High performance thermal vias in LTCC substrates

Increased power densities in devices are placing greater demands in system level thermal management. New developments in low temperature cofire ceramic (LTCC) have allowed the fabrication of high thermal conductivity via arrays. New materials, including unloaded via inks and cofire Ag tape, allow the development of thermal via structure with effective thermal conductivities exceeding 250 W/m/spl deg/K. To accurately predict the thermal performance, the value of thermal conductivity must be known. Thermal conductivity has been measured by flash diffusivity for a number of commercially available LTCC ceramics and via fill materials, with the via materials approaching 300 W/m/spl deg/K.