Silver Mylar in computer keyboards (question)

Discussion in 'General Electronics Chat' started by Rolland B. Heiss, Apr 12, 2015.

  1. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    I suppose I can find the answer to this question by experimenting when I can manage the time but I was wondering about this silver Mylar stuff inside of keyboards. I'm thinking the silver must be sprayed on the outside of the Mylar layers which would make it useful for a circuit board using scissors to cut out and paste the connections in any layout or configuration I might wish or dream up. Do any of you know if the silver is indeed on the outside of the Mylar or is it contained inside the sheets? Given that the best price for merely selling the sheets I've found so far is 10 cents a sheet (which is pretty good really) the thought occurred to me that projects using copper or other wire might ultimately be more expensive than reusing the thin sliver in the Mylar and I believe (correct me if I am wrong) that silver is a better and more reliable conductor than copper is. Besides, the project would weigh less and not be as cumbersome as one with wires all over the place wouldn't it? Has anyone here used this silver Mylar in projects of your own? I'm very curious!
     
  2. Roderick Young

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    Feb 22, 2015
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    I could be wrong, but I don't remember noticing silvery stuff in membrane keyboards I think it might be some kind of conductive polymer, and not a very good conductor at that. The shiny mylar used for helium balloons and gift wrap I believe has aluminum deposited on it. I'll delete this post if someone knows for sure.
     
  3. GopherT

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    Nov 23, 2012
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    It is aluminum on the Mylar balloon. The polyester (Mylar) is not very stable at high temperatures and aluminum is beyond difficult to solder.
     
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  4. Rolland B. Heiss

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  5. Rolland B. Heiss

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    I appreciate your input and have posted a video below (apparently the video is just above my response actually) which is where I first learned about the possibility of silver being in the Mylar. Since then I've found a whole host of other places on the web that seem to indicate that there is indeed silver in most of them and people pay up to 10 cents a sheet or less for them. However, I do not know how to test for silver myself at the moment but there must be something to this since people have been buying them for years in order to extract the content from what I have garnished.
     
    Last edited: Apr 12, 2015
  6. WBahn

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    Mar 31, 2012
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    Let's look at the numbers he bandied about, namely that it takes about 24 keyboards to recover 1g of silver. There's a bit over 31g in a troy ounce, so that means that you would need to process about 750 keyboards to get 1 troy ounce of silver, which is presently selling for about $16.50. And that's assuming that your time is worth nothing AND that it doesn't cost you anything to process the mylar films. Since we are talking about 2.2 cents of silver per keyboard, that doesn't leave you will much room for the nitric acid involved (or anything else). Also, if your time is only worth minimum wage, you can only spend about 10 seconds per keyboard and you have used up the entire value of the silver.
     
  7. Rolland B. Heiss

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    Feb 4, 2015
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    That wasn't the point of my initial post WBahn. My question was in relation to how to use this silver to make lighter contacts using scissors in electronic projects. I'm not trying to get rich but rather, looking to use things I can get free for my projects that may be more efficient in smaller compartments without all of the wires.
     
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  8. WBahn

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    The silver (and it's not always silver) is deposited onto the mylar, not simply sprayed on. So it isn't just a simple matter of buying mylar sheets and then applying your own silver in the pattern you want. If you were going that route, you would most likely buy silverized mylar sheets and then apply an etch resist pattern and dissolve the silver that you didn't want on there.

    It is already a pretty easy and common practice to etch switch contacts onto a PCB and then use a mechanical means to apply a shorting bridge in order to close the switch. One simple, cheap -- and rather unreliable -- way is to use a sheet protector with holes cut in it as a spacer and then a sheet of aluminum foil on top of that. Something like that would commonly be done on a proof-of-concept implementation.
     
  9. Rolland B. Heiss

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    Feb 4, 2015
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    I wasn't thinking about buying the Mylar but rather removing a few keyboards from county land which have been dumped illegally in order to use them for projects and also help clean up my community. So, if they are deposited onto the Mylar they can be used just like using a pencil and drawing leads on a piece of paper with graphite and placing a battery on top of them in order to light a simple LED for example. Yet graphite isn't nearly as good as silver or other conductors is it? As I type this there are at least three or four keyboards that people used to type lord knows what on when they were still in use. I'm thinking about recycling them for a good and useful purpose but it seems to me you are trying to dissuade me and for what reason, well... I don't know. I'm not wanting to apply my own silver to sheets but rather utilize the silver already contained on said sheets. Look, what I'm proposing is to cut silver strips from the Mylar and string them together in order to form circuit boards and if I can do such a thing on an envelope or some other piece of paper with a mere pencil then I can have even better results using this recycled waste as opposed to using wire. Perhaps I have been remiss and didn't make my intentions clear enough to understand. I did have a long day at work and am very tired but I appreciate your input. The misunderstanding is most likely my fault I suppose.
     
  10. WBahn

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    Mar 31, 2012
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    By all means, give it a go. Whether you are successful or not depends on how much time you are willing to devote to it and what constitutes "success" for your project.

    You might think about just how you plan to connect these bits and pieces of mylar together so as to string them together into a circuit.
     
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  11. jpanhalt

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    Jan 18, 2008
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    There has been a bit of interest in using a modified Tollens reagent to print electronic quality and quantity of silver on all matter of substrates. Here is the original description: http://pubs.acs.org/doi/abs/10.1021/ja209267c

    Prof. Lewis is the lead author. If you search on her you will find additional links, including to a startup that is using the ink to print inside devices made with 3D printers. I wrote a somewhat more extended abstract of the article (attached).

    John
     
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  12. takao21203

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    Apr 28, 2012
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    you can hang them in your water tank for controlling micro organisms
     
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  13. jpanhalt

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    Why not just use silver? Much cheaper per ounce.

    John
     
  14. shortbus

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    The silver/aluminum is applied by vacuum metalizing, usually over a synthetic varnish. Worked years ago at a plastics plant that made car parts. All of the "chrome" bezels and other chrome plastic interior parts are vacuum metalized. After spraying the parts they are clipped on to 'spiders' on racks. Then put in a large vacuum tank with aluminum sheet ribbons and heated with vacuum drawn on the tank, when at the correct temp and pressure a big capacitor bank is discharged through the aluminum ribbons and vaporized. The aluminum sticks to the varnish. I'm sure that the 'silver' mylar goes through the same type of process.
     
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  15. Alec_t

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    If you have some of the metallised film handy, try soldering to it with ordinary leaded solder. Silver should solder easily; aluminium won't.
     
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  16. alfacliff

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    Dec 13, 2013
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    there is also paintable silver for repairing pc boards, conductive as well. there is also spray and paintable copper and nickel too.
     
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  17. PackratKing

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    Jul 13, 2008
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    Actual silvered mylar, would be as rare as snake-feet... if it existed at all... the majority of shiny metallized mylar, is either done by vapor deposition in a vacuum, or chemical precipitation.
    I have used the Rochelle salts / Silver Nitrate method of depositing silver on mirrors...and other accessories associated with camera repair, and telescope mirrors... It is certainly not cheap to do, and requires some fairly nasty chemicals...
    Nitric acid, and Aqua Ammonia just to name two... either of which require respirators etc. to work with...
     
  18. jpanhalt

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    I have no idea what you mean. Silver deposited by vapor or by chemical means is silver. I am certain I can deposit a shiny layer of real silver on polyester film (Mylar) using the original Tollens reagent. We did it many times on glass using simple glucose as the reducing agent (http://en.wikipedia.org/wiki/Tollens'_reagent). The surface scratches easily, but is hard to get off completely without using nitric acid or something similar. You also overstate the risks with using those reagents at the concentrations needed for silvering.

    That is not to say that the shiny Mylar balloons and such are silver plated. I suspect they are probably aluminum as has been stated.

    John
     
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  19. Hypatia's Protege

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    Mar 1, 2015
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    IMO the most significant hazard associated with common 'mirroring' processes owes to the potential for fulminate [CIP. AgCNO] (and, to a lesser extent, azide) formation -- In addition to the familiar toxicity associated with most compounds liberatory of the "CN-" ion, fulminates are treacherously explosive! Although the likelihood of inadvertent fulminate/azide formation is modest, It can and does happen! Hence, in view of the 'stakes', caution is advisable...

    To prevent fulmanate formation please refrain from use of organic solvents...

    Best regards and be safe! :)
    HP
     
    Last edited: Apr 14, 2015
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  20. PackratKing

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    Jul 13, 2008
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    + Hypatia's Protege, Oh yes... Silver Fulminate... I had a chemist friend, that demonstrated the explosive power of that marvelous concoction...
     
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