Plated member and method of manufacturing the same

Abstract

To provide a nickel-plated aluminum member (plated member) that is improved in uniformity and adhesion of plating, and can be manufactured in a dry method for preprocessing for plating.SOLUTION: There is provided a plated member that has a nickel plating film formed on aluminum base material made of aluminum or an aluminum alloy, and the plated member has: an aluminum member which has a hydrophilic primer layer including at least one kind of film consisting of a group of a hydrous oxide film including aluminum hydrous oxide and an oxide film including aluminum oxide, and a catalyst layer including a plating catalyst made of metal or metal oxide in this order on a surface of the aluminum base material; and a nickel plating film formed on the catalyst layer of the aluminum member, wherein the aluminum base material which has the hydrophilic primer layer formed on the surface has a surface roughness Rz of 2 to 15 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plated member in which a nickel plating film is formed on an aluminum substrate made of aluminum or an aluminum alloy, and to a method for producing the same. [Background technology]

[0002] Aluminum is lightweight, has excellent conductivity, and is an abundant resource, so in recent years, with the growing need for the electrification of automobiles and factory facilities, it has increasingly been used to replace conventional copper in bus bars, heat sinks, etc. Because aluminum forms an oxide film on its surface, it is often plated with nickel or other plating to reduce contact resistance when used as a bus bar, and to improve solder mountability when used in heat sinks, etc.

[0003] When plating aluminum and aluminum alloys (collectively referred to simply as aluminum), the insulating oxide film makes it difficult for the reduction reaction of plating metal ions to proceed on the aluminum surface. Furthermore, the metal layer formed on the oxide film has poor adhesion, making it difficult to achieve uniform, well-adhered plating on the aluminum surface. Therefore, as a pretreatment for plating, a zincate treatment is performed in which the aluminum material is immersed in a strong alkaline bath containing zinc, known as a zincate bath, which dissolves the oxide film on the aluminum surface and precipitates zinc particles, replacing the surface with zinc. The zinc particles precipitated by the zincate treatment act as a catalyst for the reduction reaction of the plating metal ions, accelerating the reduction reaction and depositing a metal layer on the zinc, resulting in uniform, well-adhered plating.

[0004] However, the plating process for aluminum materials, including zincate treatment, involves many steps and requires water rinsing between each step, resulting in higher wastewater treatment costs compared to plating for other materials such as copper. In particular, double zincate treatment, in which zincate treatment is performed twice to ensure uniform growth of zinc particles, is used. In this case, the number of water rinsing steps increases, further increasing wastewater treatment costs. Specifically, prior to zincate treatment, the aluminum material is degreased, etched, and desmutted. Each of these processes requires water rinsing (degreasing, "rinse," etching, "rinse," desmut, "rinse"). Furthermore, two zincate treatments involving zinc stripping also require water rinsing (primary zincate, "rinse," zinc stripping, "rinse," secondary zincate, "rinse").

[0005] Furthermore, in the case of electronic components and large bus bars, the areas requiring plating are limited, so partial plating is sometimes performed. However, plating on aluminum materials generally involves many treatment steps such as zincate treatment, and the baths used in each step are either strongly acidic or strongly alkaline, so there are only a limited number of masking materials that can withstand repeated immersion in such harsh treatment baths. In addition, masking large components or components with complex shapes is a time-consuming and expensive process, which is a problem.

[0006] Therefore, for example, in Patent Document 1, an underlayer made of an Al-Zn alloy is formed by sputtering as a catalyst for improving adhesion of Ni plating formed on a substrate made of aluminum or an aluminum alloy. Also, in Patent Document 1, in order to improve adhesion of Ni plating, a high roughness treatment is performed on the substrate surface by acid treatment to form the underlayer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-035428 Summary of the Invention [Problem to be solved by the invention]

[0008] In the above-mentioned Patent Document 1, instead of the wet zincate treatment, a catalyst for Ni plating is formed by a dry sputtering process. However, sputtering requires batch processing, which is not only time-consuming but also increases costs. Furthermore, in Patent Document 1, after the surface is roughened by acid treatment using an acid such as nitric acid, hydrochloric acid, or sulfuric acid, a base layer is formed by sputtering, which provides an anchor effect to ensure adhesion to the Ni plating. However, such acid treatment requires adjustment of the pH of the wastewater and recovery of metals and sludge, which increases the time and cost required for wastewater treatment, and various constraints arise even just in creating the working environment.

[0009] Therefore, an object of the present invention is to provide a nickel-plated aluminum member (hereinafter simply referred to as a plated member) that has improved adhesion of Ni plating and can be produced by a dry method for pretreatment before plating. Another object of the present invention is to provide a method for producing such a nickel-plated aluminum member. [Means for solving the problem]

[0010] That is, the gist of the present invention is as follows. [1] A plated member in which a nickel plating film is formed on an aluminum substrate made of aluminum or an aluminum alloy, An aluminum member having, on the surface of the aluminum base, a hydrophilic primer layer including at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrated oxide and an oxide film containing an aluminum oxide, and a catalyst layer including a plating catalyst made of a metal or a metal oxide, in this order; and The nickel plating film is formed on the catalyst layer of the aluminum member, the surface roughness Rz of the aluminum base material on which the hydrophilic primer layer is formed is 2 μm or more and 15 μm or less; A plated member characterized by: [2] The plated member according to [1], wherein the roughened surface area ratio of the aluminum base material on which the hydrophilic primer layer is formed is 80% or more and 100% or less. [3] The elemental profiles of aluminum, nickel, and oxygen obtained by EDX ray analysis of a cross section of the plated member are: The point where the aluminum element profile and the nickel element profile intersect is defined as the Al / Ni interface between the aluminum member and the nickel plating film, The plated member according to [1], wherein an oxygen intensity ratio, which is the ratio of the maximum oxygen intensity detected at the Al / Ni interface to the average value of the oxygen element profile intensity detected in a flat range of the nickel element profile intensity, is 1.5 or more and 50 or less. [4] The plated member according to [1], wherein the thickness of the hydrophilic primer layer is 1 nm or more and less than 1 μm. [5] The plated member according to [1], wherein the thickness of the catalyst layer is 2 nm or more and less than 1 μm. [6] In the plated member according to [1], The thickness of the nickel plating film is 1 μm or more and 1 mm or less, the nickel plating film is formed only on one or more portions of the aluminum base material, and is not formed on the remaining portions; Plated material used as a busbar. [7] The plated member according to any one of [1] to [6], wherein the metal is at least one metal selected from the group consisting of precious metals including gold, silver, and copper, platinum group metals including platinum and palladium, zinc, ruthenium, and rhodium. [8] The plated member according to any one of [1] to [6], wherein the metal is zinc. [9] A method for producing a plated member in which a nickel plating film is formed on an aluminum substrate made of aluminum or an aluminum alloy, comprising: a surface modification step of irradiating a surface of the aluminum base with laser light to roughen the surface of the aluminum base and form, on the surface of the aluminum base, a hydrophilic primer layer including at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrated oxide and an oxide film containing an aluminum oxide; a catalyst application step of applying a plating catalyst made of a metal or a metal oxide to the surface of the aluminum base on which the hydrophilic primer layer has been formed, to form a catalyst layer containing the plating catalyst on the surface of the aluminum base; a plating process step of performing a nickel plating process on the aluminum member having the hydrophilic primer layer and the catalytic layer formed on the surface of the aluminum base to form the nickel plating film on the catalytic layer of the aluminum member, The surface roughness Rz of the aluminum substrate on which the hydrophilic primer layer is formed in the surface modification step is 2 μm or more and 15 μm or less. A method for producing a plated member, comprising:

[10] The catalyst application step a coating step of coating the aluminum substrate with a catalyst solution or catalyst suspension containing a metal compound of the metal to adhere the metal compound to the aluminum substrate; and a calcination step of calcining the aluminum base having the metal compound adhered thereto to obtain an oxide of the metal from the metal compound on the surface of the aluminum base, thereby forming the plating catalyst.

[11] The method for producing a plated member according to

[10] , wherein the metal compound is an organic acid salt of the metal.

[12] The method for producing a plated member according to

[10] , wherein the firing temperature in the firing step is 180°C or higher and 500°C or lower.

[13] The catalyst application step a coating step of coating the aluminum substrate with a catalyst solution or catalyst suspension containing metal nanoparticles made of the metal or an oxide of the metal, thereby adhering the metal nanoparticles to the aluminum substrate; and a drying step of drying the aluminum base material to which the metal nanoparticles are attached to form the plating catalyst from the metal nanoparticles.

[14] The catalyst application step [9] The method for producing a plated member according to [9], further comprising a sputtering step of forming the plating catalyst by sputtering the metal to form a metal coating film made of the metal on the aluminum base.

[15] The method for producing a plated member according to [9], wherein in the plating step, the nickel plating is electroplating.

[16] The method for producing a plated member according to [9], wherein the metal is a metal that catalyzes the reduction reaction of nickel, among potentially noble metals that are insoluble in a nickel plating bath.

[17] The method for producing a plated member according to any one of [9] to

[16] , wherein the metal is at least one metal selected from the group consisting of precious metals including gold, silver, and copper, platinum group metals including platinum and palladium, zinc, ruthenium, and rhodium.

[18] The method for producing a plated member according to any one of [9] to

[16] , wherein the metal is zinc. [Effects of the Invention]

[0011] According to the present invention, a plated member having a nickel plating film can be obtained by using an aluminum substrate made of aluminum or an aluminum alloy and performing all pretreatments for plating, such as roughening the aluminum substrate and applying a plating catalyst, using dry methods. Therefore, compared with conventional methods using zincate treatment, the amount of wastewater generated during water rinsing can be significantly reduced, reducing the effort and cost required for wastewater treatment and providing advantages in terms of facilities, including environmental friendliness. Furthermore, the resulting plated member can have an excellent nickel plating film adhesion, which can promote its use as an aluminum substitute for copper in bus bars, heat sinks, and other applications. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1(a) is an enlarged photograph of the surface of an aluminum substrate roughened by irradiating it with laser light, and FIG. 1(b) is a schematic diagram illustrating how the roughened area ratio is determined. [Figure 2] Figure 2 is an enlarged photograph showing the wettability of an aluminum substrate. Figure 2(a) shows the wettability of an aluminum substrate without surface roughening, and Figure 2(b) shows the wettability of an aluminum substrate irradiated with laser light. [Figure 3] FIG. 3(a) is a schematic explanatory diagram showing the plating adhesion test, and FIG. 3(b) is a schematic diagram for explaining the process of determining the unpeeled plating area ratio. [Figure 4] FIG. 4(a) is a photograph showing the state of the solder wettability test, and FIG. 4(b) is an enlarged photograph showing the state of the actual solidified solder. [Figure 5] FIG. 5 is an example of an SEM photograph of a cross-sectional sample used to determine the oxygen intensity ratio at the interface between an aluminum member and a nickel plating film (Example 1). [Figure 6] FIG. 6 shows an example of an element profile used to determine the oxygen intensity ratio at the interface between the aluminum member and the nickel plating film (Example 1). [Figure 7] FIG. 7 is a graph showing the relationship between the roughened surface area ratio and the unpeeled plating area ratio of an aluminum substrate for plated members. [Figure 8] Figure 8 shows SEM photographs of the surface of an aluminum substrate irradiated with laser light [(a) 300x, (b) 1000x, (c) 3000x]. [Figure 9] FIG. 9 shows the results of EDX analysis of the surface of an aluminum substrate irradiated with laser light. [Figure 10] FIG. 10(a) is a cross-sectional SEM photograph showing the interface between the aluminum member and the nickel plating film, and FIG. 10(b) is an enlarged view of a portion of FIG. 10(a) (the area enclosed by the dashed line). [Figure 11]FIG. 11 is a cross-sectional SEM photograph showing the process of measuring the thickness of a hydrated oxide film on an aluminum member (Example 3). [Figure 12] Figure 12 shows SEM photographs of the surface of an aluminum substrate that has been treated with phosphate chromate ((a) is 1000x magnification, (b) is 3000x magnification). [Figure 13] FIG. 13 is a cross-sectional SEM photograph of a plated member having a nickel plating film. [Figure 14] FIG. 14(a) is a cross-sectional SEM photograph showing the interface between the aluminum member and the nickel plating film, and FIG. 14(b) is an enlarged view of a portion of FIG. 14(a). DETAILED DESCRIPTION OF THE INVENTION

[0013] The plated member of the present invention will be described in detail together with its manufacturing method. The components of the present invention described below can be combined in part or in whole as appropriate.

[0014] [1. Plating materials] The plated member of the present invention comprises an aluminum member having, on the surface of an aluminum base made of aluminum or an aluminum alloy, a hydrophilic primer layer comprising at least one film selected from the group consisting of a hydrated oxide film containing an aluminum oxide and an oxide film containing an aluminum oxide, in this order, and a catalyst layer containing a plating catalyst made of a metal or a metal oxide, and a nickel plating film formed on the catalyst layer of the aluminum member, and the aluminum base having the hydrophilic primer layer formed on its surface has a surface roughness Rz of 2 μm or more and 15 μm or less.

[0015] [1-1. Aluminum Components] <Aluminum substrate> The plated member of the present invention comprises an aluminum member and a nickel plating film, and the aluminum member has a hydrophilic primer layer and a catalyst layer, in that order, on the surface of the aluminum substrate. The aluminum substrate used in this aluminum member is made of aluminum or an aluminum alloy. There are various aluminum substrates, ranging from 100% pure aluminum to aluminum alloys with different types and amounts of alloying elements. The material is not limited and can be determined based on the application of the plated member to be formed using it and the various physical properties required for that application, such as strength, corrosion resistance, and workability. It is also possible to use processed materials obtained by appropriately processing them into the desired shape, or combined materials obtained by appropriately combining these processed materials.

[0016] Among these, when used as conductive members such as bus bars or cooling members such as heat sinks, for example, a wrought material that has excellent electronic and thermal conductivity and is easy to process is desirable, and among these, 1000 series alloys, 3000 series alloys, 5000 series alloys, and 6000 series alloys are preferably used. Furthermore, although there are no particular limitations as it depends on the application of the plated member, the thickness of the aluminum substrate can generally be approximately 0.3 mm to 40 mm.

[0017] The aluminum substrate typically has a surface roughness Rz of 2 μm or more and 15 μm or less. If the surface roughness Rz of the aluminum substrate is 2 μm or more, the adhesion of the final nickel plating film is improved. On the other hand, if the surface roughness Rz is 15 μm or less, the nickel plating film can be uniformly formed on the catalyst layer of the aluminum member. In other words, if the surface roughness Rz is equal to or greater than the lower limit, a so-called anchor effect is exhibited. However, if the surface roughness Rz exceeds the upper limit and the surface area of ​​the aluminum substrate increases excessively, the metal or metal compound forming the catalyst layer will not spread sufficiently, making it impossible to ensure uniform catalyst application. From this perspective, the surface roughness Rz of the aluminum substrate is preferably 3 μm or more, more preferably 4 μm or more, even more preferably 6 μm or more, and particularly preferably 8 μm or more, and is preferably 14 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less. Note that this surface roughness Rz represents the maximum height according to JIS B 0601-2001. The surface roughness Rz can be measured by the method described in the examples.

[0018] In the method for producing a plated member of the present invention, the surface of an aluminum substrate is roughened and a hydrophilic primer layer (described later) is formed on the surface, thereby performing surface modification. The "roughened area ratio (%)" can be calculated by dividing the total area of ​​the surface-modified regions of the aluminum substrate, namely, the regions that have been roughened and have been formed with a hydrophilic primer layer, by the area of ​​the plating region where a nickel plating film is to be formed. The roughened area ratio is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more, but preferably not more than 100%. When the roughening treatment is performed using only laser treatment, the "projected area of ​​the spots" formed by irradiation with laser light represents the total area of ​​the surface-modified regions, and the "projected area of ​​the roughened region," which is the sum of the spots and non-spot areas, represents the plating region. In this case, the roughened area ratio is calculated using the following formula: In addition, when other roughening treatments that do not involve the formation of a hydrophilic primer layer, such as sandblasting or wire brush grinding, are performed in addition to laser treatment, the "projected area of ​​the spot" formed by irradiation with laser light among the roughening-treated areas is taken to represent the total area of ​​the surface-modified areas, and the roughened area ratio is calculated in the same manner using the following formula. By ensuring that the roughened area ratio is within the above numerical range, the wettability of the aluminum substrate is improved by the hydrophilic primer layer, and the surface irregularities can more reliably exhibit the anchoring effect, further improving the adhesion of the nickel plating film. Roughened surface area ratio (%) = (projected area of ​​spot / projected area of ​​roughened treatment range) x 100

[0019] <Hydrophilic primer layer> The surface of the aluminum substrate is provided with a hydrophilic primer layer containing at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrate oxide and an oxide film containing an aluminum oxide. This hydrophilic primer layer plays a role in enhancing the wettability of a metal or metal oxide when a catalyst layer is formed thereon.

[0020] Generally, aluminum has a natural oxide film, an anodic oxide film formed by anodizing, or a rolled oxide film formed by hot rolling. In the present invention, to obtain an aluminum substrate having a predetermined surface roughness Rz, it is preferable to use a hydrated oxide film formed when roughening the surface of the aluminum substrate by irradiating it with laser light (as described below) (simultaneously with the roughening) as the hydrophilic primer layer. Alternatively, after forming a hydrated oxide film by irradiating it with laser light, the oxide film remaining after performing treatments such as removing the hydrated oxide film by phosphate chromate treatment or thinning the thickness of the hydrated oxide film may be used as the hydrophilic primer layer.

[0021] Furthermore, if electrical conductivity is required depending on the application of the plated member, the hydrated oxide film or oxide film forming the hydrophilic primer layer as described above may increase electrical resistance. In particular, when used as a conductive member such as a bus bar, problems such as heat generation can occur when a large current is passed through it. Taking these factors into consideration, the thickness of the hydrophilic primer layer is preferably less than 1 μm to prevent an increase in electrical resistance at the interface where the nickel plating film is formed and ensure electrical conductivity. On the other hand, the thickness of the hydrophilic primer layer is preferably 1 nm or more to enhance wettability in forming a catalyst layer. The thickness of the hydrophilic primer layer can be measured using the method described in the Examples. More specifically, when the hydrophilic primer layer is a hydrated oxide film containing aluminum hydrated oxide, the thickness of the hydrophilic primer layer is preferably less than 1 μm, more preferably 200 nm or less, even more preferably 100 nm or less, and preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. When the hydrophilic primer layer is an oxide film containing aluminum oxide, the hydrophilic primer layer is preferably 50 nm or less, more preferably 20 nm or less, even more preferably 10 nm or less, and preferably 1 nm or more, more preferably 3 nm or more, even more preferably 5 nm or more.

[0022] The plated member of the present invention has a nickel plating film formed on a catalytic layer via a hydrophilic primer layer provided on an aluminum substrate. Therefore, the presence of this hydrophilic primer layer improves the wettability of the aluminum substrate and, together with the catalytic layer described below, enhances the uniformity of the nickel plating film. The presence of such a hydrophilic primer layer can be confirmed as follows based on the elemental profiles of aluminum, nickel, and oxygen obtained by energy dispersive X-ray spectroscopy (EDX) of a cross section of the plated member.

[0023] An elemental profile of the cross section is obtained by performing EDX analysis along the thickness direction of a cross-sectional sample representing a cross section of the plated member. In this elemental profile, the point where the aluminum elemental profile and the nickel elemental profile intersect is defined as the interface between the aluminum member and the nickel plating film (Al / Ni interface). The oxygen intensity ratio [(ii) / (i)] is calculated from the ratio of the average oxygen elemental profile intensity (i) detected in the flat area of ​​the nickel elemental profile, which corresponds to the area where the nickel plating film is formed, to the maximum oxygen intensity (ii) detected at the Al / Ni interface. If this oxygen intensity ratio [(ii) / (i)] is 1.5 or greater, it is determined that an oxygen-containing film, such as a hydrated oxide film or oxide film, forming a hydrophilic primer layer is present. The oxygen intensity ratio is preferably 1.5 or greater, more preferably 2 or greater, and even more preferably 3 or greater. Considering the substantial amount of oxygen detected at the Al / Ni interface, the oxygen intensity ratio [(ii) / (i)] is preferably 50 or less. The oxygen intensity ratio is more preferably 20 or less, and further preferably 10 or less.

[0024] <Catalyst layer> A catalyst layer containing a plating catalyst made of a metal or metal oxide is provided on the hydrophilic primer layer. This catalyst layer functions as a catalyst for the reduction reaction of nickel when forming a nickel plating film. Metals that form such plating catalysts include, for example, precious metals made of gold, silver, and copper; platinum group metals made of platinum and palladium; zinc; ruthenium; rhodium; or at least one or more metals selected from the group consisting of these. Among these, an electrically noble metal that does not dissolve in a nickel plating bath is preferred, and preferably a precious metal made of gold, silver, and copper, a platinum group metal made of platinum and palladium, or at least one or more metals selected from the group consisting of these.

[0025] The catalyst layer may be formed as a film made of a metal or metal oxide, or may be formed as particles made of a metal or metal oxide. Examples include those formed by sputtering. Other examples include those formed by heat treatment using a solution or suspension containing a catalyst precursor, such as by applying a copper acetate aqueous solution and then heat treating (calcining) to precipitate copper acetate. Other examples include those formed by applying a liquid dispersion of metal particles, such as metal nanoparticles, and then drying it. The catalyst layer may be formed as a film by sputtering, or as a particulate or fibrous form using a solution or suspension containing a catalyst precursor, or as a particulate form using a liquid dispersion of metal particles. The catalyst layer need only be formed on at least a portion of the aluminum substrate having a hydrophilic primer layer, and does not necessarily have to be formed on the entire aluminum substrate. However, from the viewpoint of improving the adhesion of the nickel plating film, it is desirable for the catalyst layer to be formed on the entire hydrophilic primer layer formed on the surface of the aluminum substrate.

[0026] The thickness of the catalyst layer is not particularly limited as long as it successfully forms a nickel plating film. However, considering the above-mentioned function as a catalyst for the nickel reduction reaction more reliably, the thickness is preferably 2 nm or more, preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 100 nm or more. On the other hand, in the case of metal oxides, for example, copper(I) oxide has electronic conductivity but higher resistance than metals. Therefore, there is a risk of increasing electrical resistance due to the catalyst layer. Therefore, considering the use of the plated member as a conductive member, the thickness is preferably less than 1 μm, more preferably 500 nm or less, and even more preferably 200 nm or less. Incidentally, when the catalyst layer is a film made of metal oxide, the small linear expansion coefficient of metal oxides causes a significant internal stress at the interface due to the difference in linear expansion coefficient under a thermal cycle environment. This may cause cracks at the interface with the aluminum substrate, the interface with the nickel plating film, or within the catalyst layer, resulting in plating peeling. However, a thickness of the catalyst layer less than 1 μm makes it easier to prevent such plating peeling. When the catalyst layer is made of metal, these problems are unlikely to occur, but from an economical viewpoint, such as the saturation of the effect, it can be said that the upper and lower limits of the thickness should be approximately the same as those described above.

[0027] The weight of the catalyst layer is not particularly limited as long as a nickel plating film is formed satisfactorily, but is preferably 0.002 g / m 2 More preferably, 0.02 g / m 2 More preferably, 0.1 g / m 2 or more, and preferably 100 g / m 2 Less than 10 g / m, more preferably 2 More preferably, it is 2 g / m or less. 2or less. When the basis weight of the catalyst layer is equal to or greater than the lower limit of the above-mentioned range, the catalyst layer more reliably functions as a catalyst for the nickel reduction reaction as described above. Furthermore, when the basis weight of the catalyst layer is equal to or less than the upper limit of the above-mentioned range, an increase in electrical resistance due to the catalyst layer is suppressed, making it easier to use the plated member as a conductive member and preventing an increase in costs associated with forming the catalyst layer. Furthermore, when the catalyst layer is a film made of a metal oxide, plating peeling due to the small linear expansion coefficient of the metal oxide is more likely to be prevented.

[0028] [1-2. Nickel plating film] The plated member of the present invention includes a nickel plating film formed on a catalyst layer of an aluminum member. This nickel plating film may be formed on a catalyst layer via a hydrophilic primer layer provided on at least a portion of the aluminum substrate. The entire surface of the plated member may not be covered with the nickel plating film, but may be partially covered. The thickness of the nickel plating film is not particularly limited. However, to obtain a nickel plating film with excellent electronic and thermal conductivity, for example, for use as a conductive member such as a bus bar or a cooling member such as a heat sink, the thickness of the nickel plating film is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. While a thicker nickel plating film is more advantageous in terms of these properties, from an economical standpoint, such as the saturation of the effect, the thickness of the nickel plating film is preferably 1 mm or less, more preferably 500 μm or less, and even more preferably 100 μm or less.

[0029] Here, when the plated member of the present invention is used as a busbar for branching large currents in a switchboard or control panel, as described above, the thickness of the nickel plating film is preferably 1 μm or more and 1 mm or less, and the nickel plating film is preferably formed only at the contact points with the connection terminals in the switchboard or control panel, corresponding to partial plating. In other words, considering cost, it is not necessary for the nickel plating film to be present in the remaining areas other than the contact points. Note that the areas without the nickel plating film may be configured so that no hydrophilic primer layer or catalyst layer is formed, or one or both of these may be present, with only the nickel plating film not being formed.

[0030] [2. Manufacturing method for plated components] The method for producing a plated member of the present invention includes a surface modification step of irradiating the surface of an aluminum substrate made of aluminum or an aluminum alloy with laser light to roughen the surface of the aluminum substrate and form a hydrophilic primer layer on the surface of the aluminum substrate, the hydrophilic primer layer comprising at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrated oxide and an oxide film containing an aluminum oxide; a catalyst application step of applying a plating catalyst made of a metal or metal oxide to the surface of the aluminum substrate on which the hydrophilic primer layer has been formed, to form a catalyst layer containing the plating catalyst; and a plating step of nickel plating the aluminum member, on which the hydrophilic primer layer and catalyst layer have been formed on the surface of the aluminum substrate through these steps, to form a nickel plating film on the catalyst layer of the aluminum member, so that the surface roughness Rz of the aluminum substrate on which the hydrophilic primer layer has been formed in the surface modification step is 2 μm or more and 15 μm or less.

[0031] [2-1. Surface modification process] First, in the surface modification step, the surface of the aluminum substrate is irradiated with laser light to roughen the surface of the aluminum substrate and form the aforementioned hydrophilic primer layer on the surface of the aluminum substrate. Laser treatment by irradiating laser light is expected to have a cleaning effect such as blowing away grease and dirt adhering to the surface of the aluminum substrate and decomposing organic matter, so there is no need for degreasing, etching, or desmutting, which are performed prior to the conventional zincate treatment, and there is also no need for the accompanying water washing.

[0032] In addition, in laser treatment using laser light irradiation, the aluminum substrate is roughened to a surface roughness Rz of 2 μm or more and 15 μm or less, and at the same time, a hydrated oxide film containing aluminum hydrated oxide is formed on the surface of the aluminum substrate by reacting with moisture in the air. There are no particular limitations on the conditions for this laser treatment as long as the above-mentioned surface roughness Rz is obtained, and the hydrated oxide film is formed accordingly, but it is preferable to use a laser device that can oscillate a near-infrared laser with a wavelength of about 600 to 1500 nm, for example.

[0033] This laser treatment forms a hydrated oxide film containing hydrated aluminum oxide on the surface of the aluminum substrate. This hydrated oxide film can be used directly as a hydrophilic primer layer for forming a catalyst layer in a subsequent catalyst application process. However, to reduce the thickness of the hydrophilic primer layer and improve electrical conductivity, the hydrated oxide film can be removed using an aqueous phosphochromic acid solution, and the remaining oxide film containing aluminum oxide can be used as the hydrophilic primer layer. The treatment using the aqueous phosphochromic acid solution is not particularly limited, and can be similar to the well-known phosphochromic acid treatment using a mixed aqueous solution containing phosphoric acid and chromic acid. For the phosphochromic acid treatment, for example, the test solution, test equipment, test pretreatment, and test procedure described in JISH8688:2013, "Method for measuring the mass per unit area of ​​anodized oxide films on aluminum and aluminum alloys," can be used.

[0034] In this surface modification step, including the case where treatment with an aqueous phosphochromate solution is performed, it is preferable that the thickness of the hydrophilic primer layer containing at least one film selected from the group consisting of a hydrated oxide film containing aluminum hydrated oxide and an oxide film containing aluminum oxide is set to be 1 nm or more and less than 1 μm.

[0035] In the surface modification step, it is desirable to improve the wettability of the aluminum substrate with a hydrophilic primer layer, and to more reliably exert an anchoring effect with the surface irregularities, thereby further improving the adhesion of the nickel plating film. From this perspective, it is desirable that the total area of ​​the spots that have been actually irradiated with laser light and have undergone surface modification within the plating treatment range be 80% or more and 100% or less in terms of the roughened area ratio, which is expressed by the following formula: Roughened surface area ratio (%) = (projected area of ​​spot / projected area of ​​roughened treatment range) x 100

[0036] [2-2. Catalyst application process] Next, in the catalyst application step, a plating catalyst composed of a metal or metal oxide is applied to the surface of the aluminum substrate on which the hydrophilic primer layer has been formed, thereby forming a catalyst layer containing the plating catalyst on the surface of the aluminum substrate. As described above, the catalyst layer functions as a catalyst for the reduction reaction of nickel when forming a nickel plating film. Therefore, the metal forming the metal or metal oxide is preferably, for example, a noble metal composed of gold, silver, and copper; a platinum group metal composed of platinum and palladium; zinc; ruthenium; rhodium; or at least one or more metals selected from the group consisting of these. Among these, an electrically noble metal that does not dissolve in a nickel plating bath is preferable. Preferably, the noble metal is a noble metal composed of gold, silver, and copper; a platinum group metal composed of platinum and palladium; or at least one or more metals selected from the group consisting of these.

[0037] There are no particular limitations on the method for forming a catalyst layer containing a plating catalyst on the surface of an aluminum base material, but examples include the following first to third catalyst application methods.

[0038] <First catalyst application method> That is, the first catalyst application method includes a coating step of coating an aluminum substrate with a catalyst solution (catalyst precursor solution) or catalyst suspension (catalyst precursor suspension) containing a metal compound of the metal that forms the plating catalyst, thereby adhering the metal compound to the aluminum substrate, and a calcination step of calcining the aluminum substrate with the adhering metal compound to obtain an oxide of the metal, thereby forming a catalyst layer that serves as the plating catalyst on the surface of the aluminum substrate. From the viewpoint of uniformly applying the metal compound, it is preferable to apply a catalyst solution. In this specification, a catalyst solution refers to a solution in which a metal component, which is a precursor to the catalyst, is dissolved in a solvent and present in a uniformly dispersed state. A catalyst suspension refers to a solution in which a metal component, which is a precursor to the catalyst, is present in a non-uniformly dispersed state, but not dissolved in a solvent.

[0039] This method of applying a catalyst solution or catalyst suspension and baking it allows the plating catalyst to be applied to the surface of the aluminum substrate without the need for water rinsing. Furthermore, since the hydrophilic primer layer formed on the surface of the aluminum substrate in the previous surface modification step enhances wettability, the plating catalyst can be applied uniformly, improving the area ratio of the nickel plating film. In particular, this method is advantageous in terms of productivity, since the plating catalyst can be applied over a large area.

[0040] Here, the metal forming the plating catalyst contained in the metal compound used in the application step of the first catalyst application method is preferably, as described above, a noble metal consisting of gold, silver, and copper; a platinum group metal consisting of platinum and palladium; zinc; ruthenium; rhodium; or an organic acid salt of at least one or more metals selected from the group consisting of these. Among these, any metal that is electrically noble and insoluble in the nickel plating bath and catalyzes the reduction reaction of nickel is sufficient, and preferably one or more of the noble metals gold, silver, and copper, and the platinum group metals such as platinum and palladium are preferred. Copper is particularly suitable for use in the first catalyst application method.

[0041] The metal compound used in the coating step of the first catalyst application method may be an organic acid salt. That is, the first catalyst application method may include a coating step of coating an aluminum base with a catalyst solution or catalyst suspension containing an organic acid salt of a metal that forms a plating catalyst, thereby adhering the organic acid salt to the aluminum base, and a calcination step of calcining the aluminum base with the organic acid salt adhered thereto to obtain an oxide of the metal, thereby forming a catalyst layer that serves as a plating catalyst on the surface of the aluminum base. Organic acid salts are suitable because they are soluble in inexpensive solvents such as water and ethanol and are less harmful, producing harmful substances such as nitrogen oxides, sulfur oxides, and halogen compounds during calcination.

[0042] Examples of organic acids constituting organic acid salts include carboxylic acids such as formic acid, acetic acid, propionic acid, and butyric acid; dicarboxylic acids such as succinic acid, fumaric acid, maleic acid, and adipic acid; and hydroxy acids such as lactic acid, tartaric acid, malic acid, citric acid, and gluconic acid. Specific examples of organic acid salts using copper, one of the noble metals and platinum group metals mentioned above, include copper formate [(HCOO)2Cu·4H2O], copper acetate [(CH3COO)2Cu·H2O], copper propionate [Cu(C2H5COO)2·H2O], copper citrate [C6H4O7Cu2·2.5H2O], copper lactate [Cu(C3H5O3)2·2H2O], copper tartrate [CuC4H4O6·3H2O], In addition to copper gluconate [[HOCH2(HCOH)4COO]2Cu] and copper oxalate [CuC2O4·0.5H2O], examples include copper fumarate, copper maleate, copper adipate, copper malate, copper succinate, and copper butyrate. One or more of these can be used, and among these, copper formate, copper acetate, copper propionate, copper lactate, copper tartrate, copper citrate, and copper gluconate are preferred.

[0043] Furthermore, there are no particular limitations on the means for adhering the metal compound to the aluminum substrate in this coating step, and examples thereof include known methods such as immersion, spray coating, dropping, ink jetting, and flow coating.

[0044] The concentration of the organic acid salt contained in the catalyst solution or catalyst suspension used in the first catalyst application method is preferably 0.01 mol / L or more, more preferably 0.05 mol / L, even more preferably 0.1 mol / L or more, particularly preferably 0.2 mol / L or more, and preferably 0.8 mol / L or less, more preferably 0.6 mol / L or less, even more preferably 0.4 mol / L or less, particularly preferably 0.3 mol / L or less. When the concentration of the organic acid salt contained in the catalyst solution or catalyst suspension is equal to or greater than the above-mentioned lower limit, the surface of the aluminum substrate is supplied so that metal ions of the metal that forms the plating catalyst cover the entire surface, thereby forming a plating catalyst continuously over the entire area to be plated, thereby increasing the plating area ratio. When the concentration of the organic acid salt contained in the catalyst solution or catalyst suspension is equal to or less than the above-mentioned upper limit, the organic acid salt is less likely to remain dissolved in the solution, making it easier to uniformly apply the organic acid salt to the area to be plated.

[0045] On the other hand, the calcination step in the first catalyst application method is not particularly limited as long as it is a heat treatment that can obtain an oxide of the metal from the metal compound attached to the surface of the aluminum substrate. For example, continuous heating using an electric furnace or heat gun may be performed. To minimize the thermal impact on the aluminum substrate, flash heating using infrared light or a xenon flash lamp or infrared gold image furnace may be used. The specific heat treatment temperature (calcination temperature) in this calcination step can be appropriately set depending on the type of metal compound, but it is desirable to set temperature conditions that avoid softening of the aluminum substrate due to heating. For example, when obtaining copper oxide from the aforementioned organic acid salt of copper, the heat treatment temperature is preferably 180°C or higher, more preferably 200°C or higher, even more preferably 250°C or higher, and particularly preferably 300°C or higher, and is preferably 500°C or lower, more preferably 450°C or lower, and even more preferably 400°C or lower.

[0046] <Second catalyst application method> Furthermore, a second catalyst application method for forming a catalyst layer containing a plating catalyst on the surface of an aluminum substrate includes a coating step in which a catalyst solution or catalyst suspension (slurry) containing metal nanoparticles made of a metal or metal oxide that forms the plating catalyst is applied to the aluminum substrate to adhere the metal nanoparticles to the aluminum substrate, and a drying step in which the aluminum substrate with the adhered metal nanoparticles is dried to form a catalyst layer that becomes a plating catalyst made of metal nanoparticles.

[0047] As described above, the metal forming the plating catalyst contained in the metal nanoparticles used in this second catalyst application method is preferably a noble metal consisting of gold, silver, and copper; a platinum group metal consisting of platinum and palladium; zinc; ruthenium; rhodium; or at least one or more metals selected from the group consisting of these. Among these, any metal that is electrically noble and does not dissolve in a nickel plating bath and catalyzes the reduction reaction of nickel is preferred, and preferably one or more of the noble metals gold, silver, and copper, and the platinum group metals such as platinum and palladium are preferred. In particular, silver or zinc is preferably used in the second catalyst application method.

[0048] The metal nanoparticles contained in the catalyst suspension are preferably particles made of a metal that forms the plating catalyst, or particles made of an oxide of the metal that forms the plating catalyst. Particles made of a metal refer to metals that exist as simple substances and are not present in the form of metal compounds such as metal oxides, metal sulfides, or metal chlorides. Among the metal nanoparticles contained in the catalyst suspension, examples of metal particles include particles containing gold, silver, copper, platinum, palladium, zinc, ruthenium, rhodium, etc. Among the metal nanoparticles contained in the catalyst suspension, examples of metal oxide particles include particles containing silver oxide, copper oxide, platinum oxide, palladium oxide, zinc oxide, ruthenium oxide, rhodium oxide, etc.

[0049] The average particle size of the metal nanoparticles is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and is preferably 500 nm or less, more preferably 100 nm or less, even more preferably 40 nm or less.

[0050] When applying such a catalyst solution or catalyst suspension containing metal nanoparticles, known methods such as immersion, spray coating, dripping, inkjet, and flow coating can be used, as in the application step of the first catalyst application method described above. Furthermore, in the second catalyst application method, the metal nanoparticles contained in the catalyst solution or catalyst suspension are applied to the aluminum substrate and directly serve as a plating catalyst, so the drying step after the application step can be a heat treatment required to volatilize the solvent. In other words, baking after application of the catalyst solution or catalyst suspension is not required.

[0051] For example, a commercially available marker pen containing silver nanoparticle ink (manufactured by Mitsubishi Paper Mills under the trade name Circuitry Marker) can be used as a catalyst solution containing such metal nanoparticles. In this case, the silver nanoparticle ink is applied to the required areas on the surface of the aluminum substrate, and the solvent evaporates during subsequent natural drying. This allows the ink application to immediately become a drying step, thereby forming a catalyst layer containing a plating catalyst.

[0052] When a catalyst suspension containing metal nanoparticles is applied, it tends to be more difficult to uniformly apply the catalyst to the aluminum substrate than when a catalyst solution is applied. For this reason, it is preferable to include a sweeping step in which, after applying the catalyst suspension to the aluminum substrate, the suspension is spread over the surface of the aluminum substrate and excess suspension present on the surface of the aluminum substrate is removed. That is, it is preferable to include a coating step in which the catalyst suspension is applied to the aluminum substrate to attach metal nanoparticles to the aluminum substrate, a sweeping step in which the suspension applied to the aluminum substrate is swept away, and a drying step in which the aluminum substrate with the attached metal nanoparticles is dried to form a catalyst layer that serves as a plating catalyst made of metal nanoparticles.

[0053] In the second catalyst application method, the amount of catalyst suspension remaining on the surface of the aluminum substrate per unit area is controlled by performing a sweeping step of sweeping the suspension present on the surface of the aluminum substrate. Therefore, by adjusting the concentration of the catalyst suspension to be dripped, the amount of metal nanoparticles remaining on the surface of the aluminum substrate per unit area can be controlled.

[0054] The concentration of metal nanoparticles contained in the catalyst suspension used in the second catalyst application method is preferably 6% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, particularly preferably 12% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less. When the concentration of metal nanoparticles contained in the catalyst suspension is equal to or greater than the above-mentioned lower limit, zinc oxide particles are applied to the entire surface of the aluminum base, and the zinc oxide particles are present in a dense state on the surface of the aluminum base, resulting in the continuous formation of a catalyst layer, which facilitates the formation of a catalyst layer that covers the entire plating area. When the concentration of metal nanoparticles contained in the catalyst suspension is equal to or less than the above-mentioned upper limit, the viscosity of the catalyst suspension is reduced, allowing the catalyst suspension to be applied uniformly to the entire plating area, and this helps prevent the occurrence of an uneven plating film and poor appearance due to the application of excessive metal nanoparticles in some areas.

[0055] The operation of sweeping the suspension applied to the aluminum substrate can be carried out by bringing a plate-like or spatula-like sweeping member into contact with the suspension and moving the sweeping member in contact with the suspension. In this case, it is preferable to move the sweeping member at a constant speed.

[0056] The scanning speed of the sweeping member is preferably 5 mm / s or more, more preferably 10 mm / s or more, even more preferably 12 m / s or more, particularly preferably 15 m / s or more, and is preferably 50 mm / s or less, more preferably 30 mm / s or less, even more preferably 25 m / s or less, and particularly preferably 20 m / s or more. By setting the scanning speed at or above the lower limit, excess suspension present on the surface of the aluminum base material can be removed while leaving metal nanoparticles for forming a catalyst layer that covers the entire area to be plated. By setting the scanning speed at or below the upper limit, it becomes easier to prevent poor appearance due to an inhomogeneous plating film being formed, which is caused by the application of more metal nanoparticles than necessary to the surface of the aluminum base material.

[0057] A squeegee (spatula) can be used as the sweeping member. Alternatively, an elastic sheet-like member may be used as the sweeping member. An elastic sheet-like member is preferred from the viewpoint of allowing the sweeping member to follow slight irregularities in the aluminum substrate and alleviating the load applied by the sweeping member by utilizing the elasticity of the sweeping member. For example, a resin sheet, a silicone sheet, a rubber sheet, a metal sheet, etc. can be used as the sweeping member. Among these, a silicone sheet is preferred because of its high elasticity and low reactivity with the suspension. When the sweeping member is a silicone sheet, the thickness of the sweeping member is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more, and preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0058] <Third catalyst application method> Furthermore, a third catalyst application method for forming a catalyst layer containing a plating catalyst on the surface of an aluminum substrate includes a sputtering step in which the aforementioned metal is sputtered to form a metal film on the aluminum substrate, thereby forming a catalyst layer that will serve as a plating catalyst. According to the third catalyst application method, a catalyst layer that is relatively thin and has a low coating weight can be formed in a dense form with few defects.

[0059] As described above, the metal forming the plating catalyst to be sputtered in the third catalyst application method is preferably a noble metal consisting of gold, silver, and copper; a platinum group metal consisting of platinum and palladium; zinc; ruthenium; rhodium; or at least one or more metals selected from the group consisting of these. Among these, any metal that is electrically noble and does not dissolve in a nickel plating bath and catalyzes the reduction reaction of nickel is preferred, and preferably one or more of the noble metals gold, silver, and copper, and the platinum group metals such as platinum and palladium are preferred. In particular, gold, platinum, or palladium, which are relatively expensive, can be suitably used in the third catalyst application method.

[0060] The thickness of the catalyst layer formed as a plating catalyst on the surface of the aluminum substrate by these methods is as described above, and is preferably 2 nm or more and less than 1 μm whether it is made of a metal oxide or a metal. In particular, when the catalyst layer is formed by the first catalyst application method and the second catalyst application method described above, the thickness of the catalyst layer is preferably 10 nm or more, more preferably 50 nm or more, even more preferably 100 nm or more, and preferably less than 1 μm, more preferably 500 nm or less, and even more preferably 200 nm or less. Furthermore, when the catalyst layer is formed by the third catalyst application method described above, the thickness of the catalyst layer is preferably 2 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less.

[0061] The coating weight of the catalyst layer formed on the surface of the aluminum substrate by the above-mentioned method is as described above, and is preferably 0.002 g / m 2 or more, and preferably 100 g / m 2 In particular, when the catalyst layer is formed by the first catalyst application method and the second catalyst application method described above, the basis weight of the catalyst layer is preferably 0.01 g / m 2 More preferably, 0.05 g / m 2 More preferably, 0.1 g / m 2 or more, and preferably 100 g / m 2 Less than 50 g / m 2 More preferably, 10 g / m or less 2 When the catalyst layer is formed by the third catalyst application method described above, the weight of the catalyst layer is preferably 0.002 g / m or less. 2 More preferably, 0.001 g / m 2 More preferably, 0.02 g / m 2 or more, preferably 20 g / m 2 Less than 5g / m, more preferably 2 More preferably, 2 g / m or less 2 The following is the result.

[0062] Furthermore, the catalyst layer made of the plating catalyst applied to the surface of the aluminum material in the catalyst application step may be applied partially to a location where a nickel plating film is required depending on the application of the plated member, or may be applied to the entire surface of the aluminum material.

[0063] [2-3. Plating process] Next, in the plating process, the aluminum member, on which the hydrophilic primer layer and catalyst layer have been formed on the surface of the aluminum substrate by the surface modification process and catalyst application process, is subjected to a nickel plating process to form a nickel plating film on the catalyst layer of the aluminum member. The plating process here can be performed using the same method as for forming nickel plating films, and a known plating bath (plating solution) can be used. It can also be electroplating or electroless plating. However, when used as a conductive member such as a bus bar or a cooling member such as a heat sink, it is preferable to form the nickel plating film by electroplating, as it provides excellent corrosion resistance. In the present invention, the presence of the catalyst layer formed by the catalyst application process suppresses the generation of hydrogen as a side reaction during the plating process, allowing for efficient reduction of nickel, thereby reducing electrical energy and suppressing decomposition of the plating bath.

[0064] In the present invention, as described above, the nickel plating film may be provided only on a part of the aluminum member (partial plating). When performing partial plating, in which the nickel plating film is provided only on a part of the aluminum member, the aluminum member may be immersed in a plating bath after masking the areas where the nickel plating film is not required.

[0065] Alternatively, brush plating can be used as a method for selective plating without the need for masking. Brush plating is an electroplating method in which a cloth or the like soaked in plating solution is wrapped around a metal rod connected to a power source and then brought into contact with the areas requiring selective plating. Brush plating eliminates the need to mask areas where a plating film is not required. This also makes it possible to simply clean the areas that come into contact with the plating solution, thereby reducing the amount of post-plating cleaning and the associated wastewater treatment.

[0066] Furthermore, as mentioned above, there are no particular restrictions on the thickness of the nickel plating film, but when used as a conductive member such as a bus bar or a cooling member such as a heat sink, the thickness is preferably 1 μm or more and 1 mm or less.

[0067] [3. Action and Effects] In the plated member of the present invention, the surface of the aluminum substrate is roughened, thereby improving the adhesion of the nickel plating film through the anchoring effect. Moreover, in the present invention, since the nickel plating film is formed on the aluminum substrate via a hydrophilic primer layer and a catalyst layer, a plated member having a uniform plating film can be provided due to the hydrophilic effect of the hydrated oxide film or oxide film.

[0068] Furthermore, according to the plated member of the present invention, a nickel plating film is formed on an aluminum substrate, and thus a plated member having excellent contact resistance can be provided that is lighter in weight than a copper substrate that is mainly used for, for example, bus bars, etc. Furthermore, according to the present invention, the surface modification of the aluminum substrate is carried out by dry treatment using laser light irradiation, and therefore wet pretreatment involving water washing in zincate treatment is not required, and it is possible to provide a plated member with a significantly reduced amount of wastewater.

[0069] Furthermore, in the method for producing a plated member of the present invention, the surface of the aluminum substrate is roughened by laser treatment using laser light irradiation, thereby improving the adhesion of the nickel plating due to the anchoring effect. This eliminates the need for wet pretreatments that involve water washing, such as zincate treatment, and significantly reduces the amount of wastewater. In particular, in the method for producing a plated member of the present invention, the surface modification step using laser treatment removes an oxide film on the surface of the aluminum substrate and forms a hydrated oxide film. This improves wettability with a solution or suspension containing a metal compound or metal particles in the catalyst application step, allowing the formation of a uniform and extremely thin catalyst deposition layer (catalyst layer), thereby improving the adhesion of the nickel plating film formed thereafter.

[0070] Furthermore, in the method for producing a plated member of the present invention, by forming a catalyst layer on the surface of the aluminum member, the generation of hydrogen as a side reaction during the plating process is suppressed, and nickel is efficiently reduced, thereby reducing electrical energy and suppressing decomposition of the plating bath. Moreover, in the method for producing a plated member of the present invention, the surface modification process is performed by irradiating with laser light, so the surface modification process can be performed on only a portion of the aluminum base material. Furthermore, by performing the catalyst application process and plating process following the surface modification process only on a portion of the aluminum base material, partial plating is possible. [Example]

[0071] Preferred embodiments of the present invention will be specifically described below based on examples, comparative examples, and test examples, but the present invention should not be construed as being limited thereto.

[0072] [Evaluation method] <1. Surface roughness of aluminum substrate> Using a Keyence VHX-6000 digital microscope, 500x 3D depth composite data was created, and the roughness (maximum height Rz in accordance with JIS B 0601-2001) of the aluminum substrate after laser treatment was calculated from the profile of an arbitrary straight line approximately 600 μm long within the data.

[0073] <2. Roughened surface area ratio of aluminum substrate> The roughened surface area ratio was calculated from 500x images using a Keyence VHX-6000 digital microscope. The roughened surface area ratio is expressed by the following formula, calculated by dividing the projected area of ​​the spot (irradiated area) formed on the surface of the aluminum substrate by the projected area of ​​the area to be roughened. Figure 1(a) shows an enlarged photograph of an aluminum substrate that was roughened by laser irradiation. Figure 1(b) is a schematic diagram illustrating the process of calculating the roughened surface area ratio. A roughened surface area ratio of 100% was evaluated as ○ (good), 80% or more as △ (passable), and less than 80% as × (unacceptable). Roughened surface area ratio (%) = (projected area of ​​spot / projected area of ​​roughened treatment range) x 100

[0074] <3. Wettability of aluminum substrate> After laser treatment of the aluminum substrate, when the treatment liquid (copper oxide aqueous solution or silver nanoink) used in the catalyst application process is applied, if the wettability is poor, the droplets will not spread over the entire surface of the aluminum substrate, but will remain in only a small area and dry, resulting in the formation of a thick, uneven catalyst layer.On the other hand, if the wettability is excellent, the droplets will spread over the entire surface of the aluminum substrate evenly, resulting in the formation of a thin, uniform catalyst layer.

[0075] To evaluate the wettability of each aluminum substrate in the examples and comparative examples, 2 μL of ion-exchanged water was dropped onto the aluminum substrate and the contact angle was measured using the θ / 2 method with a Kyowa Interface Science automatic contact angle meter DMo-602. Contact angles were measured at three points on the surface of the same substrate and the average value was calculated. An average contact angle of less than 20° was considered acceptable, and an average contact angle of 20° or greater was considered unacceptable. Figure 4 shows an example of the wettability in a magnified photograph. Figure 2(a) shows the aluminum substrate without laser light irradiation, and Figure 2(b) shows the aluminum substrate with laser light irradiation.

[0076] <4. Basis weight of catalyst layer> The weight of the catalyst layer formed on the surface of the aluminum substrate was evaluated. The weight of the aluminum substrate was measured before and after the catalyst application step, and the difference between the weights before and after was taken as the weight of the catalyst layer.

[0077] <5. Plating uniformity> The nickel plating film formed on the surface of the aluminum substrate was visually evaluated, and a test piece was judged to pass if the plating film was formed over the entire surface (100%) of the roughened and catalyzed target area, and a test piece was judged to fail if there was even a small area where the plating was not applied.

[0078] <6. Plating Adhesion Test> To evaluate the adhesion of nickel plating films to aluminum substrates, the following adhesion test was conducted. Specifically, in accordance with JIS H8504:1999 "Test Methods for Adhesion of Plating," Section 15.1, Tape Test Method, Nichiban cellophane tape was applied to the plated surface of the sample, pulled strongly perpendicular to the plated surface, and then instantly peeled off. Visual inspection determined whether the plating remained completely on the aluminum substrate, whether it was good (○), whether it was fair (△), or whether it was less than 90% (more than 10% of the plating had peeled off). Furthermore, after peeling off the cellophane tape, the unpeeled plating area ratio, which indicates the percentage of the area of ​​the plated film that remained unpeeled relative to the tape-attached area, was calculated using the following formula: Figure 3(a) shows a schematic diagram of this adhesion test, and Figure 3(b) shows a schematic diagram of how the unpeeled plating area ratio was calculated. Unpeeled plating area rate (%) = (unpeeled plating area / tape-attached area) x 100

[0079] <7. Solder wettability test> Conductive members such as bus bars often have terminals mounted on their surfaces using solder. Generally, aluminum has poor solder wettability. Therefore, the improvement in solder wettability when a nickel plating film is formed on an aluminum substrate for the purpose of improving the solder wettability was evaluated as follows. First, the plated members obtained in the examples and comparative examples were cut into 20 mm squares to prepare sample plates (15 mm squares for the reference aluminum substrate). These were placed on the top plate of an AS ONE digital hot plate ND-1A and heated to 300°C. Next, Ishizaki Electric Mfg.'s resin-cored lead-free solder SURE3AG (1.6 mm diameter) was cut into approximately 2 mm pieces with nippers, and the resulting solder pieces were placed on the sample plate on the digital hot plate and completely melted. The sample plate was then gently removed from the digital hot plate and air-cooled to solidify the solder.

[0080] The contact angle of the solder solidified on each test plate was measured using the θ / 2 method with a Kyowa Interface Science automatic contact angle meter DMo-602. The average contact angle of three points on the same test plate solidified at different locations was calculated. An average contact angle of less than 50° was considered a pass, and an average contact angle of 50° or more was considered a fail. Figure 4(a) shows a photograph of an example of the solder wettability test. Figure 4(b) is an enlarged photograph showing the actual solidified solder.

[0081] <8. Discharge volume> The amount of wastewater generated during the manufacturing process of the plated members according to the examples and comparative examples was evaluated as follows. First, in producing a plated member, the wastewater generated by washing with water was stored in a resin tank, and the amount of wastewater was measured using the scale on the tank. The amount of wastewater measured in each example and comparative example was divided by the amount of wastewater in a conventional double zincate process (Comparative Example 3) for plating an aluminum base material to obtain a wastewater amount ratio. If this wastewater amount ratio was less than 0.5 (less than half that of the double zincate process), the process was deemed to be a drainageless plating process and was judged to pass, and if it was 0.5 or more, the process was judged to fail.

[0082] <9. Oxygen intensity ratio at the interface between aluminum member and nickel plating film> To investigate the factors that affect the differences in wettability of aluminum substrates, elemental profiles of cross sections of plated parts were measured using scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). First, each plated member on which a nickel plating film was formed in the examples and comparative examples was attached to a cross-section polisher IB-09020CP manufactured by JEOL Ltd., and cut by irradiating it with an argon ion beam to prepare a cross-sectional sample for examining the thickness direction.

[0083] The resulting cross-sectional samples were then observed using a Schottky field emission scanning electron microscope (FE-SEM JSM-7200F, manufactured by JEOL Ltd.). EDX analysis of the cross-section was performed at an acceleration voltage of 15 kV to examine the elemental distribution. The point where the Al and Ni element profiles intersect was defined as the Al / Ni interface. The ratio (oxygen intensity ratio) [(ii) / (i)] of the average oxygen intensity (i) in the flat Ni intensity range corresponding to the nickel plating film to the maximum oxygen intensity (ii) detected at the Al / Ni interface was calculated. If this oxygen intensity ratio [(ii) / (i)] was 1.5 or greater, it was determined that an oxygen-containing film forming a hydrophilic primer layer was present at the interface. If it was less than 1.5, it was determined that an oxygen-containing film forming a hydrophilic primer layer was not present at the interface. In the following examples and comparative examples, the oxygen-containing film present at the interface is believed to be due to the presence of a hydrated aluminum oxide film formed simultaneously with the roughening treatment by the surface modification process using laser light irradiation. Alternatively, in the following examples and comparative examples, the oxygen-containing film present at the interface is thought to be due to the presence of an oxide film containing aluminum oxide that is formed in place of the hydrated oxide film formed by laser light irradiation, which is removed by the phosphochromate treatment. As described above, it is presumed that the presence of this hydrated oxide film or oxide film allows the treatment solution used in the catalyst application step to wet and spread evenly over the surface of the aluminum base material, improving the uniformity of the plating.

[0084] 5 and 6 show the measurement of the oxygen intensity ratio at this interface in Example 1. Fig. 5 is an SEM photograph of a cross-sectional sample of the plated member of Example 1, in which the element distribution was examined along the line analysis locus (white dashed line) shown in the center. Fig. 6 shows the element profiles of oxygen (O), aluminum (Al), and nickel (Ni) used to determine the oxygen intensity ratio [(ii) / (i)].

[0085] 10. SEM Observation of Aluminum Substrate / Measurement of Hydrous Oxide Film Thickness To confirm the presence of hydrated oxides on the surface of aluminum substrates that had been surface-modified by laser irradiation, the aluminum substrates were observed using SEM after laser irradiation. Furthermore, to confirm the presence of an oxygen-containing film on the surface of aluminum substrates that had been subjected to a phosphochromate treatment after laser irradiation, the aluminum substrates were observed using SEM after the phosphochromate treatment. A field-emission scanning electron microscope (FE-SEM ULTRA-Plus, manufactured by Carl Zeiss) was used for the observations, and secondary electron images of the surface were obtained at an accelerating voltage of 3 kV. SEM-EDX analysis of the surface was also performed.

[0086] Furthermore, regarding the thickness of the hydrated oxide film, the film thickness of the layer consisting of the hydrated oxide film sandwiched between the aluminum substrate and the nickel plating film in a cross-sectional SEM photograph showing the interface between the aluminum member and the nickel plating film was measured at 10 points, including the thickest and thinnest points, and the average value was calculated.

[0087] <11. Plating area ratio> A plated member representing a standard test specimen was produced in the same manner as in Example 1, except that the aluminum substrate was a 10 mm thick aluminum alloy 1070-O cut into a 100 mm square. Laser light was irradiated onto the aluminum substrate in a roughening treatment area measuring 80 × 100 mm, which corresponds to 80% of the area on one side of the aluminum substrate. A sample measuring 20 × 20 mm was cut from the target plating area of ​​the standard test specimen. The entire surface of the plated member representing the standard test specimen was observed using an SEM at 100x magnification to confirm that a plating film had been formed over the entire surface (100%) of the roughened and catalyzed target plating area. A field-emission scanning electron microscope (FE-SEM ULTRA-Plus, manufactured by Carl Zeiss) was used for observation. Surface images of the standard test specimen were obtained by photographing the target plating area on the surface of the standard test specimen after cutting the sample with a digital camera. Image analysis of the surface image of the standard test specimen was performed using ImageJ. For image analysis, select Image → Adjust → Color Threshold to display the Threshold Color screen, and adjust the bars of the Red, Green, and Blue graphs to obtain an RGB range that selects the entire area of ​​the standard test sample. The plating target area on the surface of the plated member prepared in the example was photographed under the same photographing conditions as the standard test piece to obtain an image of the example. Image analysis was performed on the surface image of this example, and the area ratio was calculated by extracting the area included in the RGB range obtained by image analysis of the surface image of the standard test piece. Those with a plating area ratio of 85% or more were judged as passing (◯), and those with a plating area ratio of less than 85% were judged as failing (×).

[0088] [Example 1] <Surface modification process> Aluminum alloy 6101-T6 with a thickness of 0.6 mm was cut into 50 mm square pieces to prepare aluminum substrates. This aluminum substrate was subjected to surface modification by irradiating the surface of one side of the substrate with laser light using a Keyence laser marker MD-F5200. The main specifications of this laser marker are as follows. In each example and comparative example, laser light was irradiated onto a 25 × 50 mm roughening treatment area covering almost the entire surface of one side of the aluminum substrate using the five irradiation methods shown in Table 1. Laser type: Yb (ytterbium-doped fiber laser) Wavelength: 1090nm Output: 50W Pulse frequency: 60kHz

[0089] [Table 1]

[0090] The sweep modes in Table 1 are as described in the Keyence Marking Builder 3 user's manual (p. 35). The "crossing" here refers to moving the laser beam in one direction (left to right) while irradiating it, then moving it in the opposite direction (right to left) at a specified interval (pitch) (shifting it upward or downward) while irradiating it. This process is repeated until the laser beam irradiation trajectories are aligned at a specified interval within the roughening treatment area. If this is irradiation in the x direction, then the laser beam is moved alternately (up to down) and then downward to up) while irradiating it at the same interval, forming an irradiation trajectory in the y direction that intersects (is perpendicular to) the irradiation trajectory of the laser beam in the x direction.

[0091] One of the "diagonal lines" indicates that the laser beam is irradiated in one direction, moving from left to right (or right to left) at a specified interval, so that the laser beam irradiation trajectory is aligned only in the x direction within the roughening treatment area. For example, "Cross 3600" indicates a sweep speed of 3600 mm / s. Furthermore, "Cross 3600 Strong" indicates that the laser power (%) is increased compared to other irradiation methods. Note that "defocus" in Table 1 refers to adjusting the spot diameter by shifting the focus.

[0092] In this Example 1, the surface of an aluminum substrate was modified using the laser beam irradiation method "Crossing 3600" as shown in Table 2. As described above, the surface was roughened and reacted with moisture in the air to form a hydrated oxide film on the surface of the aluminum substrate, forming a hydrophilic primer layer. The aluminum substrate thus formed with the hydrophilic primer layer was measured for surface roughness Rz, roughened surface area ratio, and substrate wettability using the methods described above. The results are shown in Table 2.

[0093] <Catalyst application step> Next, a 0.25 mol / L copper acetate aqueous solution was applied to the aluminum substrate with the hydrophilic primer layer by immersion, so as to include the area to be roughened. After air-drying at room temperature, the aluminum substrate was placed in an electric furnace maintained at 300°C, and the copper acetate attached to the surface of the aluminum substrate was baked in the air to convert it to copper oxide, thereby forming a catalytic layer that would serve as a plating catalyst. In Example 1, the coating weight of the catalytic layer was 1.0 mg / m 2 It was.

[0094] <Plating process> The aluminum member having the hydrophilic primer layer and catalyst layer formed on the surface of the aluminum base as described above was subjected to a plating treatment to form a nickel plating film as follows. First, the remaining portion of one surface of the aluminum member on which the hydrophilic primer layer and catalyst layer were formed and the back surface were masked with PTFE (polytetrafluoroethylene) tape so that a 25 mm x 50 mm plating area was exposed.

[0095] Next, an aqueous solution containing 450 g / L of nickel sulfamate tetrahydrate, 10 g / L of nickel chloride hexahydrate, and 35 g / L of boric acid, prepared by adding an appropriate amount of sulfamic acid to make the pH 4.0 to 4.5, was circulated in an acrylic tank while maintaining the temperature at 40°C, and the aluminum member masked above was used as the cathode and Sumitomo SK Nickel manufactured by Yamamoto Plating Testing Instruments was used as the anode, with a current density of 2.8 A / dm 2 After the current was turned off, the masked aluminum member was removed and rinsed with running ion-exchanged water for 30 seconds, after which it was dried with a hand dryer, forming a Ni plating film with a thickness of approximately 3 μm on the area to be plated.

[0096] For the plated member according to Example 1, in which a nickel plating film was formed on an aluminum member as described above, the plating uniformity, plating adhesion, and solder wettability were evaluated by the methods described above, and the oxygen intensity ratio at the interface between the aluminum member and the nickel plating film was measured. The amount of wastewater generated when obtaining the plated member in Example 1 was also compared with the amount of wastewater generated in the double zincate process of Comparative Example 3, which will be described later, to determine the wastewater volume ratio. The results are summarized in Table 2.

[0097] [Table 2]

[0098] [Example 2] Instead of the copper oxide calcination performed in Example 1, a silver nanoparticle ink containing silver nanoparticles was applied to the surface of the aluminum substrate irradiated with laser light using a Mitsubishi Paper Mills Circuitry Marker marker pen, and the ink was allowed to dry naturally to form a catalyst layer containing silver nanoparticles as a plating catalyst. In Example 2, the weight of the catalyst layer was 0.9 mg / m 2 A plated member according to Example 2 was produced in the same manner as in Example 1, except for this catalyst application step. Various evaluation results are shown in Table 2.

[0099] [Example 3] Instead of the copper oxide calcination performed in Example 1, platinum was sputtered for 3 minutes under vacuum on the surface of the aluminum substrate irradiated with laser light using a Hitachi ion sputtering device E102 to form a catalyst layer using platinum as a plating catalyst. In Example 3, the coating weight of the catalyst layer was 0.2 mg / m 2 A plated member according to Example 2 was produced in the same manner as in Example 1, except for this catalyst application step. Various evaluation results are shown in Table 2.

[0100] [Examples 4 and 5] Plated members according to Examples 4 and 5 were produced in the same manner as in Example 1, except that the laser light irradiation method in the surface modification step was changed from "intersection 3600" employed in Example 1 to "diagonal line 2700" (Example 4) and "intersection 4500" (Example 5). Various evaluation results are shown in Table 2.

[0101] [Example 6] In the catalyst application step, instead of the copper oxide calcination step performed in Example 1, a silver nanoparticle ink containing silver nanoparticles was applied to the surface of the aluminum substrate irradiated with laser light using a Mitsubishi Paper Mills Circuitry Marker marker pen. The ink was then allowed to dry naturally to form a catalyst layer using silver nanoparticles as a plating catalyst. In addition, in the plating process, electroless plating was performed by immersing a masked aluminum member in Top Nicoron SDB-LF electroless nickel plating solution prepared by Okuno Pharmaceutical Industries Co., Ltd., at 90°C for 10 minutes. The masked aluminum member was then removed, rinsed with running ion-exchanged water for 30 seconds, and dried with a hand dryer to form a Ni plating film with a thickness of approximately 3 μm on the target area. The plated member of Example 6 was produced in the same manner as in Example 1, except for the above. Various evaluation results are shown in Table 2.

[0102] [Example 7] As in Example 1, the aluminum substrate was irradiated with laser light to roughen the surface, forming a hydrated oxide film on the surface, and then subjected to a phosphochromate treatment. Boiling stones were added to an aqueous phosphochromate solution containing 35 ml / L of phosphoric acid and 20 g / L of chromium (VI) oxide, and the laser-treated substrate was immersed in the boiling solution for 10 minutes to remove the hydrated oxide film from the substrate surface. The substrate was then rinsed with running ion-exchanged water for 30 seconds. The plated member of Example 7 was produced in the same manner as in Example 1, except that the phosphate chromate treatment removed the hydrated oxide film formed by the laser irradiation and instead formed an oxide film containing aluminum oxide, which served as the hydrophilic primer layer. Various evaluation results are shown in Table 2.

[0103] [Example 8] The plated member of Example 8 was produced in the same manner as in Example 1, except that in the catalyst application step, a catalyst solution was used in which a 0.5 mol / L aqueous solution of copper formate, prepared by dissolving copper formate (Fujifilm, manufactured by Wako Pure Chemical Industries, Ltd., trade name: copper(II) formate tetrahydrate, product code: 031-13762) in ion-exchanged water, was added to a 0.1 mol / L aqueous solution of formic acid, and the plated member was left standing in an electric furnace maintained at 200°C. Various evaluation results are shown in Table 2.

[0104] [Comparative Example 1] A plated member according to Comparative Example 1 was produced in the same manner as in Example 1, except that the laser light irradiation method in the surface modification step was changed from "cross 3600" employed in Example 1 to "cross 9000," and that in the catalyst application step, instead of the copper oxide calcination performed in Example 1, platinum was sputtered in vacuum for 3 minutes onto the surface of the aluminum base material irradiated with the laser light using a Hitachi ion sputtering apparatus E102 to form a catalyst layer using platinum as a plating catalyst. Various evaluation results are shown in Table 2.

[0105] Comparative Example 2 A plated member according to Comparative Example 2 was produced in the same manner as in Example 1, except that the surface modification step was not performed (surface roughening was not performed and a hydrophilic primer layer was not formed), and the catalyst application step and plating treatment step were performed. Various evaluation results are shown in Table 2.

[0106] Comparative Example 3 To form a nickel plating film on an aluminum substrate made of 0.6 mm thick aluminum alloy 6101-T6 cut into 50 mm square pieces, a conventional zincate treatment (double zincate process) was performed as a pretreatment. This pretreatment consisted of (i) surface preparation, (ii) etching, (iii) desmutting, (iv) primary zincate, (v) zinc stripping, and (vi) secondary zincate, and after each treatment, the plate was rinsed with running ion-exchanged water for 30 seconds. The details of each treatment (i) to (vi) are as follows:

[0107] (i) The aluminum substrate was immersed in a 20% by mass aqueous solution of nitric acid at room temperature for 3 minutes to condition the surface. (ii) The aluminum substrate after the treatment in (i) above was immersed in a 5 mass % aqueous solution of sodium hydroxide kept at 50° C. for 1 minute to dissolve the oxide film on the surface of the substrate (etching). (iii) The aluminum substrate after the treatment in (ii) above was immersed in a 20% by mass aqueous solution of nitric acid at room temperature for 30 seconds to dissolve and remove smut (residues of compounds of added elements, etc.) that had adhered to the surface of the aluminum substrate in the treatment in (ii) above (desmutting). (iv) The aluminum substrate treated in (iii) above was immersed for 30 seconds in a 33.3% by volume aqueous solution of zincate solution AZ-301-3X manufactured by Uemura Kogyo Co., Ltd., kept at 25°C, to deposit a zinc coating by displacement (primary zincate). (v) The aluminum substrate after the treatment in (iv) above was immersed in a 20% by mass aqueous solution of nitric acid at room temperature for 30 seconds to dissolve and remove the zinc coating (zinc stripping). (vi) The aluminum substrate treated in (v) above was immersed for 30 seconds in the same aqueous zincate solution as in the treatment in (iv) above, and a finer and more uniform zinc coating than that in (iv) above was deposited by displacement (secondary zincate).

[0108] In the double zincate process used here, the zinc particles in the zinc film formed by the primary zincate treatment are coarse, and plating on top of this results in plating with poor adhesion. On the other hand, if the plating after the primary zincate treatment is dissolved and removed with nitric acid and then zincate treatment is performed again, a zinc film composed of fine and uniform zinc particles is formed, and it is known that plating on top of this results in plating with excellent adhesion (Reference: Kawashima, Surface Technology, Vol. 64, No. 12, p. 645, "Zincate Treatment of Aluminum" (2013)).

[0109] The aluminum substrate that had been subjected to the above treatments (i) to (vi) and rinsed with running water after each treatment was subjected to the same plating treatment steps as in Example 1, to obtain a plated member according to Comparative Example 3 in which a Ni plating film with a thickness of about 3 μm was formed in the area to be plated. Various evaluation results are shown in Table 2.

[0110] Comparative Example 4 A plated member according to Comparative Example 4 was produced in the same manner as in Example 1, except that after the surface modification step, the plating step was carried out without including the catalyst application step (without forming a catalyst layer). Various evaluation results are shown in Table 2.

[0111] [Comparative Examples 5 and 6] Plated members according to Comparative Examples 5 and 6 were produced in the same manner as in Example 1, except that the laser light irradiation method in the surface modification step was changed from "intersection 3600" employed in Example 1 to "intersection over 3600" (Comparative Example 5) and "intersection 9000" (Comparative Example 6). Various evaluation results are shown in Table 2.

[0112] Comparative Example 7 Instead of the surface modification process using laser light irradiation, the aluminum substrate was matted as follows. Specifically, Japan CB Chemical's Chemical Cleaner 3712 bath additive was diluted to 200 g / L and kept at 45°C in a Teflon (registered trademark) beaker. Aluminum substrates made of 0.6 mm thick aluminum alloy 6101-T6 cut into 50 mm square pieces were immersed in the solution for 5 minutes to dissolve the aluminum substrate surface until it became matte. The aluminum substrate was then removed and rinsed with running ion-exchanged water for 30 seconds.

[0113] The above-mentioned surface treatment does not form a hydrated oxide film on the surface of the aluminum substrate, resulting in insufficient wettability and making it impossible to form a uniform catalyst layer in the catalyst application process. Therefore, the surface-treated aluminum substrate was hydrated by exposing it to water vapor under high pressure. The Espec EHS-411M highly accelerated life tester was used, and the aluminum substrate was placed in the chamber and exposed to water vapor for 30 minutes in saturated mode at 140°C and fully humidified, resulting in surface hydration.

[0114] Next, the same catalyst application step and plating step as in Example 1 were carried out to produce a plated member according to Comparative Example 7. Various evaluation results are shown in Table 2.

[0115] [Comparative Example 8] Instead of the surface modification step of irradiating laser light, the area of ​​the aluminum substrate to be roughened was ground with a stainless steel wire brush, and the abrasion powder was removed with an air blow. Next, as in Comparative Example 7, the aluminum substrate after grinding with the wire brush was hydrated by exposure to water vapor under high pressure. Next, the same catalyst application step and plating step as in Example 1 were carried out to produce a plated member according to Comparative Example 8. Various evaluation results are shown in Table 2.

[0116] [Reference example] For comparison, aluminum alloy 6101-T6 with a thickness of 0.6 mm was cut into 50 mm square pieces and subjected to various evaluations as a reference example without undergoing the surface modification process, catalyst application process, or plating process. The results are shown in Table 2.

[0117] [Test example] In the surface modification process in which laser light is irradiated, the laser power was varied between 30 and 80% and the sweep speed was varied between 300 and 9000 mm / s to prepare a number of aluminum substrates with adjusted degrees of surface modification, and test plated members were manufactured under the same conditions as in Example 3 except for the above. The plating adhesion test described above was performed on each of the obtained test plated members, and the relationship between the roughened area ratio of the aluminum substrate and the unpeeled area ratio of the plating was investigated. The results are shown in the graph in Figure 7. When the unpeeled area ratio is used as an index of plating adhesion, it was found that there is a positive correlation between the roughened area ratio and plating adhesion. In particular, when the roughened area ratio was 80% or more, the unpeeled area ratio was 100%.

[0118] [Example 11] <Surface modification process> The aluminum substrate was a 10 mm thick aluminum alloy 1070-O cut into a 100 mm square. Surface modification was performed by irradiating the aluminum substrate with laser light under the same "3600° intersection" conditions as in Example 1, except that the laser light was irradiated to a roughening treatment area of ​​80 × 100 mm, which corresponds to 80% of the area on one side of the aluminum substrate. The roughened surface area ratio of the aluminum substrate with the hydrophilic primer layer formed thereon was measured using the method described above. The results are shown in Table 3.

[0119] [Table 3]

[0120] <Catalyst application step> A suspension (zinc oxide ink) containing 15 wt% zinc oxide (ZnO) (Wako Pure Chemical Industries, Ltd., product name: Zinc Oxide, 0.02 μm, product code: 260-01261) was prepared by adding 15 g of zinc oxide to 100 g of ethanol and sonicating for 30 minutes using an ultrasonic cleaner. 2.0 mL of zinc oxide ink was applied to the entire surface of the aluminum substrate with a hydrophilic primer layer by dripping it with a dropper over the roughening treatment area. A 1 mm-thick silicone sheet (product name: Silicone Rubber Sheet, AS ONE product number: 6-611-02) was cut to a width of 150 mm and a length of 50 mm. The cut silicone sheet was attached to the bar of a desktop coater (Hosen Co., Ltd., product name: Mini Desktop Coater, product number: MC30) so that the length of the bar matched the width of the cut silicone sheet. The zinc oxide ink was dropped onto the surface of the aluminum substrate, and the longitudinal edge of the silicone sheet was brought into contact with it. The bar of a desktop coater was moved at a constant scanning speed of 15 mm / s, and the silicone sheet was used to sweep the surface, removing excess ink. The sheet was then allowed to dry naturally at room temperature, forming a catalyst layer that would serve as a plating catalyst.

[0121] <Plating process> A plated member according to Example 11 was produced by carrying out a plating treatment step under the same conditions as in Example 1. The results of the various evaluations are shown in Table 3.

[0122] [Examples 12 to 19] A plated member according to Example 12 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 15 mass %, the ink droplet amount was 1.5 ml, and the scanning speed of the silicone sheet was 15 mm / s. A plated member according to Example 13 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 8 mass %, the ink droplet amount was 1.0 ml, and the scanning speed of the silicone sheet was 15 mm / s. A plated member according to Example 14 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 10 mass %, the ink droplet amount was 1.0 ml, and the scanning speed of the silicone sheet was 15 mm / s. A plated member according to Example 15 was produced in the same manner as in Example 1, except that the zinc oxide concentration of the zinc oxide ink was 15 mass %, the ink droplet amount was 2.0 ml, and the scanning speed of the silicone sheet was 15 mm / s. A plated member according to Example 16 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 15 mass %, the ink droplet amount was 2.0 ml, and the scanning speed of the silicone sheet was 10 mm / s. A plated member according to Example 17 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 15 mass %, the ink droplet amount was 1.5 ml, and the scanning speed of the silicone sheet was 10 mm / s. A plated member according to Example 18 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 5 mass %, the ink droplet amount was 1.0 ml, and the scanning speed of the silicone sheet was 15 mm / s. A plated member according to Example 19 was produced in the same manner as in Example 11, except that the zinc oxide concentration of the zinc oxide ink was 15 mass %, the ink droplet amount was 2.0 ml, and the scanning speed of the silicone sheet was 2.5 mm / s. The various evaluation results are shown in Table 3.

[0123] [Consider] Regarding the plated members obtained in these Examples and Comparative Examples, first, FIG. 8 shows SEM photographs of the surface of the aluminum substrate irradiated with laser light in Example 1. In FIGS. 8(a) and 8(b), the appearance of spots formed by laser light irradiation can be confirmed. Furthermore, in FIG. 8(c), which is an enlarged view of a portion thereof, the formation of fine whisker-like irregularities on the order of several tens of nanometers, which are likely hydrated oxides, can be confirmed on the aluminum substrate irradiated with laser light. Furthermore, FIG. 9 shows the results of EDX analysis of this aluminum substrate. Since a strong oxygen peak was detected, it is inferred that hydrated oxides of aluminum were formed on the aluminum substrate roughened by laser light irradiation.

[0124] FIG. 10 is an example of a cross-sectional SEM photograph showing the interface between an aluminum member and a nickel plating film. This photograph is of the plated member of Example 3, and FIG. 10(b) is an enlarged view of a portion (encircled by a dashed line) of the interface shown in FIG. 10(a). FIG. 10(b) confirms the presence of a hydrated oxide film formed at the interface with the nickel plating film when the aluminum substrate was roughened by laser irradiation. The hydrated oxide film has irregularities up to 200 nm thick, and although the irregularities at the thinnest points are only a few tens of nanometers thick, it is clear that the nickel plating film has been formed (filled) even in the thinnest points. In other words, at the interface between the aluminum member and the nickel plating film, electrical and thermal conductivity is maintained between the aluminum substrate side and the nickel plating film side.

[0125] Furthermore, regarding the thickness of the hydrated oxide film shown in FIG. 10(b), the layer consisting of the hydrated oxide film sandwiched between the aluminum base material and the nickel plating film in the cross-sectional SEM photograph shown in FIG. 11, which shows the interface between the aluminum member and the nickel plating film, was measured for the film thickness at 10 points (points 1 to 10), including the thickest and thinnest points, and the results are shown in Table 4, with the average value being 91.87 nm.

[0126] [Table 4]

[0127] Furthermore, Fig. 12 shows SEM photographs of the surface of an aluminum substrate that was irradiated with laser light and then subjected to a chromic phosphate treatment in Example 7. In Fig. 12(a), the appearance of spots that had been subjected to the chromic phosphate treatment was confirmed. In Fig. 12(b), which is an enlarged view of a portion of Fig. 12(a), it was confirmed that the fine whisker-like irregularities that were likely hydrated oxides and that were confirmed in Fig. 8(c) on the aluminum substrate that had been subjected to the chromic phosphate treatment had been removed, resulting in a smooth surface.

[0128] The plated members obtained in the examples and comparative examples were evaluated for various properties as follows. First, in Comparative Examples 1 and 6, the roughened area ratio of the aluminum substrate was insufficient, possibly because the sweep speed during laser irradiation in the surface modification step was too fast. As a result, even though the substrate had good wettability and the plating film was formed uniformly, the nickel plating film did not have sufficient adhesion, resulting in plating peeling.

[0129] In Comparative Example 2, the surface modification process was not performed, so the aluminum substrate was not roughened and no hydrated oxide film was present. Therefore, the aluminum substrate had poor wettability, and the catalyst solution did not spread well during the subsequent catalyst application process. This resulted in the formation of a uniform nickel plating film and poor adhesion, leading to plating peeling. Since uniform plating was not achieved, a solder wettability test was not performed.

[0130] In addition, in Comparative Example 3, the nickel plating film formed on the aluminum substrate by the double zincate treatment passed the test in terms of uniformity, adhesion, and solder wettability. However, since the amount of wastewater generated in the manufacturing process was large, the result was judged to be unacceptable as a drainage-free plating process. In Comparative Example 4, since no catalyst was applied and no plating catalyst was present, hydrogen was mainly generated during the plating process, and almost no nickel plating film was formed. Therefore, no evaluations were performed after the plating adhesion test.

[0131] On the other hand, in Comparative Example 5, the nickel plating film was not formed uniformly. This is thought to be because the surface was excessively roughened in the surface modification process by laser light irradiation, which increased the surface roughness Rz of the aluminum base material and the surface area, and the catalyst solution did not spread sufficiently in the catalyst application process. Therefore, evaluations after the plating adhesion test were not performed.

[0132] In Comparative Examples 7 and 8, instead of irradiating the aluminum substrate with laser light, a matte finish (Comparative Example 7) and wire brush grinding (Comparative Example 8) were performed, followed by hydration. However, when the surface roughness Rz was too small (Comparative Example 7) or too large (Comparative Example 8), the nickel plating film was not uniformly formed. Therefore, evaluations after the plating adhesion test were not performed. These results may be due not only to the roughening of the aluminum substrate, but also to the hydrated oxide film that forms simultaneously with the roughening. In Comparative Examples 1, 2, and 6, the nickel plating film was not formed with good adhesion, so cross-sectional SEM-EDX observation of the oxygen intensity ratio was not performed.

[0133] In contrast, in Examples 1 to 8, the amount of wastewater discharged during the manufacturing process was reduced while the wettability of the aluminum members was improved, enabling the manufacture of plated members with excellent nickel plating film uniformity, adhesion, and solder wettability.

[0134] 13 is an example of a cross-sectional SEM photograph showing the interface between an aluminum member and a nickel plating film in a plated member provided with a nickel plating film. This photograph is of the plated member of Example 17. Fig. 14(a) is an example of a cross-sectional SEM photograph showing the interface between an aluminum member and a nickel plating film. Fig. 14(b) is an enlarged view of a portion of the interface shown in Fig. 14(a). These photographs are of the plated member of Example 17. FIG. 13 confirms that a uniform nickel plating film was formed on the aluminum member. From Figure 14(a), it was confirmed that a uniform nickel plating film was formed on the aluminum member. The thickness of the nickel plating film was approximately 2.7 μm. Figure 14(b) confirms that a layer was formed at the interface between the aluminum substrate and the nickel plating film. The thickness of this layer was approximately 120 nm. EDX analysis of this layer detected Zn, confirming that this layer was a catalyst layer containing zinc oxide.

[0135] In all of Examples 11 to 19, a nickel plating film with sufficient adhesion could be formed. However, in Example 18, the plating area ratio was low, possibly due to the low zinc oxide concentration of the zinc oxide ink. This is thought to be because although zinc oxide particles were applied to the entire surface of the aluminum base material, the zinc oxide particles were present in a sparse state on the surface of the aluminum base material, and the catalyst layer was formed in a scattered manner, so that the catalyst layer was not formed to cover the entire area to be plated. In Example 19, the plating area ratio was low, possibly due to the slow scanning speed of the silicone sheet. This is thought to be because the silicone sheet wiped off more zinc oxide ink than necessary from the surface of the aluminum base material, resulting in a shortage of zinc oxide particles being applied to the surface of the aluminum base material.

[0136] As described above, according to the present invention, a plated member having a nickel plating film can be obtained by using an aluminum substrate made of aluminum or an aluminum alloy and by performing all pretreatments for plating, such as roughening the aluminum substrate and applying a plating catalyst, using dry methods. Therefore, compared with conventional methods using zincate treatment, the amount of wastewater generated during water rinsing can be significantly reduced, thereby reducing the effort and cost required for wastewater treatment. Furthermore, the resulting plated member can have an excellent nickel plating film with excellent adhesion, which can promote its use as an aluminum substitute for copper in bus bars, heat sinks, and the like.

Claims

1. A plated member in which a nickel plating film is formed on an aluminum substrate made of aluminum or an aluminum alloy, An aluminum member having, on the surface of the aluminum base, a hydrophilic primer layer including at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrated oxide and an oxide film containing an aluminum oxide, and a catalyst layer including a plating catalyst made of a metal or a metal oxide, in this order; and The nickel plating film is formed on the catalyst layer of the aluminum member, the surface roughness Rz of the aluminum base material on which the hydrophilic primer layer is formed is 2 μm or more and 15 μm or less; A plated member characterized by:

2. the roughened surface area ratio of the aluminum substrate on which the hydrophilic primer layer is formed is 80% or more and 100% or less; The plated member according to claim 1 .

3. The elemental profiles of aluminum, nickel, and oxygen obtained by EDX ray analysis of a cross section of the plated member are as follows: a point where an elemental profile of aluminum and an elemental profile of nickel intersect is defined as an Al / Ni interface between the aluminum member and the nickel plating film; an oxygen intensity ratio, which is a ratio of the maximum oxygen intensity detected at the Al / Ni interface to the average value of the oxygen element profile intensity detected in a flat range of the nickel element profile intensity, is 1.5 or more and 50 or less; The plated member according to claim 1 .

4. The thickness of the hydrophilic primer layer is 1 nm or more and less than 1 μm. The plated member according to claim 1 .

5. The thickness of the catalyst layer is 2 nm or more and less than 1 μm. The plated member according to claim 1 .

6. The plated member according to claim 1, The thickness of the nickel plating film is 1 μm or more and 1 mm or less, the nickel plating film is formed only on one or more portions of the aluminum base material, and is not formed on the remaining portions; Plated material used as a busbar.

7. The metal is at least one metal selected from the group consisting of precious metals including gold, silver, and copper, platinum group metals including platinum and palladium, zinc, ruthenium, and rhodium. The plated member according to any one of claims 1 to 6.

8. The metal is zinc. The plated member according to any one of claims 1 to 6.

9. A method for producing a plated member in which a nickel plating film is formed on an aluminum substrate made of aluminum or an aluminum alloy, comprising: a surface modification step of irradiating a surface of the aluminum base with laser light to roughen the surface of the aluminum base and form, on the surface of the aluminum base, a hydrophilic primer layer including at least one film selected from the group consisting of a hydrated oxide film containing an aluminum hydrated oxide and an oxide film containing an aluminum oxide; a catalyst application step of applying a plating catalyst made of a metal or a metal oxide to the surface of the aluminum base on which the hydrophilic primer layer has been formed, to form a catalyst layer containing the plating catalyst on the surface of the aluminum base; a plating process step of performing a nickel plating process on the aluminum member having the hydrophilic primer layer and the catalytic layer formed on the surface of the aluminum base to form the nickel plating film on the catalytic layer of the aluminum member, The surface roughness Rz of the aluminum substrate on which the hydrophilic primer layer is formed in the surface modification step is 2 μm or more and 15 μm or less. A method for producing a plated member, comprising:

10. The catalyst application step includes: a coating step of coating the aluminum substrate with a catalyst solution or catalyst suspension containing a metal compound of the metal to adhere the metal compound to the aluminum substrate; and a calcination step of calcining the aluminum base to which the metal compound is attached to obtain an oxide of the metal from the metal compound on the surface of the aluminum base, thereby forming the plating catalyst. The method for producing a plated member according to claim 9 .

11. the metal compound is an organic acid salt of the metal; The method for producing a plated member according to claim 10.

12. In the firing step, the firing temperature is 180°C or higher and 500°C or lower. The method for producing a plated member according to claim 10.

13. The catalyst application step includes: a coating step of coating the aluminum substrate with a catalyst solution or catalyst suspension containing metal nanoparticles made of the metal or an oxide of the metal, thereby adhering the metal nanoparticles to the aluminum substrate; a drying step of drying the aluminum base material to which the metal nanoparticles are attached to form the plating catalyst by the metal nanoparticles. The method for producing a plated member according to claim 9 .

14. The catalyst application step includes: a sputtering step of forming the plating catalyst by sputtering the metal to form a metal coating film made of the metal on the aluminum base material, The method for producing a plated member according to claim 9 .

15. In the plating treatment step, the nickel plating treatment is electroplating. The method for producing a plated member according to claim 9 .

16. The metal is a metal that catalyzes the reduction reaction of nickel, among potentially noble metals that are insoluble in a nickel plating bath. The method for producing a plated member according to claim 9 .

17. The metal is at least one metal selected from the group consisting of precious metals including gold, silver, and copper, platinum group metals including platinum and palladium, zinc, ruthenium, and rhodium. The method for producing a plated member according to any one of claims 9 to 16.

18. The metal is zinc. The method for producing a plated member according to any one of claims 9 to 16.

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