Nested Copper Pour?

[frvesey]

HELP! How do I create a copper pour within in a copper pour?

[Tom]

Very carefully.

Is it Copper Pour or a Split/Mixed Plane?

[frvesey]

Just a copper pour.

[Tom]

The Outer Copper Pour has to be drawn as a ploygon with 10 lines that leave a hole. See the picture below.

[Tom Frayda]

Umm, why not just a copper cut-out around the inner pour that you just select shape with the outer pour and then RMB combine , Tom?

[Tom]

Because the two copper netnames need to be differnet.

[Tom Frayda]

So? It still works.

[frvesey]

Here's what I've done so far. We are trying to create 4 different power connections using copper pour. These 4 pours will be surrounded by a copper pour, that will be a ground sheild.

Here's what happens. After using the "PO" connection all 5 pours (Powers and Ground sheild) flood wonderfully. I type the "PO" command again, and reflood. Some of the inner pours do not flood.

[Tom]

Tom,

Yes, pouring one copper pour square with one netname and a keepout to hollow out the center copper creates two copper islands, both with the same netname.

Unfortunately the inside Copper Pour needs to be a separate netname. How do you do that?

You need to attach a picture of your solution, because my picture is the way we've been doing it for the past 10 years and if you have a new method that works I'm really interested in knowing about it.

[Tom]

Francis,

Here is a copper pour solution with the outer edge GND and 5 individual copper pours inside it. Works for me every time.

[Tom Frayda]

Am I missing something?

Create the outside pour outline and assign the desired net to it. Create the inside copper pour and assign the desired net to it.

Create a copper cut-out around the inner pour. Select shape the copper cut-out and the OUTER copper pour and RMB=>Combine.

A Flood All will flood both pours.

Keep in mind though, a copper pour associated to a net will not fill if there is no connection to the net to which it is associated within in its boundaries (ie: a via or thru-hole).

S/M Planes work the same way, only they created the cut and combine it automatically if you create the planes from the outside and work inward.

[Tom Frayda]

See attached asc file for crude example. Note that the top side ground pour would not fill if it were not for the one free via connecting it to the bottom ground pour.

[Tom]

Tom,

You're absolutely correct. If the outside board edge perimeter needs to be grounded and you need to copper pour in the center of it, you can use "Regular Copper" and flood the entire board and then insert a Copper Cutout in the center of the board that is Combined with the Regular Copper you can then proceed to Copper Pour on the inside of that.

We have used this technique on several designs in the past year and I totally spaced on this technique.

There is one great advantage to this if your board outline is curvy or has indents and chamfers, you can use the scale command and copy it and convert it to copper all in one move.

[Tom Frayda]

Yep. I was pretty certain that you were involved in some threads related to this subject back when you frequented the PADS listserver, so I was surprised that you didn't raise this idea as a solution.

Incidentally, another great way of dealing with creating copper pour for irregularly-shaped boards is to temporarily change the layers to S/M, set your S/M Plane Auto Separate Gap Preferences to (desired board edge clearance)-(0.5)*(board outline line width), select the board outline, RMB=>Create Plane Area. You can then just change the layers back to No Plane and the S/M Plane becomes copper pour. I like your solution with the Scale feature too.

[Tom]

Here's a design that I did a couple of months ago where I used the technique of flooding the entire board with "Regular Copper" and then carved out a "Copper Cutout" and combined the two together. I also had to add & combine two circle Copper Cutouts for two Non-Plated Holes in the corners.

This is just the opposite of having an irregular board outline. It's the Cutout that had to be customized.

Inside the copper board edge the entire layer is copper poured (but I turned it off to illustrate the Chassis Ground Board Edge). I can run all DRC checks and get "No Errors Found".

One of the great things about Regular Copper is that you do not need any vias for the copper to show up and it does not require re-flooding every time.

This technology is great! I highly recommend it for all PCB designs that require a Chassis Ground Board Outline Perimeter. Thanks Tom Frayda for shaking me up.