Simple UV lightbox for PCBs

 by Tvmender
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How to make a simple yet professional looking UV lightbox for PCB production.

With a few items salvaged and picked up in car boot sales you can make an effective PCB exposure box for less than half the price of the cheapest commercial boxes. I have made four of these units (some double sided) yet still use the first one I made nearly ten years ago!

I have decided to update my old battered box with a snazzy new one and thought it would be a good idea to share my experiences.


 
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Step 1: Basic materials

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The basic materials and tools you will need are:

A metal clad tool case (Maplin, B&Q, tool shops - see photos). 
 
Perspex sheet 3mm thick and the size of the inner rim of the lip of your box (see photo later).

M3 Nuts, bolts and washers (20 or so will cover it).

Black card sheet (A3 size, Staples).

2x UV-A tubes - not blacklight tubes, you need to get the right ones (Rapid, CPC, Specialist).

Tube "U" clips to fit the tubes - metal sprung type.

Mains rated switch (Maplin, Rapid, CPC etc...).

Mains flex 3M or so, 3 core 5A (to use whole and stripped into conductors).

Heatshrink tubing slightly larger than the wiring you will use (inner conductors of mains flex).

Ring terminals.

3A Terminal block or "chocstrip"

Mains strain relief cable gland (Maplin, electrical supplier) to fit your mains cable.

Various short screws, pan head and countersunk self tapping.

Sticky tape

2 small blocks of wood 1"x1"

Mirrored card/plastic or tin-foil.

Tools:

Drill.

Drill bits.

Soldering Iron.

Solder.

Crimp tool for ring terminal.

Small flatblade screwdriver

Cross blade screwdriver

Wire cutters.

Long nose pliers.

Pliers.

Knife or scalpel.

Vacuum cleaner.







patrickleephoto says: Jul 29, 2010. 3:55 PM
[2x UV-A tubes - not blacklight tubes, you need to get the right ones (Rapid, CPC, Specialist)] Where do you get these correct UVA tubes? Thank you. Patrick
Tvmender (author) in reply to patrickleephotoAug 1, 2010. 10:54 AM
Hi Patrick, I ordered mine from an electronics parts supplier as a replacement kit for a commercial unit they sold. I am not sure if you are in the UK or US but if you are in the UK then try www.rapidonline.co.uk order code 34-0709 for "actinic UV tubes" but as for a US supplier I am not sure! I have been told some aquatics centers may stock them but I am not sure. Hope this helps! - Sam
thegrovesy says: Nov 28, 2012. 5:28 AM
Excellent work, nice and easy to understand. Just one question, does the box get hot when its in use? Thanks
Tvmender (author) in reply to thegrovesyNov 28, 2012. 9:29 AM
Hi thegrovesy

My box didn't get warm at all. I suspect that with prolonged use the ballasts may get warm but never hot.

Thanks for the comment!
Tvmender (author) says: Nov 28, 2012. 9:28 AM
Hi thegrovesy

My box didn't get warm at all. I suspect that with prolonged use the ballasts may get warm but never hot.

Thanks for the comment!
DillyDog says: Jan 28, 2010. 6:32 AM
Some of you may be interested to know that I am currently working on a timer for this very purpose. It is PIC controlled with an LCD readout and memory functions. If anyone is interested, leave me your email addy and I will contact you.
necostefan in reply to DillyDogJul 26, 2010. 11:01 PM
Here is my email: necostefan@yahoo.com
rpcook says: Jan 28, 2010. 8:34 AM
Nicely done!  Thank you.
Tvmender (author) in reply to rpcookFeb 1, 2010. 3:05 PM
Thank you too for viewing my first instructable! Glad you liked it.
rushourgraffic says: Jan 29, 2010. 10:10 AM
you could add a safety interlock switch near the back of the box through the plastic panel. A normally open monetary contact switch rated the same as your mains switch. that way when you open the box (or some unsuspecting person who knows no better) you wont get any UV in your eyes.
JellyWoo says: Jan 28, 2010. 6:01 PM
 I'm sorry but what is a UV lightbox used for?
SmAsH! in reply to JellyWooJan 28, 2010. 10:06 PM
Mainly etching uv sensitive pcbs. But they have other uses too...
Wiki it.
Wragie says: Jan 28, 2010. 5:15 PM
Used almost the same parts a few years ago but had a switch for the lid and used a mechanical power timer used in dark rooms. Also used a nice new red metal tool box that was on sale for $4. Hardest part is sourcing the UV tubes.

Sure is nice to erase the proms in 3 mins or less. Even had a few 'dead' ones come back to life.

kea says: Jan 28, 2010. 8:54 AM
Re UV light box, The first one used 2 UV INCNDESCENT type bulbs the inside of the box got so hot it cracked the glass!.

MK 2 light box used 2 COMPACT FLOURO TUBES these run nice & cool & dont require ballasts. I use the Kinsten Photo board & it works very well.
I found IRON & PEEL does not always work, also some of the tracks come away.  THE PHOTO METHOD IS THE BEST &QUICKEST WHEN USED with the Hydrogen Peroxide &Hydrochloric acid, AKA SOLDER FLUX.
Cheers John M
mweston says: Jan 22, 2010. 5:40 PM
 As a safety precaution you could wire up a reed switch (think relay connected ballast power source) and glue a magnet to the box lid. 

If you forget to flip off the switch, the light would shot off upon opening. This might not be the most practical feature, but better safe than sorry.
Tvmender (author) in reply to mwestonJan 23, 2010. 8:03 AM
Thats a good idea, most of my boxes do have a safety interlock. Its one of the improvements to the design you could make in step 14 but would probably be a good idea to include it...or wear welding goggles?! :P

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