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Date: | Wed, 08 May 96 14:30:43 EST |
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(From the original file sent to Doug. Due to popular demand)
I'm not a designer but a fabricator in charge of what I
call "bleeding edge". My experience with RF and FR-4 leads me to
believe "you can't get there from here". I've heard of transceivers
with multilayer PCBs going to 6 and 8 Ghz, but these guys are pros.
Microwave gurus who plug their designs into SPICE for 2-3 wks before
they build protos. They acquire the protos and take readings that
they plug into their SPICE library. (Constantly gaining real data)
If their far off, they tweak and build new protos until they get
it. The cost of 2 or 3 proto builds still is not as steep as PTFE
multilayers.
Their is new materials out there that are targeted to fill the
RF gap between PTFE and FR-4. Starting with a Er of 4.2, One of the
PTFE manufacturers now has a rigid mat'l with a low Dk, A new
continuous laminate manufacturer is making something that looks
very promising at Er 3.3. The only problem is that these materials
generally are only available in a few thickness'and prepreg is not
yet available and we have to use something different to bond them
together.
Let me know if you get some resolution or design related
suggestions. I like to stay current with this kind of stuff.
Dave Hoover (Groovy)
(This post has been modified from it's original text so that
everybody else can see the direction of the response. <Leaving
vendors names off>)
______________________________ Forward Header __________________________________
Subject: PC Board Frequency Limits
Author: [log in to unmask] at SMTPLINK-HADCO
Date: 5/7/96 10:09 PM
I would like any responses to be off-line for the following
discussion.
Please use the following email address: [log in to unmask]
I made a simple mathematical model of a stripline, 1 inch trace, on
FR-4, nothing out of the ordinary as far as dimensions and found to my
surprise a resonant freq at about 800 MHz with a 20 to 40 dB roll-off
above 800 MHz
Could someone in the RF/Microwave world of nuts and bolts pc board
design tell me what I'm supposed to do at say 10 GHz with regular pc
board materials/construction/fabrication???
Thanks in advance, Doug McKean
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