Electrodeposited Sn-Cu-Ni alloys as lead-free solders on copper substrate using deep eutectic solvents : The influence of electrodeposition mode on the morphology, composition and corrosion behaviour

• In this work we present the pulsed current (PC) electrodeposition of Sn-Cu-Ni alloy as lead-free solder candidate, from choline chloride – ethylene glycol eutectic mixtures (1:2 molar ratio) onto copper metallic substrates. Electrolytes containing Sn2+, Cu2+ and Ni2+ salts in the selected deep eutectic solvent have been considered. The effect of the applied frequency of PC on the morphology, composition and melting point of the alloy is discussed and compared to the ones obtained using direct current (DC) plating mode. A refinement of the grain size and lower melting temperature of the alloy were noticed when pulsed current was applied. A comparative analysis of the electrochemical corrosion behaviour at macro- and micro- scale has been performed in 0.5 M and 0.1 M NaCl solutions involving potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode (SVET) techniques. Furthermore, an analysis after 96 h of exposure to salt mist test simulating a corrosive attack in harsh environment is presented, too. The obtained results showed enhanced corrosion resistance of the ternary alloys electrodeposited under PC conditions (the best for 1.67 Hz frequency) as compared to those using DC. Additionally, Raman spectroscopy evidenced the presence of tin oxi/hydroxy chloride and tin oxides as surface corrosion products. A corrosion mechanism has been proposed.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Corrosion behaviour

Deep eutectic solvents

Electrodeposition

Sn-Cu-Ni ternary alloy

SVET

Copper alloys

Copper corrosion

Corrosion resistance

Corrosion resistant alloys

Corrosive effects

Electrochemical corrosion

Electrochemical impedance spectroscopy

Electrodes

Ethylene

Ethylene glycol

Eutectics

Lead-free solders

Melting point

Molar ratio

Morphology

Nickel alloys

Organic solvents

Sodium chloride

Substrates

Tin alloys

Tin oxides

Choline chloride

Copper substrates

Electrodeposition mode

Morphology behavior

Pulsed currents

Pulsed-current electrodeposition

Scanning vibrating electrodes

Ternary alloys

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