| 摘要 |
PURPOSE: Compositions and methods for electroless deposition of bright silver layers of uniform thickness are provided. CONSTITUTION: The immersion silver plating bath composition comprises one or more sources of silver ions, water, one or more complexing agents and one or more carboxylic acid-substituted nitrogen-containing heterocyclic compounds, wherein the bath is free of ammonia and ammonium ions, wherein the bath has a pH of more than or equal to 7, wherein the bath has a pH of more than or equal to 8.5, wherein the carboxylic acid-substituted nitrogen-containing heterocyclic compound is chosen from picolinic acid, quinolinic acid, nicotinic acid, fusaric acid, isonipecotic acid, nipecotic acid, pyridine dicarboxylic acid, piperazine carboxylic acid, pyrrole carboxylic acid and pipecolinic acid, wherein the carboxylic acid-substituted nitrogen-containing heterocyclic compound comprises a nitrogen-containing heterocyclic moiety chosen from pyridine, piperidine, piperazine, pyrrole, morpholine, pyrrolidine, triazole, and imidazole, wherein at least one complexing agent is a multidentate ligand, and wherein at least one complexing agent is chosen from cyanide, pyridine; amino acids having from 2 to 10 carbon atoms; polycarboxylic acids; amino acetic acids; pyridine carboxylic acid and pyridine dicarboxylic acid; alkylene polyamine polyacetic acids, polyamines; citrates; tartrates; N,N-di-(2-hydroxyethyl)glycine; gluconates; lactates; crown ethers; cryptands; polyhydric compounds; heteroaromatic compounds; thio-containing ligands and amino alcohols. The method of depositing a layer of silver on a substrate comprises the step of contacting a substrate having a layer of a metal that is less electropositive than silver with an immersion silver plating bath comprising one or more sources of silver ions, water, one or more complexing agents and one or more carboxylic acid-substituted nitrogen-containing heterocyclic compounds, wherein the bath is free of ammonia and ammonium ions.
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