Ni-W alloy plating film and method for manufacturing the same.

Abstract

The objective is to provide a Ni-W alloy plating film with excellent corrosion resistance and a method for manufacturing the same. [Solution] A method for producing a Ni-W alloy plated film, comprising using a plating solution containing nickel salt, tungsten salt, and citric acid components, setting the sodium concentration in the plating solution to 1.7 mol / L or less during initial adjustment, and maintaining the sodium concentration in the plating solution to 1.7 mol / L or less after the start of operation.

Description

[Technical Field]

[0001] This disclosure relates to Ni-W alloy plating films and methods for producing the same. [Background technology]

[0002] Semiconductor chips are joined to external electrodes using wire bonding or solder bumps. The connection terminals have a nickel or nickel alloy plating layer formed as an underlayer on Al or Cu electrodes, and a plating layer of Pd or Au formed on top of that. For example, Patent Document 1 discloses a circuit board having a nickel or nickel alloy layer, a palladium layer, and optionally a gold or gold alloy layer. Patent Document 2 discloses an article having a copper substrate, a first layer containing Ni and one or both of W and Mo, and a second layer containing one or more metals from Au, Ru, Os, Rh, Ir, Pd, Pt, and Ag.

[0003] Furthermore, connectors and electrical contacts use metals with high electrical conductivity, such as gold, silver, and copper. However, since these are soft materials, their surface is plated with hard materials such as nickel or cobalt to improve wear resistance. For example, Patent Document 3 discloses a plating layer in which TiB2 or ZrB2 particles are dispersed in an alloy matrix of Au-Ni, Au-Co, or Au-In-Co on an alloy plating layer of Ni-W, Ni-Mo, Co-W, or Co-Mo. It is stated that by having such a layer structure, the switching life of electrical contacts such as relays can be improved. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2008-527175 [Patent Document 2] Japanese Patent Publication No. 2018-138700 [Patent Document 3] Japanese Patent Application Publication No. 52-58023 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Ni-W alloy plating films, which offer excellent wear resistance, corrosion resistance, and heat resistance, are sometimes used for connection terminals and connectors. However, depending on the plating conditions, the corrosion resistance of Ni-W alloy plating films may decrease. In view of these circumstances, this disclosure aims to provide a Ni-W alloy plating film with excellent corrosion resistance and a method for manufacturing the same. [Means for solving the problem]

[0006] The gist of this disclosure is as follows: [1] A method for producing a Ni-W alloy plated film, comprising using a plating solution containing a nickel salt, a tungsten salt, and a citric acid component, wherein the sodium concentration in the plating solution during initial preparation is 1.7 mol / L or less, and the sodium concentration in the plating solution after the start of operation is 1.7 mol / L or less. [2] A method for producing a Ni-W alloy plating film according to [1], wherein the integrated current value in the plating solution is x (Ah / L) and the sodium concentration is y (mol / L), and the following equation (1) or (2) is satisfied. (1) y≦0.060x+0.4 (0≦x≦21.6) (2) y ≤ 1.7 (21.6 <x) [3] A method for producing a Ni-W alloy plating film according to [1], wherein the integrated current value in the plating solution is x (Ah / L) and the sodium concentration is y (mol / L), and the following equation (3) or (4) is satisfied. (3) y≦0.030x+0.4 (0≦x≦43.3) (4) y≦1.7 (43.3 <x) [4] A method for producing a Ni-W alloy plating film according to [1], wherein the integrated current value in the plating solution is x (Ah / L) and the sodium concentration is y (mol / L), and the following equation (5) or (6) is satisfied. (5) y≦0.014x+0.4 (0≦x≦92.8) (6) y≦1.7 (92.8 <x) [5] A method for producing a Ni-W alloy plating film according to any one of [1] to [4], further comprising a formic acid component. [6] A method for producing a Ni-W alloy plating film according to any one of [1] to [5], further comprising a surfactant. [7] A Ni-W alloy plating film manufactured by any one of the manufacturing methods described in [1] to [6], wherein the corrosion area ratio is less than 5% in a nitric acid aeration test (left in a nitric acid atmosphere for 2 hours). [Effects of the Invention]

[0007] According to this disclosure, a method for manufacturing a Ni-W alloy plating film with excellent corrosion resistance can be provided. [Modes for carrying out the invention]

[0008] Ni-W alloy plating films are produced by immersing a substrate (object to be plated) in a Ni-W alloy plating solution and performing electroplating under predetermined conditions. In this case, the plating solution is not used only once, but in some cases, plating films are produced continuously for tens of thousands or even hundreds of thousands of times or more. Therefore, it is important to maintain the performance of the plating solution even when the cumulative current value (Ah / L) is increased. Specifically, a control range is set for each component of the plating solution, and electroplating can be performed by adjusting the concentration of each component of the plating solution so that the concentration does not exceed the upper / lower limit. For example, if the plating solution is analyzed every 2-3 Ah / L of cumulative current, and the concentration has decreased, each component can be replenished to bring it back within the control range.

[0009] When continuously producing plated films using the same plating bath, as described above, the necessary components of the plating solution are replenished according to the accumulated current value. However, this resulted in a significant decrease in the corrosion resistance of the Ni-W alloy plated film. Through diligent research, it was discovered that sodium ions contained in tungsten, citric acid, and formic acid components accumulate in the Ni-W alloy plating solution, affecting the decrease in corrosion resistance. The mechanism by which sodium ions affect the corrosion resistance of the plated film is not fully understood, but it is presumed that they are related to the hydration structure, including water molecules around the sodium ions, and somehow influence the inductive electrodeposition mechanism, such as that of Ni-W alloy plating.

[0010] In view of the above findings, the method for producing a Ni-W alloy plating film according to the embodiment of this disclosure uses a plating solution containing a nickel salt, a tungsten salt, and a citric acid component, and the sodium concentration in the plating solution during initial adjustment is 1.7 mol / L or less, and the sodium concentration in the plating solution after the start of operation is 1.7 mol / L or less. Here, initial adjustment refers to the time when the plating bath is prepared, that is, when the cumulative current value is 0 Ah / L. After the start of operation refers to the period from when the cumulative current value is 0 Ah / L, using the same plating tank, until the production of the Ni-W alloy plating film is stopped. In this embodiment, there is no upper limit on the cumulative current value, but it can be used well up to at least 100 Ah / L. Furthermore, it can be used up to 130 Ah / L, and is usable up to 150 Ah / L.

[0011] During initial adjustment and after the start of operation, when the sodium concentration exceeds 1.7 mol / L, the corrosion resistance of the produced Ni-W alloy plating film significantly decreases. Therefore, analyze the concentration of each component of the Ni-W alloy plating solution for each predetermined integrated current value, and replenish each component so that the sodium concentration does not exceed 1.7 mol / L. In particular, when sodium ions are contained in the citric acid component or the formic acid component, they gradually accumulate and the sodium concentration increases. Therefore, it is necessary to strictly control the replenishment timing and amount. There is no particular limitation on the timing for analyzing each component of the Ni-W alloy plating solution. For example, analysis and replenishment can be performed every 2 - 3 Ah / L of the integrated current value. Since the concentration of each component can be estimated to some extent from the plating conditions, the analysis period can be further widened (the number of analyses can be further reduced).<AAAAAAA><BBBBBBB><CCCCCCC>In an embodiment of the present disclosure, it is preferable that the sodium concentration in the plating solution satisfies the following formula (1) or (2) when the integrated current value is x (Ah / L) and the sodium concentration is y (mol / L).<DDDDDDD>(1) y ≦ 0.060x + 0.4 (0 ≦ x ≦ 21.6)<EEEEEEE>(2) y ≦ 1.7 (21.6 < x)<FFFFFFFF>By analyzing the components of the plating solution for each predetermined integrated current value and replenishing them so that the sodium concentration satisfies the above management range, it becomes possible to improve the corrosion resistance of the Ni-W alloy plating film.<GGGGGGG><HHHHHHH><IIIIIII>More preferably, it is to satisfy the following formula (3) or (4).<JJJJJJJ>(3) y ≦ 0.030x + 0.4 (0 ≦ x ≦ 43.3)<KKKKKKK>(4) y ≦ 1.7 (43.3 < x)<LLLLLLL>Even more preferably, it is to satisfy the following formula (5) or (6).<MMMMMMM>(5) y ≦ 0.014x + 0.4 (0 ≦ x ≦ 92.8)<NNNNNNN>(6) y ≦ 1.7 (92.8 < x)<OOOOOOO><PPPPPPP><QQQQQQQ>(Regarding the plating solution)<RRRRRRR>The plating solution using the manufacturing method of this disclosure contains a nickel salt, a tungsten salt, a citric acid component, and a formic acid component. As the nickel salt, one or more of the following can be used: nickel sulfate hexahydrate, nickel formate dihydrate, nickel acetate tetrahydrate, nickel sulfamate tetrahydrate, and nickel chloride hexahydrate. The nickel component may also be recycled. The control range for nickel concentration is preferably 4.9 to 7.0 g / L from the viewpoint of the W eutectoid rate in the Ni-W alloy plating film. Therefore, the nickel concentration is analyzed and replenished at predetermined cumulative current values ​​so as not to deviate from this control range. Note that since the above-mentioned nickel salts do not contain sodium ions, the addition of nickel salts itself does not contribute to an increase in sodium concentration.

[0015] The tungsten salt can be one or more of the following: sodium tungstate dihydrate, potassium tungstate, ammonium tungstate-para-pentahydrate, tungstic acid, or tungsten oxide. Furthermore, the tungsten component may be recycled. The control range for tungsten concentration is preferably 29.4 to 40.4 g / L from the viewpoint of the W eutectoid rate in the Ni-W alloy plating film. Therefore, to avoid exceeding this control range, the tungsten concentration should be analyzed and replenished at predetermined cumulative current values. At this time, since the tungsten salt contains sodium ions, care must be taken to ensure that the sodium ion concentration does not exceed a predetermined level during analysis and replenishment.

[0016] The citric acid components include triammonium citrate, diammonium hydrogen citrate, tripotassium citrate monohydrate, dipotassium hydrogen citrate, trisodium citrate monohydrate, disodium hydrogen citrate, and citric acid monohydrate. Citric acid is nickel Citric acid has the effect of stabilizing tungsten in the plating bath, and it is preferable to control the citric acid concentration within a range of 48.4 to 72.6 g / L. Therefore, in order to avoid exceeding this control range, the citric acid concentration is analyzed and replenished at predetermined cumulative current values. It is preferable to use citric acid that does not contain sodium ions, and in particular, it is preferable to use triammonium citrate, tripotassium citrate monohydrate, and citric acid monohydrate. Furthermore, the inclusion of these three types makes it easier to adjust the ammonia concentration and to adjust the initial pH of the plating solution.

[0017] It is preferable that the plating solution also contains a formic acid component. Ammonium formate, potassium formate, and sodium formate can be used as the formic acid component. Formic acid acts as a sacrificial oxidizing agent, suppressing the decomposition of the citric acid component during electrolysis. The control range for formic acid concentration is preferably 0 to 46.0 g / L. Therefore, to prevent deviation from this control range, the formic acid concentration is analyzed and replenished at predetermined cumulative current values. It is preferable to use formic acid that does not contain sodium ions, and in particular, potassium formate is preferred.

[0018] Preferably, the plating solution further contains a surfactant. As the surfactant, at least one selected from the group consisting of cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants can be used. It is believed that using a surfactant significantly reduces surface tension, making it easier for hydrogen gas generated from the cathode to escape, thereby preventing defects called pits and pinholes, and improving corrosion resistance. Particularly preferable is the use of an amphoteric surfactant.

[0019] As cationic surfactants, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, N-methylbishydroxyethylamine fatty acid esters, and hydrochloride salts can be used. As anionic surfactants, higher fatty acid salts, α-sulfo fatty acid methyl ester salts, linear alkylbenzene sulfonates, alkyl sulfate ester salts, alkyl ether sulfate ester salts, monoalkyl phosphate ester salts, α-olefin sulfonates, and alkane sulfonates can be used. In addition, as amphoteric surfactants, alkylamino fatty acid salts, alkyl betaines, and alkylamine oxides can be used. As nonionic surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, alkyl glycosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and fatty acid alkanolamides can be used.

[0020] (Conditions for electroplating) An example of the conditions for electroplating is as follows: Current density (Dk): 5.0~25A / dm 2 (Preferably 7.0~22A / dm 2 ) pH: 6.0-9.0 (preferably 6.5-8.5) Bath temperature: 50~70℃ In addition to DC plating, pulse plating and PR plating may also be used.

[0021] (Ni-W alloy plating film) The Ni-W alloy plating film according to the embodiments of this disclosure is characterized in that no corrosion occurs in a nitric acid aeration test performed under the following conditions. <Nitric Acid Aeration Test> Place 150 mL of 70% nitric acid in a desiccator and set it in a bathtub maintained at 25°C. Next, after letting it stand for 30 minutes after adding the nitric acid, place the evaluation sample into the desiccator and add the nitric acid. The sample is left in the atmosphere for 2 hours. After that, the evaluation sample is heated on a hot plate at 120°C for 10 minutes, and the presence or absence of corrosion is checked with a digital microscope. The corrosion area relative to the evaluation area is observed with a digital microscope, and the conditions for brightness, hue, and saturation are set as follows. If any one of conditions 1 to 12 is met, it is determined that corrosion has occurred, and the corrosion area percentage (%) is calculated. If the corrosion area percentage is less than 5%, it is determined that no corrosion has occurred.

[0022] [Table 1]

[0023] In a plating solution, the W eutectoid rate can be controlled by adjusting the Ni and W concentrations. Increasing the W concentration can increase the W eutectoid rate, but since the W eutectoid rate saturates at a certain concentration, adjustments such as lowering the Ni concentration become necessary. Conversely, increasing the Ni concentration or decreasing the W concentration can reduce the W eutectoid rate. Increasing the current density tends to gradually increase the W eutectoid rate.

[0024] In this embodiment, the Ni-W alloy plating film preferably has a W (tungsten) eutectoid rate (average value) of 40 wt% or more. When W reaches 31 wt% or more of its solid solubility limit at room temperature, it exists as a supersaturated solid solution, forming a mixed crystal film of crystalline and amorphous materials, which relieves the internal stress of the plating film. On the other hand, as the W eutectoid rate increases, the volume ratio of amorphous material increases, and the internal stress rises. Thus, the W eutectoid rate correlates with the internal stress of the plating film, and if the eutectoid rate is 55 wt% or less, the internal stress can be kept low, and the occurrence of cracks in the Ni-W alloy film can be suppressed. Preferably, it is 41 wt% or more, 42 wt% or more, 53 wt% or less, and 52 wt% or less.

[0025] (Laminated structure) In embodiments of this disclosure, the laminate may comprise a first layer containing a Ni-W alloy plating film on a copper substrate, and a second layer containing one or more metals from Au, Pd, Ag, Pt, Ru, and Rh on the first layer. Alternatively, a Ni film may be included between the copper substrate and the first layer, or between the first layer and the second layer.

[0026] In the laminate of this embodiment, it is preferable that the thickness of the Ni-W alloy plating film be 1.0 μm or more. If the film thickness is less than 1.0 μm, it may be difficult to ensure corrosion resistance depending on the layer structure of the laminate. Although not shown in the examples, according to this embodiment, a film thickness of up to 100 μm can be achieved without crack formation.

[0027] There are no particular restrictions on the thickness of the second layer, but it can be 0.05 μm or more, 0.1 μm or more, or 1.0 μm or more. It can also be 5.0 μm or less, 3.0 μm or less, 1.0 μm or less, 0.5 μm or less, or 0.25 μm or less. If the film thickness is too thin, pinholes may occur. On the other hand, if the film thickness is too thick, cracks may occur, and since it is a precious metal, the cost will be high. From the viewpoint of corrosion resistance, the Ni film is preferably 1.0 μm or more, and from the viewpoint of crack prevention, it is preferably 5.0 μm or less. [Examples]

[0028] Next, examples and comparative examples of the present invention will be described. Note that the following examples are representative examples, and the present invention is not limited to these examples; it should be interpreted within the scope of the technical concept described in the specification.

[0029] The various physical properties of the Ni-W alloy plating solution and the Ni-W alloy plating film in this example and comparative example were evaluated as follows. <Analysis of sodium concentration> The sodium concentration in the plating solution was analyzed using a capillary electrophoresis apparatus (Agilent 7100CE). In addition, the concentrations of citric acid and formic acid were also analyzed using the same apparatus. Moreover, the concentrations of nickel and tungsten in the plating solution were analyzed using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry).

[0030] <Measurement of W eutectoid ratio> The W eutectoid ratio in the plating film was measured by the fundamental parameter method (FP method) using a fluorescence X-ray apparatus (FT160h manufactured by Hitachi High-Tech Science Corporation). In the measurement by the FP method, when the base was copper, since the Kα line of copper and the Kβ line of nickel interfered, nickel used the Kα line. Also, since the Kα line of copper and the Lα line of tungsten interfered, tungsten used the Lβ line or the Lγ line. The W eutectoid ratio was measured at four locations and the average value was obtained.

[0031] <Measurement of film thickness> The fluorescence X-ray intensity of each metal component was obtained using a fluorescence X-ray measurement apparatus (FT160h manufactured by Hitachi High-Tech Science Corporation), and the film thickness was converted from the results. The film thickness was measured at four locations and the average value was obtained.

[0032] <Nitric acid fuming test> 150 mL of 70% nitric acid was placed in a desiccator and set in a bath maintained at a water temperature of 25°C. Next, after leaving it for 30 minutes after adding the nitric acid, the evaluation sample was placed in the desiccator and left for 2 hours in a nitric acid atmosphere. Then, the evaluation sample was heated on a hot plate at 120°C for 10 minutes, and the presence or absence of corrosion was confirmed using a digital microscope. The corrosion area with respect to the evaluation area was observed using a digital microscope, the conditions of lightness, hue, and chroma were set as described in Table 1, and the corrosion area ratio (%) was calculated.

[0033] <Sample preparation and initial plating solution> A copper alloy plate (C5210 material) was electro-degreased (DC power supply device, liquid temperature: 60°C, current density: 20 A / dm 2The sample substrate (plating area: 0.055 dm²) was then immersed for 60 seconds. After that, fluoride etching was performed (50°C, 30 seconds), followed by washing with pure water. 2 A solution was prepared. Next, the initial plating solution (bath volume 1L) shown below was prepared. Nickel(II) sulfate hexahydrate: 26.3g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Tripotassium citrate monohydrate: 4.9 g / L Potassium formate: 42.1 g / L

[0034] (Example 1-1) The sample substrate was plated with a Ni-W alloy using an initial plating solution (sodium concentration of 0.4 mol / L) under the following conditions. Current density: 12A / dm 2 Current value: 0.66A Plating time: 2.3 minutes The cumulative current value is 0.66 × {2.3 / 60} / 1 = 0.03 Ah / L. After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. The results showed a W eutectoid rate of 45.1 wt%, a film thickness of 2.7 μm, and a corrosion area ratio of 0%. These results are shown in Table 2.

[0035] [Table 2]

[0036] (Examples 1-2) Using the initial plating solution from Example 1-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 0.4 mol / L) at 625 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 625 minutes Cumulative current value: 4.8 × {625 / 60} / 1 = 50Ah / L However, until the plating time reached 625 minutes, a so-called "sacrificial plating" was performed, in which the sample substrate was subjected to a simulated Ni-W alloy plating treatment every 2 Ah / L. Normal plating processes involve repeated plating with the same plating solution, and Examples 1-2 demonstrate that corrosion resistance is maintained even under repeated plating conditions. To replenish the various components consumed during the sacrificial plating, the solutions were replenished so that the concentrations of each component remained within the control ranges shown below. Ni concentration: 4.9~7.0g / L W concentration: 29.4~40.4g / L Citric acid concentration: 48.4~72.6 g / L Formic acid concentration: 0-46.0 g / L Furthermore, the cumulative replenishment amount at the 50Ah / L mark is as follows: Nickel(II) sulfate hexahydrate: 100.3g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 24.0 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Tripotassium citrate monohydrate: 46.3 g / L Potassium formate: 111.6 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 44.3 wt%, the film thickness was 2.7 μm, and the corrosion area ratio was 0.1%.

[0037] (Example 2-1) The sodium concentration was adjusted by adding 42.6 g / L of sodium sulfate to the initial plating solution used in Example 1-1. Using this plating solution (sodium concentration of 1.0 mol / L), the sample substrate was subjected to Ni-W alloy plating under the same plating conditions as in Example 1-1. After the plating treatment, the sample substrate was taken out, and as a result of calculating the W eutectoid ratio, film thickness, and corrosion area ratio, as shown in Table 2, the W eutectoid ratio was 42.8 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 0.2%.

[0038] (Example 2-2) Using the plating solution used in Example 2-1, at the plating solution at the 25-minute plating time (sodium concentration was 1.0 mol / L), the sample substrate was subjected to Ni-W alloy plating treatment under the following conditions. Plating area: 0.4 dm 2 Current density: 12 A / dm 2 Current value: 4.8 A Plating time: 2,5 minutes Integrated current value: 4.8×{25 / 60} / 1 = 2 Ah / L Similar to Example 1-2, until the plating time reached 25 minutes, Ni-W alloy plating treatment (waste plating) was pseudo-performed on the sample substrate every 2 Ah / L. To supplement various components consumed in the waste plating, replenishment was carried out so that the concentrations of various components were within the management range, similar to the management range shown in Example 1-2. Also, the cumulative replenishment amount at the 2 Ah / L time point is as follows. Nickel(II) sulfate hexahydrate: 29.3 g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 1.0 g / L Ammonium citrate tribasic: 66.9 g / L​​​​​​​​​​​​​​​The sodium concentration was adjusted by adding 78.1 g / L of sodium sulfate to the initial plating solution used in Example 1-1. Using this plating solution (sodium concentration of 1.5 mol / L), the sample substrate was subjected to Ni-W alloy plating under the same plating conditions as in Example 1-1. After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 41.2 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 2.5%.

[0040] (Example 3-2) Using the plating solution from Example 3-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 1.5 mol / L) at 125 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 125 minutes Cumulative current value: 4.8 × {125 / 60} / 1 = 10Ah / L Similar to Example 1-2, a simulated Ni-W alloy plating treatment (sacrificial plating) was performed on the sample substrate at 2Ah / L intervals until a plating time of 125 minutes was reached. To replenish the various components consumed in the sacrificial plating, the solution was replenished so that the concentrations of each component remained within the control range, similar to the control range shown in Example 1-2. Furthermore, the cumulative replenishment amount at 10Ah / L is as follows: Nickel(II) sulfate hexahydrate: 41.1 g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 4.8 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Tripotassium citrate monohydrate: 13.2 g / L Potassium formate: 56.0 g / L Sodium sulfate: 78.1 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 40.8 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 2.6%.

[0041] (Example 3-3) Using the plating solution from Example 3-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 1.5 mol / L) at 625 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 625 minutes Cumulative current value: 4.8 × {625 / 60} / 1 = 50Ah / L Similar to Example 1-2, a simulated Ni-W alloy plating treatment (sacrificial plating) was performed on the sample substrate at 2Ah / L intervals until a plating time of 625 minutes was reached. To replenish the various components consumed in the sacrificial plating, the solution was replenished so that the concentrations of each component remained within the control range, similar to the control range shown in Example 1-2. Furthermore, the cumulative replenishment amount at the 50Ah / L mark is as follows: Nickel(II) sulfate hexahydrate: 100.3g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 24.0 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Trisodium citrate monohydrate: 27.0 g / L Tripotassium citrate monohydrate: 16.5 g / L Sodium formate: 56.0 g / L Potassium formate: 42.1 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 40.2 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 3.1%.

[0042] (Comparative Example 1-1) The sodium concentration was adjusted by adding 99.4 g / L of sodium sulfate to the initial plating solution used in Example 1-1. Using this plating solution (sodium concentration of 1.8 mol / L), the sample substrate was subjected to Ni-W alloy plating under the same plating conditions as in Example 1-1. After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 39.9 wt%, the film thickness was 2.5 μm, and the corrosion area ratio was 16.0%.

[0043] (Comparative Example 1-2) Using the plating solution from Comparative Example 1-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 1.8 mol / L) at 125 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 125 minutes Cumulative current value: 4.8 × {125 / 60} / 1 = 10Ah / L Similar to Example 1-2, a simulated Ni-W alloy plating treatment (sacrificial plating) was performed on the sample substrate at 2Ah / L intervals until a plating time of 125 minutes was reached. To replenish the various components consumed in the sacrificial plating, the solution was replenished so that the concentrations of each component remained within the control range, similar to the control range shown in Example 1-2. Furthermore, the cumulative replenishment amount at 10Ah / L is as follows: Nickel(II) sulfate hexahydrate: 41.1 g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 4.8 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Tripotassium citrate monohydrate: 13.2 g / L Potassium formate: 56.0 g / L Sodium sulfate: 99.4 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 39.9 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 19.2%.

[0044] (Comparative Examples 1-3) Using the plating solution from Comparative Example 1-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 1.8 mol / L) at 625 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 625 minutes Cumulative current value: 4.8 × {625 / 60} / 1 = 50Ah / L Similar to Example 1-2, a simulated Ni-W alloy plating treatment (sacrificial plating) was performed on the sample substrate at 2Ah / L intervals until a plating time of 625 minutes was reached. To replenish the various components consumed in the sacrificial plating, the solution was replenished so that the concentrations of each component remained within the control range, similar to the control range shown in Example 1-2. Furthermore, the cumulative replenishment amount at the 50Ah / L mark is as follows: Nickel(II) sulfate hexahydrate: 100.3g / L Sodium tungstate(VI) dihydrate: 90.2 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Trisodium citrate monohydrate: 37.5 g / L Tripotassium citrate monohydrate: 4.9 g / L Sodium formate: 56.0 g / L Potassium formate: 42.1 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 39.8 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 21.3%.

[0045] (Comparative Example 2-1) Using the initial plating solution from Example 1-1, the sample substrate was subjected to Ni-W alloy plating under the following conditions with the plating solution (sodium concentration of 2.0 mol / L) at 25 minutes of plating time. Plating area: 0.4 dm² 2 Current density: 12A / dm 2 Current value: 4.8A Plating time: 25 minutes Cumulative current value: 4.8 × {25 / 60} / 1 = 2Ah / L Similar to Example 1-2, a simulated Ni-W alloy plating treatment (sacrificial plating) was performed on the sample substrate at 2Ah / L intervals until a plating time of 25 minutes was reached. To replenish the various components consumed in the sacrificial plating, the solution was replenished so that the concentrations of each component remained within the control range, similar to the control range shown in Example 1-2. Furthermore, the cumulative replenishment amount at 2Ah / L is as follows: Nickel(II) sulfate hexahydrate: 29.3g / L Sodium tungstate(VI) dihydrate: 66.0 g / L Potassium tungstate: 1.0 g / L Triammonium citrate: 66.9 g / L Citric acid monohydrate: 5.3g / L Tripotassium citrate monohydrate: 6.6 g / L Potassium formate: 44.9 g / L Sodium sulfate: 113.6 g / L After the plating process, the sample substrate was removed, and the W eutectoid rate, film thickness, and corrosion area ratio were calculated. As shown in Table 2, the W eutectoid rate was 39.8 wt%, the film thickness was 2.6 μm, and the corrosion area ratio was 24.3%. [Industrial applicability]

[0046] The Ni-W alloy plating film according to this embodiment has excellent corrosion resistance. The laminate containing the Ni-W alloy plating film according to this embodiment is suitable for use as connection terminals for semiconductor chips, as well as for electrical contacts and terminal components such as connectors, switches, and relays.

Claims

1. A method for producing a Ni-W alloy plated film, comprising using a plating solution containing nickel salt, tungsten salt, and citric acid components, setting the sodium concentration in the plating solution to 1.7 mol / L or less during initial adjustment, analyzing the concentration of each component in the plating solution for each predetermined cumulative current value, and replenishing each component in the plating solution so that it satisfies either equation (1) or (2) below, when the cumulative current value is x (Ah / L) and the sodium concentration is y (mol / L). (1) y≦0.060x+0.4 (0≦x≦21.6) (2) y≦1.7 (21.6<x)

2. A method for producing a Ni-W alloy plated film, comprising using a plating solution containing nickel salt, tungsten salt, and citric acid components, setting the sodium concentration in the plating solution to 1.7 mol / L or less during initial adjustment, analyzing the concentration of each component in the plating solution for each predetermined cumulative current value, and replenishing each component in the plating solution so that it satisfies equation (3) or (4) below, when the cumulative current value is x (Ah / L) and the sodium concentration is y (mol / L). (3) y≦0.030x+0.4 (0≦x≦43.3) (4) y≦1.7 (43.3<x)

3. A method for producing a Ni-W alloy plated film, comprising using a plating solution containing nickel salt, tungsten salt, and citric acid components, setting the sodium concentration in the plating solution to 1.7 mol / L or less during initial adjustment, analyzing the concentration of each component in the plating solution for each predetermined cumulative current value, and replenishing each component in the plating solution so that it satisfies equation (5) or (6) below, when the cumulative current value is x (Ah / L) and the sodium concentration is y (mol / L). (5) y≦0.014x+0.4 (0≦x≦92.8) (6) y≦1.7 (92.8<x)

4. A method for producing a Ni-W alloy plating film according to any one of claims 1 to 3, further comprising a formic acid component.

5. A method for producing a Ni-W alloy plating film according to any one of claims 1 to 3, further comprising a surfactant.

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