nRf52832 CIAA reference layout

[Francesco_M]

Hello,

I noted that in the reference layout for nRF52832 CIAA with DC/DC converter there are VIP (Via-In-Pad) and blind via underneath the WLCSP package. I would like to know why you used a blind via from top layer to inner layer 1 to routing some nets connected to some pins for nRF52832 inside inner 1. Which are the drawbacks to use these vias from top to bottom and isolate them (obviously) in the inner 2 and bottom layers? In this manner we certainly have a ground planes (in bottom layer and inner2 layer) not completely filled with copper but with some vias isolated underneath the WLCSP package but I do not think that this could lead RF poor performances. Many Thanks and Best Regards.

[Francesco_M]

Hi Kaja,

many thanks for your answer. Now I understand. I didn't know the microvia technology and now I learn that this particular vias built with a laser have an aspect ratio of about 1:1 and therefore usually connect only two layers. 

[Kaja]

Great! 

Also note: When you have designed a pcb, schematic or/and layout, feel free to upload the designs files to a DevZone case, call it HW review, make it private if you want it to be confidential, and we can give you a design review. 

Best regards,
Kaja