So there's a reason we aren't doing this... Right?
TLDR: If we can vapor-deposit parlyene, gold, and photoresist we should be able to make extremely thin flexible implantable electronic devices.
So rather than creating PCBs for all our implantable electronics needs, why not start off with the biocompatible coating as the substrate? In the paper I posted below the authors created an electrode array by using a 2-micron sheet of parlyene as the substrate (which I assume was vacuum deposited), onto which the gold circuit was additively photolithographically patterned (photoresist deposition -> gold deposition -> exposure). The main thrust of the paper was the use of organic transistors to record brain activity, so I'm not sure whether it would be difficult to integrate traditional CMOS components (microcontrollers, LEDs, other SMD components) onto a gold circuit on parlyene, seeing as how I've got no clue how to deal with making PEDOT::PSS semiconductor components much less the board itself. But at least making the circuit board doesn't sound impossible. I'm guessing the hardest part involves the vacuum deposition of each of the materials. @chironex on a scale of 1 to difficult how difficult would it be?