Electroless gold plating bath

Patent metadata

Field	Value
Publication number	US-10975475-B2
Application number	US-202016806328-A
Country	US
Kind code	B2
Filing date	Mar 2, 2020
Priority date	Mar 6, 2019
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

The present invention provides an electroless gold plating bath having excellent plating bath stability without containing a cyanide compound under long term plating bath heating time. An electroless gold plating bath of the present invention solving above problems includes: a water-soluble gold salt; a reducing agent; and a phosphine compound represented by a following formula (1)

wherein R 1 , R 2 , and R 3 represent identically or differently either a phenyl group, or an alkyl group having 1 to 5 carbons, and at least one of the phenyl group or the alkyl group is substituted by a sulfonate group or its salt, a cyano group, or a carboxy group or its salt.

First claim

The invention claimed is:

1. An electroless gold plating bath, comprising:
a water-soluble gold salt;
a reducing agent; and
a phosphine compound represented by a following formula (1)

wherein R 1 , R 2 , and R 3 represent identically or differently either a phenyl group, or an alkyl group having 1 to 5 carbons, and at least one of the phenyl group or the alkyl group is substituted by a sulfonate group or its salt, a cyano group, or a carboxy group or its salt.

2. The electroless gold plating bath according to claim 1 , wherein the electroless gold plating bath contains no cyanide compound as an additive.

3. The electroless gold plating bath according to claim 1 , wherein the electroless gold plating bath has a pH of 5 to 10.

4. The electroless gold plating bath according to claim 1 , wherein the reducing agent is formaldehyde and/or formaldehyde bisulfate adduct in combination with at least one of the following amine compounds
R 1 —NH—C 2 H 4 —NH—R 2   (1)

R 3 —(CH 2 —NH—C 2 H 4 —NH—CH 2 ) n —R 4   (2)

wherein in (1) and the formula (2),
R 1 , R 2 , R 3 and R 4 represent —OH, —CH 3 , —CH 2 OH, —C 2 H 4 OH, —CH 2 N (CH 3 ) 2 , —CH 2 NH (CH 2 OH), —CH 2 NH (C 2 H 4 OH), —C 2 H 4 NH (CH 2 OH), —C 2 H 4 NH (C 2 H 4 OH), —CH 2 N (CH 2 OH) 2 , —CH 2 N (C 2 H 4 OH) 2 , —C 2 H 4 N (CH 2 OH) 2 or —C 2 H 4 N (C 2 H 4 OH) 2 ,
R 1 , R 2 , R 3 and R 4 may represent are the same or are different, and
n is an integer of 1 to 4.

5. The electroless gold plating bath according to claim 1 , wherein the water-soluble gold salt is gold cyanide salt and/or gold cyanide.

Assignees

• Uemura Kogyo Kk

Inventors

• Kaneko Yohei
• Nishimura Naoshi
• Maeda Tsuyoshi
• Tanabe Katsuhisa

Classifications

• C23C18/44 Primary

  using reducing agents · CPC title