My SUPER tiny 6-layer PCB Motor is spinning! Here's the full video describing how I designed it:
My original 4-layer PCB motor had a 16mm diameter. By adding two extra layers I was able reduce the number of turns per layer and get it to 11mm. The total height of the motor is 3.6mm and its weight is 0.5 grams.
No space is lost in this PCB! Each coils have 3 vias to connect the in-between layers. These forced a triangular shaped stator poles, which utilize the magnetic field area more efficiently.
The tiny rotor design has four press-fit 2mm n52 magnets and a 3mm bearing. This new design has the shaft soldered onto the stator, so it is fixed and don't rotate with the rotor.
I had chosen to go with this design because of two things:
1. I couldn't find a bearing small enough to fit in the middle of the stator.
2. I'm not planning to use a shaft. Customized 3d-printed rotors makes much more sense.
The phase resistance of this motor was measured to be 15ohms and its getting to 85℃ with a 4V supply, so it should be perfect for a 1s lipo.