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Help to build a UV box for PCB

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Hy,

I intend to build a UV box and I need some advises

For now I only have a UV tube Philips TL-D 18W/08 T8 590mm UV-A

I think is good for PCB together with another 3 pieces same model as above
in the following configuration

A wooden box, 2 tubes at bottom wired with an electromagnetic 36W ballast and a 2 starters specially designed for 2 tubes (S2 4-22W) and 2 lamps above with another ballast and starters.

What do u think of this? It is OK

A wiring diagram would be **broken link removed**

My question is what about Actinic series from Philips, is it good? I read it also emits light in UV-A range but in smaller quantity than blacklight models from Philips, and they have a white diffuse glass.

Any comment and methods about how to build such a unit is welcomed.

Thank you
 
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Well any list that emits a resonable amount of the high energy UV light can be used. I use a 15W UV bulb with a electronic balast for my Uv box. The box it self is a old printer case with the lamp mounted on the top. The exposhure times are about 8 to 10 minutes. Comercal boces have like 4 to 6 such bulbs and get the exposhure done in a minute or two.
 
Any comment and methods about how to build such a unit is welcomed.

hi,
Line the inside of the box with reflective material, kitchen foil makes a good reflector.

If you fit 3 tubes, space them so that the light falling on the copper side of your pcb is evenly distributed over the pcb area. You dont want bright and dull areas of lighting, that wil give over and under exposed areas.

Choose a strong glass to cover the box over the tubes also a hinged box lid is a good idea.
Use a second heavy glass plate to hold the pcb and artwork firmly into contact.

Buy yourself a clockwork kitchen timer.:)
 
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hi,

just follow Eric's advise for the reflector. You'll achieve best exposure results if the tubes are placed at tube diameter distance or even less.

If you possess an exposure meter you should use it to optimize tube distance.

Special care has to be taken of the glass. Most window glasses filter UV-light. Do not use window glass, but quartz glass.

Boncuk
 
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add a capacitor at the ac mains input to help power factor compensation for the ballast. you might well use an electronic ballast these days
 
What about painting the inside part with a chrome spray can. It will reflect the light I think. What about a mirror?

I saw the capacitor on a Philips **broken link removed** about how to wire 2 tubes to 1 ballast in series together with an ac cap at the mains, a 450VAc 2.7uF for wiring in series
 
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For now I only have a UV tube Philips TL-D 18W/08 T8 590mm UV-A
590nm is orange/yellow in colour, I think you mean 390nm or more likely 360nm.
 
Actinic bulbs for aquariums peak at 420mm. You don't really need any eye protection when working with them, aquarists have been using them over open-top tanks for years.
 
Instead Philips blacklight i wanted to use Actinic BL 18W/10 SLV tubes, these are more cheaper than blacklight 18W and emits more UV-A about 5W, Here is the official **broken link removed**. Maybe i will build a box with these tubes, 4 will be enought
 
Quartz plate is hard to find in some places and quite expensive. Single-strength window glass will pass enough UVA to work. It's what I use.

John
 
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Sorry that was my fault, you clearly stated 590mm, it was me that mis-read it to be 590nm.

That's OK it happens

About the glass, ya quartz glass is very expensive and hard to find so a typical 2.5mm thickness glass would be an appropriate solution but with a little longer exposure time the result it's very good

I decided to put 4 Actinic tubes cause are cheaper and put them at 7cm distance above and beyond the glass so the exposure will be the same on both sides: 2 tubes on one side - 7cm distance and one 2.5mm glass.
On the other part will be the glass that is pressed on the PCB again 7cm distance and 2 tubes

The exposure time will be determined with a PCB test board covering 10% of the board with an opaque black paper every 1 min staring with minute 5
Best exposure will be chosen.

I will not build a timer. The timer will be my phone countdown along with 2 switches, one for tubes above and the other for those beyond, so for one side PCB just switch only the proper tubes. I don't see a reason to add a timer cause when you do PCB you will stay near the exposure unit not doing cooking in that time. But is everybody's choice.

I will post soon a method to expose a double side PCB with a film perfectly aligned

Anyone can give questions and suggestions even post their UV box on this post

Thank you
 
You can use normal glass for UVA, you only need quatz for the shorter wavelengths e.g. UVC.

The 420nm given off by actinic tubes is actually visible violet, not UV but you will get some UV and violet is a short enough wavelengh to activate photosensitive boards.

The best type of tubes to use are insect killer tubes as they produce lots of UVA which is perfecly safe as long as you don't stare at the tubes from a short distance for long periods of time.
 
I've got a bag of 100 UV LEDs here, two identical stripped down scanners which have been mounted face to face and no time to experiment due to a bathroom refit for the next week and a half :(
 
Quartz plate is hard to find in some places and quite expensive. Single-strength window glass will pass enough UVA to work. It's what I use.

John

Hi John,

Cannibalize your scanner and order a spare glass. :D

Hans
 
The best type of tubes to use are insect killer tubes as they produce lots of UVA which is perfecly safe as long as you don't stare at the tubes from a short distance for long periods of time.

Hi Hero999,

try looking into the beam of an UV-radiating LED of Seoul semiconductors for a split of a second. It radiates 70mW at 340nm solely at an angle of 20degrees!

To make it safe order an escourt dog before you do that. A Seoul semi engineer required one month of intense medical care to regain his vision after he ignored the safety precautions.

Hans
 
I was referring to fused quartz that shows a UV cutoff <200nm. I don't think the scanner platten is made of that, as opposed to polished glass that will pass UVA to an extent, but not UVB or UVC. Quartz would be prohibitively expensive for a scanner and of little value, as the bulb is coated to block short wavelength UV. Fisher Scientific has quartz 6" X 6" for about $230. The scanner is 9X11.

Modern rolled window glass does not cause enough optical distortion to matter on the PCBs I make.

John

Edit: Some plastics such as polypropylene and polyethylene, also pass UVA, even UVB, but one must be careful as UV blocking agents are often added to increase UV stability. Data on UV transmission of specific plastics is hard to find. I've tried to get that information for the films I use to make my transparencies, but the manufacturers just will not give it to you.
 
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