nRF52833 aQFN package

[MBarBurtonems]

Hi, 

We are having issues with this part bridging on our via-in-pads.  We are using 2oz finished outer layer copper. 

Do you have any footprint recommendations for 2oz copper? 

We are thinking of making the via-in-pads solder mask defined. Would it be better to only make the via in pads solder mask defined or to make all of the pads solder mask defined?

[Asbjørn]

Hello,

Solder mask would be recommended for all pads. The small spacing between them is challenging and if you are implementing on some we would recommend to implementing it on all. 

How many units did you assemble and were they all faulty? Any particular set of pins you've had more issues with than others?

Best regards

Asbjørn

[MBarBurtonems]

We usually make several thousand per job and we have about 15% fallout due to bridges. All of the bridges happen on our via-in-pads, mostly on the inner rows of pins.  The via-in-pads are 15mil diameter and plugged, the solder mask defined opening is 12mils, our paste aperture is 11.8mils.