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Currently I'm working on a PCB that doesn't really need to be 6 layers, but I had to manufacture this project with my other 6 layers. Here is a problem, I have a blank layer; no signal or anything on this plane. Should I leave it empty or make it a GND plane?

My stack is:

Layer 1 ------ Sig / GND

Layer 2 ------ GND Plane

Layer 3 ------ Blank

Layer 4 ------ PWR Plane

Layer 5 ------ GND Plane

Layer 6 ------ Sig / PWR

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  • \$\begingroup\$ Are you doing blind or buried vias? \$\endgroup\$
    – winny
    Jul 15, 2022 at 16:55
  • \$\begingroup\$ blind via or maybe through-hole if i can manage to change some component \$\endgroup\$
    – Settasak
    Jul 15, 2022 at 16:59
  • \$\begingroup\$ Combination of unused inner layer, blind and/or buried vias is a very strange one. Have you considered pwr-gnd-pwr-gnd-pwr-gnd? \$\endgroup\$
    – winny
    Jul 15, 2022 at 17:03
  • \$\begingroup\$ yes theres is still blank plane i mean i can use it for routing some signals but its not really necessary i can still do routing on bot \$\endgroup\$
    – Settasak
    Jul 15, 2022 at 17:09
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    \$\begingroup\$ In what way you want suggestions to use it? Fill with GND or VCC, or draw a neat picure as an easter egg? \$\endgroup\$
    – Justme
    Jul 15, 2022 at 18:00

1 Answer 1

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That's a huge waste.

  1. Make it a signal plane. I'm sure you will find a use for it while you are routing layers 1 and 6.
  2. Or if you have more than one widespread voltage on your PCB make it a power plane for that voltage.
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  • \$\begingroup\$ yep but if i want to use that for signal i need blind via its will cost more than just waste it btw adjacent pwr plane is alright? \$\endgroup\$
    – Settasak
    Jul 15, 2022 at 16:55
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    \$\begingroup\$ @Settasak Why would you need blind vias to access an inner layer? You already need thru vias to go between top/bottom signal layers. \$\endgroup\$ Jul 15, 2022 at 16:59
  • \$\begingroup\$ blind via to GND plane and on bottom layer is just some regulator that going into layer 4 so now i dont have any thru via \$\endgroup\$
    – Settasak
    Jul 15, 2022 at 17:02
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    \$\begingroup\$ @Settasak So don't use blind vias. Thru-vias don't need to connect to every plane they put a hole through. If they did you would never be able to connect signals between your signal layers together if power/ground planes were in between. \$\endgroup\$
    – DKNguyen
    Jul 15, 2022 at 17:40
  • \$\begingroup\$ Sound like this will be an expensive PCB without good reason. \$\endgroup\$
    – winny
    Jul 15, 2022 at 17:56

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