Aubrey,
Why would a L1-L3 or L4-L6 via on a 6-layer board be buried via?
Regards,
Istvan Novak
Oracle
On 6/9/2017 7:51 PM, Aubrey Sparkman wrote:
Si Guy,
technically, you have buried vias, not blind. Did you not specify an
impedance target to your supplier? Most I've dealt with are happy to adjust
your trace widths to hit your impedances; it's easy for them make the
adjustments unless your design widths are already at the limits of their
processing capability.
A common desire is to have a mil or more of copper for the via barrel wall.
This means you will also have similar amounts on the layer for each end of
the via.
Aubrey
Sent from my iPhone
On Jun 9, 2017, at 4:08 PM, SI Guy <silistguy@xxxxxxxxx> wrote:------------------------------------------------------------------
calculations/sims, not equations*
On Fri, Jun 9, 2017 at 3:58 PM, SI Guy <silistguy@xxxxxxxxx> wrote:
Hi Experts,
I did my first design with blind vias. It's already starting to kick my
ass AFTER I've already designed it. I realize the importance of contacting
board shop before design, too bad boss doesn't allow the engineer to
control that.
My question is then, experts, if blind vias are used say 1-3 and 4-6 on a
6 layer foil lamination board, do those inner layers also have to have
plating in addition to the bare copper thickness? Always?
I used 1/2 oz cu on all layers and expected only outer layers to have some
extra thickness from plating. Now a shop is saying no no no, 3 and 4 will
be plated too. Now my inner layer transmission line equations are jacked
up! Not to mention the outer layers too.
Sad day. =(
Any experience would help. What in the world is the right way to approach
these situations. Books and seminars say one thing but then life kicks your
butt. So frustrating!!!
Thank you, experts.
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