Copper pour advice.

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I'm finishing up a double sided PCB, is it a good idea to copper pour both sides and connect one to GND and one to Vcc, or is there a better option?
All advice gratefully received, as I'm a rookie at PCB routing.

John

Four legs good, two legs bad, three legs stable.

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What you are proposing is often done. Also ground on both sides is common.

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Are you planing to etch the board yourself or use a board house to do it?

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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

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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I noticed that this copper pour thing is something fairly recent. Not that long ago no one seemed to bother.

Many hobbyist use Eagle, I guess it does this by default during post-processing or so?

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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

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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dksmall wrote:
Are you planing to etch the board yourself or use a board house to do it?

Board house.

Four legs good, two legs bad, three legs stable.

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

Yep, Diptrace does that for you.

Four legs good, two legs bad, three legs stable.

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More copper reduces board warping (especially for "large" boards) and improves thermal conductivity.

"Dare to be naïve." - Buckminster Fuller

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My PCB is small enough to fit in an "Altoid's smalls" tin, easily, and consumes about 20mW at the peak of its activity, but thanks for the advice.

John

Four legs good, two legs bad, three legs stable.

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Wow, I've never made anything for that tiny box!

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

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It's not made for that tiny box!
I was simply using it as a metric.

Four legs good, two legs bad, three legs stable.