Abdul and Brad,
If your design is critical to a particular thickness, then yes you must
specify it. no doubt, however if it aint, specify the min acceptable and
give your design house the latitude to build up. Funny we are all on this
subject, I plan to submit a paper to PCD magazine, about board specification
and fab notes later this month or early next month.
> -----Original Message-----
> From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 09, 2001 5:15 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] Layer Stackup Info.
>
>
> At 08:41 AM 7/9/01 -0700, Brad Velander wrote:
> >Michael,
> > while I can generally agree with your advice you leave
> one aspect
> >wide open. If you do not specify your layer thickness, you could
> get a board
> >that works fine from manufacturer A, switch to manufacturer B and have a
> >board that doesn't work fine.
>
>
> I want to underscore this.
>
> If one is comfortable with a particular fabricator, there is no
> harm asking
> that fabricator what thicknesses they would recommend based on what is
> easily available, and then writing that into the board stackup
> specification. Work with the fabricator.
>
> The down side of this would be that a less than scrupulous
> fabricator might
> suggest a thickness that they happen to have a lot of and need to
> dump. But
> that is not very likely.
>
> IPC-2222 does have a table of laminates.
>
> If you join the IPC Designer's Council, $50, you get -- last time
> I looked
> -- a $50 credit toward publications, *and* you get the
> publications at the
> member prices.
>
> The sizes of FR-4 material marked in the chart as low cost are, in mm.:
>
> 0.07
> 0.11
> 0.13
> 0.18
> 0.26
> 0.32
> 0.37
> 0.43
> 0.53
> 0.61
> 0.64
> 0.74
> 1.52 is not given the lowest cost value, but it is very available.
>
>
> Abd ul-Rahman Lomax
> LOMAX DESIGN ASSOCIATES
> PCB design, consulting, and training
> Protel EDA license resales
> Sonoma, California, USA
> (707) 939-7021, efax (419) 730-4777
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
>
>
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* 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
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
