# Eagle - Custom pad shape for SMT inductor

I'm trying to make the following footprint in Eagle for an SMT inductor:

I understood how to make D-shape pads and similar, but this is driving me nuts: my idea was to enclose a pad into a polygon with 6 vertices, so I could bend the lower central segment into the arc with the radius shown above in the figure.

I've tried to do this in many ways but I can't figure out how. I've also thought about importing some dxf or svg, in order to draw it with a more drawing-friendly software like Inkscape. Any ideas on how to obtain this shape?

• I don't know if its possible in a part library, but on a board, I would draw two rectanglar polygons in the copper layer, and a central circle in the restrict layer. On ratsnest, the circle will "cut out" a round shape from the polygons. – sweber Jan 9 at 19:11
• web.mit.edu/xavid/arch/i386_rhel4/help/27.htm – Scott Seidman Jan 9 at 19:16
• @sweber unfortunately the rastnest isn't available when designing a footprint – C.Slade Jan 9 at 19:56
• @ScottSeidman I tried with the "arc" function and then using some wires to form the polygon, but then I don't know how to fill the area delimited by the arc and wires – C.Slade Jan 9 at 19:58
• element14.com/community/thread/59540/l/… – Scott Seidman Jan 10 at 0:55

Ok, found a way to do it. I post it here as a possible solution for anybody else who will incur in a similar problem.

I've used the polygon tool in a different way. I took the points shown in the image below as the vertices:

Then, I created the polygon with all straight lines. By editing the "curve" parameter of the segments AB and AC and by modifying slightly the position of the points A, B and C, I finally got the shape I wanted, using a circle in the tDocu layer as a reference. Here is the result and I'm pretty happy with it: not 100% precise, but it will do (for reference, tPlace tracks are 4 mils wide).

• Good solution. Bear in mind you also need place holes in the solder mask (tStop) otherwise this will be covered at manufacture. You should also place tCream if you intend to get a solder stencil made. – awjlogan Jan 11 at 16:35
• Of course, in the picture they're barely visible but tStop and tCream layers are in place, drawn with the same method used for the top layer. – C.Slade Jan 11 at 18:42