Fun times that.  Unbalanced in material thickness + single sided sequential lam to get the last core into the stack. Hope you have an experienced fabricator who is willing to plan some extra time into the process for long press cool down and a flatbake after.  Don't rush that.

Also, hope you're prefilling the blind via in the 62 mil core with a non-conductive epoxy (e.g. San-Ei PHP).  Doubt 4450 is going to have volume of free resin needed for that.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, September 5, 2017 10:21 AM
To: [log in to unmask]
Subject: Re: [TN] Multilayer PCB of Different Substrat Thickness RF Design

Hi Ricardo,

I finally have your picture posted, Richard was right, had some pressing things on the production floor to take care of after the long weekend.
Here's your stack-up drawing:

http://stevezeva.homestead.com/Ricardo_Stackup.jpg

Steve

On Tue, Sep 5, 2017 at 7:50 AM, Stadem, Richard D. <[log in to unmask]
> wrote:

> Hi, Ricardo
>
> I do not have the capability to post your picture, but I am sure Steve 
> can, and I see you have copied him.
>
> Being that many people are taking vacations here this week as part of 
> Labor Day weekend, not sure when Steve will be in. You may need to 
> wait until later today.
>
> In looking at the stack-up, I do not have a lot of expertise in this 
> area, but I do know that having differing layer thickness can maybe 
> cause some issues with different coefficients of thermal expansion 
> during reflow and other heat excursions. This can put stresses on the 
> vias passing all the way through the board. But I am not an expert in 
> those issues. One suggestion; you would be wise to also pose the 
> question to the Designers Forum. I am sure they can give you plenty of advice on that.
>
> 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
>
>


--
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133

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