axial flux planar stator

Oh ya, anyone know a place that sells rolls of copper foil (0.01" or

0.015" thick) that is backed with 0.001" or thinner kapton or similar? :) The thickest stock I've seen for this is for FPC flex print circuits and is 5oz which is about 0.0068" thick I believe, so looking for 8oz and up copper on thin plastic if it exists.

cheers, Jamie

We've made stuff like this (current shunts, delay-line position detectors) by photoetching manganin or beryllium copper. For the more complex/delicate structures, you leave webs or a "carrier" section of solid material around the outside to hold things together during handling, which you can dremel away after things are laminated or whatever.

Here's part of a 2-D delay-line anode thing, for imaging ion hits on a microchannel plate.

It's thin, soft copper, and is fairly delicate. This one has been kicking around for a while. I think some pancake motor rotors are made this way.

Are you spinning the magnets? That's a lot of inertia.

John

I would think that you would need to address the "compression" geometry issue first, as that would all but rule out the simple "plane per phase" approach - ie, the magnet energy required is proportional to airgap length, which is 3x longer than really necessary with the 3-plane construction. So the first thing is to get the radial legs of all 3 phases coplanar (where they pass through the flux), but allow a different form of interconnections, which has its own optimum geometry. Maybe put all the radials ion one side and all the interconnects on the other side of a 2 layer PTH PCB, then plate it up? Or maybe you can etch the radials on a plane and the connections on two tubes (all of very thin Cu+substrate, assemble them as a tight fit (so the traces touch) then heavily plate up the Cu and make the joints?

Tony

Hi John,

Looks very intricate, how did you keep the wires from going into spaghetti mode? :) What is the depth/thickness of that copper anode? I'd like to do exactly the same thing but only etch from one side and have a thin plastic backing on the other side to hold the wires in place.

Yes is a brushless outrunner design, lots of rotor weight :)

cheers, Jamie

first, as

magnet energy

necessary with

3 phases

Hi Tony,

I think if the sheets are flexible and the radials have a bit extra length it may be possible to compress them into more or less one plane at least in the area between the magnets. I am not sure though.

radials ion one

plate it up?

The PCB would have to be flex print technology to keep it thin I think, and the max copper thickness I've heard for this is 5oz standard, but is it possible to plate it up thicker in a plating bath as you say? I guess if the copper was left uncoated it could be put in a standard copper plating bath?

(all of very

heavily plate

That may involve a lot of work to assemble the inner and outer tubes and solder them to the radials I think but maybe there is a quick way to do it.

cheers, Jamie