Method for forming electrical traces on substrate

A method for forming electrical traces on a substrate, the method comprising:

• printing an ink pattern on the substrate using an ink, the ink comprising an aqueous medium containing silver ions and a heat sensitive reducing agent, the heat sensitive reducing agent being capable of reacting with the silver ions at a temperature in the range from approximately 50° C. to approximately 250° C., the aqueous medium comprising water, a water-soluble silver salt, and a water-soluble organic solvent, the weight percent of the water-soluble organic solvent being in the range from 4%-50%, the molar concentration of the silver salt being in the range from 0.02 mol/L-2 mol/L, and the weight percent of the heat sensitive reducing agent being in the range from approximately 0.5% to approximately 0.87%;
• heating the ink pattern to reduce silver ions into silver particles thereby forming semi-finished traces on the substrate;
• and
• forming a metal overcoat on the semi-finished traces by electroless plating thereby obtaining patterned electrical traces on the substrate.