixing the caustic soda too strong... luckily it was spray on photoresist so I can use the board again... But I could clearly see that it was working 100 times better than the sunlight method I used, and appart from the size restriction, it works 100%. lemme know if you need a circuit diagramme... in retrospect I could have added the timer circuit on some of the unused copper areas.. but luckily it should be small so I can just glue it somewhere inside the case... The LEDs were not quite as cheap as I hoped, but at least it is alot more durable than glass tubes and bulbs and should have a much longer and maintenance free lifespan. Total project cost +-$30. If you are even thinking of makeing PCBs I can suggest this method, before trying any of the others I did before. The total process is... Lay out in eagle or obtain image file for pcb from someone. Save it on a disk (yep its africa, the print shop has no usb port). Drive to the print shop, and have them print it on acetate (tranparency), for which they charge me about 50c US. Which is a bargain considering how many sheets their printer mangles before it gets it right. You can only smile and go with the flow sometimes... I then come home, cut the printout closer to size so I don't have unsupported pieces lifting against the rest during exposure.. i.e. just cut out the outline a bit larger than the board... Put glass from photoframe on UV box place the transparency on it (make sure you got it the right way around) Place the PCB on top of it power UV LEDs for 2 minutes remove pcb and rinse exposed photoresist with caustic soda (from your local hardware shop - its basicaly draincleaner , comes in white flakes or balls and is about $1 a small bag) and WARM water. -mixture (7g to 1l) stick PCB under a cold running tap for a minute drop pcb in luke warm Ferric chloride and water mixture (available from electronics shop normaly about 3 dollars for a 500g tub) You can reuse this mixture, I don't know how old mine is, I just add some hot water everytime I use it, and it stands in an open container from which water evaporates to counter filling... Run under cold tap again. and finaly whipe off the remaining photoresist from the now completed traces with some acetone and kithen towels and you are all done....

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