Kapton 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
I 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.
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.
Yes, I regularly order from them, but shipping via DigiKey hasn't been great lately where I live so I went with 3M. I also highly recommend digi-key for anyone's kapton needs.
Edit: spelling
> shipping via DigiKey hasn't been great lately where I live
I'm super curious where you live, approximately! I'm in Saskatchewan, and Digi-Key reliably gets me parts next-day, even when shipped DDP (they take care of all of the duty for me). For crossing a border, that's pretty incredible!
I’ve had to dump DigiKey since they use UPS exclusively, since I’m in Australia, UPS has one facility in my city. It’s a real pain to haul my ass out there because UPS have zero alternative arrangements over here. It’s delivery to the person/address or hold at the facility out in the middle of no where.
The only trouble we've had with Digi-Key over the last six months, with dozens of orders, has been coming too close to their end-of-day shipment cutoff. (It seems to be closer in practice to 7:30pm than their advertised 8 CT, but I'm not begrudging them that during this pandemic! This is avoiding restricted materials such as lithium batteries, flux, etc., as well as avoiding value-added items. Order those earlier in the day if you want them fast!) Most of our orders are overnighted, for what that's worth; I know the big distributors do treat overnights differently.
We have never seen a single issue with pricing not as advertised at small quantities, or a shipping mistake not directly attributable to the carrier.
Mouser has performed similarly well but is (and has always been) significantly worse with their cutoff. Again, they're nominally 8pm CT but 6 or 6:30 is more realistic if you're counting on it being here the very next day.
Both are amazing if you're used to crappier distributors, but you do pay for it....
Yeah over the past 3 years about 1/50 parts i order on digikey results in "surprise! that part you already paid for a few days ago was actually backordered because we didnt update the listing so plz wait 2-3 months thanks." quite irritating when working on a schedule of a few weeks. The wasted time reordering only compounds with all the associated procurement beurocracy on my end. I can't imagine they jerk around their high volume customers like this.
I like DigiKey, but sometime they're neither convenient nor competitive.
Food for consideration: since 3M is a ECIA member manufacturer[1], if the source isn't direct from the cow's mouth or one of their authorized distributors, it's prima facie suspect in my eyes and cannot be trusted on anything with skin in the game.
I 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!
And the problem is kapton is just one of many polyimides, (pmda-oda) there are other others like P84 (btda-tdi/mdi).
But nobody knows the generic name (the acronym isn't even in the wikipedia article) so fly by night vendors use 'kapton' wherever they can get away with it.
(and as with teflon, iirc they sell other polymers under the name of kapton too)
As PaulHoule has pointed out, 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.
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-con...
If 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.
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.
Teflon 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'.
There’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.
I 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.
The 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.
> In the 1970s, the most common wire for aircraft was Kapton-insulated wire. Kapton is a DuPont trade name. Today, aircraft wiring is typically insulated with Teflon, Tefzel, Cross Link Tefzel or TKT (Teflon-Kapton-Teflon). Typically, the AVS for an aircraft lists the type of wire insulation that will be used throughout the aircraft. For example, the OEM might decide that TKT will be used, with some exceptions such as radio cables and Teflon-insulated wire in boxed assemblies.
I've worked with kapton tape (but never kapton insulted wire) and I can't imagine it being much good as insulation for wires.
I've also worked with lots of PTFE insulated wire and it was nice to work with, but only once you'd got used to its low friction.
No part of an aircraft is 100% reliable. Manual inspections are a fundamental part of keeping an aircraft safe. How do you know that the tires haven't perished? How do you know that a bulkhead isn't developing severe stress cracks? How do you know that the bearings on a control surface aren't just about ready to seize? Because the aircraft operator is required by law to systematically check every part of the aircraft according to a strict schedule.
Your reassurance is the fact that flying is the safest form of travel thanks to decades of diligent work by engineers, mechanics and accident investigators.
I 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.
Sort of unrelated, but a very interesting application of TDR on cables: in military, infrastructure, and certain other installations, a common security measure is a fiber optic cable woven into the chain-link fence or shallowly buried. Any deflection of the cable (e.g. due to a person climbing the fence) results in a subtle reflection in the cable. By knowing the layout of the embedded cable, not only can the event be detected, but it can be localized and used to e.g. trigger automatic pan of PTZ cameras. A major brand-name for this system is FiberPatrol but there are several vendors.
Unfortunately it is rather false-positive prone when applied to fences, significant wind loading can cause the chain-link to lash back and forth and repeatedly deflect the cable. The resulting alarm fatigue was implicated in the somewhat (in)famous case of the nuns as site Y-12. Nonetheless this application is very common at federal installations and also certain non-federal infrastructure installations, e.g. the legacy iron fences around Portland, Oregon's surface water reservoirs (where remote-controlled PTZ cameras appear to be used for rapid remote confirmation of FiberPatrol detections... you can give the fence a shake and watch a camera pan to you almost immediately).
From my prior comment: "Even a small nick in the insulation is supposed to change the impedance enough to create a detectable reflection."
This is what I was told by the person who saw the demo. I believe them, because it'd just be a matter of sending an impulse (or sweeping a tone) and looking at all of the spikes in the impulse response.
> 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.
It'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).
>"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...
Also 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.
Mark 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...)
I 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...
Kapton 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.
Kapton 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.
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