WO2019087474A1

WO2019087474A1 - Electroless nickel-phosphorus-cobalt plating bath, and electroless nickel-phosphorus-cobalt plating film

Info

Publication number: WO2019087474A1
Application number: PCT/JP2018/026954
Authority: WO
Inventors: 雅亮佐藤; 成吾黒坂
Original assignee: 上村工業株式会社
Priority date: 2017-11-06
Filing date: 2018-07-18
Publication date: 2019-05-09
Also published as: CN111295466A; DE112018005312T5; JP6934396B2; JP2019085607A

Abstract

An electroless nickel-phosphorus-cobalt plating bath contains a water-soluble nickel salt, a hypophosphorous acid salt, a cobalt-containing compound and a heavy metal compound, and additionally contains at least one component selected from the group consisting of an acetylene compound, an iodide ion source or an iodic acid ion source, and a nitro-group-containing aromatic compound that contains at least one nitro group. The concentration of the acetylene compound is 10 to 120 mg/L, the concentration of the iodide ion source or the iodic acid ion source is 10 to 4000 mg/L, and the concentration of the nitro-group-containing aromatic compound is 0.1 to 5000 mg/L.

Description

Electroless nickel-phosphorus-cobalt plating bath and electroless nickel-phosphorus-cobalt plating film

The present invention relates to an electroless nickel-phosphorus-cobalt plating bath and an electroless nickel-phosphorus-cobalt plating film.

Conventionally, in the field of electronic components, electroless nickel plating films are formed on Al and Cu patterns of flexible substrates and silicon wafer substrates.

Unlike the electroplating method, the electroless nickel plating method is a method capable of forming a metallic nickel film on the surface of a material to be plated simply by immersing the material to be plated in a plating bath, and the shape and type of the material. Regardless of the film thickness, a film of uniform thickness can be obtained, so it is suitable for plating of complex shapes and precision parts.

Here, in recent years, a plating film excellent in wear resistance is required, but in the conventional electroless nickel-phosphorus plating film, although the hardness is sufficient (Vickers hardness is 650 or more), the wear resistance is There was a problem of being inadequate.

Then, in order to solve the said problem, the electroless nickel plating film containing cobalt is proposed. More specifically, disclosed is an electroless nickel plating film containing 1 to 50% by mass of cobalt, 1 to 20% by mass of tungsten, and 1 to 4% by mass of phosphorus. And while such an electroless nickel plating film has high hardness in the wide temperature range ranging from room temperature to a high temperature range, it is described as it is excellent in abrasion resistance (for example, refer to patent documents 1).

Patent No. 4185523

However, the plating bath used when forming the above conventional electroless nickel-phosphorus-cobalt plating film (the one containing cobalt in the electroless nickel-phosphorus plating bath) is likely to cause abnormal plating of cobalt. Therefore, it was unstable as a bath. Further, as a countermeasure for this, when the concentration of lead or bismuth used as a stabilizer is increased, there is a problem that the occurrence of defects around the plating and the film thickness become thin, so that the galling occurs.

Therefore, in view of the above problems, the present invention is capable of forming a plated film having high hardness and excellent in wear resistance and appearance without causing instability of the plating bath. -To provide a cobalt plating bath.

In order to achieve the above object, the electroless nickel-phosphorus-cobalt plating bath according to the present invention comprises an electroless nickel containing a water-soluble nickel salt, a hypophosphite, a cobalt-containing compound and a heavy metal compound. -A phosphorus-cobalt plating bath, which further contains at least one selected from the group consisting of an acetylene compound, an iodide ion source or an iodate ion source, and a nitro group-containing aromatic compound containing one or more nitro groups Concentration of the acetylene compound is 10 to 120 mg / L, concentration of the iodide ion source or iodate ion source is 10 to 4000 mg / L, and concentration of the nitro group-containing aromatic compound is 0.1 to 5000 mg / L It is characterized by being.

According to the present invention, an electroless nickel having high hardness and capable of forming a plating film excellent in wear resistance and appearance without causing destabilization of a plating bath caused by abnormal plating of cobalt. It becomes possible to provide a phosphorus-cobalt plating bath.

Hereinafter, the electroless nickel-phosphorus-cobalt plating bath and the electroless nickel-phosphorus-cobalt coating in the present embodiment will be described.

<Electroless nickel-phosphorus-cobalt plating bath>
The electroless nickel-phosphorus-cobalt plating film of the present embodiment comprises an acetylene compound and an iodide ion source in a plating bath containing a water-soluble nickel salt, a hypophosphite, a cobalt-containing compound, and a heavy metal compound. Or electroless nickel-phosphorus-cobalt plating bath (hereinafter simply referred to as "plating bath") containing at least one member selected from the group consisting of an iodate ion source and a nitro group-containing aromatic compound containing one or more nitro groups In some cases, the plating process can be performed on the object to be plated.

(Water soluble nickel salt)
The water-soluble nickel salt is not particularly limited as long as it is soluble in the plating bath and an aqueous solution having a predetermined concentration can be obtained. For example, inorganic water-soluble nickel salts such as nickel sulfate, nickel chloride and nickel hypophosphite, and organic water-soluble nickel salts such as nickel acetate and nickel malate can be used. In addition, these water-soluble nickel salts can be used individually or in mixture of 2 or more types.

The concentration of nickel ions in the plating bath is, for example, preferably 3 to 7 g / L, more preferably 4 to 6 g / L as metallic nickel. If the nickel concentration is too low, the plating rate may be slow, which is not preferable. In addition, if the nickel concentration is too high, white turbidity may occur in the plating bath or the viscosity of the plating bath may increase, so the uniform deposition property may decrease and pits may occur in the formed plated film. Not desirable.

(Hypophosphite)
Examples of hypophosphite as a reducing agent include sodium hypophosphite (sodium hypophosphite) and potassium hypophosphite.

In addition, the concentration of hypophosphite in the plating bath is, for example, preferably 5 to 50 g / L, more preferably 10 to 40 g / L. If the concentration of the reducing agent is too low, the plating rate may be slow, which is not preferable. In addition, when the concentration of the reducing agent is too high, the phosphorus content in the film may be an amorphous structure due to the fact that it is more than 4% by mass described later, and the bath stability is also reduced. Therefore, the plating bath may be decomposed, which is not preferable.

In addition, by using hypophosphite as the reducing agent, at least 0.1% by mass or more of phosphorus is co-deposited.

(Cobalt-containing compound)
As a cobalt containing compound, cobalt sulfate (II) heptahydrate etc. are mentioned, for example. The concentration of cobalt ions in the plating bath is preferably 0.3 to 10 g / L, more preferably 0.6 to 5 g / L. If the concentration of cobalt ions is too low, the wear resistance of the electroless nickel-phosphorus plating film may not be sufficiently improved, which is not preferable. If the concentration of cobalt ions is too high, the plating bath may become unstable and the plating bath may decompose, which is not preferable.

(Heavy metal compounds)
The heavy metal compound acts as a stabilizer and is used to stabilize the plating bath together with an acetylene compound, an iodide ion source or an iodate ion source, and a nitro group-containing aromatic compound described later.

Examples of this heavy metal compound include lead compounds such as lead acetate, bismuth compounds such as bismuth acetate, thallium compounds such as thallium carbonate, and cadmium compounds such as cadmium acetate. These stabilizers may be used alone or in combination of two or more.

The concentration of heavy metal ions (eg, Pb ions) in the plating bath varies depending on the type of heavy metal compound used, but is preferably 0.1 to 10 mg / L, more preferably 0.3 to 5 mg / L. is there. When the concentration of heavy metal ions is too low, the bath stability is unfavorably reduced. In addition, when the concentration of heavy metal ions is too high, the appearance unevenness easily occurs, which is not preferable.

(Acetylene compound)
As an acetylene compound, it is generated from a reducing agent generated in a plating bath to hide the active substance that causes the instability of the plating bath, and from the viewpoint of enhancing the bath stability, -C-C- in the molecule. Substantially water soluble acetylenic compounds having a structure are preferred. As such an acetylene compound, for example, water molecule such as hydroxyl group, hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, methoxy group, ethoxy group, carboxyl group, hydroxyethoxy group, sulfo group, amino group in the molecule What has a sex functional group is mentioned.

In addition, as a preferable acetylene compound, more specifically, the following general formula (I)
R ¹ -C≡C-R ² (I)
(Wherein, R ¹ and / or R ² is a substituent having the above-mentioned water-soluble functional group. R ¹ and R ² may be the same or different)
The acetylene compound shown by these is illustrated.

Here, as the substituent R ¹ or R ² , for example, hydrogen, a halogen group, a diethylaminoethyl group, a morpholinomethyl group, an alkyl group, an alkenyl group, an alkynyl group, a cyano group, and the above-mentioned water-soluble compounds The substituent which introduce | transduced the sex functional group is mentioned.

Moreover, as the above-mentioned acetylene compound, for example, butyne diol, butyne diol ethoxylate, propargyl alcohol, propargyl alcohol ethoxylate, propargyl alcohol propoxylate, propargyl alcohol butylate, dimethylaminopropyne, aminopropyne and the like can be mentioned. . Among these, propargyl alcohol and / or a derivative thereof is preferable from the viewpoint of the adsorptivity to fine particles such as nickel. In addition, it is preferable that the propargyl alcohol be ethoxylated and / or propoxylated from the viewpoint of stable operation without vaporization even when plating at a high temperature of about 90 ° C. Such ethoxylated and / or propoxylated propargyl alcohol includes propargyl alcohol ethoxylate and propargyl alcohol propoxylate.

The concentration of the acetylene compound in the plating bath of the present invention is 10 to 120 mg / L, preferably 40 to 80 mg / L. If the concentration of the acetylene compound is less than 10 mg / L, the bath stability may be deteriorated or the flexibility of the film may be deteriorated. On the other hand, if it exceeds 120 mg / L, the plating reaction is stopped and the appearance unevenness is easily generated, which is not preferable.

(Iodo ion source or iodate ion source)
The iodide ion source or iodate ion source, iodide ion in the plating bath (I ^-) or iodate (IO 3 _^-) is particularly so long as it acts gently against reducing agents as an oxidizing agent It is not limited. As an iodide ion source, potassium iodide, iron iodide, nickel iodide, lithium iodide, sodium iodide etc. can be used, for example. Moreover, as an iodate ion source, potassium iodate, sodium iodate, ammonium iodate etc. can be used, for example. Moreover, these iodide ion sources or iodate ion sources may be used alone or in combination of two or more.

The addition effect of iodide ion or iodate ion is equal, and as described above, since both ions gently act on the reducing agent as the oxidizing agent, the appropriate concentration range is wide. In the plating bath of the present invention, the concentration of the iodide ion source or the iodate ion source is 10 to 4000 mg / L, and in this concentration range, the iodide ion source and the iodate ion source behave exactly the same. And by making an iodide ion source or an iodate ion source into such a concentration, a plating bath can be stabilized and a fall of the deposition rate of a nickel plating film can be prevented. In particular, in the plating bath according to the present embodiment, the concentration of the iodide ion source or the iodate ion source is preferably 500 to 2000 mg / L, whereby the state of the plating bath can be made more stable. And the reduction of the deposition rate of the nickel plating film can be prevented more effectively.

(Nitro group-containing aromatic compound)
The nitro group-containing aromatic compound may contain one or more nitro groups. That is, one or more nitro groups may be contained in the aromatic compound. The nitro group-containing aromatic compound preferably contains 1 to 3 nitro groups, preferably 1 to 2 nitro groups, and more preferably 1 nitro group from the viewpoint of handling. .

The nitro group-containing aromatic compound is at least selected from the group consisting of benzene having a nitro group and benzene having a substituent other than a nitro group, naphthalene having a substituent other than a nitro group, and alkali metal salts thereof. It is one kind. The substituent is preferably at least one selected from the group consisting of a carboxyl group, a hydroxyl group, a halogen atom, a sulfonic acid group, an ester group, an alkoxy group, and an amino group.

The substituent is more preferably at least one selected from the group consisting of a carboxyl group, a hydroxyl group, a halogen atom, a sulfonic acid group, and an amino group.

When the nitro group-containing aromatic compound is an alkali metal salt, the nitro group-containing aromatic compound is preferably at least one of a sodium salt and a potassium salt.

The halogen group is preferably at least one selected from the group consisting of a chloro group, a bromo group, and an iodo group.

Specific examples of the nitro group-containing aromatic compound include nitrobenzene, 2,4,6-trinitrotoluene, 2-nitrophenol, 4-nitrophenol, 2-nitroaniline, 4-nitroaniline, 3-nitrobenzoic acid, 4 -Nitrobenzoic acid, 4-nitrophthalimide, 2,4,6-trinitrophenol, 4-amino-2-nitrophenol, 2-amino-4-nitrophenol, 5-nitroisophthalic acid, 4-bromonitrobenzene, 2 -Bromo-6-chloro-4-nitroaniline, sodium 3-nitrobenzenesulfonate, sodium 2-nitroaniline-4-sulfonate, 2,4-dinitrobenzenesulfonic acid, 4-chloro-3-nitrobenzoic acid, and 3-methyl-4-nitroaniline and the like.

The concentration of the nitro group-containing aromatic compound in the plating bath varies depending on the type of heavy metal compound used, but is 0.1 to 5000 mg / L, preferably 1.0 to 1000 mg / L. When the concentration of the nitro group-containing aromatic compound is too low, the bath stability is unfavorably reduced. In addition, when the concentration of the nitro group-containing aromatic compound is too high, the appearance unevenness easily occurs, which is not preferable.

As described above, in the plating bath of the present invention, in addition to the heavy metal compound acting as a conventional stabilizer, an acetylene compound, an iodide ion source or an iodate ion source, and a nitro group-containing one or more nitro group. It contains at least one selected from the group consisting of aromatic compounds.

Among these, as for acetylene compounds, the active substance which is generated from the reducing agent and causes destabilization of the plating bath is concealed, and as for the iodide ion source or the iodate ion source and the nitro group-containing aromatic compound, Since it acts as an oxidizing agent on the agent and suppresses excessive oxidation reaction, abnormal plating of cobalt can be suppressed in each case.

Therefore, it is possible to stabilize the plating bath without causing the occurrence of defects in the area around the plating, the film thickness becoming thin, and the occurrence of galling etc. when the concentration of the conventional heavy metal stabilizer component is increased. become. As a result, an electroless nickel-phosphorus-cobalt plating film can be formed without causing destabilization of the plating bath due to abnormal plating of cobalt.

When the plating bath is to be stabilized using only the acetylene compound acting as an oxidant without using the above-mentioned heavy metal compound acting as a stabilizer component, a large amount of the oxidant is required, and no plating ( In the plating bath of the present invention, it is necessary to use a heavy metal compound and an oxidizing agent in combination, because the plating may not be deposited).

(Complexing agent)
As the complexing agent, various complexing agents used in known electroless nickel plating baths can be used. Specific examples of the complexing agent include amino acids such as glycine, alanine, arginine, aspartic acid, glutamic acid, lysine and phenylalanine, monocarboxylic acids such as lactic acid, propionic acid, glycolic acid and gluconic acid, tartaric acid, oxalic acid and succinic acid And dicarboxylic acids such as malic acid, and tricarboxylic acids such as citric acid. Moreover, these salts, for example, sodium salt, potassium salt etc. can also be used as a complexing agent. In addition, these complexing agents can be used individually or in mixture of 2 or more types.

The concentration of the complexing agent in the plating bath varies depending on the type of complexing agent used, but is preferably 10 to 200 g / L, more preferably 30 to 100 g / L. If the concentration of the complexing agent is too low, precipitation of nickel hydroxide is likely to occur, which is not preferable. In addition, when the concentration of the complexing agent is too high, the viscosity of the plating bath becomes high, so the uniform deposition may be reduced, which is not preferable.

(PH)
The pH of the plating bath according to the present embodiment is preferably 5.5 to 7.5, and more preferably 6.0 to 7 in order to stabilize the plating bath and to suppress the appearance unevenness. 0 is more preferable. The pH can be adjusted with an alkali such as aqueous ammonia or sodium hydroxide (caustic soda), or an acid such as sulfuric acid, hydrochloric acid or nitric acid.

(Temperature of plating bath)
Further, the temperature of the plating bath to be used is preferably 75 to 95 ° C., and particularly preferably 80 to 90 ° C. If the temperature of the plating bath is too high, the plating bath itself may be thermally decomposed, and if the temperature of the plating bath is too low, the plating reaction may be reduced, which is not preferable. The plating treatment time can be appropriately changed depending on the thickness of the plating film to be formed, but it is generally 30 to 240 minutes.

(Others)
The plating bath of the present invention can further contain various known additives to be blended in the electroless nickel plating bath, as necessary. Examples of the additive include reaction accelerators, brighteners, surfactants, functionalizing agents and the like. These types are not particularly limited, and commonly used ones can be adopted.

<Electroless nickel-phosphorus-cobalt plating film>
The electroless nickel-phosphorus-cobalt plated film (hereinafter sometimes simply referred to as “plated film”) of the present embodiment is a plated film formed on an object to be plated. Although it does not specifically limit as a to-be-plated thing in which the plating film of this embodiment is formed, For example, metals, such as iron, aluminum, copper, or the alloy of metals is mentioned.

In the plating film of the present invention, the content of phosphorus is 0.1 to 4% by mass, and 1 to 2% by mass is particularly preferable. By setting the content of phosphorus to 0.1 to 4% by mass, a microcrystalline structure is obtained, so that the hardness of the plated film is improved.

In addition, in the plating film of the present invention, cobalt is contained, and by blending cobalt in the film, a part of nickel in the crystal is replaced with cobalt, thereby improving the toughness of the film, and as a result, Wear resistance is improved.

In the plated film of the present invention, the content of cobalt is 1 to 20% by mass, and 2 to 9% by mass is particularly preferable. By setting the content of cobalt to 1 to 20% by mass, the toughness of the plating film is improved, and the wear resistance of the plating film is improved.

And since the plating film of this embodiment formed by the plating process using the above-mentioned plating bath has high hardness (Vickers hardness is 650 or more), it becomes possible to implement | achieve the outstanding abrasion resistance. Moreover, since the appearance unevenness of a plating film does not arise, it becomes possible to implement | achieve the outstanding appearance.

The thickness of the plating film is preferably 10 to 40 μm, and particularly preferably 20 to 30 μm. This is because when the plating film is too thin, the original function of the plating may not be exhibited, such as a decrease in corrosion resistance, and when the plating film is too thick, uneven plating appearance and the like are easily generated.

Hereinafter, the invention according to the present application will be more specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1 to 21, Comparative Examples 1 to 9)
(Preparation of plating bath)
Nickel (II) sulfate hexahydrate which is a water-soluble nickel salt, sodium hypophosphite as a reducing agent, lead acetate (II) trihydrate which is a heavy metal compound, and cobalt sulfate which is a cobalt-containing compound (II) heptahydrate, propargyl alcohol ethoxylate acting as an oxidizing agent, potassium iodate or nitrobenzene, glycine which is a complexing agent, and sodium hydroxide which is a pH adjusting agent; The plating baths of Examples 1 to 21 and Comparative Examples 1 to 9 were prepared by mixing and stirring so as to obtain the concentration shown in the following. The temperature of the plating bath was set to 90 ° C., and the pH was set to 6.8.

(Plating treatment)
Next, the prepared SPCC-SB plate (size: 50 mm × 50 mm, thickness: 4 mm) is immersed in the prepared plating bath for 120 minutes, and electroless nickel having a thickness of 25 μm on the material to be plated A phosphorus-cobalt plating film was formed.

(Composition analysis of plating film)
Next, the composition of the formed plating film was analyzed. More specifically, the electroless nickel-phosphorus-cobalt plating film deposited is dissolved in nitric acid, and this solution is subjected to quantitative analysis of phosphorus and cobalt by ICP (manufactured by HORIBA, trade name: Ultima Expert) to dissolve it. From the weight of the plated film, the mass% of each component in the film was calculated. The above results are shown in Tables 3 to 4.

(Hardness of plating film)
Next, the hardness of the plating film formed by the above-mentioned plating treatment was measured by the method according to JIS Z 2244. Specifically, using a microhardness tester (manufactured by Mitutoyo, trade name: HM-125), the sample was pressed with a diamond indenter under a load of 100 gf and an indentation time of 15 seconds, and the indenter was removed The Vickers hardness was measured by dividing the test force by the contact area between the indenter and the sample calculated from the diagonal length of the indentation at the time (Vickers hardness HV = 0.1891 × F / d ² , F: test force [N ], D = diagonal length [mm]). The above results are shown in Tables 3 to 4.

(Abrasion resistance)
Next, a ball-on-disk test is performed using a wide area load friction and wear tester (trade name: Tribogear TYPE 35, manufactured by Kadoto Scientific Co., Ltd.) to obtain the abrasion resistance of the plated film formed by the above-described plating process. evaluated. More specifically, using alumina balls of 10 mm in diameter and lubricating oil, predetermined friction conditions (load: 15 kg, alumina balls of 1 cm in diameter are rotated at 250 rpm for 10 minutes, and the total friction distance is 78. Under the condition that 5 m of rotational wear is performed, the surface of the plating film is abraded under the condition that 5 m of rotational abrasion is performed, and the abrasion depth (difference in depth from the non-abraded part) is 4 points for each abrasion mark It measured and calculated the average value. The above results are shown in Tables 3 to 4.

(Plating appearance)
Next, the appearance of the plating film formed by the above-described plating treatment was visually evaluated according to the following criteria. The above results are shown in Tables 3 to 4.
:: The entire surface of the plating film is uniformly glossy ○: There is no unevenness in the plating film, and the entire surface of the plating film is uniform Δ: Non-uniform appearance occurs in part of the non-plated film

(Stability of plating bath)
In addition, the above-mentioned plating bath is left for 7 days in total for 7 days a day (ie, a 35 mm diameter stirrer piece is rotated at 300 rpm using a 1 L beaker and a 500 W heater, and raised at 90 ° C.) The condition of the plating bath when it was allowed to stand was visually observed and evaluated according to the following criteria.
◎: Nickel does not precipitate in the heater portion (the highest temperature portion), and fine powder of nickel does not occur in the entire plating bath ○: Nickel does not precipitate in the heater portion, but nickel in the entire plating bath微: Nickel is deposited on the heater part. ×: Nickel fine powder is generated throughout the plating bath and the plating bath is decomposed.

As shown in Tables 3 and 4, Examples 1 to 4, 13, 16 to 17 in which the concentration of the acetylene compound is 10 to 120 mg / L, and Examples in which the concentration of the iodate ion source is 10 to 4000 mg / L 5 to 8, 14, 18, Examples 20 to 21 in which the concentration of the iodide ion source is 10 to 4000 mg / L, and Example 9 in which the concentration of the nitro group-containing aromatic compound is 0.1 to 5000 mg / L It can be seen that, in Nos. 12, 15, and 19, it is possible to form a plated film having high hardness and excellent in wear resistance and appearance without causing instability of the plating bath.

The electroless nickel-phosphorus-cobalt plating bath of the present embodiment is suitably used for the formation of a plating film excellent in wear resistance and appearance.

Claims

An electroless nickel-phosphorus-cobalt plating bath comprising a water-soluble nickel salt, a hypophosphite, a cobalt-containing compound, and a heavy metal compound,
And at least one selected from the group consisting of an acetylene compound, an iodide ion source or an iodate ion source, and a nitro group-containing aromatic compound containing one or more nitro groups,
The concentration of the acetylene compound is 10 to 120 mg / L, the concentration of the iodide ion source or the iodate ion source is 10 to 4000 mg / L, and the concentration of the nitro group-containing aromatic compound is 0.1 to 5000 mg Electroless nickel-phosphorus-cobalt plating bath characterized in that
The electroless nickel-phosphorus-cobalt plating bath according to claim 1, wherein the acetylene compound is propargyl alcohol and / or a derivative thereof.
The electroless nickel-phosphorus-cobalt plating bath according to claim 2, wherein the propargyl alcohol is ethoxylated and / or propoxylated propargyl alcohol.
The iodide ion source or the iodate ion source is selected from the group consisting of potassium iodide, iron iodide, nickel iodide, lithium iodide, sodium iodide, sodium iodide, potassium iodate, sodium iodate, and ammonium iodate The electroless nickel-phosphorus-cobalt plating bath according to any one of claims 1 to 3, which is at least one type.
The nitro group-containing aromatic compound is at least one selected from the group consisting of benzene having a substituent other than a nitro group, naphthalene having a substituent other than a nitro group, and alkali metal salts thereof. The electroless nickel-phosphorus-cobalt plating bath according to any one of claims 1 to 4.