Setting All Pad Sizes

If you would like to change the pad sizes for a board layout that you are going to etch, here is a brief description of how to do that. You must open your layout in the board layout editor to follow this procedure. Type “drc” into the command line or select the drc button on the bottom left tool bar and Eagle will open the Design Rule Check dialog window.

In the picture below, we have selected the “Restring” tab in the Design Rule Check dialog window. The “Max” entry for vias on the “outer” layers of the board is highlighted.

To specify the pad size, set the “Min” and “Max” values. You can ingnore the “%” column. In the pictur, I have chosen 25mil for “Bottom” layer pads and “Outer” layer vias.  Typically, these are the only visible pads in one of my PCB layouts.

You can click on the “Apply” button and see the effect on your layout without closing this window. When you are done, just close the DRC window.

If the pad size set by the library is greater than what you specify in this dialog, then your entries will have no effect.

Here is some of what the Eagle help file says about Restring:

The Restring tab defines the width of the copper ring that has to remain after the pad or via has been drilled. Values are defined in percent of the drill diameter and there can be an absolute minimum and maximum limit. Restrings for pads can be different for the top, bottom and inner layers, while for vias they can be different for the outer and inner layers.

If the actual diameter of a pad (as defined in the library) or a via would result in a larger restring, that value will be used in the outer layers.