JPS61195985A - Lusterless high-velocity silver plating liquid - Google Patents

Abstract

PURPOSE:To obtain the lusterless silver plating in 50-90A/dm<2> high current density by containing one and more kinds of a formalin condensate of aromatic sulfonic acid and its salt, aromatic carboxylic acid and its salt, fatty polycarboxylic acid and its salt. CONSTITUTION:An organic additive consisting of the following substance is contained in a lusterless silver plating soln. which is one and more kinds of a formalin condensate of aromatic sulfonic acid and its salt, aromatic carboxylic acid and its salt, fatty polycarboxylic acid and its salt. The weight to be added of the organic additive for the silver plating soln. is regulated to 5mg-5g/l.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a silver plating solution, and more specifically, to a matte high-speed silver plating solution for N-depositing a matte silver film.

(Prior art) Silver plating technology is widely used for silver plating electronic and electrical parts such as lead frames and connectors, but when silver plating these parts, high-speed plating is recommended from an economical standpoint. This is advantageous and has become mainstream.

^ Speed silver plating can be achieved by increasing the current density, increasing the liquid temperature, increasing the metal ion concentration, and increasing the flow rate of the plating solution, as well as adding metal salts such as selenium to the silver plating solution. By adding these metal salts, the deposited silver film becomes glossy.

(Problems to be solved by the invention) However, depending on the characteristics of the silver plating required,
It may not be possible to add metal salts such as selenium. In addition, from the viewpoint of physical properties such as bondability and solderability of the precipitated silver film, matte precipitated silver is desirable, but with conventional silver plating solutions, such matte silver plating is difficult to achieve with low current. It can only be obtained at a density (approximately 30 A/dd or less) and has the drawback of lacking speed.

(Means for Solving the Problems) In view of the above-mentioned shortcomings of the prior art, the present invention has been made to conduct research and study in order to develop a matte high-speed silver plating solution capable of depositing matte silver at high current density. As a result, the inventors learned that matte precipitated silver could be obtained at high current density by adding an organic additive to the silver plating solution, and completed the present invention.

Therefore, an object of the present invention is to provide a matte high-speed silver plating solution that can produce a matte precipitated silver film at a high current density.

The matte high-speed silver plating solution of the present invention contains at least one member selected from the group consisting of formalin condensates of aromatic sulfonic acids and salts thereof, aromatic carboxylic acids and salts thereof, and aliphatic polycarboxylic acids and salts thereof. This relates to a structure characterized by containing an organic additive consisting of a substance.

As described above, the matte high-speed silver plating solution of the present invention contains, as organic additives, formalin condensates of aromatic sulfonic acids and their salts, aromatic carboxylic acids and their salts, and aliphatic polycarboxylic acids and It contains at least one substance selected from the group consisting of salts thereof.

Examples of formalin condensates of aromatic sulfonic acids or salts thereof include naphthalene sulfonic acid formalin condensates, and these naphthalene sulfonic acid formalin condensates are obtained as a mixture of isomers having different degrees of condensation and structures, The naphthalene ring may also have a hydrocarbon group, including alkylated naphthalene sulfonic acid formalin condensates. These condensates are often commercially available as sodium salts, but acid forms and other soluble salts or mixtures thereof can also be used.

Examples of aromatic carboxylic acids or salts thereof include carboxylic acids such as aromatic monocyclic hydrocarbons, aromatic polycyclic hydrocarbons, and derivatives thereof, and salts thereof, such as benzoic acid, naphthoic acid, bamoic acid, etc. Salt is an example.

The aliphatic polycarboxylic acid or its salt has 5 to 20 carbon atoms and is obtained as a mixture of isomers having different numbers of carboxyl groups and structures. These aliphatic polycarboxylic acids having 5 to 20 carbon atoms or their salts are often commercially available as sodium salts, but they can also be used in acid form, other soluble salts, or mixtures thereof. can.

Further, other components of the matte high-speed silver plating solution of the present invention may be those obvious to those skilled in the art. For example, the main components are silver compounds such as potassium silver cyanide and sodium silver cyanide, and conductive salts such as citrate, phosphate, birophosphate, sulfate, nitrate, and sulfamate, and other buffering agents. and a low cyanide bath that can contain a chelating reagent, a pH adjusting agent, and the like. Furthermore, an alkaline cyanide bath containing cyanides such as silver cyanide and potassium cyanide as main components can also be used.

The amount of the above-mentioned organic additive added to the plating solution can be varied over a wide range, but depending on the characteristics of the deposited silver film obtained and the economical efficiency of the silver plating solution, the amount of the organic additive should be between 5η/β and 5η/β. Preferably, it is 59/β. That is, as the amount added becomes less than 5Rg/i, it becomes increasingly difficult to obtain a matte silver film, while as the amount exceeds 59/12, the precipitated silver film tends to discolor and is also economically disadvantageous. becomes.

(Function) The organic additive contained in the silver plating solution of the present invention imparts mattness to the precipitated silver film and also imparts high-speed plating properties to the plating solution.

(Examples and Comparative Examples) Hereinafter, the present invention will be explained with reference to Examples thereof, and
Comparative examples conducted in connection with the present invention will also be listed.

1 suit ■ Potassium silver cyanide 120g/l Potassium phosphate 40g
/β, naphthalene sulfonic acid formalin condensate (sodium salt) 50η/1, pHwA adjustment reagent 1. :J
: High-speed plating (jet plating) was performed using a tamping solution with a pH of 8.2 and a temperature of 65° C. and a platinum plate as an anode.

A good matte silver film was obtained when the N flow density was in the range of 60 to 80 A/dd. The obtained silver film has bonding properties,
Physical properties such as solderability and heat resistance were good.

15■1 Potassium silver cyanide 120g/β, potassium phosphate 40
g/f, naphthalene sulfonic acid formalin condensate (sodium salt) 500 ay/J2, using a tightening solution with a pH of 8.2 using a pH adjusting reagent and a temperature of 65°C, and using a platinum plate as an anode at high speed. Plating (jet plating) was performed.

A good matte silver film was obtained at a current density of 50 to 80 A/dd. The obtained silver film had good physical properties such as bondability, solderability, and heat resistance.

Potassium silver dianide 120g/i, potassium phosphate 40g/i
g/12, using a tightening solution containing naphthalene sulfonic acid formalin condensate (sodium salt) 19/n, adjusted to pH 8.2 and temperature to 65°C with a pH 1l adjusting reagent,
High-speed plating (jet plating) was performed using a platinum plate as an anode.

A good matte silver film was obtained at a current density in the range of 50 to 90 A/dm. The obtained silver film had good physical properties such as bondability, solderability, and heat resistance.

U Seal A Potassium silver cyanide 12 (1/f, potassium phosphate 40
9/12, using a tightening solution containing 3g/e of naphthalene sulfonic acid formalin condensate (sodium salt), adjusting the pH to 8.2 with a 3l pH adjustment reagent, and adjusting the temperature to 65°C, using a platinum plate as an anode. Speed plating (jet plating)
I did it.

A good matte silver film was obtained at a current density in the range of 50 to 90 A/dm. The obtained silver film had good physical properties such as bondability, solderability, and heat resistance.

111 potassium silver cyanide 1'20 SF/f, potassium phosphate 409/It, sodium benzoate 1g/β
High-speed plating (jet plating) is performed using a plating solution containing E)H of 8.2 and a temperature of 65° C. using a pH adjusting reagent, and using a platinum plate as an anode.

Ta.

A good matte silver film was obtained at a current density in the range of 50 to 70 A/d-. The obtained silver film had good physical properties such as bondability, solderability, and heat resistance.

Support i ■ Potassium silver cyanide 120g/J, potassium phosphate 40
g/l aliphatic polycarboxylic acid sodium salt (carbon number 5~
20) Using a plating solution containing 5ooIIy/i, with a DH of 8.2 and a temperature of 65°C using a pH adjustment reagent,
High-speed plating (jet plating) was performed using a platinum plate as an anode.

A good matte silver film was obtained at a current density in the range of 50 to 90 A/dTIt. The obtained silver film had good physical properties such as bondability, solderability, and heat resistance.

Ward Kasa 1 Potassium silver cyanide 12097β, Potassium phosphate 40
1) 8.g/11.
2. High-speed plating (jet plating) was performed using a tamping solution at a temperature of 65° C. and using a platinum plate as an anode.

A matte silver film was obtained at a current density of 10 to 30 A/d. Compared with Examples 1 to 6, the current density range in which a matte silver film was obtained was extremely narrow and the current density was low, making it impossible to use at high current densities and clearly inferior in high speed performance.

(Effects) In the present invention, matte precipitated silver can only be obtained at a low current density of about 30 A/dd or less with a conventional silver plating solution, but by coexisting with the above additives, a matte precipitated silver can be obtained at a current density of 50 to 90 A/dd. A matte silver film can be obtained at a high current density, and the physical properties such as bondability, solderability, and heat resistance of this deposited film are good, and the matte silver film can be obtained at a low current density using a conventional silver plating solution. No difference is observed in the physical properties of the silver film.

Claims (2)

[Claims] (1) Contains an organic additive consisting of at least one substance selected from the group consisting of formalin condensates of aromatic sulfonic acids and their salts, aromatic carboxylic acids and their salts, and aliphatic polycarboxylic acids and their salts. A matte high-speed silver plating solution that is characterized by: (2) The content of the organic additive in the silver plating solution is 5 mg/l
The matte high-speed silver plating solution according to claim 1, characterized in that the concentration is from 5 g/l to 5 g/l.