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Controlled impedance traces specification for manufacturer

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  • Controlled impedance traces specification for manufacturer

    Hello to everyone,

    I am confused about how to specify to the manufacturer which traces should be controlled impedance. The way how I did the previous controlled impedance designs is to rely to the manufacturer stack up and apply the proper geometry to the specific traces. I also put stack up table in a separate layer - manufacturing notes (learned from Robert). However, some manufacturers (cheap one) insist on doing it on its own. I suppose they doing it by modifying the gerber file and adopting the correct trace geometry. But, how it actually works? How can I tell them, I need that and that trace to be controlled impedance? Does it work like that I described?

    Thank you in advance.
    Last edited by IgorStojanovic; 09-27-2018, 04:22 AM.

  • #2
    You can set the impedance controlled tracks to a specific width and describe this in the manufacturer notes. Then the manufacturer will know that those are the desired tracks that need to be modified.

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    • #3
      Yes, it makes sense. Thank you.

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      • #4
        We always add screenshots with highlighted nets. It looks something like this (this is file called DIFF100-L3):

        Click image for larger version

Name:	DIFF100-L3.jpg
Views:	18
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ID:	8860

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        • #5
          That is very useful. Thank you Robert.

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          • #6
            I Use mechanical layers and use text with reference info, because sometimes i make cutouts in the internal ref planes to change the impedance.. (the world of 75Ohms video sucks in that way)

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