JP2020105573A - Electroless plating solution, plating film, plated article and forming method of plating film - Google Patents

Abstract

To provide an electroless plating solution capable of forming a plating film which is excellent in abrasion resistance with high rigidity, with excellent slidability, keeping excellent eutectoid and bath stability, and to provide a plating film formed by the electroless plating solution, a plated article having the plating film and a forming method of the plating film.SOLUTION: The electroless plating solution contains, as essential components, water soluble nickel compound, reductant, complexing agent, and silicon carbide, and contains polycarboxylic acid type polymer surface active agent and/or aromatic sulfonic acid formalin condensate or its salt. The electroless plating solution is characterized in that the obtained plating film has a phosphorous content of 0.1 to 4 mass%. There are also provided: a plating film formed by the electroless plating solution; and a forming method of the plating film including a process for forming the plating film by causing a plating object to contact with the plating solution.SELECTED DRAWING: None

Description

The present invention relates to an electroless plating solution, a plating film, a plated product, and a method for forming a plating film.

2. Description of the Related Art Conventionally, a plating film is formed in various fields such as a printed wiring board forming an electronic component and the surface of a mechanical device. In particular, a plating film formed by a plating solution containing fine particles is formed on sliding parts such as shafts, cylinders and bearings of mechanical devices for the purpose of imparting wear resistance.

As a method for forming a plating film with the above-mentioned plating solution, in a composite plating in which nickel-phosphorus alloy is used as a matrix and silicon carbide particles are dispersed, a superheat treatment temperature after plating is set to 470°C to 530°C. Has been proposed (for example, see Patent Document 1). The plating film formed by the plating method contains silicon carbide particles in the film, and therefore exhibits wear resistance when used in a sliding portion of a mechanical device.

JP-A-63-153228

The present invention is an electroless plating solution capable of forming a plating film having higher hardness, more excellent wear resistance, and more excellent slidability, and maintaining eutectoid properties and bath stability. An object of the present invention is to provide a plating film formed by a plating solution, a plated product having the plating film, and a method for forming the plating film.

The present inventors have conducted extensive studies to achieve the above object, and as a result, an electroless plating solution containing a water-soluble nickel compound, a reducing agent, a complexing agent, and silicon carbide as essential components An electroless plating solution containing a polymer surfactant and/or an aromatic sulfonic acid formalin condensate or a salt thereof, and having a phosphorus content of 0.1 to 4% by mass in the obtained plating film. It is found that the above object can be achieved by a plating film formed by the electroless plating solution, and a plating film forming method having a step of forming a plating film by contacting an object to be plated with the plating solution, The present invention has been completed.

That is, the present invention includes the following aspects.

Item 1. A water-soluble nickel compound, a reducing agent, a complexing agent, and an electroless plating solution containing silicon carbide as an essential component,
A polycarboxylic acid type polymer surfactant and/or an aromatic sulfonic acid formalin condensate or a salt thereof is contained, and the phosphorus content of the obtained plating film is 0.1 to 4% by mass. Electroless plating solution.

Item 2. Item 2. The electroless plating solution according to Item 1, wherein the aromatic sulfonic acid formalin condensate is a naphthalene sulfonic acid formalin condensate.

Item 3. Item 3. The electroless plating solution according to Item 1 or 2, wherein the silicon carbide has an average particle diameter of 0.1 to 3.0 µm.

Item 4. Item 4. The electroless plating solution according to any one of Items 1 to 3, wherein the content of the silicon carbide is 0.01 to 100 g/L.

Item 5. A plating film formed using the electroless plating solution according to any one of Items 1 to 4.

Item 6. A plated product having the plating film according to Item 5.

Item 7. Item 5. A method for forming a plating film, which comprises a step 1 of contacting an object to be plated with the electroless plating solution according to any one of Items 1 to 4 to form a plating film.

Item 8. Item 8. The method for forming a plating film according to Item 7, which includes Step 2 of heat-treating the electroless plating film formed in Step 1.

Item 9. Item 9. The method for forming a plating film according to Item 8, wherein the heat treatment temperature is 400° C. or lower.

According to the present invention, an electroless plating solution that has a higher hardness, is more excellent in wear resistance, and can form a plating film having better slidability, and that maintains eutectoid properties and bath stability, A plating film formed by an electroless plating solution, a plated product having the plating film, and a method for forming the plating film can be provided.

In this specification, the expressions "containing" and "including" include the concepts of "containing", "including", "consisting essentially of" and "consisting solely of".

1. Electroless plating solution The electroless plating solution of the present invention is
An electroless plating solution containing a water-soluble nickel compound, a reducing agent, a complexing agent, and silicon carbide as essential components, which comprises a polycarboxylic acid type polymer surfactant and/or an aromatic sulfonic acid formalin condensate or a product thereof. The salt content is included, and the phosphorus content of the obtained plating film is 0.1 to 4 mass %.

The water-soluble nickel compound can be used without particular limitation as long as it is soluble in the plating solution and an aqueous solution having a predetermined concentration can be obtained. For example, nickel sulfate, nickel chloride, nickel sulfamate, nickel hypophosphite and the like can be used. In particular, nickel sulfate is preferable because it has good solubility. The water-soluble nickel compounds may be used alone or in combination of two or more. From the viewpoint of bath stability and the like, the concentration of the water-soluble nickel compound is preferably about 0.001 to 1 mol/L, more preferably about 0.01 to 0.3 mol/L, and 0.01 It is more preferable to set the amount to about 0.03 mol/L.

The reducing agent is also not particularly limited, and known reducing agents used in electroless plating solutions can be used. Examples of such reducing agents include phosphorus-containing reducing agents such as hypophosphorous acid and hypophosphite salts (sodium salt, potassium salt, ammonium salt), dimethylamine borane, hydrazine and the like. Among these, from the viewpoint of bath stability and the like, a phosphorus-containing reducing agent is preferable, hypophosphorous acid and hypophosphite are more preferable, and hypophosphite is further preferable. The reducing agent may be used alone or in combination of two or more. The concentration of the reducing agent is preferably about 0.001 to 1 mol/L, and more preferably about 0.002 to 0.5 mol/L from the viewpoint of bath stability and the like.

The complexing agent is also not particularly limited, and a known complexing agent used in the electroless plating solution can be used. Such complexing agents include monocarboxylic acids such as acetic acid and formic acid, ammonium salts, potassium salts and sodium salts thereof; dicarboxylic acids such as malonic acid, succinic acid, adipic acid, maleic acid and fumaric acid, and the like. Ammonium salts, potassium salts, sodium salts, etc.; hydroxycarboxylic acids such as malic acid, lactic acid, glycolic acid, gluconic acid, citric acid, etc., ammonium salts, potassium salts, sodium salts thereof, etc.; ethylenediamine diacetic acid, 1-hydroxyethylidene Examples include -1,1-diphosphonic acid, ammonium salts, potassium salts and sodium salts thereof, aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, and sodium salts, potassium salts and ammonium salts thereof. Furthermore, phosphonic acids, amino acids such as glycine, glutamic acid, etc. can also be used as complexing agents. Among these, amino acids such as glycine and hydroxycarboxylic acids such as lactic acid are preferable from the viewpoint of bath stability and the like. These complexing agents can be used alone or in combination of two or more. From the viewpoint of bath stability and the like, the compounding amount of the complexing agent is preferably about 0.001 to 2 mol/L, more preferably about 0.002 to 1 mol/L.

The electroless plating solution of the present invention contains silicon carbide particles. The shape of the silicon carbide particles is not particularly limited, and may be any shape such as spherical shape, pyramid shape, and cubic shape.

The average particle diameter of the silicon carbide particles is preferably 0.1 to 5.0 μm, more preferably 0.1 to 3.0 μm, from the viewpoint of wear resistance, slidability and the like. If the average particle size of the silicon carbide particles is too large, other members in contact with the plating film to be formed may be easily worn, and if it is too small, the wear resistance of the plating film to be formed may be reduced. ..

From the viewpoint of wear resistance, slidability, etc., the content of silicon carbide particles is preferably 0.05 to 200 g/L, more preferably 0.1 to 100 g/L, and further preferably 0.5 to 100 g/L. preferable. If the content of silicon carbide particles is too large, other members in contact with the formed plating film may be easily worn, and if it is too small, the wear resistance of the formed plating film may be reduced.

The electroless plating solution of the present invention includes a polycarboxylic acid type polymer surfactant and/or an aromatic sulfonic acid formalin condensate or a salt thereof (in the present specification, these may be collectively referred to as “A component”). .) is included. As a result, the dispersibility of SiC, good eutectoid properties, bath stability and the like can be maintained even in a low phosphorus bath.

The naphthalene ring is typically mentioned as the aromatic moiety in the aromatic sulfonic acid formalin condensate. However, the present invention is not limited to this, and other aromatic rings such as benzene ring, anthracene ring, tetracene ring, pentacene ring, phenanthrene ring and the like having 6 to 20 carbon atoms (preferably 6 to 12, more preferably 6 to 10). ) Is also included.

The aromatic sulfonic acid formalin condensate is not particularly limited, but typically includes naphthalene sulfonic acid formalin condensate.

The type of salt is not particularly limited. Examples of the salt include sodium salt.

The content of the component A is preferably 0.001 to 30 g/L, more preferably 0.005 to 20 g/L, and 0.01 from the viewpoint of dispersibility of SiC, good eutectoid properties, bath stability and the like. More preferably, it is 10 g/L.

The phosphorus content rate (=content rate as a phosphorus element) of the plating film obtained by the electroless plating solution of the present invention is 0.1 to 4 mass% (in other words, the electroless plating solution of the present invention is For forming a plating film having a phosphorus content of 0.1 to 4 mass %.). The content is preferably 1 to 3 mass% from the viewpoint of wear resistance, slidability and the like. The plating film having such a phosphorus content can be obtained by adjusting the content of the phosphorus-containing component that can be deposited as the plating film in the plating solution. For example, when the phosphorus-containing component contains a phosphorus-containing reducing agent, the content of the phosphorus-containing reducing agent in the electroless plating solution of the present invention is preferably about 0.001 to 0.20 mol/L. Is more preferably about 0.002 to 0.18 mol/L, and even more preferably about 0.01 to 0.16 mol/L.

The electroless plating solution of the present invention may further contain various additives that are commonly used, if necessary. For example, as the stabilizer, a lead salt such as lead nitrate or lead acetate; a bismuth salt such as bismuth nitrate or bismuth acetate; a sulfur compound such as sodium thiosulfate may be added alone or in combination of two or more. .. The amount of the stabilizer added is not particularly limited, but may be, for example, about 0.01 to 100 mg/L.

Further, acetic acid, boric acid, phosphoric acid, phosphorous acid, carbonic acid, their sodium salts, potassium salts, ammonium salts and the like can be blended as the pH buffering agent. Among these, acetic acid is preferable from the viewpoint of bath stability and the like. The amount of the buffer compounded is not particularly limited, but is preferably about 0.002 to 1 mol/L from the viewpoint of bath stability and the like.

The pH of the electroless plating solution of the present invention may be generally about 2-12, preferably about 4-10, and more preferably about 5-8. For pH adjustment, inorganic acids such as sulfuric acid and phosphoric acid, sodium hydroxide, aqueous ammonia and the like can be used.

2. Plating film The present invention is also a plating film formed using the above electroless plating solution. The thickness of the plating film is preferably about 0.1 to 1000 μm, more preferably about 0.5 to 100 μm, still more preferably about 1 to 50 μm.

The phosphorus content rate (=content rate as a phosphorus element) of the plating film is 0.1 to 4% by mass. The content rate is preferably 1 to 3% by mass from the viewpoint of wear resistance, slidability and the like. Is.

The Vickers hardness of the plating film is, for example, about 500 (preferably 600, more preferably 700) to 800 when heat treatment is not performed in the plating film forming method described later. The hardness is, for example, about 780 (preferably 800, more preferably 820, further preferably 850) to 1300 when heat treatment is performed by the method for forming a plating film described later. In particular, a heat treatment at 300° C. to 350° C. gives a hardness of about 1000 to 1300.

In this specification, the Vickers hardness of the plating film is a value measured with a load of 100 gf (0.98 N) using a Vickers hardness meter (HM-200 manufactured by Mitutoyo).

The wear resistance of the plating film is, for example, 4 mg or less, preferably 3.5 mg or less, and more preferably 3 mg or less, as measured by the following wear resistance test. The lower limit is not particularly limited and is, for example, 0.5 mg, 1 mg, 2 mg, 2.5 mg.

In the present specification, the above-mentioned wear amount is a load of 1.5 kgf (14.7 N), a polishing paper: # on the surface of the plating film by using a Suga wear tester (NUS-ISO-3 manufactured by Suga Tester Co., Ltd.). It is a value measured by performing a test under the measurement conditions of 600 and the number of reciprocations: 300 times.

As for the slidability of the plating film, the average value of the friction coefficient measured by the following friction and wear tester is, for example, less than 0.7. In the case of no heat treatment, the value is preferably 0.65 or less, more preferably 0.6 or less. The lower limit of the value is not particularly limited and is, for example, 0.2, 0.3, 0.4, 0.5.

In the present specification, the average value of the above-mentioned friction coefficient is measured by a weighted reciprocating reciprocal measurement using a load fluctuation type friction and wear test system (Product name: Tribogear HHS-2000 manufactured by Shinto Kagaku Co., Ltd.) on the surface of the plating film. According to the measuring method, the measuring element φ10 mm SUS ball, 100 to 500 gf, the number of reciprocations 50 times, the moving distance 15 mm, the moving speed 5 mm/sec, the sample rate of 50 Hz, the friction coefficient was measured, and each load of 100 to 500 gf was measured. It is a value obtained by calculating the average value of the friction coefficient at the 50th round trip.

3. The present invention also provides an electroless plating solution containing a water-soluble nickel compound, a reducing agent, a complexing agent, and silicon carbide as essential components, which comprises a polycarboxylic acid type polymer surfactant and / Or an electroless plating solution containing an aromatic sulfonic acid formalin condensate or a salt thereof, and the obtained plating film has a phosphorus content of 0.1 to 4% by mass. It is also a method of forming a plating film, which has a step 1 of forming a plating film by bringing them into contact with each other.

(Process 1)
Step 1 is a step of forming a plating film by bringing an object to be plated into contact with the electroless plating solution. The above-mentioned electroless plating solution can be used. In order to form a plating film using the above electroless plating solution, the electroless plating solution may be brought into contact with the object to be plated according to a conventional method. Usually, a plating film can be efficiently formed by immersing the object to be plated in the electroless plating solution.

The liquid temperature of the electroless plating solution may be usually about 25° C. or higher, preferably about 40 to 100° C. If necessary, the plating solution can be stirred or the object to be plated can be shaken.

The material to be plated is not particularly limited. For example, since metals such as aluminum, iron, cobalt, nickel, and palladium, and alloys thereof have catalytic properties for reduction deposition of electroless plating, a direct plating film is formed after pretreatment according to a conventional method. can do. For non-catalytic metals such as copper, glass, ceramics and the like, plating treatment may be performed after depositing metal catalyst nuclei such as palladium nuclei according to a conventional method.

(Process 2)
The method for forming a plating film of the present invention may further include a step 2 of heat-treating the electroless plating film formed in the step 1.

The method for heat-treating the electroless plating film formed in step 1 is not particularly limited, and heat treatment can be performed by a conventionally known method. Examples of the method of heat-treating the electroless plating film include a method of heating the plating film formed on the object to be plated together with the object to be plated in a heating furnace.

Although the temperature of the heat treatment is not particularly limited, it is preferably 400° C. or lower. In another aspect of the present invention, 100 to 300°C is more preferable, 130 to 200°C is further preferable, 150 to 190°C is further preferable, and 160 to 180°C is particularly preferable. In one aspect of the present invention, from the viewpoint of obtaining higher hardness, 300 to 400°C is more preferable. The above lower limit value is preferable from the viewpoint of further improving the hardness and the wear amount. The above upper limit value is preferable from the viewpoint of further increasing the strength of the plating film and the amount of wear.

The heating time of the heat treatment is not particularly limited, but is preferably 10 to 180 minutes, more preferably 30 to 120 minutes. If the heating time is too short, the wear resistance of the plating film may not be sufficient, and if it is too long, the friction coefficient of the plating film surface may be high, and the wear of other members in contact with the plating film may not be sufficiently suppressed. ..

4. Plated Product The present invention also provides a plated product having the above plating film. The plated product is not particularly limited as long as it has the plating film of the present invention, and the plating film may be formed on the surface of the object to be plated.

The material of the object to be plated is not particularly limited, but examples thereof include metals such as aluminum, iron, cobalt, nickel, palladium, and copper, alloys thereof, glass, ceramics, and the like.

When the plated product of the present invention is a member that slides with another member such as a sliding portion of a mechanical device or a sliding part of an automobile, the wear of the other member that slides with the plated product of the present invention Can be suppressed.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

(Preparation of electroless plating solution)
The electroless plating solutions of Examples 1-20 and Comparative Examples 1-5 were prepared according to the formulations shown in Tables 1-5. As the silicon carbide, silicon carbide particles (average particle diameter 0.5 μm) were used. Water was used as the solvent.

Using the obtained electroless plating solutions of Examples and Comparative Examples, a plating film was formed by the following method.

Using each electroless nickel plating solution containing the compounds shown in Tables 1 to 5, a mild steel plate (JIS-SPCC-SB) 5 x 10 cm was plated in an electroless nickel plating solution at a bath temperature of 90°C. By dipping the object to be plated, an electroless nickel plating film having a thickness of 30 μm was formed.

The pretreatment process and the chemicals used are as follows.
(1) Immersion degreasing (trade name: A-screen 801 Okuno Pharmaceutical Co., Ltd.)
(2) Electrolytic degreasing (trade name: Top Cleaner E, Okuno Pharmaceutical Co., Ltd.)
(3) Acid activity (Trade name: Top Sun Okuno Pharmaceutical Co., Ltd.)
Each of the obtained samples was heat treated at 170° C. for 60 minutes in a heating furnace, and then the phosphorus content, hardness, abrasion resistance and slidability were measured by the following methods.

(Phosphorus content rate)
The phosphorus content of the plating film was measured by an energy dispersive X-ray analyzer (HORIBA, Ltd., EMAX ENERGY EX-350).

(hardness)
The Vickers hardness of the plating film was measured with a load of 100 gf (0.98N) using a Vickers hardness meter (HM-200 manufactured by Mitutoyo).

(Abrasion resistance)
For the surface of the plating film, using a Suga abrasion tester (manufactured by Suga Test Instruments, NUS-ISO-3), load: 1.5 kgf (14.7 N), abrasive paper: #600, and number of reciprocations: 300 times A test was performed under the conditions and the amount of wear was measured.

(Sliding property)
With respect to the surface of the plating film, using a load fluctuation type friction wear test system (Shinto Kagaku Co., Ltd. product name: Tribogear HHS-2000), a measuring element φ10 mm SUS ball, 100-500 gf The coefficient of friction was measured under the conditions of 50 reciprocations, a moving distance of 15 mm, a moving speed of 5 mm/sec, and a sample rate of 50 Hz. The average value of the friction coefficient at the 50th reciprocation for each load of 100 to 500 gf was calculated and used as the measured value of the friction coefficient.

(Eutectoid)
The surface and cross section of the plating film were observed with a scanning electron microscope (S-3400N, manufactured by Hitachi), and the eutectoid state of silicon carbide in the film was evaluated.
<Evaluation criteria>
○ Eutectoid uniformly △ Slightly aggregated × Severely aggregated.

(Bath stability)
After the plating treatment, the plating solution was allowed to warm at 90° C., and the state of the plating solution and the amount of Ni deposited in the beaker were visually evaluated.
<Evaluation criteria>
○Good bath stability △Slightly unstable, a little Ni was deposited on the bottom of the beaker ×Bath decomposition occurred, and Ni was entirely deposited on the beaker bottom.

The results are shown in Tables 1-5.

As is clear from Tables 1 to 5, it was found that a plating solution having a low phosphorus content and containing silicon carbide can form a plating film having high hardness, excellent wear resistance, and excellent slidability. .. In a low phosphorus bath, it was difficult to maintain dispersibility of SiC, good eutectoid properties, bath stability, etc., but a polycarboxylic acid type polymer surfactant and/or formalin aromatic sulfonate was used. These problems could be solved by adding a condensate or a salt thereof.

Claims (9)

A water-soluble nickel compound, a reducing agent, a complexing agent, and an electroless plating solution containing silicon carbide as an essential component,
A polycarboxylic acid type polymer surfactant and/or an aromatic sulfonic acid formalin condensate or a salt thereof is contained, and the phosphorus content of the obtained plating film is 0.1 to 4% by mass. Electroless plating solution. The electroless plating solution according to claim 1, wherein the aromatic sulfonic acid formalin condensate is a naphthalene sulfonic acid formalin condensate. The electroless plating solution according to claim 1 or 2, wherein the silicon carbide has an average particle diameter of 0.1 to 3.0 µm. The electroless plating solution according to claim 1, wherein the content of the silicon carbide is 0.01 to 100 g/L. A plating film formed using the electroless plating solution according to claim 1. A plated product having the plating film according to claim 5. A method for forming a plating film, comprising the step 1 of forming a plating film by bringing an object to be plated into contact with the electroless plating solution according to any one of claims 1 to 4. The method for forming a plating film according to claim 7, further comprising the step 2 of heat-treating the electroless plating film formed in step 1. The method for forming a plating film according to claim 8, wherein the temperature of the heat treatment is 400° C. or lower.