One other point about buried & blind vias: Most garden-variety PCB fab houses can't do them. Check with your PCB vendor & verify they have that capability before you get deep into a design using them.
Stuart > not quite! but we are looking into 6 layer boards for PC applications, ru= > nning at a few hundred MHz. > I am worried about signal reflections from such large height vias. > Thanks > Amr > > Stuart Brorson <[EMAIL PROTECTED]> wrote: Ummm, are you sure you need to use= > buried vias? Most PCB fab houses > don't support them; they are used on super-dense, high-tech boards, > and you pay mucho extra $$$ to get them. They are not used on > entry-level to mid-level boards. =20 > > If you *are* using PCB to design a 20 layer OC-192 router board with > 10Gig diff co-planar waveguides and 622Mbps parallel busses, then > bully for you! Let us know how it goes!=20 > > Stuart > > > > Hello > > Is there a work-around to the absence of buried vias? for example,=3D20 > > edit the drill file to remove a specific thru-hole, and copy this=3D20 > > via into the file for layer 2-3? > > Best Regards > > Amr Bayoumi