SKM 2023 – scientific programme

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DS: Fachverband Dünne Schichten

DS 12: Poster

DS 12.29: Poster

Wednesday, March 29, 2023, 17:00–19:00, P3

Determining the brazeability of copper surfaces via spectroscopic ellipsometry — •Friedrich Bürger, Lienhard Wegewitz, and Wolfgang Maus-Friedrichs — Clausthal Centre of Material Technology, Clausthal University of Technology, Agricolastr. 2, 38678 Clausthal-Zellerfeld

In Brazing, surface conditions play a fundamental role in determining the joint strength. Not all changes of the surface, like thick oxide layers or oil films, may be immediately apparent and therefore will only be noticed when the brazing process failed. Since most methods of determining brazeability work by performing a brazing process and evaluating the results they can only be performed on samples. This does not represent variation of surfaces within a batch of material. To fill this gap a nondestructive method to determine brazeability is needed. Spectroscopic ellipsometry (SE) is an optical measurement method commonly used to characterize the optical properties of surfaces and thin films. To evaluate if SE can be used to distinguish surface states of copper surfaces that negatively impact the joint strength, different surfaces were prepared. The selected surface states were a reference condition, ground surfaces, oxidized surfaces and different oil films on the reference surface. Those surfaces were characterized by confocal laser scanning microscopy (CLSM) and X-Ray photoelectron spectroscopy (XPS) to determine their morphology and chemical composition. SE-measurements were performed subsequently. Except for the ground states all surfaces showed distinct features in their SE-spectra, suggesting identification via SE is possible.