Electrodeposition of copper thin films from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide
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Copper films are used as electrical contacts in printed circuit boards in view of their high electrical conductivity. The aim of the present work was to develop a method for the electrodeposition of high quality copper films from an ionic liquid-based electrolyte with low environmental and health impacts. The electrolyte investigated was copper(II) bis(trifluoromethylsulfonyl)imide (CuTFSI2) solutions in 1-methyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI). The Cu(II) → Cu(I) reaction in this electrolyte was quasi-reversible, with an activation energy of 12 kJ mol−1. Dense nano-crystalline copper films with particle sizes of 20 nm were easily obtained from CuTFSI2 solutions in EMIM-TFSI. The morphology of the copper films was independent of the deposition potential and time, possibly due to stable complexes in solution arising from the use of the ionic liquid and metallic salt with the same anion.
KeywordsElectrodeposition Ionic liquid Common ion Copper EMIM-TFSI
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