Electronics > KiCad

QFN pad confusion for F.Paste selection

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newtekuser:
I have this footprint for a MP8765 buck converter IC (came from Ultra Librarian) where pads 8, 9 have the F.Paste on, but not pads 15, 16, all of these belong to the same net. There's also a polygon/filled shape below pad 15 with F.Paste turned on.
Shouldn't all these pads have F.Paste turned on, and what's the deal with the "extra polygon" with F.Paste turned on?

I have this stencil in production and they're not sure how I want this polygon to be cut (f.paste or solder paste). I think it has to be cut on the f.paste. But now I start to wonder about pads 15, 16 as well.

Doctorandus_P:
F.Paste is KiCad's name for the solder paste layer for the front side of the PCB, so I'm not sure what the question is.

I have not looked at the datasheet of your MP8765. It is relatively common that the footprints for IC's get modified in some way.

I also would not trust a footprint from UltraLibrarian (nor SnapEDA, nor Samacsys nor PCB Libraries or any of the other "footprint collector sites". With big center pads, the cutout in the solder stencil is often much smaller then the exposed pad or the copper on the PCB. If it was the same size, there would be far too much solder on the pad, and the IC would float on the center pad, without the pads on the circumference getting soldered.

newtekuser:

--- Quote from: Doctorandus_P on November 05, 2024, 11:20:52 pm ---F.Paste is KiCad's name for the solder paste layer for the front side of the PCB, so I'm not sure what the question is.

I have not looked at the datasheet of your MP8765. It is relatively common that the footprints for IC's get modified in some way.

I also would not trust a footprint from UltraLibrarian (nor SnapEDA, nor Samacsys nor PCB Libraries or any of the other "footprint collector sites". With big center pads, the cutout in the solder stencil is often much smaller then the exposed pad or the copper on the PCB. If it was the same size, there would be far too much solder on the pad, and the IC would float on the center pad, without the pads on the circumference getting soldered.

--- End quote ---

Is there a better place to source these footprints, or is the best practice to DIY them?

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