Making PCBs using UV sensitive board

[Aharon]

I thought I would give this a try and I'm going to share what I have so far and ,maybe someone can help me with some advice too.

I went to the local recycle center and got a large old scanner and a couple of fluorescent light fixtures.Total $8.
Gutted the scanner and placed the fixtures inside secured with double sided tape for now but screws later when I know the exact possition I want them in.
The scanner guarantees the glass is UV transparent plus is a cheap quick box.
All I have to do now is buy the black UV tubes(probably at a pet store if I can't find them somewhere else) and I'm ready for my first PCB in this manner.
The scanner also provides the lid to put on top of the transparency and PCB to hold them down while exposing.
So far it looks cool,let's see if it works.
This method reportedly is more precise,better quality and the only extra (aside from the box) is the developer which costs about the same as the ferric chloride.
I'll report back when I make my first PCB this way which will be probably the Sans Amp.
Funny story with this pedal.
I had built it and worked amazing.No problems untill I decided I had to fit it with a 9V plug. Lazy that I am and so sure of my skills having made 30 boxes already went on to drill "carefully" with the circuit inside,just a hole I said to myself and then solder the leads,5 minutes tops.
As I proceeded to drill,the bit got caught in the box, spun the drill and everything around it including the Sans Amp sending shrapnel and pieces all over the room.I swear not even the pots survived and my wrist barely.
Moral of the story,never underestimate the problem or overestiimae your skills.(LOL)Sorry for the rant.
Aharon

[gez]

The scanner also provides the lid to put on top of the transparency and PCB to hold them down while exposing

.

Aharon, if you're using UV tubes and there's any light showing when the lid is down, wear some eye protection or avoid looking at the light source.  Obvoius, I know, but easily overlooked.

So far it looks cool,let's see if it works.I'll report back when I make my first PCB this way which will be probably the Sans Amp.
Funny story with this pedal.

Do plenty of tests beforehand on samples.  Don't expect to get it perfect on your first attempt.  When you do get it right though, results are excellent.

I just bought a new exposure box and it took at least four attempts on bits of scrap board until I got it right.

Here's one of my recent boards



Laser printers give better results, but this is good enough for me (inkjet toner on a transparency with tracing paper covering it to make it more opaque)

[Aharon]

Hi gez.Thanks for the tips.Nice results you got!.
Yeah,I expect a couple of duds before I get it right much like with PnP when I started.
So to make sure: you print on a transparency and put a piece of tracing paper between the transparency and the board to make it more opaque?.

Also,are you using the 600 series pre-sensetized boards from MG Electronics,how long did you expose for?.

By the way Home Depot carries the black fluorescent tubes in 18" size if anybody is building one of these.
Cheers
Aharon

[spongebob]

A few days ago there was a how-to-make-your-own-pcb thread at diyaudio.com, was very informative (for me at least, still stuck at stripboard :wink:), maybe this is of some help:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=38283

[gez]

So to make sure: you print on a transparency and put a piece of tracing paper between the transparency and the board to make it more opaque?

Almost, I place a sheet of tracing paper/greaseproof paper on the glass of the box first, then overlay the transparency so that the ink side is in contact with the board (I use ordinary cheapo transparencies intended for use with an inkjet) and expose.  This way ensures that there are no gaps for light to get under, which will eat away traces.

The board I get in the UK seems to all come from the same supplier (don't know who though, probably Mega Electronics) and takes 2.5 mins to expose, 30 seconds to develop then you just etch in ferric (rinse off the developer first).  Different board needs different amounts of time (your supplier should have info, or there'll be a sticker on the board telling you how long you need to expose it for).

You might have to experiment with different types of tracing paper.  Most work fine, but some greaseproof paper (the yellow stuff) doesn't work very well - it's too opaque and you get swirly patterns that don't etch.

By the way Home Depot carries the black fluorescent tubes in 18" size if anybody is building one of these.

I've never used these, most exposure units seem to have the tubes that get used in sun beds.  If flourescent lights work though, the black bulbs should work (might need to expose for longer).

[Mike Burgundy]

I actually use a face-tanner and regular glass - works fine. Putting it all in a scanner is very smooth, though.
If the board isn't too detailed and your lights are strong enough for a very quick exposure (I need just seconds for transparancies) you can get  away with a regular 80-grams sheet of paper and a deskjet set to heavy toner.  Takes about 20 seconds. Works nicely, and saves time

[Aharon]

Great info!.Thanks to all.
Aharon

[Aharon]

Found this link,I meant to say MG Chemicals not Electronics.There's a video too.

http://www.mgchemicals.com/techsupport/photo_inst.html

Aharon

[gez]

I don't know about the States, but in Europe you can get 'safe' developer (non sodium hydroxide) and it allows you to leave the board in the solution up to 30 X longer (if you forget).  It's made by Seno.

Didn't read all of the link, but it's pretty bog-standard stuff.  Might sound a bit complex, but once you've got the method down you can churn out boards really quickly (especially if you need more than one).

Once you've etched your board you can remove the remaining resist with Acetone/nail-polish remover.

[gez]

Once you've etched your board you can remove the remaining resist with Acetone/nail-polish remover.

Ah, I see from the literature that this isn't necessary with this particular board - nifty feature!

[Aharon]

Yet another tutorial,this one includes which tubes are the best and suprise it's not the "real" UV tanning lights,it's the black fluorescents because of the wavelenght.Go figure.


http://www.reprise.com/host/circuits/ecb.asp

Aharon