[SI-LIST] : Traces Over Plane Clearances

Dave Hoover (dhoover@mccurdy.com)
Fri, 6 Aug 1999 09:22:44 -0700

I have a customer who has a 2000+ I/O BGA with
tight pitch. They are using 2 track routing to
escape the device on the PCB. At the device,
the traces cross over the edge of the reference
plane clearances. The microprocessor and
clocks currently run at ~1 GHz (headed above 3 GHz).
The distance across that clearance would be
less than .020" in length. There is a copper
web of around .008" between the plane
clearances (thinking adequate signal return path).
My question is that the customer is afraid the short
distances without the reference plane will impact
his electrical performance properties.
The problem I face is currently the clearance size
is reduced to the point that it can't be manufactured.

Faced with a dilemma, so I went to the pros.

David Hoover

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