Shielding Materials

Abstract

To provide a shield member in which a plated layer provided on a die-cast member containing zinc does not easily swell or peel off even at high temperatures.SOLUTION: A shield member includes a die cast member and a plating layer provided on the surface of the die cast member, and the die cast member contains zinc, the plating layer includes a third layer provided on the outermost surface of the plating layer, the third layer is made of pure tin, and the thickness of the third layer is less than 5 μm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a shield member. [Background technology]

[0002] Patent Document 1 discloses a shielding cage with a die-cast metal section made of a zinc alloy and plated with layers of copper, nickel, and tin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2007-527095 Summary of the Invention [Problem to be solved by the invention]

[0004] When a plating layer is formed on a die-cast member containing zinc, the plating layer may swell or peel off at high temperatures.

[0005] An object of the present disclosure is to provide a shielding member in which a plating layer provided on a zinc-containing die-cast member is unlikely to swell or peel off even at high temperatures. [Means for solving the problem]

[0006] The first shield member of the present disclosure comprises: A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a third layer provided on an outermost surface of the plating layer, the third layer is made of pure tin; The third layer has a thickness of less than 5 μm.

[0007] The second shield member of the present disclosure includes: A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer comprises at least one of a first layer, a second layer, and a third layer; The first layer, the second layer, and the third layer are provided in this order from the die-cast member side. 、 the first layer comprises copper; the second layer comprises nickel; the third layer is made of pure tin; The third layer has a thickness of not less than 0 μm and less than 3 μm. Effect of the Invention

[0008] In the shielding member of the present disclosure, the plating layer provided on the zinc-containing die-cast member is unlikely to swell or peel off even at high temperatures. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a shielding member according to a first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of the shielding member of the second embodiment. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing another example of the shielding member according to the second embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a shielding member according to a third embodiment. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing an example of the shielding member according to the fourth embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing another example of the shielding member according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described.

[0011] (1) A shield member according to a first embodiment of the present disclosure, A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a third layer provided on an outermost surface of the plating layer, the third layer is made of pure tin; The third layer has a thickness of less than 5 μm.

[0012] The state of the shielding member in (1) is the state before it is exposed to high temperatures. In the shielding member of the present disclosure, the thickness of the third layer satisfies a specific range, so that the plating layer is unlikely to swell or peel off even at high temperatures.

[0013] (2) In the shield member of the present disclosure described above in (1), The plating layer includes at least one of a first layer and a second layer, The first layer, the second layer, and the third layer are provided in this order from the die-cast member side. 、 the first layer being made of pure copper; The second layer may consist of pure nickel.

[0014] In the shielding member of (2), the electrical conductivity of the shielding member is easily ensured, and in the shielding member of (2), the solderability is easily ensured.

[0015] (3) In the shield member of the present disclosure described above in (2), the plating layer includes a second layer and a fourth layer provided between the second layer and the third layer, The fourth layer may be made of pure copper.

[0016] When the second layer and the third layer are in contact with each other, the nickel in the second layer and the tin in the third layer are easily alloyed at high temperatures. When the alloying occurs, the thickness of the third layer made of pure tin becomes thinner. In the shielding member (3), the fourth layer is provided between the second layer and the third layer, so that the nickel in the second layer and the tin in the third layer are prevented from being alloyed. Although the copper in the fourth layer and the tin in the third layer are easily alloyed at high temperatures, copper is more difficult to alloy with tin than nickel. Therefore, the fourth layer is provided between the second layer and the third layer, so that the thickness of the third layer is more easily prevented from being thinned at high temperatures compared to when the second layer and the third layer are in contact with each other.

[0017] (4) In the shield member of the present disclosure described above in (1) to (3), The third layer may have a thickness of 1 μm or more.

[0018] In the shielding member of (4), the electrical conductivity of the shielding member is easily ensured, and in the shielding member of (4), the solder wettability is easily ensured.

[0019] (5) A shield member according to a second embodiment of the present disclosure, A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer comprises at least one of a first layer, a second layer, and a third layer; The first layer, the second layer, and the third layer are provided in this order from the die-cast member side. 、 the first layer comprises copper; the second layer comprises nickel; the third layer is made of pure tin; The third layer has a thickness of not less than 0 μm and less than 3 μm.

[0020] The state of the shielding member in (5) is the state after it has been exposed to high temperatures. In the shielding member of the present disclosure, the thickness of the third layer satisfies a specific range, so that the plating layer is unlikely to swell or peel off even at high temperatures.

[0021] (6) In the shield member of the present disclosure described above in (5), the plating layer includes the first layer and the second layer, The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; The second layer is a second alloy layer comprising tin and nickel; a second pure metal layer made of pure nickel; the second pure metal layer is disposed directly on the first pure metal layer, The second alloy layer may be disposed directly on the second pure metal layer.

[0022] The shielding material (6) is formed by exposing the shielding material (2) to high temperatures.

[0023] When the die-cast member and the first layer are in contact with each other, the zinc in the die-cast member and the copper in the first layer can be alloyed at high temperatures. The alloying of zinc and copper forms a first alloy layer as part of the first layer directly on the die-cast member. When the zinc and copper are alloyed, voids can be generated between the die-cast member and the first alloy layer. These voids can cause the plating layer to peel off. By making the thickness of the third layer satisfy the specific range, voids are unlikely to be generated and the plating layer is unlikely to peel off even if the first alloy layer is formed at high temperatures.

[0024] When the second layer and the third layer are in contact with each other, the nickel in the second layer and the tin in the third layer may be alloyed at high temperatures. The nickel and tin are alloyed to form a second alloy layer as part of the second layer. When the nickel and tin are alloyed, the tin may be dissolved by high temperatures. This dissolution of the tin may cause the tin to aggregate and solidify. When the thickness of the third layer satisfies the specific range, the tin in the third layer is prevented from dissolving, agglomerating, and solidifying at high temperatures, and the plating layer is less likely to swell. When the shielding member (2) is exposed to high temperatures, the thickness of the third layer may become 0 μm.

[0025] (7) In the shield member of the present disclosure described above in (5), the plating layer includes the first layer and the second layer, the first layer is an alloy layer containing zinc and copper, The second layer is a second alloy layer comprising tin and nickel; a second pure metal layer made of pure nickel; the second pure metal layer is disposed directly on the first layer, The second alloy layer may be disposed directly on the second pure metal layer.

[0026] The shielding member (7) has the same effect as the shielding member (6). In the shielding member (7), a first alloy layer is formed as a first layer directly on the die-cast member.

[0027] (8) In the shield member of the present disclosure described above in (5), the plating layer includes the first layer, the second layer, and a fourth layer provided directly on the second layer; The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; the second layer comprises a pure metal layer made of pure nickel; The fourth layer may be an alloy layer including tin and copper.

[0028] The shielding material (8) is formed by exposing the shielding material (3) to high temperatures.

[0029] When the die-cast member and the first layer are in contact with each other, the zinc in the die-cast member and the copper in the first layer can be alloyed at high temperatures. The alloying of zinc and copper forms a first alloy layer as part of the first layer directly on the die-cast member. When the zinc and copper are alloyed, voids can be generated between the die-cast member and the first alloy layer. These voids can cause the plating layer to peel off. By making the thickness of the third layer satisfy the specific range, voids are unlikely to be generated and the plating layer is unlikely to peel off even if the first alloy layer is formed at high temperatures.

[0030] By providing the fourth layer between the second layer and the third layer, it is possible to suppress alloying of the nickel in the second layer and the tin in the third layer at high temperatures. Nickel and tin are easily alloyed, and when alloyed, the thickness of the third layer becomes thin. By providing the fourth layer between the second layer and the third layer, it is easier to suppress the thickness of the third layer from becoming thin at high temperatures compared to when the second layer and the third layer are in contact with each other. At high temperatures, the copper in the fourth layer and the tin in the third layer are alloyed. When the copper and the tin are alloyed, the tin can be dissolved by the high temperature. This dissolution of the tin can cause the tin to coagulate and solidify. By the thickness of the third layer satisfying the specific range, the tin in the third layer is suppressed from dissolving, coagulating, and solidifying at high temperatures, and the plating layer is less likely to swell. When the shielding member (3) is exposed to high temperatures, the thickness of the third layer can become 0 μm.

[0031] (9) In the shield member of the present disclosure described above in (5), the plating layer includes the first layer, the second layer, and a fourth layer provided directly on the second layer; the first layer is an alloy layer containing zinc and copper, the second layer comprises a pure metal layer made of pure nickel; The fourth layer may be an alloy layer including tin and copper.

[0032] The shielding member (9) has the same effect as the shielding member (8). In the shielding member (9), a first alloy layer is formed as a first layer directly on the die-cast member.

[0033] (10) In the shield member of the present disclosure described above in (5) to (9), The third layer may have a thickness of 0.5 μm or more.

[0034] In the shielding member of (10), the electrical conductivity of the shielding member is easily ensured, and in the shielding member of (10), the solder wettability is easily ensured.

[0035] [Details of the embodiment of the present disclosure] Specific examples of the embodiments of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same objects. In each drawing, for convenience of explanation, some of the configurations may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual ratios. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0036] <Shielding material overview> The shielding member 1 of the embodiment is a member used as a part of a high-frequency connector. One of the features of the shielding member 1 of the embodiment is that a predetermined plating layer 3 is provided on a die-cast member 2 containing zinc, as shown in Fig. 1 to Fig. 6. In the following, the shape and usage of the shielding member 1 will first be described, and then the die-cast member 2 and plating layer 3 constituting the shielding member 1 will be described in detail with reference to Fig. 1 to Fig. 6. Fig. 1 to Fig. 6 show an enlarged schematic view of the plating layer 3 of the shielding member 1 and the vicinity of the plating layer 3.

[0037] <Shield material shape> The shielding member 1 is incorporated as a part of the high-frequency connector. The high-frequency connector is connected to the terminal of the shielded electric wire. A known configuration can be used for the basic configuration of the high-frequency connector. The high-frequency connector has a plurality of terminals. Each terminal is, for example, an L-shaped rod-shaped piece. The shielding member 1 has a shape and size that can cover the plurality of terminals. The shielding member 1 covers, for example, substantially the entirety of the plurality of terminals. A dielectric member is disposed on the outer periphery of each terminal. Each dielectric member ensures electrical insulation between the terminals and between each terminal and the shielding member 1.

[0038] The high-frequency connector further includes a housing. The housing is connected to, for example, the rear end of the shielding member 1. First ends of the terminals extend into the housing and are connected to the conductors of the shielded electric wires inside the housing. A wall portion of the shielding member 1 facing the housing, in this example the rear wall portion, is provided with a plurality of holes through which the first ends of the terminals pass. Second ends of the terminals are connected to the circuit board. A wall portion of the shielding member 1 facing the circuit board, in this example the lower wall portion, is provided with a plurality of holes through which the second ends of the terminals pass.

[0039] The main part of the shield member 1 is composed of a die-cast member 2 shown in Figures 1 to 6. The die-cast member 2 is produced by injecting molten metal, i.e., molten metal, into a die under pressure and then cooling it. The die-cast member 2 can be produced with high precision even if it has a complex shape.

[0040] <How shielding materials are used> The shielding member 1 is exposed to high temperatures. The high temperatures are, for example, 60°C or higher and 260°C or lower. For example, when a terminal of a high-frequency connector is reflow soldered to a circuit board, the shielding member 1 is exposed to high temperatures. When reflow soldering is performed, the shielding member 1 is exposed to temperatures, for example, 200°C or higher and 260°C or lower. In addition, when the high-frequency connector is mounted in an automobile, the shielding member 1 may be exposed to high temperatures due to thermal load caused by the operating environment, such as the engine. The high-frequency connector is used, for example, for high-speed wired communication in an automobile. When the high-frequency connector is mounted in an automobile, the shielding member 1 is exposed to temperatures, for example, 60°C or higher and 130°C or lower.

[0041] <Die-casting components> The die-cast member 2 constitutes a main portion of the shield member 1. The die-cast member 2 forms the shape of the shield member 1.

[0042] The die-cast member 2 is made of pure zinc or a zinc alloy. The die-cast member 2 containing zinc has high electrical conductivity. In a zinc alloy, the most abundant element among the elements constituting the alloy is zinc (Zn). In addition to zinc, the zinc alloy contains at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), iron (Fe), lead (Pb), cadmium (Cd), and tin (Sn). The die-cast member 2 of this example is made of a zinc alloy containing aluminum and magnesium.

[0043] <Plating layer> 1 to 6, the plating layer 3 is provided on the surface of the die-cast member 2. The plating layer 3 is provided to increase the electrical conductivity of the shielding member 1. The plating layer 3 is in a different state immediately after plating and after being exposed to high temperatures.

[0044] <Embodiment 1> The plating layer 3 of the first embodiment will be described with reference to FIG. 1. The state of the plating layer 3 of the first embodiment is the state before being exposed to high temperature. The plating layer 3 of the first embodiment includes a third layer 33 provided on the outermost surface of the plating layer 3. The plating layer 3 may include at least one of a first layer 31 and a second layer 32. The plating layer 3 of the first embodiment includes a first layer 31, a second layer 32, and a third layer 33 provided in this order from the die-cast member 2 side. Each of the first layer 31, the second layer 32, and the third layer 33 is composed of a pure metal layer.

[0045] [First layer] The first layer 31 is a first pure metal layer 311 made of pure copper. Pure copper has a copper (Cu) content of 99.95% by mass or more. The first layer 31 is provided on the innermost side of the plating layer 3, i.e., directly on the die-cast member 2. The first layer 31 is a base layer for providing a third layer 33, which will be described later, on the die-cast member 2.

[0046] The thickness of the first layer 31 is, for example, 10 μm or more and 15 μm or less. When the thickness of the first layer 31 is 10 μm or more, the third layer 33 is reliably provided as the plating layer 3. When the thickness of the first layer 31 is 15 μm or less, the plating layer 3 is prevented from becoming thick. When the thickness of the first layer 31 is 15 μm or less, the time required for forming the plating layer 3 is prevented from increasing. The thickness of the first layer 31 is preferably 12 μm or more and 15 μm or less. The thickness of the first layer 31 can be measured using a fluorescent X-ray thickness meter. The thickness of the first layer 31 is the average value of thicknesses measured at multiple different measurement points on the first layer 31. The number of measurement points is 10 or more, preferably 20 or more, and more preferably 30 or more.

[0047] [Second layer] The second layer 32 is a second pure metal layer 321 made of pure nickel. The content of nickel (Ni) in pure nickel is 99.99 mass% or more. The second layer 32 is provided directly on the first layer 31. The second layer 32 is provided to suppress the diffusion of copper contained in the first layer 31 to the third layer 33 side.

[0048] The thickness of the second layer 32 is, for example, 2 μm or more and 5 μm or less. When the thickness of the second layer 32 is 2 μm or more, the copper contained in the first layer 31 third layer 33 The thickness of the second layer 32 is preferably 4 μm or more and 5 μm or less. The thickness of the second layer 32 can be measured using a fluorescent X-ray thickness gauge, similar to the first layer 31. The thickness of the second layer 32 is the average value of thicknesses measured at a plurality of different measurement points on the second layer 32, similar to the first layer 31.

[0049] [Third layer] The third layer 33 is a pure metal layer made of pure tin. Pure tin has a tin (Sn) content of 99.99 mass% or more. The third layer 33 constitutes the outermost surface of the plating layer 3. The third layer 33 is provided to increase the electrical conductivity of the shielding member 1.

[0050] The thickness of the third layer 33 is less than 5 μm. When the thickness of the third layer 33 is less than 5 μm, swelling or peeling of the plating layer 3 can be suppressed at high temperatures, as shown in the test example described later. The thickness of the third layer 33 is preferably 4 μm or less. The thickness of the third layer 33 is preferably 1 μm or more. When the thickness of the third layer 33 is 1 μm or more, the electrical conductivity of the shielding member 1 is easily ensured. When the thickness of the third layer 33 is 1 μm or more, the solder wettability is easily ensured. The thickness of the third layer 33 is more than 0 μm and less than 5 μm, preferably 1 μm or more and less than 5 μm, more preferably 2 μm or more and 4 μm or less, and particularly preferably 2 μm or more and 3 μm or less. The thickness of the third layer 33 can be measured using a fluorescent X-ray film thickness meter, similar to the first layer 31. The thickness of the third layer 33 is an average value of thicknesses measured at multiple different measurement points on the third layer 33, similar to the first layer 31.

[0051] The plating layer 3 may include only the third layer 33. The plating layer 3 may include the first layer 31 and the third layer 33, and may not include the second layer 32. The plating layer 3 may include the second layer 32 and the third layer 33, and may not include the first layer 31.

[0052] <Embodiment 2> The plating layer 3 of the second embodiment will be described with reference to FIG. 2 and FIG. 3. The plating layer 3 of the second embodiment is in a state after the shielding member 1 having the plating layer 3 of the first embodiment is exposed to high temperature. The plating layer 3 of the second embodiment includes at least one of a first layer 31, a second layer 32, and a third layer 33. The plating layer 3 of the second embodiment includes the first layer 31, the second layer 32, and the third layer 33, which are provided in this order from the die-casting member 2 side. The plating layer 3 of the second embodiment is different from the plating layer 3 of the first embodiment in that the first layer 31 includes a first alloy layer 312 and the second layer 32 includes a second alloy layer 322. The first layer 31 may further include a first pure metal layer 311 as shown in FIG. 2. In the plating layer 3 shown in FIG. 3, the first layer 31 is composed of a first alloy layer 312. The difference between FIG. 2 and FIG. 3 is whether the first layer 31 includes a first pure metal layer 311 or not.

[0053] [First layer] The first layer 31 includes a first alloy layer 312 provided directly on the die-cast member 2. The first alloy layer 312 contains zinc and copper. The first alloy layer 312 is a layer formed by alloying the zinc contained in the die-cast member 2 and the copper contained in the first layer 31 in the plating layer 3 of the embodiment 1 at high temperature. Depending on the thickness of the first layer 31 in the plating layer 3 of the embodiment 1 and the high temperature conditions, a first pure metal layer 311 shown in FIG. 2 is provided as the first layer 31. The first pure metal layer 311 is made of pure copper. The first pure metal layer 311 is a layer in which the copper contained in the first layer 31 in the plating layer 3 of the embodiment 1 remains without being alloyed. The first pure metal layer 311 is provided directly on the first alloy layer 312.

[0054] The higher the temperature at high temperature or the longer the holding time at high temperature, the thicker the first alloy layer 312 and the thinner the first pure metal layer 311. Depending on the conditions at high temperature, the entire first layer 31 in the plating layer 3 of embodiment 1 may become the first alloy layer 312 as shown in FIG.

[0055] When the first alloy layer 312 and the first pure metal layer 311 are provided as in the first layer 31 shown in Fig. 2, the thickness of the first alloy layer 312 is, for example, 0.5 µm or more and 2 µm or less. It is preferable that the thickness of the first alloy layer 312 is thin. The thickness of the first alloy layer 312 is preferably 0.5 µm or more and 1 µm or less.

[0056] The thickness of the first pure metal layer 311 is, for example, 5 μm or more and 15 μm or less. When the thickness of the first pure metal layer 311 is 5 μm or more, it is easy to suppress zinc from diffusing to the second layer 32. When the thickness of the first pure metal layer 311 is 15 μm or less, the first layer 31 is suppressed from becoming thick. The thickness of the first pure metal layer 311 is preferably 10 μm or more and 15 μm or less.

[0057] When the first layer 31 is composed of the first alloy layer 312, like the first layer 31 shown in FIG. 3, the thickness of the first alloy layer 312 is, for example, not less than 10 μm and not more than 15 μm.

[0058] When the first alloy layer 312 and the first pure metal layer 311 are provided as in the first layer 31 shown in FIG. 2, the thicknesses of the first alloy layer 312 and the first pure metal layer 311 can be measured using a scanning electron microscope as follows. First, any cross section along the lamination direction of the die-cast member 2 and the plating layer 3 in the shield member 1 is taken. The number of cross sections may be one or more. A plurality of backscattered electron images are taken from one or more cross sections. If the number of cross sections is one, a plurality of backscattered electron images are taken from the cross section. If the number of cross sections is multiple, one or a plurality of backscattered electron images are taken from each cross section. The total number of backscattered electron images is, for example, three. In each backscattered electron image, the thickness of the first alloy layer 312 or the first pure metal layer 311 in the first layer 31 is measured. The thickness of the first alloy layer 312 is the average value of thicknesses measured at a plurality of different measurement points in the first alloy layer 312. The thickness of the first pure metal layer 311 is the average value of thicknesses measured at a plurality of different measurement points in the first pure metal layer 311. The number of measurement points is 10 or more, preferably 20 or more, and more preferably 30 or more.

[0059] [Second layer] The second layer 32 includes a second alloy layer 322 and a second pure metal layer 321, as shown in FIGS.

[0060] The second alloy layer 322 is provided directly under the third layer 33. The second alloy layer 322 contains tin and nickel. The second alloy layer 322 is a layer formed by alloying the nickel contained in the second layer 32 and the tin contained in the third layer 33 in the plating layer 3 of the embodiment 1 at high temperatures. Depending on the conditions In the first embodiment, the second layer 32 in the plating layer 3 is alloyed throughout. There is. The second pure metal layer 321 is made of pure nickel. The second pure metal layer 321 is provided directly below the second alloy layer 322. The second pure metal layer 321 is provided directly above the first layer 31, and the second alloy layer 322 is provided directly above the second pure metal layer 321.

[0061] The thickness of the second alloy layer 322 is, for example, 0.5 μm or more and 1.5 μm or less. When the thickness of the second alloy layer 322 is 0.5 μm or more, it is easy to suppress tin from diffusing further inward. When the thickness of the second alloy layer 322 is 1.5 μm or less, the thickness of the third layer 33 satisfies the specific range. It is preferable that the thickness of the second alloy layer 322 is thin. The thickness of the second alloy layer 322 is preferably 0.5 μm or more and 1 μm or less.

[0062] The thickness of second pure metal layer 321 is, for example, 1 μm or more and 5 μm or less. When the thickness of second pure metal layer 321 is 1 μm or more, it is easy to suppress the diffusion of zinc and copper contained in first layer 31 to third layer 33. When the thickness of second pure metal layer 321 is 1 μm or more, the thickness of third layer 33 satisfies a specific range. When the thickness of second pure metal layer 321 is 5 μm or less, thickening of second layer 32 is suppressed. The thickness of second pure metal layer 321 is preferably 2 μm or more and 5 μm or less.

[0063] The thicknesses of the second alloy layer 322 and the second pure metal layer 321 can be measured using a scanning electron microscope, similar to the first alloy layer 312 and the first pure metal layer 311. The thickness of the second alloy layer 322, similar to the first alloy layer 312, is the average value of thicknesses measured at multiple different measurement points on the second alloy layer 322. The thickness of the second pure metal layer 321, similar to the first pure metal layer 311, is the average value of thicknesses measured at multiple different measurement points on the second pure metal layer 321.

[0064] [Third layer] The third layer 33 is a pure metal layer made of pure tin.

[0065] The thickness of the third layer 33 is less than 3 μm. As shown in the test example described later, the thickness of the third layer 33 is less than 3 μm, and therefore, even at high temperatures, the swelling and peeling of the plating layer 3 can be suppressed. The thickness of the third layer 33 is thinner than that of the third layer 33 in the plating layer 3 of the first embodiment. The reason for the thinner thickness is that, as described above, nickel contained in the second layer 32 and tin contained in the third layer 33 in the plating layer 3 of the first embodiment are alloyed at high temperatures. When exposed to high temperatures, the third layer 33 in the plating layer 3 of the first embodiment may have a thickness of 0 μm. That is, the thickness of the third layer 33 after exposure to high temperatures is 0 μm or more and less than 3 μm. The thickness of the third layer 33 is preferably 0.5 μm or more and less than 3 μm. The thickness of the third layer 33 can be measured using a fluorescent X-ray thickness gauge, as in the third layer 33 of the first embodiment. The thickness of the third layer 33 is an average value of thicknesses measured at multiple different measurement points in the third layer 33, as in the third layer 33 of the first embodiment.

[0066] Third Embodiment The plating layer 3 of the third embodiment will be described with reference to FIG. 4. The plating layer 3 of the third embodiment includes a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34. The fourth layer 34 is provided between the second layer 32 and the third layer 33. The plating layer 3 of the third embodiment is in a state before being exposed to high temperature. Each of the first layer 31, the second layer 32, the third layer 33, and the fourth layer 34 is composed of a pure metal layer. The plating layer 3 of the third embodiment is different from the plating layer 3 of the first embodiment in that it includes the fourth layer 34. The configurations of the first layer 31, the second layer 32, and the third layer 33 in the plating layer 3 of the third embodiment are the same as those of the first embodiment. The fourth layer 34 will be described below.

[0067] [Fourth layer] The fourth layer 34 is a fourth pure metal layer 341 made of pure copper. The fourth layer 34 is provided between the second layer 32 and the third layer 33. The fourth layer 34 is provided directly below the third layer 33. The fourth layer 34 is provided to suppress the diffusion of nickel contained in the second layer 32 toward the third layer 33. Although copper and tin are easily alloyed, copper is more difficult to alloy with tin than nickel.

[0068] The thickness of the fourth layer 34 is, for example, 0.1 μm or more and 0.4 μm or less. When the thickness of the fourth layer 34 is 0.1 μm or more, the copper contained in the fourth layer 34 and the tin contained in the third layer 33 are alloyed during reflow treatment. This alloying makes it easy to suppress the nickel contained in the second layer 32 from diffusing to the third layer 33 side. When the thickness of the fourth layer 34 is 0.4 μm or less, the copper contained in the fourth layer 34 and the tin contained in the third layer 33 are suppressed from being excessively alloyed. The thickness of the fourth layer 34 is preferably 0.2 μm or more and 0.3 μm or less. The thickness of the fourth layer 34 can be measured using a scanning electron microscope, similar to the first alloy layer 312 and the first pure metal layer 311 in the second embodiment. The thickness of the fourth layer 34 is an average value of thicknesses measured at a plurality of different measurement points in the fourth layer 34.

[0069] <Fourth embodiment> The plating layer 3 of the fourth embodiment will be described with reference to Figs. 5 and 6. The plating layer 3 of the fourth embodiment is in a state after the shielding member 1 having the plating layer 3 of the third embodiment is exposed to high temperature. The plating layer 3 of the fourth embodiment includes a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34. The plating layer 3 of the fourth embodiment is different from the plating layer 3 of the third embodiment in that the first layer 31 includes a first alloy layer 312 and the fourth layer 34 includes a fourth alloy layer 342. The first layer 31 may further include a first pure metal layer 311 as shown in Fig. 5. In the plating layer 3 shown in Fig. 6, the first layer 31 includes a first alloy layer 312. The difference between Figs. 5 and 6 is whether the first layer 31 includes the first pure metal layer 311 or not. The plating layer 3 of the fourth embodiment can also be produced by intentionally subjecting the shielding member 1 having the plating layer 3 of the third embodiment to a heat treatment.

[0070] [First layer] The first layer 31 includes a first alloy layer 312 provided directly on the die-cast member 2. The first alloy layer 312 contains zinc and copper. The first alloy layer 312 is a layer formed by alloying the zinc contained in the die-cast member 2 and the copper contained in the first layer 31 in the plating layer 3 of the third embodiment at high temperature. Depending on the thickness of the first layer 31 in the plating layer 3 of the third embodiment and the conditions at high temperature, a first pure metal layer 311 shown in FIG. 5 is provided as the first layer 31. The first pure metal layer 311 is made of pure copper. The first pure metal layer 311 is a layer in which the copper contained in the first layer 31 in the plating layer 3 of the third embodiment remains without being alloyed. The first pure metal layer 311 is provided directly on the first alloy layer 312. The higher the temperature at high temperature or the longer the holding time at high temperature, the thicker the first alloy layer 312 becomes, and the thinner the first pure metal layer 311 becomes relatively. Depending on the conditions under high temperature, the entire first layer 31 in the plating layer 3 of the embodiment 3 may become the first alloy layer 312, as shown in Fig. 6. The configuration of the first layer 31 in the plating layer 3 of the embodiment 4 is similar to that of the embodiment 2.

[0071] [Second layer] 5 and 6, the second layer 32 includes a second pure metal layer 321. The second layer 32 may include a second alloy layer (not shown). The second alloy layer is provided directly on the second pure metal layer 321.

[0072] The thickness of second pure metal layer 321 is, for example, 2 μm or more and 5 μm or less. When the thickness of second pure metal layer 321 is 2 μm or more, it is easy to suppress the zinc and copper contained in first layer 31 from diffusing to third layer 33. When the thickness of second pure metal layer 321 is 5 μm or less, the thickness of third layer 33 satisfies a specific range. The thickness of second pure metal layer 321 is preferably 4 μm or more and 5 μm or less.

[0073] The second alloy layer (not shown) contains tin, copper, and nickel. The second alloy layer is a layer formed by alloying tin contained in the third layer 33, copper contained in the fourth layer 34, and nickel contained in the second layer 32 of the plating layer 3 of embodiment 3 at high temperature. Even when exposed to high temperature, the second layer 32 of the plating layer 3 of embodiment 3 is not alloyed throughout. The thickness of the second alloy layer is, for example, 5 μm or less.

[0074] [Fourth layer] The fourth layer 34 is provided between the second layer 32 and the third layer 33. The fourth layer 34 is provided directly below the third layer 33. The fourth layer 34 is a fourth alloy layer 342 containing tin and copper. The fourth layer 34 is a layer formed by alloying the copper contained in the fourth layer 34 and the tin contained in the third layer 33 in the plating layer 3 of embodiment 3 at high temperature. When exposed to high temperature, the fourth layer 34 in the plating layer 3 of embodiment 3 is alloyed throughout.

[0075] The thickness of the fourth layer 34 is, for example, 0.1 μm or more and 0.4 μm or less. When the thickness of the fourth layer 34 is 0.1 μm or more, it is easy to suppress the nickel contained in the second layer 32 from diffusing toward the third layer 33 side. When the thickness of the fourth layer 34 is 0.4 μm or less, the plating layer 3 is suppressed from becoming thick. The thickness of the fourth layer 34 is preferably 0.2 μm or more and 0.3 μm or less. The thickness of the fourth layer 34 can be measured using a scanning electron microscope, similarly to the fourth layer 34 of the third embodiment. The thickness of the fourth layer 34 is an average value of thicknesses measured at a plurality of different measurement points on the fourth layer 34.

[0076] [Third layer] The third layer 33 is a pure metal layer made of pure tin.

[0077] The thickness of the third layer 33 is less than 3 μm. As shown in the test example described later, the thickness of the third layer 33 is less than 3 μm, and therefore, even at high temperatures, the swelling and peeling of the plating layer 3 can be suppressed. The thickness of the third layer 33 is thinner than that of the third layer 33 in the plating layer 3 of the third embodiment. The reason for the thinner thickness is that, as described above, the copper contained in the fourth layer 34 in the plating layer 3 of the third embodiment and the tin contained in the third layer 33 are alloyed at high temperatures. When exposed to high temperatures, the third layer 33 in the plating layer 3 of the third embodiment may have a thickness of 0 μm. That is, the thickness of the third layer 33 after exposure to high temperatures is 0 μm or more and less than 3 μm. The thickness of the third layer 33 is preferably 0.5 μm or more and less than 3 μm, more preferably 1 μm or more and less than 3 μm, and particularly preferably 2 μm or more and less than 3 μm. The thickness of the third layer 33 can be measured using a fluorescent X-ray thickness gauge, similar to the third layer 33 of the first embodiment. The thickness of the third layer 33 is, like the third layer 33 of the first embodiment, an average value of thicknesses measured at a plurality of different measurement points on the third layer 33 .

[0078] [Test Example 1] In Test Example 1, a shielding member was produced by providing a plating layer on a die-cast member containing zinc. The state of the plating layer after this shielding member was exposed to high temperatures was examined.

[0079] <Sample> A die-cast member of a predetermined shape was prepared. The die-cast member was made of a zinc alloy containing aluminum and magnesium. The die-cast member was plated with a first layer, a second layer, and a third layer, in that order from the die-cast member side. The first layer was made of pure copper. The second layer was made of pure nickel. The third layer was made of pure tin. The thicknesses of the first, second, and third layers are shown in Table 1. If a "0" is written in a cell in Table 1, it indicates that the layer corresponding to that cell was not applied.

[0080] [Table 1]

[0081] Shielding members each having a die-cast member and a plating layer shown in Table 1 were left at a high temperature of 125°C for 120 hours. Samples No. 1-1 to No. 1-9 shown in Table 1 were renamed Samples No. 1-11 to No. 1-19, respectively, after being left at high temperature.

[0082] <Plating layer> The state of the plating layer in samples No. 1-11 to No. 1-19 was examined. As a result, in the samples that had a first layer before being left at high temperature, a first alloy layer was formed directly on the die-cast member as the first layer. The first alloy layer contained zinc and copper. In some samples, a first pure metal layer was formed directly on the first alloy layer as the first layer. The first pure metal layer was made of pure copper. Among the samples that had a second layer before being left at high temperature, in samples No. 1-13, 1-15, and 1-17, a second alloy layer was formed directly below the third layer as the second layer, and a second pure metal layer was formed directly below the second alloy layer as the second layer. The second alloy layer contained tin and nickel. The second pure metal layer was made of pure nickel. In the samples that had a third layer, the third layer was made of pure tin. The thickness of each layer is shown in Table 2. When a "0" is written in a cell in Table 2, it indicates that the layer corresponding to that cell does not exist.

[0083] <Surface observation> The surfaces of the plating layers of Samples No. 1-11 to No. 1-19 were visually observed. The results are shown in Table 2. In the table, A indicates that the plating layer was properly formed without swelling or peeling. In the table, B indicates that the plating layer was swollen or peeled.

[0084] [Table 2]

[0085] As shown in Tables 1 and 2, in samples No. 1-1, 1-2, and 1-3, in which the thickness of the third layer immediately after plating was less than 5 μm, no blistering or peeling occurred in the plating layer. On the other hand, in samples No. 1-4 to 1-9, in which the thickness of the third layer immediately after plating was 5 μm or more, blistering and peeling occurred in the plating layer after exposure to high temperature. It is considered that if the thickness of the third layer before exposure to high temperature is thick, the tin contained in the third layer melts, coagulates, and solidifies due to the high temperature, causing the plating layer to blister. In addition, it is considered that the inclusion of zinc in the die-casting member causes voids to occur between the die-casting member and the first alloy layer when the first alloy layer is formed directly on the die-casting member, causing the plating layer to peel off.

[0086] [Test Example 2] In Test Example 2, a shielding member was produced in which a zinc-containing die-cast member was provided with a plating layer different from that in Test Example 1. The state of the plating layer after this shielding member was exposed to high temperatures was examined.

[0087] <Sample> A die-cast member of a predetermined shape was prepared. The die-cast member was made of a zinc alloy containing aluminum and magnesium. The die-cast member was plated with a first layer, a second layer, a fourth layer, and a third layer, in that order from the die-cast member side. The first and fourth layers were made of pure copper. The second layer was made of pure nickel. The third layer was made of pure tin. The thicknesses of the first, second, third, and fourth layers are shown in Table 3. When a "0" is written in a cell in Table 3, it indicates that the layer corresponding to that cell has not been applied.

[0088] [Table 3]

[0089] Shielding members having a die-cast member coated with a plating layer shown in Table 3 were left at a high temperature of 125°C for 120 hours. Samples No. 2-1 to No. 2-7 shown in Table 3 were renamed Samples No. 2-11 to No. 2-17, respectively, after being left at high temperature.

[0090] <Plating layer> The state of the plating layer in the shielding member after exposure to high temperature was examined. As a result, the following alloy layers were formed in the first and fourth layers. As the first layer, a first alloy layer was formed directly on the die-cast member. The first alloy layer contained zinc and copper. As the first layer, a first pure metal layer was formed directly on the first alloy layer. The first pure metal layer was made of pure copper. As the second layer, a second pure metal layer was formed. The second pure metal layer was made of pure nickel. As the second layer, a second alloy layer was formed directly on the second pure metal layer. The second alloy layer contained tin, copper, and nickel. In the sample with the third layer, the third layer was made of pure tin. As the fourth layer, an alloy layer containing tin and copper was formed. When "0" is written in a cell in Table 4, it indicates that the layer corresponding to that cell does not exist.

[0091] <Surface observation> The surface of the plating layer on the shielding member after exposure to high temperatures was visually observed. The results are shown in Table 4. A in the table indicates that the plating layer was properly applied without swelling or peeling. B in the table indicates that the plating layer was swollen or peeled.

[0092] [Table 4]

[0093] As shown in Tables 3 and 4, the thickness of the third layer immediately after plating was less than 5 μm in all samples, so there was no blistering or peeling of the plating layer. In particular, samples No. 2-3, 2-5, and 2-7, which were provided with a fourth layer, had a third layer after being left at high temperature, even though the thickness of the third layer immediately after plating was as thin as 3 μm or less. It is believed that the provision of the fourth layer suppressed alloying of the nickel in the second layer and the tin in the third layer. [Explanation of symbols]

[0094] 1 Shielding material 2. Die-casting parts 3. Plating layer 31 First layer 311 First pure metal layer, 312 First alloy layer 32 Second layer 321 Second pure metal layer, 322 Second alloy layer 33 Third layer 34 Fourth layer 341 Fourth pure metal layer, 342 Fourth alloy layer

Claims

1. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a third layer provided on an outermost surface of the plating layer, the third layer is made of pure tin; The thickness of the third layer is less than 5 μm. Shielding material.

2. The plating layer includes at least one of a first layer and a second layer, the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, the first layer being made of pure copper; 2. The shielding member of claim 1, wherein the second layer is made of pure nickel.

3. the plating layer includes a second layer and a fourth layer provided between the second layer and the third layer, The shielding member according to claim 2 , wherein the fourth layer is made of pure copper.

4. The shielding member according to claim 1 , wherein the third layer has a thickness of 1 μm or more.

5. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; The plating layer includes a first layer and a second layer as essential layers, and a third layer as an optional layer; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; The second layer is a second alloy layer comprising tin and nickel; a second pure metal layer made of pure nickel; the second pure metal layer is disposed directly on the first pure metal layer, the second alloy layer is disposed directly on the second pure metal layer; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

6. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; The plating layer includes a first layer and a second layer as essential layers, and a third layer as an optional layer; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, the first layer is an alloy layer containing zinc and copper, The second layer is a second alloy layer comprising tin and nickel; a second pure metal layer made of pure nickel; the second pure metal layer is disposed directly on the first layer, the second alloy layer is disposed directly on the second pure metal layer; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

7. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a first layer, a second layer, and a fourth layer as essential layers, and a third layer as an optional layer; the first layer, the second layer, the fourth layer, and the third layer are provided in this order from the die-cast member side, The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; the second layer comprises a pure metal layer made of pure nickel; the fourth layer is an alloy layer containing tin and copper and is provided directly on the second layer; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

8. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a first layer, a second layer, and a fourth layer as essential layers, and a third layer as an optional layer; the first layer, the second layer, the fourth layer, and the third layer are provided in this order from the die-cast member side, the first layer is an alloy layer containing zinc and copper, the second layer comprises a pure metal layer made of pure nickel; the fourth layer is an alloy layer containing tin and copper and is provided directly on the second layer; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

9. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer comprises at least one of a first layer, a second layer, and a third layer; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, the first layer comprises copper; the second layer comprises nickel; the third layer is made of pure tin; The thickness of the third layer is 0.5 μm or more and less than 3 μm. Shielding material.

10. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; The plating layer includes a first layer as an essential layer, and a second layer and a third layer as optional layers; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; the second layer comprises nickel; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

11. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; The plating layer includes a first layer and a second layer as essential layers, and a third layer as an optional layer; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, The first layer is a first alloy layer comprising zinc and copper; A first pure metal layer made of pure copper; the first alloy layer is disposed directly on the die-cast member, the first pure metal layer is disposed directly on the first alloy layer; the second layer is an alloy layer containing tin and nickel, the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

12. A die-cast member; A shielding member comprising: a plating layer provided on a surface of the die-casting member, the die-cast member comprises zinc; the plating layer includes a second layer as an essential layer, and a first layer and a third layer as optional layers; the first layer, the second layer, and the third layer are provided in this order from the die-cast member side, the first layer comprises copper; The second layer is a second alloy layer comprising tin and nickel; a second pure metal layer made of pure nickel; The second pure metal layer is provided directly on the die-cast member or directly on the first layer, the second alloy layer is disposed directly on the second pure metal layer; the third layer is made of pure tin; The thickness of the third layer is 0 μm or more and less than 3 μm. Shielding material.

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