So, you think you might want to do some Flexible Printed Circuit layouts? Pull up a chair; there’s a lot to talk about. The first thing to know about FPCs is that they are almost entirely different from rigid boards.
As much as 90% of the effort is on the mechanical side with 10% place and route. That doesn’t mean that the Electrical or Mechanical Engineers are going to be much help. These things are an enigma to pretty much everyone. Count on re-routing it a few times anyway.
For starters, there’s the 3-dimensional space puzzle. To visualize the twists, turns and bends that a flex circuit can and will do, it’s common to use origami techniques to “paper-doll” the connectivity.’
Start with a piece of paper and a pair of scissors. Represent one connector by marking off pin-one. Create the general shape of your mock-up. Mark off the other end of the signal while in the final folded form. Flatten the paper out and see if you can draw a coherent line back to the other pin-one. Do this floor-plan thing again before taping out.
If you’re able to use pin-one for the same signal through the entire system, you’ll have fewer catastrophic failures.