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3M tape with anisotropic z-axis electrical conductivity

3m.com

61–70 of 146 posts

Re: 3M tape with anisotropic z-axis electrical conductivity

#61

Earlier quoted context omitted.

It was also quite a plausible hack. The faker, if indeed anything was faked, knew more than most. Enough to have done the thing for real.

It was completely implausible - the chip that was identified could not possibly carry enough processing ability to do anything useful as far as espionage goes, had no connectivity to networking, and there was never any evidence of communication from these devices to anything suspicious or unknown.

> processing power; networking

Could the device not simply get the host to do these things for it, by e.g. rootkit-ing the server’s BMC? A “hardware virus”, per se.

Re: 3M tape with anisotropic z-axis electrical conductivity

#62

Earlier quoted context omitted.

You could (in theory) put the tape over a circuit board and place components on tape and the circuit would function. It would not short circuit because it only conducts on the z-axis (up and down) not between things on the surface.

I don’t quite get how that’s useful.

It's useful in certain special circumstances where it's useful. It's probably not useful to you or most people.

It's just a very exotic and strange thing that does make some things possible which would otherwise be difficult or impractical some other way.

It can do essentially the same job as a zebra strip, with the following differendes:

Zebra strips are typically very thick blocks of silicone rubber. This is very thin tape.

Zebra are generally not adhesive. They're usually just a chunk of rubber that conducts electricity in two dimensions and insulates in one dimension, but the 3-part sandwich of pcb+zebra+part must be held in place mechanically (metal frames around lcd screens). This is double-sided adhesive tape.

Zebra conduct in two directions and insulate in one. They are useful in only one dimnsion. You can take a line of contacts and lay a zebra strip across them. The line can be curved or straight but it's sill essentially a single dimension which is along the line. IE the row of contacts could be say radiating lines and you could lay a zebra in a circle to cross tbose. What you can't have is a grid of dots or any other random arrangement of contacts, just a line. This tape however insulates in two dimensions and only conducts in only one dimension. It's like a tiny carpet of vertical conductors all insulated from each other. You can lay an inch square sheet of it right over a footprint of any random arrangement of contacts, and it conducts an exact image vertically up from each contact, but does not short between the contacts.

Some uses for that could be prototyping where you want to test components temporarily and conveniently without soldering. You just stick the components to the pcb with the magic tape and they actually work.

More likely uses are to connect things where soldering would be difficult or impossible. For instance connecting displays or ribbons to pcbs where the part may be glass with no metal to solder to, or delicate plastic film that would be destroyed by heat, etc. You can do that with zebra strips now, but this would allow packing in a whole lot more contacts into a smaller space. Or allow sticking components directly onto materials they can't be soldered to. Like sticking a chip directly onto the back of a glass display with no ribbon and no pcb.

Re: 3M tape with anisotropic z-axis electrical conductivity

#63
post #37

Earlier quoted context omitted.

Imagine a tiled surface, where the tiles are conductive but the grout is not. So you have islands of conductive material which don't connect to each other. If you shrink that very small, and make it flexible and sticky, it's useful: Suppose you have a glass LCD panel, like the kind used in clocks and watches. The traces are indium-tin-oxide (ITO), on the glass. This is fiendishly difficult to connect to, it doesn't t…

This is a great answer. I guess the "tiles" are so small that there's no way they could bridge even the tiniest IC packages?

The article has several pictures in which you can see that conductive grains in the tape are relatively sparse in the tape, such that any given grain isn't in contact with any other grains.

Re: 3M tape with anisotropic z-axis electrical conductivity

#64

A while back I invested in 3M because it's a company that makes so many amazing and industry leading products and I thought they'd do well. A couple years later and the stock is just lagging. I guess they're dragged down by their environmental lawsuits these days. As a human, I'm appalled at their environmental track record but as an engineer, wow they really do so many things so well.

I'm surprised they didn't do well during the pandemic. Their Aura masks were, like, weirdly better than every other mask I tried (at least in terms of comfort).

I feel like they just had an odd look to them, they are a KF94 design recertified as N95. But if you find them comfy when they make a good seal, that's what counts.

Some of the comfort may also be the breathability, Auras have a pretty low pressure diff between the inside and outside when in use. If you want that low pressure difference in a traditional N95 style, Indiana Face Mask makes some top notch high-filtration high-breathability N95s that are similar. Both they and the Auras usually test above 99.5% filtration, the Auras usually have a little bit of a petroleum smell but if it's bad enough that it makes the mask deeply unpleasant to wear, you probably have a fake (sometimes factory rejects get resold etc.).

Re: 3M tape with anisotropic z-axis electrical conductivity

#66
post #39

A while back I invested in 3M because it's a company that makes so many amazing and industry leading products and I thought they'd do well. A couple years later and the stock is just lagging. I guess they're dragged down by their environmental lawsuits these days. As a human, I'm appalled at their environmental track record but as an engineer, wow they really do so many things so well.

> A while back I invested in 3M because it's a company that makes so many amazing and industry leading products and I thought they'd do well. A couple years later and the stock is just lagging. The relevant question isn't whether they make great products, but whether their stock is undervalued. We in the tech world are used to "great products" -> "stock price always goes up", but in the "real world" there's no reason…

New great products, in blue-ocean markets, creating new revenue sources, aren’t enough? For companies the size of 3M that “do everything”, do market traders just price in a certain stable rate of predicted innovation leading to geometric revenue growth / monopoly positioning / etc?

Re: 3M tape with anisotropic z-axis electrical conductivity

#68

A while back I invested in 3M because it's a company that makes so many amazing and industry leading products and I thought they'd do well. A couple years later and the stock is just lagging. I guess they're dragged down by their environmental lawsuits these days. As a human, I'm appalled at their environmental track record but as an engineer, wow they really do so many things so well.

I'm surprised they didn't do well during the pandemic. Their Aura masks were, like, weirdly better than every other mask I tried (at least in terms of comfort).

Agreed, they're the most comfortable ones I found without an exhalation valve. Conveniently they also fold flat. Only downside is that they go behind the head instead of using ear loops.

Re: 3M tape with anisotropic z-axis electrical conductivity

#70

A while back I invested in 3M because it's a company that makes so many amazing and industry leading products and I thought they'd do well. A couple years later and the stock is just lagging. I guess they're dragged down by their environmental lawsuits these days. As a human, I'm appalled at their environmental track record but as an engineer, wow they really do so many things so well.

If you didn't already know, 3M shareholders can sign up for an annual holiday box. It costs money to order, but it's still much cheaper than buying the individual components (although if you don't need command hooks or post-it notes it might not be worth it for you)

Full disclosure: I am the proud owner of one share of MMM.

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