[sdiy] SMD experiences

[David G Dixon]

> I have yet to do a 4-layer board, but it's really no big 
> deal, as I just have two extra planes on which I can route 
> signals (but not place
> components!) - all the clever stuff gets sorted out at the 
> fab :-)  I came close to going 4-layer for my digital 
> ADSR/LFO board, as I was finding that power traces kept 
> getting in the way.  But price is double for the extra 
> layers. The MIDI router/processor I'm designing will likely 
> go to 4 layers.

I would say, just watch out for capacitive and inductive effects,
particularly with long high-impedance traces running in parallel with signal
traces.  With 4-layer boards, layer-to-layer bleedthrough may become and
issue if traces are parallel.