Flex PCB Overlapping Branches – Component Placement in Overlap Region (Altium, 2

[Prasad_2001]

Description:
I am designing a fully flexible PCB in Altium where the main flex splits into two branches.

One branch (Yellow) bends 90° upwards
Another branch (Green) bends 90° downwards
Due to mechanical constraints, both branches overlap in a specific region (highlighted in red)

In this overlapping area:

Physically, both flex layers will occupy the same X-Y space, but at different Z heights after bending
Electrically and layout-wise, this region is currently the same PCB area

Refer image for details

My questions:

Is it possible to place components separately on both overlapping regions (i.e., one on top branch, one on bottom branch)?
Can this be achieved using stackup modification, layer definition, or rigid-flex techniques?
How can I differentiate these overlapping areas in Altium, since they belong to the same PCB layout?
What is the recommended industry approach for such overlapping flex geometries?

[Psi]

As far as i'm aware you just cannot ever do that, or make it.
It has to be something you can express as a flat surface for manufacturing

There are some options to end up with something like that though...
- Have two separate flex pcbs with pads that get hotbar'ed together into the overlapping shape.
- Have it fold up into that overlapping position from a non-overlapping flat layout.

[Someone]

What is the recommended industry approach for such overlapping flex geometries?

Two options:
work extremely closely with your specific board house to deliver what they can work with and achieve.
or...
Don't!

Overlapping rigid flex within a planar panel sounds insane, I'd guess most board houses would reject the idea immediately.

[Someone]

As far as i'm aware you just cannot ever do that, or make it.

I can imagine a few ways to do it, but the question is which PCB fab (and then assembler) would want to take the risks on a custom process ?

[Psi]

As far as i'm aware you just cannot ever do that, or make it.

I can imagine a few ways to do it, but the question is which PCB fab (and then assembler) would want to take the risks on a custom process ?

And also, who would want to pay the $$$ costs needed vs doing it a different way without overlap when flat.

[Psi]

i think they could hotbar it together as part of the pcb fabrication process, but if you wanted to do pick-n-place on both the overlapping segment i think they would through their hands up in horror.
They would need a custom jig for solder stencil and pnp that holds one overlapping area out of the way and put it through both twice.

[squadchannel]

I don’t know where the bending edges are.

However, I can say this: PCBs are not designed in a bent state.

They are designed as a completely flat. bending design is the job of other CAD software.
All PCB CAD software and PCB fabs create data based on the assumption that the PCB is completely flat.

[Prasad_2001]

Thank you, everyone for the detailed inputs.

Overlapping geometries don't seems practically feasible within a single PCB—especially from fabrication and assembly perspectives. This may change in future.

The suggestions around using separate flex sections or redesigning into a non-overlapping flat layout make sense, and I’ll evaluate those approaches further.

Appreciate the clarity and insights.