I have noticed that the footprint TO-252-2 from Package_TO_SOT_SMD has changed from KiCad V8 to KiCad V9. Before, it was defined using pads, now using SMD apertures.
Now, if I select a paste relative clearance in Board Setup to generate my stencil, several of the apertures in F.Paste are not reduced as intended. Then, the paste is applied to the edge of the pad. Is something wrong with the footprint or is the new standard?
KiCad V8 without clearance _________KiCad V8 with clearance
The V9 footprint is made with the correct technique. Thermal pad aperture sizes should not depend on the shrinking factor. The apertures look a bit large, but according to the datasheet they are only 0.05 mm too large (in length and width).
The official KiCad footprints which are made automatically with scripts follow some general standards, but for individually contributed footprints datasheet values can be used. So, the answer to your question is “neither”. The older footprint behaved in a wrong way because it used copper pads for thermal paste apertures.
