DissolvPCB enables fully recyclable 3D-printed circuit boards with liquid metal conductors

Huh. So maybe we will one-day get robots that bruise and bleed liquid metal when cut.

Jokes aside, this is really cool and I'll be showing this to my local fab lab.

Oh this is wonderful! I strongly recommend reading the preprint, really enjoyable: URL

This is not just one of those ivory tower papers with their actual applications far away in time and eventually ending up in some obscure industrial process never heard of again in lay circles; this could have an immediate impact on the maker culture and makerspaces right now and in the near future. The preprint describes the process in a very understandable, digestible manner and provides actual implementation examples, as well as detailed recipes for all of the compounds. If you are even remotely interested in the subject matter, I'd recommend you to try it out for yourself. The "ingredients" are all easily obtainable and handleable. Yes, gallium and indium might be a bit expensive, but it is worth it imo. They literally used consumer kitchen equipment for some of the steps, to demonstrate how this is feasible for tinkerers, makerspaces and prototypes. No expensive machinery required (except for an FFF 3d-printer, of course).
- I skimmed through the paper, and I agree that it looks pretty damn digestible for the average tinkerer to understand and implement themselves if they so choose
  But just kind of a quick summary for people who still won't read the article
  You basically 3d print a circuit board out of PVA (which is ~~basically the same material as regular white elmers school glue, so~~ EDIT: that's not quite right, see below non toxic and water soluble) with hollow channels instead of circuit traces.
  Then you fill those hollow tubes with the gallium/indium mix, which has a very low melting point, like "glass of warm water" low.
  Insert any components you need and secure them into place with a drop of glue, and BOOM you've got a circuit board.
  And when you're done, just dump it in a glass of water. The PVA dissolves and you can fish out the metal to reuse in a different project.
  Like you said, the only "specialized" equipment you need is a 3d printer that can handle PVA filament.
  Not necessarily something that's going to be useful for any industrial production applications, but this could be huge for hobbyists and even prototyping for businesses. Most traditional methods for making a PCB call for some kind of nasty chemicals and they're not really reusable, especially not for the home-gamer, this could make for a nice step-up for the people who don't want to deal with this and want something a little more polished than a breadboard or a mess of soldered wires
Direct metal liquid contact from pin to pin! I love it.
(Not to mention how satisfying it is to get a pile of undamaged ICs after recycling)

I wonder if you could use HIPS instead of PVA. Still dissolves, but in limonene rather than water, so inadvertant exposure on a rainy day wouldn't ruin your circuit board. At the same time, the metal should still be recoverable unless there's some chemical reaction between gallium and citrus oil that I don't know about.

As long as i can fill a super soaker with limonene for the inevitable robot uprising, you have my vote
- Amazon will sell it to you in 55-gallon drums (that's >200 litres) if you're willing to pay. That'll fill plenty of super soakers. So it depends on how serious you are about your anti-robot-uprising prep.

I'm curious about the durability of these PCBs. They would be good for prototyping but how well would they handle high humidity environments?

You might be able to coat them, but for long term applications I think you'd be better off etching FR4 the old fashioned way. This sounds like a huge breakthrough for low cost rapid prototyping, though.

PVA probably really limits the applications but that's super cool

I don't see why you couldn't just use a different material if you wanted a more permanent solution. A resin printer is likely ideal to get good accuracy.

Very cool, though JFC there's no way MY printer will be fine tuned enough to generate the channels. The whole process reminds me of the rednecks who pour molten aluminum down fire ant hills, in a good way. The sealing with glorified Elmer's glue is also clever.

Now all that said, you wouldn't want to make anything that's going to have much contact with water, so a lot of typical applications are risky: "My PCB is leaking!" I do wonder if you could do the same thing, but less immediately recyclable, with PLA and a 3D pen.

That is crazy good... if all I need is to get a pcb heater and learn how to surface mount to print someone's custom board, it really opens up the possibilities of open source electronics.

Ooooooooo