Composite parts and heat dissipation parts

Abstract

Provided is a composite member in which a substrate has excellent corrosion resistance and excellent heat dissipation. The composite member is provided with: a substrate composed of a composite material containing magnesium or a magnesium alloy and SiC; and a coating layer provided on a surface of the substrate, the coating layer having: a topmost surface layer provided on a topmost surface, the topmost surface layer containing nickel and phosphorus; and an intermediate layer provided immediately below the topmost surface layer, the intermediate layer containing copper as a main component, the thickness of the intermediate layer being 30 μm or more.

Description

[0001] This application is a divisional application of application number 202080023413.5, filed on March 5, 2020, entitled "Composite Components and Heat Dissipation Components". Technical Field

[0002] This disclosure relates to composite components and heat dissipation components. This application claims priority based on Japanese Patent Application No. 2019-070853, filed on April 2, 2019. The entire contents of that Japanese patent application are incorporated herein by reference. Background Technology

[0003] The composite component in Japanese Patent Application Publication No. 2012-144767 (Patent Document 1) comprises:

[0004] A substrate made of a composite material; and a metal coating covering the surface of the substrate. The composite material is made of magnesium or a magnesium alloy combined with SiC. The metal coating, starting from the substrate side, consists of a base layer, a zinc layer, a copper plating layer, and a nickel plating layer in sequence.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-144767 Summary of the Invention

[0008] The composite component disclosed herein includes:

[0009] A substrate made of a composite material containing pure magnesium or magnesium alloy and SiC; and

[0010] A coating layer disposed on the surface of the substrate.

[0011] The coating layer has:

[0012] The outermost layer set on the outermost surface; and

[0013] The middle layer is located directly below the outermost layer.

[0014] The outermost layer contains nickel and phosphorus.

[0015] The intermediate layer is mainly composed of copper.

[0016] The thickness of the intermediate layer is 30 μm or more.

[0017] The heat dissipation component disclosed herein is composed of the composite component disclosed herein. Attached Figure Description

[0018] [ Figure 1 ] Figure 1 A cross-sectional view showing the outline of the composite component according to Embodiment 1.

[0019] [ Figure 2 ] Figure 2 An explanatory diagram showing the outline of the texture of the substrate of the composite component according to Embodiment 1.

[0020] [ Figure 3 ] Figure 3 A cross-sectional view showing the outline of the coating layer of the composite component according to Embodiment 1.

[0021] [ Figure 4 ] Figure 4 A cross-sectional view showing the outline of the coating layer of the composite component according to Embodiment 2. Detailed Implementation

[0022] [The problem this disclosure aims to solve]

[0023] The goal is to develop a composite component with excellent corrosion resistance and heat dissipation on a substrate.

[0024] Therefore, one objective of this disclosure is to provide a composite component with excellent corrosion resistance and heat dissipation of the substrate. Furthermore, another objective of this disclosure is to provide a heat dissipation component with excellent corrosion resistance and heat dissipation of the substrate.

[0025] [The Effects of This Disclosure]

[0026] The composite components and heat dissipation components disclosed herein exhibit excellent corrosion resistance and heat dissipation properties of the substrate.

[0027] [Description of embodiments of this disclosure]

[0028] The inventors investigated the corrosion resistance of a substrate in a composite component having an outermost layer made of nickel and an intermediate layer made of copper disposed directly below the outermost layer. Generally, nickel has a greater tendency to ionize than copper. Therefore, the inventors concluded that in corrosive environments such as salt water, the outermost layer, which is made of nickel rather than copper, becomes a sacrificial layer that preferentially corrodes. As a result, conventional composite components can suppress corrosion of the intermediate layer, thereby suppressing corrosion of the substrate.

[0029] However, the substrate corroded under corrosive conditions. The inventors conducted in-depth research into the cause and made the following findings: Under corrosive conditions, the ionization tendency of nickel and copper is reversed. That is, under corrosive conditions, the ionization tendency of copper becomes greater than that of nickel. Therefore, corrosion occurs not in the outermost layer but in the intermediate layer. When the outermost layer is composed of nickel, even with a thick intermediate layer, it is difficult to suppress substrate corrosion.

[0030] Therefore, the inventors further conducted in-depth research on the composition of the coating layer, and as a result, the following findings were obtained. By including phosphorus in addition to nickel in the outermost layer, and increasing the thickness of the intermediate layer, which is mainly composed of copper and is located directly below the outermost layer, the corrosion resistance of the substrate can be improved. The present invention is based on these findings. First, embodiments of the present disclosure are listed and described.

[0031] (1) One aspect of the composite component disclosed herein includes:

[0032] A substrate made of a composite material containing pure magnesium or magnesium alloy and SiC; and

[0033] A coating layer disposed on the surface of the substrate.

[0034] The coating layer has:

[0035] The outermost layer set on the outermost surface; and

[0036] The middle layer is located directly below the outermost layer.

[0037] The outermost layer contains nickel and phosphorus.

[0038] The intermediate layer is mainly composed of copper.

[0039] The thickness of the intermediate layer is 30 μm or more.

[0040] In the above configuration, the substrate exhibits excellent corrosion resistance. This is because the outermost layer, positioned directly above the copper-based intermediate layer, contains phosphorus in addition to nickel. Furthermore, the intermediate layer is sufficiently thick. Since the outermost layer contains phosphorus in addition to nickel, even with the copper-based intermediate layer positioned directly below it, the ionization tendency of the constituent materials of the outermost and intermediate layers remains unchanged under corrosive conditions. That is, the ionization tendency of the constituent materials of the outermost layer is greater than that of the intermediate layer. Therefore, even under corrosive conditions, it is not the intermediate layer but the outermost layer that becomes the sacrificial layer preferentially corroded. This suppresses corrosion of the intermediate layer. Furthermore, because the intermediate layer is sufficiently thick, corrosion of the substrate is also suppressed.

[0041] Furthermore, the above-described structure exhibits excellent heat dissipation. This is because the thickness of the intermediate layer, primarily composed of copper with high thermal conductivity, is sufficiently thick. Therefore, this structure is suitable for use in heat dissipation components.

[0042] Furthermore, the above-described structure exhibits excellent adhesion to solder. This is because the outermost layer contains nickel, which provides excellent compatibility with solder. Consequently, the above-described structure provides excellent adhesion to components that are joined by solder, such as semiconductor elements of a semiconductor device or insulating substrates on which semiconductor elements are mounted.

[0043] (2) As one method of the above-mentioned composite component, the following methods can be listed:

[0044] The coating layer has an inner layer disposed directly below the intermediate layer.

[0045] The inner layer contains nickel and phosphorus.

[0046] The above configuration improves the adhesion between the substrate and the coating layer. This is because the inner layer contains nickel and phosphorus, thus exhibiting good compatibility with both the substrate and the intermediate layer.

[0047] (3) As one method of the above-mentioned composite component, the following methods can be listed:

[0048] The thickness of the intermediate layer is less than 200 μm.

[0049] The above-described configuration effectively suppresses increases in the coefficient of thermal expansion, weight, and yield. This is because the thickness of the intermediate layer is not excessive. Thus, the configuration exhibits excellent heat dissipation as described above, and by suppressing the increase in the coefficient of thermal expansion, it is more suitable for use as a heat dissipation component. In particular, the configuration also exhibits excellent adhesion to solder as described above, making it suitable for heat dissipation components of parts joined by solder. This is because the increase in the coefficient of thermal expansion is suppressed, and even under thermal cycling, the part is less likely to peel off from the composite component due to thermal expansion and contraction.

[0050] (4) The heat dissipation component in one aspect of this disclosure is composed of the composite component described in any one of (1) to (3) above.

[0051] The above-described configuration exhibits excellent heat dissipation. This is because the heat dissipation component is constructed from a composite component with excellent heat dissipation properties. In particular, the above-described configuration readily and effectively dissipates heat from components bonded by solder. This is because the heat dissipation component is constructed from a composite component with excellent adhesion to the solder. Furthermore, the above-described configuration can be appropriately used even in corrosive environments. This is because the heat dissipation component is constructed from a composite component with a substrate possessing excellent corrosion resistance.

[0052] [Details of the embodiments of this disclosure]

[0053] The following describes in detail the embodiments of this disclosure. The same symbols in the figures represent substances with the same name.

[0054] Implementation Method 1

[0055] [Composite Components]

[0056] Reference Figures 1 to 3 The composite component 1 of Embodiment 1 will be described. The composite component 1 of this embodiment includes a substrate 2 and a coating layer 3. The substrate 2 is made of a composite material containing pure magnesium (Mg) or a Mg alloy and SiC (silicon carbide). The coating layer 3 is disposed on the surface of the substrate 2. One characteristic of the composite component 1 of this embodiment is that the coating layer 3 has a specific outermost layer 32 disposed on the outermost surface and a specific intermediate layer 31 disposed directly below the outermost layer 32. Figure 3 The following is a detailed explanation of each component. Figure 2 Will Figure 1 The area enlarged by the dashed circle shown on the substrate 2 is illustrated. Figure 3 Will Figure 1 The area enlarged by the dashed ellipse near the boundary between the substrate 2 and the coating layer 3 is shown in the image.

[0057] [Substrate]

[0058] The substrate 2 is composed of a composite material containing metal 20 and non-metal 22. Figure 2 The substrate 2 can be made of known materials.

[0059] (Metal)

[0060] Metal 20 is composed of pure Mg or a Mg alloy. Pure Mg contains 99.8% by mass or more of Mg, with the balance consisting of unavoidable impurities. The Mg alloy contains additive elements, with the balance consisting of Mg and unavoidable impurities. Examples of additive elements include at least one element selected from the group consisting of Li (lithium), Ag (silver), Ni (nickel), Ca (calcium), Al (aluminum), Zn (zinc), Mn (manganese), Si (silicon), Cu (copper), Zr (zirconium), Be (beryllium), Sr (strontium), Y (yttrium), Sn (tin), Ce (cerium), and rare earth elements (excluding Y and Ce). When the Mg alloy is set to 100% by mass, the total content of these elements is preferably 20% by mass or less. For a substrate 2 with a total content of 20% by mass or less, the decrease in thermal conductivity can be suppressed because the content of additive elements is not too high. The Mg alloy can be an alloy of known specifications. Compared to a substrate 2 where the metal 20 is made of a Mg alloy, a substrate 2 where the metal 20 is made of pure Mg tends to have superior thermal conductivity. On the other hand, compared to a substrate 2 where the metal 20 is made of pure Mg, a substrate 2 where the metal 20 is made of a Mg alloy tends to have superior corrosion resistance, etc.

[0061] (Non-metallic)

[0062] Non-metallic component 22 is made of SiC. SiC has high thermal conductivity. Therefore, this substrate 2 is suitable for use as a heat dissipation component. Furthermore, SiC has a smaller coefficient of thermal expansion compared to Mg. Therefore, this substrate 2 exhibits excellent matching of the coefficient of thermal expansion with components such as semiconductor elements of semiconductor devices (not shown) and insulating substrates on which semiconductor elements are mounted. Thus, this substrate 2 is suitable for heat dissipation components such as semiconductor elements.

[0063] <Form of Existence>

[0064] Representative states of the non-metallic material 22 include: powder form and mesh form. In powder form, the non-metallic material 22 exists as powder particles within the matrix of the metal 20. Mesh form refers to a state where the non-metallic material 22 is connected by a mesh-like structure, and the spaces between the non-metallic materials 22 are filled with the metal 20. The non-metallic material 22 in the substrate 2 essentially maintains the composition, shape, and size of the raw material used. If SiC powder is used in the raw material, the non-metallic material 22 exists in the aforementioned powder form. Furthermore, if a shaped body such as a mesh-like SiC porous body is used in the raw material, the non-metallic material 22 exists in the aforementioned mesh form.

[0065] <content>

[0066] When substrate 2 is set to 100% by volume, the SiC content in substrate 2 is preferably 50% by volume or more. Since the SiC content is 50% by volume or more, the thermal conductivity is easily increased, and the coefficient of thermal expansion is easily decreased. The higher the SiC content in substrate 2, the easier it is to increase the thermal conductivity of substrate 2, and the easier it is to decrease the coefficient of thermal expansion of substrate 2. The SiC content in substrate 2 is further preferably 60% by volume or more, particularly preferably 65% ​​by volume or more. The SiC content in substrate 2 is preferably (for example) 90% by volume or less. The reason for this is that with a SiC content of 90% by volume or less, the manufacturability of substrate 2 is excellent. The SiC content in substrate 2 is further preferably 85% by volume or less.

[0067] (other)

[0068] In addition to SiC, substrate 2 may also contain the following nonmetals. Examples of nonmetals include at least one selected from Si3N4, Si, MgO, Mg2Si, MgB2, Al2O3, AlN, SiO2, diamond, and graphite. These nonmetals have a lower coefficient of thermal expansion than Mg, excellent thermal conductivity, and are less likely to react with Mg.

[0069] (Plane shape)

[0070] There is no particular limitation on the planar shape of the substrate 2, and it can be appropriately selected according to the application of the composite component 1. A typical example of the planar shape of the substrate 2 is a rectangle. In addition, the planar shape of the substrate 2 can also include: circles, ellipses, and various polygons other than rectangles.

[0071] (thickness)

[0072] There is no particular limitation on the thickness of the substrate 2, and it can be appropriately selected according to the application of the composite component 1. When the composite component 1 is used as a heat dissipation component for, for example, semiconductor elements, the thickness of the substrate 2 may be 10 mm or less, and more specifically 6 mm or less.

[0073] [Covering layer]

[0074] The coating layer 3 is disposed on the surface of the substrate 2. Figure 1The coverage area of ​​the coating layer 3 can be appropriately selected according to the application of the composite component 1. When the composite component 1 is used as a heat dissipation component for semiconductor elements, etc., one side of the substrate 2 on opposite sides serves as a mounting surface for mounting the semiconductor element. The other side serves as a cooling surface in contact with a cooling device. Typically, solder is applied to the mounting surface. Therefore, the coverage area of ​​the coating layer 3 can be listed as the area on the mounting surface where at least solder is applied. The coverage area of ​​the coating layer 3 can be the entire area covering the mounting surface of the substrate 2, the entire area covering both the mounting surface and the cooling surface of the substrate 2, or the entire surface area of ​​the substrate 2. In this embodiment, the coating layer 3 is a two-layer structure having an intermediate layer 31 and an outermost layer 32 sequentially from the substrate 2 side. Figure 3 ). Figure 3 The thicknesses of the intermediate layer 31 and the outermost layer 32 are shown schematically and do not necessarily correspond to the actual thicknesses.

[0075] (Middle layer)

[0076] The intermediate layer 31 is disposed directly below the outermost layer 32. In this embodiment, the intermediate layer 31 is disposed directly above the substrate 2.

[0077] The intermediate layer 31 is primarily composed of Cu. "Primarily composed of Cu" means that when all constituent elements of the intermediate layer 31 are set to 100% by mass, the Cu content is 98.0% by mass or more. The Cu content in the intermediate layer 31 is further preferably 99.0% by mass or more, and particularly preferably 99.5% by mass or more. The intermediate layer 31 may also be composed essentially only of Cu. "Essentially only of Cu" means that unavoidable impurities other than Cu are permissible. Here, the composition and content of the intermediate layer 31 are determined by energy-dispersive X-ray diffraction (EDX).

[0078] The thickness of the intermediate layer 31 can be 30 μm or more. For composite components 1 with an intermediate layer 31 thickness of 30 μm or more, the substrate 2 exhibits excellent corrosion resistance and heat dissipation. This is because the thickness of the intermediate layer 31 is sufficiently thick. The thickness of the intermediate layer 31 is preferably 200 μm or less. Composite components 1 with an intermediate layer 31 thickness of 200 μm or less easily suppress the increase in the coefficient of thermal expansion, the increase in weight, and the decrease in yield. This is because the thickness of the intermediate layer 31 is not excessive. This composite component 1 exhibits excellent heat dissipation and can suppress the increase in the coefficient of thermal expansion, thus making it suitable as a heat dissipation component. The thickness of the intermediate layer 31 is further preferably 50 μm or more and 150 μm or less, and particularly preferably 80 μm or more and 100 μm or less. The method for determining the thickness of the intermediate layer 31 will be described later.

[0079] (outermost layer)

[0080] The outermost layer 32 is disposed on the outermost surface of the coating layer 3. This outermost layer 32 is positioned directly above the intermediate layer 31. The outermost layer 32 is composed of Ni and P (phosphorus). Since the Ni-containing outermost layer 32 has excellent compatibility with solder, it exhibits excellent adhesion to the solder. Therefore, the outermost layer 32 exhibits excellent adhesion to components such as semiconductor devices bonded by solder. Furthermore, because the outermost layer 32 contains P in addition to Ni, even with the intermediate layer 31 positioned directly below it, it functions as a sacrificial layer for preferential corrosion in corrosive environments. Therefore, the outermost layer 32 can suppress the corrosion of the intermediate layer 31. Thus, the outermost layer 32 can suppress the corrosion of the substrate 2.

[0081] When all constituent elements of the outermost layer 32 are set to 100% by mass, the Ni content in the outermost layer 32 can be listed as 87% by mass or more and 99% by mass or less. When all constituent elements of the outermost layer 32 are set to 100% by mass, the P content in the outermost layer 32 can be listed as 1% by mass or more and 13% by mass or less. The lower the P content, the better the adhesion between the outermost layer 32 and the solder. The higher the P content, the better the corrosion resistance of the outermost layer 32. The P content in the outermost layer 32 can be appropriately selected within the above range according to the desired characteristics. The outermost layer 32 can also be composed of essentially only Ni and P. Composed of essentially only Ni and P means that unavoidable impurities are allowed in addition to Ni and P. Similar to the intermediate layer 31 described above, the composition and content of the outermost layer 32 are obtained by EDX.

[0082] The thickness of the outermost layer 32 is preferably, for example, 0.1 μm or more and 6.0 μm or less. In composite components 1 with an outermost layer 32 thickness of 0.1 μm or more, the substrate 2 exhibits excellent corrosion resistance and excellent adhesion to the solder. This is because the outermost layer 32 is sufficiently thick. Composite components 1 with an outermost layer 32 thickness of 6.0 μm or less easily suppress the increase in the coefficient of thermal expansion, the decrease in thermal conductivity, and the decrease in yield. The thickness of the outermost layer 32 is further preferably 1.5 μm or more and 5.0 μm or less, and particularly preferably 2.0 μm or more and 4.0 μm or less. The method for determining the thickness of the outermost layer 32 will be described later.

[0083] [Manufacturing Method]

[0084] The composite component 1 of this method can be manufactured by sequentially forming an intermediate layer 31 and an outermost layer 32 on the surface of a substrate 2, starting from the substrate 2 side. The substrate 2 can be prepared by known methods such as melt infiltration, pressure melt infiltration, powder metallurgy, and melting, or by purchasing commercially available products. The intermediate layer 31 is formed by direct electroplating. Direct electroplating is performed by attaching a catalyst to the substrate 2. Examples of catalysts include palladium and carbon. Alternatively, the intermediate layer 31 can be formed by electroplating Cu after electroless Cu plating. Furthermore, the intermediate layer 31 can be formed by electroplating Cu after sputtering Cu. The outermost layer 32 is formed by a plating method, such as electroplating or electroless plating.

[0085] [Effects]

[0086] For the composite component 1 of this embodiment, the substrate 2 exhibits excellent corrosion resistance and heat dissipation. Therefore, the composite component 1 of this embodiment can be used as a heat dissipation component in corrosive environments. Furthermore, the composite component 1 of this embodiment exhibits excellent adhesion to solder and excellent matching with the coefficient of thermal expansion of semiconductors, etc. Therefore, the composite component 1 of this embodiment is suitable for heat dissipation components of semiconductor elements, etc., bonded by solder.

[0087] Implementation Method 2

[0088] [Composite Components]

[0089] Reference Figure 4 The composite component 1 of Embodiment 2 will be described. The composite component 1 of this embodiment differs from the composite component 1 of Embodiment 1 in the following aspects: the coating layer 3 has a specific inner layer 30 directly below the intermediate layer 31. That is, the coating layer 3 has a three-layer structure consisting of an inner layer 30, an intermediate layer 31, and an outermost layer 32, starting from the substrate 2 side. Figure 4 It will be with Figure 3 The cross-sectional view shown is an enlarged view from the same location as the cross-sectional view shown. The following description will focus on aspects that differ from Embodiment 1. Descriptions of configurations identical to those in Embodiment 1 are omitted.

[0090] [Covering layer]

[0091] (Inner layer)

[0092] The inner layer 30 is disposed directly below the intermediate layer 31. In this embodiment, the inner layer 30 is disposed directly above the substrate 2.

[0093] The inner layer 30 contains Ni and P. The inner layer 30, containing Ni and P, exhibits excellent adhesion to the substrate 2 and the intermediate layer 31. The Ni content in the inner layer 30 can be listed within the same range as that of the outermost layer 32 described above. Similarly, the P content in the inner layer 30 can be listed within the same range as that of the outermost layer 32 described above. The inner layer 30 can be composed essentially only of Ni and P. "Essentially composed only of Ni and P" means that unavoidable impurities are permitted besides Ni and P. The Ni and P content in the inner layer 30 can be the same as or different from that of the outermost layer 32. Similar to the intermediate layer 31 described above, the material of the inner layer 30 can be obtained using EDX.

[0094] The thickness of the inner layer 30 is preferably 3.0 μm or more and 20.0 μm or less. For composite components 1 with an inner layer 30 thickness of 3.0 μm or more, the substrate 2 exhibits excellent corrosion resistance. This is because the thickness of the inner layer 30 is sufficiently thick. Composite components 1 with an inner layer 30 thickness of 20.0 μm or less easily suppress the increase in the coefficient of thermal expansion and the decrease in thermal conductivity of the composite component 1. The thickness of the inner layer 30 is further preferably 4.0 μm or more and 15.0 μm or less, and particularly preferably 6.0 μm or more and 12.0 μm or less. The thickness of the inner layer 30 may be the same as or different from the thickness of the outermost layer 32. The method for determining the thickness of the inner layer 30 will be described later.

[0095] [Manufacturing Method]

[0096] The composite component 1 of this method can be manufactured by sequentially forming an inner layer 30, an intermediate layer 31, and an outermost layer 32 on the surface of a substrate 2, starting from the substrate 2 side. The preparation of the substrate 2 is as described above. Similar to the formation of the outermost layer 32, the inner layer 30 is formed by a plating method or the like. The formation of the intermediate layer 31 and the outermost layer 32 is as described above.

[0097] [Effects]

[0098] The composite component 1 of this embodiment can achieve the same effect as the composite component 1 of Embodiment 1. Furthermore, compared with the composite component 1 of Embodiment 1, the coating layer 3 of the composite component 1 of this embodiment has an inner layer 30, thus the adhesion between the substrate 2 and the coating layer 3 is excellent.

[0099] Example

[0100] This embodiment will be described in more detail through examples. However, this embodiment is not limited to these examples.

[0101] Experimental Example 1

[0102] Composite components with various coatings formed on the surface of a substrate were fabricated, and the corrosion resistance of the substrate, the coefficient of thermal expansion (ppm / K), and the thermal conductivity (W / m·K) of the composite components were investigated. The substrate used was a composite material containing pure Mg and SiC. The SiC content in the substrate was set to 70% by volume. The substrate thickness was 5 mm.

[0103] [Samples No. 1 to No. 4]

[0104] The composite components of samples No. 1 to No. 4 were fabricated as follows: A two-layer structure, consisting of a first layer and a second layer, was formed, starting from the substrate side directly above the substrate. That is, the second layer was the outermost layer. Furthermore, the first layer was located directly below the outermost layer. The first layer was a Cu plating layer consisting essentially only of Cu. The formation of the first layer was performed by direct electroplating. Direct electroplating was performed using palladium as a catalyst powder attached to the substrate. The thickness of the first layer varied by different processing times. The second layer was a Ni-P plating layer consisting essentially only of Ni and P. The formation of the second layer was performed by electroless plating. The electroless plating solution used was Topnicoron LPH-LF manufactured by Okuno Pharmaceutical Co., Ltd. The temperature of the plating solution was set to 85°C. The processing time was set to 15 minutes. The concentration of P in the second layer was 2% by mass. The concentration of P was determined using EDX as described above.

[0105] [Samples No. 5, No. 6]

[0106] Except for the difference in the phosphorus content of the second layer, composite components No. 5 and No. 6 were fabricated in the same manner as sample No. 2. That is, in the composite components of samples No. 5 and No. 6, the second layer is the outermost layer. Furthermore, in the composite components of samples No. 5 and No. 6, the first layer is located directly below the outermost layer. In samples No. 5 and No. 6, the type of electroless plating solution, the temperature of the plating solution, and the processing time used in the formation of the second layer differ from those of sample No. 2. Specifically, in sample No. 5, the plating solution used was ICP Nicolon GM (NP) manufactured by Okuno Pharmaceutical Co., Ltd. The temperature of the plating solution was set to 80°C. The processing time was set to 13 minutes. In sample No. 6, the plating solution used was Top Nicolon SA-98-LF manufactured by Okuno Pharmaceutical Co., Ltd. The temperature of the plating solution was set to 90°C. The processing time was set to 13 minutes. The concentration of P in the second layer of the composite component of sample No. 5 is 6% by mass. The concentration of P in the second layer of the composite component of sample No. 6 is 11% by mass. Similarly, the concentration of P in each second layer is obtained by EDX.

[0107] [Samples No. 7 to No. 10]

[0108] The composite components of samples No. 7 to No. 10 were fabricated as follows: a three-layer coating structure, consisting of a first layer, a second layer, and a third layer, was formed sequentially above the substrate, starting from the substrate side. That is, the third layer was the outermost layer. Furthermore, the second layer was disposed directly below the outermost layer. Similarly, the first layer was disposed directly below the second layer. Like the second layer of sample No. 1, both the first and third layers were formed as Ni-P coatings (P content was 2% by mass), consisting essentially only of Ni and P. The thicknesses of the first and third layers were varied by changing the processing time. Like the first layer of samples No. 1, the second layer was formed as a Cu coating, consisting essentially only of Cu.

[0109] [Sample No. 101, No. 102]

[0110] Except for the difference in the thickness of the first layer, the composite component of Specimen No. 101 was manufactured in the same manner as Specimen No. 1. In the composite component of Specimen No. 101, the second layer is the outermost layer. Furthermore, in the composite component of Specimen No. 101, the first layer is the layer located directly below the outermost layer. Except for the difference in the thickness of the second layer, the composite component of Specimen No. 102 was manufactured in the same manner as Specimen No. 7. In the composite component of Specimen No. 102, the third layer is the outermost layer. Furthermore, in the composite component of Specimen No. 102, the second layer is the layer located directly below the outermost layer. Furthermore, in the composite component of Specimen No. 102, the first layer is the layer located directly below the second layer.

[0111] [Sample No. 103]

[0112] The composite component of Specimen No. 103 was fabricated as follows: a two-layer structure, consisting of a first layer and a second layer, was formed, starting from the substrate side directly above the substrate. That is, the second layer is the outermost layer. Furthermore, the first layer is disposed directly below the outermost layer. The first layer is formed to be essentially composed of Zr. The formation of the first layer was performed through a chemical formation process. Similar to the second layer of Specimen No. 1, the second layer was formed to be a Ni-P plating, essentially composed only of Ni and P.

[0113] [Sample No. 104]

[0114] The composite component of Specimen No. 104 was fabricated by forming a coating layer consisting only of the first layer directly above the substrate. Similar to the second layer of Specimen No. 1, the first layer was formed as a Ni-P plating consisting essentially only of Ni and P.

[0115] [Sample No. 105]

[0116] The composite component of Specimen No. 105 was fabricated as follows: a two-layer structure, consisting of a first layer and a second layer, was formed, starting from the substrate side directly above the substrate. That is, the second layer is the outermost layer. Furthermore, the first layer is disposed directly below the outermost layer. Similar to the second layer of Specimen No. 1, the first layer was formed as a Ni-P plating, consisting essentially only of Ni and P. The second layer was formed as a Ni plating. The formation of the second layer was performed by electroplating.

[0117] [Samples No. 106 to No. 110]

[0118] The composite components of samples No. 106 to No. 110 were fabricated as follows: a three-layer coating structure, consisting of a first layer, a second layer, and a third layer, was formed sequentially above the substrate, starting from the substrate side. That is, the third layer was the outermost layer. Furthermore, the second layer was disposed directly below the outermost layer. Similarly, the first layer was disposed directly below the second layer. Similar to the second layer of sample No. 1, the first layer was formed as a Ni-P plating, consisting essentially only of Ni and P. Similar to the first layer of samples No. 1, the second layer was formed as a Cu plating, consisting essentially only of Cu. Similar to the second layer of sample No. 105, the third layer was formed as a Ni plating.

[0119] [Thickness Measurement]

[0120] The thickness of each layer was determined as follows: Each sample was processed using a cross-section polisher (CP), and a cross-section along the thickness direction was obtained. Within this cross-section, at least 10 fields of view were acquired using a scanning electron microscope. The magnification and size of each field of view are the dimensions of the entire region encompassing the thickness direction of each layer within the same field of view. In each field of view, the length of each layer along the thickness direction was measured at at least 10 locations. Within each layer, the average of all measured lengths was taken. Each average value was set as the thickness of that layer. The thicknesses of each layer are shown in Table 1.

[0121] [Evaluation of corrosion resistance]

[0122] Corrosion resistance was evaluated by conducting a salt spray test according to JIS Z 2371 (2015), and the time of pitting corrosion occurrence and corrosion status after 168 hours (hr) were investigated. A 5% (w / w) sodium chloride aqueous solution was used for the salt spray test. The test temperature was set at 35°C. The test duration was 168 hours.

[0123] The occurrence of pitting corrosion was confirmed visually. This confirmation was performed every 24 hours from the start of the test until the end of 168 hours. The results are shown in Table 1. A "-" in the pitting corrosion start time column of Table 1 indicates that no pitting corrosion occurred.

[0124] The corrosion state of each sample was visually assessed after 168 hours. The evaluation of the state after 168 hours was conducted in three stages: "A", "B", and "C". Samples without pitting corrosion were designated as "A", samples with pitting corrosion as "B", and samples that failed to maintain their shape as "C". Failure to maintain the sample shape refers to the disappearance of the four corners of the substrate or the complete coverage of the composite component's surface by corrosion products. In the case where the entire surface of the composite component was covered by corrosion products, the substrate itself had corroded. The results are shown in Table 1.

[0125] [Determination of coefficient of thermal expansion and thermal conductivity]

[0126] The coefficient of thermal expansion and thermal conductivity were determined by cutting test pieces from each sample and using a commercially available measuring instrument (NETZSCH JAPAN TMA4000SE). Thermal conductivity was measured at room temperature (approximately 20°C). The coefficient of thermal expansion was measured at an average value within the range of 30°C to 120°C. These results are shown in Table 1.

[0127] [Table 1]

[0128]

[0129] As shown in Table 1, no pitting corrosion occurred in the composite components of samples No. 1 to No. 10 from the start of the salt spray test to 168 hours later. The coefficients of thermal expansion of the composite components of samples No. 1 to No. 3 and No. 5 to No. 10 were 7.5 ppm / K and 7.6 ppm / K, respectively. In contrast, the coefficient of thermal expansion of the composite component of sample No. 4 was 7.8 ppm / K, which was higher than that of sample No. 1, etc. The thermal conductivity of the composite components of samples No. 1 to No. 10 was all above 220 W / m·K. In the composite components of samples No. 1 to No. 10, the thicker the Cu layer (the first layer in samples No. 1 to No. 6 and the second layer in samples No. 7 to No. 10), the higher the thermal conductivity tended to be.

[0130] In contrast, from the start of the salt spray test to 96 hours later, all composite components of samples No. 101 to No. 110 exhibited pitting corrosion. In particular, from the start of the salt spray test to 168 hours later, the composite components of samples No. 103 and No. 104 failed to maintain their shape.

[0131] As described above, embodiments and examples of this disclosure have been explained; however, it is initially intended that the above embodiments and examples be appropriately combined or modified in various ways.

[0132] The embodiments and examples disclosed herein should be considered exemplary in all respects and not limiting. The scope of the invention is defined by the claims, not by the foregoing embodiments and examples, and is intended to include all modifications with the same meaning and scope as the claims.

[0133] Explanation of symbols

[0134] 1 Composite component, 2 Substrate, 20 Metal, 22 Non-metal, 3 Coating layer, 30 Inner layer, 31 Intermediate layer, 32 Outer surface layer.

Claims

1. A composite component, comprising: A substrate made of a composite material containing pure magnesium or magnesium alloy and SiC; as well as A coating layer disposed on the surface of the substrate. The coating layer has: The outermost layer set on the outermost surface; and The middle layer is located directly below the outermost layer. The outermost layer is essentially composed of only nickel and phosphorus. "Essentially composed of only nickel and phosphorus" means that, in addition to nickel and phosphorus, unavoidable impurities are permissible. The intermediate layer is mainly composed of copper. The thickness of the intermediate layer is between 30 μm and 200 μm. When all the constituent elements of the outermost layer are set to 100% by mass, the nickel content in the outermost layer is between 98% and 99% by mass. When all the constituent elements of the outermost layer are set to 100% by mass, the phosphorus content in the outermost layer is more than 1% by mass and less than 2% by mass. The thickness of the outermost layer is between 0.1 μm and 6.0 μm. The outermost layer functions as a sacrificial layer that corrodes preferentially than the intermediate layer in a corrosive environment.

2. The composite component according to claim 1, wherein, The coating layer has an inner layer disposed directly below the intermediate layer and directly above the substrate. The inner layer contains nickel and phosphorus.

3. A heat dissipation component comprising the composite component as described in claim 1 or 2.

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