Also, it seems to me, that there's a big discrepancy. Many people tell, that they never had used even a double sided PCB with their microcontroller applications, only one sided ones. Others tell that they only use four layer boards. What's right, then? I think, double sided PCB with solid ground plane can cover a very wide range of applications. And it's not at all old fashioned to use them!!
Yes, I only use 4 layer boards. Does all my applications need that? right now yes, I am running 50MHz oneclockers and things are flying around pretty fast.
On the side I am making a little circuit for a friend with a LPC running at 7.xxx MHz and, that would probably work with two layers, but why the hassle with grooves in the ground plane where traces must be on the backside and difficulty finding room for heavy Vcc traces on the signal side.
The end result of trying to make it two layer end up with a larger board and now, in addition to a holy ground plane, you have longer traces.


And, what kind of pills shall an engineer take, whose product didn't pass the CE testings, allthough having had used a four layer board?
Aspirin as well, but failing after having done right hurt a whole lot less than failing after having done wrong.

Erik