AVR Freaks

With copper pours, you need to include "thermal reliefs" between the pad and the pour. Otherwise, it can be very hard to solder.

One ground pour is very common. I do it on almost all of my boards. There are, however, a few cases, such as switch mode power supplies, where you want to keep the very high, and very fast, currents out of the general ground plane. Designers add slots and various things to confine those currents to limited areas. You can also get undesirable cross-talk in RF and video circuits due to shared ground planes - again, slots and various other things, can be used to provide isolation between different regions of a common ground.

Power pour is less common, though not rare. I tend to use heavier traces for power, even if not needed on the basis of current levels. Another factor, though, is that when you DO use a back-side ground pour, the tendency is to put most of the traces on the top side, leaving less room for a pour.

There are some economic factors, also. If you are using etched copper, a pour removes less metal and less of the original board material goes "down the drain" (though it had better not be going down someone's sewer drain). On the other hand, additive copper can cost more as more copper area is deposited. Thus, there may be cases where copper pour might cost you less and others where it might cost you more.

Jim

No, you have to add a polygon describing the outer edge of the pour in Eagle. Then, you name the polygon to be a member of the ground net. Eagle automatically does generate the "thermal reliefs" between ground pads and the ground pour so you do not have to do that, yourself.

It is almost painless, but not automatic.

Jim