Conductive Paint Lessons
Lessons on Conductive Paint
Related to Pulse Choker Hack Notes for July 15th, 2009:
"We tried silk screening silver conductive paint (MG Chemicals 842-20G) onto two different types of fabric, a water resistant one and a water proof "leather like" one. Both showed very high resistance (higher than the meter can read) even for very short thick traces. It looks really cool though - hopefully we can figure out what we're doing wrong, and make this work. We also tried measuring the resistance of a huge dollop of paint on the spoon: silver = infinite resistance (!), copper = 200kOhms. It didn't matter if the paint was dried or wet. Note that we shook the bottle prior to use to ensure that the silver particles were dispersed evenly."
Types of Conductive Paint
- Opaque paint
- Nickel (Ni):
- Higher resistance - ~5-6 ohms per square
- Cracks when dried and flexed - Desktop Fabrication: Wearable Electronics Circuitry
- Copper (Cu):
- Higher resistance - ~5 ohms per square.
- Reasonably priced - ~$30 for 4 oz
- We bought CuPro-Cote #292-4 from Less EMF Inc., which wasn't viscous, not even quite as viscous as tempera paint. It also forms subtle flakes and could potentially crack like the Ni paint.
- Silver (Ag):
- Low resistance - ~0.1 ohms per square according to Desktop Fabrication: Wearable Electronics Circuitry. The type we bought (MG Chemicals 842-20G) promises 0.2 ohms/mil (or ~7.9 ohms/mm)
- Expensive - ~$30 for 0.7 oz (20 g) from Less EMF Inc.
- Nickel (Ni):
- Transparent paint
- Orgacon from Agfa - conductive, can be flexed, transparent, can be silk-screened
- Wire glue - $4 for 0.3 oz
- Conductive pen
- Shake paint well to ensure metal particles are well dispersed. Better yet, stir it a lot!
- Keep ink wet while working with it. If work time is protracted, mix paint frequently
- Resistivity measures are suppose to be accurate only when paint has fully dried
- Some paints are more dilute than others. One guy used silver paint, which bled beyond his mask (accelenation.com).
- Auto repair
- It may be cheaper to purchase conductive paint as the rear window defogger paint at the auto store. I haven't done so. Most defoggers use copper paint.
- Microscopy, i.e. scanning electron microscopy (SEM)
- Companies specializing in SEM equipment note that some paints particularly plantinum may need to be placed in an ultrasonic bath for a few minutes (SPI Supplies)
- Microscopy often utilizes different concentrations of metal particles in conductive paint, so these websites can provide you with a gradient of resistivity in their inventory of paints. M.E. Taylor's SEMicro division has three concentrations of silver paint: 18%, 36%, and 50% Ag.
- Paper Circuits by Leah Buckley: conductive paint, magnetic paint, magnets
- Paper printed circuit board by Peter Blasser