APPLICATION OF THE LASER FLASH DIFFUSIVITY METHOD TO THIN HIGH THERMAL-CONDUCTIVITY MATERIALS

The evolution of semiconductor devices and the dramatic increases in t he power dissipation per unit volume of ever smaller microelectronic d evices means electronic packaging technologies must evolve to manage t he dissipation of heat. One of the major issues is the development of new packaging materials optimised for heat management. Future packagin g will incorporate layers with thermal diffusivities exceeding that of copper in thin, sub-millimetre foils. Metrology techniques are needed to measure the thermal diffusivity of these thin, thermally fast mate rials. As some new materials are developed only in the form of thin su bstrates the laser flash technique is limited in its application to th ese materials. This paper addresses the application of a nanosecond pu lsed laser flash instrument to the measurement of thermal diffusivity of thin high thermal conductivity materials and the errors associated with the measurement. An experimental comparison is made with a laser flash instrument where the laser pulse is of higher energy but millise cond pulse duration.