building an electric circuit from paint

Most metal oxides are actually quite good insulators, but there is such a thing as conductive paint - it's loaded with actual metal granules, and so looks like metallic paint. I don't know what the base is (oil, latex, ?...) although it probably varies by manufacturer and stuff.

But with conductive paint, you can paint working circuits - then you could paint over them for color and actual electrical insulation in case it will be handled.

But you'd have to use real components - I wouldn't get too excited about trying to make semiconductor junctions out of any kind of paint. :-)

And for complicated circuits you'd have to paint on both sides of the canvas. ;-)

Have Fun! Rich

I do believe Princeton professor Steve Forrrest was involved in the field of silk screened circuits with organic transistors and such. Also some work at Kodak and [Lucent] Bell Labs.

Later...

Ron Capik

To be able to get repeatable results, manufacturers would have to controlled their processes for those properties. Alas...

...not to mention that as soon as you expose the product to air, you contaminate it.

are metallic oxides[...] Some of them[...]have n-type and p-type

You missed a big point: ...WHEN PROPERLY DOPED. It is the *impurities* in the CRYSTALLINE lattice that gives them the desired properties ...and these must be CAREFULLY controlled.

In short, you are up against the same problems as the guys who invented the first transistors: Process technology must be exacting to get usable results.

As Rich said, there are conductive inks. ...which leaves the question: "How will you connect any *devices* to these *conductors* to accomplish anything?"

That's one of the holy grails of development today - get rid of copper traces and let an ink jet make the circuitry. It is even being done on cheap electronic devices like remote controls.

To bridge the traces and avoid jumpers and two sided etched boards - they shoot down a spray of lacquer through a mask to insulate traces then follow that with a bridging compound high in carbon.

Every metallic oxide I know about is a very good insulator, but copper, silver, gold, carbon, and even some aluminum paints are reasonable conductors.

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Sounds interesting. Tell us more about printing circuits with ink jet printers. Are there commercial conductive ink cartridges available? How do you attach components and connect to them. Do you have any information on this?

In message , Bob Eld writes

Kind of jumping on the bandwagon here but some of the RFID tags use a printed antenna, IIRC Elektor electronics gave away a sample of one a few months back, you could try

and search the back issues for more details, it may lead you somewhere.

--
Clint Sharp

This isn't consumer technology it is an industrial technique. And, it should be noted, that it is only practical in something where the current requirements are very low - like the switch matrix on a remote

- where 300 ohms is as good as a dead short. I'd guess that the speed and conductivity is too low to be in competition with copper for most applications.

On remotes they leave a bare copper pad and spray the conductive paint to that - no components are connected that way, just board jumpers.

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Bob,

You might want to check around in the Homebrew_PCBs group, at

. This has been discussed, there, several times. I don't know if it was ever successfully done. But the people in that group do now seem to have good ways to print an etchant-resist directly onto a bare PCB, with inkjet printers.

- Tom Gootee

Well yeah, I was thinking of making an/some insulation layer(s) from non conductive paint if the circuit will become to complicated. :P

Paint like this?

You can't add some colour/pigments to it without ruining the conductivity right?

Good one!

Plastic transistors developed

A team of Bell Labs researchers-Howard Katz, V. Reddy Raju, Ananth Dodabalapur, Andrew Lovinger, and chemist John Rogers-present their latest findings on the first fully "printed" plastic transistor, which uses a process similar to silk screening. Potential uses for plastic transistors include flexible computer screens and "smart" cards, full of vital statistics and buying power, and virtually indestructible.

That or something like it, at least that's what I was talking about.

I don't know the answer to this; you'd have to ask the manufacturer, unless somebody else chimes in. :-)

Cheers! Rich

Hmmm.. Yes. For the manufacturers the flawlessness and exact right mix of silicium/germanium... with their inpurities/doping is essential to make the material predictable and reliable for the mass production process.

But in my experiment the reliability of the material is not that important. Don't get me wrong, the goal is to let the circuit work but it's going to be a crude one, hand made and only one production piece.

Can you explain this a little more please?

Aha... So semiconducting works only when the material has a very high chemicaly purity with a perfect crystal sructure?

And by grinding it to powder and add some medium for viscosity the semiconducting properties will be nil.

Maybe some of these links will help:

Good Luck! Rich

uhmmm... If you want to make a working circuit you also need a insulator? Insulator as a resistor?

I don't get your meaning - in the example they use a layer of lacquer to isolate (insulate) the sprayed on conductor from the ones below it.

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Alot of PC keyboards are made in a similar way. My old Microsoft "natural" keyboard got some rootbeer spilled in it,and when I took it apart to clean it,I found most of the 'traces' eaten clean off of the plastic film "circuit board"..it was hopeless.

It basically looked like they used the same "ink" used in those conductive circuit-writer-pens. A silvery stuff.This was all laid down on a thin sheet of plastic (like overhead projector transparencies.) Three sheets total,two with the "circuits" laid on them,and the third inbetween,with a hole cut out for each button/set of contacts,just enough space to insulate them,until you apply pressure.

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--- There are quite a few electrically conductive metallic oxides:

The most common, I suppose, is indium tin oxide which is used for the transparent electrodes in LCDs.

-- JF

I've heard people fix print plates circuits with a pencil (carbon)?

A friend of mine built a layout of variable resistors using pencil lines (graphite which is a form of carbon) on paper and paper clips. It "worked" as long as you held your breath around it (it was very "touchy").