JPS5824508B2 - Glossy palladium plating bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition of a plating bath that enables palladium plating with excellent gloss.

Palladium plating has good corrosion resistance and high hardness, so it is strongly desired that it be glossy and resistant to discoloration, especially for decorative purposes in addition to electrical applications.

Conventional general palladium plating is prone to discoloration and quickly turns into a characteristic dark color, which makes it look unsightly, making it unsuitable for decorative purposes.

Conventional bright palladium plating baths are used for the purpose of adjusting the pH of the palladium source and stabilizing the palladium complex salt, or as a buffering agent (7
This was often done using a complex system in which various types of brighteners were added to the solution using ammonia water.

However, in such a system, as the plating process progresses, brownish precipitates are deposited near the anode plate, resulting in entrained electrodeposition, which deteriorates the electrodeposition condition of the object to be plated, causing deterioration in gloss and appearance, etc. adversely affect.

Ammonia also causes a deterioration of the working environment due to its unique strong odor.

Furthermore, this bath decomposed within a few days, resulting in poor bath stability.

The object of the present invention is to provide a new plating bath that solves these problems.

The present invention uses dichlorodiamine palladium in an amount of 1 to 20 if/l in terms of palladium, and sodium hydroxide in an amount of 1 to 20
f/7 and saccharin alkali 1 to i o o y7
Provided is an aqueous palladium plating bath consisting of t.

When performing palladium bright plating, the selection of brightener is generally a problem.

For example, many compounds are disclosed in JP-A-54-67528.

It is known that these various organic and inorganic compounds are used alone or in complex combinations as brighteners, and that they affect the gloss and strength of plating.

In conventional systems, ammonia water is used as a pH adjuster or palladium solution, and palladium in the solution is dissolved as an ammonia complex salt (for example, Japanese Patent Publication No. 42-20164), and various ammonium salts, etc. are used as buffering agents. Sulfates, phosphates, sulfites, etc. are commonly added.

Furthermore, the bright plating bath (PL) is conventionally often carried out at an alkaline pH of about 8 to 12, and both contain a large amount of ammonium ions.

This ammonium ion has been positioned as an important element that increases the stability of palladium ammonia complex salts.

The present invention has realized a palladium plating bath that enables palladium plating with excellent gloss by using an extremely simple system that requires three components in place of such a complicated plating bath system.

That is, the plating bath of the present invention uses dichlorodiamine palladium as a palladium source, in terms of palladium amount of 1 to 201/).
(preferably 5-10?/l) containing 1-20 f? of sodium hydroxide. /l (preferably 5-10 f/
/! ) is dissolved in an aqueous plating bath with a strongly alkaline pH, preferably at approximately pH 13 to 14.

The first advantage of the bath of the present invention is that the conventional plating bath does not contain any ammonia (except for the ammonia contained in the palladium source), which eliminates the problem of precipitation near the anode plate and deteriorates the plating. is to be prevented;
The second advantage is that the stability of the bath is improved, allowing stable operation over a long period of time, and the third advantage is that the ammonia odor is greatly reduced.

As a brightening agent, a saccharin alkali such as saccharin sodium or saccharin potassium is used in an amount of 1 to 1001/l (preferably 20 to 50 y7t).
The advantages of this are that the plated layer has excellent gloss, is dense, has excellent corrosion resistance, and can be sufficiently thick from 5μ or more to 7μ without cracking.

The palladium plating of the present invention shows good results in terms of discoloration, which is a drawback of conventional palladium plating, and has good discoloration resistance in an atmosphere of ammonia or sulfur dioxide gas.

In addition, plated objects plated with this bath have good solder wettability (plating with a bath with a wetting angle of 40 to 45 times can be applied to copper, brass, gold, silver, rhodium, cobalt, nickel, etc.). Can be applied to ammonia gas and sulfur dioxide gas.

It is suitable as a finishing plating to protect from the like.

The bath temperature is 30 to 60°C, but this temperature is not necessarily limited, and the upper limit is generally specified from the viewpoint of heat resistance of equipment such as vinyl chloride, and the lower limit is generally specified from the viewpoint of processing speed, etc. It is something that

The current density is preferably approximately 0.5 to 1.5 A/di, but
Again, this is a general range.

However, if the current density is too large, there is a risk that harm may occur due to the generation of hydrogen gas.

Generally, it is preferable to carry out stirring during plating current application.

Examples of the present invention are shown below.

Example dichlorodiamine palladium (Pd (NH3')2C
12) Pd equivalent amount 6 f/1 Sodium hydroxide 12.51/l Saccharin sodium 20 f/7O (C6H4<>N Na 02 pH 13 The above bath was heated at a temperature of 50°C and a current density of IA/drn' with a cathode rocker. 2. While stirring, use a brass plate as the object to be plated.
Plated for 5 minutes.

As a result, a shiny precipitate with a thickness of 5 μm was obtained.

The corrosion resistance of this palladium plating was examined by aeration in an ammonia atmosphere for 24 hours, but no discoloration was observed.

Claims (1)

[Claims] 1 to 20 fI/7.1 in palladium equivalent amount of dichlorodiamine palladium. Sodium hydroxide 1-20 f/
an aqueous palladium electroplating bath consisting of 1-100y7t of saccharin alkali and 1-100y7t of saccharin alkali.