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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 16 Nov 1998 14:37:31 EST |
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ed:
the following is an explanation of the referenced slash sheets to 4101:
L/24: note the Tg range of 150 to 200°, which translates to FR4's known as
high temperature or high performance, such as PCL's 370 or AlliedSignal's 406
or Nelco's 4105-6. Their chemical makeup is generally 100% multifunctional
resin (un-blended with difunctional.)
(fyi, Polyclad's "standard material 1226FR is covered by /21.)
L/25: this covers GE's GETEK version of a high temperature FR4, which has a
resin copolymer containing the thermoplastic PPO for lower Dielectric
Constant.
L/26: Not a tetrafunctional. This covers the BT type materials when you want
to use them for a drawing calling out type GF. Note that BT is a blend of a
Cyanate Ester type resin with epoxy, which is the point of the "modified ...
epoxy resin" reference. This slash sheet also allows other epoxy-based
materials with a higher Tg (170-220°) besides BT to be used.
FYI, slash 30 is intended to apply to BT materials also. The ID Reference of
"MIL-S-13949/26 - GFT" is an error. It should refer to 13949/24 and 26 - Type
GMN.
Hope this clears up some questions.
jimpaulus
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