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I found which uses what they call microcarbon rather then precious metals to make the glue conductive. It is about $4 for 1/3 oz. Others glue that use silver start at about $20.
I found which uses what they call microcarbon rather then precious metals to make the glue conductive. It is about $4 for 1/3 oz. Others glue that use silver start at about $20.
I just put a small tube of conductive epoxy back on the shelf when I saw the $30 price. I was after it to repair my rear window defroster. I'm glad I put it back, because on the long drive back home, late at night in the mountains, I 'totaled off' the car.
I found which uses what they call microcarbon rather then precious metals to make the glue conductive. It is about $4 for 1/3 oz. Others glue that use silver start at about $20.
A preliminary test shows that the resistivity of this stuff after it dries is
about 500,000 (five hundred thousand) times higher than copper.
This isnt very good at all, but still this does not make this stuff unusable.
At very small distances the resistance can be under 1 ohm, which is useful
for low current applications.
The other downside is the mechanical stability. It dries to the consistency of
dried clay, which is brittle and may break, or at least break loose of the
wire or device is was attached to. In the test, the initial resistance of
a sample of material measured 89 ohms, but after moving one of the leads
a little it rose up to 250 ohms (about 4 times higher). This again doesnt make
it unusable, but means some other means of mechanical stabilizing has to be
also incorporated, like coating with a layer of epoxy or something like that
so the leads can not move or bend near the material. The manufacturer
recommends super glue, but epoxy might be better.
What i dont know yet:
1. How stable the resistivity is over temperature.
2. How stable the resistivity is over time.
3. How stable the resistivity is over surrounding moisture content, which
would include outdoor applications.
4. Power rating of a resistor made out of this material.
In fact all i know so far is the resistivity, which is approximately
0.36 ohm inches, which happens to be over 500000 times greater than copper.
One little interesting experiment i did was to paint a path on an index card
and wait for it to dry, then connected an LED and 9v battery. The current
flow was 14ma and the resistance of the path was about 250 ohms.
Thus, this made a little custom value resistor
Oh ok, well i would be interested to hear about your measurments
and experiences too.
I looked around a little more too after doing these few tests,
and found other products like this one but are epoxy types which
would be stronger. The downside is that they are all much
more expensive, with the cheapest one i could find being 25 dollars US.
Surprisingly, that one had about 2x the resistivity of this one, meaning
Wire Glue is actually better for it's conductance than the 25 dollar one.
It's not nearly as good as the better one i found however, that was
38 dollars, as Wire Glue has 100 times more resistivity than that one
does, but the price makes Wire Glue attractive i think.
I did find that many connections could be made with a resistance
of just under 1 ohm, which is good for many things except
high current stuff. I dont know if i would use it with speaker
systems that put out high power though, as it might eat up
some of the power.
I also found the temperature coefficient isnt that good either, being
something like 10 percent, and it may take a while to stabilize, but
that too wont stop me from using it.
The main application I see for this soft of stuff is where soldering is not possible. Most often due to heat. What else are you thinking of ? Speakers ?
I imagine that heating is more of a problem than power loss.
P=I²R
I don't know what the heat capacity, conductance, emissivity or maximum temerature of this stuff is so I wouldn't like to guess the maximum current rating, anything over 250mA is probably too much.
I was thinking of using it for unusual stuff but would investigate the
use on various apps like speakers, audio in general, LED lights,
power supplies, and important: electrostatic shielding and electromagnetic
shielding.
I too would like to know more of it's properties, but i wouldnt go as
far as to place a limit on the current except in some specific application.
I think we do need to investigate it's power rating, and how bad it
heats up with use. I guess we cant expect too much because it has
got to be a relatively bad heat conductor too (much worse than
copper), but maybe with heavier application it might work better.
So all i know so far is that the resistivity is 0.364 ohm inches, and
it's temperature coefficient is around 0.001, but that 0.001 is subject
to change because when that measurement was made i dont think
the material was totally stable yet, and as i was saying before
it looks like it takes a while and maybe some temperature cycling
to get it to where a temperature coefficient measurement would
make sense. Let me post a few actual measurements so you guys
will have a better idea what happened when i went to measure
the temp co:
Code:
degs C R(ohms)
85 C 90.0
160 C 92.3
85 C 87.9
170 C 90.0
85 C 85.8
See above where the resistance of a sample started out at 90 ohms,
and after heating, cooling, heating, and cooling again the resistance
dropped to about 86 ohms and stayed there. This is a permanent
change and so it's not like other temp co's where the resistance
goes back to the original once the sample cools down. This tells
me something is happening to the emulsion, but luckily, the resistance
drops so that is probably a good thing unless you intend on making
home made resistors or precision trimmed voltage references, which
probably wont work out very well with this product. That wasnt
the intended use anyway, but it's still interesting to look at this.
I thought it would be really neat if we could set up a circuit board
(for one example) with say an LM317 on it, and use some of this
stuff to 'trim' one of the voltage set resistors to obtain a very accurate
output voltage of say 4.096, or even just 5.000 volts. That would
mean not having to rely on exact precision resistor values for some
hobby circuits that you dont want to have to purchase many values
just to trim in to an accurate voltage setting.
Of course i cant think of all the applications and how well it would
be suited to them, but i do believe that this stuff will be useful.
And hey, if you really cant solder something then you have no choice
except to go with a higher priced material.
BTW, one higher priced material i looked at actually had HIGHER
resistance than this stuff did, so before buying any of that stuff
anyone would do well to check the resistivity first.
I also read on the manu's site that they say they are working on
a similar material only in epoxy form. That will be even nicer.
I seen that too but I also see a date somewhere on the site that told me not to hold my breath. Do not recall where.
They have an interesting mix of products disposable fish cooking thermometers, microwave testers, and wire glue.
One of the pages on the site showed where they put some wire glue on the screw terminals of an old phone and made it work better. The idea of coating a male connector with it prior to inserting may make a better connection. I am thinking about old cars that do not get driven often. It would keep the moisture out and make better connection.
I don't know, if wire glue is somewhat brittle and there is any vibration, it may get pulverized and end up separating the male/female pins. Then you'd end up relying on the wire glue which has already been stated to be not all that great of a conductor. I'd stick to dielectric grease if your concern moisture.
Interesting idea 3v0 and equally interesting reply Noggin.
I'll have to give this some thought and maybe do a test for that too.
My most recent test was to cover the front and back of a sample
connected to two electrodes to form a resistor with some epoxy and
let it harden, on an index card. The epoxy wasnt put on too thick so
the construction was flexible. Measuring the resistance of the sample
it was 84 ohms, but after flexing the sample slightly it went up to 86
ohms and stayed there, even after the flexing was stopped so it returned
to the original flat shape. This tells me that it should not be allowed to
flex, but that a little flexing might not hurt too much so maybe it wont
crack. I'll have to do more testing though because this was a rather
thin sample.
BTW i just got this stuff yesterday so i still havent done that much with
it yet. I intend to keep trying new things with it.
As per these last two replies i think i should test for flexibility too.
Based on discussion in the comments, it seems like the author has quite a bit of experimenting to optimize his selection of materials and ratio of mix.
The short version: mix Carbon Graphite and Liquid Tape in a 1-1/2 to 1 ratio by volume
**broken link removed**
**broken link removed**
One advantage to this formulation is that it's not brittle, its more flexible/rubbery because of the liquid tape.
I've done a similar thing myself using blu tac and finely ground pencil graphite. I didn't use it to make a circuit, I just experimented to see what the resistance was.
Unfortunately it was awhile ago and I can't remember the resistance or the exact radio of graphite to blu tac.
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