Dear Colleagues:

Currently, I am assigned for the backplane development of a new project,
occasionally, I am told that the 'via' is not permitted to put on in the
whole backplane.  I wonder much that on what considerations the
inhibition is based.  As a high frequency engineer, I surely understand
that the via will cause transit effects on the high-speed lines,
however, there are still many signal lines merely running with low
frequency, say, some control signals.

If this inhibition is wholly, the possible factor I can think about is
the limitaion of manufacturing capability. After all, for a backplane
with 4.5~5mm thickness, is it possible to use common via or even 'blind
vias'?  If the 'vias' are totally not allowed to be used, large space
will be wasted.

Appreciate for your possible echo.

C.-H. Huang

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