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

Abstract

Provided is an electrolytic nickel plating film that can suppress the generation of cracks even at high temperatures of 200°C or higher. An electrolytic nickel plating film characterized in that the ratio of the measured peak intensity of Ni(111) to that of Ni(220), Ni(111) / Ni(220), in analysis by X-ray diffraction method is less than 1.0.

Description

Technical Field

[0001] This invention relates to an electroless nickel plating film, an electroless nickel plating bath, and a method for manufacturing an electroless nickel plating film. Background Technology

[0002] In power semiconductors, the application of SiC or GaN semiconductors, which can operate at higher temperatures compared to the previously used Si semiconductors, is continuously advancing. As a result, the operating temperature of power semiconductors is expected to rise to over 200°C. Therefore, the Ni film obtained by electroless nickel plating used in the junction also requires high heat resistance.

[0003] [Existing technical documents]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent No. 7144048

[0006] [Patent Document 2] Japanese Patent No. 7560093 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] As a solution for high heat resistance electroless nickel plating, the following technologies are known: an electroless nickel plating using an electroless nickel-phosphorus plating bath, the plating bath containing: a water-soluble nickel compound, a reducing agent selected from at least one of hypophosphorous acid and hypophosphite, at least one of glutamic acid and glutamate, and 50-200 g / L of at least one of phosphorous acid and phosphite (see Patent Document 1); and an electroless nickel plating using an electroless nickel-phosphorus plating bath, the plating bath containing a water-soluble nickel compound, a reducing agent, and at least one of phosphorous acid and phosphite, wherein the content of the reducing agent is 8 g / L or less, and the content of at least one of phosphorous acid and phosphite is 30 g / L or more (see Patent Document 2).

[0009] As mentioned above, it is foreseeable that the operating temperature of power semiconductors will increase, therefore the nickel film obtained by electroless nickel plating for semiconductor junctions must also be able to withstand high temperatures. Specifically, a nickel film that can sufficiently suppress crack formation even at temperatures above 200°C is required.

[0010] The purpose of this invention is to provide an electroless nickel plating film that can suppress crack formation even at high temperatures above 200°C.

[0011] Technical solutions to the problem

[0012] The present invention (1) relates to an electroless nickel plating film, characterized in that the ratio of the measured peak intensity of Ni (111) to Ni (220) in the electroless nickel plating film by X-ray diffraction is less than 1.0.

[0013] This invention (2) relates to an electroless nickel plating bath for forming the electroless nickel plating film described in this invention (1).

[0014] The electroless nickel plating bath contains: a water-soluble nickel compound, a reducing agent, a complexing agent, and, as a crystal structure modifier, any one or more of the following: formic acid (salt), a compound represented by the following general formula (1), and a compound represented by the following general formula (2).

[0015] The pH of the electroless nickel plating bath is 4–8;

[0016]

Chemistry 1

[0017]

[0018] (In equation (1), R) 1 Indicates a hydrocarbon group with or without substituents. 1 (Represents numbers greater than 1.)

[0019]

Chemistry 2

[0020]

[0021] (In equation (2), R) 2 Indicates a hydrocarbon group with or without substituents. Z represents a hydrogen atom or a metal atom. n 2 (Represents numbers greater than 1.)

[0022] The present invention (3) relates to the electroless nickel plating bath described in the present invention (2), wherein the concentration of the crystal structure modifier is 0.5 to 30 g / L.

[0023] This invention (4) relates to the electroless nickel plating bath described in this invention (2), wherein the reducing agent comprises hypophosphite (salt).

[0024] The present invention (5) relates to the electroless nickel plating bath described in the present invention (2), wherein the concentration of the reducing agent is 4 to 16 g / L.

[0025] This invention (6) relates to the electroless nickel plating bath described in this invention (2), wherein the complexing agent comprises amino acids.

[0026] The present invention (7) relates to the electroless nickel plating bath described in the present invention (2), wherein the concentration of the complexing agent is 5 to 50 g / L.

[0027] This invention (8) relates to a method for manufacturing an electroless nickel plating film, comprising the step of contacting the object to be plated with an electroless nickel plating bath to form an electroless nickel plating film.

[0028] The electroless nickel plating bath contains: a water-soluble nickel compound, a reducing agent, a complexing agent, and, as a crystal structure modifier, any one or more selected from formic acid (salt), a compound represented by the following general formula (1), and a compound represented by the following general formula (2).

[0029] The manufacturing method includes a step of forming a coating at a deposition rate of less than 10 μm / h.

[0030]

Transformation 3

[0031]

[0032] (In equation (1), R) 1 Indicates a hydrocarbon group with or without substituents. 1 (Represents numbers greater than 1.)

[0033]

Chemistry 4

[0034]

[0035] (In equation (2), R) 2 Indicates a hydrocarbon group with or without substituents. Z represents a hydrogen atom or a metal atom. n 2 (Represents numbers greater than 1.)

[0036] [The effects of the invention]

[0037] According to the present invention, by using a plating bath containing a water-soluble nickel compound, a reducing agent, a complexing agent, and a specific compound as a crystal structure modifier, it is possible to manufacture an electroless nickel plating film with high crack resistance that can suppress crack formation even when subjected to heat treatment at temperatures above 200°C. Attached Figure Description

[0038]

【 Figure 1 The figure shown is a diagram illustrating the crack resistance evaluation criteria in the embodiments.

[0039]

【 Figure 2 The figure shown is a summary of the Erichsen cup test in the embodiments.

[0040]

【 Figure 3 The figure shown is a graph representing the XRD measurement results of the coating obtained in Example 1-1.

[0041]

【 Figure 4 The figure shown is the XRD measurement results of the coating obtained in Comparative Example 1-1. Detailed Implementation

[0042] Electroless Nickel Plating Film

[0043] The electroless nickel plating film of the present invention is characterized in that, in the analysis by X-ray diffraction, the ratio of the measured peak intensity of Ni (111) and Ni (220) is less than 1.0.

[0044] The coating formed using the electroless nickel plating bath of the present invention exhibits the aforementioned characteristic peaks in X-ray diffraction analysis. The coating formed using the electroless nickel-phosphorus plating bath described in Patent Document 2 has a characteristic peak at Ni(200), while the electroless nickel plating film of the present invention differs from the coating described in Patent Document 2.

[0045] The electroless nickel plating film of the present invention is a film with excellent crack resistance.

[0046] Preferably, the electroless nickel plating film of the present invention contains phosphorus, and the phosphorus content is less than 3% by mass. When phosphorus is present, the coating of the present invention becomes an electroless nickel-phosphorus coating.

[0047] When the coating contains phosphorus but the phosphorus content is less than 3% by mass, the crack resistance of the electroless nickel-phosphorus coating becomes even better. More preferably, the phosphorus content in the electroless nickel-phosphorus coating is less than 2% by mass.

[0048] The phosphorus content in electroless nickel-phosphorus coatings can be determined using wavelength dispersive X-ray fluorescence spectrometry.

[0049] While the thickness of the electroless nickel plating film of the present invention is not particularly limited, it is preferably 1 to 50 μm, for example. More preferably, it is 1 to 20 μm, and even more preferably, it is 1 to 10 μm.

[0050] In this specification, the thickness of the electroless nickel plating film is calculated using the following gravimetric method.

[0051] [Weight Method]

[0052] The weights of the nickel plating before and after electroless plating were determined using an analytical electronic balance (Shimadzu AW120). The film thickness was calculated based on the weight difference before and after electroless plating and the specific gravity of nickel (8.76 g / cm³).

[0053] Electroless Nickel Plating Bath

[0054] The electroless nickel plating bath of the present invention is an electroless nickel plating bath containing a water-soluble nickel compound, a reducing agent, a complexing agent, and one or more of formic acid (salt), a compound represented by the following general formula (1), and a compound represented by the following general formula (2) as a crystal structure regulator, and having a pH of 4 to 8.

[0055]

Chemistry 1

[0056]

[0057] (In equation (1), R) 1 Indicates a hydrocarbon group with or without substituents. 1 (Represents numbers greater than 1.)

[0058]

Chemistry 2

[0059]

[0060] (In equation (2), R) 2 Indicates a hydrocarbon group with or without substituents. Z represents a hydrogen atom or a metal atom. n 2 (Represents numbers greater than 1.)

[0061] It has been confirmed that, compared to coatings formed using conventional plating baths, electroless nickel plating films formed using this type of plating bath can suppress structural changes such as crystal orientation and crystal size, even after heat treatment. By using this plating bath for electroless nickel plating, it is possible to manufacture electroless nickel plating films that suppress crack formation even after heat treatment at temperatures above 200°C.

[0062] As the water-soluble nickel compound contained in the electroless nickel plating bath of the present invention, an inorganic salt or organic acid salt of nickel can be used.

[0063] Examples of inorganic or organic salts of nickel include nickel sulfate, nickel chloride, nickel hypophosphite, nickel carbonate, nickel acetate, nickel malate, and their hydrates. One or more of these may be used.

[0064] 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, based on the nickel concentration. By containing the water-soluble nickel compound at this concentration, it is possible to effectively manage the nickel concentration while avoiding high costs and forming an electroless nickel plating film with excellent crack resistance. 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.

[0065] Examples of reducing agents included in the electroless nickel plating bath of the present invention include hypophosphite, phosphorous acid, hydrazine derivatives, formaldehyde compounds, hydroxylamines, sugars, borohydrides, dimethylamine borane, ascorbic acid, etc., and one or more of these can be used.

[0066] When the electroless nickel plating bath of the present invention contains hypophosphite and phosphite, alkali metal salts such as sodium and potassium; alkaline earth metal salts such as calcium; ammonium salts, etc., can be used.

[0067] When the electroless nickel plating bath of the present invention contains hypophosphite and phosphite, the electroless nickel plating bath can be called an electroless nickel-phosphorus plating bath.

[0068] It should be noted that although formic acid (salt), compounds represented by general formula (1) and compounds represented by general formula (2) also have the function of being reducing agents, the "reducing agent" in this invention refers to "reducing agents other than formic acid (salt), compounds represented by general formula (1) and compounds represented by general formula (2)".

[0069] The electroless nickel plating bath of the present invention preferably contains hypophosphite as a reducing agent. The crack resistance of the electroless nickel plating film (electroless nickel-phosphorus plating film) formed by containing hypophosphite is further improved. Among hypophosphite, sodium hypophosphite monohydrate is more preferred.

[0070] The concentration of the reducing agent in the electroless nickel plating bath of the present invention is preferably 4–16 g / L. With this concentration of reducing agent, an electroless nickel plating film with excellent crack resistance can be formed at a good deposition rate, while avoiding high costs. More preferably, the concentration of the reducing agent in the plating bath of the present invention is 7–14 g / L.

[0071] 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 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 can be used alone or in combination of two or more.

[0072] In the electroless nickel plating bath of the present invention, the complexing agent preferably contains amino acids (salts). By containing amino acids (salts), it is possible to prevent the plating bath from becoming cloudy.

[0073] Examples of amino acids include glycine, alanine, lysine, glutamine, glutamic acid, asparagine, and aspartic acid.

[0074] Examples of amino acid salts include alkali metal salts such as sodium and potassium; alkaline earth metal salts such as calcium; and ammonium salts.

[0075] In the electroless nickel plating bath of the present invention, the concentration of the complexing agent is preferably 5-50 g / L. With this concentration of complexing agent, the formation of nickel hydroxide and nickel phosphite precipitates in the plating bath can be suppressed while a good precipitation rate is achieved to form an electroless nickel plating film with excellent crack resistance. Since nickel phosphite is a substance that causes crack formation, suppressing the formation of nickel phosphite enables the formation of an electroless nickel-phosphite plating film with even better crack resistance. More preferably, the concentration of the complexing agent in the plating bath of the present invention is 12-45 g / L, and even more preferably 20-40 g / L.

[0076] In the electroless nickel plating bath of the present invention, the crystal structure regulator contains one or more of formic acid (salt), compounds represented by the above general formula (1), and compounds represented by the above general formula (2).

[0077] When n in the above general formula (1) 1 Or n in the above general formula (2) 2 When it is 1, it is used as R 1 R 2 Monovalent hydrocarbon groups can include alkyl, alkenyl, and ynyl groups.

[0078] Furthermore, the monovalent hydrocarbon group can be a straight-chain or branched chain structure, a cyclic structure, or a combination of chain and cyclic structures. The cyclic structure can be an alicyclic structure or an aromatic ring.

[0079] R 1 R 2 The hydrocarbon group preferably has 1 to 5 carbon atoms. More preferably, it has 1 to 3.

[0080] When n in the above general formula (1) 1 Or n in the above general formula (2) 2 When the value is 2 or higher, it is considered as R. 1 R 2 Hydrocarbon groups, for example, can be derived by removing the n-type hydrocarbon group from the aforementioned monovalent hydrocarbon groups. 1 or n 2 The number of hydrogen atoms corresponds to the number of divalent or higher hydrocarbon groups obtained.

[0081] When R in the above general formula (1) 1 R in general formula (2) 2 When a hydrocarbon group has substituents, examples of substituents include halogen atoms such as chlorine and fluorine; hydroxyl groups; carboxyl groups; cyano groups; sulfonic acid groups; phosphoric acid groups; alkoxy groups; -C(=O)-R groups (ketone groups), nitro groups, amino groups, ether-containing groups (-OR groups), amide-containing groups (-NHC(=O)-R groups), ester-containing groups (-COO-R groups), etc. In ketone groups, ether-containing groups, amide-containing groups, and ester-containing groups, R represents a monovalent hydrocarbon group. Examples of monovalent hydrocarbon groups include R in the above general formula (1). 1 Or R in the above general formula (2) 2 The same group as the monovalent hydrocarbon group.

[0082] When R in the above general formula (1) 1 R in general formula (2) 2 When a hydrocarbon group has substituents, it can have only one substituent or it can have two or more substituents.

[0083] In the above general formula (1), n1 Or n in the above general formula (2) 2 The value is 1 or more, preferably 1 to 5. More preferably 1 to 3.

[0084] Examples of metal atoms representing Z in the above general formula (2) include alkali metal atoms such as sodium and potassium.

[0085] Examples of compounds represented by the above general formula (1) include alkyl esters of formic acid such as methyl formate, ethyl formate, isobutyl formate, and pentyl formate; alkyl esters of formic acid with substituents such as cyanomethyl formate; alkenyl esters of formic acid; dicarboxylate, 3-formyloxypropyl formate, and 1,2-propanediol formate; and tricarboxylate, etc.

[0086] Examples of compounds represented by the above general formula (2) include pyruvate, trimethylpyruvate, phenylpyruvate, 2,4-dioxovalerate, 3,4-dihydroxyphenylpyruvate, 3-bromopyruvate, etc.

[0087] In the electroless nickel plating bath of the present invention, the concentration of the crystal structure modifier is preferably 0.5 to 30 g / L. By containing the crystal structure modifier at this concentration, a nickel film with excellent crack resistance can be obtained, in which the measured peak intensity ratio of Ni(111) to Ni(220) in the crystal structure measured by X-ray diffraction is less than 1.0.

[0088] In the electroless nickel plating bath of the present invention, the concentration of the crystal structure modifier is more preferably 3 to 20 g / L, and even more preferably 5 to 10 g / L.

[0089] The electroless nickel plating bath of the present invention may contain carboxylic acid (salt). By containing carboxylic acid (salt), the deposition rate of the electroless nickel plating film can be adjusted.

[0090] Examples of carboxylic acids include adipic acid, oxalic acid, malonic acid, succinic acid, gluconic acid, and citric acid.

[0091] Examples of carboxylates include alkali metal salts such as sodium and potassium; alkaline earth metal salts such as calcium; and ammonium salts.

[0092] When the electroless nickel plating bath of the present invention contains carboxylic acid (salt), the concentration of carboxylic acid (salt) is preferably 1 to 50 g / L. More preferably, it is 3 to 35 g / L, and even more preferably, it is 5 to 20 g / L.

[0093] The electroless nickel plating bath of the present invention may contain a stabilizer. By containing a stabilizer, the decomposition of the plating bath can be prevented.

[0094] Examples of stabilizers include lead compounds such as lead nitrate and lead acetate; cadmium compounds such as cadmium nitrate and cadmium acetate; thallium compounds such as thallium sulfate and thallium nitrate; antimony compounds such as antimony chloride and potassium antimony tartrate; telluric acid and tellurium chloride; chromium compounds such as chromium oxide and chromium sulfate; iron compounds such as ferric sulfate and ferric chloride; manganese compounds such as manganese sulfate and manganese nitrate; bismuth compounds such as bismuth nitrate and bismuth acetate; tin compounds such as tin sulfate and tin chloride; selenium compounds such as selenic acid and selenite; cyanides such as methylcyanide and isopropyl cyanide; and allyl compounds such as allylamine and diallylamine.

[0095] 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 this concentration, a coating can be formed while maintaining the stability of the plating bath. More preferably, it is 0.05 to 50 mg / L, and even more preferably, it is 0.1 to 10 mg / L.

[0096] The electroless nickel plating bath of the present invention may also contain other components besides those described above. Examples of other components include sulfur compounds and surfactants.

[0097] Examples of sulfur compounds include thiosulfate or its salts (e.g., sodium salts), mercaptoacetic acid, thiodiacetic acid, thiourea, and bases of thiocyanate, which are commonly used as sulfur additives in electroless nickel plating.

[0098] As surfactants, various types of surfactants can be used, including nonionic, anionic, cationic, and amphoteric surfactants. Examples include aromatic or aliphatic sulfonic acid alkali metal salts and aromatic or aliphatic carboxylic acid alkali metal salts.

[0099] These can be used individually or in combination of two or more.

[0100] In the electroless nickel plating bath of the present invention, the content of other components besides those mentioned above is preferably 1000 mg / L or less. More preferably, it is 500 mg / L or less, and even more preferably, it is 200 mg / L or less.

[0101] The electroless nickel plating bath of the present invention contains water as a solvent.

[0102] The pH of the electroless nickel plating bath of the present invention is 4 to 8. If the pH is within this range, the plating bath can be kept stable, and uneven appearance of the formed coating can be effectively suppressed. The preferred pH of the plating bath is 5 to 7.

[0103] The pH of the plating bath can be adjusted by adding acid or alkali to the plating bath.

[0104] <Method for manufacturing electroless nickel plating film>

[0105] The present invention discloses a method for manufacturing an electroless nickel plating film, comprising the step of contacting the object to be plated with an electroless nickel plating bath to form an electroless nickel plating film.

[0106] The electroless nickel plating bath contains: a water-soluble nickel compound, a reducing agent, a complexing agent, and one or more compounds selected from formic acid (salt), compounds represented by the following general formula (1), and compounds represented by the following general formula (2) as crystal structure regulators.

[0107] The manufacturing method includes a step of forming a coating at a deposition rate of less than 10 μm / h.

[0108]

Transformation 3

[0109]

[0110] (In equation (1), R) 1 Indicates a hydrocarbon group with or without substituents. 1 (Represents numbers greater than 1.)

[0111]

Chemistry 4

[0112]

[0113] (In equation (2), R) 2 Indicates a hydrocarbon group with or without substituents. Z represents a hydrogen atom or a metal atom. n 2 (Represents numbers greater than 1.)

[0114] The electroless nickel plating bath of the present invention, and the coating formed at a low deposition rate of less than 10 μm / h, can form an electroless nickel plating film with excellent crack resistance, which can suppress cracking even in heat treatment above 400°C or in thermal cycling tests with temperatures varying between 250°C and -50°C.

[0115] In the method for manufacturing the electroless nickel plating film of the present invention, the plating deposition rate only needs to be less than 10 μm / h, but considering the need 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. More preferably, it is 1 to 6 μm / h.

[0116] The concentration of reducing agent in an electroless nickel plating bath affects the deposition rate; the higher the concentration, the faster the deposition rate tends to be.

[0117] Furthermore, the deposition rate of electroless nickel plating tends to increase by increasing the concentration of reducing agent, temperature, nickel concentration, or decreasing the concentration of complexing agent.

[0118] In the method for manufacturing the electroless nickel plating film of the present invention, the temperature for the film-forming process is not particularly limited as long as the film can be formed, but is preferably 30 to 100°C. By performing the film-forming process at this temperature, a film with excellent heat resistance can be formed with good production efficiency while maintaining the stability of the plating bath. The temperature for the film-forming process is more preferably 70 to 100°C, and even more preferably 80 to 95°C.

[0119] In the method for manufacturing an electroless nickel plating film of the present invention, the time for forming the plating film can be appropriately adjusted according to the size of Cu, Al, Fe and their alloys, resin, glass substrate, and the thickness of the formed plating film.

[0120] The time for forming the coating process can be determined for example, by immersing the substrate in the coating bath for a specific time in advance, confirming the relationship between the coating time and the film thickness based on the resulting coating thickness, and then determining the coating thickness according to the required coating thickness.

[0121] The method for manufacturing the electroless nickel plating film of the present invention may include steps other than the film formation step. Examples of such steps include pretreatment steps. In the pretreatment step, it is preferable to select an appropriate treatment from the following processes: cleaning, pickling, etching, activation, zinc plating, demutation, etc., depending on the type of substrate.

[0122] In the method for manufacturing the electroless nickel plating film of the present invention, there are no particular restrictions on the substrate for forming the film, and Cu, Al, Fe and their alloys, resin, glass, etc. can be used.

[0123] Furthermore, the electroless nickel plating film manufactured by the method of the present invention can be used as a bonding portion of a semiconductor substrate. In this case, examples of semiconductor substrates include DBC substrates, DBA substrates, and AMB substrates. Here, DBC stands for Direct Bonded Copper, DBA for Direct Bonded Aluminum, and AMB for Active Metal Brazing.

[0124] The processing conditions and concentration settings described above are not limited to those conditions and can be appropriately changed according to the thickness of the formed film, etc.

[0125] Furthermore, after forming the electroless nickel plating film of the present invention on the substrate, it is possible to further form electroless gold plating films, electroless palladium plating films, electroless silver plating films, and other metal plating films. That is, after forming the electroless nickel plating film on the substrate using the manufacturing method of the present invention, further steps can be performed to form electroless gold plating films, electroless palladium plating films, electroless silver plating films, and other metal plating films.

[0126] Thus, as long as an electroless nickel plating film is formed by the electroless nickel plating film manufacturing method of the present invention, even if subsequent processes are carried out to form other metal plating films such as electroless gold plating film, electroless palladium plating film, and electroless silver plating film, it still falls within the technical scope of the electroless nickel plating film manufacturing method of the present invention.

[0127] The electroless nickel plating film of the present invention is a nickel film that can suppress cracking even under large temperature changes or high temperature environments and has excellent crack resistance. It is most suitable for bonding power semiconductors whose operating temperature becomes high.

[0128]

Example

[0129] The present invention will be specifically described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0130] The various measurements were performed as follows.

[0131] <pH Measurement>

[0132] The prepared plating solution was measured at room temperature (25°C) using a pH meter (HM-41X manufactured by Toa DKK Corporation).

[0133] <Crack Resistance Evaluation>

[0134] (Extrusion test using an Ericsson cupping tester)

[0135] The electroless nickel-phosphorus coatings formed on iron plates in the following examples and comparative examples were heat-treated at a predetermined temperature for 30 minutes. The heat-treated electroless nickel-phosphorus coatings were then pressed out to a thickness of 0.4 mm or 0.5 mm using an Ericsson cupping tester. The condition of the cracks generated on the convex side of the electroless nickel-phosphorus coating after pressing was confirmed using a digital microscope (Keyence VHX-7000) at 80x magnification.

[0136] <Precipitation Rate Measurement>

[0137] The film thickness is calculated based on the weight difference and density before and after coating, and the deposition rate (μm / hr) is determined.

[0138]

[0139] The phosphorus content in the electroless nickel-phosphorus coating was determined using a wavelength dispersive X-ray fluorescence spectrometer (Rigaku ZSX Primus IV).

[0140] <Coating Hardness>

[0141] (Vickers hardness test)

[0142] The electroless nickel-phosphorus coating was heat-treated at 400°C for 30 minutes. The Vickers hardness of the electroless nickel-phosphorus coating surface before and after heat treatment was measured using a micro Vickers hardness tester (Mitutoyo HM-200B) (load 0.1Kg) at room temperature (25°C).

[0143] <XRD Measurement>

[0144] (Analysis performed by X-ray diffraction (XRD analysis))

[0145] The electroless nickel-phosphorus coating formed on the iron plate as described above was analyzed using an XRD measuring device (Smart Lab manufactured by Rigaku Corporation).

[0146] Example 1-1

[0147] Using the electroless nickel plating bath prepared as described in Table 1, and with an iron plate as the substrate, the substrate is immersed in the electroless nickel plating bath at a temperature of 90°C for a specified time to form an electroless nickel plating film with a thickness of 3–5 μm. It should be noted that the concentrations of water-soluble Ni compounds listed in Table 1 refer to the concentration of nickel sulfate hexahydrate and the concentration of nickel contained in the nickel sulfate hexahydrate. Tables 2–5 follow the same principle.

[0148] The precipitation rate was measured, and the crack resistance, phosphorus content, and hardness of the obtained electroless nickel-phosphorus coating were evaluated. Furthermore, the peak intensity ratio of Ni(111) to Ni(220) in the obtained electroless nickel-phosphorus coating, Ni(111) / Ni(220), was confirmed. The results are shown in Table 1. The XRD results of the electroless nickel-phosphorus coating obtained in Examples 1-1 are as follows: Figure 3 As shown.

[0149] Examples 1-2 to 1-10, Comparative Example 1-1

[0150] Except for changing the composition of the plating bath as shown in Table 1, electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1. The deposition rate was measured in the same manner as in Example 1-1, and the resulting electroless nickel-phosphorus coating was evaluated for crack resistance, P content, and hardness. Furthermore, the measured peak intensity ratio of Ni(111) to Ni(220) in the obtained electroless nickel-phosphorus coating, Ni(111) / Ni(220), was confirmed. The results are shown in Table 1. In addition, XRD measurements were performed on the electroless nickel-phosphorus coating obtained in Comparative Example 1-1. The results are as follows: Figure 4 As shown.

[0151] Table 1

[0152]

[0153] In the examples and comparative examples, crack resistance was evaluated under harsh heat treatment conditions above 350°C. No cracks were detected and the cracks were detected and the crack resistance was ...

[0154] The results in Table 1 confirm that by using a plating bath containing formic acid or formate as a crystal structure modifier, an electroless nickel-phosphorus coating with excellent crack resistance can be obtained even under heat treatment at 350°C.

[0155] Furthermore, it was confirmed that the ratio of the measured peak intensity of Ni(111) to Ni(220) of the coating obtained by using a plating bath containing formic acid or formate as a crystal structure modifier was less than 1.0; while the ratio of Ni(111) to Ni(220) of the coating obtained by using a plating bath without formic acid or formate was greater than 1.0.

[0156] Examples 2-1 to 2-7 (Confirming the effect of precipitation rate)

[0157] Using an iron plate as the substrate, electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1, except that the composition of the plating bath was set as shown in Table 2. The crack resistance and phosphorus content of the obtained electroless nickel-phosphorus coating were evaluated. Furthermore, the measured peak intensity ratio of Ni(111) to Ni(220) in the obtained electroless nickel-phosphorus coating, Ni(111) / Ni(220), was confirmed. The results are shown in Table 2.

[0158] Table 2

[0159]

[0160] Examples 2-1 to 2-5 illustrate how the deposition rate was altered by adjusting the concentration of the reducing agent (sodium hypophosphite monohydrate). It was confirmed that within a deposition rate up to 9.5 μm / hr, a coating exhibiting excellent crack resistance even under heat treatment at 350°C could be obtained; and it was confirmed that by further reducing the deposition rate, a coating exhibiting excellent crack resistance even under higher heat treatment temperatures could be obtained.

[0161] Furthermore, Examples 2-6, which maintained the same reducing agent concentration as Examples 2-4 but altered the precipitation rate by adjusting the concentrations of other components, were compared with Examples 2-4. Examples 2-6, with a slower precipitation rate, yielded a coating with excellent crack resistance even under higher temperature heat treatment. Further, Examples 2-7, which maintained the same reducing agent concentration as Example 2-1 but set the carboxylic acid addition to 0, were compared with Example 2-1. Examples 2-1, with a slower precipitation rate, yielded a coating with excellent crack resistance even under higher temperature heat treatment. These comparisons confirm that the precipitation rate has a significant impact on the crack resistance of the coating.

[0162] In any of the examples 2-1 to 2-7, it was confirmed that the measured peak intensity ratio of Ni(111) to Ni(220) of the obtained coating was less than 1.0.

[0163] Examples 3-1 to 3-6, Comparative Examples 3-1 to 3-3 (pH Changes)

[0164] Except for changing the composition of the plating bath as shown in Table 3, electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1. The deposition rate was measured in the same manner as in Example 1-1, and the crack resistance and phosphorus content of the obtained electroless nickel-phosphorus coating were evaluated. In addition, the measured peak intensity ratio of Ni(111) to Ni(220) of the obtained electroless nickel-phosphorus coating was confirmed as Ni(111) / Ni(220). The results are shown in Table 3.

[0165] Table 3

[0166]

[0167] 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. According to Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-3, in order to obtain a coating with excellent crack resistance even under high-temperature heat treatment at 350°C, the pH of the plating bath needs to be 4 to 8.

[0168] For the coatings of Examples 3-1 to 3-6 using a plating bath with a pH of 4 to 8, the Ni(111) / Ni(220) ratio is less than 1.0; while for the coatings of Comparative Examples 3-1 to 3-3 using a plating bath with a pH of less than 4 or greater than 8, either no coating is formed or the Ni(111) / Ni(220) ratio is greater than 1.0.

[0169] Examples 4-1 to 4-3 (Changes in the complexing agent)

[0170] Except for changing the composition of the plating bath as shown in Table 4, electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1. The deposition rate was measured as in Example 1-1, and the crack resistance and phosphorus content of the obtained electroless nickel-phosphorus coating were evaluated. Furthermore, the measured peak intensity ratio of Ni(111) to Ni(220) in the obtained electroless nickel-phosphorus coating, Ni(111) / Ni(220), was confirmed. The results are shown in Table 4.

[0171] Table 4

[0172]

[0173] Examples 4-1 to 4-3 are examples of changing the complexing agent in the plating bath. According to Examples 4-1 to 4-3, regardless of the type of complexing agent, a coating with excellent crack resistance can be obtained even under high-temperature heat treatment at 350°C.

[0174] The Ni(111) / Ni(220) ratios of the coatings in Examples 4-1 to 4-3 are all less than 1.0.

[0175] Examples 5-1 to 5-5, Comparative Examples 5-1 to 5-9 (Changes in crystal structure modifiers)

[0176] Except for changing the composition of the plating bath as shown in Table 5, electroless nickel-phosphorus plating was performed in the same manner as in Example 1-1. The deposition rate was measured in the same manner as in Example 1-1, and the crack resistance and phosphorus content of the obtained electroless nickel-phosphorus coating were evaluated. In addition, the measured peak intensity ratio of Ni(111) to Ni(220) of the obtained electroless nickel-phosphorus coating was confirmed as Ni(111) / Ni(220). The results are shown in Table 5.

[0177] Table 5

[0178]

[0179] Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-9 are examples of changing the crystal structure modifier in the plating bath. In Examples 5-1 to 5-5, which used any one of formic acid (salt), compounds represented by general formula (1), and compounds represented by general formula (2) as crystal structure modifiers, it was confirmed that a coating with excellent crack resistance could be obtained even under high-temperature heat treatment at 350°C. On the other hand, in Comparative Examples 5-1 to 5-9, which used compounds not selected from formic acid (salt), compounds represented by general formula (1), and compounds represented by general formula (2), the formed coatings cracked under high-temperature heat treatment at 350°C (Comparative Examples 5-1 to 5-4, 5-7 to 5-9), or the plating bath decomposed and no coating was formed (Comparative Examples 5-5, 5-6).

[0180] According to Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-9, in order to obtain a coating with excellent crack resistance even under high-temperature heat treatment at 350°C, it is necessary to use any one of formic acid (salt), compound represented by general formula (1), or compound represented by general formula (2) as a crystal structure modifier for the coating bath.

[0181] For the coatings of Examples 5-1 to 5-5, which use any one of formic acid (salt), compound represented by general formula (1), or compound represented by general formula (2) as crystal structure modifiers for the plating bath, the Ni(111) / Ni(220) ratio is less than 1.0; however, in Comparative Examples 5-1 to 5-9, which use compounds other than these as crystal structure modifiers for the plating bath, no coating is formed, or even if a coating is formed, the Ni(111) / Ni(220) ratio is greater than 1.0.

[0182] As shown in Tables 1-5, by using the plating bath of the present invention and forming a coating at a deposition rate of less than 10 μm / h, a coating with excellent crack resistance under high temperature conditions can be obtained. The coating of the present invention has a characteristic peak with a Ni(111) / Ni(220) intensity ratio of less than 1.0 in X-ray diffraction analysis.

[0183] The method for manufacturing electroless nickel plating films using the plating bath of the present invention is very useful for applications requiring high heat resistance, such as junctions of power semiconductors.

Claims

1. An electroless nickel plating film, characterized in that, The ratio of the peak intensity of Ni(111) to Ni(220) in the electroless nickel plating film analyzed by X-ray diffraction is less than 1.

0.

2. An electroless nickel plating bath for forming the electroless nickel plating film of claim 1, characterized in that, The electroless nickel plating bath contains: a water-soluble nickel compound, a reducing agent, a complexing agent, and one or more compounds selected from formic acid or formate, compounds represented by the following general formula (1), and compounds represented by the following general formula (2) as crystal structure regulators. The pH of the electroless nickel plating bath is 4–8; ， In equation (1), R 1 Indicates a hydrocarbon group with or without substituents, n 1 Represents numbers greater than or equal to 1; ， In equation (2), R 2 Indicates a hydrocarbon group with or without substituents, Z represents a hydrogen atom or a metal atom, n 2 It represents numbers greater than or equal to 1.

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

4. The electroless nickel plating bath according to claim 2, wherein, The reducing agent comprises hypophosphoric acid or hypophosphite.

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

6. The electroless nickel plating bath according to claim 2, wherein, The complexing agent contains amino acids.

7. The electroless nickel plating bath according to claim 2, wherein, The concentration of the complexing agent is 5–50 g / L.

8. A method for manufacturing an electroless nickel plating film, comprising a step of contacting the object to be plated with an electroless nickel plating bath to form an electroless nickel plating film, characterized in that, The electroless nickel plating bath contains: a water-soluble nickel compound, a reducing agent, a complexing agent, and one or more compounds selected from formic acid or formate, compounds represented by the following general formula (1), and compounds represented by the following general formula (2) as crystal structure regulators. The manufacturing method includes a step of forming a coating at a deposition rate of less than 10 μm / h; ， In equation (1), R 1 Indicates a hydrocarbon group with or without substituents, n 1 Represents numbers greater than or equal to 1; ， In equation (2), R 2 Indicates a hydrocarbon group with or without substituents, Z represents a hydrogen atom or a metal atom, n 2 It represents numbers greater than or equal to 1.

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