Alumina with a Thermal Conductivity Close to Beryllia

Previous studies on special dielectrics for multilayer screen printing led to defining a new concept for standard alumina substrate. The modification of the process and structure permits an increase of the thermal conductivity. The thermal conductivity of this new material is between that of alumina and BeO. It is possible to increase the thermal conductivity of 94% standard alumina (used in chip‐carriers) up to 3·6 times. It it known that the thermal conductivity of beryllia is 7 times higher than that of alumina. The thermal model gives an increase of 4 times for other configurations non‐tested in this study. With this material, the other characteristics such as thermal expansion, adhesion of the conductors, etc., scarcely change. The ‘percolation’ effect of the physical properties can usually be found with the addition of another material inside the matrix. In this particular case, the material is not submitted to the percolation law. Different configurations of metallic insert alumina with beryllia are compared by a simulation programme. The main applications are in the field of electronic packaging such as chip‐carriers with higher thermal dissipation and substrates for power devices. Since the process used to produce this new material is based on standard operations well known by alumina manufacturers, the cost is potentially much lower than for BeO.