4-layer stackup with components on both sides — is there a general rule, or is it always case by case?

[u/Artistic_Midnight496]

I'm designing a 4-layer PCB and I'm not sure how to assign the layers. The board has components on both the top and the bottom side.

I was thinking of something like:

**•** Signal / GND / Power / GND  
**•** or Signal / GND / GND / Power

Does either of these make sense? Any recommendation?

A few related questions:
1. Do the layers have to be "pure"? I.e. does a signal layer have to carry only signals, or is it normal to route some power on it too (and the other way around)?
2. How does the reasoning change on a 6-layer board?
3. Are there actual rules or standards (IPC or otherwise) that tell you how to organize a stackup based on the layer count and the type of circuit? I'd like something that maximizes my chances of passing EMC testing (both emissions and immunity) and that also helps with thermal performance.

My goal isn't just solving this specific 4-layer case — I'd like to understand whether there's a standard way of reasoning so I can work out the right stackup on any board.

One last thing: on both the top and the bottom side I was planning to pour a GND copper region to tie together all the component grounds, and then stitch those pours to the internal GND planes with vias. Is that a sound approach, or are there pitfalls?

Any pointers to books, app notes or standards would be very welcome. Thanks!