13 ms·

3M tape with anisotropic z-axis electrical conductivity

244 points by arsalanb 4y ago

csours 4y ago
Is there a less technical term for anisotropic? Polarized?
- icapybara 4y ago
  Anisotropic means “depends on direction”. This tape has conductivity that is different in one direction than the other two directions. This is unique because many materials have a conductivity that is the same regardless of the direction of current flow. Polarized is not the right word.
- Sporktacular 4y ago
  Directional, though anisotropic is a better description.
nomel 4y ago
For anyone looking for the interesting numbers: Insulation resistance: 3.4 x 1014 ohms/square Contact resistance: < 0.3 ohms Minimum gap: 0.4mm Minimum overlay area: 3.2mm^2 Direct link to datasheet: https://multimedia.3m.com/mws/media/66235O/3m-electrically-conductive-adhesive-transfer-tape-9703.pdf https://multimedia.3m.com/mws/media/66235O/3m-electrically-c...
- smegsicle 4y ago
  so the 3.4e14 is resistance along the tape, and .3 is vertically, right?
  - mensetmanusman 4y ago
    Yes, in plane (XY), it is many orders of magnitude more resistive than out of plane (Z-axis).
    - nuccy 4y ago
      Interesting, how "designed for EMI shielding" (as written on the product page) works then. The charges in the shield should be able to move not just in Z but also in X&Y to actually work as a Faraday cage.
      - nomel 4y ago
        > Z but also in X&Y to actually work as a Faraday cage. The x-y could be done by the contiguous ground above and below the tape. For example a can/shield stuck onto a ground region of a PCB, with signal lines going up nearby. I imagine this is mostly used with flex PCBs.
- crmd 4y ago
  Thanks. This is exactly what I was looking for, and it was annoying this wasn’t in the specification or details section.
- db48x 4y ago
  I think you mean 3×10¹⁴ ohms/square.
- kurthr 4y ago
  What people should also know is that every single display, and that includes every single cell phone touch screen has ACF (Anisotropic Conductive Film) in them. They aren't the same contact adhesive as this 3M film, and some are moderately expensive (e.g. >$0.25/inch @1mm width) for those displays, which is at least comparable (>10%) to the display ICs attached to them. Why is so much ACF used? Because it is the most cost effective and compact way to connect dissimilar high density connections from one substrate to another. Displays typically require thousands of connections so you're looking at linear densities of 1 contact per mil (~25um) with resistances measured in ohms (for less than 0.01mmsq). The reason that IC packages (internally wire bonded or electroplated CSP) don't use ACF is a combination of cost, self alignment (solder pulls it into place), and much lower resistance. The way that almost all of these ACFs are made is embedding conductive beads (often spherical of controlled diameter) which can compress when the adhesive is pressed/bonded to the two substrates. If the aerial density of the beads is right, you'll only get a few beads in contact and none will short any neighboring contacts. For displays the ACF material is typically a ~25um thick B-stage epoxy, which is tacked down and then "snaps" when heated and compressed permanently pulling together the two contact regions and compressing ~10um gold coated polystyrene balls between gold "fingers" on each glass/PCB/COF/COP side after the epoxy flows. 3M tried to get into these higher end ACFs, but now it's mostly Japanese and Korean suppliers.
- Sporktacular 4y ago
  To clarify, those figure are after bonding right? I understand that means it must be heated and compressed between conductors to reach those values.
mensetmanusman 4y ago
This is sometimes used to connect rigid touch panel electrodes (on glass) to flex cables, bypasses having to do lots of soldering…
- Brian_K_White 4y ago
  Seems like it would be a good replacement for zebra strips. Not in existing vintage devices that need multi-mm of height but just in principle like if you were making something new.
loxias 4y ago
The prowess of materials science in companies like 3M and Dupont never ceases to amaze me. Just when I think I've seen it all with fiberglass tape and kapton tape...
- markdown 4y ago
  Their "prowess" saw DuPont give cigarettes laced with new toxic chemicals they made to their employees to test the chemicals effects. Every human on earth has Dupont chemicals in their blood that will never go away, but accumulate over the course of our lives. These are "forever chemicals" that never break down. When you die you pass them on. They are in the animals you eat, in the beverages and water you drink, they are in the vegetables you eat. Your descendants a millennium from now will be eating them still, plus all the new ones produced between now and then. This is the result of American capitalism and the worlds most corrupt banana republic legislature where bribery is so bad they made it legal. Those absolutely evil bottom dwellers at Dupont you admire so much produce hundreds of toxic chemicals, and your bribed government allows them to produce and market these chemicals and spread them around the world without consequence. Fuck Dupont and Fuck 3M. They are poisoning the planet. https://www.netflix.com/title/81192027 https://www.netflix.com/title/81192027
  - deleted 4y ago
    [deleted]
  - dxuh 4y ago
    That Netflix link is not available everywhere and also quite time-consuming to review. Obviously it is also a dramatic piece rather than a (semi-)scientific. I had a brief look at the PFAS wikipedia page (https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_substances https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_subst...), which is what that Netflix movie seems to be about, but it's also quite wordy and the claims you make can not be found on there as-is. Maybe you want to consider adding a better source.
    - markdown 4y ago
      https://www.popsci.com/story/environment/dark-waters-chemicals-pfas/ https://www.popsci.com/story/environment/dark-waters-chemica... Basically, the US government allows companies to sell new chemicals they invent, completely unregulated. You could make a toxin today that kills everyone who touches it 10 years after they ingest it, and you would be free to market and sell this product. The chemical is presumed safe until evidence to the contrary comes to the knowledge of the govt. That's how Dupont poisoned people all over the world. They sold unregulated chemicals they invented that nobody but them knew about. One report by the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES) found PFAS in the blood of 97% of Americans... The number of new PFAS chemicals appear to be increasing, and exposure is difficult to assess. - https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm
AceJohnny2 4y ago
What's Z-axis on this tape? is it thickness?
- akubera 4y ago
  It's conductive only in the z-axis. So you can, for example, tape components to your circuitboard instead of having to solder tiny pieces.
  - chrisseaton 4y ago
    I think they were asking… what is the z-axis? What’s the canonical co—ordinate system for tape? You just repeated that it’s conductive in the z-axis.
    - akubera 4y ago
      Yes, z-axis is the direction of the tape's "thickness" so electricity passes only from the thing stuck to the top to the thing stuck to the bottom (directly through the tape) without shorting the rest of the contacts. I misread the question to be "what makes this 'z-axis' tape" rather than "which axis is the z-axis of the tape".
- jbay808 4y ago
  Yes, the z axis is the thickness direction.
- deleted 4y ago
  [deleted]
raldi 4y ago
What does that mean?
- db48x 4y ago
  “Isotropic” means that something is the same in all directions, and “anisotropic” means that it _isn’t_ the same in all directions. In this case, the tape conducts electricity between its top and bottom surfaces, but not along its length.
  - an1sotropy 4y ago
    well said.
- teruakohatu 4y ago
  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.
  - heavyset_go 4y ago
    I take it the tape would go in the middle between the circuit board and components?
    - Brian_K_White 4y ago
      "I take it the tape would go in the middle between the circuit board and components?" Let me see... "place the tape on a circuit board and place components on the tape"
      - heavyset_go 4y ago
        Thanks, without your constructive comment I would've never known that I was asking a dumb question.
  - 4y ago
hedgehog 4y ago
The first place I saw this stuff was a presentation by one of the people behind Chibitronics. Along with copper tape really useful for building up circuits on paper. Not sure if they still use it in any of the products but still pretty cool: https://chibitronics.com https://chibitronics.com
01100011 4y ago
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.
- deleted 4y ago
  [deleted]
- systemvoltage 4y ago
  3M is an awesome company. I've worked with them to produce custom adhesives for us ($MM orders). Their products have exceptional quality, reliability and performance. What you see in a datasheet is what you're going to get (or better). 3M's consumer products (Scotch, etc.) are also excellent. Anytime you use 3M products, you don't need to worry. I like that consistency and it brings peace to the mind. I'll pay more for it. Japanese equivalent is Nitto: https://www.nitto.com/us/en/products/ https://www.nitto.com/us/en/products/
  - InitialLastName 4y ago
    Not just that, but (at least when last I needed this specific service) they had a great phone support system where you could call up and say "I need an adhesive to connect $A to $B and have these curing properties and this strength" and someone would go through their database and make a list for you. Most companies with such a huge array of subtly different products are nowhere near so clear.
  - mensetmanusman 4y ago
    One cool thing now is that 3M releases finite element data packages for adhesive tapes, digital prototyping! https://www.3m.com/3M/en_US/bonding-and-assembly-us/resources/full-story/~/fea-data-for-3m-psas/?storyid=ccd4a185-5e5b-4439-83ec-3ede3443231e https://www.3m.com/3M/en_US/bonding-and-assembly-us/resource...
  - steve_adams_86 4y ago
dan000892 4y ago
This stuff is rad. I took a class on hardware implants with Joe Fitz a couple years back—on the heels of that wholly unsubstantiated Bloomberg article about China embedding rice grain-sized hardware implants into Supermicro motherboards that magically found their way only to select F100s and gov’t agencies—where we made a PCB to interface an ATtiny85 to an unpopulated UART header on some IoT device but instead of soldering it down we just taped it with this. (The UART provided a root shell and enough power to “boot” the ATtiny which simply waited a few seconds and then ran some commands to initiate a reverse shell to a server under our control every time the device was powered on. Thanks to this tape and the device’s tool-less case (and convenient unpopulated header with space around it), it was enlightening how trivially easy it’d be to develop and deploy such an implant to an operating device (with the caveat that I wouldn’t consider the connection robust enough to survive transport). It’s also useful to connect SMD EEPROMs to unpopulated/desoldered pads for testing without installing a socket.
- mardifoufs 4y ago
  Yep! But it sadly cannot replace soldering for denser pinout layouts, unless a lot of pressure is applied. Someone tried though; https://tomverbeure.github.io/2019/11/21/Z-tape.html https://tomverbeure.github.io/2019/11/21/Z-tape.html (A bit off topic but that Bloomberg story is still such a mystery to me. It went into quite a bit of details and claimed it had tons of sources, so even if it was a completely false story whoever fabricated it must have put insane amounts of efforts/identity fraud into the set up)
  - timschmidt 4y ago
    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.
    - djrogers 4y ago
      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.
deleted 4y ago
[deleted]
n4bz0r 4y ago
Could this be used for CPU (or some other truckload-of-pins chip) "reballing"? Does it do well under a bolted-on radiator / pressure plate? For instance, many old Playstation 3 systems go faulty because of the poor quality solder on the CPU/GPU that tends to crack over time. Being a normie, it's really hard to fix something like that at home. But this tape seems like it could save the day.
- adfhadghnadgnag 4y ago
  There's no way you could have good enough signal integrity. The frequency is high and there's no clever signal processing. I have never tried it but it seems implausible.
- magicalhippo 4y ago
  > Could this be used for CPU (or some other truckload-of-pins chip) "reballing"? The datasheet[1] says the minimum gap between conductors is 0.4mm, so based on that it should work for 0.5/0.65mm BGA. Also would clearly affect the speed you can run things at due to introducing parasitics. But would certainly be fun to try. [1]: https://multimedia.3m.com/mws/media/66235O/3m-electrically-conductive-adhesive-transfer-tape-9703.pdf https://multimedia.3m.com/mws/media/66235O/3m-electrically-c...
  - teraflop 4y ago
    Getting the chip lined up accurately enough might be a bit trickier. With soldering, you can normally rely on the solder's surface tension to pull the pads into alignment.
itsyaboi 4y ago
Oof, a roll of this stuff is ~$180
bpye 4y ago
Ben Krasnow used this for his DSKY replica [0] - its a very interesting product. [0] - https://youtu.be/Z2o_Sp2-aBo https://youtu.be/Z2o_Sp2-aBo
Animats 4y ago
Neat. Elastomeric materials like that are widely used, made from alternating insulating and conductive layers. They need external compression. An adhesive tape is a clever variation.
Rebelgecko 4y ago
It's been pretty entertaining to watch the stocks of this stuff on Amazon dwindle minute by minute
mNovak 4y ago
Years ago I had the idea to use this tape to make solder-free PCB kits to teach electric circuits (the tape would connect the chip pins to the board, without shorting sideways). I bought a roll, and printed some boards for LEDs and 555 timers and such. Unfortunately it didn't make reliable contact for the chip pins unless you were constantly pushing down on it. As I recall the datasheet states as much. That seems like a solvable material science problem, but alas perhaps not valuable enough.
robomartin 4y ago
I went to look at this expecting it to also have excellent thermal conductivity (due to the low resistance z-axis conductivity through silver particles). To my surprise, it does not. The published range is 0.16-0.20 W/mK, which is pretty much what you get for most tape products. We use specialized thermally conductive tapes in a range >= 1 W/mK. I am always looking for interesting developments in this domain.
alkonaut 4y ago
Would be extremely useful to get an explanation of what 3M means is the "Z-axis" of the tape. Along the tape plane? Across the tape plane? Through the tape plane? I can see uses for all, but how you'd apply it would certainly differ if depending on which one is Z....
- arsalanb 4y ago
  z-axis is the thickness of the tape
ghoul2 4y ago
This stuff confused the hell out of me as a 6-yr old electronics hobbyist (read unskilled-tear-downer). Took apart a non-functioning lcd calculator. Everything looked normal, except the lcd display itself was just pressed onto a rubbery tape like thing which seemed to be stuck to a line of pads in the pcb. I expected a flex cable connecting the lcd to the PCB but couldn't find one. I 'knew' rubber was an insulator, so no matter what that rubbery thing was (I guessed it was simply a spacer) it wasn't the connection between the two. Didn't learn about the existence of z-tape for another decade or so and immediately the light bulb in my brain flashed, solving a childhood mystery.
- rob_c 4y ago
  The clue would also be the clear doping of the conductive layer...
- myself248 4y ago
  It's a shame your 6yo self didn't have a microscope around, or even a decent magnifying glass! Zebra-strip is incredibly distinct once you're viewing it up close, and I bet its function would've immediately clicked upon seeing the structure.
  - ghoul2 4y ago
    Oh, I had a cheap magnifying glass; And I had access to a "Community Science Center" where they would have let me use a high-school-class microscope if I begged enough* . The problem was it didn't even occur to me to take that tiny rubbery strip that seriously. True shame really - by that time I had taken apart enough LCD calculators for there to be nothing surprising in any of them. This was the first surprise, in a while. I really should have focused on figuring it out. Just never occurred to me that the 10mmx1mmx1mm thingy was such an awesome thing. *for free too; It was my favorite Saturday hangout spot - watching lab demonstrations, animal dissections etc, playing with the ever-changing interactive science demos).
    - myself248 4y ago
      Oof. Yeah. I have my own "I could've done something amazing if I'd just realized I needed to push on that thing that didn't look like a button" moment as a kid. A little nudge of guidance would've gone a long way.
whalesalad 4y ago
If y'all have never been on McMaster-Carr, you are in for a treat: https://www.mcmaster.com https://www.mcmaster.com All kinds of stuff like this can be explored with a pretty decent UI.
natch 4y ago
Unless I'm misreading this, it's $19.78 / yard for 4" wide size at digikey. If the link doesn't work (lots of tokens in there) try searching for "9703 3M tape conductive" as a starting point. https://www.digikey.com/en/products/detail/3m/9703-4-X36YD/6820572?s=N4IgjCBcoOw1oDGUBmBDANgZwKYBoQB7KAbRBjAA4AWANhAF0CAHAFyhAGVWAnASwB2AcxABfAmGrxoIZJHTZ8RUiGoBmAAz0mINh279hYiTHoy5C3AWKQyAJgCsDrdUYt2kLr0Ejx4OAiyqJhWyrYgamAadhoAnG66Hl6GvhKxaoEWIUo29hrULgl6ngY%2BxqrpmcGK1ipq6g60GkVJpUZ%2BtLHx5tWhuRGUsZTDLfre7QQwGs098tm14WrDDo6jJeOp4BowdlVzNWFkBQ6uOsXJZX5gQ91IvTkqzWetG%2BUAtBCzlg-h14x%2Bb1cX3mhxAQ0i-wIbwce2%2BCzItAgDFEfl24ViUwyyKAA https://www.digikey.com/en/products/detail/3m/9703-4-X36YD/6...

244 points by arsalanb 4y ago

csours 4y ago

Is there a less technical term for anisotropic? Polarized?

icapybara 4y ago
Anisotropic means “depends on direction”. This tape has conductivity that is different in one direction than the other two directions. This is unique because many materials have a conductivity that is the same regardless of the direction of current flow. Polarized is not the right word.
Sporktacular 4y ago
Directional, though anisotropic is a better description.

nomel 4y ago

For anyone looking for the interesting numbers: Insulation resistance: 3.4 x 1014 ohms/square Contact resistance: < 0.3 ohms Minimum gap: 0.4mm Minimum overlay area: 3.2mm^2 Direct link to datasheet: https://multimedia.3m.com/mws/media/66235O/3m-electrically-conductive-adhesive-transfer-tape-9703.pdf https://multimedia.3m.com/mws/media/66235O/3m-electrically-c...

smegsicle 4y ago
so the 3.4e14 is resistance along the tape, and .3 is vertically, right?
- mensetmanusman 4y ago
  Yes, in plane (XY), it is many orders of magnitude more resistive than out of plane (Z-axis).
  - nuccy 4y ago
    Interesting, how "designed for EMI shielding" (as written on the product page) works then. The charges in the shield should be able to move not just in Z but also in X&Y to actually work as a Faraday cage.
    - nomel 4y ago
      > Z but also in X&Y to actually work as a Faraday cage. The x-y could be done by the contiguous ground above and below the tape. For example a can/shield stuck onto a ground region of a PCB, with signal lines going up nearby. I imagine this is mostly used with flex PCBs.
crmd 4y ago
Thanks. This is exactly what I was looking for, and it was annoying this wasn’t in the specification or details section.
db48x 4y ago
I think you mean 3×10¹⁴ ohms/square.
kurthr 4y ago
What people should also know is that every single display, and that includes every single cell phone touch screen has ACF (Anisotropic Conductive Film) in them. They aren't the same contact adhesive as this 3M film, and some are moderately expensive (e.g. >$0.25/inch @1mm width) for those displays, which is at least comparable (>10%) to the display ICs attached to them. Why is so much ACF used? Because it is the most cost effective and compact way to connect dissimilar high density connections from one substrate to another. Displays typically require thousands of connections so you're looking at linear densities of 1 contact per mil (~25um) with resistances measured in ohms (for less than 0.01mmsq). The reason that IC packages (internally wire bonded or electroplated CSP) don't use ACF is a combination of cost, self alignment (solder pulls it into place), and much lower resistance. The way that almost all of these ACFs are made is embedding conductive beads (often spherical of controlled diameter) which can compress when the adhesive is pressed/bonded to the two substrates. If the aerial density of the beads is right, you'll only get a few beads in contact and none will short any neighboring contacts. For displays the ACF material is typically a ~25um thick B-stage epoxy, which is tacked down and then "snaps" when heated and compressed permanently pulling together the two contact regions and compressing ~10um gold coated polystyrene balls between gold "fingers" on each glass/PCB/COF/COP side after the epoxy flows. 3M tried to get into these higher end ACFs, but now it's mostly Japanese and Korean suppliers.
Sporktacular 4y ago
To clarify, those figure are after bonding right? I understand that means it must be heated and compressed between conductors to reach those values.

mensetmanusman 4y ago

This is sometimes used to connect rigid touch panel electrodes (on glass) to flex cables, bypasses having to do lots of soldering…

Brian_K_White 4y ago
Seems like it would be a good replacement for zebra strips. Not in existing vintage devices that need multi-mm of height but just in principle like if you were making something new.

loxias 4y ago

The prowess of materials science in companies like 3M and Dupont never ceases to amaze me. Just when I think I've seen it all with fiberglass tape and kapton tape...

markdown 4y ago
Their "prowess" saw DuPont give cigarettes laced with new toxic chemicals they made to their employees to test the chemicals effects. Every human on earth has Dupont chemicals in their blood that will never go away, but accumulate over the course of our lives. These are "forever chemicals" that never break down. When you die you pass them on. They are in the animals you eat, in the beverages and water you drink, they are in the vegetables you eat. Your descendants a millennium from now will be eating them still, plus all the new ones produced between now and then. This is the result of American capitalism and the worlds most corrupt banana republic legislature where bribery is so bad they made it legal. Those absolutely evil bottom dwellers at Dupont you admire so much produce hundreds of toxic chemicals, and your bribed government allows them to produce and market these chemicals and spread them around the world without consequence. Fuck Dupont and Fuck 3M. They are poisoning the planet. https://www.netflix.com/title/81192027 https://www.netflix.com/title/81192027
- deleted 4y ago
  [deleted]
- dxuh 4y ago
  That Netflix link is not available everywhere and also quite time-consuming to review. Obviously it is also a dramatic piece rather than a (semi-)scientific. I had a brief look at the PFAS wikipedia page (https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_substances https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_subst...), which is what that Netflix movie seems to be about, but it's also quite wordy and the claims you make can not be found on there as-is. Maybe you want to consider adding a better source.
  - markdown 4y ago
    https://www.popsci.com/story/environment/dark-waters-chemicals-pfas/ https://www.popsci.com/story/environment/dark-waters-chemica... Basically, the US government allows companies to sell new chemicals they invent, completely unregulated. You could make a toxin today that kills everyone who touches it 10 years after they ingest it, and you would be free to market and sell this product. The chemical is presumed safe until evidence to the contrary comes to the knowledge of the govt. That's how Dupont poisoned people all over the world. They sold unregulated chemicals they invented that nobody but them knew about. One report by the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES) found PFAS in the blood of 97% of Americans... The number of new PFAS chemicals appear to be increasing, and exposure is difficult to assess. - https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm

AceJohnny2 4y ago

What's Z-axis on this tape? is it thickness?

akubera 4y ago
It's conductive only in the z-axis. So you can, for example, tape components to your circuitboard instead of having to solder tiny pieces.
- chrisseaton 4y ago
  I think they were asking… what is the z-axis? What’s the canonical co—ordinate system for tape? You just repeated that it’s conductive in the z-axis.
  - akubera 4y ago
    Yes, z-axis is the direction of the tape's "thickness" so electricity passes only from the thing stuck to the top to the thing stuck to the bottom (directly through the tape) without shorting the rest of the contacts. I misread the question to be "what makes this 'z-axis' tape" rather than "which axis is the z-axis of the tape".
jbay808 4y ago
Yes, the z axis is the thickness direction.
deleted 4y ago
[deleted]

raldi 4y ago

What does that mean?

db48x 4y ago
“Isotropic” means that something is the same in all directions, and “anisotropic” means that it _isn’t_ the same in all directions. In this case, the tape conducts electricity between its top and bottom surfaces, but not along its length.
- an1sotropy 4y ago
  well said.
teruakohatu 4y ago
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.
- heavyset_go 4y ago
  I take it the tape would go in the middle between the circuit board and components?
  - Brian_K_White 4y ago
    "I take it the tape would go in the middle between the circuit board and components?" Let me see... "place the tape on a circuit board and place components on the tape"
    - heavyset_go 4y ago
      Thanks, without your constructive comment I would've never known that I was asking a dumb question.
- 4y ago

hedgehog 4y ago

The first place I saw this stuff was a presentation by one of the people behind Chibitronics. Along with copper tape really useful for building up circuits on paper. Not sure if they still use it in any of the products but still pretty cool: https://chibitronics.com https://chibitronics.com

01100011 4y ago

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.

deleted 4y ago
[deleted]
systemvoltage 4y ago
3M is an awesome company. I've worked with them to produce custom adhesives for us ($MM orders). Their products have exceptional quality, reliability and performance. What you see in a datasheet is what you're going to get (or better). 3M's consumer products (Scotch, etc.) are also excellent. Anytime you use 3M products, you don't need to worry. I like that consistency and it brings peace to the mind. I'll pay more for it. Japanese equivalent is Nitto: https://www.nitto.com/us/en/products/ https://www.nitto.com/us/en/products/
- InitialLastName 4y ago
  Not just that, but (at least when last I needed this specific service) they had a great phone support system where you could call up and say "I need an adhesive to connect $A to $B and have these curing properties and this strength" and someone would go through their database and make a list for you. Most companies with such a huge array of subtly different products are nowhere near so clear.
- mensetmanusman 4y ago
  One cool thing now is that 3M releases finite element data packages for adhesive tapes, digital prototyping! https://www.3m.com/3M/en_US/bonding-and-assembly-us/resources/full-story/~/fea-data-for-3m-psas/?storyid=ccd4a185-5e5b-4439-83ec-3ede3443231e https://www.3m.com/3M/en_US/bonding-and-assembly-us/resource...
- steve_adams_86 4y ago

dan000892 4y ago

This stuff is rad. I took a class on hardware implants with Joe Fitz a couple years back—on the heels of that wholly unsubstantiated Bloomberg article about China embedding rice grain-sized hardware implants into Supermicro motherboards that magically found their way only to select F100s and gov’t agencies—where we made a PCB to interface an ATtiny85 to an unpopulated UART header on some IoT device but instead of soldering it down we just taped it with this. (The UART provided a root shell and enough power to “boot” the ATtiny which simply waited a few seconds and then ran some commands to initiate a reverse shell to a server under our control every time the device was powered on. Thanks to this tape and the device’s tool-less case (and convenient unpopulated header with space around it), it was enlightening how trivially easy it’d be to develop and deploy such an implant to an operating device (with the caveat that I wouldn’t consider the connection robust enough to survive transport). It’s also useful to connect SMD EEPROMs to unpopulated/desoldered pads for testing without installing a socket.

mardifoufs 4y ago
Yep! But it sadly cannot replace soldering for denser pinout layouts, unless a lot of pressure is applied. Someone tried though; https://tomverbeure.github.io/2019/11/21/Z-tape.html https://tomverbeure.github.io/2019/11/21/Z-tape.html (A bit off topic but that Bloomberg story is still such a mystery to me. It went into quite a bit of details and claimed it had tons of sources, so even if it was a completely false story whoever fabricated it must have put insane amounts of efforts/identity fraud into the set up)
- timschmidt 4y ago
  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.
  - djrogers 4y ago
    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.

deleted 4y ago

[deleted]

n4bz0r 4y ago

Could this be used for CPU (or some other truckload-of-pins chip) "reballing"? Does it do well under a bolted-on radiator / pressure plate? For instance, many old Playstation 3 systems go faulty because of the poor quality solder on the CPU/GPU that tends to crack over time. Being a normie, it's really hard to fix something like that at home. But this tape seems like it could save the day.

adfhadghnadgnag 4y ago
There's no way you could have good enough signal integrity. The frequency is high and there's no clever signal processing. I have never tried it but it seems implausible.
magicalhippo 4y ago
> Could this be used for CPU (or some other truckload-of-pins chip) "reballing"? The datasheet[1] says the minimum gap between conductors is 0.4mm, so based on that it should work for 0.5/0.65mm BGA. Also would clearly affect the speed you can run things at due to introducing parasitics. But would certainly be fun to try. [1]: https://multimedia.3m.com/mws/media/66235O/3m-electrically-conductive-adhesive-transfer-tape-9703.pdf https://multimedia.3m.com/mws/media/66235O/3m-electrically-c...
- teraflop 4y ago
  Getting the chip lined up accurately enough might be a bit trickier. With soldering, you can normally rely on the solder's surface tension to pull the pads into alignment.

itsyaboi 4y ago

Oof, a roll of this stuff is ~$180

bpye 4y ago

Ben Krasnow used this for his DSKY replica [0] - its a very interesting product. [0] - https://youtu.be/Z2o_Sp2-aBo https://youtu.be/Z2o_Sp2-aBo

Animats 4y ago

Neat. Elastomeric materials like that are widely used, made from alternating insulating and conductive layers. They need external compression. An adhesive tape is a clever variation.

Rebelgecko 4y ago

It's been pretty entertaining to watch the stocks of this stuff on Amazon dwindle minute by minute

mNovak 4y ago

Years ago I had the idea to use this tape to make solder-free PCB kits to teach electric circuits (the tape would connect the chip pins to the board, without shorting sideways). I bought a roll, and printed some boards for LEDs and 555 timers and such. Unfortunately it didn't make reliable contact for the chip pins unless you were constantly pushing down on it. As I recall the datasheet states as much. That seems like a solvable material science problem, but alas perhaps not valuable enough.

robomartin 4y ago

I went to look at this expecting it to also have excellent thermal conductivity (due to the low resistance z-axis conductivity through silver particles). To my surprise, it does not. The published range is 0.16-0.20 W/mK, which is pretty much what you get for most tape products. We use specialized thermally conductive tapes in a range >= 1 W/mK. I am always looking for interesting developments in this domain.

alkonaut 4y ago

Would be extremely useful to get an explanation of what 3M means is the "Z-axis" of the tape. Along the tape plane? Across the tape plane? Through the tape plane? I can see uses for all, but how you'd apply it would certainly differ if depending on which one is Z....

arsalanb 4y ago
z-axis is the thickness of the tape

ghoul2 4y ago

This stuff confused the hell out of me as a 6-yr old electronics hobbyist (read unskilled-tear-downer). Took apart a non-functioning lcd calculator. Everything looked normal, except the lcd display itself was just pressed onto a rubbery tape like thing which seemed to be stuck to a line of pads in the pcb. I expected a flex cable connecting the lcd to the PCB but couldn't find one. I 'knew' rubber was an insulator, so no matter what that rubbery thing was (I guessed it was simply a spacer) it wasn't the connection between the two. Didn't learn about the existence of z-tape for another decade or so and immediately the light bulb in my brain flashed, solving a childhood mystery.

rob_c 4y ago
The clue would also be the clear doping of the conductive layer...
myself248 4y ago
It's a shame your 6yo self didn't have a microscope around, or even a decent magnifying glass! Zebra-strip is incredibly distinct once you're viewing it up close, and I bet its function would've immediately clicked upon seeing the structure.
- ghoul2 4y ago
  Oh, I had a cheap magnifying glass; And I had access to a "Community Science Center" where they would have let me use a high-school-class microscope if I begged enough* . The problem was it didn't even occur to me to take that tiny rubbery strip that seriously. True shame really - by that time I had taken apart enough LCD calculators for there to be nothing surprising in any of them. This was the first surprise, in a while. I really should have focused on figuring it out. Just never occurred to me that the 10mmx1mmx1mm thingy was such an awesome thing. *for free too; It was my favorite Saturday hangout spot - watching lab demonstrations, animal dissections etc, playing with the ever-changing interactive science demos).
  - myself248 4y ago
    Oof. Yeah. I have my own "I could've done something amazing if I'd just realized I needed to push on that thing that didn't look like a button" moment as a kid. A little nudge of guidance would've gone a long way.

whalesalad 4y ago

If y'all have never been on McMaster-Carr, you are in for a treat: https://www.mcmaster.com https://www.mcmaster.com All kinds of stuff like this can be explored with a pretty decent UI.

natch 4y ago

Unless I'm misreading this, it's $19.78 / yard for 4" wide size at digikey. If the link doesn't work (lots of tokens in there) try searching for "9703 3M tape conductive" as a starting point. https://www.digikey.com/en/products/detail/3m/9703-4-X36YD/6820572?s=N4IgjCBcoOw1oDGUBmBDANgZwKYBoQB7KAbRBjAA4AWANhAF0CAHAFyhAGVWAnASwB2AcxABfAmGrxoIZJHTZ8RUiGoBmAAz0mINh279hYiTHoy5C3AWKQyAJgCsDrdUYt2kLr0Ejx4OAiyqJhWyrYgamAadhoAnG66Hl6GvhKxaoEWIUo29hrULgl6ngY%2BxqrpmcGK1ipq6g60GkVJpUZ%2BtLHx5tWhuRGUsZTDLfre7QQwGs098tm14WrDDo6jJeOp4BowdlVzNWFkBQ6uOsXJZX5gQ91IvTkqzWetG%2BUAtBCzlg-h14x%2Bb1cX3mhxAQ0i-wIbwce2%2BCzItAgDFEfl24ViUwyyKAA https://www.digikey.com/en/products/detail/3m/9703-4-X36YD/6...