kicad-developers team mailing list archive

[jp charras <jp.charras@xxxxxxxxxx>]

Le 18/06/2015 20:17, Jon Neal a écrit :
> The code for placing a micro via in the push and shove router was just
> using the regular/through via drill size. Reported in this bug:
> https://bugs.launchpad.net/kicad/+bug/1464332
> 
> This fixes that, but I did notice that the code does not check to make sure
> that the layers are adjacent. There was a bit of back and forth on how to
> handle layers with micro vias since they technically only go from one layer
> to an adjacent, but they can also be stacked one on top of another.
> 
> I don't know enough about micro vias to put that sort of check in the code
> without other people's inputs.
> 
> Also, are blind/buried vias just the regular via size, or should they be
> micro vias?
> 
> Jon

Thanks. I just commit it.

Blind/buried vias are just regular via size/drill.

Technically, micro vias only go from one layer to an adjacent.
Depending on your board maker, they can also be stacked one on top of
another (i.e. they are Blind/buried vias) or not (this is a constraint
really subject to change).

Therefore, you can see micro vias as blind/buried vias.
However, when routing a board, it is really hard to see if a
blind/buried via is on a given layer or not.

Due to the fact micro vias are mainly used to connect a hight density
BGA to other layers, kicad (in legacy mode) accepts only micro-vias from
an external layer to the adjacent layer (you can use a buried via to
connect an other layer).

Of course, this can be discussed, but the advantages are:
1 - It is more easy to know what are the layers connected by a micro via.
2 - It is (by far) easy to place a micro-via: you do not have to select
the target layer when placing it.


-- 
Jean-Pierre CHARRAS