SMT Electrolytic Footprints

Hi, I am having trouble understanding the SMT electrolytic caps footprints. Here is an example from the KiCAD library that is “6.3x3.9”.

Footprint|637x500

This page indicates that the numbers are the X and Y dimensions of the cap package.

By moving the cursor over the footprint I can see that the 6.3 appears to be the diameter of the can. I can’t see what the 3.9 relates to. It doesn’t seem to be the Y dimension. What is it?

Thanks!

It is the height of the can.
Although the size of the 6.3mm footprints is (nearly) the same, they have different 3D models attached for the different heights.

Here I’ve put a few in the foreground, from 3mm to 9.9mm (all 6.3mm diameter).

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Great, that makes more sense than the naming convention - thanks!

The naming convention changes a bit, depending on what sort of dimensions make the most sense for each particular group of footprints.

They are probably written in the KLC but the KLC follows sensible rules so it’s usually quite easy to guess.

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