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Platform forum

JohnsonMiller , 03-26-2022, 03:56 AM

In my design with 0.4mm BGA, I have set solder mak opening as 0.0, which means the opening is the same as the PAD or no air-gap; now the manufacturer is asking for more air-gap and asks for solder mak opening bigger than the PAD! It looks like my original thought that the same opening as the PAD will help was wrong, now wondering what is the technical reason for the bigger opening?

WhoKnewKnows , 03-26-2022, 07:32 AM

The main reason the solder mask expansion setting exists is to help compensate for misalignment between solder mask opening and copper features. Also, see the attached link to Google solder mask defined pads vs copper defined pads.

qdrives , 03-26-2022, 04:59 PM

SMD for BGA <= 0.4mm: https://youtu.be/cMxXea16Hxc?t=4795

robertferanec , 04-04-2022, 03:08 AM

I would recommend to watch the video what @qdrives suggested (I was going to post the same one)