aQFN package footprint, IPC

[Mr.Martin]

Hi,

Looking at the footprint you supply for the aQFN73 package (I have looked at the one supplied for nRF52840), I see that the pad have a size = 0.275mm.
If IPC-7351 is followed, and the Maximum Material Condition (MMC) is used for the pads, the resulting pad size = 0.2mm (using the supplied nominal ball diameter in your datasheet).
Have you encountered problems using the IPC standard with your package and thus used a ~25% larger pad size? Maybe there are other reasons?

Best Regards

Martin

[ketiljo]

The footprint was made based on an appnote from ASE, the company that makes the aQFN packet:aQFN application note and aQFN,LGA process.pdf

Why they deviate from IPC, I don't know, but there haven't been any production problems, at least for the DKs.

[Mr.Martin]

Ok!
Thanks for the reply