Jim

You're venturing into the world of what I call "modified" epoxies.  I'm
generalizing a little bit here but these materials are typcially a high Tg
FR4 resin system combined with another resin.  The result typically is
improved electrical properties (lower loss and less frequency dependence for
both Dk and loss).  Just about every material supplier has a formulation of
this type out there:  MEM = Megtron, Isola = FR408, Nelco = 4000-13,
Polyclad = Getek.  But not everyone uses the same "modifying" resin system.

Because the /25 designation specifically identifies the secondary component
of the resin system as polyphenylene oxide (PPO), calling for that slash
sheet limits you to materials with that specific resin system.  I know of
only two materials that specifically use PPO:  Getek and Megtron.  Nelco
4000-13 uses triazine as the secondary resin, thus it falls under /29 (see
link below).

http://www.parknelco.com/parknelco/ipcspecs.htm

This is a trend that seems to be getting worse (in my opinion).  While the
improvements in new material systems over good old FR4 have resulted in much
better materials, it's starting to get to the point where each suppliers
material is unique.  The ability to just specify FR4 or an IPC slash sheet
for board material and then have the fabricator choose the material supplier
is fast disappearing.  More and more the IPC slash sheets are starting to
look like generic versions of the material supplier properties sheets.  Many
slash sheets now have only one or two suppliers associated with that
material.

As for Dk information, you should be able to find tables at the material
supplier webpages.  GE/Polyclad even has a little calculator you can
download.

http://www.geplastics.com/electromaterials/getekconnect/tm_main.htm

Whatever you do, don't use the electrical property values from the slash
sheets.  They are maximums.  I don't know of any FR4 materials with a Dk as
high as 5.4.


Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263



> ----------
> From:         Marsico, James[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Marsico, James
> Sent:         Wednesday, February 25, 2004 7:41 AM
> To:   [log in to unmask]
> Subject:      [TN] IPC-4101 Material
>
> Good day...
> Our designers want to use an FR-4 material which is designated as
> IPC-4101/25.  The /25 material has a permittivity of 4.4, while the other
> FR-4 materials (/21and /24) are listed as 5.4.  I found out that GETEK is
> classified as /25, and was wondering if this is the only /25 material
> available.  Is there a generic (or product) name for the /25 material?
> The
> slash sheets in 4101 have a maximum permittivity at 1 Mhz, do the graphs
> exist that show the Dk at various frequencies?
>
> Jim Marsico
> Senior Engineer
> Production Engineering
> EDO Electronics Systems Group
> [log in to unmask] <mailto:[log in to unmask]>
> 631-595-5879
>
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