Homemade boards: NPTH connected on one side only

[Piotr]

@UgaBuga

but on double sided boards you’ll have many small disconnected islands and I need CAD to help me figure out where and how many vias to place.

It looks that you assume that 2 layer board means no solid ground plane.
That sounds surprising to me as since many years all my designs are 2 layer boards with solid ground plane at bottom.
In my case it is possible thanks to:

• using microcontrollers in TQFP case. I went with VCC under TQFP and distribute it through all corners and all VCC pins if needed. So VCC generally don’t disturb other routing.
• powering ICs by ferrite bead. Lefts extra ways to cross signal with VCC line.
• using small resistors (47..100) in digital lines to smooth the slopes.
• if can’t avoid crossing I prefer to use 0R instead of breaking my solid GND.

In typical PCB I need no 0Rs. The highest number of 0Rs used because of routing I remember is 3. It is at PCB I showed its fragment here:

Approaching PCB track routing for a newbie

Positioning for me is the main work in designing PCB. If each element is where it is needed than routing is simple. Till now all my PCBs are 2 layers and all of them have GND plane taking 100% of bottom layer. So except GND I design my PCBs as 1 layer. I use microcontrollers in QFP packages without thermal pad at bottom. This allows me to go with VCC under the microcontroller and go out through all corners and all VCC pins. That way GND and VCC don’t disturb my signal connections. At all digi…

All vias you see there are GND. You can find there something looking like track ended with via but it is also filled zone. When I posted that I thought you can see 2 0Rs there, but there are 3 of them. Right top of microcontroller (over 3 tracks), right bottom of microcontroller (over 2 tracks), and to VC1 track.
So all my vias are used to connect GND pins to GND and to connect GND islands on top to solid GND at bottom. If I were designing home made PCB without metallization I would probably not used GND zone at top at all as it is only a problem to connect all that islands.