[Zurück]

M. Kitzmantel:
"Wetting and infiltration behavior of copper and copper alloys on carbon nanofibers";
Betreuer/in(nen): C. Eisenmenger-Sittner; Festkörperphysik, 2008; Abschlussprüfung: 12.03.2008.

In electronic devices materials with a high thermal conductivity and a coefficient of thermal expansion matching to the ones of Si, GaAs or alumina are used as heat sinks, heat spreaders and substrates. Besides the high thermal conductivity a low coefficient of thermal expansion (CTE) is a crucial property for the long-term stability and reliability of the products. Today commonly used materials such as Mo-Cu, W-Cu, Kovar, Al/SiC, AlN or diamond exhibit several limitations in respect to limited thermal conductivity (Kovar), high density (Mo-Cu, W-Cu), bad machinability (Al/SiC, AlN) or high price (diamond). Within this feasibility study the wetting and infiltration behavior of copper and some copper alloys containing carbide forming elements such as Ti, Mo, Cr or B on carbon nanofibers were investigated. These additives promote wetting on the carbon surface. It is shown how carbon nanofibers (i.e. nanofilaments and nanotubes) can be used to reinforce a copper matrix. Several ways of producing metal matrix composites (MMC) with carbon nanoparticles as building blocks were investigated, including infiltrating carbon preforms with the metal matrix, powder metallurgical approaches and chemical coating of the nanofibers. Characterisation of the accomplished samples was done by measuring thermal prop-erties and studying the microstructure of the interface zone using scanning electron microscopy and EDX analysis. Hotpressing, conventional heating and microwave heating was carried out for fabricating the samples. The different producing routes show various problems addressed in this work.