Based on Norman Einarson's "Bare Board PWB Design Manual":

FR-4 is a flame resistant glass epoxy.

Tetrafunctional means that there are four sites per molecule after
polymerization, as opposed to two sites per molecule in regular
(difunctional) FR-4.  The result is that tetrafunctional FR-4 is denser,
more acid resistant, more stain resistant and has a higher glass transition
temperature.  I believe that this will also be more expensive.

Hope this helps.

-Steve

Steven K. Lustig
Process Engineer
EMS Technologies, Inc.
Norcross, GA
(770) 263-9200 x4714
[log in to unmask]


-----Original Message-----
From: Parvez M.S. Patel [mailto:[log in to unmask]]
Sent: Tuesday, December 07, 1999 9:43 AM
To: [log in to unmask]
Subject: [TN] What do we mean by FR-4


Hi everybody,

I was wondering what does FR-4 stand for..

and what do we mean by tetarfunctional Fr 4 (as in boards)

Thanks in advance




Parvez M.S. Patel
Graduate Research Associate,
Universal Instruments Corporation,
SUNY - Binghamton, New York.

Ph:     607 779 7215(O)
Fax:    607 779 4646

*************Equilibrium is death. Seek persistent
non-equilibrium***************

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