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Flex PCB questions

Hi Group,

I am in design process of a 12 layer board. This is first time i need to design embedded flex pcb for my design. This board requires a two layer flex pcb which is embedded in some of the layer of the board. I have discussed with pcb manufacturers in china but they usually answer questions when board is already made. This maybe because of the language barrier we have between, and due to time constraints i cant afford to go for this approach, that i first design pcb and then let the manufacturer find errors in my design.

My board looks like this: ======Rigid PCB=======------FLEX PCB----=====RIGID PCB====

Following is the 12 layer Stack which i plan to design:

  1. Top Signal
  2. Power Plane
  3. Mid Signal1
  4. Mid Signal2
  5. Power Plane
  6. Mid Signal3
  7. Mid Signal4
  8. Power Plane
  9. Mid Signal5
  10. Mid Signal6
  11. Power Plane
  12. Bottom Signal

Total thickness required for the Rigid pcb is 1.25mm

Questions:

  1. I need to know how embedded flex pcb are designed
  2. Can someone tell me how do i select which layer to choose for embedded flex pcb in my pcb stack?

Best Regards,

Asim

Reply to
asimlink
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Sorry I can't help, but I am curious as to why this is done - anyone know? What is the point of a flex PCB inside a rigid one? Or does it stick out one end or something?

--

John Devereux
Reply to
John Devereux

This looks to me as if you want a flex PB to connect two normal rigid PCBs - so the flex is not embedded in a single rigid PCB.

I would treat the flex PC as a cable, to be attached to the rigid PCs with a suitable connector, or soldered to some pads on the edge of the rigid PCBs. The flex PCB would then connect to the top or bottom signal layers of the rigid PCB.

--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
Reply to
Peter Bennett

OK I see now - I missed the ASCII art sketch somehow (and in fact I suspect it can't be done like that).

--

John Devereux
Reply to
John Devereux

Usually, it is because the two boards need to be either at an angle, or folded one over the other. If I were doing it, they would be designed as three separate boards, with the flex board connected via a connector at each end...

Charlie

Reply to
Charlie E.

=3D=3D=3D=3DRIGID PCB=3D=3D=3D=3D

Dear Friends,

I definitely would love to design it as separate boards but reality is that the board has to be made in the form factor as i mentioned in my last post. Charlie has well explained the reason why we need to do it that way. There is already a board made in this way and I need to revise the design with changes to circuit in the same form factor.

Regards,

Asim

Reply to
asimlink

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to

=3D=3D=3D=3D=3DRIGID PCB=3D=3D=3D=3D

Dear Friends,

I have found this manufacturer which makes such kind of pcbs and they call them Rigid Flex PCBs.

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But my question about which layer to choose for embedded flex pcb in my pcb stack? remains un answered.

Regards,

Asim

Reply to
asimlink

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to

=3D=3D=3D=3D=3DRIGID PCB=3D=3D=3D=3D

I have found an interesting article on rigid flex pcbs. i am reading it to understand what i need to do. i would like to share with the group:

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Regards,

Asim

Reply to
asimlink

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