Andrew Plumb wrote:
> This was the only stuff I could find which explicitly had an identified
> metal content. All the others were "metallic", or some variation which
> isn't necessarily conductive; it "looks like metal".
If it looks like metal, then it's very likely metallic. The conduction
electrons in the material have to be mobile enough to shield electromagnetic
waves from the interior, which is why metal shines. Plasma mobility at
visible optical frequencies generally implies carrier mobility at lower
frequencies as both require a conduction band (an unfilled band of electron
states).
> Don't know how well the stuff will work for making FCBs (Fabric Circuit
> Boards :-), so I'll just have to try and see. I don't expect it will be
> very efficient as power conductor, but should do fine for the slow-speed
> analog interfacing...
Actually, this sort of thread is fine for carrying medium-to-high-speed
transients to drive high-impedance CMOS inputs (== capacitive coupling). The
wrapping thread has a metallic core -- usually silver or aluminum --
passivated on both sides by colored mylar or polyimide. Therefore DC coupling
to this material is infeasible because it requires some sort of thin-film
vampire tap, while AC coupling works great.
Embroidery shops generally charge more if you request these "metallics"
because they're more difficult to run through the machinery without tangle
and breaks, so they require more manual intervention to complete a run.
If you want an efficient power conductor, use real metallic organza (obi or
sari material) along the conductive axis and fold it over itself to get
several conductive threads in parallel. This is what we did for power
distribution in the MIDI jacket to resistance down to < 0.01ohm/inch.
-Rehmi
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