Those DK values are average values only, and for frequencies of 1 MHz. The dielectric constant of base materials depends on the resin content of the base material, because it is a composite value of E-glass with a DK of 6.6 and neat resin (e.g. epoxy resin of 3.6). For epoxy/glass (FR4), irrespective whether difunctional or multifunctional, the DK range is from 4.3 (e.g. 0.15 mm laminate of 2 plies 1080 glass fabric, with a retained resin content of 56 %) to 4.8 (x plies of 7628 glass fabric, 41 % resin content, e.g. 0.33 mm, 0.51 mm, 0.71 mm, 1.50 mm). The same applies to polyimide/glass, with DK values from 4.0 to 4.6. And it is not possible to manufacture any laminate thickness for a given dielectric constant: e.g. it is not possible to manufacture a rigid epoxy/glass laminate (1.5 mm) with a DK value of 4.3. This would require approx. 23 plies of 1080 prepreg, resulting in slippage in the press, and manufacturing cost that nobody could pay for (23 plies 1080 vs. 8 plies 7628 glass ). For teflon laminates a DK value cannot be stated without the MIL designation, e.g. GX, GY, etc., because the nature of this designation also determines the construction of the laminate: A GY laminate automatically has a lower DK than a GX material due to the use of skived PTFE (= pure PTFE, without glass fabric reinforcement) in the laminate construction together with glass reinforced prepreg. Manfred Huschka AlliedSiignal Laminate Systems Europe ---------- Von: No Name An: Armando Saldana Cc: [log in to unmask] Betreff: Re: dielectrics for dif materials Datum: Mittwoch, 22. Januar 1997 19:43 Microsoft Mail v3.0 (MAPI 1.0 Transport) IPM.Microsoft Mail.Note From: No Name To: Armando Saldana Cc: [log in to unmask] Subject: Re: dielectrics for dif materials Date: 1997-01-22 19:43 Priority: 3 Message ID: D46E11B7BE74D011B4D600805FD4C991 ----------------------------------------------------------------------- ----- -- Dielectric Values FR-4 = 4.8 teflon = 2.4 Polyimide = 4.3 GETAK = 3.9 On Wed, 22 Jan 1997, Armando Saldana wrote: > attn: all in the TechNet Forum!! > > Can anybody out there tell me how I can > get the dielectric values for different > kinds of materials? > > FR4 = ? > Polyimide = ? > Teflon = ? > Kapton = ? > etc. = ? > > can i call a website or would ipc have this kind of > information handy at all times? > > i need this info yesterday so anybody with > any kind of help or hints would be greatly > appreciated!! > > thanks in advance! > > > Armando Saldana > [log in to unmask] > > *************************************************************************** > * TechNet mail list is provided as a service by IPC using SmartList v3.05 * > *************************************************************************** > * To unsubscribe from this list at any time, send a message to: * > * [log in to unmask] with <subject: unsubscribe> and no text. * > *************************************************************************** > * If you are having a problem with the IPC TechNet forum please contact * > * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * > *************************************************************************** > > ************************************************************************ *** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * ************************************************************************ *** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ************************************************************************ *** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ************************************************************************ *** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************