Hey Guys, It's a been a while since we had a bypass capacitor religious war, so I thought I'd stir things up a bit! Seriously, I've been reading about X2Y capacitors, and a search of the newsgroup revealed that these very interesting parts have only been mentioned once or twice in passing. (By Austin, natch!)
Check out :-Where they ask you to register for :-
Steve Weir does a great job of showing why X2Y caps give you more bang for your buck. As these parts have exceptionally low inductance, they can substantially reduce the number of capacitors AND vias you need, and they quote that :- "Can replace from three to six+ regular caps depending on via and plane geometries" "Vias at $0.005/hole / $0.01 / capacitor typical, often COST MORE than the capacitors they connect!"
Here's another interesting article:-
They recommend using small 'puddles' of copper to connect all the bypass elements together so you can use fewer capacitors but keep the same bypass network performance.
Check outfor more articles.
AFAICS, the main drawback is that X2Y caps are available in a range of values. This means nutters will use several different values in their bypass networks to create 'resonances' and the like. :-)
Anyway, I hope this is of interest, Syms.