Plating solution, conductive material, and surface treatment method of conductive material

Abstract

A plating solution including a copper salt, an organic phosphonic acid compound, and at least one compound or ions selected from an amine, α-amino acid, ammonium ions, carbonic acid ions, carboxylic acid ions, dicarboxylic acid ions, sulfuric acid ions, and thiosulfuric acid ions and a method of treating the surface of a conductive material using this plating solution.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a plating solution, a method of treating the surface of a conductive material using this plating solution, and a conductive material treated on its surface by this surface treatment method. [0003] 2. Description of the Related Art [0004] Permanent magnets, which is one type of conductive material, are being widely used for motors and actuators of various types of equipment. As such permanent magnets, Sm—Co-based rare earth permanent magnets obtained by powder metallurgy are being mass produced due to their relatively high performance. However, such Sm—Co-based rare earth permanent magnets have the problem of using as materials the expensive Sm and Co, so end up becoming high in cost. [0005] Among the rare earth, the smaller atomic weight rare earth elements such as cerium (Ce), praseodymium (Pr), and neodymium (Nd) are present more abundantly than samarium (Sm) and are relatively low...

AI Technical Summary

Benefits of technology

[0013] An object of the present invention is to provide a plating solution able to form a protective film superior in adhesion, corrosion resistance, and heat resistance on the surface of a magnet or other conductive material and able to stably form a protective film having a high adhesion and a good appearance even with repeated plating, a method of treating the surface of a conductive material using this plating solution, and a conductive material obtained by this method.

[0014] The inventors engaged in intensive studies to achieve the above object and as a result discovered that by adding a predetermined compound or ions to a plating solution including a copper salt and organic phonic acid compound, the above object can be achieved and thereby completed the present invention.

[0018] In the plating solution of the present invention, the content of the compound or ions is, converted to the compound or ions, preferably 0.01 to 2 mol / liter. If the content of the compound or ions is too low, the effect of the present invention ends up becoming small. On the other hand, if too great, uneven plating tends to easily occur.

[0024] The plating solution of the present invention contains a copper salt and an organic phosphonic acid compound, so for example when using the plating solution of the present invention and an anode containing copper to form a protective film comprised of copper on the surface of a conductive material, it is possible to form a protective film superior in adhesion and improve the corrosion resistance and heat resistance of the conductive material.

[0025] Further, the plating solution of the present invention contains, in addition to the copper salt and organic phosphonic acid compound, the predetermined compound or ions. For this reason, even if repeatedly plating, it is possible to stably form a protective film having a high adhesion and further a good appearance.

[0026] Further, the surface treatment method of the present invention uses the plating solution of the present invention and an anode containing copper. For this reason, the conductive material may be stably formed on its surface with a protective film having a high adhesion and further a good appearance.

Problems solved by technology

However, such Sm—Co-based rare earth permanent magnets have the problem of using as materials the expensive Sm and Co, so end up becoming high in cost.

However, such permanent magnets include as main ingredients easily oxidizable rare earth elements and iron, so have relatively low corrosion resistances, are degraded in performance, and have problems in production variance.

However, this publication uses copper cyanide for the plating bath, so has the problems of a weak adhesion between the magnet body and the plating film and a lack of reliability.

However, this publication uses a copper pyrophosphate plating bath, so has the problem that the R—Fe—B-based permanent magnet with the greater tendency for ionization than copper dissolves by immersion and the R—Fe-—B-based permanent magnet ends up being corroded at its surface.

However, a Nd—Fe—B-based permanent magnet suitably used as a rare earth magnet has the property of hydrogen embrittlement, so ends up breaking due to the hydrogen gas produced by the electroless Cu plating and therefore a plating film with good pore sealability cannot be obtained.

However, in this Japanese Patent No. 3614754, there is the problem that in the actual production process, if using the same plating solution for repeated plating, the plating solution ends up deteriorating and the color of the Cu changes from a skin color to a dark brown color.

This has become a cause of higher cost,