2oz 2 layer flex pcb flex to fit limitations

[OwenH]

Hi,

I have a 2oz copper 2 layer flex PCB design with wide traces paralleled top and bottom for current carying ability.  The PCB is designed 0.5mm longer than the ideal distance between the surface mount connectors at the ends to allow any dimensional tolerance when mounting to be taken up by the flex pcb.  the enclosure is precision machined from aluminium. Once installed the pcb will no longer be able to flex. 

I realise that 2oz copper and 2 layers with wide over under traces is not at all ideal for flexing a flex PCB.  I just need to make one partial radius in the middel of the flex area which will be 20x (12mm) the thickness of the pcb (.26mm). The length of the bend area is about 20mm long and 23mm wide. The radius would be bent before install and allow it to stretch a bit while being installed and take up any tolerances.

How rigid will this flexible pcb be? Also how much spring back is there likely to be? I figured I would 3d print a part to aid in making the bend before installation in the enclosure, I assume I would need to add some overbend to make up for the spring back.

The images are of the flat pcb before a bend is put in. Two of the images show the assembly with the flex pcb flat and the second connector right of its location to represent the extra length in the flex pcb that would need to be taken up when bent.  The bend area would be between the 4 radiuses. The total length of the PCB is 54mm.

Thanks!
Owen