Using uVias, Vias.

[Khai]

Hi Robert and everyone,
I have a question about using Vias, uVias in iMx6.
Can I use Vias with the size drill: 0.27mm / 0.1mm (11mil / 4mil) when I routing signals and I use Vias with the size drill: 0.45mm / 0.2mm (18mil / 8mil) when routing powers?

[mairomaster]

For the different via sizes you should speak with your PCB manufacturers. The sizes you quote will require a reasonably high-end one. It also depends on your stack - remember that with micro vias you should have an aspect ration (height to drill diameter) of 1 in the best case. So for 0.1 mm drill the distance between the particular layers should be 0.1 mm maximum (this can vary a bit depending on materials, manufacturer capabilities, etc).

[robertferanec]

I just try to add more information to the mairomaster answer. Basically, there is VIA hole size limitation based on the thickness of PCB you are drilling through. The main issue is plating (the process of putting copper inside the VIA). So, for example, PCB manufacturer would not be able to connect TOP and BOTTOM layer of your PCB, if PCB thickness is 1.6mm and you drill 0.1mm hole. They call this parameter aspect ratio and it is usually 1:10 or 1:12 for standard through hole VIAs, that means, the smallest hole which you can use for through hole 1.6mm thick PCB is 0.16 or 0.13mm hole. Also, many manufacturers will not be able to drill 0.1mm through 1.6mm thick PCB. So, if you would like to do something like what you are suggesting, you need to use blind or uVIAs and you definitely will need to speak to your PCB manufacturer.