I cracked it with pliers and tore it in half. Pretty interesting. Most of the thickness is a rigid black resin (?) plate. On top of that is silicon, badly chipped and spalled. Through my dissecting microscope, I can see rows and columns of short little lines. Data sectors, I guess. :-)
There's very thin PCB on top of that, a layer of what might be carbon fiber, and then more thin PCB. It has a diagonal lattice of metal, with channels carved out for the traces to run in. And then some top coat.
(I can try to get a picture with my macro lens. I really wish I could get a photo through the microscope...)
I don't know why it has this diagonal lattice. Every place there's a trace, there are two other metal curves that follow, on either side, forming a boundary of the latticework.
I'd be curious if anyone who is familiar with this stuff knows why they did it this way.
@varx Maybe it's an attempt at RF shielding?
@varx According to this article 90 degree turns may have etching problems.
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