Underwater laser cutting and silver sintering to make ceramic circuit boards
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- เผยแพร่เมื่อ 24 ก.ย. 2021
- Thermal stress cracking can be completely avoided by CO2 laser cutting thin alumina sheets underwater. I also show how to formulate and apply silver paste, then sinter in a kiln to produce double-sided ceramic printed circuit boards with conductive vias.
60W CW CO2 laser at 80% power. 10mm/sec. Standard lens focal length (50mm). 2mm water above ceramic. 180 passes to cut through 0.75mm thick alumina.
Silver paste: 97% silver powder, 3% glass powder by mass. Particle size 1 micron or less. Add poly vinyl alcohol mold release until desired consistency reached.
Paste applied with 4 mil thick vinyl stencil. Dried in air 10 minutes, then rapidly brought up to 900*C, held for 10 minutes, then rapidly brought back down to room temperature. Total cycle about 45 minutes.
I measured electrical conductivity of the finished traces from my process with vinyl stencils: 4 milliohms per square at 10 micron final thickness. This is pretty close to the Dupont published spec ( less than 2 milliohm/sq at 16 micron thick)
Underwater CO2 laser cutting reference: sci-hub.se/10.1016/J.JEURCERA...
60W laser cutter: www.ebay.com/itm/294386493292
Ceramic sheets at McMaster: www.mcmaster.com/alumina/nonp...
Ceramic PCB prototypes: ceramic-pcb.com/product/alumi...
Quickfire kiln: kruegerpottery.com/products/p...
Raspberry Pi picoReflow oven controller: apollo.open-resource.org/miss...
Silver powder: www.ebay.com/itm/122525930519
Glass glaze: www.amazon.com/dp/B0044SCR6O
Macor: www.mcmaster.com/materials/ma...
Dupont silver paste: www.dupont.com/content/dam/du...
Binders for ceramic powder: digitalfire.com/article/binde...
PVA mold release: www.tapplastics.com/product/f...
Very complete study of laser machining of ceramics: www.research.manchester.ac.uk...
Applied Science on Patreon: / appliedscience - วิทยาศาสตร์และเทคโนโลยี
"Maybe I should do that more often...."
YES YOU SHOULD.
I have never watched your content and not been fascinated and intrigued- even with subjects that I'm not that interested in.
I think if we hired a crew to follow him around everything in his life would be interesting enough to watch!
This makes me appreciate the science behind making the ceramic dielectric barrier ozone generator plates with their metal electrodes.
If only he had a radioactive MRE heater!
..I like turtles
@@br6768 I got bronchitis! Ain't nobody got time for that!
@@br6768 no you don't.
The self-soldering at the end wasn't bad either.
I would enjoy seeing videos about your tools, especially the custom electronics / custom programmed devices. I feel like those are the ones that I would be the least likely to go out and make (mechanical engineer here), so seeing your methods would be useful.
they are the ones I'm most likley to make, so it'd also be super usefull lol
I'd be fascinated to see a video on your kiln controller, as well as your other tools.
Agreed! Short videos on the tools would be really interesting, and a great resource for anyone who would want to make something similar in the future.
I would also like to see this, with no qualiifications.
+1
My professor said before doing research first to go to a library. because 99% of the time someone is already dome in before. your video made me remember his words that i heard more than 15-20 years ago.
Thank you.
Loved that you took so much effort to find this method! As for ceramic PCB, the easiest way is to cut it is the "green" state (LTCC). You can then also easily create multi-layer boards and drill vias using a laser. As for your question about the crust on your silver: it is silver oxide. You can avoid this by heating in a vacuum oven. This is not complicated, just use a small surplus dental oven. These generally have a vacuum seal and can be bought very cheaply (and are programmable)
Or flood the kiln with a gas like argon maybe? Just a small constant flow.
Would it work if you keep a nitrogen atmosphere by releasing N2 inside the oven through a coil?
Thought Argon too
@@dparker12997 Yes inert gas like Argon would work too. I'm not sure about pure nitrogen, since formation of silver nitride is a possibility.
I imagine you could also chemically remove the silver oxide with dilute acid (nitric, for solubility) or ammonia. You might also be able to reduce it.
100% I'd like to see videos of your raspberry pi kiln controller and any other hacked together tools you use. Your ingenuity is the reason I'm here.
I love how the solution to both of the biggest hurdles in this project was... water. Plain water. I for one would really enjoy a video on the equipment you put together, using reflow software for that kiln is genius!
One of natures most potent solvents. And they call it that because look how much it solves! ;)
Using reflow software to run the kiln is pretty obvious in hindsight but I wouldn't have thought of it
Water? You mean like in the toilet?
@@AtlasReburdened but I don't think that has electrolytes.
Yeah, well the water is really universal thing in this universe.
I’d love to see videos going in depth about your tools and setups
I wish I could upvote this more than once
It's hard to think of anyone who wouldn't...
Used to work at a company that manufactured thick film substrate circuits, including screening resistors (this was in the seventies). DuPont was the place where we got our inks from. The silver conductive inks that we worked with actually included 7% or more of palladium or platinum. I recall the binder being a petroleum base. Over time the ink would dry out/get thicker in the large cold cream size jars they would come in, so we would have to add a relatively thick thinning agent to bring them back to a screenable consistency. We used 400 stainless steel mesh stretched across relatively small steel frames that fit into a semi automated screen machine. The largest ceramic we would screen would be a little more than 3 square inches. Most were the area of a 14 or 16 pin dip package. The kiln was a multi zone chain linked belt that took 35 to 100 mins for a substrate to be fired, depending on what particular inks were being fired.
On a separate question, what about cutting gorilla glass?
You know how if you actually break the glass it shatters? I bet that would happen.
Another incredible technique that my professors told me was way out of the scope of DIY. Your videos never disappoint. I'm thinking this + thin film sputtering + metal to glass/ceramic soldering = DIY ultra stable resistors??? A certain German volt nut might be interested...
You can't just mention a person like that and not name them!
@@alexcivitello3165 Pretty sure they mean Marco Reps: th-cam.com/users/MarcoReps
You need a zero TC substrate for that, which aluminia is close to, but it still expands slightly with heat.
@@SeanBZA As mentioned in this video, the cutting works well on fused silica. Is that close enough?
That’s a very interesting proposition. You’d need to deposit a metal alloy that expands at the same rate as the substrate for stability, and ideally both those rates would be zero. I wonder what the cheapest materials would be?
20:30
Yes please!!!!!!!
The highlight of these videos is always the part where you mention how easy these things are to make at home. "The only tools we're going to use in this technique are a CO2 laser cutter and a small kiln." Always cracks me up.
LOL, the self-baking board is genius! Also cutting ceramic boards under water, of course, but that's too amazing to be funny.
Yeah, I recently saw Carl Bugeja do it with plain FR4. th-cam.com/video/ZChSbpBbrt4/w-d-xo.html
Spitballing here, but couldn't you cut grooves into the surface like you mentioned was possible with the water+CO2 laser combo then use the groves for the traces? Then you could control the thickness of the traces and not need a mask, just put the paste on, and wipe it off allowing the paste to get stuck in the grooves.
Kinda what I thought was going to happen at the start.
I would imagine you probably could, but it would probably take a lot more time cutting the grooves with the laser than it would using a mask. If you Needed a completely flat board with inlaid conductive traces, I bet you could do it though.
@@keithyinger3326 Long yes, but that will also make it "set it and forget"-setup.
A video on your kiln would be extremely interesting.
And you'll probably get a lot of interest from the metalworking community in that as well, heat treat ovens aren't cheap so a good DIY version would probably be of significant interest to many.
At the rate you're going you will discover something novel. And even if you don't I am certain one of the many people you've inspired will. You're a positive influence.
I've heard him some times saying something like "I found this functions very well, and I could not find anybody have done this before..." I'm pretty sure he has already found new things.
Yay another Applied Science video :D
this channel is one of those rare gems.
As always, something complicated that requires high technologies is implemented in home laboratory conditions. Great, awesome work!
That spirit is why I love this channel!
not to mention unravelling analogues to secret formulas.
Been a while since I clicked a notification this fast. Applied Science is guaranteed interesting high-quality content :)
MACOR shrinks A LOT when you fire it afterword.
In order for the glass to fuse in properly, its coefficient of expansion must match that of the alumina, or it will form micro-cracks.
There is a process using manganese & molybdenum to form metal-to alumina bonds. This is used in the manufacture of argon laser tubes (mentioned in some Coherent patents), & is very robust against stress & CTE mismatch. There is also a "silver palladium" process used by RCA in the 1990's to manufacture thick-film hybrids.
I'd love to see more details on the kiln, with an eye towards application to a diy metal foundry.
You will be the most favorite person of the vintage watch collectors community soon! This was exactly what they have been waiting for to bring life to the old digital watches, which were suffering from corroded Ceramic PCBs.
The self-heating reflow was hilarious. :)
Your videos are always a treat, and I think a lot of people would appreciate some how-to videos on techniques and tools you've discovered that made projects more convenient.
6:20 - darn! I thought you stumbled on something truly novel. Still pretty cool that you figured it out by yourself 👍
I’ve no experience of laser cutting, so that was truly interesting. Thank you. Silver paste sintering I’ve done quite a bit of though and I’d love to hear if you’ve tried sintering to fused silica. It’s a little different…
Incidentally, after scrubbing your traces to remove the oxide, lift the residue off the alumina by a quick rince in nitric acid. Another approach is to use a vacuum furnace to avoid forming the oxide layer. Used small dental furnaces can be found for very little money.
It might not be silver oxide. That oxide is still conductive.
Listen man, I would literally watch just about any video you would make. I would DEFINITELY watch tool videos!
Hi Ben! Thanks for making my Saturday night!
So if you could etch pockets very accurately can you use the laser to directly etch the circuit board and then fill the "pockets" with the silver paste? Yeah it would take longer but you eliminate the step of cutting out and peeling vinyl and it would probably be better for more accurate work.
As usual, this is awesome!
I was thinking the same, plus you could control the thickness of the trace dependant on current requirements.
All of this is true, but it takes a lot longer!
that would make sunken pads though which are no fun on smt boards since the silver shrinks like 10:1 from paste to trace when fired
Hey, the colour of the plain glass is probably due to sodium vapour emission. The fused silica won't have that, it also won't have inherent lattice defects, maybe that's why it cuts better.
I have done some rudimentary material testing, and I have to say kudos to you for going through all the effort to figure out the silver paste and get around all the stupid proprietary secrets, and sharing it with the world.
The value of processes that you show are amazing. I almost fell off my chair when you disclosed the inclusion your reflow heater. If you are still working for Google I hope you are very very well paid. Thank you for being so generous with what you do. I'm an old guy and when I was a young boy I used to hang around in the house of Claude Shannon. Your thinking reminds me of what was going on at his house.
Consider cutting troughs and valleys for "in-board", components, resistors, caps, battery, antenna, etc. using graphite, electrolytes, etc.
I highly second this. Kinda like a 2,5D sandwich (maybe even more layers) structure with loads of integrated circuit-stuff as a neat compact block.
Ben, for the oxide build up, you can use argon, or an even more reducing gas (e.g. "forming" gas). There's something called an Ellingham diagram that can be used to determine the oxide stability in different atmospheres.
Yes! Please make videos about your tools. No problem if they are shorter videos, because they will still be so informative and useful. Thanks for all the time and effort you put into your channel.
Definitely a video on the kiln pi. That's a very useful build. But tool videos in general are always appreciated.
This is always the most incredible channel - every video has multiple points where I'm amazed you managed to get something to work, followed by enough science that I _understand_ how you made it work. Great job as always!
Would love to see a more in depth look at the equipment and processes on a second channel or something.
Yes, I would love tool videos, even one offs
Yes, absolutely, the Raspberry Pi 119 v kiln! And other handy tools! 👍🏼😎✌🏼
Hi Ben, I wonder if the glass coating after the sintering step could be removed by a quick etch in HF? Depending on how thin it is. Silver is somewhat attacked by HF, but much more slowly than glass. If there's only a few-micron thick layer due to surface tension of the molten glass, it should be removed quite quickly. Alumina is also attacked by HF so you might have undercut issues if the etch time is too long.
P.S. I think it would be neat to look at the traces before/after sintering with your SEM!
Feasible to sinter in vacuum or inert atmosphere?
@@illustriouschin I was thinking there's an oxide layer too. Argon is fairly cheap.
We definitely need a follow up from Ben!
@@illustriouschin I think even if you do the sintering in vacuum, the molten glass will flow and coat the silver particles due to surface tension. Maybe better temp control so the glass only softens and doesn't actually melt? That's what's supposed to happen during a sintering process, but the shiny/smooth appearance of the traces coming out of the kiln suggest that the temp is too high and the glass does fully melt.
What a *SUPER* useful video! You’ve opened up an entire new class of material for makers and scientists!
I’m actually not at all surprised that the technique didn’t work for glass: Alumina has a relatively high thermal conductivity (anywhere from 0.5 - 1x that of steel, depending on the alloy and heat treatment). Thanks to that, the thermal energy can be quickly conducted away to the surrounding areas and transferred to the water, so it’s acting as it’s own heat sink. Glass is about a factor of 30 less thermally conductive, so the energy can’t dissipate. Fused silica has very(!) low thermal expansion, almost a factor of 10 lower than alumina, so there’s way less thermally induced strain to begin with. (I suspect you might even be able to cut it without the water, have you tried that?)
Anyway, a fantastically useful video, thanks!!
I really love the "let's not dumb it down" approach.
Ben, You Da Man !! You bring us simple solutions, for complex problems.
And you do this, as you take us down many if not all avenues in the world of science ! Awesome work and thanks for sharing !!!
I really appreciate you giving me all this advice as if I was ever able to reproduce anything of what you’re showing here. But it makes me feel like I could :) Fantastic video.
Your videos have entertained me for years. Though I always have appreciated how thorough and well documented your processes are, I have often wished for more frequent postings at the potential sacrifice of a polished final product.
That aside, I would enjoy learning about the tools and equipment you employ. Some of my most utilized tools were discovered from people that I have worked with or followed on TH-cam. Always anxious for an opportunity to learn something.
Thanks!
I swear this dude just picks cool words out of a hat, puts them together and figures out a way to make it work.
This is mind-blowing, and you act like it's no big deal! You show TWO amazing DIY techniques!
I would absolutely love to see a video on the raspberry pi kiln controller. I've been trying to figure out a cheap way to make a glass annealing often and that would be a perfect solution
For the cleaning prep: use the original cut file to make a "cleaning stencil" to lay on top of the board during cleaning... it will ~mask the non-trace portions of the board
couldnt you try some photolithograph material? you would need some that survives the sintering temps but can be burned away with the laser cutter during cutting adding some more passes while its already in there wouldnt be a huge deal and there would be no alignment problems after the sintering you could clean as normal and when you smear trace material into the sourounding well you remove that masking material and all the dirt that is in there would be removed as well job done. maybe a higher melting metal that does not create bonds to your silver would work one that is chemically removable with a solvent that is not preferring the silver over the masking-metal
alternatively burn in pouches in the ceramic at the traces and use the photolithography mask idea in combination. add more trace so you can etch away mask and part of the trace later to ensure still having enough left over trace after wards. assumes that the material inside the trace is more usable (which the video suggests)
Definitely make more videos about the tools you create for your projects!
When a new Applied Science video comes across my feed I drop what I’m doing and watch it!
A great way to do PTHs I think. Easier than those expensice chemicals that the professional PCB makers use. And no expensive platinum catalyst required!!
It's been a while now, but I've had quite some success cutting and engraving Keraflex unsintered porcelain sheets with a CO2 laser in my lab. If I remember correctly the sheets are the same thickness, if not thinner, than what you are using there. They are fairly flexible in their "raw" state. You'll obviously need to sinter them, but the cool thing is you could shape them before firing. When laser cutting it in its unsintered state the cut line seems to sinter which makes the unsintered parts easy to separate. Be aware that the powder created in the cut line will wreak havoc on your linear guides and bearing surfaces, but I assume you're pretty familiar with that by now 😁
If the powder is a problem couldn't you combine the water technique to capture the dust?
@@dparker12997 the Keraflex porcelain sheets are not fired/sintered, and would probably dissolve in water. They might have some wax or thermoplastic binder, but I doubt they would last long in water.
The ceramic powder isn't a problem if the machine is thoroughly cleaned after use.
My plans for the week was to find ceramic plates of macor and machine them. Popped in to check my subscriptions and found the answers before even starting the week. Insane. Thank you!
This video is definitely a gateway for people DIY'ing ceramic PCB's as research papers, for all the solid info they supply, it's not the first place Average Joe's/Jo's look. Nice vid.
I would imagine most of the machining is actually from cavitation in the water. You could try adjusting the focal point to test this. As for the glass sintering, what if you used a potassium solution similar to how "gorilla glass" is manufactured, with the silver and glass powder.
blows my mind how powerful water cavitation is
To increase thickness using screen printing, you scoop the emulsion more times on the inside than on the outside, for example: you apply 1 layer of emulsion on the side that touches the substrate, and then apply two or more layers of emulsion in the side of where you put the "ink", this increases the thickness on the substrate side of the screen.
a drawing would help..
@@St0RM33 This here is one way to increase emulsion thickness, even though it's not the way I said, you will understand the terms that I used and how to implement them. th-cam.com/video/fwjo63Yq9Gg/w-d-xo.html
Also, the factors that he explain will help you further to increase ink volume on the substrate.
Tool Talk welcome!!! Making tools that work is often more satisfying than the work being done for us mere mortals! :)
To be honest, I came for some interesting/edutaining (but won't make by myself) stuff, but lasercutting glass and RPi based reflow oven is just what I need!
What about having a constant flow of water over the point of laser contact? Kinda like how some CNC machinery has a constant flow of coolant over the piece being milled via a pump. You should be able to keep the alumina cooler and be able to keep the thickness of the water flowing over it at a constant by varying the flow rate.
Would a mist of water be good enough?
maybe flow a refrigerant gas over it.
That would probably cost. Have to look at affordable options.
A water mist might cause more optical interference and a coolant would probably do the same. A gas refrigerant would be costly or complicated if using a gas recycler. The idea is to remove the heat as quickly as possible without degrading the power of the beam.
there is one channel of guys who produce interesting laser setups, they use a stream of water, quite a steady one but in principle like water jet cutters, and it serves as optical conductor for the laser beam and it cools the cutting place - so basically a situation is similar that water cover Ben used. But laser there is one of the pulse lasers, not sure co2 can do that, and there probably would be microbubbles as well but really small ones. With non-pulse laser, if there is no bubble then it probably won't work, essentially just because it does not provide enough power. The guys I was talking about are Avonisys, and they have some youtube channel with the name. Content there is interesting enough, applications so as they have some fun as well, only regret I really wish they do a bit more and more often
I'd try using a melamine foam sponge (magic eraser) to get the smeared silver off.
This person is more efficient than some companies whole r&d departments.
Always super cool stuff and interesting. Thank Ben.
Look for silver clay, used for making jewelry.
Sure worth trying
Nothing wrong with elective credits from underwater basket weaving lol. I’d love to see a 400 level version though
Outstanding material, as always!
Incredible detail! Thanks for doing this
Now I'm wondering: Could you cover the whole board in paste and then sinter it with the laser on low power? If it works, you could sinter only the traces and remove the excess unsintered paste...
The silver is too reflective, Co2 layer cannot sinter it.
How about cnc media blasting it or would that be too crazy.
Think it more likely to prepare full-coated boards -- which can then also be electroplated up to whatever desired thickness in copper or silver -- and just etching with nitric acid, maybe some HF added to help deal with the glass.
Uh, give or take the downside of plating copper over silver, which leads to porosity (Kirkendall effect). Upside, it can be annealed no problem (do use a reducing atmosphere!), which could give even better conductivity than straight plated copper (which is a bit worse than pure annealed, due to internal stress and whatnot).
....just a thought, but have you tried to use the laser to "burn" the glass/oxide layer off of the cintered boards?
shoot a laser at a mirror and tell me how it goes
@@natalieisagirlnow its not a mirror until the top layer of glass/oxide gets obliterated and removed though. that top layer makes it opaque, which is why i was suggesting it.
it MIGHT get a "cleaner" end result, as opposed to hitting it with scotchbrite pads....or it could not work at all, and im an idiot, lol.
@@stapuft I'd say the main issue I'd be concerned about would be collateral damage to the ceramic substrate. Probably have to do the etch underwater again.
@@MysticalDork oh definitely, even if just to be safe, we know it does work to keep the ceramic from cracking.
Ben, you just solved a problem that unlocks a huge impediment to my research. You content is more than just entertainment.
On the topics such as the kiln controller, I think some short videos covering topics like that could be equally entertaining and usefull as your primary content. I would love to see them. Though, if you are still hesitant to put them on your channel, perhaps we could beg you to have a second channel for them. I see no reason to have them on this channel, but if you do, it's an option.
You Mr. Cutie are doing amazing things!
"Cut Ceramic sheet with this one weird trick" sounds like exceptionally well targeted clickbait
Meant for appropriated audiences only
I feel like 2/3 of Applied Science videos could put "one weird trick" in the title and it wouldn't even be clickbait, because there's a genuinely weird and extremely useful trick plus a bunch of practical details to make it work.
When you were talking about needing very fine glass powder, the first thing that came to mind was fumed silica. Have you experimented with this? Or was it "too fine"?
One potential issue I can see with that is that fumed silica is just that: pure silica, not glass. It won't melt before the silver reaches its sintering temperature. (Silver melts at 1763 degrees, and silica melts at 3110 degrees F.)
I suppose you could include the other ingredients of glass (sodium oxide and calcium oxide) to form glass in situ, but that's a pain.
@@MysticalDork That may be the case, but in the video, he suggested his "intrepid viewers" to figure out how to sinterer the silver onto the ceramic with a laser. I'm thinking that this might be a good use-case. Combining the silver and silica into a water-insoluble binder and running it under water, or perhaps mixing it with a black pigment and use a flash tube to flash bond the silver-silica mixture using mylar tape as a sort of mask to protect the ceramic.
Man, I love watching these videos! thanks for sharing another one!
lovely process of rediscovery!
I just had an idea. You mentioned that selective removal of ceramic was possible, could this be used to remove the need for screen printing? Just remove channels where the circuitry goes and spread on the paste.
Oooh, that's interesting! Would also be useful for higher current traces.
Only concern is that the ceramic is pretty porous, so it would be hard to remove all of it from the top surface.
@@BRUXXUS masking should solve that, need something thin, non porus, removable by laser and removable in a kiln. Edit, a continuous layer that covers the entire piece of ceramic at the start of the process.
My thinking, too. That way, you might not even need the PVA binder. Or, if the channels are thin enough the silver powder might stick inside the "valley" without glass powder.
Why not make a separate channel for just the tools?
Can go more into their operation and have longer stuff and maybe from the hip more content. Worry less about not being entertaining enough, or to long/short. I love watching a person with skill use a tool but it's definitely not for everyone.
Could be called "applying science"
This channel is an absolute gem.
I think that you and your ideas are just GREAT! Thank You.
I've always enjoyed the long format of your videos, but TH-cam Shorts may be a good avenue to show tools around the shop!
Yes more videos
Anything you post is pure gold
Fantastic experimentation and explanation as always! Thanks for the video, sir.
I'm always amazed how far you take this stuff. Thanks!
I love that you walk us through the discovery process. I learn so much from that alone!
Amazing, thank you. Videos about tools and IT stuff always more than welcome!
You are awseome and a real role model! Thank you for your inspiring work and motiviating!
Fantastic video! Thank you for all the hours and fails that go into it!
This makes sense. I seen a video of someone cutting glass underwater with a pair of scissors. Without the water the glass would explode. With the water, they were able to cut circles & different shapes.
Really great work and documented to share with the rest of us. Videos like these are my favorite on TH-cam. Thanks for sharing!!!
A fused quartz board with ITO traces would be quite the party trick!
Definitely would look super futuristic!
I love your channel. I've learned so much. I really enjoy the way you research and try different things based on your observations and then modifying you attack. Man I wish I had a science teacher like you when I was in school. You really cultivate the curiosity in me.
Very cool! When you talked about how little was removed from each pass of the laser, what *INSTANTLY* popped into my head was 'laser-etched porcelain lithophanes'. You have *GOT* to try that!
wow this is an amazing way to make high temp circuitry!
Awesome, like always! I will give it a try on my 40W Co2 Laser. You never run out of ideas!
This was a delightful video. I laughed quite hard at the built in heater for soldering, I am very happy that you added that in.
I have etched (in air) all kinds of glazed and unglazed ceramic, glass, and metal (even polished metal) with a normal laser etcher, and never had any problems with cracking or warping. There are two secrets to success: 1) always use Raster Scan mode and 2) for the more difficult surfaces, coat them thinly in some paint-like material that is black in the infrared spectrum. (White Out typing correction fluid is IR-black, but I never tried it myself for this purpose.) I discovered these secrets very quickly because one of the first things I wanted to etch was the back side of mirror tiles. The opaque coating on the backs of mirrors is evidently black to IR, and what it does at high laser power settings is *it absorb so much laser energy, it flashes to plasma and ablates explosively, taking some of the glass or other substrate with it.* Fairly significant etch depths were easily achieved, such as several thousandths of an inch or 0.1 to 0.2 millimeters. At just the right laser power setting, only the black coating and the very thin metalization were removed, while the glass was left essentially unscathed. Good luck to all in your efforts!
So cool you found the paper describing the same method and mentioned it here. Science rocks.
I find that I really enjoy your current style videos where I learn things that I probably wouldn't learn anywhere else.
You. Rock. Just another in a series of amazing videos, shedding light where there was darkness before!