PCBA Assembly NRF52840-QIAA

[Eliran Amar]

Hi,

During automatic assembly of the NRF52840-QIAA

We have found after Xray that we have air gaps surrounding ground pad vias - see attached images below.

I am trying to understand what is the root cause of this phenomenon.

Appreciate any idea or relevant experience with this issue.

Thanks,

Eliran.

[JONATHAN LL]

Hi,

We do have a app note on land pad area and includes notes on vias, it looks like most of the solder tin has traveled down the via not leaving enough solder on the surface, one way to circumvent this issue is to use capped or filled vias. 

Here are some links:
PCB Design Guidelines - VIA FILLING - Eurocircuits Eurocircuits 

Via hole plugging - what is it and when can it be used - NCAB Group 


So the size of the past mask needs to be adjusted to account for this behavior. 

Regards,
Jonathan