01-07-2016 08:30 AM - edited 01-07-2016 08:33 AM
Hello.
I'm using Ultiboard 14 and trying to make 4 layer PCB in which most top and bottom layers are for signal routing while inner layers are power and ground plane in order.
I've set 4 layers in PCB Properties by setting (Layer pairs to be 2) or (Layer pairs to be 1 and Single Top to be 2 under Single layer stack-ups).
I surprisingly find that all allowed vias shown doesn't make complete combination between layers. For example, in 2nd setting above, there is no via from Top Stack-up 2 (to be layer for signal and component placement ) to Copper Top (to be ground plane)! Without this via, direct connection from signal&component layer to ground plane is not possible.
Maybe I can use Through board via with anti-pads on 2nd and 3rd layers and blind via from 3rd layer to most bottom layer (I even don't know how to place anti-pad around the via so far...), but...I think it should not be complicated at that level.
Why can't I use simple via from 1st to 3rd layer?
01-07-2016 10:52 AM
Hi Goodphy,
My understanding is that because of the way multi-layer PCBs are constructed, with alternating layers of core and pre-preg material (fiberglass), a common limitation of PCB manufacturing is that vias must cut through an even number of layers. See this article for a more detailed explanation. Have you checked with your PCB manufacturer to confirm that they allow vias from layer 1 to 3?
If you add more layer pairs to your board you will have more possible combinations for blind vias, but I believe in a 4-layer board most PCB houses commonly limit blind vias to either layers 1-2 or layers 3-4.
I hope that helps, let me know if you still have questions.
Jeff
03-01-2018 06:00 PM
Hi,
Did you solve this problem?
If you have, could you provide me the solution ASAP.
Regards,
Dinesh K