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I want to move to flex-rigid PCB design for our product, to eliminate need for the FFC cables we currently use. I have found vendors providing this service but I cannot find any information on how to lay out gerber files. My application had 3 rigid boards. The "mother" board has 4 layers, with 2 x 2 layer "daughter" boards, and single-layer interconnects which should be flexible. Is there a standard for how to define this sort of design, i.e. which areas are rigid, and which are flexy?

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    \$\begingroup\$ You don't lay out gerber files; gerber files are an output file format from a PCB tool. \$\endgroup\$ – Andy aka Oct 6 at 9:13
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    \$\begingroup\$ Ok, thats a semantic point. I need to generate gerber files which define the flexible/rigid areas. By layout, I mean what information should I put in these typically for a rigid-flexy design? Presumably I need to define extra dimension gerbers to show the outline of the separate rigid and flexible areas? \$\endgroup\$ – bgarrood Oct 6 at 9:21
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    \$\begingroup\$ I would ask the vendor you talked about - if they want the business they'll be only too pleased to assist. \$\endgroup\$ – Andy aka Oct 6 at 9:22
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    \$\begingroup\$ Talk to the PCB vendor. Ask them how they like teh sections delineated. When you're ready to go, have them look at the Gerbers and an overall drawing describing what you want and ask them if they need further calrification. \$\endgroup\$ – Brian Drummond Oct 6 at 11:13
  • \$\begingroup\$ I did ask, but being a Chinese fab house I can't call anyone, and so far they haven't been forthcoming on messages. I was hoping there was a standard, but seems not.. \$\endgroup\$ – bgarrood Oct 6 at 14:36
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Rigid-flex boards are still so outrageously expensive that vendors should be able to work with you to get a mutually acceptable solution.

Last time I did one, I used Altium which has specific features for rigid-flex but I think you could do it simply by laying out a multilayer board with internal (typically) layers designated as FPC. You could demarcate the rigid and flex areas on a mechanical layer just as you would define an outline. Of course the stackup has to be described fully, and any mechanical features such as stiffeners, so either a mechanical layer with a lot of text or a mechanical drawing. I used a proper mechanical drawing with tolerances, showing all the details. The stackup in my case had a core of a polyimide circuit with coverlays in the flex area and FR4 layers on either side in the rigid sections, but there are various possibilities depending on your vendor and budget.

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  • \$\begingroup\$ Thank you. I had asked a generic question (Chinese fab house) and didnt really get anywhere with them yet. I think I'll do as you say, lay it out using mechanical layers to define extra information then once its in for them to look at I can itterate on design info. Thank you! \$\endgroup\$ – bgarrood Oct 6 at 14:35

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