IPC-4101 defines the standard for rigid laminates.  It gives reasonable
tolerances and target values for primary characteristics as to mitigate the
effect of changing vendors.  However, even under this specification there
will be some variation from manufacturer to manufacturer on material
performance, but these variations should not be any greater than the
variation from fabricator to fabricator using the same material.

Jeffrey A. McGlaughlin
Sr. PCB Designer
Battelle Memorial Institute
Columbus Ohio
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        -----Original Message-----
        From:   Cates, Thomas [SMTP:[log in to unmask]]
        Sent:   Wednesday, 15 March, 2000 17:38
        To:     [log in to unmask]
        Subject:        [DC] Broard mat'l standards

        Hi -
        I'm a PWB designer and I need to convince some engineers I work with
that we
        do not need to specify brand names of the FR-4 board material. They
feel
        that since they tested the physical properties of a certain brand of
FR-4
        that we need to call that brand out in the FAB drawing note. In one
case the
        company is no longer in business. I maintain that we will be safe
and more
        flexible if we call out "Epoxy-Glass Laminate FR-4..." Is FR-4 made
to some
        industry standard? If so how can I get a copy of this standard so I
can
        prove my point once and for all?
        -thanks
        Thomas Cates
        Intermec - Amtech Systems Division