The previous log detailed the screen FPC extender, used to adapt the stock LCD screen to the FunKey main PCB.
Before launching the FPC fabrication which is quite expensive (~ $100 / 5 pieces), we decided to have a dry run using a paper mock-up. Here is the result:
We covered the old Rev. A PCB with a paper print of the new Rev. B one, and created a paper version of the flex, gluing the connectors on them at the right positions. As you can see, the result is not too bad.
This was until we tried to open the lid flat:
Well, the FPC is a little bit too long, causing a “wave” that totally defeats the original purpose of the “flypaper design”: the small bend radius would certainly cause a failure sooner or later.
Moreover, the FPC is a little bit too wide, too, so it interferes with the internal ribs somehow.
So, back to the drawing board, we decreased the length by 2 mm, and the width to 4 mm, here is the result:
Much better! And the behavior when opening / closing the lid is also improved:
Here are the corresponding layouts: