This message is resent,.somehow it got sent before I was done..(monday's!) On 10 August 1995, Dougal Stewart wrote: >> We have a customer who has been asked by his designers to >> provide boards with a CTI of greater than 400 and a flammability >> rating of 94V-1. They also ask if standard FR4 will comply - at >> least I know the answer to that one. >> I am not sure what laminate will meet this requirement - FR3 >> has been suggested, but laminate suppliers always leave off >> the CTI when quoting electrical properties. Dougal, I sent a response Friday to the second-half of your post, but then came across this message that I hadn't read yet. I would like to add a little more to the post I made Friday to help make that information a little more useful. When you speak of CTI, I'm not exactly sure what is meant by that...I don't believe it's coefficient of thermal expansion (CTE) because the values are expressed in parts-per-million...and I can't think of why anyone would want a laminate that has a CTE of 400 ppm anyway, so I'm assuming what it is that you're asking for is laminate that has a glass transition temperature (Tg) of 400 degrees F. or above...that works out to 204.44 degrees celsius (400-32 x 5/9=degrees C.)...I'll list below the important properties of the materials I refered to in my last email: ** Reinforcing Materials ** Dielectric CTE,ppm/degree C. Constant Material @ 1 MHz Long. Radial E-Glass 5.5 5.5 5.5 S-Glass 4.5 2.6 2.6 D-Glass 3.6 3.1 3.1 Quartz 3.8 0.54 0.54 Kevlar-29 4.1 -4.0 60.0 Kevlar-49 4.1 -5.0 60.0 E-PTFE 2.0 70.0 120.0 ** Bonding Resins ** Glass Transition Generic Dielectric Loss Temperature Resin Type Supplier Constant Tangent (Degrees C.) G-10FR /FR-4 Norplex 3.6 .032 125 RSM-1212 /FR-4 Shell 3.6 .032 125 Quadtrex 5010/Tetra. Dow 3.6 .032 180 RSM-1151 /Tetra. Shell 3.6 .032 180 G-200 /BT/Epoxy Norplex 3.2 .012 185 BT2110F /BT Mitsubishi 3.1 .003 250 BT2060BG /Modified-BT Mitsubishi 3.9 .001 220 Kerimid /Polyimide Rhone Poulenc 3.2 .020 275 RSM-1206 /Polyimide Shell - - - RDX 64826 /Cyanate ester-I Interez 3.1 .005 260 XU-71787 /Cyanate ester-IV Dow 2.8 .004 260 UDEL /Polysulfone Union Carbide 3.0 .004 192 ULTEM /Polyetherimide General Electric 3.1 .0065 260 Notes: * All temperatures are in degrees C.) * Tetra. is abbreviation for Tetrafunctional Epoxy * BT is abbreviation for Bismaleimide Triazine, also known as Cyanate ester * RSM-1206 is usually provided as a blend with epoxy. //// | @@ / Steve Gregory C ) Process Training Engineer //// \_o Pragmatech Incorporated | @@ / 101 Nicholson Lane C ) San Jose, California 95134 \_o //// [log in to unmask] | @@ / Phone:(408) 943-1151 C ) Fax:(408)943-1461 \_o -------------------------------------------------------------