Conductive Glue in Lieu of Soldering?

[C855B]

Has anybody here tried conductive glues instead of soldering?

Trying to solve a challenge wiring nano LEDs, I picked-up a tube of Radio Shack Conductive Wire Glue. It didn't work for my particular problem, but it is making me think about other common MRR issues such as track feeders.

This particular glue appears to be powdered metal suspended in a very thin, watery base. It's not cyanoacrylate, and instructions say "overnight" to cure - pretty accurate, it was several hours. It has absolutely no tack while drying. It's either runny or solid, so any work must be clamped. It cures hard, but when it dries it adheres amazingly well to non-porous surfaces. My test was on glass, and I had to work at scraping it off. The consistency and behavior reminded me a lot of red Loctite, so it is probably some manner of air-reacting polymer.

My concern about using it for track feeders is threefold: first, clamping everything into position without gluing the clamp to the joint. Second, the wait. Finally, the hardness, so hard that it seemed brittle - could it handle the vibration? However, it dawned on me as a possible alternative to soldering rail joiners, for those so inclined.

Interested in hearing others' experiences with this or other conductive glues.

[John]

could be good for putting resistors on wheels

[Ken Rice]

I tried conductive glue for attaching point jumpers.  The stuff I tried was called silver conductive epoxy.  It's billed as having a resistance of 0.38 ohms per cm.  I'm not sure exactly how they define that (how big a glue blob, etc).  When I tried to glue a small wire across a gap in code 55 rail to test the idea, it was a bit tricky trying to glue the wire without getting glue where you don't want it.  I ended up measuring a resistance of about 2 ohms across the gap.  In my opinion that was too much.

I finally settled on using resistance soldering tweezers and solder paste to attach the point jumpers, which works quite well.  I wrote it up on my blog: http://rices-rails.blogspot.com/2015/01/point-jumpers-and-track-feeders.html

[mmagliaro]

I have tried a number of these.  The stuff is not easy to use and if you can solder, always do that instead.

I use Nickel Print to repair Kato Mikado 1st generation drivers where the bronze fingers on the backs of the wheels don't make contact with with the wheel rim or with the axle center (it usually fails at both points).
I do this because it is impossible to solder to the hub or the rim, especially considering that there is a plastic wheel center that will melt if you try.

After mixing it very thoroughly (like, stir for 60 seconds and don't cheat), I can usually get the resistance
of the wheel-to-axle path down to under an ohm.  It takes work and patience.  Sometimes I don't get
it good enough and have to chip the stuff out of there and redo it.  The same company, MG Chemicals,
makes Silver Print, which has less resistance than the nickel-based stuff I am using.  But it starts getting really
expensive.  A small jar of Nickel Print is about $15.  Silver Print costs somewhere near $50 per jar.

Like I said, for track feeders, or anywhere else where conventional soldering can be used, DO IT.  These glue-based methods are great things, but only when soldering is not an option.

Oh.. and don't even bother with the cheaper carbon based conductive glues.  The resistance and current-carrying
capacities are far too low.  If you want to paint a path on the inside of a loco shell to connect an LED, yes, they
would work great for that.  But not for much else.    And I would be very dubious of connecting an
SMD LED this way, for fear that the tiny tiny glue connection point would come unstuck.   On a loco wheel back,
I can get a pretty large contact area.   But you can't do that on the tiny edge pad of an SMD LED.

There my $.02 on the subject.