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Picture of Make Conductive Glue and Glue a Circuit
This is an instructable on the best conductive glue I have been able to make that uses easy to obtain materials, glues well to most materials, is quite flexible and has a low resistance. Unfortunately for me, it uses a rubber or plastic mixture that I do not know the chemical composition of, so I cannot patent it.

There are many kinds of conductive epoxies, glues, and rubbers available. Unfortunately, they are for the most part quite expensive.
So, for more than four years, I have been trying every possible combination of likely elements, compounds, and solvents that I could get my hands on, in order to make my own truly affordable conductive glue. While I have found several that have excellent low conductivity, they tend to be quite brittle and have a tendency to crack. The conductive glue presented here does not have these problems.

Because this glue is quite flexible and you can vary its resistance, it has potential for different kinds of paint on sensors for robots or other devices. It should be possible to paint on strain gauges on the outside of a regular glove and use it for virtual reality or other control possibilities. Touch sensors and membrane switches can be painted on various flexible or rigid surfaces.

It can be used to paint on wires and resistors and as a glued solder joint. It can also be used to paint on strain gauges, temperature sensors, electromagnetic shielding, antennas, and push-button switches. I suspect, that with more experimentation, it may be possible to use it to create capacitors, diodes and transistors.
 
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Step 1: Materials for the Conductive Glue and Circuit

Picture of Materials for the Conductive Glue and Circuit

Carbon Graphite, fine powder-Available in larger quantities at http://www.elementalscientific.net/

Available in smaller quantities at your local hardware store. It's called lubricating graphite and comes in small tubes or bottles. The brand I used successfully is called AGS Extra Fine Graphite, but no doubt there are other brands that will also work.

Performix(tm) liquid tape, black-Available at Wal-Mart or http://www.buytape.com

Mixing cups or glass container

1/4 and 1/2 teaspoon measuring spoons

Glass or plastic mixing rod

Cardboard for stencil

Toluol paint thinner (optional)-Available at most hardware stores.

Conductive thread (optional)-Available in larger spools at http://members.shaw.ca/ubik/thread/order.html It is available in smaller spools at
http://www.Inklesspress.com/electronic_parts_2.htm

Circuit materials of your choice

Step 2: Mixing the Glue

Picture of Mixing the Glue
After some experimentation, I have found that mixing the Carbon Graphite and liquid tape in a 1-1/2 to 1 ratio by volume, produces the lowest resistance. If you add more graphite than that, the painted line tends to become more brittle and can shrink and crack. An easy way to mix is to use several mixing cups and add 1-1/2 spoonfuls (using a 1/4 teaspoon) of the graphite into each cup. You can then wipe the measuring spoon and then slightly overfill it with the liquid tape. Pour and scrape this into one of the cups and mix up a batch. It is best to mix up one small batch at a time as it tends to dry very quickly and can get gummy fast. Mix it fast and be sure to get all the carbon mixed in well before you use the glass rod or a toothpick to apply it to the circuit you are creating.

WARNING: This process involves nasty solvents in the mixing process. Be sure to mix and apply either outside in the shade or inside in a VERY WELL VENTILATED AREA. Avoid contact with skin until the solvents have completely evaporated (The next day).

Step 3: Applying the Glue

If you want to apply it in one coat You need to apply the glue when it is almost the thickness of peanut butter. You can use the Toluol paint thinner to thin the mix if it starts to get too gummy or if you want to paint it on thin. Toluol can dissolve some plastics, so you should mix it in a glass container. The thinner the coat the higher the resistance you will get. This is ideal for painting resistors. Generally, if you paint on a second coat you will cut the resistance in half. Up to a point, each successive coat will reduce the resistance of the conductive line or resistor.

Like most conductors, the resistance of the glue is roughly proportional to the cross sectional area of the conductor. In this case, a glue line about 1/4" wide by about 1/16" inch thick will have a resistance of about 32 ohms per inch. While this is not that good for running power to the main circuit, it quite fine to run digital signals or to light LEDs. By comparison, an equal amount of "Wire Glue" has a resistance of about 90 ohms per inch.

Step 4: Creating Components

Picture of Creating Components
You can create a line stencil by cutting a 1/8" or wider slot in a piece of cardboard and painting in the slot. To create resistors you should first test your mix between two wires taped an inch apart. Let it dry overnight before you measure the resistance. Even when slightly wet, the resistance will be higher. To create a resistor I use a mix of 1/2 graphite to 1 liquid glue or of 1 to 1. To increase the resistance add less graphite to the mix or make the line less wide or thinner or longer.

See fig-B. To create a strain gauge (a resistor that varies resistance as it is bent), you can lay down a coat of liquid tape on a piece of flexible plastic. When it is partially dry lay down a coat of conductive glue between two wires or pieces of conductive thread that are about an inch apart. After that has dried, lay another coat of liquid tape over the whole thing. The strain gauge in the picture has a resistance between 70-300k ohms as it is slightly bent.

The strain gauge or a glued resistor can also be used as a temperature sensor. If it is taken from the shade into the full sun, the resistance increases. So, it could be used to measure the difference between room temperature and overheating conditions.

To glue two wires together, if you can, you should first twist or crimp them together and then coat them all the way around with conductive glue. If you merely lay them side by side without touching and then glue them, the resistance of the glue joint will be in 7-9 ohm range. See fig-A if you are using conductive thread (resistance is about 2 ohms per inch) for wires, you can tie an overhand knot to the wire you are connecting to and then coat all around it with the glue.

In fig-C you can see that it is also possible to glue surface mount LEDs.

Step 5: Glue a Complete Circuit

Picture of Glue a Complete Circuit
Here you can see a circuit that was glued onto a clear plastic cover. This simple working circuit uses a Picaxe microcontroller to flash 4 lights in sequence. It is used only to illustrate the concept, obviously you can choose your own integrated circuits and make the circuit of your choice. Be very careful when gluing onto the IC pins as the black glue can be very hard to see if it gets on the black IC and can end up shorting the pins.

In this circuit I used conductive thread to provide power from the batteries. Conductive thread is flexible and glues quite well, but you could also used tinned wire. Magnets in front and back, hold the conductive thread to the two batteries and act as a battery holder.

Step 6: Possibilities

Picture of Possibilities
This conductive glue is a fraction of the cost of any other conductive glue including "Wire Glue". You can mix it up in large quantities. As you can see, I have barely scratched the surface of what is possible with an inexpensive conductive glue and glued circuits. Perhaps these circuits could be silk-screened on. Maybe one could paint glue on a surface and then use a laser to remove where you don't want it to conduct and etch a circuit that way. Circuits can be constructed on various 2 and 3 dimensional surfaces including paper, cardboard, plastic, fabrics, and glass. As mentioned above, many components such as capacitors, diodes and transistors might also be constructed.

While I have experimented with at least 157 different chemicals, metals, solvents, or elements, I have not tried most of them with the liquid tape. So there is ample room for those of you who like to experiment to improve upon the mix.

For those of you who would like to see a movie of this simple circuit that uses a Picaxe controller to blink 4 LEDs in sequence, you can download an video file at: http://www.inklesspress.com/glued_circuit.wmv

Step 7: Update

Picture of Update

Thank you for your feedback in the comment section. This is an open source conductive glue so I tried some of your suggestions and the results are:

Lubricating Graphite
The lubricating graphite resulted in a resistance equal to the graphite from a chemical supply. However, it is quite a bit more expensive for the amount of glue you get. If you just want to see if it works or only need a small amount of glue, it works fine.

Wire Glue
Wire Glue works well. Even though it is the cheapest of the conductive glues and epoxies that I have seen, It is more expensive and has a higher resistance than this open source glue. It also is brittle and will crack if you bend it. You cannot as easily vary its resistance. But it works just fine if you only need small quantities. On the plus side, it has no fumes and sticks very well to glass. You can obtain it at:
http://www.goldmine-elec.com/

Metals Instead of Graphite
I have had mixed results in my experiments with powdered metals. While they often produce the lowest resistance per inch, they tend to make the resulting mix quite brittle. They also considerably increase the price of the glue mix. If you would like to see a list of the metals I have tried and the results along with the latest update on Conductive Glue Experiments, you can see them at: http://www.inklesspress.com/conductive_glue.htm

My original goal was to come up with a glue that was less expensive, had a lower resistance, and was more flexible than the nearest comparable commercial product. While there is room for improvement, this glue is as useful as most of the off the shelf conductive glues. As for me, I am quite happy to continue experimenting with the proven graphite formula which has low cost, high flexibility, variable resistance, and many possibilities.

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what can i use insteard of performix conducting tape
olrob3 years ago
I am trying to connect to the + and - of a battery cell. These are calls I obtained by taking apart battery packs (14.4 V and 18 V). When done properly the tab which is welded to the battery posts is obtained and one can solder to the tab. Sometimes the tab comes off and I have nothing to solder to for connections.
Could i use the conductive glue you have explored to connect a copper tab to a battery post?
The glue needs some strength and low resistance and carry some amps of current.
Thanks, olrob
mikey77 (author)  olrob3 years ago
Sorry.

This glue has too much resistance to carry large amounts of current.

With amps it will start to smoke.
olrob mikey773 years ago
Did you try grinding a silver spoon (knife, fork) and collect the silver particles? There are a number of silver epoxies around with excellent conductive properties. I was inquiring about one that I could buy for $25 for 5 grams but that weight corresponds to about 2 dabs ( two trials) with a dab of the epoxy between a cell post and a copper strip which is very expensive.

gaieb olrob1 month ago

If you find a spoon that is real silver and not just plated, you will be better off selling it for the silver and buying alunimum powder or copper powder to use for your conductor.

olrob mikey773 years ago
Thanks Mikey77. when I measure a 1" tab that is welded to a + or - post I get 1.4 ohms from one end to the other with alligator clips on each end. Does any of your trials have a resistance near 1.4 ohms?

A 14.4 V Craftsman NICD battery pack delivers from 1.2 to 2.2 amps (quality & price). It contains 12 1.2 V cells in series. NiMH cells can produce 3.2 to 4.5 amps at 1.2 V. Li-Ion cells are rated at 3.6 V and 2.6 amps each.
One of my applications is a Skil Twist battery powered screwdriver. It uses 2 NICD cells in series for 2.4 V and 2 amps in an intermittent operation. I would guess that each screwing operation would have 30 seconds on and 30 second off.
My Craftsman 14.4 v power screwdriver would work about the same (2 amps for 30 seconds).
Would your lowest resistance mixtures still smoke with a 2 amp 30 second cycle?
Thanks again.
cgosh olrob2 years ago
IMHO, trying to use makeshift materials as a conductor for high-current circuits is a mistake. I found that my local Batteries Plus store makes custom battery packs by spot-welding tabs to their rechargeable batteries. If your tab has fallen off, see if they'll put it back on for you.

This instructable has tremendous value for low-current devices in creative uses. I've had great luck with Circuit Writer pens from Mouser and Radio Shack, but they're expensive ($20), have a small quantity, and dry out in about a year.

If you want to try your luck, consider adding surface-mount LED's, capacitors and resistors directly to the pins of a mini-DIP package. I once did this with a 556 timer, using bits of adhesive tape barriers to create power rails and conductive zones.
olrob olrob3 years ago
I see that 3M™ 1181 EMI Copper Foil Shielding Tape has excellent conductivity (.005 ohm) and it's solderable. A small piece of the tape could be bonded to a battery post and a tab could be soldered to the tape. Their conductive acrylic pressure-sensitive adhesive is the key. Have you tried anything like that?
Thanks
LaserDave olrob2 years ago
Unfortunately, this method won't work. While the tape itself is capable of carrying the required current, the problem comes from the adhesive side acting as an insulator. The only way to connect to the copper tape from the adhesive side is to clean off the glue and scrape away the oxide-like material just beneath it. Even then, it's difficult to get the tape to contact the battery with enough force to make a good connection.

Getting foil tape to make a good, strong connection to a flat surface is a challenge on its own... especially when higher currents are involved. One of the best ways to do this would be to use a small spring taped to the end of the battery, then slip the tape or wire under the spring to remain tightly fixed against it.
MarkB82 months ago

Really interesting, thanks.

Cute, but fake., I just burned some wood, tested with ohm meter, there is no conductivity at all. You can't make conductive carbon by burning wood. I'm sure there's a way to make conductive glue, but probably by using metal shavings or something similar.

you do know that it advertises the liquid tape as an INSOLATOR right?

Once you fill an insulator with a conductor though, it conducts. Rubber insulates too, then we jam a piece of copper through it and sell it at home depot as "insulated wire".

Okay, so we don't jam it through, we coat the copper, but same point.

mikey77 (author)  homebowyerboy7 years ago
Yes, Liquid Tape is an INSULATOR. This instructable is about how you can turn an insulator into a conductor. Liquid tape is an insulating rubber which can be turned into a conducting rubber with the addition of carbon graphite.
BlensonP11 months ago

Good job, Keep it up. Very helpful :)

Thanks for sharing!

Sitherus1 year ago

very helpful. As you may know when flowing schematics the wires in real life are always so much more tangled and messy but now they don't have to be.

tstirling1 year ago

I wonder if a mixture of copper filings and graphite might give you a lower resistance while keeping the ductility you achieved with this mixture…?

MY DREAM COME TRUE !!!!!!!!!!!

PS:can it be used for genral soldering

Machine1 year ago

If it really is that good, then you should be able to make the product commercially then why don't you? It could be made to dispense from a tube with a dispenser that enables a thin circuit to be laid down.

AJMansfield2 years ago
Did you try using more than 1-1/2:1? Perhaps it would be even better.
It's like soldering with no heat. :P
Guavaman3 years ago
I have two keyboards that were damaged by water spills and was looking for a (cheap) way to fix them when I came across your article.

Being cheap, I first tried a variation of the conductive glue idea using filed aluminum from a soda can aand clear paper glue, but it yielded 0 conductivity. I was forced to spend $2 on the lubricating graphite and try again, still with the Pentel brush glue as the base. It worked, but very weakly. The resistance was so high 2 AA batteries could barely make it through to light up an LED. I then tried wood glue as the base but came up with 0 conductivity.

Sadly, my attempts at being MacGuyver all came up very short. I went out spent $8 bought some black liquid elec tape (Blue Magic brand) and tried again. YET AGAIN the conductivity was very poor, although slightly better than with the clear paper glue. But it was still too weak for a the chip in the keyboard to detect the signal. Unless I'm doing something terribly wrong, the graphite just doesn't seem conductive enough for almost any purpose to me.

My last attempt involved gluing a staple to the keyboard membrane over the bad trace which looks like it is allowing slightly more current through. I have to wait for it to dry and see...

Any of you thinking you can use this in place of solder, think twice.
Luziviech3 years ago
Umm. I want to make sum conductive adhesive, too, but i dunno where to get Performix as i'm outta USA, nor do i know what i can use instead. Second problem i got is: what is the graphite for and how do i dose it? I came along sum other howto ( http://smackaay.com/2009/01/13/making-a-conductive-adhesive/ ) and so i got sum useful glue plus the mentioned iron filings, but yet no idea for the graphite's use and its amount.
I would really appreciate, if you could help. Though knowing instructables, i came here via your website and i'd say that the pict of your trials with different materials are proof enough of your competence, so maybe could you even give a comment about the benefit of the alien howto?

Greetz,
Luke
motleyjust3 years ago

Nice I can use this. Thanks.

The link http://www.Inklesspress.com/electronic_parts_2.htm
for smaller spools conductive thread doesn't work.


this should work with other plastics and epoxy resein right?
Yes, but you will have to try your own formulations. I have tried with pva school glue and an organic-solvent-synthetic-rubber glue, but this late one is more hard to handle because it cures to fast. I have tried epoxy resin also and it performed very badly.
Have you tried hot glue?
No, but I guess it will not work. I cannot even imagine a way to do it, maybe you will have to make your own sticks with metal powder heavily embedded on it.
You could make a mold of the glu gun sticks, melt the glue, mix in the graphite in and mould it back into shape
how well did the school glue work?
It works well to make paper circuits, check it at: http://www.youtube.com/watch?v=D2l9fKVTICw
xile63 years ago
I didnt read all the comments but has anyone tried metal shaving? I work on cars and ive grind down some pipes before. And im left with this metal dust. So couldnt i use that alone with the glue?
Agentfern xile63 years ago
You probably could, i dont see why not.
Exocetid3 years ago
Excellent Instructable and you "did an Edison" in your search for a solution to a common problem. Bravo!
What are you using for this circuit, where is you diagram? Interesting instructable, but it could use a little more explanation. However, if you have included these things, they are so buried in words it's nearly impossible to find them. ie: clarification, please!
thetapeworks.com doesnt supply liquid tape anymore...
buytape.com does though, and its run by the same people

btw, love this idea!!
Thanks.

I have made the correction.
no problem
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