Multifunctional Interfaces for Combined Mechanical, Thermal and Electrical Properties

摘要

Interfaces between heterogeneous materials exist in many applications and affectproperties such as mechanical integrity during thermal cycling, heat transport andelectrical transport due to the inherent disparate properties such as coefficient ofthermal expansion (CTE), density and bonding strength. Multifunctional interfaces aredeveloped to bridge the desired properties and functionality. These interfaces arecomprised of an alloy of zirconium and copper which are common materialscompatible with electronics industry processes. A magnetron sputtering depositionsystem with dual deposition is utilized to perform the functional deposition. Thefunctionally varied layer is placed at the interface between a high coefficient ofthermal expansion material and a low CTE material and bridges the material propertydifferences. Materials selection is driven by comparing CTE differences, elasticmoduli and geometric averaging. Thermal cycling is performed to investigatemechanical integrity for extreme cycle ranges of order -55 °C to 300 °C. Additionallythin buffer zones using atomic layer deposition (ALD) are investigated for adhesionimprovement. Orthogonal to the mechanical properties, thermal and electronicproperties need to be maintained. Both thermal and electrical transport are investigatedfor the effect of the alloy gradient on them. Theoretical modelling is utilized to findthe proper alloy to simultaneously provide the best mechanical, thermal and electricalproperties.