Author Topic: Adjusting PCB layer thickness for short return path  (Read 1387 times)

0 Members and 2 Guests are viewing this topic.

Offline newtekuserTopic starter

  • Frequent Contributor
  • **
  • Posts: 433
  • Country: us
Adjusting PCB layer thickness for short return path
« on: November 01, 2024, 03:49:25 pm »
I need some input on the values chosen for me by KiCad on my 4 Layer PCB setup. My goal is to bring the ground planes closer to my signal and power planes to have a good short return path. Are the suggested values for thickness good?





 

Online tggzzz

  • Super Contributor
  • ***
  • Posts: 20908
  • Country: gb
  • Numbers, not adjectives
    • Having fun doing more, with less
Re: Adjusting PCB layer thickness for short return path
« Reply #1 on: November 01, 2024, 04:15:37 pm »
I need some input on the values chosen for me by KiCad on my 4 Layer PCB setup. My goal is to bring the ground planes closer to my signal and power planes to have a good short return path. Are the suggested values for thickness good?

Your PCB fabrication house will specify the stackup(s) they can make. Use those figures.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Kurets

  • Contributor
  • Posts: 32
  • Country: se
Re: Adjusting PCB layer thickness for short return path
« Reply #2 on: November 01, 2024, 04:17:26 pm »
Unless you are buying large quantities of PCBs it is unlikely that you can specify the layer stackup freely. Go to your preferred supplier JLPCB, WE Direkt, etc. and look what their standard stackup for a 4-layer board is.

In any case, just having ground/vcc on inner layers will be good enough. The only reason to care about the specific layer separation is if you are trying to do controlled impedance traces for RF or very high speed digital interfaces.
 
The following users thanked this post: newtekuser

Offline newtekuserTopic starter

  • Frequent Contributor
  • **
  • Posts: 433
  • Country: us
Re: Adjusting PCB layer thickness for short return path
« Reply #3 on: November 01, 2024, 05:10:06 pm »
I need some input on the values chosen for me by KiCad on my 4 Layer PCB setup. My goal is to bring the ground planes closer to my signal and power planes to have a good short return path. Are the suggested values for thickness good?

Your PCB fabrication house will specify the stackup(s) they can make. Use those figures.

I know my fabricator (JLC) can manufacture this stackup configuration because they have already produced it for me, but I was wondering if I could improve on it. Based on Kurets' reply I should be good already.
 

Online tggzzz

  • Super Contributor
  • ***
  • Posts: 20908
  • Country: gb
  • Numbers, not adjectives
    • Having fun doing more, with less
Re: Adjusting PCB layer thickness for short return path
« Reply #4 on: November 01, 2024, 07:41:00 pm »
JLC can (apparently; I havn't used  them) do many different thicknesses and stackups.ma

The question is then why one of them wouldn't be satisfactory. If there is an answer to that, then choose another.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline thm_w

  • Super Contributor
  • ***
  • Posts: 7339
  • Country: ca
  • Non-expert
Re: Adjusting PCB layer thickness for short return path
« Reply #5 on: November 01, 2024, 08:57:21 pm »
You choose from the list here: https://jlcpcb.com/impedance
Profile -> Modify profile -> Look and Layout ->  Don't show users' signatures
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf