FRACTAL STRUCTURE OF ELECTRODEPOSITED COPPER IN STOCHASTIC REGIMES AND ITS EFFECT ON PHASE FORMATION IN TIN REACTIONS
The Cu-Sn phase formation process is influenced by the structural structure of the copper layer and its roughness. The structural structure of the copper layer depends primarily on the technology of pre-treatment of copper plates.
The purpose of this work is to study the fractal dimension of the rough surfaces of copper layers, which are obtained as a result of the action of stationary and non-stationary regimes of electrodeposition of copper on copper plates. Copper coatings obtained by different regimes of electrodeposition were examined using a scanning electron microscope. In the course of the work, the fractal structure of electrodeposited copper layers after the solid-state reaction of copper with tin was analysed. The electrodeposited copper samples were immersed then briefly in molten tin and subjected to long-term solid-state annealing. As a result, the features of the fractal structure of the interface of copper layers before and after the solid-state reaction, depending on the regime of copper electrodeposition, were identified.
The influence of the structure of copper layers obtained under different regimes of electrodeposition - stationary, reverse impulse and stochastic on the result of solid-phase reactions with tin was compared. Stochastic modes of electrodeposition were obtained on the basis of the Chua random oscillation generator model with two stationary points. The stationary states were selected from the analysis of the polarization curve according to the conditions of the electrodeposition. As a result, it was shown that copper electrodeposition onto copper plates in stochastic modes leads to the formation of rough surfaces with fractal dimension. It is shown that the fractal dimension of the copper interface before and after the solid-state reaction depends on the regime of electrodeposition and characterizes the features of the roughness of the obtained interfaces. It is established that under stochastic regimes of electrodeposition, the obtained fractality of copper interface is quite significant and changes slightly after solid-state reaction with tin, unlike the use of stationary mode of electrodeposition with high overpotential.
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