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Allowable vias on 4-layer PCB
474 1 Jun 28.2019, 09:37:48

This is possibly question many times answered, but with my searching skills I didn't find a straight answer yet: what type of trough hole and blind vias are allowed on 4-layer design?
I'm going to make my first 4-layer PCB, and came into position for the first time to think about it and immediately stuck. Here is what I presume that is possible, or better to say, a proper usage of multiple layers:

Top (1) and bottom (16) layers should be used for signaling, upper middle layer (2) is GND, and lower middle layer (15) is for power. All SMT parts will be on the top layer therefore for the signal trace connecting between 1 and 16, trough hole via should go from top to bottom. But, for GND and power, I'd like to have 1-2 and 1-15 type of blind vias. In summary it should looks like this:

I've checked design rules file from few PCB manufactures, and nobody offer such "freedom". In most case I can see that trough hole via (1-16) is allowed.

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Jul 02.2019, 17:58:27

Blind vias: 1-2, 3-4.
Buried vias: 2-3.
Through vias: 1-2-3-4.
Other combinations (1-3, etc.) require a combination of blind and buried via technology, and that requires precision alignment of vias drilled in different processes, which implies super high precision that's practically only possible with laser drill, hence high equipment cost.
So basically, 2 vias don't stack on top of each other without laser drilling technology.
Therefore, most low cost fabs will only do either blind or buried vias, not at the same time.

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