Electroless palladium plating bath

Abstract

A plating bath at least contains a palladium compound, a reducing agent, a complexing agent, and a stabilizer. The stabilizer is an organic compound in which a divalent sulfur compound is bonded to a compound with a heterocyclic structure, and the organic compound contains neither a thiol group nor a disulfide bond.

What is claimed is: 
     
         1 . An electroless palladium plating bath at least comprising:
 a palladium compound; a reducing agent; a complexing agent; and a stabilizer,   the stabilizer being an organic compound in which a divalent sulfur compound is bonded to a compound with a heterocyclic structure, the organic compound containing neither a thiol group nor a disulfide bond.   
     
     
         2 . The bath of  claim 1 , wherein
 the stabilizer has a concentration ranging from 0.01 mg/L to 10 mg/L.   
     
     
         3 . The bath of  claim 1 , wherein
 the heterocyclic structure is a nitrogen-containing heterocyclic structure or a sulfur-containing heterocyclic structure.   
     
     
         4 . The bath of  claim 3 , wherein
 the compound with the heterocyclic structure is at least one selected from the group consisting of imidazole, imidazolidine, imidazoline, oxadiazole, oxazine, thiadiazole, thiazole, thiazolidine, tetrazole, triazine, triazole, piperazine, piperidine, pyrazine, pyrazole, pyrazolidine, pyridine, pyridazine, pyrimidine, pyrrole, pyrrolidine, benzothiazole, benzimidazole, isoquinoline, thiophene, tetrahydrothiophene, pentamethylene sulfide, and a derivative thereof.   
     
     
         5 . The bath of  claim 1 , wherein
 the divalent sulfur compound is at least one selected from the group consisting of: thiadiazole, thiazole, thiazolidine, benzothiazole, thiophene, tetrahydrothiophene, methanethiol, benzenethiol, pentamethylene sulfide, dimethyl sulfide, methyl mercaptan, ethyl mercaptan, allyl mercaptan, thiopropionic acid, thioacetic acid, ethyl methyl sulfide, 1-propanethiol, 2-propanethiol, 2-aminoethanethiol, 2-mercaptoethanol, 4-mercaptopyridine, dimethyl sulfoxide, thiazolidine, S-methyl thioacetate, ethyl sulfide, methylpropyl sulfide, 1-butanethiol, thioglycolic acid, 2-(methylthio)ethanol, 3-mercapto-1-propanol, 2-methylthiazoline, cyclopentanethiol, 2-methyltetrahydrothiophene, pentamethylene sulfide, thiomorpholine, S-methyl thiopropionate, 3-mercaptopropionic acid, and a derivative thereof.