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Silver Solution Ink Makes Faster Flexible Circuits 36

judgecorp writes "Silver-based compounds dissolved in ammonia could make finer and more flexible circuits, according to researchers at the University of Illinois. Existing inkjet based circuit printing systems use particles which are less predictable. The silver-based ink remains dissolved until the ammonia evaporates, and can be delivered through 100nm nozzles. In all senses, it's a better solution."
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Silver Solution Ink Makes Faster Flexible Circuits

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  • Corrosion? (Score:4, Interesting)

    by Kenja ( 541830 ) on Wednesday January 18, 2012 @09:00PM (#38743784)
    There's a reason copper or gold is used in circuit boards despite silver being a far better conductor, how does this new solution avoid corrosion?
    • This [nace.org] suggests corrosion is not a problem. Highlights: "It is quite resistant to corrosion and does not oxidize easily, although it readily forms a surface tarnish of silver sulfide." and "Silver plating is widely used on contacts and other conductive parts in electrical apparatus such as switchgear and motor control centers because of the superior conductivity and longevity."

      • That's why everybody uses gold contacts. It's more expensive [and people see the word 'gold' and automatically overvalue it compared with most anything else, particularly if it uses the word 'silver'], and is also wears out faster through use, hence also needs to be replaced more often, while providing no noticeable difference in actual performance.

    • It doesn't need to, it should be fine under a layer solder mask/conformal coat/lacquer with plated contacts if necessary.
      In a flexible circuit you'd be sandwiching it between two layer of polymer anyway

    • Copper corrodes far worse than silver does.

    • Re:Corrosion? (Score:4, Insightful)

      by wierd_w ( 1375923 ) on Thursday January 19, 2012 @12:31AM (#38745258)

      Assuming this is metalic silver being deposited (this process seems eerily similar to traditional silver mirroring processes with ammonia, dextrose, and silver nitrate) then it can be rapidly plated with gold using a solution bath. (Gold dissolved in nitric and hydrochloric acid mixture)

      An interesting idea would be to print the two solutions (dextrose + ammonia) + (silver nitrate) with a dual head printer, then print dissolved gold after it has had time to deposit.

      This would chemically replace/plate (depending on thickness) the silver traces with gold ones. A simple distilled water wash afterwards would clean up the piece.

      Makes me wonder if I could repurpose a color print cartridge for this process. I strongly suspect that the nitrate and aqua regia solutions would be very very bad for the printheads though. (Dextrose + ammonia solution would probably just clog and nothing more.)

    • Re: (Score:2, Informative)

      by Anonymous Coward

      There's a reason copper or gold is used in circuit boards despite silver being a far better conductor.

      Silver isn't a better electrical conductor than copper, it's a better thermal conductor.

      Silver is tremendously better at conducting heat than aluminum, and slightly better than copper and gold. In the past, I've melted blobs of silver solder over flat aluminum heatsinks, mostly to absorb temperature spikes (to steady temperatures).

      How does this new solution avoid corrosion?

      It isn't really necessary to avoid the corrosion of silver in most cases (in breathable air). Unlike copper oxide (a semiconductor/insulator), or aluminum oxide (insulator), silve

      • by tmosley ( 996283 )
        Uhh, silver is the best metallic conductor of electricity their is. Get your facts straight.
  • We get a Silver Ink story, as if it hadn't been invented years ago available at any Frys electronics ready to mend any severed circuit.
    • by tobt4josh ( 234448 ) on Wednesday January 18, 2012 @09:07PM (#38743850)

      The fact that this new ink reaches the bulk conductivity of pure silver upon annealing is nothing short of amazing. My company has been working on some printed electronics application, and most of the conductive inks (including silver based) have conductivities that are too low to conduct any useful amount of current.

      • Depends on the scale I guess-- I have a cousin that once used a silver ink pen to repair a garage door opener. Not sure where it was on the circuit but something tells me if the circuit fractured to begin with it must have been one of the 5HP move-y bits
      • There are a few silver nanoparticle inkjet inks on the market with very low resistance. ~0.2 ohm per square for water based and even lower for solvent based inks.

        • There are a few silver nanoparticle inkjet inks on the market with very low resistance. ~0.2 ohm per square for water based and even lower for solvent based inks.

          I wouldn't call 0.2 ohm per square low resistance.
          If I would print a trace of 10 mils width with a length of just one inch (1000 mils) with the ink you mention, it would have a resistance of 20 ohms.
          This system must have far lower resistance to be useful.

  • by Hartree ( 191324 ) on Wednesday January 18, 2012 @09:08PM (#38743856)

    http://colloids.matse.illinois.edu/ [illinois.edu]

    Jennifer Lewis' research group here at the University of Illinois did this work.

    They've got a link on that page to a youtube video that shows how to make and use this conducting ink, but it goes through Boing Boing and is down at the moment due to the SOPA protest.

    Here's a direct link: http://www.youtube.com/watch?v=dfNByi-rrO4 [youtube.com]

    Seriously cool work.

  • > In all senses, it's a better solution
    Ammonia? Not in my sense of smell.

    Tell me when they have a silver/Mendocino Oatmeal Stout solution.

  • Maybe this will work in a open area building stuff in a line but trying to fit that in to a area with other stuff in the way? Maybe to build / puttogether parts of the crane on site.

    What hills and and places with uneven ground?

  • I want to see this tech used in cables, particularly headphone and low-voltage power cables.

    This is assuming it would fare better than braided copper.

    • I have a feeling unless the printing was done braided, the skin effect would still be an issue in the analog world. On the other hand, you might be able to get Litz windings incredibly cheap compared to the current methods. Too bad the marketing folks will hear Litz and increase the cost 10x anyways.
  • Now we just need an order form for this, and a good how to, on filling up a used printer cartridge with this ink.

    I've always wanted to build a small CNC machine to make custom PCB circuit boards, but with this, I might not have to.
  • I myself recommend a seven percent solution for the best effect.

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