Clay PCB?

So I saw this blog post
[blog.reprap.org]

They were speaking of problems caused by the plastic melting.

So what if they basically took an exacto-knife and used the cartesian bot to cut channels into the clay, took it out, fired it (or some clays don't need to be fired iirc) and then extruded the copper or whatever conductive material they used onto the clay sheet.

I don't know anything about clay or pcb, I've never done any soldering but I just had a crazy idea and thought I'd share it

Now firing clay would be really inconvenient for one board but for like 10-20 it wouldn't be too bad.

Good idea! I like the possibilities with clay, and I have a friend with a kiln.

But won't a thin sheet of fired clay be rather brittle? And a thick sheet rather heavy?
Also, how would the material stand up against drilling holes for the components?

I don't know if I can adequately answer these questions, but I think you can make a small box out of abs for the sheet of clay with the top of it remaining open of course. As for the holes I think you might just have to poke holes in it before firing. I was thinking a 5-7mm thick clay sheet, I guess the only way to know would be trial and error. But I think some people would be willing to live with brittle or heavy parts.

I don't know anything about clay so I would suggest you ask someone who does.

I plan on building a reprap sometime this summer if I find job that is.

Maybe another option would be to print the tracks in plastic on a metal/glass plate, and then pour/mold a plaster of paris PCB on top of the plastic. Vulcanize away the plastic and pour alluminum/zinc/copper in to form traces.

in make magazine, there were instructions for conductive play-dough. should be toward the begining.

I'm pretty sure clay can be extruded, but that might cause all kinds of problems when firing if there are bubbles in it.

I'd be initially concerned about the fragility of fired clay (unless it's really thick... However, I image that could be worked around simply by laying in some support material (fiber or something...)

I think clay is a smart option. Perhaps if firing is a bad idea, we could work on a material that was air-cured or chemical cured.

... i have some heat-cured modelling material called "Fimo" whats hardened in the oven at 120°C and isn't so brittle as clay.

Its available in all possible colours and you can mix the colours for all desires.

Maybe its possible to find a solvent for designing a fluid paste from the base material, but then you can search other heat- or UV-cured comercial available pastes, what should be easier to achieve ...

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Viktor
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i think regardingg clays that harden at lower temps like sculpy & fimo if the electronics are going to cause the clay to constantly be over 50 degrees they will eventually become black and really brittle

air hardening clay can go quite hard and strong especially with scaffolding but it cracks and is gets very dusty

maybe an epoxy clay. i have a brand called Apoxy that goes rock hard in half an hour, maybe rolled down on a bed with a CNC cutting at it or the two parts being mixed and extruded out a plastruder type thing. it's like plumbers clay but that hardens in about 5 minutes

wayland Wrote:
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> I'm pretty sure clay can be extruded, but that
> might cause all kinds of problems when firing if
> there are bubbles in it.

Hi Wayland and others, we are currently extruding clay and it works pretty well. Contrary to our and others expectations the printed objects do not explode during firing while they do contain trapped air. This air is both in the mixed clay and inbetween the traces of the print. Seems like the objects are thin enough so the water vapor can release when you fire slowly, its not the air thats a problem its the trapped watervapor.

The process is documented at unfoldfab.blogspot.com

I know something about ceramics and nothing about PCB's so if anyone can send me a file to test I will print a few copies, fire them and send them back.

Ps. we did a project this week that involved laser cut ceramic green sheets, could be of interest too.

That's really cool that you guys got extruded clay to work. I guess I'll put it on my to-do list!