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I'm using some transistors in SOT-23 packages, designing a board in KiCAD 7.

  • NXP's recommended footprint has pads 0.6 x 0.7 mm. Datasheet
  • Vishay's "recommended minimum" has pads 0.559 x 0.725 mm Datasheet
  • KiCAD's pads are much bigger 0.6 x 1.475 mm (Package TO SOT SMD:SOT-23)
  • KiCAD's "handsolder" variant even bigger: 0.8 x 1.9 mm (Package TO SOT SMD:SOT-23_Handsoldering)

What advantages are there to such long pads? Can I simply shorten them to, say, 0.8 mm long?

I can only see thermal advantage; as a disadvantage it's making my tracking a little difficult, as I'd like to send a signal up from pin 2 between 1 and 3.

enter image description here
From KiCAD 7.0.6 footprint

enter image description here
From NXP SOT-23 packaging information

jonathanjo
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    Easier to solder (by hand) and sure; you can reproduce entirely what a data sheet recommends. – Andy aka Aug 30 '23 at 18:38
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    Is that one of the "handsolder" variants? Many of the footprints have a larger, easier-to-solder version. – rdtsc Aug 30 '23 at 19:21
  • @rdtsc No, it was the "plain" variant. Updated question with dimension of handsolder variant, clarified footprint names. – jonathanjo Aug 30 '23 at 19:54
  • I bet KiCAD is generalizing for *any* SOT-23 device, while this part is "small" for a SOT-23. I'd say to take that footprint, copy it into your own private library, and trim it down closer to the recommended size. I've made it a habit to have parts onhand, then print a 1:1 paper output of the board with all footprints on it, then physically match each component to the footprint, all before sending for board fab. Invariably, a few are found which need adjustment - sometimes minor, sometimes major. – rdtsc Aug 31 '23 at 11:46
  • @rdtsc Thanks for good advice. I'm in the habit of library-per-project in any case, so that no library updates change anything. – jonathanjo Aug 31 '23 at 11:50

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