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Viability of conductive adhesive kit?

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Conundrum

Wed Jan 07 2015, 06:02AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Hi all.

It occurs to me that there is a market for conductive adhesive kits which do not in themselves contain any harmful solvents but with off-the-shelf additions such as Durite tyre repair cement or other RTV product will when mixed with the measured amounts in the kit have a well defined conductivity.

For a lot of applications such as EMC screening and DIY EL or LCD panels low conductivity does not matter, even 10K/cm2 which is feasible for ATO+tyre cement in the right proportions.

For even lower resistance ie connecting to 4 points on a superconducting pellet a good method I've found is to use an ultrasonic cleaner filled with a mild solvent and silver craft gilding foil.
This generates a range of particle sizes but the resistance is low enough to be useful once rinsed with acetone etc and then dried and mixed with a measured quantity of 30 minute Epoxy.

A good tip here is to heat treat the Epoxy once it starts to cure as the conductive properties improve possibly due to the surface oxides being removed by the reaction byproducts and settling of the silver particles.

Another interesting kit to sell would be a HTSC experimentation kit consisting of Y123/BSCCO, ATO and a few other compounds in an inert non aqueous binder which when mixed with the RTV will form a composite.
The 10nm ATO would form links between the HTSC particles (100um) and once dry would still exhibit the Meissner effect at LN2 temperatures as the ATO would conduct Cooper pairs due to the superconducting proximity effect.
Obviously not zero resistance but for certain applications such as sensors this does not matter.

Please advise.

I have 19.5g ATO here as well as assorted superconductive ceramics and specialist graphite so if anyone wants to try this and get back to me PM me.

Also see

note the use of iron and a magnet to form low resistance links.

Interesting that my dried out "useless" lead free solder paste might still have some use, seemed a shame to just chuck it.
I found a while back that Humbrol "Liquid Poly" also works well as a dispersant.

-Andre

Patrick

Wed Jan 07 2015, 06:42AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Are there other metals that can be made as ultra-thin leaf, not just gold or silver?

Conundrum

Wed Jan 07 2015, 06:52AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

I think you can get brass sheet as well.

Patrick

Wed Jan 07 2015, 07:13AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

brass... oooooooo what if zinc-copper could be super finely ground or ultra-thin 0.000001" thick, then maybe you could do 3d printing and such without silver....

(ANd or possibly bronze)

Bored Chemist

Wed Jan 07 2015, 11:18AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Two related questions strie me.
When you say "due to the surface oxides being removed by the reaction byproducts"
What oxidation products?
Silver is pretty stable in air.
And, on a related note, what would stop the very finely powdered brass/ bronze being severely oxidised to the point of not conducting?

Patrick

Wed Jan 07 2015, 04:27PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Bored Chemist wrote ...

And, on a related note, what would stop the very finely powdered brass/ bronze being severely oxidised to the point of not conducting?

Could the particles be suspended in the hardener and resin of an epoxy? so the air exposure is minimal? all of my silver epoxies say use in such and such a time... so maybe a milk expiration date isnt so crippling to this idea?

Shrad

Wed Jan 07 2015, 07:24PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

I'd use brazing compounds like the syringes sold as fast repair kits for copper pipe soldering

They contain silver particles and various other compounds, and may as well contain a proportion of copper or bronze, all in a small particle size

There is flux mixed in it in a greasy form but I guess ultrasonic cleaning in solvent mix could separate compounds

BigBad

Wed Jan 07 2015, 10:10PM

Registered Member #2529 Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600

What about graphite?

Conundrum

Thu Jan 08 2015, 07:26AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Yeah, graphite works.
I thought that a transparent conductor would be useful as this can be applied to both DIY solar cells such as the CuO and dye type and EL panels.
Also some people are now experimenting with OLED and the price of indium tin oxide glass is horrendous.

An interesting modification that avoids the troublesome gallium back contact is to use InxNa ie sodium as below 200C this is a solid.
Applying a very brief activation pulse to change it from amorphous to crystalline might work as the metal contact needs to have a low work function.

Shrad: I'll try this, thanks.
Graphite-ATO might be interesting also silver + ATO.
The aim here is to make a resistor not a good conductor as for many applications ie below 1mA resistance is less of an issue.

Shrad

Thu Jan 08 2015, 06:40PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

you might also try to pyrolyze cigarette filters... it is said to produce graphene...

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