DFN FET footprint creation

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1

Hi, I required a DFN footprint for FET AONR21307. I found one on SnapEDA and downloaded it as an Eagle library. Sadly (after local library gripes were fixed) this footprint fell fowl of the DRC once loaded on the board. It could not merge the simple pad and a layer of top copper of the actual complex pad shape.
I went back to the library editor and created a custom pad of the correct shape (all 29 coords !!).
The library editor objects that there are no solder paste areas defined for this pad. (see below)

The SMT pad has no solder paste enabled, which is unusual since without solder paste the pad cannot be reflow soldered. Only use this if there’s no lead to be soldered on that pad, or if you have drawn a manual solder paste area…

Upon deeper investigation, by pulling the layers apart I could determine that there are a number of them defined, one large one for the main body and 6 separate ones for the projecting 4 pins and 2 side tangs. (see screen images).

I could just ignore the error by accepting it, but I will only if its actually OK once I make the gerbers.

Any advice gratefully received.

DFN 8 FET footprint-seperated layers
DFN 8 FET footprint-seperated layers734×460 34.8 KB

2

Hi,

This is a property of the pad, which is enabled by default but probably it was disabled in the Eagle library because Eagle does not support this feature. Just enable it in the pad properties:

image
image592×408 34.5 KB

Then you can (and should) delete all the custom solder paste polygons.

For such rather complex pads I’d suggest to verify in the 3D footprint viewer if everything looks correct.

3

Thanks for the reply. This has fixed the warning in the editor. Now I can move ahead.

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