How to use ground stitching and shielding?

Thread Starter

Younes Thabet

Joined Jan 9, 2019
53
Hello guys,

I was wondering when ground stitching 2 ground layers, what kinda pattern and spacing I should follow to place vias? and should I use more vias near components/pads that dissipate more heat?

As for shielding, Is it only used in RF boards or it doesn't matter!!
And if someone can give all cases where stitching and shielding can be used? I will be very thankful.

Thanks,
 

andrewmm

Joined Feb 25, 2011
1,464
Stitching has a few uses as you have indicated,
both very different

Thermal, is of use to move heat. !! They are close together, and at the source of heat. every few mm,

Ground stitching for EMI / EMC, is different.
first you want to ensure that there is no floating copper on top / bottom of the board. All un connected copper needs to be connected to something, normally ground, Much easier on multilayer boards, but always useful,

Then , its normal to ensure you have connected the grounds together every 10mm or so.
That is a bit variable, depends upon frequencies, components, but is a good starting point,

At the end of the day, unless you spend a few thousand on simulation software, its a bit of a best guess.
 

Thread Starter

Younes Thabet

Joined Jan 9, 2019
53
its normal to ensure you have connected the grounds together every 10mm or so. That is a bit variable, depends upon frequencies, components, but is a good starting point, At the end of the day, unless you spend a few thousand on simulation software, its a bit of a best guess.
Then, I could use 10mm spacing between vias as a start, right!!..
So 10mm is just a guess and this kinda things require simulation for better results !!!
could you provide some examples/explanation as for when frequencies and components could affect EMI/EMC!! and how stitching could prevent that?
 

andrewmm

Joined Feb 25, 2011
1,464
Then, I could use 10mm spacing between vias as a start, right!!..
So 10mm is just a guess and this kinda things require simulation for better results !!!
could you provide some examples/explanation as for when frequencies and components could affect EMI/EMC!! and how stitching could prevent that?
yes 10mm is a good start

If you want to start reading up , EMC / EMI a big field,

these guys have IMHO a good course, and some free bits

http://learnemc.com/

and
http://www.compliance-club.com/archive/old_archive/980814.html

https://www.amazon.co.uk/High-Speed-Digital-Design-Semiconductor/dp/0133957241

https://www.oreilly.com/library/view/high-speed-noise-and/9780134580685/
 
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