Electrically conductive adhesive, suggestions wanted.

[timwatson]

OK so I have a few projects of late that could benefit from some electrically conductive adhesive.
I wanted to pick the collective brains of you all and see what you knew about.

There are some "requirements":
1. High heat rigidity - there is a better word other than rigidity, but it escaping me at the moment (meaning it won't melt or turn to goo if it gets hot).
2. High strength
3. Can be semi flexible
4. Insert your own here for theory crafting purposes

I did just purchase some "Arctic Silver Thermal adhesive".
http://www.quadrocopter.com/product.asp?itemid=318
It isn't conductive but meets or exceeds the other "requirements". It's very odd it's not conductive.

Does such an adhesive exist?

[peteski]

Tim,
how much heat are you talking about?  100, 300, 700 degrees F?

As far as the adhesive you found, judging by its name, it is supposedly thermally (not electrically) conductive.  Those are apples and oranges.
You need electrically conductive adhesive.

Do a google search for electrically conductive adhesive
Some that I have used in the past are
http://www.mgchemicals.com/products/adhesives/electrically-conductive/silver-conductive-epoxy-8331/
http://www.mscdirect.com/product/details/05900915?src=pla&008=-99&pcrid=15557577904&007=Search&006=15557577904&005=21882504424&004=4409695744&002=2167139&mkwid=sJXegN7a0|dc&cid=PLA-Google-PLA+-+Test_sJXegN7a0_PLA__15557577904_c_S&026=-99&025=c&item=05900915

Here is a webpage which might be useful to you http://www.henkel.com/electrically-conductive-adhesives-27427.htm

You might also look into conductive paint (used as adhesive). It depends what you need this for.
I've used http://www.chemtronics.com/p-693-circuitworks-conductive-pen.aspx

As you can see, all these are silver-based and rather pricey. But it is the silver is what makes them conductive.

[LV LOU]

http://www.ebay.com/itm/Silver-Epoxy-Electrically-Conductive-Heat-Cure-2-part-10-grams-/151262913167?pt=LH_DefaultDomain_0&hash=item2337f8e28f

[mmagliaro]

I don't know what your high heat requirement exactly is, but I swear by Nickel Print.

http://www.mgchemicals.com/products/prototyping-and-circuit-repair/circuit-repair/nickel-print-840/

It is a pretty strong glue, and it has excellent conductivity.  In fact, I have been using it to repair "dead"
Kato Mikado drivers and it works great.   All the cheaper carbon-based conductive glues are pretty much junk.
The silver ones are expensive, although I'm sure they work great.

This stuff seems to be a happy medium of strength, conductivity, and cost.

[mecgp7]

Not to hijack the thread, but would this work instead of solder for track joints?

[glakedylan]

IMO...track joints and wire attachments need soldering as to how wear and tear takes its toll on such.

now, after stating this, I have an idea--not wanting to sidetrack or hijack this thread myself--I have
not insulated frog PECO crossings that I picked up by mistake. I need the electrofrog kind.

would such work by painting onto the plastic frogs to make them current conductive?

I realize it would have to be reapplied again and again with usage...but I am wondering?

thanks

Gary

[mmagliaro]

In answer to the questions about coating plastic frogs or using on track joints, I say a resounding, "No."
This is asking for trouble.  On a track joint, if you use a rail joiner, you might get away with it but over time I would
expect the expansion and contraction at the joint to break the glue bond and result in flakey contact.
I also don't think even a good coating of this stuff (I'm talking about Nickel Print now) would carry enough current.
Remember, for a contact inside an engine, the coating only has to carry the current for one engine.
On the track, it might have to carry 3 amps, 5 amps, or whatever your particular limits are for multiple engines with possibly
lighted cars.

As for the plastic frog, I would expect it to help for a while, and I would expect it to chip off and become a nuisance.
If you can't replace the plastic-frogged turnouts, I guess it's worth a shot, but it's not a metal frog.

[timwatson]

Getting back on track ... (yup I just did that). 

You might also look into conductive paint (used as adhesive). It depends what you need this for.
I've used http://www.chemtronics.com/p-693-circuitworks-conductive-pen.aspx

As you can see, all these are silver-based and rather pricey. But it is the silver is what makes them conductive.

Hey Pete I figured you had an idea on something to use. I saw this very pen in Radio Shack and debated on using it. To be honest I'd be surprised if I need anything beyond 300 F but I'm not sure. I'm going to use it on a motor brush. More on that later. How strong do you think the pen liquid is? Is it more like paint?

http://www.mgchemicals.com/products/prototyping-and-circuit-repair/circuit-repair/nickel-print-840/
This stuff seems to be a happy medium of strength, conductivity, and cost.

Thanks Max, you gave me what I needed - first hand account of use. I'm thinking I will try the nickel first before moving onto silver. The biggest factor will be to get it to be durable under heat. This looks like it might be the stuff. Man Amazon makes ordering this stuff easy.

Gary this isn't for any wire attachments (or plastic frogs). I use silver bearing solder for track mostly - unless it's a quick solder job and then its maybe some rosin core.

Thanks Lou for the reply. I think I'm going to try Max's suggestion. More on what I've been up to later.

[carlso]

Good thread guys and it is something that I was thinking about trying to find. Here is what I am doing:

I have a set of KATO GS-4 tender trucks that I want to add pickup wires to. The little tabs are rather short and have plastic up one side of the tab. I am afraid that soldering would melt the plastic and cause the wipers to be loose in the truck sideframe. What type of the afore mentioned "glues" would work best? BTW, these are not being used on a GS-4 but rather another "project".

Thanks for any comments.

Carl

[mmagliaro]

Nickel Print would probably work for that.  But to be honest, I would still go with a drop of paste flux, and some good
soldering technique.  When soldering fine wires to tender truck tabs, there is always a danger of melting the truck frames.
You need to be in and out in a fraction of a second.  File the tip of the tab super clean with a file.  Tin the wire with solder beforehand.
Put a drop of flux on the truck tab and tin it.  THEN you should be able to make that joint in the blink of an eye and not melt the frame.

The glue products work, but I would always be wary of using them on any joint that is going to continually flex.
I suppose you could glue the wire to the tab with Nickel Print (or something similar), and after it sets, put a serious drop of JB Weld on there to really epoxy that wire hard in place.  I'd feel more confident about it if you did that.

[glakedylan]

one would think that drilling small holes in he tabs
connecting an eyelet connector to the wire
and the connecting that to the tab with a screw
that removes the need to solder in a sensitive area
the screw can be placed in a tapped hope
be self-tapping
or even have a nut to secure
that would make sufficient electric contact and connectivity

just my own thoughts and plans for some Mintrix tenders with Bachmann trucks

regards
Gary

[carlso]

Max & Gary, thanks for the thoughts. I have done soldering like this requires and I think I will do it again. Guess I am just being lazy.

Carl

[peteski]

Getting back on track ... (yup I just did that). 

Hey Pete I figured you had an idea on something to use. I saw this very pen in Radio Shack and debated on using it. To be honest I'd be surprised if I need anything beyond 300 F but I'm not sure. I'm going to use it on a motor brush. More on that later. How strong do you think the pen liquid is? Is it more like paint?

I think that for that type of application using a conductive adhesive (2-part epoxy) would make more sense.  I don't think the conductive paint has all that much strength.  Plus, the paint is solvent-based. The solvent might take a long time to fully evaporate when placed between 2 non-porous parts.  Epoxy hardens due to chemical reaction (no solvent to evaporate).

[LV LOU]

Nickel Print would probably work for that.  But to be honest, I would still go with a drop of paste flux, and some good
soldering technique.  When soldering fine wires to tender truck tabs, there is always a danger of melting the truck frames.
You need to be in and out in a fraction of a second.  File the tip of the tab super clean with a file.  Tin the wire with solder beforehand.
Put a drop of flux on the truck tab and tin it.  THEN you should be able to make that joint in the blink of an eye and not melt the frame.

I can't stress enough how important it is to first clean and tin a part & the wire first as Max suggests when doing difficult soldering projects.A well cleaned part will tin in a fraction of a second,and a tinned wire will then join to that piece just as fast.Try to have the extra solder needed to do the joint built up on the wire,not the piece you're joining to.This way,the solder will be hot and liquid before it touches the tab,and it will flow on instantly.Also,make sure your iron is HOT..I solder at about 600 degrees or more with my station,make sure the tip is small enough for the job,and is also well tinned..