Editing footprint solder mask in Eagle

[kikib]

Hi all, I'm new to Eagle CAD and still learning a lot. I really like its advanced high-speed features (differential pair routing, length matching, miter etc) which are great for complex designs. 

I'm trying to create a footprint with custom solder mask and paste mask. Basically it's a 1mm diameter fiducial mark that has a 3mm dia. solder mask and likewise a 3mm dia. paste mask.

Do I somehow edit the default ones or is it done another way?

[kizzap]

You can do it both ways, tstop or bstop (top or bottom) are your soldermask pullback layers. If you were planning on using this pad on a lot of boards, I would suggest making a custom library for it.

-kizzap

[kikib]

I have made a custom library for it. In the library I am editing the 'package' (name for footprint in Eagle) which is where I am trying to edit the solder and paste mask of the fiducial.

I can't see how to adjust the default masks in there. Am I supposed to just draw a circle around the default masks to effectively extend the masks?

[kizzap]

To get a solid tstop pad, draw your circle, but at a width of zero. Should show you a solid circle

[kikib]

Yep that circle trick does the job perfectly, thanks a lot!

Every day I learn something new in Eagle.

[LukeW]

When you draw a surface mount pad in a custom Eagle library package, it has a solder paste stencil aperture (aka "cream" layer) and a solder mask aperture (aka "stop" layer) automatically generated with it.

I think these can dynamically change when the component is in your board layout, based on DRC settings.

To turn off the "automatic" generation of these layers, change the "Cream" and/or "Stop" properties of that copper pad in the package, and turn them from "on" to "off". Now you've got just a copper pad, no soldermask or paste layer. Now you can use the draw-rectangle tool, on either the stop layer or cream layer, to manually draw a fixed rectangle around the pad for that layer, with exactly the customised dimensions that you control.