Hi folks,
I have a older proto board (an IF Demodulator) that was defined with an
asymmetrical stack up and I am concerned about the cost issues with leaving
it alone... Since we are changing the board at this time, I thought to check
for any issues with the design package and found this anomaly...

It looks like this:
.063 overall thick FR4 material

     0.070 max     ________________________ Top Layer Signal
.032 separation--->________________________ GND Plane
                   ________________________ Internal Signal
   0.00            ________________________ Bottom layer Signal

The odd part being, the forced separation between the ground plane and the
top signal layer where the RF components reside, primarily. Have you had any
experience with this sort of thing? Is there a good reference I can refer to
that deals with Board stack up issues?
Do you think the board is at risk for flatness problems?
The EE assures me that he knows of no known issues with the electrical
properties of the circuit that would require a stack up of that sort. He
says the only reason he can think of was parasitics and/or shielding.
Like to hear your thoughts....

- Bill Brooks

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