In article ,
"robb" wrote:

Is there an operational/safety benefit to flooding empty space
with ground copper ?

Operationally it can reduce noise pickup and/or radiation. It does
nothing much for safety.

and how does one choose the value for the capacitors between
ground and power ? as that is a bit out my scope

A: what have you got in the junk box - use it.

B: 0.1uF or 0.22 uF are often good values if parts need to be bought.
Place as close to the PLCC power/ground inputs as possible.

When you get into high-speed stuff, I'll defer to the folks that are
doing that - there have been some spirited discussions about bypassing
in the past few months, with adherents of various rules-of-thumb
valiantly proposing myriad "One True Path" options. I was personally
brought up in the 10uF and 0.1uF in parallel rule-of-thumb, but I know
it's a rule-of-thumb, not a religion or "One True Path" or even a set of
values modeled to provide the best possible performance.

For most digital stuff, a 0.1uF from each chip's power to its ground, as
close to the chip as possible, is another rule-of-thumb (for a while you
could get DIP chip sockets which had those built-in for default
power/ground locations for logic - I don't know if they are still
available, less of an issue with SMT parts and the lack of reliability
that sockets provide in the long run. SMT offers the ability to park the
capacitor on the backside of the board right under the chip, which was
"not done" when through hole components were only mounted on one side of
the board, so they could be wave soldered.)

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