[Zurück]

P. Kijamnajsuk, M. Chirtoc, N. Horny, J. Pelzl, D. Schäfer, C. Eisenmenger-Sittner:
"Experimental Evidence Of Laterally Inhomogeneous Thermal Interface Resistance In Copper Coated Carbon Samples";
Vortrag: 16th International Conference on Photoacoustic and Photothermal Phenomena (16th ICPPP), Merida, Mexico; 27.11.2011 - 01.12.2011.

Thermal interfaces are essential for the application of modern composites in electronic devices. In this work the heat transfer in copper-carbon flat model systems was studied by frequency dependent photothermal radiometry (PTR). A novel approach which relies on the frequency dependence of the photothermal signal phase and amplitude at intermediate frequencies was used to determine the thermal interface resistance between the substrate and the metallic coating [1]. The samples consist of Cu- films of about 1 µm thickness deposited by magnetron sputtering on Sigradur. Particular interest was devoted to the influence of thin bonding layers and of a subsequent heat treatment on the thermal interface resistance in the CuC systems. The photothermal measurements on CuC were complemented structural, chemical and mechanical analysis of the coated samples. General trends observed for a large number of samples are the correlations between the thermal interface conductance and adhesion strength [2]. For some samples, however, the frequency dependence of the PTR-signal could not be fitted by the assumption of a unique thermal interface resi-stance. For these samples we made a detailed comparative experimental and theoretical study of of the thermal parameters between samples of the same production series. The experimental data were analysed in the frame of heat diffusion equation for 1D- and 3D-heat transport. For particular conditions the changes are found to be independent on the dimensionality of the heat diffusion problem. Fig.1 shows the experimental data (symbols) compared with the theory (full lines). The theoretical curves were obtained by assuming that a small part of the film area (mostly a few percent) has an up to one order of magnitude higher thermal interface resistance than the remaining area of the Cu-film. The size and the interface resistance of the distorted areas can be deduced from the position and height of the extrema.
REFERENCES
[1] P. Kijamnajsuk, F. Giuliani, M. Chirtoc, N. Horny ,J. Gibkes, S. Chotikaprakhan, B. K. Bein and J. Pelzl, J. Of Physics, Conf. Ser., Vol.214, 012053 (2010).
[2] D. Schäfer, C. Eisenmenger-Sittner, Mihai Chirtoc, P. Kijamnajsuk, N. Kornfeind, H. Hutter, E. Neubauer, M. Kitzmantel; Surface and Coatings Technology, 205 (2011) 3729-3735.
(a)On leave from Institute of Experimental Physics, Ruhr-University, Bochum, Germany