Rubber Breadboard (Silicone Circuit)

Get all the functionality of a regular breadboard but in a fun, flexible bouncy form factor!

A full rubber Bread-board is nice because electronics can be pressed into the rubber nicely, and once you have your circuit set, you can adhere the breadboard directly to a silicone sculpture.

Plugging electronics into the rubber has some advantages

A) You can have more unlimited numbers of wires plugged in

B) The rubber grips your wires and holds components in place better (no falling out when shaking the breadboard)!

C) it doesn't fill up with water and corrode when left outside

Plus, with a rubber breadboard you can make the transition from test-circuit to permanent quite easy by just potting the full design in silicone once you get your circuit functioning in the correct manner.

****Note this is a smaller instructable broken out from the full instructable all about Silc Circuits: www.instructables.com/id/Silc-Circuits-High-Perfor...

Step 1: Mix Your Conductive Silicone

The Recipe :

(Contributed to the Public Domain 2015)

Materials

· Platinum Cure Silicone ( Smooth-On Sorta Clear 40 $30) (will also work with cheaper, tin-cure silicone)

· Chopped Carbon Fiber (1 - 6mm max e.g Tenax 2 2lbs for $30) ***

· Rubbing Alcohol

Tools

· Butcher Paper (Lay it down to not get everything sticky)

· Disposable Cups (to mix in)

· Multimeter

· Mixing Stick (This stainless steel spatula from mcmaster is my favorite for silicone)

· (optional) Conductivity Testing Mixer (Make Your Own in Later Steps)

Process

1) Mix a small spoonful of chopped carbon fiber with a splash of rubbing alcohol. (just enough to get it wet)

2) Disperse the hairs. Stir it up real good, the alcohol will break apart all the little hairs, you can see them separate.

3) Let the alcohol evaporate

4) Add some of your dispersed carbon hairs to a cup of your Part A Silicone Mixture Goo

5) Mix REALLY WELL. Test the conductivity every-now-and-then to see when the mixture gets conductive. If you are mixing well, the goo should be gray with a metallic silver sheen.

6) Add Part B and Mix well again!

***Remember to use basic safety precautions when handling carbon fiber. The fibers themselves are non-toxic, but can be bad for you if loose ones get in your eyes or lungs. Wear a facemask when mixing up dry carbon fibers. More carbon fiber safety info here: http://www.protechcomposites.com/pages/Working-Wit...

Step 2: Make Conductive Rubber Wires

A useful item to have when making silicone circuits is conductive bits extruded into long thin wires. You can leave them bare, or dunk them in some regular silicone to make insulated wire (just like regular wires). To make them, you squeeze silicone through a caulk gun, into a small tube. Let it cure in the tube, and pull it out! It's a fun conductive noodle!
To make insulated wires, dip into non-conductive silicone and let cure.

Step 3: Load Into Breadboard Shape

I had to split my conductive wires in half (because my tubing was too large) in order to get the proper spacing of a regular breadboard.

When you have these insulated bits, load them up tightly next to each other in some sort of container to hold them together (i found a nice box). I used NON-CONDUCTIVE rubber bits to create the gaps splitting areas of a traditional breadboard.

After everything is in place, just pour some silicone on top to pot everything together!

Step 4: Wire Up Your Circuits!

It's real easy! Just poke wires into areas next to each other!

Step 5: Future Versions

Future versions might let us do this much easier, and just create a shape that we can load the conductive silicone into.

My first attempt to cast the silicone directly into a breadboard did not work because of the tiny areas involved. If I want to cast such small bits directly, I probably need to source a smaller length of chopped Carbon Fiber (like 1mm). http://www.tohotenaxamerica.com/shortfibers.php