Let me tell you about vias. First of all, I have used vias many time on high
speed busses with no
Problems in the past. In fact I had the same problem You mentioned with a
Particular Engineer.
I'm a Engineer my self, but I actually Design PCBs for about 8 years now.
What I'm trying to get at is, I Design 2 boards of the same circuit, one
with vias on the High speed bus, and one with out it. To tell you the truth
there was no electrical difference or performance difference that we could
detect.
The only major difference we encountered was time , one took about 8 hours
longer to route, You can probably guess which one it was.
Hope this helps, It helped me convinced a particular engineer in changing
his (all life beliefs).
Patrick Jabbaz
Halliburton Energy Services
Circuit Board Designer
(281) 596-6697
[log in to unmask]
-----Original Message-----
From: Ras Huang <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Thursday, April 09, 1998 10:09 PM
Subject: [DC] 'Vias' on a backplane
>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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