GFN originated in a now obsolete Mil spec - MIL-P-13949 which became
MIL-G-13949.

1.2.1.1.1 Base material. The base material for metal-clad laminates is
identified by three letters,
with. the first letter representing the reinforcerrent, the second letter
representing the resin, and the third letter representing special
considerations.

G for glass fabric woven
M and F for flame resistant epoxy

The third letter shall be as follows:
N For natural color of resin system.

This specification also had what they refered to as SPECIFICATIONS sheets,
commonly refered to as 'slash sheets'

GFN was /4

I don't have a copy of this slash sheet but as I remember it called for a
glass transistion temperature  (Tg) of either 105C or 130C minimum.  All of
the laminate manufactures will have a resin that will meet this requirement.

What IPC-4101 did was to create slash sheets (/21 for example calls for Tg
of 130 minimum, /24 170 etc.) They also created a  cross reference to the
old 13949 to IPC 4101.  So if you get a copy of 4101 you can do the cross
reference.

Good Luck

pete












>From: Franklin D Asbell <[log in to unmask]>
>Reply-To: TechNet E-Mail Forum <[log in to unmask]>,              Franklin D
>Asbell <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: [TN] GFN 4101
>Date: Fri, 10 Dec 2004 13:19:34 -0600
>
>GFN I believe is regular FR4...the initials meaning Glass-Fiber-Natural
>(natural being the color...green...go figure)
>
>I believe also GFN would be 4101/21 unless a higher Tg is specified with
>it...
>
>Franklin...
>
>----- Original Message -----
>From: "Rodney Miller" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Friday, December 10, 2004 12:45 PM
>Subject: [TN] GFN 4101
>
>
>>We don't do lamination, as an assembler, however we do have a request
>>for a special PCBA which is using GFN Laminate.
>>
>>Broad search reveals a tech sheet for Isola 406BC which is from Isola.
>>
>>Is the GFN a special grade of FR4 or is it a PCB fabrication certificate
>>as to reliability etc?
>>
>>The Fab drawing refers to IPC 4101, but I don't have one of these handy.
>>
>>For all I know, its a spec that has been replaced as an obsolete mil
>>spec....
>>
>>Any news is news,
>>
>>Thanks
>>
>>Rodney L. Miller, CID
>>VP / Director of Manufacturing
>>Tri-onics Inc.
>>ph (618) 654-9831
>>fx  (618) 654-6122
>>e   [log in to unmask]
>>
>>
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