Mounting Holes

[KenRogersSBD]

Need assistance/recommendations for working with smaller pin pitch (150 micron) mounting holes for the new nRF52480 chipset.  Our current contract manufacturing supplier for our PCBA has present capability to 200 micron. Are their alternative mountings or adaption strategies that should be considered?

[Andreas]

Hi,

 

Not quite sure what you mean here. If you are referring to the hole size, 0.2mm is probably fine as long as the pad size stays at ~0.3mm (larger will likely cause issues with clearance) and the clearance in internal layers does not increase a whole lot. Changing the distance between via center should not be done, they should be aligned with the pins on the aQFN package.

We have seen designs where the inner-row pins have been routed out between the outer-row pins, through the top/same layer, and not received any reports that this should be an issue. Also, if you only need a couple of the inner-row pins you can probably use dig-bone vias or similar on those few pins. Doing this will likely deteriorate the quality of the chip grounding, so you should make sure the center pad is not increasingly 'isolated' as there are sensitive parts internally that require good grounding to operate properly.

 

Best regards,

Andreas