Jeff,

Word of advice...and this is a rule and a fab note we use for all designs.
We specify  a MIN  core and prepreg  thickness for all layers, in one fab
note. We spec .0035 inch min.   This gives your fabricator the latitude to
adjust for copper distribution, laminates he has in stock, epoxies,
pressing, over all thickness variations, etc.  The only conditions in which
we specify a thickness and we only spec it for these layers, are controlled
impedance, and where the min dielectric breakdown voltage is required for
Bell-Core, FCC, and space applications.   My advice is to leave the majority
of your stack up determined by your board house, unless you have specific
reason to do otherwise.
The IPC spec in 6012 for level 3 is to specify a design so that any board
house can build your design with the same result.   Remember you are
designing/ writing  a specification,  give the fabricator some latitude


Mike Reagan
EDSI
Frederick  MD

> -----Original Message-----
> From: Jeff Adolphs [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 09, 2001 9:22 AM
> To: Protel EDA Forum (E-mail)
> Subject: [PEDA] Layer Stackup Info.
>
>
> Hello,
>
> What IPC Standard shows core and prepreg sizes? I have IPC-6011,
> IPC-6012A,
> and IPC-2221 which do not have this information.
> ( at a IPC workshop I was shown some slash sheet that had the
> sizes and told
> it was in IPC-6011 but I don't see it there, I also got the
> impression I was
> an idiot for not having all the IPC standards --I don't work for a large
> company that buys everything and my company won't buy me $400 design
> guides!! It wasn't easy to get the standards I have and frustrating when I
> buy the wrong ones.)
>
> I have been told I should be telling on the Fab Layer the Layer Stackup
> Info. I have only been specifying two thicknesses 0.080 +/-
> 0.006" or 0.062
> +/- 0.006". The problem is I don't know the core and prepreg sizes. The
> second problem is I don't know the PCB manufacturers stocked core and
> prepreg sizes.
>
> Finding out what cores and prepreg sizes are stocked at the PCB
> manufacturers will be time consuming and a pain in the $#&. I have had
> trouble with 0.080 +/- 0.006 PCBs coming in as 0.062 or 0.092 which is out
> of my specification.
>
> Sincerely,
>
> Jeff Adolphs
> Lake Shore Cryotronics, Inc.
> Westerville, Ohio, USA
>
>
>
>

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*                      - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to