Tom, The thermal properties of PCB materials are dependant on the resin type and glass content (I expect the electrical properties will also). Most materials suppliers are still very poor at providing relevent materials properties despite the use of simulation systems such as you described. We have just measured some 1.6mm MAS FR4 material to have an SHC varying from 1300J/kgK at 50C to 1650J/kgK at 130C (then remaining constant up to over 200C). Thermal conductivity is orthotropic, but in general though thickness temperature gradients are relatively small so the in plane (XY) figure is most important (and is usually much more important than SHC). It is also difficult to measure accurately. We tend to use a textbook figure of 0.25W/mK. If anyone else has any more data they are prepared to share I would be prepared to create a WWW page collating the data. David Whalley