Metallic material

Abstract

To provide a metallic material used in a high-frequency component with a signal of a prescribed high frequency flowing inside, which can effectively reduce the transmission loss of the inner signal.SOLUTION: A metallic material 1 comprises a substrate 2 and a plating layer 3 formed on the substrate 2. The plating layer 3 including Ni and a W containing Ni-W layer 4 is used for a high-frequency component in which an electric current with a frequency of 0.1 GHz or more flows.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses a technology related to a metal material having a plating layer formed on a base material.

Background Art

[0002] In recent years, in in-vehicle radars, mobile phones, and various other communication devices, with the increase in communication speed, the increase in the amount of information, and the diversification of information, etc., electrical signals in high-frequency bands have been used. High-frequency components such as connectors, switches, shields, antennas, etc. mounted on such communication devices are preferably composed of a metal material suitable for flowing a high-frequency current.

[0003] On the other hand, currently, for components such as connectors, a metal material having a plating layer formed on a base material simply to suppress metal diffusion is generally used, and it is difficult to say that such a metal material can be suitably used for high-frequency components.

[0004] In Patent Document 1, it is described that "among others, a nickel-phosphorus alloy coating has characteristics such as high corrosion resistance, high lubricity, high hardness, and high resistivity, and is used as a plating coating for sliding members and piping facilities used under severe conditions. In addition, it is also applicable to thin-film resistors in the electronic industry or as a substitute for gold in connectors." Also, in Patent Document 2, it is described that "from the bath of Composition Example 1 (paragraph

[0016] ), a so-called high-phosphorus type (P concentration: 12 to 13 mass%) Ni-P alloy-CNT composite plating with a high phosphorus concentration can be obtained, and these composite plating films exhibit a low friction coefficient and high hardness. On the other hand, for electromagnetic shielding characteristics, a film obtained by compositing CNT with a low-phosphorus type (P concentration: 2 to 4 mass%) Ni-P alloy with a low phosphorus concentration is desired."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Especially in the transmission of high-frequency electrical signals, it is important to reduce transmission loss not only during spatial propagation but also inside communication devices.

[0007] For example, in the fifth-generation mobile communication system (5G) and the sixth-generation mobile communication system (6G), the internal signal is up-converted and transmitted as radio waves, and after reception, it is down-converted and transmitted as an internal signal. In this case, a frequency of about 10 GHz is used for the internal signal. Therefore, it may be required to reduce the transmission loss especially when a current of about 10 GHz flows.

[0008] In Patent Documents 1 and 2, it is not assumed that a metal material is used for high-frequency components that transmit high-frequency internal signals, and no attention is paid to reducing transmission loss.

[0009] This specification provides a metal material that is used for high-frequency components through which a predetermined high-frequency internal signal flows and can effectively reduce the transmission loss of the internal signal.

Means for Solving the Problems

[0010] The metal material disclosed in this specification has a base material and a plating layer formed on the base material, and the plating layer includes a Ni-W layer containing Ni and W, and is used for high-frequency components through which a current of 0.1 GHz or higher flows.

Effects of the Invention

[0011] According to the above metal material, when it is used for high-frequency components through which a predetermined high-frequency internal signal flows, the transmission loss of the internal signal can be effectively reduced.

Brief Description of the Drawings

[0012]

Figure 1

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Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the above-described metal material will be described. The metal material 1 illustrated in FIG. 1 has a base material 2 and a plating layer 3 formed on the base material 2. The plating layer 3 includes a Ni—W layer 4 containing Ni and W.

[0014] The Ni—W layer 4 has been newly found to have a significantly reduced transmission loss when an electrical signal at a high frequency of 0.1 GHz or higher flows, as compared with the Ni layer provided heretofore for suppressing the diffusion of metal from the base material. Therefore, when this metal material 1 is used for a high-frequency component through which a current at a frequency of 0.1 GHz or higher flows, the transmission loss of the internal signal in the high-frequency component can be suppressed to a small value.

[0015] Here, mainly, the details of the embodiment will be described using the metal material 1 in FIG. 1. As another embodiment, for example, there is the metal material 11 shown in FIG. 2. The metal material 11 in FIG. 2 will be described later. However, the metal materials 1 and 11 in FIGS. 1 and 2 are specific examples for easy understanding and are not limited to such specific examples. Also, for the metal material 11 in FIG. 2 described later, only the configuration different from that of the metal material 1 in FIG. 1 will be described, but the other configurations can be the same as those of the metal material 1 in FIG. 1.

[0016] (Base material) The material of the base material 2 is not particularly limited and can be any metal or alloy. The material of the base material 2 can be, for example, Cu (copper), Al (aluminum) or Fe (iron), or an alloy containing at least one of them. From the viewpoint of having high conductivity and strength, the material of the base material 2 is preferably Cu or a Cu alloy, more specifically, phosphor bronze, brass, Corson copper, oxygen-free copper, tough pitch copper, etc. In particular, the materials of the standards defined by the Copper Development Association (CDA) such as C11000, C10200, C19400, C70250, C26000 or C52100 may be used as the material of the base material 2. The dimensions and shape of the base material 2 can be appropriately changed according to the high-frequency component in which the metal material 1 is used.

[0017] (Ni-W layer) The Ni-W layer 4 that constitutes at least a part of the plating layer 3 formed on the base material 2 contains Ni (nickel) and W (tungsten). It is considered that the dielectric loss in the transmission loss becomes small because the Ni-W layer 4 contains W.

[0018] The W content of the Ni-W layer 4 is preferably 30% by mass or more. By having a W content of 30% by mass or more, the transmission loss of the Ni-W layer 4 can be reduced. More preferably, the W content is 38% by mass or more. By having a W content of 38% by mass or more, a fine crystal grain size can be achieved, and the transmission loss can be further reduced. Also, the W content is preferably 60% by mass or less. If the W content exceeds 60% by mass, the conductivity may decrease. More preferably, the W content is 44% by mass or less. This is because if the W content exceeds 44% by mass, the Ni-W layer 4 becomes amorphous and brittle. The preferred range of the W content is 30% by mass to 60% by mass. The remainder other than W mostly consists of Ni substantially, but as impurities, at least one selected from the group consisting of Cu, Pb, and Zn may be contained in a total of 15 mass ppm or less.

[0019] The above W content can be measured by TEM-EDX (energy dispersive X-ray spectroscopy) using JEM-2100F manufactured by JEOL Ltd. More specifically, the W content at the central portion in the thickness direction of the Ni-W layer 4 is measured. The measurement of the W content by TEM-EDX (energy dispersive X-ray spectroscopy) can be performed as follows. Apparatus (TEM): Field emission transmission electron microscope (JEM-2100F) manufactured by JEOL Ltd. Apparatus (EDX): Energy dispersive X-ray analyzer (JED-2300T) manufactured by JEOL Ltd. ·STEM image observation + EDX analysis Mode: STEM mode Acceleration voltage: 200 kV Spot size: 0.15 nm Magnification: 80,000 times

[0020] When the cross-section of the metal material 1 is processed by FIB-SIM (SMI3050SE manufactured by Hitachi High-Tech Corporation) and the cross-section is observed by TEM (JEM-2100F manufactured by JEOL Ltd.), the crystal lattice of the Ni-W layer 4 may be confirmed. Typically, the Ni-W layer 4 is presumed to be in a fine crystalline state, but it is not limited to this.

[0021] The thickness of the Ni-W layer 4 is preferably 1 μm to 6 μm. When the thickness of the Ni-W layer 4 is less than 1 μm, pits and pinholes are likely to occur and the corrosion resistance may decrease. On the other hand, when the thickness of the Ni-W layer 4 exceeds 6 μm, cracking may occur when the metal material 1 is bent due to the hardness of Ni-W. The thickness of the Ni-W layer 4 can be measured by a fluorescence X-ray film thickness meter. The thickness of the layers other than the Ni-W layer 4 of the plating layer 3 can also be measured in the same manner. The measurement of the plating thickness by a fluorescence X-ray film thickness meter can be performed as follows. Device: Fluorescence X-ray film thickness meter FT9500X manufactured by Hitachi High-Tech Corporation X-ray tube: Mo Detector: Drift type semiconductor detector X-ray optical system: Polycapillary method Beam diameter (diameter): 30 μm Measurement method: Thin film FP (Fundamental Parameter) method

[0022] When forming the Ni-W layer 4 on the base material 2 during the manufacture of the metal material 1, for the base material 2, for example, the plating bath is a sulfuric acid Ni bath, and sulfuric acid Ni(II) hexahydrate etc. are added to make the sulfuric acid Ni concentration 37 g / L to 69 g / L, the W compound concentration 10 g / L to 50 g / L, the organic acid concentration 50 g / L to 150 g / L, and the current density 1 A / dm 2 ~3 A / dm 2 , and it can be formed by setting the liquid temperature to 70 °C to 80 °C.

[0023] (Outermost layer) From the viewpoint of further reducing transmission loss, as in the embodiment shown in FIG. 2, the plating layer 13 of the metal material 11 preferably includes the outermost layer 15 containing at least one metal selected from the group consisting of Au (gold), Ag (silver), Sn (tin), Pd (palladium), and Cu (copper). In the illustrated example, the outermost layer 15 is formed on the Ni-W layer 14 on the outermost surface side (the upper side in FIG. 2) of the metal material 11. The fact that the outermost layer 15 contains these metals can be confirmed by using an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.).

[0024] In high-frequency components, since the influence of the skin effect is strongly manifested, it is considered that by covering the surface of the metal material 11 with the above-described outermost layer 15 having excellent conductivity, the conductive loss in the transmission loss is reduced.

[0025] The thickness of the outermost layer 15 may be 0.005 μm to 5 μm. If the thickness of the outermost layer 15 is too thin, there is a possibility that the transmission loss cannot be reduced so much. If it is too thick, there is a concern that there is no change in the transmission loss or the cost of precious metals increases.

[0026] For example, when the outermost layer 15 is formed by Au-Co plating (hard plating), the Au content of the outermost layer 15 may be about 99.7% by mass. Alternatively, when the outermost layer 15 is formed by pure Au plating (soft plating), the Au content of the outermost layer 15 may be almost 100% by mass. Alternatively, when the outermost layer 15 contains another metal (Ag, Sn, Pd, or Cu), the content of the metal may be almost 100% by mass. The metal content of the outermost layer 15 can be measured by using an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.). For example, an outermost layer 15 further containing Co such as Au-Co may be formed. It is also possible to form two or more outermost layers of different materials.

[0027] When manufacturing the metal material 11, in order to form the outermost layer 15, plating can be performed on the substrate 12 having the Ni-W layer 14 using an appropriate plating solution according to the material of the outermost layer 15. As the plating solution, for example, in the case of the outermost layer 15 containing Ag, Silverex Bright HS manufactured by EEJA or the like can be preferably used, and in the case of the outermost layer 15 containing Au, a hard Au plating solution or the like can be preferably used. For example, in Ag plating, the current density may be 5 A / dm 2 ~25 A / dm 2 , and the solution temperature may be 30°C to 60°C. Also, for example, in Au plating, the current density may be 5 A / dm 2 ~60 A / dm 2 , and the solution temperature may be 50°C to 60°C.

[0028] (Transmission Loss) The above metal material 1 has a small transmission loss. Preferably, the absolute value of the transmission loss when a current with a frequency of 10 GHz is passed is 4 dB or less. The transmission loss is often measured as a negative value, and the smaller the absolute value and the closer it is to zero, the smaller the transmission loss, and it can be said that it is desirable as a metal material for high-frequency components.

[0029] The transmission loss of the metal material 1 can be measured using a network analyzer. More specifically, as shown in FIG. 3, as a sample to be set in the network analyzer, a microstrip line is used in which a dielectric layer is provided on a copper foil, and further, a copper wiring with a plating layer formed around it is provided on the dielectric layer. To fabricate this sample, a metal foil made of the material of the base material is joined to each of the two surfaces of the dielectric layer by a thermal press at 300 °C, and then, one side of the metal foil is used as wiring by circuit etching, and plating corresponding to the plating layer is applied around the wiring. The wiring corresponds to the base material. This sample is set in a network analyzer (N5247A manufactured by Keysight), the passing power and the reflected power of the alternating current flowing through the sample are measured, and from these voltages P1 and P2, the transmission loss can be obtained from the formula: transmission loss = 10×log(P2 / P1). The measurement is performed for 4 microstrip lines of the sample, and their average value is taken as the transmission loss.

[0030] The metal material 1 described above is used for high-frequency components through which currents at frequencies from 0.1 GHz to 60 GHz, typically from 1 GHz to 60 GHz, more typically from 7 GHz to 30 GHz, and even more typically from 7 to 15 GHz flow. Such high-frequency components include in-vehicle radars, mobile phones such as so-called smartphones, connectors, switches, shields, antennas, etc. mounted on other communication devices.

[0031] According to the metal material 1, by having the above-described configuration, the transmission loss in such high-frequency components can be effectively reduced.

Example

[0032] Next, since the effects of the above-described metal material were confirmed by tests, they will be described below. However, the description here is for illustrative purposes only and is not intended to be limited thereto.

[0033] (Test Example 1) For each of the metal materials with matte Ni plating, Ni-P plating, and Ni-W plating on the substrate, the transmission loss was measured using a network analyzer (N5247A manufactured by Keysight).

[0034] In the fabrication of the microstrip line, which is the sample to be set on the network analyzer, 50-μm LCP resin was used as the dielectric layer, and 12-μm oxygen-free copper foil was used as the metal foil. The oxygen-free copper foil was etched to form a wiring with a width of 124 μm. As the plating applied to this wiring, for matte Ni plating, a nickel sulfamate plating solution was used, with a current density of 10 A / dm 2 and a bath temperature of 60°C. As a result, a Ni layer was formed around the wiring. For Ni-P plating, a Ni sulfate bath was used as the plating bath, with nickel(II) sulfate hexahydrate: 250 g / L, phosphorous acid: 82 g / L, a current density of 10 A / dm 2 and a temperature of 60°C. As a result, a Ni-P layer with a P content of 12 mass% was formed around the wiring. For Ni-W plating, using Nibofram E manufactured by World Metal Co., Ltd., the bath was prepared so that the nickel sulfate was 46 g / L, the W compound was 30 g / L, and the organic acid was 100 g / L, with a current density of 2.5 A / dm 2 and a temperature of 75°C. As a result, a Ni-W layer with a W content of 42 mass% was formed around the wiring. The Ni layer and the Ni-P layer each had a thickness of 2.0 μm, and the Ni-W layer had a thickness of 1.0 μm.

[0035] For each of the samples with matte Ni plating, Ni-P plating, and Ni-W plating, they were set on the network analyzer, and the transmission loss was measured by the method described above. The results are shown in FIGS. 4 and 5. FIG. 4 shows the frequency in decimal, and FIG. 5 shows the frequency in logarithm.

[0036] As can be seen from Figure 4, for the sample plated with Ni-P, the absolute value of the transmission loss is smaller than that of the sample plated with Ni at frequencies below about 15 GHz. For the sample plated with Ni-W, the absolute value of the transmission loss is smaller than that of the sample plated with Ni over the entire frequency range. Also, as can be seen from Figure 5, for the sample plated with Ni-W, the absolute value of the transmission loss is smaller than that of the sample plated with Ni even in the relatively low high-frequency range of 0.1 GHz to 1 GHz.

[0037] (Test Example 2) For the sample of the metal material with a topmost layer formed by plating 0.3 μm of Ag or Au on the Ni layer of the sample of Test Example 1, the transmission loss was measured in the same manner as in Test Example 1. The results are shown in Figure 6.

[0038] Note that for Ag plating, Silverex Bright HS manufactured by EEJA was used, with a current density of 10 A / dm 2 and a bath temperature of 60°C. For Au plating, a hard Au plating solution was used, with a current density of 10 A / dm 2 and a bath temperature of 60°C.

[0039] As can be seen from Figure 6, by providing the topmost layer, there is a tendency for the absolute value of the transmission loss to decrease. This is presumably because in the high-frequency region, the influence of the skin effect is strongly manifested, and when the topmost layer is coated with a noble metal with high conductivity, the conductive loss in the transmission loss becomes smaller. Therefore, Ag, which has a higher conductivity than Au, has a lower transmission loss. Figure 6 shows data for the case where the topmost layer is formed on the Ni layer, but in principle, the same results are considered to be obtained even if the Ni layer is replaced with a Ni-W layer.

[0040] (Test Example 3) Figure 7 shows SIM, TEM, and diffraction images of a metal material in which a Ni-W plating layer is formed by plating an oxygen-free copper (C1020) substrate with Ni-W. The TEM and diffraction images were obtained by processing a cross section with a FIB-SIM (SMI3050SE, Hitachi High-Technologies Corporation) and observing the cross section with a TEM (JEM-2100F, JEOL Ltd.).

[0041] As shown in Figure 7, the SIM image does not clearly show a crystalline state, but the TEM image shows a crystal lattice. In addition, concentric diffraction rings were confirmed by electron diffraction. From this, it is assumed that the Ni-W layer is in a fine polycrystalline state.

[0042] Furthermore, continuous point analysis (line analysis) was performed by TEM-EDX using JEM-2100F manufactured by JEOL Ltd., and the results shown in Figure 8 were obtained. Figure 8 shows that the W co-deposition rate is approximately 42 mass%, and is stable from the initial stage of plating.

[0043] The above suggests that the aforementioned metal material can effectively reduce the transmission loss of internal signals when used in high-frequency components through which internal signals of a certain high frequency flow.

Explanation of symbols

[0044] 1, 11 Metal material 2, 12 Base material 3, 13 Plating layer 4, 14 Ni-W layer 15 Outermost layer

Claims

1. A metal material having a substrate and a plating layer formed on the substrate, the plating layer includes a Ni-W layer containing Ni and W, A metal material used in high frequency components through which currents with frequencies above 0.1 GHz flow.

2. 2. The metallic material according to claim 1, wherein the W content of the Ni--W layer is 30% by mass to 60% by mass.

3. 3. The metallic material according to claim 1, wherein the Ni--W layer has a thickness of 1 μm to 6 μm.

4. 3. The metallic material according to claim 1, wherein the plating layer includes an outermost layer containing at least one metal selected from the group consisting of Au, Ag, Sn, Pd, and Cu.

5. 3. The metallic material according to claim 1, wherein the absolute value of the transmission loss when a current having a frequency of 10 GHz is passed through the metallic material is 4 dB or less.

6. 3. The metallic material according to claim 1, which is used in a high-frequency part through which a current having a frequency of 60 GHz or less flows.

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