Manufacturing method for plated products

Abstract

A base material 1 is a non-electroconductive member and is made of, e.g., a carbon composite material or a resin such as engineering plastic or super engineering plastic. First, an electroless plating layer 3 made of, e.g., Ni is formed on the surface of the base material 1. Next, an aluminum plating layer 5 is formed on the surface of the electroless plating layer 3 by electrolytic plating. An adhesion-improving layer 9 made of, e.g., Cu may be formed between the electroless plating layer 3 and the aluminum plating layer 5.

Description

Plated products and their manufacturing methods

[0001] The present invention relates to a plated product in which the surface of a substrate is plated, and a method for manufacturing the same.

[0002] Carbon fiber composite materials, for example, are used as lightweight and high-strength materials. Carbon fiber composite materials are made by impregnating carbon fiber sheets with resin and curing them. Because they are lightweight and strong, they are used in a variety of fields. However, carbon fiber composite materials are generally black with a carbon fiber weave pattern, and therefore are not necessarily highly aesthetically pleasing.

[0003] In order to enhance the design of components using such resins as base materials, methods have been proposed, such as coating the resin surface, as well as forming a plating layer that can impart a metallic luster (for example, Patent Document 1).

[0004] JP 2023-16073 A

[0005] Such plating layers are generally produced by applying electroless plating to the resin surface or by applying electrolytic chrome plating to that surface, both of which produce a metallic appearance, but they do not necessarily achieve a high-quality texture or sufficient design.

[0006] The present invention has been made in view of such problems, and aims to provide plated products and the like that can achieve high designability.

[0007] In order to achieve the above-mentioned object, a first invention is a plated product comprising a non-conductive substrate, an electroless plating layer formed on the surface of the substrate, and an aluminum plating layer laminated on the electroless plating layer.

[0008] The electroless plated layer may be a Ni plated layer, and a Cu plated layer may be provided between the Ni plated layer and the aluminum plated layer.

[0009] It is desirable that the Ni plating layer be harder than the Cu plating layer and the aluminum plating layer, and that the Cu plating layer be harder than the aluminum plating layer.

[0010] It is also preferable that the Ni plating layer has a thickness of 0.1 μm to 5 μm and the Cu plating layer has a thickness of 1 μm to 30 μm. Alternatively, the Ni plating layer may have a thickness of 0.1 μm to 1 μm and the Cu plating layer may have a thickness of 1 μm to 30 μm, with the Ni plating layer being thinner than the Cu plating layer.

[0011] The substrate is preferably a fiber-reinforced plastic.

[0012] Furthermore, it is desirable that an anodized film be formed on the surface of the aluminum plating layer, and that the thickness of the aluminum plating layer including the thickness of the anodized film be 20 μm to 100 μm.

[0013] A second invention is a method for manufacturing a plated product according to the first invention, comprising the steps of: forming an electroless Ni plating layer on a non-conductive base material; forming a Cu plating layer on the surface of the Ni plating layer; and laminating an aluminum plating layer on the surface of the Cu plating layer by electrolytic plating.

[0014] The method may further include a step of anodizing the surface of the aluminum plating layer.

[0015] The electrolytic solution used to form the aluminum plating layer contains dialkyl sulfone, aluminum halide, ammonium halide, hydrogen halide salt of primary amine, hydrogen halide salt of secondary amine, hydrogen halide salt of tertiary amine, and a compound represented by the general formula: R １ R ２ R ３ R ４ N.X. (R １ ~R ４ and X represents the same or different alkyl groups, and X represents a counter anion to the quaternary ammonium cation).

[0016] An oxide film removing step of removing an oxide film from the Ni plating layer may be provided between the step of forming the Ni plating layer and the step of forming the Cu plating layer.

[0017] In the step of forming the aluminum plating layer, the member on which the Cu plating layer has been formed may be immersed in the non-aqueous electrolytic solution and then electrolysis may be performed after a holding time of 3 seconds or more.

[0018] According to the present invention, it is possible to provide plated products and the like that can achieve high designability.

[0019] 1 is a conceptual diagram showing the manufacturing process of plated products 10 and 10a; 2 is a conceptual diagram showing the manufacturing process of plated products 10 and 10a; 3 is a conceptual diagram showing the manufacturing process of plated products 10 and 10a; 4 is a conceptual diagram showing the manufacturing process of plated product 10a; and 5 is a conceptual diagram showing plated product 10b. 6 is a photograph of an electrodeposited film on the surface of a cathode electrode (current density 10-80 mA / cm ２ ) Photograph of the electrodeposited film on the cross section of the cathode electrode (current density 10-80 mA / cm ２ ) Photograph of the electrodeposited film on the surface of the cathode electrode (current density 10 mA / cm ２ ) Photograph of the electrodeposited film on the cross section of the cathode electrode (current density 10 mA / cm ２ )

[0020] A plated product according to an embodiment of the present invention comprises a non-conductive substrate, an electroless plating layer formed on the substrate, and an aluminum plating layer laminated on the electroless plating layer. Furthermore, by providing an anodized coating on the aluminum plating layer, even greater design flexibility can be achieved. In this case, the thickness of the aluminum plating layer, including the thickness of the anodized coating, is preferably 20 μm to 100 μm (20 μm to 100 μm; the same applies below). It is preferable that the electroless plating layer is a Ni (nickel) plating layer, and that a Cu (copper) plating layer is provided between the Ni plating layer and the aluminum plating layer. In particular, it is preferable that the Cu plating layer and the Ni plating layer, or the Cu plating layer and the aluminum plating layer, are formed adjacent to each other and in close contact with each other. It is preferable that the Ni plating layer is harder than the Cu plating layer and the aluminum plating layer, and that the Cu plating layer is harder than the aluminum plating layer. The Ni plating layer is preferably 0.1 μm to 5 μm thick, and the Cu plating layer is preferably 1 to 30 μm thick. Alternatively, the Ni plating layer may be 0.1 μm to 1 μm thick, and the Cu plating layer may be 1 μm to 30 μm thick, with the Ni plating layer being thinner than the Cu plating layer. The substrate is preferably a fiber-reinforced plastic.

[0021] In addition, a method for manufacturing a plated product according to an embodiment of the present invention is characterized by comprising the steps of forming an electroless plating layer on a non-conductive substrate and laminating an aluminum plating layer on the electroless plating layer by electrolytic plating, and more preferably further comprising the step of anodizing the surface of the aluminum plating layer. The electrolytic solution used for forming the aluminum plating layer is a solution containing a dialkyl sulfone, an aluminum halide, an ammonium halide, a hydrogen halide salt of a primary amine, a hydrogen halide salt of a secondary amine, a hydrogen halide salt of a tertiary amine, and a compound represented by the general formula: R １ R ２ R ３ R ４ N.X. (R １ ~R４ and X represents the same or different alkyl groups, and X represents a counter anion to the quaternary ammonium cation. An oxide film removing step of removing an oxide film from the Ni plating layer may be provided between the step of forming the Ni plating layer and the step of forming the Cu plating layer. In the step of forming the aluminum plating layer, the member on which the Cu plating layer has been formed may be immersed in the non-aqueous electrolytic solution, and then electrolysis may be performed after a holding time of 3 seconds or more.

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1A to 1D are conceptual diagrams illustrating a manufacturing process for a plated product 10 according to the present invention. In FIG. 1A, the substrate 1 is a non-conductive member, including resin or inorganic materials such as glass and ceramics. Non-conductive resin materials include, for example, polyethylene terephthalate, fiber-reinforced plastics (CFRP or GFRP) made of carbon fiber or glass fiber, and engineering or super-engineering plastics such as polycarbonate, polyimide, and polyphenylene sulfide. While the substrate 1 is shown as a plate, it may have any shape, such as an electronic device housing, mobility components, or outdoor / leisure equipment. Furthermore, if the substrate 1 is a flexible non-conductive resin material, it can be applied to deformable objects and can be used for a variety of applications. On the other hand, when applied to ceramics as an inorganic material, it can impart a metallic texture to ceramics, for example.

[0023] Next, as shown in FIG. 1B , an electroless plating layer 3 is formed on the surface of the substrate 1. While the electroless plating layer 3 is not particularly limited, from the viewpoints of adhesion to the substrate 1 and manufacturability, it is desirable for the electroless plating layer 3 to contain one or more of Cu, Ni, Au (gold), Pd (palladium), Sn (tin), Ag (silver), and Pt (platinum). The electroless plating layer 3 can be formed by a known method. The thickness of the electroless plating layer 3 may be, for example, approximately 0.1 μm to 5 μm. Furthermore, prior to electroless plating, the surface of the substrate 1 may be roughened by polishing, grinding, blasting, etching, or the like. This can improve adhesion between the substrate 1 and the electroless plating layer 3.

[0024] Next, as shown in FIG. 1C , an aluminum plating layer 5 is laminated on the electroless plating layer 3 by electroplating. At this time, it is desirable to remove any oxide film from the surface of the electroless plating layer 3 by pickling or the like, if necessary. The thickness of the aluminum plating layer 5 is desirably at least 3 μm or more. This allows the underlying electroless plating layer 3 to be completely covered so that it is not visible, and also provides functions such as electrical conductivity and thermal conductivity to the surface layer. In this manner, a plated product 10 is manufactured.

[0025] The electrolytic solution used in laminating the aluminum plating layer 5 is not particularly limited, but examples thereof include (1) dialkyl sulfone, (2) aluminum halide, and (3) ammonium halide, hydrogen halide salt of primary amine, hydrogen halide salt of secondary amine, hydrogen halide salt of tertiary amine, and the like, which are represented by the general formula: R １ R ２ R ３ R ４ N.X. (R １ ~R ４ and X represents the same or different alkyl groups, and X represents a counter anion to the quaternary ammonium cation. Use of this electrolytic solution makes it possible to laminate a high-purity aluminum plating layer 5 on the electroless plating layer 3 at a high film formation rate.

[0026] Examples of dialkyl sulfones to be contained in the electrolytic solution include those having an alkyl group with 1 to 6 carbon atoms (which may be linear or branched), such as dimethyl sulfone, diethyl sulfone, dipropyl sulfone, dihexyl sulfone, and methyl ethyl sulfone. From the viewpoints of good electrical conductivity and ease of availability, dimethyl sulfone can be preferably used.

[0027] Examples of aluminum halides include aluminum chloride, aluminum bromide, etc. The aluminum halide is preferably anhydrous.

[0028] Examples of ammonium halides that can be used as the nitrogen-containing compound include ammonium chloride and ammonium bromide. Furthermore, examples of the primary to tertiary amines in the hydrogen halide salts of primary to tertiary amines include those in which the alkyl group has 1 to 6 carbon atoms (either linear or branched), such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, hexylamine, and methylethylamine. Examples of hydrogen halides include hydrogen chloride and hydrogen bromide. General formula: R １ R ２ R ３ R ４ N.X. (R １ ~R ４ are the same or different alkyl groups, and X represents a counter anion to the quaternary ammonium cation), １ ~R ４ Examples of the alkyl group represented by the formula (I) include those having 1 to 6 carbon atoms (which may be linear or branched), such as methyl, ethyl, propyl, and hexyl groups. X may be a halide ion such as a chloride ion, a bromide ion, or an iodide ion, as well as BF ４ － and PF ６ －Examples of the nitrogen-containing compound include tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, and tetraethylammonium boron tetrafluoride. A suitable nitrogen-containing compound is a tertiary amine hydrochloride, such as trimethylamine hydrochloride, which facilitates the formation of a high-purity aluminum plating layer 5 at a high film-forming rate.

[0029] The blending ratio of dialkyl sulfone, aluminum halide, and nitrogen-containing compound is preferably 1.5 to 5.0 moles, more preferably 2.0 to 4.2 moles, of aluminum halide per 10 moles of dialkyl sulfone. The blending ratio of nitrogen-containing compound is preferably 0.01 to 2.0 moles, more preferably 0.05 to 1.5 moles. If the blending amount of aluminum halide per 10 moles of dialkyl sulfone is less than 1.5 moles, the aluminum plating layer 5 may be darkened (a phenomenon known as "burning") or the film formation efficiency may be reduced. On the other hand, if the blending amount of aluminum halide is more than 5.0 moles per 10 moles of dialkyl sulfone, the solution resistance of the electrolyte may become too high, causing the electrolyte to generate heat and decompose. Furthermore, if the blending amount of nitrogen-containing compound is less than 0.01 moles per 10 moles of dialkyl sulfone, the effects of blending, i.e., the improved electrical conductivity of the electrolyte, which allows plating at high current densities, resulting in an increased film formation rate, and the improved purity and ductility of the aluminum plating layer 5, may be difficult to achieve. On the other hand, if the amount of the nitrogen-containing compound exceeds 2.0 moles per 10 moles of the dialkyl sulfone, the composition of the electrolyte solution will change substantially, and aluminum may not be deposited.

[0030] The plating process using the above-mentioned electrolytic solution is carried out, for example, at an electrolytic solution temperature of 80°C to 110°C and an applied current density of 0.5 mA / cm ２ ~200mA / cm ２Under these conditions, a voltage is applied so that the substrate 1 having the electroless plating layer 3 serves as the cathode (anode material can be, for example, aluminum). The lower limit of the temperature of the electrolyte should be determined taking into account the freezing point of the electrolyte, and is preferably 85°C, more preferably 95°C (below the freezing point of the electrolyte, the plating solution solidifies, making plating no longer possible). On the other hand, by setting the upper limit of the temperature of the electrolyte to 110°C, deformation of the substrate 1 can be suppressed. If the temperature of the electrolyte exceeds 110°C, the reaction between the aluminum plating layer 5 and the electrolyte becomes more active, and a large number of impurities may be incorporated into the aluminum plating layer 5, reducing its purity. In addition, if the applied current density is 0.5 mA / cm ２ On the other hand, if the applied current density is less than 200 mA / cm, the film formation efficiency may decrease. ２ If the current exceeds 100 mA / cm, the decomposition of the nitrogen-containing compound may cause a problem that the plating process cannot be performed stably or that a high-purity aluminum plating layer 5 cannot be obtained. ２ The advantage of this method is that stable plating is possible even when a current density above this level is applied, thereby improving the film formation rate. The plating time depends on the desired film thickness of the aluminum plating layer 5, the temperature of the electrolytic solution, the applied current density, and other factors, but is usually 1 to 90 minutes. In consideration of production efficiency, a time of 1 to 60 minutes is desirable.

[0031] Next, if necessary, the surface of the aluminum plating layer 5 is polished to smooth the surface of the aluminum plating layer 5, thereby enhancing the metallic luster.

[0032] By reducing the crystal grain size of the aluminum plating layer 5, the surface roughness of the aluminum plating layer 5 after plating can be reduced. Therefore, by intentionally including impurities such as Cu or Si (silicon) in the plating components of the aluminum plating layer 5, the crystal grains can be made finer and the surface roughness can be reduced. For example, by ionizing a certain amount of Cu or the like in the electrolytic solution during plating, the purity of the aluminum plating layer 5 can be intentionally reduced and the crystal grains can be made finer. For example, an aluminum alloy containing 0.1% to 24% by mass of Si, 0.1% to 5% by mass of Cu, and 0.15% to 1.8% by mass of Fe (iron) can be used as the anode electrode for the aluminum plating layer. The anode electrode can be obtained by, for example, casting used AC2A alloy (JIS H 5202) into an electrode shape. Furthermore, the anode current density during plating can be set to 40 mA / cm. ２ ~200mA / cm ２ By doing so, Cu can be contained in the electrodeposited film to be formed.

[0033] Furthermore, as shown in FIG. 1D , the surface of the aluminum plating layer 5 may be anodized to form an anodic oxide coating 7 on the surface of the aluminum plating layer 5. In this manner, a plated product 10a having an anodic oxide coating is manufactured. The anodizing method is not particularly limited and can be performed by a known method. The anodizing conditions are appropriately set depending on the desired thickness of the anodic oxide coating 7, the anodizing solution used, and other factors. If necessary, the aluminum plating layer 5 may be divided into multiple sections, and each section may be anodized under different conditions. During the anodizing process, a color tone may be imparted to the anodic oxide coating 7 by natural color development, or by coloring (so-called color anodizing).

[0034] The total thickness of the aluminum plating layer 5 (including the thickness of the anodic oxide coating 7) is preferably 20 μm to 100 μm. The anodic oxide coating 7 is formed on the surface side of the aluminum plating layer 5 in a direction that increases the thickness, and is formed so as to erode a part of the original aluminum plating layer 5. In other words, when electrolytic plating is performed, the aluminum plating layer 5 is formed to a thickness that takes into account the change in thickness due to the anodic oxide coating 7 formed during the anodizing treatment.

[0035] In order to improve the adhesion between the substrate 1 and the electroless plated layer 3, an adhesion improving layer may be further formed between the aluminum plated layer 5 and the electroless plated layer 3. For example, as in the plated product 10b shown in FIG. 2 , an adhesion improving layer 9 may be provided between the electroless plated layer 3 and the aluminum plated layer 5. In addition, when the electroless plated layer 3 is a Ni plated layer, a Cu electroplated layer may be formed as the adhesion improving layer 9. This Cu plated layer can be formed by a plating method using a known plating solution.

[0036] Here, the adhesion-improving layer 9 is a layer for improving the adhesion between, for example, the substrate 1 and the aluminum plating layer 5. When a Ni plating layer is formed as the electroless plating layer 3, the surface of the Ni plating layer is oxidized by oxygen in the atmosphere. If such an oxide film is formed on the surface of the Ni plating layer and an aluminum plating layer 5 is formed directly on the surface of the Ni plating layer, adhesion may be impaired. For this reason, it is desirable to completely remove the oxide film of the Ni plating layer by pickling or the like before forming the aluminum plating layer 5 on the surface of the Ni plating layer. However, it is difficult to completely remove the Ni oxide film.

[0037] On the other hand, as described above, in order to improve the adhesion between the substrate 1 and the aluminum plating layer 5, a Cu plating layer may be further formed between the aluminum plating layer 5 and the Ni plating layer, which makes it easier to remove the oxide film that is required before forming the aluminum plating layer. That is, it is preferable to form a Cu plating layer between the Ni plating layer and the aluminum plating layer, on which an oxide film that is more fragile than the oxide film formed on the Ni plating layer is formed.

[0038] Furthermore, when forming a Cu plating layer on the surface of a Ni plating layer, even if the oxide film of the Ni plating layer is not completely removed, peeling between Ni and Cu hardly occurs compared to peeling between Ni and aluminum. This is presumably because the adhesion between Ni and Cu is sufficiently high compared to the adhesion between aluminum and other layers. Therefore, when forming a Cu plating layer on the surface of a Ni plating layer, removal of the oxide film of the Ni plating layer may be omitted, or simple pickling or the like may be sufficient compared to when forming an aluminum plating layer on the surface of a Ni plating layer.

[0039] On the other hand, when a Cu plating layer is formed using an aqueous plating solution that uses water as a solvent, a subsequent moisture removal process (e.g., drying) forms an oxide film on the surface of the Cu plating layer. However, even in this case, compared to a Ni oxide film, a Cu oxide film is more easily removed by directly immersing it in a non-aqueous aluminum plating solution, particularly a non-aqueous plating solution containing the above-mentioned dialkyl sulfone, aluminum halide, and nitrogen-containing compound, thereby reducing its impact. This improves adhesion between the aluminum plating layer and the substrate. Therefore, it is preferable to form an aluminum plating layer directly on the surface of the Cu plating layer. In particular, when the substrate is made of flexible polyethylene terephthalate or polyimide, the plated product according to the embodiment of the present invention will be used in a state of flexural deformation. Even in this case, the aluminum plating layer 5 has good adhesion to the Cu plating layer, thereby reducing the occurrence of defects such as peeling.

[0040] In particular, the non-aqueous plating solution containing the dialkyl sulfone, aluminum halide, and nitrogen-containing compound described above contains AlCl ４ ― and Al ２ Cl ７ －This is thought to be because halide aluminum ion species, such as those represented by the following, are present, and these halides decompose and remove the copper oxide film. To ensure the removal of the oxide film from the Cu plating layer before forming the aluminum plating layer, it is desirable to immerse the member on which the Cu plating layer has been formed in a non-aqueous electrolytic solution during the aluminum plating layer formation process, and then apply electrolysis current after a holding time of at least 3 seconds. For example, while current application is generally performed immediately after immersion to shorten cycle time, the effect of the oxide film on the Cu plating layer can be suppressed by holding the electrolytic current for an oxide film removal time after immersion and then starting aluminum electroplating after the holding time for oxide film removal. During the oxide film removal time, the object to be plated may be vibrated or the electrolytic current may be stirred.

[0041] In this case, it is desirable that the Ni plating layer be 0.1 μm to 5 μm and the Cu plating layer be 1 μm to 30 μm. Furthermore, it is more preferable that the Ni plating layer be 0.1 μm to 1 μm and the Cu plating layer be 1 μm to 30 μm, with the Ni plating layer being thinner than the Cu plating layer. If the Ni plating layer is less than 0.1 μm, pinholes and other untreated portions may occur. Furthermore, if the Ni plating layer is more than 1 μm, or even more than 5 μm, it takes a long time to form it by electroless plating. Furthermore, if the Cu plating layer is less than 1 μm, pinholes and other untreated portions may occur, exposing the base layer. Furthermore, if the Cu plating layer is more than 30 μm, the processing time becomes longer, which may reduce productivity.

[0042] Furthermore, as described above, when an oxide film is formed on the Cu plating layer, the oxide film is removed by the electrolyte of the aluminum plating layer, and it is sufficient if no untreated portions such as pinholes are generated during the process. Thus, the Cu plating layer may be thinner than the outermost aluminum plating layer, as long as the adhesion between the Cu plating layer and the aluminum plating layer is ensured.

[0043] Furthermore, the hardness of an aluminum plating layer is generally lower than that of copper or nickel. Furthermore, copper is generally lower than that of nickel. Therefore, by forming a Ni plating layer, a Cu plating layer, and an aluminum plating layer in that order on the substrate 1, the hardness of adjacent materials in each layer becomes similar. By approximating the hardness of adjacent layers in this manner, peeling between layers is less likely to occur even when the layers deform in accordance with deformation of the substrate 1, resulting in a plated product with good flexibility. The preferred method for measuring hardness is Vickers hardness (measurement conditions: test force 25 g). According to this measurement method, the hardness of high-purity aluminum ranges from 35 Hv to 170 Hv, the hardness of copper ranges from 100 Hv to 200 Hv, and the hardness of nickel ranges from 400 Hv to 700 Hv. Although there is some overlap in the hardness ranges of the two, the hardness can be adjusted by controlling the film formation conditions during film formation, so the hardness of the aluminum plating layer actually formed on a non-conductive substrate is preferably harder than the copper plating layer and softer than the electroless Ni plating layer.Furthermore, it is preferable that the Ni plating layer, which is the hardest layer, has the thinnest layer thickness.

[0044] As described above, according to this embodiment, the surface of the non-conductive member can be given an appearance with excellent design. Furthermore, by forming an anodized coating, the surface can be colored or colored in any color, such as white, black, red, or blue, and the color can also be changed depending on the part.

[0045] Furthermore, by using an electrolyte containing (1) dialkyl sulfone, (2) aluminum halide, and (3) a desired nitrogen-containing compound to form the aluminum plating layer 5, it is possible to perform aluminum plating at a relatively low temperature of 80°C to 110°C, thereby suppressing deformation of the substrate 1. The disclosure of the present specification also includes disclosure of the following aspects of the invention, which are intended to enable the production of plated products and the like that can achieve high designability on non-conductive substrates.

[0046] In order to achieve the above-mentioned object, one aspect of the present invention is a plated product comprising a non-conductive substrate, an electroless plating layer formed on the surface of the substrate, and an aluminum plating layer laminated on the electroless plating layer.

[0047] According to the first aspect of the present invention, by forming an electroless plating layer on the surface of a non-conductive base material, it is possible to form an aluminum plating layer by electrolytic plating, thereby improving design properties.

[0048] Furthermore, by forming a Cu plating layer between the Ni plating layer and the aluminum plating layer as the electroless plating layer, peeling between the aluminum plating layer and the electroless plating layer can be suppressed. To reliably achieve this effect, it is desirable that the Ni plating layer be 0.1 μm to 5 μm thick and the Cu plating layer be 1 to 30 μm thick. Furthermore, it is more desirable that the Ni plating layer be 0.1 μm to 1 μm thick and the Cu plating layer be 1 μm to 30 μm thick, with the Ni plating layer being thinner than the Cu plating layer.

[0049] In this case, by setting the thickness of the aluminum plating layer within an appropriate range, it is possible to achieve both high designability and manufacturability.

[0050] Furthermore, if the base material is a fiber-reinforced plastic, high strength can be ensured.

[0051] Another aspect of the present invention is a method for manufacturing a plated product, comprising the steps of: forming an electroless Ni plating layer on a non-conductive base material; forming a Cu plating layer on a surface of the Ni plating layer; and laminating an aluminum plating layer on the surface of the Cu plating layer by electrolytic plating.

[0052] According to another aspect of the present invention, peeling of the aluminum plating layer and the electroless plating layer can be suppressed by forming a Cu plating layer between the electroless Ni plating layer and the aluminum plating layer. Furthermore, high designability can be obtained by further forming an anodized coating on the surface of the aluminum plating layer.

[0053] Furthermore, by using an electrolyte solution comprising a dialkyl sulfone, an aluminum halide, and a nitrogen-containing compound, it is possible to carry out the operation at a lower temperature than when a molten salt is used, and the operation is safe and easy to handle.

[0054] Furthermore, by providing an oxide film removal process for removing the oxide film from the Ni plating layer between the process of forming the Ni plating layer and the process of forming the Cu plating layer, peeling of the Ni plating layer and the Cu plating layer can be more reliably suppressed.

[0055] Furthermore, in the step of forming an aluminum plating layer, the member on which the Cu plating layer has been formed is immersed in a non-aqueous electrolytic solution, and then electrolysis is performed after a holding time of 3 seconds or more. This makes it possible to remove the oxide film on the surface of the Cu plating layer using the electrolytic solution before plating.

[0056] Example 1 The design properties of this embodiment were confirmed. A 10 cm x 10 cm x 0.3 cm CFRP substrate was used. The plating area was 10 cm x 8 cm x 2 surfaces. Ni electroless plating and aluminum electrolytic plating were performed on this substrate. Alternatively, a Ni electroless plating layer, a Cu electrolytic plating layer, and aluminum electrolytic plating were performed. The electrolyte for aluminum electrolytic plating was a 2 L solution containing 10 mol of dimethyl sulfone, 3.8 mol of aluminum chloride, 0.2 mol of ammonium chloride, and 1 mol of tetramethylammonium chloride, and the current density was 40 to 50 mA / cm. ２The solution temperature was 95°C to 100°C. The anodizing treatment consisted of a primary electrolytic treatment using an electrolyte to form an anodized film, followed by a secondary electrolytic treatment to color the film. Visual evaluation revealed no surface defects, such as pinholes, and confirmed that an aluminum plating layer with a metallic texture had been formed on the CFRP substrate. Visual evaluation was conducted both before and after the anodizing treatment. The aluminum plating layer was directly touched to check for peeling, but no surface defects, such as pinholes, or peeling were observed. Furthermore, it was confirmed that anodizing the aluminum plating layer could produce a plated product with a four-color (white, black, red, and blue) design on a CFRP substrate. To evaluate adhesion under severe conditions, a "cross-cut test" was conducted as Example 2, described below.

[0057] Example 2: Plated products manufactured using the same substrate and manufacturing method as in Example 1 were evaluated for adhesion between the substrate and the aluminum plating layer under conditions more severe than those in Example 1. The results are shown in Table 1. Table 1 also shows the results of visual observations and the results of surface contact peeling tests conducted in Example 1. In Table 1, sample numbers with a "-" in the "Cu plating layer thickness" category indicate that no Cu plating layer was formed, and that the aluminum plating layer was formed on the Ni plating layer. Additionally, samples with a "good" rating in the "condition of aluminum plating layer and anodized coating" category indicate that no pinholes were found in the visual inspection results after the formation of the aluminum plating layer and the anodized coating, and that no peeling was found when the surface was rubbed with a hand.

[0058]

[0059] In Nos. 1 to 8, an aluminum plating layer was formed directly on the surface of the electroless plating layer, and in Nos. 9 and 10, a Cu electroplating layer was formed between the electroless plating layer and the aluminum plating layer as an adhesion improving layer.

[0060] The obtained samples were subjected to a "cross-cut test." A 5 x 5 grid was created using a cutter, and cellophane tape was applied and peeled off. 25 squares in which no film peeled off were recorded as "no peeling." As a result, for Nos. 9 and 10, which had an adhesion-improving layer, there was no peeling between the substrate and the aluminum plating layer, ensuring high adhesion.

[0061] Next, to evaluate the relationship between the plating conditions and the structure of the plated film (layer), electrolysis was performed using an aluminum electrolytic bath, and the electrodeposited film on the surface of the cathode electrode, which corresponds to the plated layer in electrolytic plating, was observed. An AC2A alloy was used as the anode electrode, and the anode current density and cathode current density were 10 mA / cm. ２ ~80mA / cm ２ (median value was

[45] mA / cm ２ Figure 3A is an SEM photograph of the surface of the electrodeposited film, and Figure 3B is an SEM photograph of the cross section of the electrodeposited film. AC2A alloy was used as the anode electrode, and the current density (median value) was 40 mA / cm. ２ As a result, particles that appear to be Cu (whitish particulate parts in the photograph) were confirmed in some parts of the cross section, which indicates that Cu ions were reduced on the surface of the cathode electrode.

[0062] On the other hand, AC2A alloy was used as the anode electrode, and the anode current density and cathode current density were set to 10 mA / cm ２ Electrolysis was carried out at a constant current density of 20 mA / cm. Figure 4A is an SEM photograph of the surface of the electrodeposited film, and Figure 4B is an SEM photograph of the cross section of the electrodeposited film. AC2A alloy was used as the anode electrode, and the current density was 20 mA / cm. ２ In the following example, no Cu was observed in the cross section, and a highly pure electrodeposited film was obtained. Thus, even when a low-purity alloy (e.g., a cast alloy with a high content of Cu, Si, Fe, etc.) is used as the anode, a highly pure aluminum plating layer can be obtained by suppressing the anode current density.

[0063] The inventors have found that during electroplating, when metal ions are eluted from an anode electrode, the type of eluted metal ions varies depending on the current density at the anode electrode. For example, because Cu has a higher standard electrode potential than aluminum, aluminum is preferentially ionized at the anode electrode in an equilibrium state, but under certain conditions, Cu also ionizes.

[0064] For example, in the material constituting the anode electrode, segregated portions of Cu, Si, etc. (crystallized portions of Cu and Si) appear on the surface due to the ionization of aluminum. When these segregated portions fall off, high-purity aluminum can be deposited (plated). However, as the current density of the anode electrode increases, for example, the ionization of Cu, which is more noble than aluminum, progresses, resulting in the inclusion of Cu in the plating. Comparing Figures 3A and 4A, it can be seen that Figure 3A, in which the high current density of the anode electrode results in finer crystal grains containing Cu and other elements, is smaller. Preferably, the aluminum alloy used for the anode electrode contains 0.07 wt% or more of Cu. Using an aluminum alloy containing a predetermined amount of Cu for the anode electrode improves the metallic luster of the surface of the aluminum plating layer formed on the cathode electrode. However, it is preferable that the Cu content does not exceed 2.00 wt%.

[0065] Thus, the inventors discovered that increasing the amount of impurities in the plating can refine the crystal grains. Furthermore, visual inspection of the surface condition of the aluminum plating layer confirmed that a glossy surface was formed. Therefore, in order to reduce the surface roughness of the plating, a material containing a large amount of impurities, such as an aluminum alloy containing Cu, Si, Fe, etc., was selected as the anode electrode material, and the anode current density was set to 40 mA / cm. ２ ~200mA / cm ２ It is desirable to do so.

[0066] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not limited to the above-described embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas described in the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention.

[0067] DESCRIPTION OF SYMBOLS 1....Substrate 3....Electroless plating layer 5....Aluminum plating layer 7....Anodic oxide coating 9....Adhesion improving layer 10...Plated product

Claims

1. A method for manufacturing a plated product, comprising: forming an electroless Ni plating layer on a non-conductive base material; forming a Cu plating layer on the surface of the Ni plating layer; laminating an aluminum plating layer on the surface of the Cu plating layer by electrolytic plating; Equipped with The electrolyte used when laminating the aluminum plating layer is dialkyl sulfones, aluminum halide, and the composition contains at least one nitrogen-containing compound selected from the group consisting of ammonium halides, hydrogen halide salts of primary amines, hydrogen halide salts of secondary amines, hydrogen halide salts of tertiary amines, and quaternary ammonium salts represented by the general formula: R 1 R 2 R 3 R 4 N.X (R 1 to R 4 are the same or different alkyl groups, and X is a counter anion for the quaternary ammonium cation); a step of forming a Cu plating layer on the surface of the Ni plating layer and a step of forming the aluminum plating layer, the step of immersing the base material on which the Cu plating layer has been formed in the electrolytic solution, and then vibrating the base material on which the Cu plating layer has been formed for 3 seconds or more, or stirring the electrolytic solution for 3 seconds or more.

2. 2. The method for producing a plated product according to claim 1, further comprising the step of anodizing the surface of the aluminum plating layer.

3. A method for manufacturing a plated product as described in claim 1, characterized in that the substrate is fiber-reinforced plastic.

4. A method for manufacturing a plated product as described in claim 1, characterized in that in the process of forming the aluminum plating layer, the member on which the Cu plating layer is formed is used as the cathode, and the material of the anode is aluminum.