Rolf Schumacher

Formation and properties of UPD copper deposits on polycrystalline platinum electrodes

Abstract Formation and properties of UPD Cu deposits on polycrystalline Pt electrodes have been studied in sulfuric acid with various additions of chloride, thiourea (TU), acetonitrile (ACN) and polyethylenglycole (PEG). The experimental set-up combines coulometry, in situ microgravimetry and in situ differential reflectance spectroscopy. This set-up allows the simultaneous examination of the same electrode by recording cyclic voltammograms, frequency shifts of a mass sensitive oscillating quartz crystal and the reflected light intensities of a coherent light source from the surface. The latter technique uses a HeNe laser which operates at a wavelength of 543 nm and was focused perpendicularly onto the Pt surface. The observed surface coverages θ, the electrosorption valencies γ, and the optical properties ΔI I of UPD copper adsorbates on Pt shed some light on their charge and size distribution and the adsorbate-substrate interaction.

Morphology and Stability of Electrochemically Generated Copper Layers: The Effect of Electron Transfer and Nucleation Kinetics

This paper reports on a method for in‐situ observation of the morphology and stability of electrochemically generated metal layers. This information is obtained by comparing topographical and kinetic data. The method is based on coulometric, microgravimetric and optical measurement performed in situ on vertically growing electrodes. Measurements are obtained simultaneously from the same surface area.

The influence of organic additives on the thickness distribution of tubular metallized through-holes

Abstract Through-hole plating capability was examined for process electrolytes made up with various organic additives. Tafel plots were obtained from cyclic voltammetry using the rotating-disc technique. The levelling capability of the electrolytes was obtained from coulometry and in situ microgravimetry in combination with optical microscopy, the throwing power for through-hole plating from the thickness ratio center of hole-plane surface outside the hole. It was shown that a high throwing power correlates with a low levelling capability. The results shed some light on the inhibiting character of the process electrolytes used.