Definitions of poured, non-poured, hatch and flood?

[MrPink]

Howdy again!

I'm confused about copper definitions. What's the difference between fixed (or non-poured) and poured copper? What's the difference between flooding and hatching? And most specifically, under what circumstances would I use the corresponding processes?

I ask because I need to draw what I would call a "noise plane" around an SMD device and its pins and also around the decoupling caps that serve it. Knowing which method would be correct to use would be most helpful.

How come there's no "PCB Design for Dummies" in that series of books? <big grin> Is there any decent sort of text that defines standards, practices, terminology, board house bugaboos to avoid and such that would help someone like me who doesn't have a design mentor to help? I can't seem to find much out there. Any suggestons?

Thanks!

-Pink

[Tom]

There are basically two types of Copper Pour.

One is just a simple closed polygon that you can put on any "Positive" layer (Not a CAM Plane Layer) that will flood around the pins and traces that are not in the net assigned to that copper. It will also flood over traces and thermal into vias or pads, but that is under your control (flood over or thermal and thermal size.) There are limitations to this type of Copper Pour and one of them is that it is very difficult to Pour over another pour or to have an "Island" in the middle of an existing Copper Pour. Also, this Copper Pour does not allow you to do a Plane DRC check but it does perform a Connectivity DRC check.

The other Copper Pour is a Split Mixed Plane that requires you to modify the Setup/Layer Definitions and assign a specific layer to a group of Split/Mixed nets. The Split/Mixed Copper Pour is more powerful and can have "Islands" in the middle of your design. This also gives a "Plane DRC" check. You can also insert a Split/Mixed Plane by selecting your "Board Outline" and "Auto-Generate" the Copper Pour data.

The one thing that they both have in common is that they both have an edge (Outline) and a Hatch (Copper Fill).

When you Flood a Copper Pour you totally regenerate it and all the "Isolated Pours" that come with it. You have to use "Flood" every time you change the boundries of the Copper Pour Edge.

When you exit from a PCB layout, PowerPCB compresses the Copper Pour Hatch so that when you open your design, the Hatch area is still compressed. To regenerate the Copper Hatch you use "Tools/Pour Manager/Hatch" and your Copper Hatch will be visible again. You only use Hatch to regenerate the existing "Filled Copper Area" inside the Copper Pour Outline. You use Flood to recreate the Hatched area.

This is more difficult to write than it is to explain. Let me know if you still don't get it.

[randychase]

Just to add to this:

Fixed copper is the element in a polygon that becomes copper on a board. It can have signal net intelligence and be checked. That makes it different that a 2D line. Also it can be solid even though it's really a hatchwork of copper lines. You define the line width and spacing. Line width is set on the copper element. Spacing is part of your preferences. You define the outline of the element, and using the grid you set in your preferences and the width you are working with, it creates a solid over everything.

2D lines don't create a solid internally. You can draw a solid with 2D lines using a lot of lines though. 2D lines are not checked for net rules violation, so great care must be used when using 2D lines on electrical layers. I think it's a bad idea myself.

Copper Pour is the same as fixed copper, except it intelligently pours around other electrical elements that don't have the same net name. You define the outline, and it fills in the copper, but misses the traces and pads and other copper elements.

The command to FLOOD is the act of telling PowerPCB to create this internal hatched area. Calculate clearances and voids. Calculate the thermal connections and spokes. This is a HATCH, but it is generated intelligently. When you move anything electrical on that layer, or change the flooded copper in any way, you want to always use the FLOOD command.

FLOOD uses HATCHING. So when would you use the HATCH command? When you did not change the copper pour, but it's no longer hatched. PowerPCB does not save all the hatched copper when you exit, though it saves the parameters of the flood. To recreate the copper inside without having PowerPCB calculate clearances and such, you could just tell it to HATCH ALL.

Basically.....very basically...if you are making a new Copper Pour area, use FLOOD. And if you make any changes, use FLOOD. And if you pull up an existing file and want to see the copper plane again or create new CAM files, you can either use FLOOD or use HATCH.

Advanced user note. You can tweak things and fool the system by flooding and then changing something. For example, if flooding is not giving you enough clearance around a mounting hole, increase the size of the pad, then flood, then decrease the size of the pad. Now you have a lot more clearance without dealing with this minimum copper clearance to pad which may work for something else, but not as well on a large pad..or a very small pad on a drill but not plated thru hole.

When you bring the board back up again, you would intentionally use HATCH instead of FLOOD since you don't want the system to regenerate and calculate new clearances. You want it to stay "fooled."

I hope that helps!

[MrPink]

You guys are fantastic!

This makes so much more sense, now. Thank you!

Got another question about something totally different now, but I'm going to start a new thread to discuss it.

-Pink