Plasma Metal Coating... In a Jam Jar

in my last video we built this incredible looking thing called a DC sputtering magnetron it uses that cloud of hot plasma to spray whatever metal or inorganic material you want at a sample coating it in that material unlike electroplating where you can only cover conductive materials this device lets you coat anything you want last time we only use plain glass but this time we're going to go through a bunch of other materials as well as how to make these intricate designs on the things that you're coating also this time we're going to talk more about what sorts of materials work well for this process and we'll use a variety of metals from copper to silver to gold we'll save inorganic materials like I tio ybco and alloys for a future video as you've probably gathered by now it's an incredibly capable machine and so it's used extensively in industry it's one of several machines which were required to build every chip in every piece of technology that you use on a daily basis it's also used to make the conductive glass that makes your smartphone possible it's basically it's close to modern magic because you're gonna get so today we're gonna try and really put it through its paces I've been having a ton of fun making all sorts of things from custom shades to prototype electrode arrays and a variety of intricate patterned metal designs but just to show you how versatile this machine is I also covered these snail shells and a dried Hornet in metal before a sample is put into a scanning electron microscope this machine is used to coated in metal so that charge doesn't build up on the sample so it's often used to coat delicate biological materials which are about as delicate as things get even though the plasma itself can get very hot it's fairly straightforward to keep samples cool during the process so that this isn't an issue as such it really can coat just about any solid material be it plastic metal glass or otherwise if you haven't seen it yet I would highly recommend giving the last video a watch if you want to learn exactly how the system works since the last video I've spent my time going through all the suggestions that many of you left and using them to upgrade the machine the version we used last time was never more than a prototype to prove the concept it was just too small which made its use much more restricted as it can only fit about half a microscope slide in at a time so a lot of the upgrades are based around improving the control of the plasma and where the metal is sprayed while increasing the chamber size to accommodate bigger pieces eventually I want to add a shudder as well as a way to rotate the pieces as they're coded so it's more even before we go further I want to first say that you should absolutely go check out Ben's series on sputtering and metal evaporation over on Applied Science as usual the answer to how do I do a really hard technical thing can be found on his channel I put a note at the end of the last video but I really want to emphasize how helpful those videos were for building this so thanks Ben and now having built my system I'm a hundred percent aware of why he chose the parts that he did and the compromises I had to make both to keep the price of my system down and to keep it modular so I could put it away easily eventually I'll be working more towards a system that is much closer to his build as I want to push it to do more and more difficult materials like ybco or daimond so if you want to see how a professional does it go check out those videos like in the description so what have I changed since last time first was to use a much larger jar going from 350 milliliter volume to 750 milliliters this extra volume does mean it's a little bit harder for the pump to keep things at the right pressure but that's manageable in a future video we're going to look at some little additions that will help manage this further and make it easy to stay at pressure also for making the hole for the feed through through the top I switch to a diamond hole cutting bit which works wonders next up I changed how I had my electrodes last time the anode was the thing we were resting our samples on and this led to some weird issues first the mild steel would get hot and start to evaporate a bit which left a weird green haze on the glass second it wasn't really as close to the base plate as it should be and third it wasn't stainless steel which is a much better material for this as it doesn't have the same volatility issues so now the anode is made from a stainless steel cookie cutter I picked up and it's hung off the feed through using stainless steel wire the best part of this is I can now make a little stand to put my sample on and then just lower the chamber over it rather than having to jam my hand up into the tiny jar to get the microscope slide in place the glass tube was made out of a beer bottle which was cut to size and then eventually I used my new glass drilling hole saw to make some holes in it the holes allow any electrons that originate in the center of the plate to flow to the anode without having to travel all the way up the tube when they had to go up the tube it would get filled with plasma which was overheating my samples and screwing with how the metal vapor was moving around beyond that I tidied up the plumbing and added a proper vacuum gauge this is both extremely helpful for monitoring the process but also very interesting as I'm observing effects that I was only just starting to read about like ion pumping and so called get her material effects but we'll talk more about that in a moment I also replaced all of the silicon gaskets with ones made out of Viton rubber which is a fluorinated rubber and much more impermeable to gas last time we used copper for everything because copper is cheap and readily available but it also makes a mess and is the most reactive of the metals we'll use today this makes it easy to get oxides and interesting rainbowy effects but sometimes you just want a nice clean metal so I picked up a tiny sterling silver bread plate for cheap online sterling is 92% silver and does have some other metals in it usually a little bit of copper so it's not a hundred percent pure but it's close enough and works well I also picked up a tiny piece of gold which my wallet is still sore from with a few exceptions most metals work with minimal effort and thus far I've successfully used the noble metals and nickel and they all work well but keep in mind that ferrous metals like iron or steel need to be thinner as they dampen the magnetic field that makes this work I'm sure many of you are wondering about things like titanium and aluminum and I figured out why they weren't working it comes down to two things the first is what's called the sputtering yield rate and the second is the oxides that form on their surface the sputtering yield rate is basically a rough approximation of how quickly different materials will sputter over the same process conditions this site has a great chart which really helps make this clear and I've link to it in the description you can see that copper has a pretty high yield rate which is why even under the relatively high pressure in my chamber it's still sputtered easily now if we look at aluminum already at a baseline its yield rate is lower but whatever that's not so bad just means it takes a little bit more time but now look at aluminum oxide the yield rate is tiny so as we're trying to sputter before any metal will fly that thin layer of oxide has to be sputtered away but you're also fighting any contamination in the chamber as any oxygen will poison the target by rebuilding the oxide layer as its removed to deal with this you need to be able to flow argon slowly into the chamber to flush out any contaminants as they're formed I don't have a fine enough needle valve for that yet and I don't think my pump could really keep up on its own so for things like titanium or aluminum that have this oxide issue I'm going to use a thermal sputtering method in a future video instead in the last we just made plain mirrors but now that the system is working I wanted to work on patterning the material at first just to see if it was possible I tried to use some sharpie to mask off areas that I wanted to not be covered in metal I figured I could just wash off the sharpie afterwards with acetone to reveal the design it didn't really work though and left a release scraggly gross edge and sort of a mess everywhere but it did show that I could pattern things with the machine so I moved on to using a vinyl mask and vinyl cutter which is another trick I learned from Ben the vinyl cutter is easily my new favorite tool in the shop as it's the only thing that just worked the first time I used it and was done in about 30 seconds I'm just using standard cheap vinyl and made a variety of masks both positive and negative and it works remarkably well eventually I'll move on to things like photoresist but for now this is more than sufficient and is just so much faster and easier once you've got the design cut out I cover it in green painters tape clean a microscope slide with acetone and then remove the backing paper the green tape holds all the pieces in place so that you can transfer to the slide in proper alignment then just stick the slide on to the vinyl and smooth out the wrinkles then carefully peel off the green tape and whichever part you want covered in metal remove the vinyl from that area after these are coated we can just pull off the vinyl to reveal our pattern a quick note though is at least with this vinyl you can't go back and put another layer of it on to the sputtered metal even after soaking in acetone the adhesive just doesn't release from the metal which ruins the surface so you need a sequential method which we'll talk about more in a moment the other downside with this is that the vinyl out gasses a lot so as things heat up and the volatiles and the adhesives start to evaporate away the pressure rises and eventually you get out of the range where sputtering works well I just let the system pump down to about a hundred and fifty millet or then turn on the power and let it sputter for a bit when the flow starts to go positive from the pump getting overwhelmed by the released gases the pressure starts to rise and I turn off the power and let it pump down again just like in the last video once the system is initially pumped down during a new run I'll flood the chamber with argon and let it pump down again to remove as much water contaminants and reactive gases as possible and replace them with ideally pure argon I'll usually do two or three of these back fill cycles to make sure that the system is nice and clean before getting started then I'll leave it alone for fifteen to twenty minutes so that any of that sticky water vapor has time to leave but after that I don't usually add more argon doing the sputtering process for the reasons we discussed earlier when I first got the silver working one of the first things I did was pick up a pair of uncoated glasses so I can make my own sunglasses just because I thought it would be fun I mean when you've got a magnetron you use a magnetron so I popped out the lenses added a little vinyl sticker of the Avatar Fire Nation symbol because I'm a huge nerd and then one lens at a time coated them in a thin layer of silver afterwards the vinyl was carefully removed to reveal the pattern the name of the game was sputtering is process condition control and making two things identical is very challenging in the end I did manage to get it pretty close by just timing how long I was doing each run and watching the light level drop to about the same amount each time though one lens did need a quick top up the metal coating is pretty delicate so to protect it I made a little spin coater out of a computer fan I masked off the front face and edges with painters tape and then gave each lens a quick coat with some clear acrylic spray it took a lot of trials to find the right spray finish to give a proper clear smooth coating but eventually I settled on the acrylic after that I popped the lenses back into the frames and I am so pleased with how these came out the lens itself is made of polycarbonate so it blocks UV and the metal works really well is shades one interesting thing I've noticed is that when you hit the power during a run often there'll be a big spike in pressure and then the pressure starts to drop or when you turn the power on the pressure just drops immediately part of what's happening is that when the power is on gas molecules are attracted to the base plate and eventually get too close to the magnet and are sucked into the hot plasma area at this point they get accelerated at the base plate and crash into it especially for reactive things like copper or titanium the molecules react with the metal and then stay put so the pressure in the chamber drops as there's now less stuff floating around there are actually special pumps called ion pumps that do this on purpose and can pump up too many litres of gas per minute for really big units but eventually new contaminants overwhelm this effect in my system another option is to have a secondary chamber that literally just sprays titanium at the walls which will rapidly react with anything in the chamber and act as a remarkably good vacuum pump with no moving parts we'll look at both of these effects hopefully in a future video when I do the next round of upgrades now for metals that are cheap enough to get large pieces of just using them as a base plate works well but what are the things like gold or palladium that are extremely expensive well the professionals just buy a giant hunk and suck up the cost but it's not technically necessary instead I'm using the lossy nature of my chamber to my benefit because I know that titanium won't sputter no matter what I seem to do I can use a thin titanium sheet as base plate and then put a small piece of the expensive thing on top right at that spot where the plasma concentrates at first I prototype this using gold leaf but it just wasn't thick enough to work very well and would fly around as soon as I repress her eyes the chamber so I caved and I bought a tiny five gram piece of 24 karat gold because the magnetic field created by the magnet assembly under the chamber falls off quickly I had to use as thin of a piece of titanium and gold as reasonably possible to make sure that the gold would get hot enough for this to work initially I used a slightly thicker aluminum base plate but it was just so thick that the plasma ring wasn't forming properly to make the gold the right size I had to very carefully hammer it to shape which was probably the most nerve-wracking thing I've had to do lately initially the diameter was too small and it was too thick but after enduring the inferno of the plasma for a couple of test runs it was nicely annealed and worked more easily eventually using thinner titanium and thinner gold I got it working I think if you were to get a piece of say platinum or palladium foil that was already this thin and bigger than that central ring you could probably make it sputter this could open up all sorts of really interesting avenues for cheap coatings as a tiny piece should last ages because of how little metal is used in this process each run the first thing I made once the gold was working was my logo on a microscope slide and it came out amazingly well I'm gonna be giving away two of these at the end of the video so stay tuned for that one thing that's really fun is to do multiple different metals on one piece so by peeling off only some of the vinyl each run you can successively lay down different colors of metal which i think looks really cool only the first layer will be able to be seen through the glass so this way you can get intricate patterns without needing multiple masks for this piece I went silver than gold and then finished with copper even though it took some time this was a ton of fun to make got progressively more stunning the more layers were put down before the last copper layer I was cleaning off the back of the slide to reveal the pattern and like a turnip I snapped the slide so the copper layer had to be cut short when the tape I was using to hold the two pieces together finally failed I knew my time was limited so I was running the system pretty hot which meant a lot of oxides were getting formed but it gave this incredible metallic rainbow on the back which looks incredible even though it's just copper oxide thanks to the thin film effect we talked about in an earlier video you get display of vivid colors eventually when I switched a photoresist I'll hopefully be able to use multiple masks so that I can lay down detail on top of other metals but it's not easy with the vinyl because of the adhesive issue I mentioned earlier the photoresist will also give me a far higher resolution as this technique is only really limited by the resolution of the mask and can easily make nanometer features of angstrom thickness in a professional setting next I promise you metal hornets so here we go my friend brought me these from a nest he had to take down a few days ago and so they were still very fresh this is actually an issue as fresh translates to full of water which is the most annoying contaminant you can get in a vacuum system like this so at first the system wouldn't get past 500 millet or I thought for sure this meant that no metal would fly but when we hit the power sure enough I got the distinct blue glow of silver plasma before it quickly got extinguished as the chamber pressure continued to rise after a few of these cycles the Hornet was actually starting to get covered and the pressure was dropping in essence we were plasma drawing the Hornet gently while also covering in metal while it was fresh eventually we managed to get the pressure down to the usual operating levels as it dried out and got a beautiful silver coating on the Hornet now it looks like something straight out of black mirror I wanted to really see the detail up-close so I took a few pictures of it under the microscope and focused at them to make these awesome images this really emphasizes that every little nook and cranny and even the smallest hair and detail is covered in metal just for fun I also did a snail shell with a bit of vinyl mask and it came out as this partly metallized shell with some of the original pattern still visible I ended up doing another one later without the mask and using nickel metal and it was a noticeably grayer metallic coating while I was at it I also tried some cardboard and there wasn't so much as a scorch mark it took the coating had a gray matte finish from the very thin coat point is biological samples and objects with weird shapes or are otherwise flammable or delicate can all be fairly easily covered so long as they're careful probably my favorite part of all of this is that I was actually wrong in the last video I said all metal plasmas look white but that's not actually true thus far copper plasma is a beautiful green silver is vibrant turquoise and gold is a very pretty rose pink nickel was a deep orange almost neon I'm excited to keep trying different metals and I think we'll come back and try measuring the glow with a spectrometer to see the spectral lines of the different metals some of you asked about the conductivity of these coatings and yep they are in fact conductive the resistance can be a bit high if they're too thin but even the vinyl was made conductive after a thin coating was applied because copper is so cheap it's good to use if you're going for conductivity as you can lay down nice thick traces so for those of you wanting to make traces for circuits this totally does work though again I'd refer to Ben's video for more about that for me I'm less interested in making circuits and more interested in making electrode arrays for cell culture though I would make some circuits for micro fluidics here are two of the prototype arrays I've been working on they've only got 16 electrodes but that should be more than enough in an upcoming video these base plates will be turned into little petri dishes and we're going to try growing some neurons on them which ought to be a ton of fun for the first prototype I'm using a thick silver layer with gold on top to enhance the biocompatibility but eventually I'll either do titanium or platinum as the base layer if I'm going to continue to make electrodes like this and finally before we talk about the giveaway I just want to mention how incredible the chamber looks after all the layers of gold and silver and other metals it had a phenomenal rainbowy effect rich and deep yellows blues and pinks this meant I'm gonna have to probably regularly replace the chamber but considering these jars cost two dollars it's really not a big deal and now all of my friends are gonna be getting decorative homemade Voss's for Christmas so you know that's fun also the cookie cutter is now a vibrant mix of blues and purples from all the different layers of metal and metal oxides building up now about the giveaway like I said I'll be giving away two of these gold fought Emporium logos one to my patrons and one to everyone else so if you'd like to be entered in the giveaway click the link in the description or go to the link you see on screen for patrons and channel members I'll be posting a separate link for all of you it would get more entries for doing things like following me on Twitter or visiting my various pages while you're there feel free to subscribe and follow me but that isn't a requirement for the giveaway I'll announce the winners in the next video and send you an email to get your mailing address to close out I'll end on a book suggestion that several of you suggested to me after the last video it's called building scientific apparatus and it is legitimately the best book I have ever owned not only does it cover all of this in great detail it contains practical instructions for building almost any kind of scientific device be it lasers mass spectrometers pressure chambers and more so if this stuff interests you and you like building things you see on my channel I'd highly recommend you pick up a copy and to those of you who suggested it to me thank you a million finally as always I need to say a huge thank you to the patrons and supporters of this channel that are a huge part of what lets me work on projects like this if you've enjoyed and want to help keep the flow of science videos coming then consider kicking a buck or two my way and of course be sure to subscribe if you enjoy it and ring that bell to see when I post new videos don't forget to follow me on my other social media pages to see these projects and more long before they make it into videos that's all for now and I'll see you next time

Channel: The Thought Emporium

Views: 554,904

Keywords: science, physics, plasma, magnetron, sputtering, metal, engineering, how to, workshop, circuit, electronics, neuron, electrode, gold, silver, copper, coating

Id: EMzRZ4gXQ-0

Length: 19min 1sec (1141 seconds)

Published: Thu Aug 08 2019

Reddit Comments

[u/gnark]

The technique was developed coat the NASA space suit visors and other sensitive components with gold for maximum UV protection. The same technology later was used for the original mirrored sunglasses for RayBan and now is used to create dichroic glass for art applications.

[u/[deleted]]

make one big enough to sit inside of and become silver surfer

[u/NorthernScrub]

I really want titanium coated skin now.

[u/TheRealDirrtyDan]

Neat

[u/mediaphage]

I assume this is basically how I'd prep all my SEM slides back in the day, with the machine using a gold-palladium allow to sputter coat the samples. Of course, undergrads these days with their variable pressure SEM razza frazza....

[u/bmystry]

That's very cool.

[u/cjfrey96]

Sweet, we have a couple vacuum deposition chambers where I work. They’re pretty impressive machines, seeing a homemade one is awesome!

[u/Tech_Arts]

i like it . very interesting

[u/tamarockstar]

This guy's voice sounds a lot like Gamer Meld.