Electroless gold plating bath

Abstract

The electroless gold plating bath includes a gold sulfate, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, hydrazide, 3-hydro-2-naphtboic hydrazide benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, and isopropylhydrazine hydrochloride.

What is claimed is: 
     
         1 . An electroless gold plating bath, comprising a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds,
 the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,1-dimethyhydrazine, 2-hydrazinobenzothiazole, acetohydrazide, 2-hydroxyethylhydrazine, ethoxycarbonylhydrazine, methoxycarbonylhydrazine, phenylhydrazine-4-sulfonic acid, and benzohydrazide.   
     
     
         2 . The electroless gold plating bath of  claim 1 , wherein
 the ascorbic acid compounds are at least one selected from the group consisting of ascorbic acid, sodium ascorbyl phosphate, magnesium ascorbyl phosphate, and ascorbic acid 2-glucoside.   
     
     
         3 . The electroless gold plating bath of  claim 1 , wherein
 a concentration of the hydrazine compounds is in a range of 0.5 g/L to 15 g/L and a concentration of the ascorbic acid compounds is in a range of 1 g/L to 20 gL.   
     
     
         4 . The electroless gold plating bath of  claim 1 , wherein
 a mass ratio of gold in the gold sulfite to the thiosulfate is in a range of gold: thiosulfate=1: 0.5 to 1: 10.   
     
     
         5 . The electroless gold plating bath of  claim 1 , further comprising:
 an anti-corrosion agent and an amine-based complexing agent, wherein   a mass ratio of the anti-corrosion agent to the amine-based complexing agent is in a range of anti-corrosion agent: amine-based complexing agent=1: 0.5 to 1: 10.