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Kapton: Miracle Material with a Tragic History
- PaulHoule 6y agoIf you see a picture a satellite wrapped up in what looks like gold foil it is probably Kapton film with aluminum coating on the other side. It is an expensive polymer compared to BoPET (a.k.a. Mylar) but it doesn't have the complex production complex. Mylar films are stronger but Kapton holds up better in the space environment so it is still the #1 choice for solar sails.
- johnwalkr 6y agoThere’s typically about 10 layers, each an aluminized plastic (Mylar or kapton). Usually the outer layer only is kapton since it’s more resistant to degradation from UV light.
- PaulHoule 6y agoI bought mylar films for about $1 a piece that cover some of the windows that get the most insolation on hot days. These are claimed to reflect 90% of sunlight and the feeling on my skin and my camera's exposure meter agree with that. I think each layer of 'space blanket' on the satellite has about the same transmission as the Wal-Mart space blanket, so with 10 layers you are decoupled from the Sun and resistant to micrometerioid scratches, spots of corrosion, etc. There is the UV-light problem but also atomic oxygen and other reactive species out of equilibrium that will eat some materials.
- wombatmobile 6y ago> it doesn't have the complex production complex I wondered about the manufacturing life cycle dynamics of DuPont's Kapton, particularly after reading this in the article: > Planes built since then generally use TKT, which is Kapton with two thin layers of Teflon to provide better resistance to mechanical abrasion and water intrusion. Would a measurement of the complexity of the production complex include the part where they dump the untreated toxic manufacturing waste into virgin streams in West Virginia, or would that be an externality? I recently saw a film produced by Mark Ruffalo that told the story of the West Virginia farmers whose stream was poisoned. They had to spend 7 years fighting DuPont's lawyers for justice, and then they died of cancer. Dark Waters trailer https://www.youtube.com/watch?v=RvAOuhyunhY https://www.youtube.com/watch?v=RvAOuhyunhY
- PaulHoule 6y agoTeflon is bad enough in terms of persistent organic pollutants. The PET in BoPet (Mylar) is one of the most environmentally favorable plastics in practice used to make plastic coke bottles that look like coke bottles also as "polyester" fabrics. The "Bo" is the part that looks complex to me in that mylar production involves a careful process of stressing it in two different directions while annealing it. It is funny because I have been tracing out the path to manufacture large Kapton/Al films using asteroid materials. It is not hard at all to find an asteroid with the resources, but the trick is building a 'chemical factory factory' that can turn space hydrocarbons into plastic films, assembling that -- the Chinese think they could build a sunshade at L1 Sunward for $60 Trillion with Long March tech, maybe SpaceX can do $5 Trillion with Starship, but to make it cheaper than that you have to make it from minor planets and turn all the 'difficulties' such as 'working into zero gravity' into opportunities such as 'easily handle films larger than New Jersey'.
- unchocked 6y agoI'm also working the planetary sunshade. Any source for the Chinese $60T price point?
- PaulHoule 6y agoThis paper describes a sunshade launched from a large expendable rocket of current technology https://journals.sagepub.com/doi/full/10.1177/1687814017719227 https://journals.sagepub.com/doi/full/10.1177/16878140177192... The $60T is my number based on the guess that the Long March 5 costs about the same as similar western rockets.
- SAI_Peregrinus 6y agoIt's also used as a tape. Very, very handy to hold down parts & wires when soldering, since you can get it right next to the iron and not have any melting/burning issues (with most electronics solders).
- dfee 6y agoThe article describes numerous crashes associated with Kapton, beginning with a story about a passenger plane where hundreds perished. It also mentioned a short circuit on the launch of the Columbia Space Shuttle, and military planes. When used as an insulator where it can rub or be exposed to moisture: you’re going to have a failure at some point. What’s alarming then, was the conclusion: > Still, hundreds of planes take off and land every day with Kapton insulated wires routed through every nook and cranny, some almost impossible to reach for inspection. And even when wire bundles are accessible, inspection comes down to a flashlight and a Mark I eyeball, looking for that cracks that might be lurking.
- x3haloed 6y ago> inspection comes down to a flashlight and a Mark I eyeball, looking for that cracks that might be lurking. Where is our reassurance that everything is OK now??
- nitrogen 6y agoI don't know if such things are used on passenger aircraft, but I've heard that fighter jets use time domain reflectometry to detect potential faults in wires, and how far along the wire the fault lies. Even a small nick in the insulation is supposed to change the impedance enough to create a detectable reflection. At least some gigabit ethernet interfaces have built in weaker TDR that measures the length of each twisted pair, but I've only ever had one computer that showed that info in the BIOS/UEFI. So, maybe if TDR is used for inspection, we can rest assured.
- toast0 6y ago> At least some gigabit ethernet interfaces have built in weaker TDR that measures the length of each twisted pair, but I've only ever had one computer that showed that info in the BIOS/UEFI. I've seen this info in the Realtek NIC diagnostic tool for windows (on one machine, anyway), and I've got a couple of semi-managed switches that show a line length estimate which I assume is based on similar measurements.
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- tibyat 6y agohonestly, read the article, not the comments here. a bunch of people showing off they know something about kapton, repeating what's already in the article.
- numinary1 6y agoKapton insulation was not shown to be the root cause of the crash of Swissair 111, nor was it entirely ruled out. https://www.tsb.gc.ca/eng/rapports-reports/aviation/1998/a98h0003/a98h0003.pdf https://www.tsb.gc.ca/eng/rapports-reports/aviation/1998/a98...
- TwoBit 6y agoI read the report and it seems to put most blame on all the flammable materials present than the initial arcing event.
- tyingq 6y agoKapton is something you've probably seen if you've opened up a laptop. It's the most typical material used for flexible pcbs: https://raypcb.com/wp-content/uploads/2018/03/35e7d51a831f153.jpg https://raypcb.com/wp-content/uploads/2018/03/35e7d51a831f15...
- pfdietz 6y agoPerhaps the solution is to go to optical fibers, and just have a small number of power cables with better insulation.
- areoform 6y agoAs PaulHoule has pointed out, https://news.ycombinator.com/item?id=24179043 https://news.ycombinator.com/item?id=24179043 , Kapton is the final "gold foil" layer in a foil sandwich to insulate almost all spacecraft, inclusive of the LEM. It was used extensively as insulation in almost every Apollo subsystem, including the Command Module, and it became a small tradition to take pieces of the foil with you after splashdown. A final keepsake after a mission gone well. Others adopted the tradition and pilfered more pieces of foil. They were fairly indiscriminate. And spread the fruits widely. You can buy your own from places like here, https://shop.minimuseum.com/products/apollo-11-command-module-foil https://shop.minimuseum.com/products/apollo-11-command-modul... Personally, I would have loved to own a piece of our robotic explorers. Kapton has been used in incredible ways in craft like New Horizons. It's possible to overheat instruments in an object millions of miles away from the sun! https://mattcbergman.com/2015/08/02/new-horizons-thermal-control-system/ https://mattcbergman.com/2015/08/02/new-horizons-thermal-con...
- c54 6y ago> Mark 1 Eyeball Gonna have to remember that one
- mark-r 6y agoGood luck with your Mark 1 Brain.
- 082349872349872 6y agoMark I brains suffice to make incised graffiti. Although the data density is pitiful, the observed retention lifetimes beat tape storage. (At a stretch, eyeballs might be Mark I, as they obviously haven't yet been patched to move that interconnect bundle out of the high-res region. Brains have enough legacy layers that they're probably Mark V at least...)
- Rebelgecko 6y agoKapton tape is also a great example of how Amazon algorithmically enables knockoff and counterfeit goods. I recently bought the #1 result on Amazon for "kapton tape". A banner on the item's description proclaimed that the listing was "Amazon's Choice for Kapton tape". So I ordered it without doing any more due diligence. When the item arrives, it turns out that it isn't Kapton. It's a knockoff called "Koptan". In their defense, the actual vendor's description doesn't call it Kapton, just the "Amazon's Choice" banner. Kinda sneaky The tape I got looks a lot like Kapton. But is actually the same thing? Who the fuck knows. At the very least, my house hasn't burned down yet
- rkagerer 6y agoThe comments beneath the article have some discussion about Koptan / Krapton.
- dapids 6y agoI bought a roll direct from 3M a few weeks back. Was well over $40. It would also appear they don't call it kapton, but instead thermosetting adhesive. Checkout 3M 5413 AMBER. Larger rolls can cost upwards of $300, not cheap stuff.
- dapids 6y agoI should also warn, if you decide to take the risk buying this fake krapton garbage, you do risk an electrical fire. Unless you yourself have tested the resistance this tape provides versus the real deal, DO NOT assume it is an insulator!
- LeifCarrotson 6y agoDigikey is one of the primary vendors of 3M, and well known for reliability as a counterfeit-free distributor. https://www.digikey.com/short/zrz730 https://www.digikey.com/short/zrz730 Also, even if you've not used them before or have no need of kapton tape, take a look because their parametric search is one of the greatest I've seen, and makes Amazon's Choice system seem awful in comparison.
- B5C8ECB24DB47D1 6y agoAlso commonly used as vacuum window in X-ray facilities/setups. Probably one of the best ratio mechanical resistance / low absorption over a large energy range.
- nickbauman 6y agoKapton is also inside many nuke plants in the US, too. What could possibly go wrong?
- S_A_P 6y agoI was a huge car audio nerd in the late 1980s/early 1990s. One bullet point you could expect to see on most subwoofer spec sheets was 'KAPTON' voice coil former. I often wondered why that fell out of favor, but it seems that we know the answer... Most kilowatt subwoofers now use aluminum or copper voice coil forms for what I can only guess is that they are just better...
- analog31 6y agoKapton was an improvement over paper and phenolic, due to higher heat resistance. It's still widely used, e.g., in musical instrument speakers. I could see how aluminum and copper could be further steps along a similar progression.
- unsrsly 6y agoKapton is an outstanding substrate material for flexible printed circuits. It has one of the lower dielectric loss tangents available, and this becomes important in RF and microwave applications. However, PTFE is better.
- peter_d_sherman 6y ago>"Studies showed that Kapton was far from the ideal insulator everyone had hoped it would be — it tended to develop circumferential cracks from the slightest of nicks, exposing the conductors within. Kapton is also easily degraded by moisture, exacerbating the problem in humid environments or areas of an aircraft subject to moisture, like galleys and lavatories. Once the insulation is compromised, arcing can occur, which leads to charring of the Kapton. This changes the insulation’s dielectric properties, turning it into a conductor. In some cases, this led to overloaded circuits that were not detected by circuit breakers, since the insulation was carrying the excess current rather than the conductor." [...] >"Planes built since then generally use TKT, which is Kapton with two thin layers of Teflon to provide better resistance to mechanical abrasion and water intrusion." PDS: TKT sounds like a much better material, from a material science perspective...