Electroless nickel plating film, electroless nickel plating bath, and method for producing electroless nickel plating film

Abstract

To provide an electroless nickel plating film that suppresses the occurrence of cracks even at high temperatures of 200°C or higher. [Solution] The electroless nickel plating film has a measured peak intensity ratio of Ni(111) to Ni(220), Ni(111) / Ni(220), of less than 1.0 when analyzed by X-ray diffraction.

Description

[Technical Field]

[0001] The present invention relates to an electroless nickel plating film, an electroless nickel plating bath, and a method for producing an electroless nickel plating film. [Background technology]

[0002] The use of SiC and GaN semiconductors, which can operate at higher temperatures than the Si semiconductors that have been used conventionally, is increasing in power semiconductors. As a result, the operating temperature of power semiconductors is expected to rise to over 200°C, and high heat resistance is being required for the Ni coating obtained by electroless nickel plating used in the joints. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7144048 [Patent Document 2] Patent No. 7560093 Summary of the Invention [Problem to be solved by the invention]

[0004] Known examples of electroless Ni plating that is compatible with high heat resistance include electroless nickel-phosphorus plating formed using an electroless nickel-phosphorus plating bath containing 50 to 200 g / L of a water-soluble nickel compound, a reducing agent that is at least one selected from the group consisting of hypophosphorous acid and hypophosphites, at least one selected from the group consisting of glutamic acid and glutamic acid salts, and at least one selected from the group consisting of phosphorous acid and phosphites (see Patent Document 1), and electroless nickel-phosphorus plating formed using an electroless nickel-phosphorus plating bath that contains a water-soluble nickel compound, a reducing agent, and at least one selected from the group consisting of phosphorous acid and phosphites, in which the content of the reducing agent is 8 g / L or less and the content of the at least one selected from the group consisting of phosphorous acid and phosphites is 30 g / L or more (see Patent Document 2).

[0005] As mentioned above, the operating temperatures of power semiconductors are expected to rise, and the nickel coating obtained by electroless nickel plating used in semiconductor joints must also be able to withstand high temperatures. Specifically, there is a demand for nickel coating that can adequately suppress the occurrence of cracks even at temperatures above 200°C.

[0006] An object of the present invention is to provide an electroless nickel plating film in which the occurrence of cracks is suppressed even at high temperatures of 200°C or higher. [Means for solving the problem]

[0007] The present invention (1) relates to an electroless nickel plating film, in which the measured peak intensity ratio of Ni(111) to Ni(220), Ni(111) / Ni(220), in analysis by X-ray diffraction is less than 1.0.

[0008] The present invention (2) is an electroless nickel plating bath for forming the electroless nickel plating film according to the present invention (1), comprising: The present invention relates to a method for producing a nickel-based solution comprising the steps of: a water-soluble nickel compound; a reducing agent; a complexing agent; a formic acid (salt) as a crystal structure modifier; and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), The electroless nickel plating bath has a pH of 4 to 8. [ka] (In formula (1), R 1 represents a hydrocarbon group which may have a substituent. 1 represents a number greater than or equal to 1.) [ka] (In formula (2), R 2 represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. n 2 represents a number greater than or equal to 1.)

[0009] The present invention (3) relates to the electroless nickel plating bath according to the present invention (2), wherein the concentration of the crystal structure modifier is 0.5 to 30 g / L.

[0010] The present invention (4) relates to the electroless nickel plating bath according to the present invention (2), wherein the reducing agent contains hypophosphorous acid (salt).

[0011] The present invention (5) relates to the electroless nickel plating bath according to the present invention (2), wherein the concentration of the reducing agent is 4 to 16 g / L.

[0012] The present invention (6) relates to the electroless nickel plating bath according to the present invention (2), wherein the complexing agent contains an amino acid.

[0013] The present invention (7) relates to the electroless nickel plating bath according to the present invention (2), wherein the concentration of the complexing agent is 5 to 50 g / L.

[0014] The present invention (8) is a method for forming an electroless nickel plating film, comprising the step of contacting an object to be plated with an electroless nickel plating bath to form an electroless nickel plating film, The electroless nickel plating bath contains a water-soluble nickel compound, a reducing agent, a complexing agent, and at least one of formic acid (salt) as a crystal structure modifier, a compound represented by the following general formula (1), and a compound represented by the following general formula (2): The present invention relates to a method for producing an electroless nickel plating film, which includes a step of forming a plating film at a plating deposition rate of less than 10 μm / h. [ka] (In formula (1), R 1 represents a hydrocarbon group which may have a substituent. 1 represents a number greater than or equal to 1.) [ka] (In formula (2), R2 represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. n 2 represents a number greater than or equal to 1.) [Effects of the Invention]

[0015] According to the present invention, by using a plating bath containing a water-soluble nickel compound, a reducing agent, a complexing agent, and a predetermined compound as a crystal structure modifier, it is possible to produce an electroless nickel plating film with high crack resistance in which the occurrence of cracks is suppressed even when heat treatment is performed at 200°C or higher. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing the evaluation criteria for crack resistance in Examples. [Figure 2] FIG. 1 is a diagram showing an outline of the Erichsen test in the Examples. [Figure 3] FIG. 2 is a diagram showing the results of XRD measurement of the plating film obtained in Example 1-1. [Figure 4] FIG. 2 is a diagram showing the results of XRD measurement of the plating film obtained in Comparative Example 1-1. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Electroless nickel plating film> The electroless nickel plating film of the present invention is characterized in that the peak intensity ratio Ni(111) / Ni(220) measured between Ni(111) and Ni(220) in analysis by X-ray diffraction method is less than 1.0. The plating film formed using the electroless nickel plating bath of the present invention exhibits the above-mentioned characteristic peaks in analysis by X-ray diffraction. The plating film formed using the electroless nickel-phosphorus plating bath described in Patent Document 2 has a peak characteristic of Ni(200), and the electroless nickel plating film of the present invention is different from the plating film described in Patent Document 2. The electroless nickel plating film of the present invention is a plating film that has excellent crack resistance.

[0018] The electroless nickel plating film of the present invention preferably contains phosphorus, and the phosphorus content is less than 3 mass %. When phosphorus is contained, the plating film of the present invention becomes an electroless nickel-phosphorus plating film. If the plating film contains phosphorus and the phosphorus content is less than 3 mass%, the electroless nickel-phosphorus plating film will have better crack resistance. The phosphorus content in the electroless nickel-phosphorus plating film is more preferably 2 mass% or less. The phosphorus content in the electroless nickel-phosphorus plating film can be measured using a wavelength dispersive X-ray fluorescence analyzer.

[0019] The thickness of the electroless nickel plating film of the present invention is not particularly limited, but is preferably, for example, 1 to 50 μm, more preferably 1 to 20 μm, and even more preferably 1 to 10 μm. In this specification, the thickness of the electroless nickel plating film is a value calculated by the following gravimetric method. [Gravimetric method] The weights before and after the electroless nickel plating treatment were measured using an analytical electronic balance (Shimadzu AW120). The difference in weight before and after the electroless nickel plating treatment and the specific gravity of nickel (8.76 g / cm) were calculated. 3 ) to calculate the film thickness.

[0020] <Electroless nickel plating bath> The electroless nickel plating bath of the present invention contains a water-soluble nickel compound, a reducing agent, a complexing agent, and at least one of formic acid (salt) as a crystal structure modifier, a compound represented by the following general formula (1), and a compound represented by the following general formula (2), and has a pH of 4 to 8. [ka] (In formula (1), R 1 represents a hydrocarbon group which may have a substituent. 1 represents a number greater than or equal to 1.) [ka] (In formula (2), R 2 represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. n 2 represents a number greater than or equal to 1.) It has been confirmed that electroless nickel plating films formed using such a plating bath exhibit less structural changes, such as crystal orientation and crystal size, even when subjected to heat treatment than plating films formed using conventional plating baths. By performing electroless nickel plating using this plating bath, it is possible to produce electroless nickel plating films in which the occurrence of cracks is suppressed even when subjected to heat treatment at 200°C or higher.

[0021] The water-soluble nickel compound contained in the electroless nickel plating bath of the present invention may be an inorganic salt or an organic acid salt of nickel. Examples of inorganic and organic salts of nickel include nickel sulfate, nickel chloride, nickel hypophosphite, nickel carbonate, nickel acetate, nickel malate, and hydrates thereof. One or more of these can be used.

[0022] The concentration of the water-soluble nickel compound in the electroless nickel plating bath of the present invention is preferably 1 to 10 g / L in terms of nickel concentration. By including the water-soluble nickel compound at such a concentration, it is possible to form an electroless nickel plating film with excellent crack resistance while adequately controlling the nickel concentration and avoiding high costs. The nickel concentration in the plating bath of the present invention is more preferably 1 to 10 g / L, and even more preferably 3 to 7 g / L.

[0023] Examples of reducing agents contained in the electroless nickel plating bath of the present invention include hypophosphorous acid (salts), phosphorous acid (salts), hydrazine derivatives, formaldehyde compounds, hydroxylamines, sugars, boron hydride compounds, dimethylamine borane, and ascorbic acid, and one or more of these can be used. When the electroless nickel plating bath of the present invention contains a hypophosphite or a phosphite, salts of alkali metals such as sodium and potassium; alkaline earth metals such as calcium; ammonium salts, etc. can be used. When the electroless nickel plating bath of the present invention contains a hypophosphite and a phosphite, the electroless nickel plating bath can be called an electroless nickel-phosphorus plating bath. Although formic acid (salts), compounds represented by general formula (1), and compounds represented by general formula (2) also function as reducing agents, the term "reducing agent" in the present invention means "a reducing agent other than formic acid (salts), compounds represented by general formula (1), and compounds represented by general formula (2)."

[0024] The electroless nickel plating bath of the present invention preferably contains hypophosphorous acid (salt) as a reducing agent. By including hypophosphorous acid (salt), the electroless nickel plating film (electroless nickel-phosphorus plating film) formed will have better crack resistance. Among hypophosphorous acid (salts), sodium hypophosphite monohydrate is more preferred.

[0025] The concentration of the reducing agent in the electroless nickel plating bath of the present invention is preferably 4 to 16 g / L. When the reducing agent is contained at such a concentration, an electroless nickel plating film with excellent crack resistance can be formed at a good deposition rate while avoiding high costs. The concentration of the reducing agent in the plating bath of the present invention is more preferably 7 to 14 g / L.

[0026] The complexing agent contained in the electroless nickel plating bath of the present invention is not particularly limited as long as it is a compound capable of stably dissolving nickel ions. Specific examples thereof include amino acids (salts), amide compounds, imide compounds, sulfur-containing organic compounds, and nitrogen-containing compounds (nitrogen-containing compounds other than amide compounds and imide compounds). These may be used alone or in combination of two or more.

[0027] In the electroless nickel plating bath of the present invention, the complexing agent preferably contains an amino acid (salt), which can prevent the plating bath from becoming cloudy. Examples of amino acids include glycine, alanine, lysine, glutamine, glutamic acid, asparagine, and aspartic acid. Examples of amino acid salts include alkali metal salts such as sodium and potassium; alkaline earth metal salts such as calcium; and ammonium salts.

[0028] The concentration of the complexing agent in the electroless nickel plating bath of the present invention is preferably 5 to 50 g / L. When the complexing agent is contained at such a concentration, an electroless nickel plating film with excellent crack resistance can be formed at a good deposition rate while suppressing the formation of precipitates such as nickel hydroxide and nickel phosphite in the plating bath. Because nickel phosphite is a substance that causes cracks, suppressing the formation of nickel phosphite allows the formation of an electroless nickel-phosphorus plating film with even better crack resistance. The concentration of the complexing agent in the plating bath of the present invention is more preferably 12 to 45 g / L, and even more preferably 20 to 40 g / L.

[0029] The electroless nickel plating bath of the present invention contains, as a crystal structure modifier, at least one of formic acid (salt), a compound represented by the above general formula (1), and a compound represented by the above general formula (2). n in the above general formula (1) 1 and n in the above general formula (2) 2 If is 1, R 1 , R 2 Examples of the monovalent hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. The monovalent hydrocarbon group may have a linear or branched chain structure, a cyclic structure, or a structure combining a chain structure and a cyclic structure. The cyclic structure may be an alicyclic structure or an aromatic ring. R 1 , R 2 The hydrocarbon group preferably has 1 to 5 carbon atoms, and more preferably has 1 to 3 carbon atoms. n in the above general formula (1) 1 and n in the above general formula (2) 2 If is 2 or more, R 1 , R 2 The hydrocarbon group may be any of the monovalent hydrocarbon groups listed above. 1 and 2 Examples of the hydrocarbon groups include divalent or higher hydrocarbon groups obtained by removing hydrogen atoms according to the number of groups.

[0030] R in the above general formula (1) 1 , R in general formula (2) 2 When the hydrocarbon group has a substituent, examples of the substituent include a halogen atom such as a chlorine atom or a fluorine atom; a hydroxyl group; a carboxyl group; a cyano group; a sulfonic acid group; a phosphate group; an alkoxy group; a -C(=O)-R group (ketone group), a nitro group, an amino group, an ether bond-containing group (-OR group), an amide bond-containing group (-NHC(=O)-R), an ester bond-containing group (-COO-R), etc. R in the ketone group, ether bond-containing group, amide bond-containing group, and ester bond-containing group represents a monovalent hydrocarbon group, and examples of the monovalent hydrocarbon group include R in the above general formula (1). 1 and R in the above general formula (2) 2 The monovalent hydrocarbon groups are the same as those mentioned above. R in the above general formula (1) 1 , R in general formula (2) 2 When the hydrocarbon group has a substituent, it may have only one substituent or two or more substituents.

[0031] n in the above general formula (1) 1 and n in the above general formula (2) 2 is 1 or more, preferably 1 to 5, and more preferably 1 to 3. Examples of the metal atom Z in the general formula (2) include alkali metal atoms such as sodium and potassium.

[0032] Examples of the compound represented by the general formula (1) include alkyl esters of formic acid such as methyl formate, ethyl formate, isobutyl formate, and amyl formate; alkyl esters of formic acid having a substituent such as cyanomethyl formate; alkenyl esters of formic acid; bisformate esters such as ethylene bisformate, 3-formyloxypropyl formate, and 1,2-propanediol diformate; and triformate esters of formic acid such as glycerol triformate.

[0033] Examples of the compound represented by the above general formula (2) include pyruvic acid; trimethylpyruvic acid, phenylpyruvic acid, 2,4-dioxopentanoic acid, 3,4-dihydroxyphenylpyruvic acid, and 3-bromopyruvic acid.

[0034] The concentration of the crystal structure modifier in the electroless nickel plating bath of the present invention is preferably 0.5 to 30 g / L. By including the crystal structure modifier at such a concentration, a Ni coating having excellent crack resistance can be obtained, in which the peak intensity ratio Ni(111) / Ni(220) measured by X-ray diffraction method between Ni(111) and Ni(220) in the crystal structure is less than 1.0. The concentration of the crystal structure modifier in the electroless nickel plating bath of the present invention is more preferably 3 to 20 g / L, and even more preferably 5 to 10 g / L.

[0035] The electroless nickel plating bath of the present invention may contain a carboxylic acid (salt), which makes it possible to adjust the deposition rate of the electroless nickel coating. Examples of the carboxylic acid include adipic acid, oxalic acid, malonic acid, succinic acid, gluconic acid, and citric acid. Examples of the salts of carboxylic acids include salts of alkali metals such as sodium and potassium; salts of alkaline earth metals such as calcium; and ammonium salts.

[0036] When the electroless nickel plating bath of the present invention contains a carboxylic acid (salt), the concentration of the carboxylic acid (salt) is preferably 1 to 50 g / L, more preferably 3 to 35 g / L, and even more preferably 5 to 20 g / L.

[0037] The electroless nickel plating bath of the present invention may contain a stabilizer, which can prevent decomposition of the plating bath. tin compounds such as tin sulfate and tin chloride; selenium compounds such as selenic acid and selenious acid; cyanides such as methyl cyanide and isopropyl cyanide; and allyl compounds such as allylamine and diallylamine.

[0038] When the electroless nickel plating bath of the present invention contains a stabilizer, the concentration of the stabilizer is preferably 0.01 to 100 mg / L. At such a concentration, a plating film can be formed while maintaining the plating bath stability. The concentration is more preferably 0.05 to 50 mg / L, and even more preferably 0.1 to 10 mg / L.

[0039] The electroless nickel plating bath of the present invention may further contain other components in addition to those described above, such as sulfur compounds and surfactants. Examples of sulfur compounds include compounds commonly used as sulfur additives for electroless nickel, such as thiosulfuric acid or its salts (e.g., sodium salts), thioglycolic acid, thiodiglycolic acid, thiourea, and thiocyanic acid bases. As the surfactant, various surfactants can be used, such as nonionic, anionic, cationic, amphoteric, etc. Examples thereof include alkali salts of aromatic or aliphatic sulfonic acids, and alkali metal salts of aromatic or aliphatic carboxylic acids. These may be used alone or in combination of two or more.

[0040] The content of other components in the electroless nickel plating bath of the present invention other than those described above is preferably 1000 mg / L or less, more preferably 500 mg / L or less, and even more preferably 200 mg / L or less.

[0041] The electroless nickel plating bath of the present invention contains water as a solvent.

[0042] The electroless nickel plating bath of the present invention has a pH of 4 to 8. This pH allows the plating bath to be kept stable and effectively prevents uneven appearance of the plated film that is formed. The pH of the plating bath is preferably 5 to 7. The pH of the plating bath can be adjusted by adding an acid or a base to the plating bath.

[0043] <Method of manufacturing electroless nickel plating film> The method for producing an electroless nickel plating film of the present invention is a method for forming an electroless nickel plating film, comprising the steps of bringing an object to be plated into contact with an electroless nickel plating bath to form an electroless nickel plating film, The electroless nickel plating bath contains a water-soluble nickel compound, a reducing agent, a complexing agent, and at least one of formic acid (salt) as a crystal structure modifier, a compound represented by the following general formula (1), and a compound represented by the following general formula (2): The method for producing an electroless nickel-phosphorus plating film includes a step of forming a plating film at a plating deposition rate of less than 10 μm / h. [ka] (In formula (1), R 1 represents a hydrocarbon group which may have a substituent. 1 represents a number greater than or equal to 1.) [ka] (In formula (2), R 2represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. n 2 represents a number greater than or equal to 1.) Thus, a plated film formed using the electroless nickel plating bath of the present invention at a plating deposition rate of less than 10 μm / h is an electroless nickel plated film with excellent crack resistance in which cracks are suppressed even in heat treatment at 400°C or higher and in a thermal cycle test in which the temperature is changed between 250°C and −50°C.

[0044] In the method for producing an electroless nickel plating film of the present invention, the plating deposition rate needs only to be less than 10 μm / h, but in order to form an electroless nickel plating film with sufficiently excellent crack resistance as efficiently as possible, it is preferably 0.5 to 9 μm / h, and more preferably 1 to 6 μm / h. The concentration of the reducing agent contained in the electroless nickel plating bath affects the deposition rate of the plating, and the higher the concentration, the faster the deposition rate tends to be. The deposition rate of electroless nickel also tends to increase by increasing the reducing agent concentration, temperature, and nickel concentration, or by decreasing the complexing agent concentration.

[0045] In the method for producing an electroless nickel plating film of the present invention, the temperature at which the step of forming the plating film is carried out is not particularly limited as long as the plating film is formed, but is preferably 30 to 100°C. By carrying out the step of forming the plating film at such a temperature, it is possible to form a plating film with excellent heat resistance with good productivity while maintaining the stability of the plating bath. The temperature at which the step of forming the plating film is carried out is more preferably 70 to 100°C, and even more preferably 80 to 95°C.

[0046] In the method for producing an electroless nickel plating film of the present invention, the time for performing the step of forming the plating film may be adjusted appropriately depending on the size of Cu, Al, Fe and their alloys, resin, and glass substrate, the thickness of the plating film to be formed, and the like. The time for the process of forming the plating film can be determined in accordance with the desired thickness of the plating film, for example, by immersing the substrate in a plating bath for a predetermined time in advance and confirming the relationship between plating time and film thickness from the thickness of the formed plating film.

[0047] The method for producing an electroless nickel plating film of the present invention may include other steps in addition to the step of forming the plating film. Examples of such other steps include a pretreatment step. In the pretreatment step, it is preferable to select an appropriate treatment from among cleaning, pickling, etching, activator treatment, zincate treatment, dismutation treatment, and the like, depending on the type of substrate.

[0048] In the method for producing an electroless nickel plating film of the present invention, the substrate on which the plating film is formed is not particularly limited, and Cu, Al, Fe, alloys thereof, resin, glass, etc. can be used. Furthermore, the electroless nickel plating film produced by the method for producing an electroless nickel plating film of the present invention can be used as a bonding portion of a semiconductor substrate. In this case, examples of the semiconductor substrate include DBC substrates, DBA substrates, and AMB substrates. Here, DBC stands for Direct Bonded Copper, DBA stands for Direct Bonded Aluminum, and AMB stands for Active Metal Brazing.

[0049] The processing conditions and various concentration settings in the above-described processing are not limited to the above conditions, and it goes without saying that they can be changed as appropriate depending on the thickness of the film to be formed, etc. Furthermore, after the electroless nickel plating film of the present invention is formed on the substrate, a plating film of another metal, such as an electroless gold plating film, an electroless palladium plating film, or an electroless silver plating film, may be formed thereon. That is, after the electroless nickel plating film is formed on the substrate using the method for producing an electroless nickel plating film of the present invention, a step of forming a plating film of another metal, such as an electroless gold plating film, an electroless palladium plating film, or an electroless silver plating film, may be carried out. As long as an electroless nickel plating film is formed by the method for producing an electroless nickel plating film of the present invention, even if a step of forming a plating film of another metal such as an electroless gold plating film, an electroless palladium plating film, or an electroless silver plating film is performed thereafter, it is included in the technical scope of the method for producing an electroless nickel plating film of the present invention.

[0050] The electroless nickel film of the present invention is a nickel film excellent in crack resistance with crack generation suppressed even under large temperature changes or high-temperature environments, and is optimal for joining power semiconductors with high operating temperatures.

Example

[0051] The present invention will be specifically described based on examples, but the present invention is not limited thereto.

[0052] Various measurements were performed as follows. <pH measurement> The adjusted plating solution was measured at room temperature (25 °C) using a pH meter (HM-41X manufactured by Toa DKK Corporation). <Crack resistance evaluation> (Indentation test using an Erichsen tester) The electroless nickel-phosphorus plating film formed on an iron plate as in the following examples and comparative examples was heat-treated at a predetermined temperature for 30 minutes. After heat treatment, the electroless nickel-phosphorus plating film was indented by 0.5 mm with an Erichsen tester, and the state of cracks generated on the convex side of the electroless nickel-phosphorus plating film after indentation was confirmed at a magnification of 80 times using a digital microscope (VHX-7000 manufactured by Keyence Corporation). <Deposition rate measurement> The film thickness was calculated from the weight difference and density before and after plating, and the deposition rate (μm / hr) was determined. <Analysis of P content in the plating film> The phosphorus content rate contained in the formed electroless nickel-phosphorus plating film was measured using a wavelength dispersive fluorescent X-ray analyzer (ZSX PrimusIV manufactured by Rigaku Corporation). <Hardness of the plating film> (Vickers hardness measurement) The electroless nickel-phosphorus plating film formed was heat-treated by heating at 400 °C for 30 minutes, and the Vickers hardness of the surface of the electroless nickel-phosphorus plating film before and after the heat treatment was measured at room temperature (25 °C) using a micro-Vickers hardness tester (HM-200B manufactured by Mitutoyo Corporation) (load 0.1 Kg). (XRD measurement) (Analysis by X-ray diffraction method (XRD analysis)) XRD analysis was performed on the electroless nickel-phosphorus plating film formed on the iron plate as described above using an XRD measuring device (SmartLab manufactured by Rigaku Corporation).

[0053] Example 1-1 Using the electroless nickel plating bath prepared as described in Table 1, with the iron plate as the plating object, the plating object was immersed in the electroless nickel plating bath at a bath temperature of 90 °C for a predetermined time to form an electroless nickel plating film with a film thickness of 3 to 5 μm. In Table 1, regarding the concentration of the water-soluble Ni compound, the concentration of nickel sulfate hexahydrate and the concentration of nickel contained in nickel sulfate hexahydrate were described. The same applies to Tables 2 to 5. The deposition rate was measured, and for the obtained electroless nickel-phosphorus plating film, crack resistance evaluation, P content measurement, and hardness measurement were performed. Also, the measured peak intensity ratio Ni(111) / Ni(220) between Ni(111) and Ni(220) of the obtained electroless nickel-phosphorus plating film was confirmed. The results are shown in Table 1. The XRD measurement results of the electroless nickel-phosphorus plating film obtained in Example 1-1 are shown in Figure 3.

[0054] Examples 1-2 to 1-10, Comparative Example 1-1 Electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1, except that the composition of the plating bath used was changed as shown in Table 1. The deposition rate was measured in the same manner as in Example 1-1, and the resulting electroless nickel-phosphorus plating film was evaluated for crack resistance, measured for P content, and measured for hardness. In addition, the peak intensity ratio Ni(111) / Ni(220) of the resulting electroless nickel-phosphorus plating film between Ni(111) and Ni(220) was determined. The results are shown in Table 1. In addition, XRD measurement was performed on the electroless nickel-phosphorus plating film obtained in Comparative Example 1-1. The results are shown in Figure 4.

[0055] [Table 1]

[0056] In the examples and comparative examples, crack resistance was evaluated under severe heat treatment conditions of 350°C or higher, and samples in which no cracks were observed were marked with a circle, and samples in which cracks were observed were marked with an x. The results in Table 1 confirm that by using a plating bath containing formic acid or a formate salt as a crystal structure modifier, an electroless nickel-phosphorus plating film with excellent crack resistance can be obtained even after heat treatment at 350°C. Furthermore, it was confirmed that the plated films obtained using a plating bath containing formic acid or a formate as a crystal structure modifier have a measured peak intensity ratio of Ni(111) to Ni(220), Ni(111) / Ni(220), of less than 1.0, whereas the plated films obtained using a plating bath containing no formic acid or a formate have a Ni(111) / Ni(220) ratio of greater than 1.0.

[0057] Examples 2-1 to 2-7 (Confirmation of the effect of deposition rate) Electroless nickel-phosphorus plating was carried out in the same manner as in Example 1-1, except that an iron plate was used as the substrate and the plating bath composition used was as shown in Table 2. The crack resistance of the resulting electroless nickel-phosphorus plating film was evaluated, and the P content was measured. In addition, the peak intensity ratio of Ni(111) to Ni(220) of the resulting electroless nickel-phosphorus plating film, Ni(111) / Ni(220), was determined. The results are shown in Table 2.

[0058] [Table 2]

[0059] Examples 2-1 to 2-5 are examples in which the deposition rate of plating was changed by adjusting the concentration of the reducing agent (sodium hypophosphite monohydrate). It was confirmed that plating films with excellent crack resistance could be obtained even with heat treatment at 350°C up to a deposition rate of 9.5 μm / hr, and that plating films with excellent crack resistance could be obtained even with heat treatment at higher temperatures by further slowing the deposition rate. Furthermore, when Example 2-4 is compared with Example 2-6, in which the deposition rate was changed by adjusting the concentrations of other components while keeping the reducing agent concentration the same as in Example 2-4, Example 2-6, which has a slower deposition rate, yields a plated film with excellent crack resistance even at higher heat treatment temperatures. Furthermore, when Example 2-1 is compared with Example 2-7, in which the reducing agent concentration is the same as in Example 2-1 but the amount of carboxylic acid added is set to 0, Example 2-1, which has a slower deposition rate, yields a plated film with excellent crack resistance even at higher heat treatment temperatures. These comparisons confirm that the deposition rate has a significant effect on the crack resistance of plated films. In all of Examples 2-1 to 2-7, it was confirmed that the plated films obtained had a measured peak intensity ratio of Ni(111) to Ni(220), Ni(111) / Ni(220), of less than 1.0.

[0060] Examples 3-1 to 3-6, Comparative Examples 3-1 to 3-3 (pH change) Electroless nickel-phosphorus plating was carried out in the same manner as in Example 1-1, except that the composition of the plating bath used was changed as shown in Table 3. The deposition rate was measured in the same manner as in Example 1-1, and the crack resistance and P content of the resulting electroless nickel-phosphorus plating film were evaluated. In addition, the peak intensity ratio Ni(111) / Ni(220) of the resulting electroless nickel-phosphorus plating film between Ni(111) and Ni(220) was determined. The results are shown in Table 3.

[0061] [Table 3]

[0062] Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-3 are examples in which the pH of the plating bath was changed. Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-3 confirmed that the pH of the plating bath must be 4 to 8 in order to obtain a plating film that has excellent crack resistance even after high-temperature heat treatment at 350°C. For the plated films of Examples 3-1 to 3-6, in which a plating bath with a pH of 4 to 8 was used, the Ni(111) / Ni(220) ratio was less than 1.0, whereas for the plated films of Comparative Examples 3-1 to 3-3, in which a plating bath with a pH of less than 4 or more than 8 was used, either no plated film was formed or the Ni(111) / Ni(220) ratio was 1.0 or greater.

[0063] Examples 4-1 to 4-3 (changing the complexing agent) Electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1, except that the composition of the plating bath used was changed as shown in Table 4. The deposition rate was measured in the same manner as in Example 1-1, and the crack resistance and P content of the resulting electroless nickel-phosphorus plating film were evaluated. In addition, the peak intensity ratio Ni(111) / Ni(220) of the resulting electroless nickel-phosphorus plating film between Ni(111) and Ni(220) was determined. The results are shown in Table 4.

[0064] [Table 4]

[0065] Examples 4-1 to 4-3 are examples in which the complexing agent in the plating bath was changed. Examples 4-1 to 4-3 confirmed that a plating film with excellent crack resistance could be obtained even with a high-temperature heat treatment at 350°C, regardless of the type of complexing agent. In all of the plating films of Examples 4-1 to 4-3, the Ni(111) / Ni(220) ratio was less than 1.0.

[0066] Examples 5-1 to 5-5, Comparative Examples 5-1 to 5-9 (Changes in Crystal Structure Modifier) Electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1, except that the composition of the plating bath used was changed as shown in Table 5. The deposition rate was measured in the same manner as in Example 1-1, and the crack resistance and P content of the resulting electroless nickel-phosphorus plating film were evaluated. In addition, the peak intensity ratio Ni(111) / Ni(220) of the resulting electroless nickel-phosphorus plating film between Ni(111) and Ni(220) was determined. The results are shown in Table 5.

[0067] [Table 5]

[0068] Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-9 are examples in which the crystal structure modifier in the plating bath was changed. In Examples 5-1 to 5-5, in which formic acid (salt), a compound represented by general formula (1), or a compound represented by general formula (2) was used as the crystal structure modifier, it was confirmed that a plating film with excellent crack resistance could be obtained even after a high-temperature heat treatment at 350°C. On the other hand, in Comparative Examples 5-1 to 5-9, in which a compound other than formic acid (salt), a compound represented by general formula (1), or a compound represented by general formula (2) was used, cracks occurred in the resulting plating film after a high-temperature heat treatment at 350°C (Comparative Examples 5-1 to 5-4, 5-7 to 5-9), or the plating bath decomposed, resulting in no plating film being formed (Comparative Examples 5-5 and 5-6). From Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-9, it was confirmed that in order to obtain a plating film having excellent crack resistance even after a high-temperature heat treatment at 350°C, it is necessary to use any one of formic acid (salt), a compound represented by general formula (1), and a compound represented by general formula (2) as a crystal structure modifier for the plating bath. In the plating films of Examples 5-1 to 5-5, in which formic acid (salt), a compound represented by general formula (1), or a compound represented by general formula (2) was used as a crystalline structure modifier for the plating bath, the Ni(111) / Ni(220) ratio was less than 1.0. In Comparative Examples 5-1 to 5-9, in which a compound other than these was used as a crystalline structure modifier for the plating bath, either no plating film was formed, or, even if a plating film was formed, the Ni(111) / Ni(220) ratio was 1.0 or more.

[0069] The results in Tables 1 to 5 demonstrate that by using the plating bath of the present invention and setting the deposition rate at less than 10 μm / h, a plating film with excellent crack resistance can be obtained even under high-temperature conditions. The plating film of the present invention is a plating film that has a characteristic peak in which the peak intensity ratio between Ni(111) and Ni(220), Ni(111) / Ni(220), measured by X-ray diffraction analysis, is less than 1.0. The method for producing an electroless nickel plating film using the plating bath of the present invention is useful for applications requiring high heat resistance, such as the junctions of power semiconductors.

Claims

1. An electroless nickel plating film (excluding those containing manganese, zinc, and silver as metal components) in which the measured peak intensity ratio Ni(111) / Ni(220) of Ni(111) to Ni(220) in analysis by X-ray diffraction method is less than 1.

0.

2. 2. An electroless nickel plating bath for forming the electroless nickel plating film according to claim 1, comprising: The present invention relates to a method for producing a nickel-based aqueous solution of nickel oxide, a nickel-based aqueous solution of nickel oxide, a nickel-based aqueous solution of nickel oxide, and a nickel-based aqueous solution of nickel oxide. pH is 4 to 8, An electroless nickel plating bath having a complexing agent concentration of 5 to 50 g / L. 【Chemical 1】 (In formula (1), R １ represents a hydrocarbon group which may have a substituent. １ represents a number greater than or equal to 1.) 【Chemistry 2】 (In formula (2), R ２ represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. ２ represents a number greater than or equal to 1.)

3. 3. The electroless nickel plating bath according to claim 2, wherein the concentration of the crystal structure modifier is 0.5 to 30 g / L.

4. 3. The electroless nickel plating bath according to claim 2, wherein the reducing agent comprises hypophosphorous acid (salt).

5. 3. The electroless nickel plating bath according to claim 2, wherein the concentration of the reducing agent is 4 to 16 g / L.

6. The electroless nickel plating bath according to claim 2 , wherein the complexing agent comprises an amino acid.

7. A method for forming an electroless nickel plating film, comprising the step of contacting an object to be plated with an electroless nickel plating bath to form an electroless nickel plating film, The electroless nickel plating bath contains a water-soluble nickel compound, a reducing agent, a complexing agent, and at least one of formic acid (salt) as a crystal structure modifier, a compound represented by the following general formula (1), and a compound represented by the following general formula (2): The concentration of the complexing agent is 5 to 50 g / L; The concentration of the crystal structure modifier is 0.5 to 30 g / L; pH is 4 to 8, A method for producing an electroless nickel plating film, comprising the step of forming a plating film at a plating deposition rate of less than 10 μm / h. 【Chemistry 3】 (In formula (1), R １ represents a hydrocarbon group which may have a substituent. １ represents a number greater than or equal to 1.) 【Chemistry 4】 (In formula (2), R ２ represents a hydrocarbon group which may have a substituent. Z represents a hydrogen atom or a metal atom. ２ represents a number greater than or equal to 1.)

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