Make Copper Formate (for Making Copper Conductive Ink)

Make Copper Formate (for Making Copper Conductive Ink)


Warning: Copper sulfate and formic acid are poisonous. Wear gloves when handling them. Greetings fellow nerds. Some years ago i made silver conductive ink. A liquid that when applied to a surface and then heated would decompose into metallic silver that was conductive. A number of electrical engineers have asked if there was a copper analog of the same substance. While it’s not an exact analogue, in this video we’ll make copper formate, a useful precursor to copper conductive ink. We first start with 65g of copper sulfate pentahydrate. This can easily be bought as root killer, or a pond algae control chemical in garden stores. You can also make some as i’ve shown in earlier videos. Now we add in 250mL of water and stir until dissolved. This is going to take awhile. Now in a separate container we get 33g of sodium carbonate. To this we add 150mL of water and stir until dissolved. You can also use sodium bicarbonate if you adjust the stoichiometry. But i prefer sodium carbonate for this since it dissolves more than sodium bicarbonate. Now we add both solutions together. What we’re making is copper carbonate hydroxide, sodium sulfate, and carbon dioxide gas. It’ll bubble a lot so it might help to stir it and keep it from overflowing. It’s pretty thick at first but as it reacts i find it thins out somewhat. When the bubbling stops, the reaction is finished and we can now filter out our copper carbonate hydroxide. Wash out the containers with water for quantitative transfer. Also wash the precipitate with generous amounts of water to wash out the byproducts and impurities. You can let it dry on the filter paper if you want but i’m going to use it directly as is. We transfer the wet copper carbonate hydroxide paste over to another container and wash down the filter paper with some water for a total volume of about 200mL or so. To make copper formate we add in formic acid. I’m using 32mL at first of what i thought was an azeotropic mixture of 77% We made this formic acid a while back from glycerol and oxalic acid. Anyway, stirring and turning on heating helps to drive the reaction forward. The formic acid reacts with copper carbonate hydroxide to make copper formate. Now I thought it would all react but when it did not i thought i didn’t have enough water so i added more. Turns out I was wrong as it still wasn’t reacting so i added in another 20mL of formic acid. Now it all reacts. My formic acid must have been very dilute. I’ll probably have to go back and fractionally distill it again. Anyway, let it cool and evaporate down to 100mL of volume to get crystals. I don’t recommend boiling it down as it will decompose. I also didn’t let to evaporate dry since i want the soluble impurities to remain in solution. Now we filter out the crystals. Give them a wash of ethanol then let them dry on the filter paper. And there it is copper formate tetrahydrate. So what can we do with this? If you get a solution of it and heat it up past 200 celsius the copper formate decomposes into copper, carbon dioxide, and hydrogen gas. Now the copper produced isn’t anywhere near as solid or high quality as what was produced with silver conductive ink. As you can see i can get brief flashes of conductivity, but nothing reliable. The particles don’t seem to be all that well bonded. But i’m hoping this low level copper is still good enough for something called through-hole plating. A process electrical engineers use to make printed circuit boards. But i’ll cover that in an upcoming video. Even if this can’t be used as-is, copper formate is still a good precursor to copper conductive ink since it does indeed generate copper. In fact in the literature there are chemical additives that make it viable. I’ll see if i can find an amateur solution. If i’m successful i’ll make a video on it. Thanks for watching. Special thank you to all of my supporters on patreon for making these science videos possible with their donations and their direction. If you are not currently a patron, but like to support the continued production of science videos like this one, then check out my patreon page here or in the video description. I really appreciate any and all support.

97 Comments

  1. As a 1st year electrical engineering student, I appreciate how some of your videos bridge the gap between chemistry and electronics.

  2. For a split second, I got formate and fulminate mixed up, so I got really confused why you wanted to use it as a conductive ink!

  3. I don't know why it struck me in this video but I never really think of the vital role water plays in chemistry. I guess because I can drink it, I don't really think of it as a solvent or otherwise chemically interesting.

    Do you think the boiling action of the solution created the voids in the resulting copper? Would it be possible to evaporate it then heat it (not sure if the heat is necessary for it to convert to metallic copper)

  4. Thats the problem with this series of metals. Though they can form cohesive structures with themselves, they tend to want to form particles rather than a plating without some sort of extra charge to guide their formation. There are a few things you could try, like charging the surface to be plated and dragging the cathode over the surface, but thats no different from standard electroplating. The other thing could be is to manipulate Cu ions in solution, let it dry and reducing them by dipping the surface in a reducing agent. The last techinque that comes to mind is to acid etch the surface so the copper particle settle into the micrscopic valleys.

    Getting copper to bond with itself as a solid without electrocatylitic techniques as you can with the mirror demo isn't anything I've ever heard of, and may require much slower decomposition rates than seen in the video, but is still likely to be too porous and brittle to be useful.

    If you can think of a way to form stronger bonds between the copper particles, this decomposition process has some promise, otherwise i think its just a novelty.

  5. That's such a nice shade of blue, matches my state of mind, but the doc put my pill dosage up so I'm good… 😛

  6. I rarely understand what's happening but it's still cool to watch. Maybe someday I'll try making copper sulfate crystals as a display piece.

  7. Neat! Is there much that can be done to make lower resistance tracks? Have you also considered trying your hand with Graphene? There are a lot of videos about making it. Would be interesting to see a chemist's twist.

  8. Awsome! I made this when I was 12 but I jusz added 80% formic acid straight to copper sulphate. It is insoluble in the little amount of water used so when formed it just percipitated out.

  9. Could we get a video of this done in a police station? To ensure it's not meth? I'd like to see a copper forming copper formate.

  10. Would it perhaps work better(e.g. form a better conductive path) if you were to let the evaporation occur more slowly? I could imagine the speed of copper formation could influence crystal size and therefore the conductivity between the crystals/pieces…

  11. the way you made the formate of copper can be used to prepare almost every salt of copper by starting with cuso4 and the acid of the corresponding salt. I personally made copper chloride through this way. Also if fine cu powder is needed for being used as a catalyst this formate salt works great. love it

  12. I've been playing around with trying to make something like that for a while now, without success.
    How small are the Cu particles? Can they be suspended in water or acetone, or are they too big and settle out too fast?
    Usually commercial conductive inks use incredibly tiny metal particles suspended in a solvent along with some kind of binder.
    Finding the right binder and how much of it is where I'm stuck.
    Either the particles don't stick together, or the binder is too much and there is no conductivity at all.

  13. Since you have a phd in anorganic chemistry I want to ask you a question: There a two types of copper carbonate hydroxide: one is more blueisch the other is more greenish the internet sasys that the blue type is actually Cu3(CO3)2(OH)2 and the green Cu2CO3(OH)2 when you heat the blue type in water it forms the green and my experiments show the same result but when making the carbonate it is blue all the time. is it just stöchiometry or something else which effects the outcome?

  14. Is it possible to use the copper formate as a kind of filler for the silver? And if so how well would it conduct electricity

  15. I have lots of enamel (magnet) wire in bits and pieces.
    Is there a cheap and simple process to make a pure solid copper nuggets through chemistry/electrolysis?
    I was thinking of dissolving it in battery acid and then electroplate a pure copper wire until its nice and thick.
    any ideas?

  16. I guess the problem is that copper particles at 200C are going to oxidize very rapidly, the opposite of what happens to silver… Maybe you could use some organic that will act as a reducing agent as (or after) the copper forms… like how acetone reduces hot copper. Also, I'm curious how a mixture of this and the silver diamine formate would fare. LOVE YOUR VIDEOS!

  17. You could add some graphite powder to the formate solution to make a suspension and then heating all up. You would get some nucleation sites and the graphite being conductive on its own could help coat and bridge the gap in between individual copper metal bits. Maybe a bit of TiO2 for similar reasons. In both cases it would not take all that much to get the desired result, maybe a few tenths of a percent to a few percent by weight max.

  18. How about a video on how to make NaCN from potassium ferrocyanide including avoiding the brown polymer(rapid mixing)and avoid sodium formate and ammonia from decomposing of NaCN(use 2-3percent extra NaOH).NaCN water solutions degrade at a rate of 0.1percent daily!

  19. There's an experiment where copper powder is made conductive.
    Oversimplified: By attaching an antenna to a jar of copper powder, the current induced in the antenna by lightning strikes in the area welds the powder particles together making the non-conductive mass conductive.
    Perhaps an electric spark of the right amplitude could make the "ink" conductive after the reaction?

  20. Would it be more usefull to use as a soft metal alloy i.e. add tin to improve the conductivity of the metal instead of what id imagine is just stacked layers of large copper sheets kinda like paint.

  21. maybe if the copper formate dry in inert gas (example: argon or nitrogen) the conductivity and strength would be better.

  22. I've wondered whether copper formate could be used for through-hole plating.
    I know there is a way to do it at home which involves thermal decomposition of copper hypophosphite. It would be nice to be able to do the same thing with copper formate.

  23. At the heating stage would keeping the copper formate tetra hydrate under an inert gas improve conductivity by yielding a purer product, ie is oxygen a factor with the poor bonding. Also would the conductivity improve by UV sintering of the final copper product

  24. Rant: consider the dedication and passion chemplayer put into his hobby chemistry videos, only to be shut down by YouTube! Yet, dumb and pointless pseudoscientific videos featuring molten salt/aluminum poured onto oils or candies, or red hot knives cutting through everyday objects (e.g. plastic toys)  with  emission of toxic fumes, are allowed to stay on YouTube. It is utterly outrageous!

  25. Photonic curing/Laser sintering is known to decompose Copper Formate into solid Copper quick enough such that formation of CuO during the process is neglectable.

    https://hackaday.io/project/103142-printed-circuit-boards
    https://www.youtube.com/watch?v=I1NS95dGPdU

    I'd be really interested in recipes for inks. Mixing with (coated) copper nano particles seems to be very common.

  26. Thanks for the information. As electronics engineer, and also a PCB maker, i can say that this isnt suitable for Through hole plating, because holes has to be plated in around 35um – 50um thickness of really conductive metal (such as silver, copper, solder or other materials), but holes has to be "though", because you will stick component leads through them. Also, not reliable, but still, sience is in the 1st place 🙂

  27. You are a scholar and a gentleman and I enjoy your content. I am very much looking forward to the through hole plating experiment!

  28. That's brilliant and helpful! I'm going to try this myself! This might actually fix a problem in my research. I'll credit you if it does. Thx.

  29. Vapour deposition with CO2 laser etching is probably the most controllable solution for at home hobbyists. That is.. if they build the units themselves already for other projects. Really interesting reaction, could this also be used as an additive in photonic cintering inks? A Xenon bulb might produce enough energy to decompose the solution into copper?

  30. In the future multi-function 3d printers will build replicates of itself. Not only the structure but the electrical motor and printed circuits and all from recycled material.

  31. From what I was reading it does not specify that this has a melting point of 200 celcius in or out of water. What I was wondering is if it does not need water would the coating be more uniform and conductive? The boiling water must be contributing to the messy layers. Or maybe some sort of surfactant in the water.

  32. if this stuff sticks to steel at all it could make a good copper plating or similar to parkerizing solution?

  33. Did you ever do the vijaeo on the process of making mini circuit boards what for the angry pixies as you said electrical enginerds use?

  34. Overkill and not so on par with the application you want it to be: i.e: conducting.
    I use a simple Zinc spray on non conductive substrate then after the layer dries i dip in Copper sulfate for a "Single Displacement Reaction" – now the entire substrate is conductive and ready to be electroplated at once. not just areas close to the cathode. Simple & low cost. check out my Metallizing 3D printed plastic models on twitter hashtag #HomeElectroForming

  35. Thank's I'll give this a try (perhaps I will mess around with some solvent to precipitate it out because I'm impatient to wait for weeks to evaporate) maybe you can give it a try and cover the copper (II) hypophosphite since the literature is scarce and from H3PO2 (50% aq.) and the above prepared Cu(OH)2CO3 I get a dark brown precipitate that I expect to be metallic particles due to the reductive properties of the acid (which isn't forbidden here and I have enough of, though salts of it are missing from my collection). All I found was methods to prepare it in solution from Ca++ salt to be used for electronics… I couldn't even find info on the color of the salt which I intend to use as a catalyst additive. Keep up the good work!

  36. Awesome video could you do a show on making a copper strike solution . I've also heard of woods plating liquid. I'm looking for a way to nickle plate aluminium without having to zincate the aluminium first thanks for the info

  37. I have used the carbonate – copper sulphate reaction to try to make cupramonium hydroxide cellulose solvent, but i found that adding carbonate to copper sulphate i would produce different coloured precipitates on different runs. I believe that the product is a mixture of basic copper sulphate (CuOH)2SO4, copper carbonate CuCO3, basic copper carbonate (CuOH)2CO3, and possibly copper hydroxide as well. What mix of products one gets seems to vary quite a bit with small variations in temperature or concentration.
    As an alternative i electrolysed solid copper anodes in carbonate solution to eliminate the possibility of making basic copper sulphate.

  38. maybe if you added some other copper salt to it, the formate can reduce the excess copper and form a more solid ink

  39. I think I synthesised it. I was dissolving Al in CuSO4, decanting Cu particles. They turned dark upon drying = oxide. So I tossed some formic acid 85% in and got substance of beutiful azure color. Much nicer than what I see in video, actually. But that may be due to camera or monitor or both.

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