<p>The synergistic effect of p-phenylenediamine (PDA), thiourea (TU), and hexamine (HA) additives was studied in a thiosulfate-based bath on the quality of silver coated copper pin connector. The composition of bath was 40&#xa0;g L⁻¹ AgNO₃, 40&#xa0;g L⁻¹ Na₂S₂O₅, 200&#xa0;g L⁻¹ Na₂S₂O₃·5H₂O, pH 5.6, and current density 12.5&#xa0;mA cm⁻². The used additives were optimized at amounts of 0.8, 0.2, and 0.2&#xa0;g L⁻¹, respectively, for PDA, TU, and HA. The silver coated copper showed an electrical resistance of 0.032 ohm, roughness of 0.048 micron, and thickness of 49 microns in optimized conditions. The X-ray diffraction patterns, scanning electron microscopy – energy dispersive spectroscopy, Tafel plots, and electrochemical impedance spectroscopy (EIS) techniques were used to characterize the silver coated copper. The results showed that the quality of silver layer increased in the presence of the proposed additives through creating uniformity the surface, reducing the size of silver crystals, increasing adhesion, and reducing the porosity of the coating. Increasing of resistance to corrosion of silver layer was confirmed by results of Tafel polarization curves, Nyquist diagrams in EIS technique, and salt spray test. The corrosion rate of a copper pin connector was reduced from 4.95 to 2.34 µA cm⁻² and corrosion potential was shifted from −592 to −239 mV by coating of a silver layer.</p> Graphical Abstract <p></p>