Hmm, I'm not convinced, even if you manage to bend this arrangement without breaking it. How do you plan to attach this inside the enclosure? What stops the side-panel PCB from sticking out a strange angle or flapping in the breeze?
And what's wrong with a little stack of two boards, held together by one or two pin headers?
I absolutely love feedback and insight from other folks, this is exactly why I discuss this in an open forum. So thank you for replying.
This is an experiment which, if it succeeds, will pave the way for another project of mine which involves a stack of four boards and close to 50 contactpoints between each board and possibly in larger quantity. Contactpoints equals potential failurepoints and extra expences. The posibility to set up and manufacture only one board will also keep down price for both PCB and PCBA. All things regarding to development/repairs/calibration and revisions will also be much simpler without having to remove soldered headers for dismantling. Maby not a valid point in a finished product with non servicable parts, but worth mentioning anyhow.
20mm long and 6mm wide for a twist of 90 degrees, as the OP mentions, is probably not at all feasible for a comercial product. But with multiple elements (and lots of U-turns) this could be done if the space permits.
I have already made some promising experimenting and testing on 1.6mm FR4, and my conclution is that a length/width-ratio of minimum 40:1 (200mm long and 5mm wide) will twist to 180 degrees without problems, and of course 20:1 for a 90 deg twist (no signs of cracking after "endless" manual twisting). To accomplish this ratio the solution can be the use of multiple "elements" In my attached PCB I have a lenght of each of the four elements of 48mm and a width of 3.6mm (total L/W-ratio>53:1 for a 180 deg twist). This will hold +/- 10 traces on each side (apart from components placed directly on the elements). I would recommend an extra 50% substrate in the turns (only 36% on this PCB) to resist bending and emphasize twist. Cracking and damage to the traces is definitively most at risk in the "inner turns", so it is wise to route the traces as far out as possible. I have the exact same lengths on all the elements som my theory is that the "sidepanel" will be "centered by design" and the opposite forces cancels eachother out. I am actually very confident this will be the case, that the middle board vill be exactly centered in all directions with twisting of the top and bottom board. It is not much space for this to move either way regardless of this. The top and bottom will be held together with two soldered "legs" between them which I have "forgot" to provide holes for on this PCB. Both the enclosure and the PCB got som screw mounting holdes. I really need the space for batteries and a chargingdevice, so I will avoid using the void in between for standoffs, but the enclosure in itself will probably also hold things tight together with the constant "pressure" from the twisting elements. Although probably not much pressure left from 3.6mm wide, 0.6mm FR4.
On a sidenote I will also mention that the LED`s mounted on top of the twisted element will be manually soldered on at correct viewing-angles _after_ the PCB is twisted and fixed into its final shape (because solder does not twist well). But this is solely related to my specific design, and not a matter of this discussion.