From: Aric Hadav (Aric@accord.co.il)
Date: Mon Dec 11 2000 - 03:11:08 PST
I'm looking for some help on deciding on my board layer stackup.
my design has ~20K pads and it must fit into a standard 6U board, 1.6 mm
the board thickness CAN NOT be changed.
the PCB layout guy told me that the design can only fit into a minimum of 14
layers stack up,
with a 3-4 mil core and preg thickness, as described below:
5. sig3 (ctrl impedance).
9. sig6 (ctrl impedance).
now, this looks some what strange to me since layers 5 & 9 aren't adjacent
to a PWR/GND
plane, since one should always try that a signal layer will be close to
now, in order to reduce the crosstalk between layers 4 to 6 or 8 to 10 he
suggested to route the
signals not horizontally and vertically but
layers 4, 8 - 45 degrees.
layers 5, 9 - vertical or horizontal.
layers 6, 10 - 135 degrees.
has anyone routed this way ? did it work ok ?
the signal clocks will be routed in layers 5 and 9 which supposed to be
control impedance. is it ok ?
has anyone has other suggestions to the layer stuckup?
Hardware Design Engineer
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