Non-Stationary Electrolysis of a Tin-Copper Alloy

Abstract

Electrochemical coatings with a tin-copper alloy were obtained by the method of non-stationary electrolysis. The influence of the parameters of the pulsed-reversed currents (duty cycle, frequency, ratio of the duration of the forward and reverse pulses) on the kinetics of the process, structure, composition, functional and protective properties of deposits has been established. Pulsed electrolysis makes it possible to shift the coprecipitation potentials of alloy metals, expand the limits of the currents used, and form deposits at their high instantaneous values. The copper content in the coatings obtained on the unipolar pulsed current varies in the range of 3.31–4.77 wt.%, and on the pulse-reversed 1.59–1.69 wt.% (2.87 wt.% at direct current). Deposition on pulsereversed currents makes it possible to increase the solder spreading coefficient from 96.38 to 98.20 % and reduce the value of the contact electrical resistance of the coatings from 2.0133 to 1.5067 mOhm compared to the deposits obtained with the direct current. Coatings obtained on the pulsed current with the frequency of 10 Hz and the duty cycle of 3.33 with a copper content in an alloy close to eutectic, have a high coefficient of solder spreading and low contact resistance and are recommended for use in radio and microelectronic equipment for soldering movable and fixed electrical contact connections.

Keywords

• electrochemical coatings
• tin-copper alloy
• non-stationary electrolysis