thanks Harry & Jeff
the guidlines were good
i am not doing impedance control, and they show more thicknesses than i
had imagined - glad i'm not a fab shop!

looks like i can pick one that will be plenty close
and run that by my fab now that i am not just picking numbers out of
the air

Dennis Saputelli



"H. Selfridge" wrote:
> 
> The standard thickness of core material depends on who makes the laminates
> used by your fab.
> 
> If your fab can't make the board to your required dimensions, you need to
> call around and see what other fabs can get/do.
> 
> An example of available material from one laminate manufacturer can be seen at:
> http://www.chemitalic.dk/content/articles/dfmmatsel.htm
> A table of available laminates can be seen in design guidelines from a fab at:
> http://www.tru-lon.co.uk/pdf/guidelines.pdf
> 
> Finished thickness for prepreg and some cores can be different from the raw
> thickness as supplied.  When heated and pressed in the laminating press,
> some reduction in thickness of the individual layers tends to occur.  The
> data sheet from the laminate manufacturer gives the raw and finished
> thicknesses.  Again, the best source of information is from the fab.  If
> you're controlling impedance, the finished thickness data is essential for
> modeling stripline and microstrip characteristics.
> 
> At 11:56 AM 10/3/04, you wrote:
> 
> >is there a table of standard core thicknesses somewhere?
> >
> >i have a 6 layer stackup
> >
> >top
> >     prepreg
> >sig
> >     core
> >gnd
> >     prepreg
> >pwr
> >     core
> >sig
> >     prepreg
> >bott
> >
> >and am trying to hit 062" overall thickness within +-005
> >
> >what are all the material thickness possibilities out there?
> >(well maybe not ALL of them :) )
> >
> >given 007 prepreg and 021 cores
> >my vendor tells me that once you add the copper thickness at 1oz
> >the overall is about 071" thick
> >
> >sounds like 017 cores would do it, but that also sounds like a wierd number
> >
> >thanks for any help
> >
> >
> >Dennis Saputelli
> >
> >
> >--
> >_______________________________________________________________________
> >Integrated Controls, Inc.           Tel: 415-647-0480  EXT 107
> >2851 21st Street                    Fax: 415-647-3003
> >San Francisco, CA 94110             www.integratedcontrolsinc.com
> >
> >
> >

-- 
_______________________________________________________________________
Integrated Controls, Inc.           Tel: 415-647-0480  EXT 107 
2851 21st Street                    Fax: 415-647-3003
San Francisco, CA 94110             www.integratedcontrolsinc.com




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