SELECTIVE COATING OF EXPOSED COPPER ON SILVER-PLATED COPPER
Silver-plated copper particles in which any exposed copper not plated with silver are coated with a polymer or with a chelating compound capable of preventing oxidation of the exposed copper. A method for preventing oxidation of any exposed copper on silver-plated copper particles and for improving the conductivity of silver-plated copper particles comprises coating a polymer or a copper-chelating compound onto the exposed copper on the silver-plated copper particles.
1 . Silver-plated copper particles in which any exposed copper not plated with silver is coated with a polymer or with a chelating compound capable of preventing oxidation of the exposed copper.
2 . A method for preventing oxidation of any exposed copper on silver-plated copper particles comprising forming a polymer on, or coating a copper-chelating compound onto, the exposed copper on the silver-plated copper particles.
3 . The method according to claim 2 in which a polymer is formed on the exposed copper on the silver-plated copper particles comprising coating monomers that will polymerize in the presence of copper or copper ions onto the silver-plated copper particles, and allowing the monomers to polymerize.
4 . The method according to claim 3 in which the polymer is polyaniline.
5 . The method according to claim 3 in which the polymer is an acrylate, a methacrylate, or a maleimide.
6 . The method according to claim 3 in which the polymer is the 1,2,3-triazole reaction product of an azide and an alkyne.
7 . The method according to claim 3 in which the polymer is a polymerized epoxy, oxetane, vinyl ether or a mixture of them.
8 . The method according to claim 2 in which a chelating compound is coated onto the exposed copper on the silver-plated copper particles comprising coating a chelating compound having a stronger binding force to copper than to silver onto the silver-plated copper particles.
9 . The method according to claim 8 in which the chelating compound is selected from the group consisting of oximes, azoles, amines, amides, amino acids, thiols, phosphates and xanthates.
10 . A method for improving the conductivity stability of silver-plated copper particles comprising forming a polymer on, or coating a copper-chelating compound onto, the exposed copper on the silver-plated copper particles.
11 . The method according to claim 10 in which a polymer is formed on the exposed copper on the silver-plated copper particles comprising coating monomers that will polymerize in the presence of copper or copper ions onto the silver-plated copper particles, and allowing the monomers to polymerize.
12 . The method according to claim 11 in which the polymer is polyaniline.
13 . The method according to claim 11 in which the polymer is an acrylate, a methacrylate, or a maleimide.
14 . The method according to claim 11 in which the polymer is the 1,2,3-triazole reaction product of an azide and an alkyne.
15 . The method according to claim 11 in which the polymer is a polymerized epoxy, oxetane, vinyl ether or mixture of them.
16 . The method according to claim 10 in which a chelating compound is coated onto the exposed copper on the silver-plated copper particles comprising coating a chelating compound having a stronger binding force to copper than to silver onto the silver-plated copper particles.
17 . The method according to claim 16 in which the chelating compound is selected from the group consisting of oximes, azoles, amines, amides, amino acids, thiols, phosphates and xanthates.