Creating custom pads in Eagle library

[rrrremus]

Hello. I am using Eagle 5.6 and have encountered what i believe to be a limitation of the software. I wanted to create a footprint for a X2SON package but as you can see the pads have one edge cut at 45 degrees angle. I see no possibility to recreate this shape as a SMD pad in the Eagle editor. I have also tried to draw the pad out of a Polygon, but i cannot get the drawn polygon to be assigned to a net or pin number. Any ideas? Thanks

 

[dchisholm]

Wow. Who thought up a package with THAT footprint? What device comes in that package?

I can't offer tangible help, only some brainstorming ideas. (In fact, I have never even used Eagle, but have at least a few hours on several other layout programs.) Please forgive me if you have already investigated, and discarded, these ideas:

• I have seen programs that allow you to define a custom polygon for a pad shape. I vaguely recall trying to use the feature once, but abandoned the attempt. As I recall, I solved the problem by starting with one of the standard pad shapes then overlaid some lines (short traces) to create an approximation to the desired shape. I probably had to make a lot of manual edits in the solder mask and paste stencil layers. As long as the lines and pad were touching (or slightly overlaid), the program correctly interpreted them as electrically connected.
• A similar approach, but thinking somewhat "backwards": start with a standard pad that covers the entire area of interest, then use cutouts or keepouts to create the desired shape by "removing" the copper where you do NOT want it to be. (Instead of defining where you WANT the copper to be.)
• Make sure your polygon pad was originally drawn, and subsequently placed, on a "signal layer" (or "copper layer", or "conductor layer", or whatever your software calls it). That's probably a prerequisite for assigning it to a net.
• If your software differentiates between "outline polygons" and "filled polygons", make sure you use the correct type.
• By any chance, does the component vendor offer predefined CAD models for this part, in Eagle format? It seems like many manufacturers are doing that these days, at least for the big-name (and big-money) PWB layout programs. Even if it's not specifically mentioned, ask your sales reps about it - they may know another customer who is using the part, designs his boards in Eagle, and is willing to share the padstack file.

Dale

 

[Tubelab_com]

Who thought up a package with THAT footprint? What device comes in that package?

TI

Tiny little LDO's and logic level translators that are used in cell phones.