back to article Oxidation-proof copper could replace gold, meaning cheaper chips, says prof

Scientists claim to have found a way to stop copper from oxidizing. If they're right, this could potentially allow copper to replace gold in electronics, leading to lower costs and, ultimately, cheaper components. The academics at Pusan National University in South Korea say they have developed a method to fabricate atomically …

  1. Paul Crawford Silver badge

    If it is the atomic-level smoothness that stops oxidation, how will it fare at joints or other sites with any damage to that aspect?

    1. the spectacularly refined chap Silver badge

      That was my thought too. Instead of "damage" though, simply think "wear". Contact surfaces rub against each other on regular insertion and removal. Small amounts of wear are not generally an issue and indeed may even be desirable since they give the connection self-cleaning properties.

      However here we are talking about surfaces smooth right down to the atomic scale. Surely a single insertion is going to scuff the surface sufficiently to completely destroy that fancy finish you're just applied?

      1. Toni the terrible

        Adhesion

        An atomically smooth clean surface applied to a similar surface is going to stick, excedingly well, hope you dont want such surfaces to be seperated. And if you do seperate then they will unlikely be smooth anymore - so corrsion restarts?

        As a permanent joining method its fine

  2. iowe_iowe

    Some hope for humanity?

    It's innovation like this that helps you believe that we might - just might - wake up and fix the mess we made...

    1. Filippo Silver badge

      Re: Some hope for humanity?

      We can only hope, but all of the really big problems we have have been ultimately caused by failures of politics, culture and/or economics. Technical solutions can only give breathing room.

    2. cray74

      Re: Some hope for humanity?

      we might - just might - wake up and fix the mess we made...

      Cheer up! The ozone layer is on a path to recovery, acid rain has dropped across North America and Europe, forests are recovering in North America and Europe (North America is more forested than it has been in decades), waterways are recovering, China's air pollution is dropping, global extreme poverty is down, global literacy rates are up, whale populations are bouncing back, and, until late February of 2022, deaths due to war were at historical lows.

      There are challenges ahead, but we've dealt with a lot of other long-term challenges in the last 50 years.

      1. Blank Reg Silver badge

        Re: Some hope for humanity?

        Right now one well targeted death could bring the deaths due to war number down

  3. Martin an gof Silver badge
    1. Mike 137 Silver badge

      Re: The Royal Mint didn't see that coming

      "Royal Mint wants to turn your old phone into gold"

      But apparently only to turn the gold into useless bling - "gold, which they’re planning to use to make commemorative coins"

      Actually, we have (world wide) such masses of gold that if it were all released on the market its value would collapse. The same is true for diamonds - the moment you buy one it's worth about half what you spent, as it's a purely artificial scarcity. Not really anyone's best friend.

  4. Richard Tobin

    Effect on copper prices

    Demand for copper is 25.5 million tonnes per year, and 66.4 tonnes of gold was used in electronic components. So using copper instead of gold would increase demand by a couple of millionths. That's not going to have any effect on prices.

    1. teknopaul Silver badge

      Re: Effect on copper prices

      Came here to say the same, interesting tech but conclusións are absolute nonsense.

      Gold is used currently, but not such a thin layer, so if this tech were brought to market, the copper volume used for it would be far less than even current gold usage.

      Perhaps that this tech will actually turn out not to prevent oxidisation completely and some cheap tat will get a shorter life? And I'm sure Apple with jump on any tech that shortens the life of its phones.

      How much gold gets successfully recyled from circuit boards by recyclers playing with nasty chemicals in the third world. Maybe this could help prevent that?

      I am sure other conclusions could be drawn that are at least plausible.

      1. John Robson Silver badge
        WTF?

        Re: Effect on copper prices

        "And I'm sure Apple with jump on any tech that shortens the life of its phones."

        Really? You pick on the one company that has had exceptionally good long term support for it's handsets. The last seven generations of their phones (not counting the SE models, since they're just a repackaging of one of other generations) all support the latest version of iOS.

        1. DS999 Silver badge

          Re: Effect on copper prices

          And the two generations before them were supported with security updates until last fall.

        2. Loyal Commenter Silver badge

          Re: Effect on copper prices

          Yes yes yes, software support is all well and good, but when it has a soldered and glued in battery that, with a regular charge / discharge cycle will begin to degrade after about 18 months, that doesn't count for very much.

          Yes, I know battery technology has improved over recent years, but gains are incremental, and the same applies to pretty much all lithium ion or lithium polymer batteries (I'm not singling Apple out here, except on the poor repairability).

          My old phone eventually had to be replaced due to the battery losing its ability to retain charge beyond a few minutes. The up-side here is that I didn't pay £1,000 for it, so paying for a third part to attempt to unseal it, replace the battery, and not break any part of it (or sending it to the manufacturer for a replacement for $wedge) was less economically viable than buying a new phone, which also didn't cost anywhere near as much as an iPhone (IIRC, about £190, and with capabilities equivalent to a "flagship" phone from approximately two years earlier).

          Anyway, I've wandered from my point a little - Apple's software support might be "second to none", but their hardware support for older devices is more like "none". A colleague of mine once had to have an argument with one of their "geniuses" over a frayed charging cable, which they adamantly claimed was "water damaged" so wouldn't replace free of charge, and demanded £40 or so for a new one. When you fleece your customers in that way, you can afford to support software on devices that are approaching their economic end of life.

          1. DS999 Silver badge

            Re: Effect on copper prices

            The battery is neither soldered nor glued in, and is much easier to replace than in many Android phones such as Samsung's. But please, continue with the Apple hatred from a position of ignorance.

      2. Michael Strorm

        Re: Effect on copper prices

        The conclusion notes that the price of copper is rising and that this use may further increase prices (*) undermining the economic case.

        Except that, as the article already noted, "copper comes in at around $10k per metric tonne, while gold is over $62m per metric tonne"

        So currently copper is just 1 / 60,000 the price of gold. Even if that went up ten times(!), the cost would still be a negligible percentage of the price of the gold currently used- i.e. close to nothing in comparison- and shouldn't affect the economics significantly.

        (*) Only, as others have already pointed out, it probably won't.

        1. Blank Reg Silver badge

          Re: Effect on copper prices

          sure it would still be tiny versus the price of gold, but a 10x increase in the price of copper would have a huge impacts on the cost of electronics, electric motors, generators etc.

          1. Michael Strorm

            Re: Effect on copper prices

            No doubt about that, but it was the economics of this specific case I had in mind. As far as that's concerned, barring all but the most ludicrous increases in the price of copper (i.e. several orders of magnitude) this technique would- assuming it works and everything else remaining equal- still be economically worthwhile regardless.

          2. Loyal Commenter Silver badge

            Re: Effect on copper prices

            This is true, but an annual increase in demand of 66.4 tonnes (well, actually more like ~22 tonnes, because the atomic mass of copper is roughly a third that of gold) is about the amount you'd need to do the plumbing in a new housing estate of 100 homes. In other words, so close to negligible on the global scale (currently about 28 million tonnes annually) that it could safely be considered to be zero (an increase in demand of less than 0.00001%).

            1. Philip Stott

              Re: Effect on copper prices

              Tongue firmly in cheek here, but wouldn't using the relative densities of copper (8.9) and gold (19.3) be more appropriate than atomic mass?

              1. Loyal Commenter Silver badge

                Re: Effect on copper prices

                That would depend on whether you are talking about the thickness of the coatings in atoms, or in nanometres. As someone with a (distant) background in chemistry, I tend to think in terms of the former, but from an engineering standpoint, one may well be thinking in terms of the latter. Either way, the point is that you wouldn't be replacing one tonne of gold with one tonne of copper, you would, at most, be replacing it with ~460 kg (using the relative densities) or ~323 kg (using the relative atomic mass).

                Of course, the whole point is moot, if the cost of depositing the coating, atom by atom, is prohibitive. Bear in mind, that a layer only 1 micrometre thick is around 4500 layers of atoms.

    2. ian 22
      Unhappy

      Re: Effect on copper prices

      While not a long-term solution, we can replace copper cables with fiber optics, and recycle the copper. After that, we can begin to use silver as a replacement. That, or carbon fiber.

  5. Anonymous Coward
    Anonymous Coward

    Why is oxidization a problem?

    Why not replace the bonding wires in IC packages with ordinary cheap copper and fill the whole package with inert gas? (Apart from the Invasion of the Ukraine causing a neon shortage.)

    1. A Non e-mouse Silver badge

      Re: Why is oxidization a problem?

      Why even add the gas? Surely oxidation is only a problem when you're making the connection?

    2. El Bard

      Re: Why is oxidization a problem?

      Copper is already in use for the wire-bonding of chips

      https://news.skhynix.com/wire-bonding-a-way-to-stitch-chips-to-pcbs/

      Oxidation, in this case, is a problem because it shortens shelf-life of copper wires (just a few microns thick)

      1. Christopher Reeve's Horse

        Re: Why is oxidization a problem?

        Well perhaps in the future oxidation won't be such a problem - once we've destroyed the natural environment sufficiently for oxygen levels to plummet that is. Nature always finds a way.

    3. Peter2 Silver badge

      Re: Why is oxidization a problem?

      You don't need to use Neon. If you want a box filled with a cheap readily available gas which is heavier than oxygen then CO2 would do the job. (it only rises when heated in an engine and then thrown out of the exhaust pipe)

    4. Toni the terrible

      Re: Why is oxidization a problem?

      Why not use dry nitogen - its quite common...

  6. trevorde Silver badge

    Better use for oxidation-proof copper

    Speaker wires

    https://www.amazon.com/AudioQuest-Terminated-Speaker-Cable-Discontinued/dp/B000J36XR2/ref=cm_cr_pr_product_top

    1. Doctor Syntax Silver badge

      Re: Better use for oxidation-proof copper

      Look forward to an order of magnitude increase in price.

  7. El Bard

    Not so fast Jeong-san

    First of all, this is nice. The surface science guy in me very much appreaciates the article. However...

    "Oxidation-resistant Cu (copper) could potentially replace gold in semiconductor devices[...]"

    What does this refer to? To gold plated copper pads (in surface finish with ENIG/ENEPIG)? I hope not... because the copper pads are many (10+) microns thick, and getting to that thickness with sputtering (the technique used in the work) will take forever.

    Wire-bonding? Copper is already in use, so the application would then be related to augmenting the shelf-life of copper wires. Would this mean using the single-crystal copper wire mentioned in the article? Because what with wire-bonding being mostly used for lower-end applications, I am not sure any increase in material costs is justifiable.

    Moreover, as is mentioned in the article "The flatness of a surface is decisively influenced by the interface structure between the film and the substrate"

    The substrate is a double-side polished aluminum oxide. So how are you going to get THAT into the picture when it comes to making the process practical for electronics?

    I can sympathize with the need to make bombastic claims in today's engineering ruled world, but they might have chosen the wrong application.

    1. Loyal Commenter Silver badge

      Re: Not so fast Jeong-san

      What does this refer to? To gold plated copper pads (in surface finish with ENIG/ENEPIG)? I hope not... because the copper pads are many (10+) microns thick, and getting to that thickness with sputtering (the technique used in the work) will take forever.

      I wonder if the technique could be applied to the surface of pads made with conventional techniques, or whether the sputtering (as far as I know, similar to thin film vapour deposition techniques) would just preserve the surface features, but a couple of atoms higher? I guess it depends on whether this can be applied to a non-smooth surface to smooth it by "filling in the cracks".

  8. katrinab Silver badge
    Meh

    Will this be any use in practice

    Let’s take for example the RAM sticks I’m due to take delivery of later today.

    The contacts on the side of the board that I shove into the motherboard will most likely be made of gold.

    When I shove it into the motherboard, it will get a bit scratched, which is intended behaviour by design to give it a better connection. What would happen if single crystal super-smooth copper gets scratched, would it still have anti-oxidation properties.

    Also, out of the £380 I paid per stick, I suspect very little of it is for the purchase of the gold in those contacts. This copper thing sounds like it would be much more difficult to apply, so would there actually be any cost saving?

    1. Mike 137 Silver badge

      Re: Will this be any use in practice

      "most likely be made of gold"

      Actually they're most likely to be coated with gold (often over nickel) to a median thickness of about 15 microns (range around 3-50 microns depending on the application).

      When a connection is mated, the gold will be scratched to some extent. Depending on the connector type, the gold may either only be partially scratched through, resulting corrosion resisting endurance for multiple insertions, or fully scratched through (for thinner coatings) at high insertion force, resulting a gas tight contact with the underlying metal. In this case, the remaining gold prevents corrosion attacking the edges of the gas tight contact, but the downside is that insertion endurance can be low or once-only.

      1. TRT Silver badge

        Re: Will this be any use in practice

        Presumably the monoatomic copper layer will also be a surface treatment.

      2. Peter2 Silver badge

        Re: Will this be any use in practice

        I do electroplating and gold is a common thing to plate for the obvious shiny factor. (Even at a hobby scale it works out as perhaps £0.50 per square inch to do to a reasonable thickness; it's not exactly expensive!)

        When plating a thin layer of gold would be between 0.10 and 0.25 microns. A normalish amount to plate would be 0.5 to 1 micron, depending on application. Jewellery such as rings gets a thicker 3 to 5 micron finish to allow for wear with pulling it on and off and rubbing it against things. The electoplating process limit is around 5 microns depending on the composition of the chemicals that your using. I don't think anybody can put 50 microns down with modern methods.

        Historically you could have done it; Mercury fire gilding could probably have done it for instance. Mercury is a liquid at room temp, and it dissolves gold. You therefore mixed mercury with gold to form a form of liquid gold, paint it on, and then heat the item to >400c. The mercury then boils off, and you have a really, really thick layer of gold deposited. However, Mercury fumes are not that great for your health, and as a result the Health & Safety people have more to say about people using that process this they do with the modern "safe" version which dissolves gold using potassium cyanide.

        And with that little bit of chemistry that most people won't care too much about over, something more interesting is that copper basically "eats" gold atoms. Nobody plates copper over gold. (more than once)

        Also, electroplating suffers from similar problems as with painting in that the preparation amounts to 80% of the work, with only 20% going to slapping the top layer of paint on. The same applies to electroplating gold; the layer your putting on is so thin that it shows through the layer underneath, so everybody puts down a thick layer of nickel which is nice and shiny first. You then put the (thin) gold on top of the nickel so you get the gold colour from the gold combined with the shinyness of the nickel.

        If I was plating RAM chips which are probably going to be moved between systems perhaps twice in their lifetime then i'd probably only have a .10 micron thickness of gold over the top of about 20 microns worth of nickel. The gold layer will get scratched in places on an atomic scale, but the nickel layer will prevent any oxygen from penetrating to the copper.

        1. Man inna barrel Bronze badge

          Re: Will this be any use in practice

          Mercury fire gilding, of the traditional form, is extremely hazardous. I think this is the basis or ormolu gold plating, that could be applied to non-metallic items. You make an amalgam of gold in mercury, and paint that on the object, The object is then baked, which evaporates the mercury, leaving the gold behind on the surface. I think some burnishing is needed after that.

          The big problem is mercury vapour. Workers in this trade were lucky if they lived into their forties.

          Mercury-gold amalgam is also used in gold mining, to extract very fine gold particles. The amalgam clumps together, making it easier to extract the gold physically. This can cause massive pollution problems.

    2. Chipwidget

      Re: Will this be any use in practice

      I just read that there is about 0.1g of gold in a CPU chip and I expect they have more than most. So at $62 million per tonne, that works out to about $6.20. If the copper was absolutely zero cost, your stick would come down to about 377 pounds. Might make more difference on cheaper things but they probably have less gold in them too

  9. Andy The Hat Silver badge

    I love that quote ...

    "...about 66.4 tonnes of gold was used in electronic components last year – which is likely to be much lower than the figure for copper."

    Given the average thickness of gold, the areas using gold and comparing that to the average area of a PCB, perhaps 70% covered in copper, have multiple copper layers and many wire/film interconnects, that has to be the biggest understatement of the century.

  10. myhandler

    "atomic sputtering epitaxy"

    Is that the same 'sputter' as the one in the Eels' song Novocaine for the soul?

  11. John Brown (no body) Silver badge

    semi-permanent resistance to oxidation

    "semi-permanent resistance to oxidation"

    Isn't "permanent" one of those absolute words? How can something be semi-permanent? Or is it something almost exactly the same but different?

    Now, apart from all the excellent chemical and materials explanations given above, for which I thank the contributors for expanding education, does this not strike people as being similar to the lead-free solder whiskers issue? ie, look for "cheaper" or "safer" and end up with "shorter lived" because the corrosion resistance os only "semi-permanent", ie not permanent so has a shorter finite life than using gold?

  12. Dave 126 Silver badge

    Copper look around:

    After Papua New Guinea became independent from Australia in 1975,[5] Bougainville was given provincial status in 1976.[6]

    In 1988, tension erupted into a civil war between the Bougainville Revolutionary Army and Papua New Guinea government forces.[5] One key issue of conflict was the Panguna mine, which was closed in 1989.[6] The civil war ended with a ceasefire in 1998, that was followed with the Bougainville Peace Agreement from 2001.[7] The agreement established the Autonomous Bougainville Government,[8] and mandated a referendum on the independence of Bougainville to be held 10-15 years later than the election of the first Autonomous Bougainville Government, which was June 2020 at the latest.[5] The referendum would be non-binding, and the final say would rest with the Papua New Guinean government.[5][9]

    In November 2019, Raymond Masono, Vice-President of the Autonomous Region of Bougainville, campaigned that he would plan to reopen the Panguna mine if the referendum resulted in a vote for independence. Panguna closed in 1989 due to the civil war and is now estimated to hold copper worth up to $60 billion. With independence, all of Papua New Guinea's interests in the mine would transfer to Bougainville, giving it a 60% share in all projects and retaining all mining licences. The remaining 40% would be left for investors to bid on.[10]

  13. PRR
    Boffin

    > "Copper comes in at around $10k per metric tonne, while gold is over $62m per metric tonne"

    No electrical engineers in the house??

    For carrying electricity you DON'T go by weight. You want Mho per dollar. (Mho is the inverse of Ohm, so Conductivity.)

    Aluminums are best. Gold is terrible (but has no Oxide).

    Weight is a minor factor in overhead spans, and there is a zig-zag zone where hi-test Aluminum and Al-clad Steel compete with plain steel. (Yes, steel is excellent for the price and for the strength, but must be awkwardly large for its conductivity and good Oxide (rust) resistant joints are difficult.)

    1. StargateSg7

      I remember the OLD DAYS (1980's/1990's) when ALUMINUM (or Aluminium fer ya Brits!) was used for ALL chip interconnects and traces. My suggestion to reduce COST is forget about copper and use U-shaped Micro-Channels for ALL interconnects using a very thin layer of aluminum on the surface of that U-channel using thin film sputtering or vapourization.

      If your surface layers is a U-shaped microchannel, it will perform as a surface conductor using the "Skin Effect" for conductance. It actually outperforms SILVER which is the most conductive metal. Aluminum does oxidize BUT some simple thin film silica (i.e. pure glass) works wonders as a protective layer on top of the Aluminum thin film. The skin effect STILL works even with the thin film of glass on top of the aluminum U-channel surfaces!

      Aluminum is $1.6647 per pound while Copper is $4.7640 per pound as of March 23, 2022 so the price difference is significant!

      ANOTHER OPTION is Intrinsically stretchable and highly conductive polymers (ISHCP) using doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) which has 95% of the conductivity of pure Copper at 1/20th the price! Plus, these polymers can be used to make ALL-PLASTIC CHIPS that are flexible and very, very inexpensive!

      See this link:

      https://www.science.org/doi/10.1126/sciadv.1602076

      The gold nanowires used to connect chips to outside connectors can be CHANGED OVER with the aluminum U-shaped microchannels that act as surface effect conductors. Now chip prices can drop even further.

      And if you REALLY want to be bold, even the chip-traces can be converted to U-channels surface filmed with aluminum and silica to remove the need for all those dopants. A P-N junction could be made out of U-channel within a U-channel USING A CHEAP POLYMER as the semiconductor!

      I have to think further but I think an ALL surface-effect P-N junction diode COULD be made out of aluminum, pure silica (glass) and a polymer to form gates/transistors/etc. for modern CPU, GPU and DSP chip making needs at 1/20th the price of today's processes.

      I will get back to y'all on this!

      Everything in this post IS NOW FREE AND OPEN SOURCE under GPL-3 licence terms!

      V

    2. Loyal Commenter Silver badge

      I don't think anyone is talking about making gold pylons. The considerations for electrical engineering (especially HV large scale stuff) are very different to electronic engineering, which in turn are different to the nanoscale engineering in chips.

      1. StargateSg7

        With modern DIRECT electron beam etching using multiple beam heads (hundreds+!), you can definitely create 100 nanometres and less U-shaped non-channels with sputtered or vapour deposited thin aluminum films to create surface-effect connections and traces. You can still use UV photolithography processes but for accuracy I would probably go with multi-beam electron beam etching of nanoscale U-channels!

        For prevention of oxidation, using plain pure silica or borosilicate glass can ALSO be thin-filmed on the surface of an aluminum U-channel to STILL allow surface effect electrical current transmission. P-N junctions and Diodes which can turned into the gates/logic circuits of a microprocessor and memory storage system can ALSO be crated out of nanoscale U-channels for costs that are 25% and less of current processor manufacturing costs. Polymer-based U-channels can bring that down even further to 10% of today's manufacturing costs!

        Surface effect current transmission using thin film Aluminum U-channels is ONE future of future CPU, GPU, DSP and ASIC production! I think it's a good one to explore for mass market chip micro production!

        V

        1. Peter Gathercole Silver badge

          Love your off-the-wall posts

          This was a while back now, I know, but I've been trawling your posts, and this one had to have a reply.

          If you use very thin film aluminium interconnects, you will have to keep it totally oxygen free for the entire lifetime of the device, because although metallic aluminium conducts well, aluminium oxide is a good insulator.

          If you use a thin film in the presence of oxygen, it could not be thinner than the depth of penetration of oxygen into the surface, otherwise the trace would become totally non-conductive!

          Are you another instance of the amanfrommars AI, or AI simulation?

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