Conductive Paint/Pens

[inefficiency]

Hey guys.

I've been trying to figure out a way to create some PCBs without getting them manufactured, as I'd only want a small handful and not hundreds.

I also don't really want to get into etching with all the acid and stuff if I can avoid it.

So I was wondering if any of you guys have experience with conductive paint and the likes. Would it be possible to make your own boards by painting the traces by hand or possibly by creating a stencil and spraying it on or something?

This is the kinda thing I'm talking about;

http://www.bareconductive.com/

http://www.maplin.co.uk/p/circuitworks-conductive-pen-standard-tip-n73aa

There's probably a lot of reasons why this isn't a good idea, but a bit of discussion never hurts!

[dexxyy]

My main worries with these would be longevity, ie, how long will it last before degrading and also, how precise would you need to be with soldering temperatures? If your iron is too hot will the paint melt or burn? A mate of mine had an old 60's fuzz a few years back, dunno what it was cos all the labels had rubbed off, anyway, the circuit was mounted on thick cardboard with holes punched for the component legs to go through and then the legs soldered together. Something like those, if they worked ok could lend to making circuits on some pretty funky media.

[inefficiency]

Yeah, those were my concerns too. I mean, the pen says that you can solder to it "at low temperatures", but how low is low? If it gets heated up too much could it potentially weaken it and cause it to flake off later?

I just think if there was something like this that was actually suitable, you could make some insane looking boards.

EDIT: The product page for the paint says; "Apply with a brush, roller, or screen print. Leave to dry for 5 minutes, Electric Paint becomes conductive when completely dry."

I love the idea of being able to screenprint PCBs.

[IvIark]

I considered this too but ended up not bothering.  It's a great idea that you could just put something down in pencil and then follow it with the pen but as has been mentioned the longevity and quality worried me.  As long as the circuit isn't too complicated a much better idea is  the rolls of adhesive backed copper strips.  They're sturdy like vero tracks and with a bit of planning you could make totally robust circuits.

Like this: http://www.rapidonline.com/mechanical-fastenings-fixings/3m-scotch-1245-shielding-tape-copper-6mm-x-16-5m-51-2011

[inefficiency]

Yeah there's all that, but a thing that worries me now that I think about it is sound quality. If you have an audio signal traveling through this paint, I can imagine there's a chance of degradation. I was trying to figure out how it works and what it's made of and I'm pretty sure copper is much better :p.

I wonder if you could cover a square bit of material with that tape and then use a scalpel or something to cut a circuit into it and peel off the bits that you'd cut out... Might be a bit of a pain, but I reckon you could find a way.

[Beaker]

I have used those conductive inks pens, and have a pretty low opinion of them. The ink is thin and spreads easily so it''s not easy to draw narrow parallel tracks. It also does not stick well, and  is only really useful if a pad breaks off a PCB.

I have a roll of this stuff for shielding guitar cavities and pickguards.

http://www.ebay.co.uk/itm/EMI-COPPER-FOIL-SHIELDING-TAPE-100mm-x-4m-LOW-IMPEDANCE-CONDUCTIVE-ADHESIVE-/291131937976?pt=UK_Sound_Vision_Other&hash=item43c8d0d4b8

It sticks REALLY well, the glue is itself conductive, cuts easily with scissors, a scalpel or craft knife, and you can solder to it with ease.

I reckon it would be a good candidate for a DIY PCB material, using blank phenolic sheet or fibre board.

I have some fibre board kicking around, so might give this a try if I have time.

[inefficiency]

Thanks for the info Beaker. It's nice getting some feedback from actual experience.

As soon as Mark posted that tape it did remind me of the rolls of stuff folk use for shielding cavities and stuff.

I don't know if anyone's ever tried it before, but I think it could be an accessible way for some folks to create PCBs. You never know, it might end up being slightly less labour intensive than etching.

I guess if you were to do it the way I was thinking, then you'd just need to get the circuit drawn onto the copper and then start scalpeling.

[Beaker]

Yes, I think you are right. Stick the tape to the board, and print out your pcb layout. Place your layout over the tape, draw around the layout tracks with a pen - this will mark the copper tape, so that the tracks are visible. Then start cutting with a scalpel and peeling away what you don't need.

The thing with etching your boards is it is really easy, and takes no more time to etch ten boards instead of one.

This tape method would be fine for one-offs - a pain in the arse for multiples.

[inefficiency]

Yeah, I getcha.

At the moment everything I make is a one-off, so that's the reasoning behind doing it. Getting all the gear to etch and setting everything up just to do one board seems like a bit of a hassle. I'll probably end up investing in the stuff at some point anyway and maybe make 10 at a time just to make it more efficient.

Anyone got any good sites for circuit layouts that I can use to grab a couple of basic ones for testing? Maybe just a little fuzz face or an em-drive or something?