The optimal composition of a polyligand ammonium-chloride-fluoride electrolyte and optimized electrolysis conditions for the deposition of functional tin-nickel alloy coatings are proposed. A tin-nickel alloy with a tin content of 65 wt.% and a nickel content of 35 wt.% was found to be the most promising alloy for replacing gold coating in microelectronics. It is shown that the obtained coatings are suitable for soldering using lowtemperature solders and acid-free fluxes, and for ultrasonic spot welding.