Conduction in orthotropic media is a special case of conduction in an anisotropic solid whereby thermal conductivity is different in each of the principal orthogonal coordinate directions. Since we are only interested in orthotropic media, the reader is referred to Carslaw and Jaeger (1959) or Ozisik (1993) for more details on anisotropic heat conduction. In general, the orthotropic system is the more common application found in microelectronics and hence, most if not all studies cited come from this field.