Making a UV light box

[Musicmanager]

Hi
Still very much a novice, learning fast however, thanks to some guys on here.
I want to make myself a UV light box so that I can have a go at etching some PCBs. I've found a Youtube of a guy in China making a light box using UV LED strips in an ABS box which looks ideal but also proves to be a very expensive option. The main expense is the UV LED strips but there seems to be an abundance of 9W lamps for curing Nail Gel and 4W black lamps for counterfeit note machines. My question ? Is a bank of 4 or 6 9 watt tubes sufficient to expose a photo sensitive board in reasonable time or am I missing a trick or two ?
Thanks guys

 

[jpanhalt]

I have seen dozens of similar projects to make UV exposure boxes started, but very few of the builders post results. It may come down to the simple choice: Do you want to build a UV exposure box, or do you want to successfully make PCB's using the photo-resist method?

If it is the former, then there is no end to the complexity you can add. If it is the latter, get a small fluorescent tube fixture that accepts one to three ordinary bulbs, and get started making PCB's. Here is the device I used for many years. Ignore that bulb. That picture is of the original version. I quickly changed to a more common fluorescent bulb. The wavelength you need to properly expose the boards is between 360 nm and around 405 nm. Something around 390 nm is just fine, and many fluorescent bulbs put out at that wavelength. That is one reason you won't find many fluorescent lights in art galleries. The UV bleaches pigments. Some people use ordinary incandescent bulbs, but I have no experience with them. Even if they produce light of the correct wavelength, the heat that is also produced might cause problems.

John

 

[jjw]

Uv led strips may be expensive, but you can buy 5mm uv leds with few cents each.
I made a few years ago a box with 48 ( 6x8 ) uv leds on a 100x160mm board.
The power supply is 18V DC and the leds are connected 4 in series, current limited to 20mA.
It has a count down timer ( PIC18Fxxxx ) with buttons for setting the time, but it is overkill, 555 based timer is good enough.The exposure time is about 4 minutes.

Here is a box made with one power UV led: https://yveslebrac.blogspot.fi/2010/11/single-led-uv-pcb-exposure-box.html