gaussmarkov: diy fx

Next I am going to edit/change some of the properties of this ground pour. All of these properties can be changed with mouse clicks, but showing that in a sequence of images is time consuming. So I am just going to give the equivalent keyboard commands and hope that you can figure out the mouse versions if that is what you prefer to use.

First, I am going to change the distance that the ground pour keeps from everything else. Enter into the command line

change isolate 24

or just “ch iso 24″ and then click on the edge of the ground pour. The result looks like this

so that all the gaps are narrower. At the beginning of this tutorial, I typed “ch iso 40″ so that I have reduced the ISOLATE parameter form 40mils to 24mils. That is what sets the distance between the ground pour and everything that is not grounded.

Second, I am going to change where the ground pour appears. Enter into the command line

change orphan on

or just “ch orph on”, click on the edge of the ground pour, and you will see this:

This caused islands of ground pour to appear between C2 and C3 and between R3 and R5. These are called orphans by Eagle and they are not connected to the original ground pour. You will see that in my layouts I leave the ORPHANS parameter off and that is the value that I set at the beginning of the tutorial.

If you type

change width 10

and click on the edge of the polygon next then you are changing the 40mil width that I set at the beginning of the tutorial to only 10mils. This changes the image above to

so that the pour appears in narrower gaps between traces.

One more parameter change: enter “change thermals on” and click an edge of the polygon. This time you may not notice a difference at first. Here is an enlargement of the lower left-hand corner:

What you see is that the pads are partially isolated from the rest of the ground pour. The thick connections are the 40mil traces that were there before putting in the ground pour. The thinner connections are 10mil traces (because that is the WIDTH parameter we chose above) created by the polygon. These are called THERMALS because they prevent the ground pour from acting like a heat sink when one is soldering connections to them.

I am almost finished writing this tutoral. I need to make a few closing remarks comparing the DELETE and RIP commands, the POLYGON_RATSNEST paramer, and how to make sure that VIAS have thermals just like PADS.  I will probably do this sometime over the weekend.