kicad-developers team mailing list archive

[Andrey Kuznetsov <kandrey89@xxxxxxxxx>]

Should kicad not impose 2 layer restrictions on blind/buried vias? That way
users could at least use them, but will have to manually be careful since
DRC doesn't support it. There could be 2 blind/buried vias on top of each
other vertically, but on different layers and not touching.
And have unlimited adjacent layer selection, from<->to.

If it's limited to 2 layers, users wouldn't be able to properly use
blind/buried vias.

On Sun, Jan 7, 2018 at 6:01 AM, jp charras <jp.charras@xxxxxxxxxx> wrote:

> Le 06/01/2018 à 22:58, kristoffer Ödmark a écrit :
> > I am implementing it now, just a question, what should be the logic
> behind micro vias? Not very
> > familiar with those.
> >
> > Can they go between any number of layers, or only adjecent ones? I will
> treat them like buried vias
> > currently, so that they can go between any two layers.
>
> Micro vias and buried vias have constraints.
> These constraints are highly dependent on board makers but usually these
> vias cannot go between any
> two layers.
>
> micro vias are in fact laser drilled vias, and the hole is not a cylinder,
> but a cone.
> the max depth (Z dimension) depend on the hole diameter.
> If we restrict laser drilled vias to 2 adjacent layers, it should work in
> any case (although a bit
> restrictive).
> This is one of reasons in Pcbnew microvias are only blind vias restricted
> to adjacent layers.
> More than 2 adjacent layers is certainly possible, but only the board
> house can say that.
> Of course standard blind/buried vias have also limitations, and cannot go
> between any layer pair.
>
> For instance, see
> https://www.eurocircuits.com/blog/blind-and-buried-vias/
> and
> https://www.pcbcart.com/pcb-capability/blind-and-buried-vias.html
> for limitation examples.
>
> And keep in mind limitations depends on the board house that will make
> your board.
>
> Currently, Pcbnew is missing a layer stack manager (coming for V6), and a
> dialog via properties
> cannot safely manage the layers pairs of non through hole vias.
>
> Also keep in mind changing a via setup should be tested by the DRC
> (clearance test) and the ratsnest
> rebuild if layers change (or if the size is smaller).
>
> --
> Jean-Pierre CHARRAS
>
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kandrey89@xxxxxxxxx
Live Long and Prosper,
Andrey