Frank,
Yours are unvaluable considerations for us.
We are analyzing matter and will feed you back.....
Thanks to all of you.
brgds,Ricardo
 
>>> Frank Kimmey <[log in to unmask]> 05/09/2017 11:50 >>>
Ricardo,
I see some concerns here definitely.
Just a quick walk through of the processes looks like this design would
require a multiple lamination cycle and numerous plating cycles.
I’ll try to explain:
L3-L4 drill, plate and etch L3
Laminate adding L2 then drill, plate and etch L2
Laminate adding L1 then drill, plate and etch L1 and L4
As you can see there would be 3 plate processes to put L4 through
causing the need to planerize (remove copper) or etch to reduce overall
copper thickness. Also you will see considerable warpage due to almost
all stress being added to the lower numbered layers as the stack up
increases.
I’m not sure you will have a lot of luck finding PCB Fabs willing to
build this option.
You might want to rethink the blind via options and maybe try buried
for L2-L3 (you might be able to stagger a blind from L4 to L3 to make
your L2-L4 connections), this would allow for 1 less lamination/plate
process and may help with the stresses. 
Next thing to look at is the substrate, you want to mix a duroid
material with a thermoset plastic material and bond them with adhesive
film. This is doable but your final finish will play a role on how
susceptible your finished PCB is to delam.
Have you talked to you PCB Fab suppliers? They NEED to be involved in a
design such as yours if you want it successful.
Let us know how it turns out or if we can help in any other way.
Thanks and good luck,
FNK
Frank N Kimmey CID+
Electrical Engineer / PCB Design
VeriFone Inc
1400 W Stanford Ranch Road, Suite 200
Rocklin, CA 95765 USA
W: 1-916-625-1818
M: 1-916-833-9877
[log in to unmask]
From: Ricardo Moncaglieri [mailto:[log in to unmask]]
Sent: Tuesday, September 05, 2017 7:18 AM
To: Richard D. Stadem <[log in to unmask]>; Frank Kimmey
<[log in to unmask]>
Subject: Re: FW: Multilayer PCB of Different Substrat Thickness RF
Design
Frank,
Keep awaiting your feedback.
Richard,
Thank you for your assistance.
brgds,Ricardo
>>> "Stadem, Richard D." <[log in to unmask]> 05/09/2017 11:16
>>>
Frank, I can send the stackup directly to you, see it below.
Richard
From: Ricardo Moncaglieri [mailto:[log in to unmask]]
Sent: Tuesday, September 05, 2017 8:34 AM
To: Stadem, Richard D.; Steve Gregory
Subject: Re: Multilayer PCB of Different Substrat Thickness RF Design
Steve, Richard,
Would you pls upload the herebelow quoted image inord to be more clear
on my quetion to the forum?
Indeed hope to receive your comments / advise.
Keep awaiting.
Thank you very much, brgds,Ricardo
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated colleagues,
Nice to get in contact again with all of you after a bit long time.
We are deploying a RF design and by first time we intend to use a
multilayer pcb with different substrat thickness as shows the stack-up
herebelow detailed.
Questions here are:
As per your experience, is it recomendable such a kind of substrat
design?
Some pcb provider reported it is very difficult to achieve. Can you
recommend or share your background about pcb provider who can assure
high reliability on this pcb provision?
Keep awaiting for your unvaluable feedback.
brgds, Ricardo
Ricardo Moncaglieri
QA Electronic Service Manager
INVAP SE
www.invap.com.ar
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