Metal components, heat dissipation components, and packages

Abstract

The present invention provides a metal component that suppresses unevenness in the luster of precious metals while maintaining high connection reliability of metal components achieved by using precious metals. [Solution] The base material 10 contains copper and has a plurality of crystal grains. The plating portion 20H1 provided on the surface SM of the base material 10 contains copper at a copper atom concentration lower than that of the base material 10, or substantially contains no copper. The plating portion 20H1 has a first layer 21, a second layer 22, a third layer 23, and a fourth layer 24. The first layer 21 is provided on the surface SM of the base material 10 and has a plurality of crystal grains epitaxially formed on a plurality of crystal grains of the base material 10. The second layer 22 contains nickel and has a plurality of crystal grains formed unoriented on each of the plurality of crystal grains of the first layer 21. The third layer 23 is provided on the second layer 22. The fourth layer 24 is provided on the third layer 23 and contains a precious metal.

Description

Technical Field

[0001] The present invention relates to a metal member, a heat dissipation member, and a package.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-243145 (Patent Document 1) discloses a package for housing a high heat dissipation type electronic component. This package has a heat sink plate, a frame body, and external connection terminals. A cavity for housing an electronic component such as a semiconductor element is formed by the upper surface of the heat sink plate and the inner peripheral side wall surface of the frame body. In this cavity, an electronic component is mounted on the upper surface of the heat sink plate. The electronic component and the external connection terminals are electrically connected by bonding wires. Thus, the attachment of the electronic component to the package is completed. Thereafter, a lid is joined to the package, whereby the electronic component is sealed in the cavity. As the material of the heat sink plate, a material having high thermal conductivity and a thermal expansion coefficient close to that of the material of the frame body is selected. For example, a Cu (copper)-W (tungsten) composite metal plate, a Cu-Mo (molybdenum) composite metal plate, a Cu / Cu-Mo / Cu joined metal plate in which Cu plates are clad on both surfaces of a Cu-Mo-based metal plate, etc. are used. At the time before the electronic component is mounted, a Ni (nickel) plating layer and an Au (gold) plating layer are formed on the metal surface exposed to the outside of the package including the heat sink plate and the external connection terminals.

[0003] As described above, a multilayer plating including a Ni plating layer and an Au plating layer is formed on the surface of the heat sink plate. A portion of the surface of the multilayer plating is the mounting surface on which electronic components will be mounted. Protrusions or foreign objects on the mounting surface can adversely affect the connection reliability of electronic components. Therefore, it is desirable to perform inspections to detect protrusions or foreign objects on the mounting surface. In mass production, it is desirable to perform this inspection by automated visual inspection using a camera. If the mounting surface captured by the camera has excessive unevenness in gloss, the resulting contrast may be mistaken for a protrusion or foreign object. In particular, precious metal plating layers such as the Au plating layer usually have high gloss if they are flat. Therefore, the contrast due to uneven gloss tends to be large.

[0004] International Publication No. 2020 / 217787 (Patent Document 2) discloses a metal member, for example, a heat sink plate. This metal member comprises a metal substrate, a first intermediate plating layer, a second intermediate plating layer, and a noble metal plating layer. The metal substrate has a surface composed of multiple crystal grains. The first intermediate plating layer is formed directly on the multiple crystal grains of the metal substrate, contains Ni element, and is unoriented with respect to each crystal orientation in the multiple crystal grains of the metal substrate. The second intermediate plating layer is formed directly on the first intermediate plating layer. The noble metal plating layer is formed on the second intermediate plating layer. According to this metal member, the first intermediate plating layer, which is unoriented with respect to each crystal orientation in the multiple crystal grains of the metal substrate, is formed on the surface of the metal substrate. As a result, the second intermediate plating layer and the noble metal plating layer formed on the first intermediate plating layer are formed without being affected by the unevenness of the crystal orientation in the crystal grains that make up the surface of the metal substrate. Therefore, uneven growth of the precious metal plating layer, which reflects the unevenness of the crystal orientation in the crystal grains forming the surface of the metal substrate, is prevented. Thus, unevenness in the gloss of the precious metal plating layer can be suppressed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-243145 [Patent Document 2] International Publication No. 2020 / 217787 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The precious metal plating layer forming the surface of the above-mentioned metal component has the function of improving the reliability of the connection of the plated portion to other elements such as the solder layer. On the other hand, further investigation by the inventors has shown that the copper present in the metal substrate is easily penetrated by thermal diffusion through the first intermediate plating layer, which is unoriented with respect to the crystal orientation of the metal substrate. The copper that has penetrated the first intermediate plating layer may further penetrate the second intermediate plating layer and reach the precious metal plating layer. It is thought that this phenomenon may affect the surface properties of the plated portion, potentially reducing the reliability of the connection of the plated portion.

[0007] The following embodiments were conceived to solve the above-mentioned problems, and one of their objectives is to provide a metal component that can suppress unevenness in the luster of precious metals while maintaining high connection reliability of the plated portion by using precious metals. [Means for solving the problem]

[0008] The metal member described in Embodiment 1 comprises a base material having a surface containing copper and a plurality of crystal grains reaching the surface, and a plated portion provided on the surface of the base material, wherein the plated portion contains copper at a copper atom concentration lower than that of the base material, or substantially contains no copper, and the plated portion includes a first layer provided on the surface of the base material and having a plurality of crystal grains epitaxially formed on the plurality of crystal grains of the base material, a second layer provided on the first layer and containing nickel and having a plurality of crystal grains formed unoriented on each of the plurality of crystal grains of the first layer, a third layer provided on the second layer, and a fourth layer provided on the third layer and containing a precious metal.

[0009] The metal member described in embodiment 2 comprises a base material containing copper, having a surface and a plurality of crystal grains reaching the surface, and a plated portion provided on the surface of the base material, wherein the plated portion contains copper at a copper atom concentration lower than that of the base material, or substantially contains no copper, and the plated portion includes a first layer provided on the surface of the base material and having a plurality of crystal grains epitaxially formed on the plurality of crystal grains of the base material, a second layer provided on the first layer and containing nickel and having a plurality of crystal grains formed unoriented on each of the plurality of crystal grains of the first layer, and a fourth layer directly provided on the second layer and containing a precious metal.

[0010] The metal member described in embodiment 3 is the metal member described in embodiment 1, wherein the third layer of the plated portion contains nickel.

[0011] The metal member described in embodiment 4 is the metal member described in embodiment 3, wherein the third layer of the plated portion contains cobalt.

[0012] The metal member described in embodiment 5 is the metal member described in any one of embodiments 1 to 4, wherein the surface of the base material is an unpolished surface.

[0013] The metal member described in embodiment 6 is the metal member described in any one of embodiments 1 to 5, wherein no bailby layer is formed on the surface of the base material.

[0014] The metal member described in Embodiment 7 is the metal member described in Embodiment 1 and any one of Embodiments 3 to 6, wherein the third layer of the plated portion has an average grain size that is larger than the average grain size of the second layer.

[0015] The metal member described in embodiment 8 is the metal member described in any one of embodiments 1 to 7, wherein the first layer of the plated portion contains nickel.

[0016] The heat dissipation member described in embodiment 9 comprises a metal member described in any one of embodiments 1 to 8, wherein the fourth layer of the plated portion of the metal member has a mounting surface on which electronic components are mounted.

[0017] The package described in embodiment 10 comprises the heat dissipation member described in embodiment 9 and a frame provided on the heat dissipation member.

[0018] The package described in embodiment 11 is the package described in embodiment 10, wherein the frame is arranged on the base material in the thickness direction.

[0019] The package described in embodiment 12 is the package described in embodiment 10, wherein the heat dissipation member further comprises a support member that supports the metal member, and the frame is arranged on the support member in the thickness direction. [Effects of the Invention]

[0020] According to the above embodiment 1, firstly, the first layer of the plated portion is epitaxially formed on the surface of the substrate portion. As a result, the grain boundaries of the first layer are formed to roughly correspond to the grain boundaries of the substrate portion. Therefore, it is avoided that the first layer has an excessive number of grain boundaries. As a result, thermal diffusion of the copper of the substrate portion along the grain boundaries of the first layer is suppressed. As a result, the first layer can effectively prevent thermal diffusion of the copper of the substrate portion toward the surface of the plated portion. As a result, it is possible to prevent a decrease in the reliability of the connection of the plated portion to other elements due to thermal diffusion of the copper of the substrate portion toward the surface of the plated portion. Secondly, the second layer of the plated portion has a plurality of crystal grains formed unorientedly on each of the plurality of crystal grains of the first layer. As a result, the fourth layer of the plated portion, separated from the substrate portion by the second layer, is formed without being affected by the unevenness of the crystal orientation of the crystal grains forming the surface of the substrate portion. As a result, uneven growth of the fourth layer reflecting the unevenness of the crystal orientation of the crystal grains forming the surface of the substrate portion is prevented. Therefore, unevenness in the gloss of the fourth layer can be suppressed. As a result, while suppressing unevenness in the gloss of the fourth layer, the high connection reliability of the plated part due to the inclusion of precious metals in the fourth layer can be maintained.

[0021] According to the above-described aspect 2, first, the first layer of the plating portion is epitaxially formed on the surface of the base material portion. As a result, the grain boundaries of the first layer are formed approximately corresponding to the grain boundaries of the base material portion. Therefore, it is possible to avoid the first layer having an excessive number of grain boundaries. Therefore, the thermal diffusion of the copper in the base material portion along the grain boundaries of the first layer is suppressed. Therefore, the first layer can effectively prevent the thermal diffusion of the copper in the base material portion toward the surface of the plating portion. Therefore, it is possible to prevent a decrease in the connection reliability of the plating portion to other elements due to the thermal diffusion of the copper in the base material portion onto the surface of the plating portion. Second, the second layer of the plating portion has a plurality of randomly formed crystal grains on each of the plurality of crystal grains of the first layer. As a result, the fourth layer of the plating portion, which is separated from the base material portion by the second layer, is formed without being affected by the unevenness of each crystal orientation in the crystal grains forming the surface of the base material portion. Therefore, uneven growth of the fourth layer reflecting the unevenness of each crystal orientation in the crystal grains forming the surface of the base material portion is prevented. Therefore, uneven gloss of the fourth layer can be suppressed. From the above, while suppressing the uneven gloss of the fourth layer, it is possible to maintain the high connection reliability of the plating portion due to the fourth layer containing a noble metal.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a cross-sectional view schematically showing the configuration of an electronic device in Embodiment 1. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the configuration of a package used in the manufacture of the electronic device of FIG. 1. [Figure 3] FIG. 3 is a partially enlarged view showing the dashed-line region III of FIG. 2. [Figure 4] FIG. 4 is a partially enlarged view showing the dashed-line region IV of FIG. 3. [Figure 5] FIG. 5 is a partial cross-sectional view schematically showing an example of the crystal state of the configuration shown in FIG. 4. [Figure 6] FIG. 6 is a cross-sectional view schematically showing one step of the manufacturing method of the package of FIG. 2. [Figure 7]Figure 7 is a schematic partial cross-sectional view showing the light reflection on the mounting surface of the package of the first comparative example. [Figure 8] Figure 8 is a schematic partial cross-sectional view showing the light reflection on the mounting surface of the package of the second comparative example. [Figure 9] Figure 9 is a schematic partial cross-sectional view showing the light reflection on the mounting surface of the package of the third comparative example. [Figure 10] Figure 10 is a schematic partial cross-sectional view showing the light reflection on the mounting surface of the package shown in Figure 5. [Figure 11] Figure 11 is a schematic cross-sectional view showing the configuration of the package in Embodiment 2. [Figure 12] Figure 12 is a schematic cross-sectional view showing the first step of the manufacturing method for the package shown in Figure 11. [Figure 13] Figure 13 is a schematic cross-sectional view showing the second step of the manufacturing method for the package shown in Figure 11. [Figure 14] Figure 14 is a schematic cross-sectional view showing the third step of the manufacturing method for the package shown in Figure 11. [Figure 15] Figure 15 is a schematic cross-sectional view showing the fourth step of the manufacturing method for the package shown in Figure 11. [Figure 16] Figure 16 is a schematic cross-sectional view showing the fifth step of the manufacturing method for the package shown in Figure 11. [Figure 17] Figure 17 is a schematic cross-sectional view showing the sixth step of the manufacturing method for the package shown in Figure 11. [Figure 18] Figure 18 is a schematic cross-sectional view showing the configuration of the package in Embodiment 3. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings. In this specification, unless otherwise specified, "metal" can mean either a pure metal or an alloy. "Alloy" can mean any of a solid solution consisting of multiple metal components, a mixture of multiple metals that are not in solid solution, or an intermetallic compound. The term "green" refers to the state before firing. Therefore, a component labeled "green" will be fired, but has not yet been fired. The terms "up" and "down" are used merely to distinguish relative directions and do not imply any limitation related to the direction of gravity.

[0024] <Embodiment 1> Figure 1 is a schematic cross-sectional view showing the configuration of the electronic device 500 in this embodiment 1. Figure 2 is a schematic cross-sectional view showing the configuration of the package 100 as a component used in the manufacture of this electronic device 500. The electronic device 500 includes the package 100, an electronic component 501, a bonding wire 502, a lid 512, and an adhesive layer 511.

[0025] Package 100 has a mounting surface RM within its cavity CV for mounting an electronic component 501. The electronic component 501 is mounted on the mounting surface RM. The electronic component 501 and the mounting surface RM may be joined to each other by a mounting material layer 508 having sufficient conductivity. The mounting material layer 508 may be formed by sintering an Ag conductive paste, in which case it is a layer containing Ag. The Ag conductive paste may contain a solvent and nano-sized Ag powder dispersed therein. Alternatively, the mounting material layer 508 may be formed by curing an epoxy resin in which Ag powder is dispersed. Alternatively, the mounting material layer 508 may be formed by soldering. This mounting process is typically carried out using a mounting temperature of about 300°C.

[0026] Bonding wires 502 connect the electronic component 501 to the lead frame 50 (external connection terminals) of the package 100. The lid 512 seals the cavity CV of the package 100 by being attached to the package 100. Specifically, the lid 512 and the package 100 are joined to each other by an adhesive layer 511. The adhesive layer 511 consists of, for example, an adhesive containing a resin. The adhesive may be, for example, a thermosetting resin. The adhesive layer 511 is provided on the frame 30 of the package 100 so as to surround the cavity CV. The adhesive layer 511 may have a portion provided on the frame 30 via the lead frame 50. The thickness of the adhesive layer 511 between the lid 512 and the package 100 (vertical dimension in Figure 1) is, for example, 100 μm or more and 360 μm or less. The electronic component 501 may need to be kept in an environment with high airtightness, and may be a semiconductor element, and in particular may be a power semiconductor element. The power semiconductor element may be a high-frequency semiconductor element. A high-frequency semiconductor element is a semiconductor element that operates at frequencies of approximately several tens of MHz (e.g., 30 MHz) to 30 GHz. In this case, the electronic device 500 is a high-frequency module. Power semiconductor elements suitable for high-frequency applications are typically LDMOS (Lateral Diffused MOS) transistors or GaN (Gallium Nitride) transistors.

[0027] The package 100 has a heat dissipation member 170 for effectively removing heat generated from the electronic component 501. The heat dissipation member 170 includes a metal member 70. The metal member 70 may be the heat dissipation member 170, and this case will be described below. The metal member 70 (i.e., the heat dissipation member 170) has a base material portion 10 and plated portions 20H1 and 20H2 formed on the base material portion 10. The package 100 further has a frame 30 provided on the metal member 70 (i.e., the heat dissipation member 170), a lead frame 50, and a plated portion 20L formed on the lead frame 50.

[0028] The base material 10 has a surface SM (upper surface in Figure 2) and a surface SN (lower surface opposite to the upper surface in Figure 2). The frame 30 is arranged to surround at least a portion of surface SM. In this embodiment 1, the frame 30 is arranged on the base material 10 in the thickness direction (vertical direction in Figure 2). The frame 30 may be attached to the base material 10 by a bonding layer 40. The lead frame 50 is fixed to the frame 30. The lead frame 50 may be attached to the frame 30 by a further bonding layer 40.

[0029] The base material 10 is a single sheet or laminate made of metal. At least the portion of the base material 10 that forms the surface SM contains Cu, and the entire base material 10 may contain Cu. The Cu content may be 90 volume% or more. By containing Cu in the base material 10, the thermal conductivity of the base material 10 can be increased. The base material 10 has a plurality of crystal grains that reach the surface SM.

[0030] The plated portion 20H1 is provided on the surface SM of the base material 10. The plated portion 20H1 does not need to be provided over the entire surface SM. For example, as shown in Figure 2, the plated portion 20H1 does not need to be provided on the portion of the surface SM that supports the frame 30. The plated portion 20H2 is provided on at least a portion of the surface SN of the base material 10, and in Figure 2, it is provided over the entire surface SN. Also, as shown in Figure 2, the plated portion 20H2 may extend onto the side surface of the base material 10. The plated portion 20L is provided on at least a portion of the surface of the lead frame 50. The plated portion 20L does not need to be provided on the portion of the surface that is supported by the frame 30. Each of the plated portions 20H1, 20H2, and 20L may be formed by a common multilayer plating process, in which case they have substantially similar configurations. Details of this multilayer plating will be described later.

[0031] Figure 3 is a partially enlarged view showing the dashed area III in Figure 2. The frame 30 may have an insulating frame 31, a metallized film 32, and a plating film 33. The insulating frame 31 is made of ceramics. The metallized film 32 is formed on the upper and lower surfaces of the insulating frame 31. The plating film 33 is formed on the metallized film 32. One metallized film 32 is joined to the base material 10 by a bonding layer 40, and the other metallized film 32 is joined to the lead frame 50 by a bonding layer 40. The bonding layer 40 is, for example, a brazing material. In addition, a frame made of resin may be used instead of the frame 30 having an insulating frame 31, a metallized film 32, and a plating film 33. In that case, the bonding layer 40 is preferably an adhesive layer. The resin frame 30 and the lead frame 50 may be integrally molded, in which case the bonding layer 40 between the frame 30 and the lead frame 50 is omitted.

[0032] Figure 4 is a partially enlarged view showing the dashed region IV in Figure 3. Figure 5 is a schematic partial cross-sectional view illustrating an example of the crystalline state of the configuration shown in Figure 4. In Figure 5, for the base material 10 and layer 21, the edges of the crystal grains are shown with thick lines, and their crystal orientation is schematically represented with thin lines. On the other hand, for layers 22 to 24, the illustration of the crystal grains is omitted. This is because, in this embodiment, the crystal grain size in the in-plane direction (lateral direction in Figure 5) is typically considerably finer in layers 22 to 24 compared to the base material 10 and layer 21, making it difficult to illustrate.

[0033] As described above, a plated portion 20H1 is formed on the surface SM of the base material portion 10. This constitutes a layered plated metal member 70 having a mounting surface RM. The plated portion 20H1 has, in order, layers 21 (first layer), 22 (second layer), 23 (third layer), and 24 (fourth layer in this embodiment 1) on the base material portion 10, which is the member to be plated. The plated portion 20H1 contains Cu at a Cu atom concentration lower than that of the base material portion 10, or it contains substantially no Cu. The Cu contained in the plated portion 20H1 may be substantially due to thermal diffusion from the base material portion 10, in which case the Cu content of the plated portion 20H1 is usually sufficiently small compared to the content of the main component. The Cu content is, for example, 1% by weight or less, more preferably 0.5% by weight or less, even more preferably 0.2% by weight or less, and most preferably 0%. The copper content can be measured by energy-dispersive X-ray spectroscopy (EDX).

[0034] Here, an example of a method for measuring the average crystal grain size in the in-plane direction of the plated portion 20H1 and the substrate portion 10 will be described. In the following, the average crystal grain size in the in-plane direction may be simply referred to as the average crystal grain size. First, a cross section parallel to the thickness direction is formed by processing the metal member 70. An image of this cross section is captured by electron backscatter diffraction (EBSD) mounted on a scanning electron microscope (SEM).

[0035] The average grain size of layers 22, 23, and 24 of the plated portion 20H1 may be calculated by a simple sectioning method using the above image. Specifically, a line segment of known length is drawn on the above image, completely crossing 10 to 50 crystal grains along the in-plane direction. The average grain size is calculated by dividing this known length by the number of these crystal grains.

[0036] On the other hand, with respect to layer 21, it is often difficult to draw the line segments described above so as to cross a sufficient number of crystal grains. This is because the crystal grains of layer 21 have a shape that is relatively large in the in-plane direction and relatively small in the thickness direction, and such a shape extends along the surface SM of the substrate portion 10, which is not necessarily strictly flat at a microscopic level, in a fine undulating manner. Therefore, for layer 21, first, in the above image, 10 crystal grains that are in contact with the substrate portion 10 are randomly selected from among the multiple crystal grains of layer 21. The edges of each of these 10 crystal grains have a curve that forms a boundary with the substrate portion 10. For a given crystal grain, the straight-line distance between the two ends of this curve is considered to be the grain size of that crystal grain. The average of the 10 grain sizes obtained in this way is considered to be the average crystal grain size.

[0037] Similarly, with respect to the base material 10, first, in the image above, 10 crystal grains in contact with the layer 21 are randomly selected from among the multiple crystal grains of the base material 10. The edges of each of these 10 crystal grains have a curve that forms a boundary with the layer 21. For a given crystal grain, the straight-line distance between the two ends of this curve is considered to be the grain size of that crystal grain. The average of the 10 grain sizes obtained in this way is considered to be the average crystal grain size. The average crystal grain size of the base material 10 is, for example, between 10 μm and 1 mm. This is about the same size as the protrusions or foreign matter.

[0038] Layer 21 is provided on the surface SM of the base material 10. The surface SM may be an unpolished surface. In other words, the surface SM may be the surface of the base material 10 immediately after formation (as-grown surface), such as a cast surface or a fired surface. Because polishing is not performed, no bailby layer is formed on the surface SM of the base material 10. Layer 21 has a plurality of crystal grains that are substantially epitaxially formed on a plurality of crystal grains of the base material 10. In other words, layer 21 is substantially an epitaxial layer on the base material 10. To facilitate the formation of the epitaxial layer layer 21, it is preferable that layer 21 be formed directly on the base material 10. In the example shown in Figure 5, the crystal grains D1 to D5 of layer 21 are substantially epitaxially formed on each of the crystal grains C1 to C5 that make up the surface SM of the base material 10. The crystal orientation of each of the crystal grains C1 to C5 may be substantially the same as the crystal orientation of the crystal grains D1 to D5. The crystal orientation may be observed by electron backscatter diffraction (EBSD). Layer 21 may contain Ni. The thickness of layer 21 may be between 0.1 μm and 1.0 μm. The average grain size of layer 21 may be substantially the same as or smaller than the average grain size of the substrate 10. For example, the average grain size of layer 21 may be between 10 μm and 1 mm.

[0039] Layer 22 is provided on layer 21. Layer 22 has a polycrystalline or amorphous structure. In the example shown in Figure 5, layer 22 is formed directly on the crystal grains D1 to D5 of layer 21, but it does not have to be formed directly. Layer 22 is substantially non-oriented with respect to the crystal orientation of the crystal grains D1 to D5 of layer 21. This means that the information about the crystal orientation of the surface SM of layer 21 is substantially lost on the surface of layer 22 (top surface in the figure). As a result, layer 23 grows without being substantially affected by the crystal orientation of the crystal grains of the substrate 10. Layer 22 contains Ni. Layer 22 is, for example, a Ni plating layer having substantially only Ni. Layer 22 has multiple crystal grains formed non-orientedly on each of the multiple crystal grains of layer 21. Therefore, the average crystal grain size of layer 22 is smaller than the average crystal grain size of layer 21. In this embodiment, the thickness of layer 22 may be between 0.3 μm and 6.0 μm. The average grain size of layer 22 may be smaller than the average grain size of layer 23. The average grain size of layer 22 may be smaller than the average grain size of layer 24. Specifically, the average grain size of layer 22 is preferably between 0.05 μm and 3.0 μm, and more preferably between 0.1 μm and 1 μm.

[0040] Layer 23 is provided on layer 22. In the example shown in Figure 5, layer 23 is formed directly on layer 22, but it does not have to be formed directly. Layer 23 has a polycrystalline or amorphous structure. Furthermore, layer 23 is substantially non-oriented with respect to the crystal orientation of grains D1 to D5 of layer 21. As a result, layer 24 grows without being substantially affected by the crystal orientation of the grains of layer 23, and uneven gloss of layer 24 is prevented. Distinction between layer 22 and layer 23 is possible, for example, by differences in average grain size, crystal orientation observation, or composition observation. Layer 23 may contain Ni, and may also contain Co (cobalt). The composition of layer 23 may differ from the compositions of layers 22 and 24. For example, layer 22 is made of Ni, and layer 23 is made of a Ni alloy. This Ni alloy may contain the element Co, for example, a Ni-Co alloy. The average grain size of layer 23 may be larger than the average grain size of layer 22. The thickness of layer 23 may be between 0.5 μm and 6.0 μm. The combined thickness of layers 22 and 23 may be between 0.8 μm and 7 μm. The average grain size of layer 23 is smaller than the average grain size of layer 21. Specifically, the average grain size of layer 23 is preferably between 0.05 μm and 3.0 μm, and more preferably between 0.1 μm and 1 μm.

[0041] Layer 24 is provided on layer 23. In the example shown in Figure 5, layer 24 is formed directly on layer 23, but it does not have to be formed directly. Layer 24 has a mounting surface RM on which the electronic component 501 (Figure 1) will be mounted. Layer 24 contains a precious metal. Preferably, layer 24 contains an Au (gold) layer. In that case, layer 24 may consist only of the Au layer. Alternatively, layer 24 may be a laminate containing an Au layer. This laminate includes a layer made of a precious metal other than Au, such as a Pd (palladium) layer, between the Au layer and layer 23. For example, layer 24 is a laminate composed only of an Au layer and a Pd layer. The Pd layer has the function of blocking the diffusion of Ni atoms into the Au layer. This prevents discoloration of the Au layer due to the diffusion of Ni into the Au layer during the heating process. If layer 24 is an Au layer, its thickness may be between 0.5 μm and 3.0 μm. If layer 24 is a laminate of an Au layer and a Pd layer, the thickness of the Au layer may be about 0.1 μm, and the thickness of the Pd layer may be between 0.05 μm and 0.4 μm. The average grain size of layer 24 is smaller than the average grain size of layer 21. The average grain size of layer 24 may be substantially the same as or smaller than the average grain size of layer 23. Specifically, the average grain size of layer 24 is preferably between 0.05 μm and 3.0 μm, and more preferably between 0.1 μm and 1 μm.

[0042] The surface roughness of the surface of layer 22 (top surface in the figure) is preferably somewhat rough. The surface roughness has a maximum height Ry of, for example, 0.3 μm or more. This makes it easier to suppress the grain size of layer 23. Also, as a result of selecting plating conditions that make layer 22 non-oriented, the surface roughness of layer 22 tends to be large. If we assume that layer 24 as a noble metal plating layer is formed directly on such a rough surface, a large thickness is required to obtain a uniform noble metal plating layer. Since noble metals, especially Au, are expensive, this leads to an increase in material costs. Therefore, in this embodiment, layer 24 is formed on layer 22 via layer 23, which does not need to contain noble metal. The surface roughness of layer 23 is preferably smaller than the surface roughness of layer 22. The maximum height Ry is measured by taking a reference length from the roughness curve in the direction of its average line and measuring the distance between the peak and trough lines of this sampled portion in the direction of the vertical magnification of the roughness curve. The reference length may be a field of view of the same extent as shown in Figure 5.

[0043] Figure 6 is a schematic cross-sectional view showing one step in the manufacturing process of package 100 (Figure 2). First, a base material 10, a frame 30, and a lead frame 50 are prepared. The base material 10 can be formed, for example, by casting and / or a combination thereof. The surface SM of the base material 10 thus formed does not need to be polished. In other words, a base material 10 having a surface SM made up of multiple crystal grains may be prepared without polishing the surface SM. Next, these components are joined to each other by a bonding layer 40. This results in the illustrated configuration.

[0044] Next, a plating process is performed to form layers 21 to 24 of the plated sections 20H1, 20H2, and 20L (Figure 2) in this order. First, layer 21 is formed epitaxially on the substrate section 10. By setting the plating speed sufficiently low, layer 21 can be formed epitaxially on the substrate section 10. Next, layer 22 is formed unorientedly on layer 21. As a constraint on the plating conditions for layer 22, the plating conditions are selected so that layer 22 is unoriented with respect to the crystal orientation of layer 21. If layer 22 has a polycrystalline structure, its grain size can also be adjusted by the plating conditions. These conditions include, for example, the pH of the plating solution, the Ni concentration of the plating solution, the current density, the crystal firing agent, and the temperature. Next, layer 23 is formed on layer 22. The plating conditions for layer 23 can be selected without the above constraints imposed on the plating conditions for layer 22. Next, layer 24 is formed sequentially on layer 23. This results in package 100 (Figure 2).

[0045] Figure 7 is a schematic partial cross-sectional view showing the light reflection on the mounting surface RM of package 100A of the first comparative example. The plated portion 20A of package 100A is composed of a base layer 23A and a precious metal plating layer 24A. The process conditions for forming the base layer 23A and the precious metal plating layer 24A are the same as the process conditions for forming layers 23 and 24. Unlike layer 23 (Figure 5), the base layer 23A is not separated from the surface SM by the non-oriented layer 22 (Figure 5). Therefore, the base layer 23A grows under the influence of the unevenness of the crystal grains C1 to C5 that make up the surface SM of the substrate portion 10. Specifically, the base layer 23A grows under the influence of the unevenness of each crystal orientation in the crystal grains C1 to C5 that make up the surface SM of the substrate portion 10. Therefore, the precious metal plating layer 24A formed on the base layer 23A also grows under the influence of the unevenness of the crystal grains C1 to C5. Specifically, the noble metal plating layer 24A formed on the underlayer 23A also grows under the influence of unevenness in the crystal orientation of each crystal grain C1 to C5. As a result, the mounting surface RM has areas where relatively small crystal grains are clustered and areas occupied by large crystal grains. The reflected light of incident light LTa to the former areas is relatively easily diffused. On the other hand, the reflected light of incident light LTb to the latter areas tends to be relatively strong. As a result, the unevenness of the gloss of the noble metal plating layer 24A becomes larger.

[0046] Figure 8 is a schematic partial cross-sectional view showing the light reflection on the mounting surface RM of package 100B of the second comparative example. As with Figure 5, the grain boundaries of the substrate portion 10 are depicted, while the grain boundaries of the plated portion 20B are omitted from the illustration.

[0047] The plated portion 20B of package 100B is formed after the bail ruby ​​layer 19 is formed on the surface SM of the substrate portion 10. The plated portion 20B consists of an underlayer 23B and a precious metal plating layer 24B. The process conditions for forming the underlayer 23B and the precious metal plating layer 24B are the same as the process conditions for forming layers 23 and 24. The bail ruby ​​layer 19 is formed by polishing the surface SM. Since the underlayer 23B is separated from the surface SM by the bail ruby ​​layer 19, it grows without being affected by the unevenness of the crystal grains C1 to C5 that make up the surface SM of the substrate portion 10. Specifically, the underlayer 23B grows without being affected by the unevenness of each crystal orientation in the crystal grains C1 to C5 that make up the surface SM of the substrate portion 10. Therefore, the precious metal plating layer 24B formed on the underlayer 23B also grows without being affected by the unevenness of the crystal grains C1 to C5. Specifically, the precious metal plating layer 24B formed on the underlayer 23B grows without being affected by the unevenness of the crystal orientations in the crystal grains C1 to C5. As a result, the dispersion state of the reflected light of the incident light LT tends to be uniform. Therefore, the unevenness of the luster of the precious metal plating layer 24B can be reduced compared to the precious metal plating layer 24A of package 100A (Figure 7). However, this comparative example requires a polishing process to form the bail bee layer 19. The polishing process is a significant burden in manufacturing.

[0048] Furthermore, in this comparative example, layer 21 is not interposed between the Cu-containing substrate portion 10 and layer 24 as a noble metal layer. Since layer 21 is epitaxially formed on the substrate portion 10, it has fewer grain boundaries than layers 22 to 24. Since thermal diffusion of Cu tends to occur along grain boundaries, layer 21, which has fewer grain boundaries, functions as a barrier layer to prevent thermal diffusion. Because this comparative example lacks such a barrier layer, thermal diffusion of Cu from the substrate portion 10 toward the surface of the plated portion 20C (arrow MC in the figure) is likely to occur. This surface of the plated portion 20C forms the mounting surface RM of the package 100C. Therefore, it is possible that the connection reliability of the mounting surface RM to the mounting material layer 508 (Figure 1) for the electronic component 501 may decrease due to the diffusion of Cu onto the mounting surface RM.

[0049] Figure 9 is a schematic partial cross-sectional view showing the light reflection on the mounting surface RM of package 100C of the third comparative example. The plated portion 20C of package 100C corresponds to the plated portion 20H1 (Figure 5) with layer 21 omitted. In this comparative example, layer 21 is not interposed between the Cu-containing substrate portion 10 and the noble metal layer 24. Since layer 21 is formed epitaxially on the substrate portion 10, it has fewer grain boundaries than layers 22 to 24. Since thermal diffusion of Cu tends to occur along grain boundaries, layer 21, which has fewer grain boundaries, functions as a barrier layer to prevent thermal diffusion. Because this comparative example lacks such a barrier layer, thermal diffusion of Cu from the substrate portion 10 toward the surface of the plated portion 20C (arrow MC in the figure) is likely to occur. This surface of the plated portion 20C forms the mounting surface RM of package 100C. Therefore, it is possible that the diffusion of Cu onto the mounting surface RM may reduce the reliability of the connection between the mounting surface RM and the mounting material layer 508 (Figure 1) for the electronic component 501.

[0050] According to this embodiment 1, firstly, the layer 21 (Figure 5) of the plated portion 20H1 is epitaxially formed on the surface SM of the base material portion 10. As a result, the grain boundaries of the layer 21 are formed to roughly correspond to the grain boundaries of the base material portion 10. Therefore, it is avoided that the layer 21 has an excessive number of grain boundaries. Therefore, thermal diffusion of Cu from the base material portion 10 along the grain boundaries of the layer 21 is suppressed. Thus, the layer 21 can effectively prevent thermal diffusion of Cu from the base material portion 10 toward the surface of the plated portion 20H1. This surface of the plated portion 20H1 forms the mounting surface RM of the package 100. Therefore, it is possible to prevent a decrease in the reliability of the connection of the mounting surface RM to the mounting material layer 508 (Figure 1) for the electronic component 501 due to thermal diffusion of Cu from the base material portion 10 toward the mounting surface RM. Secondly, layer 22 of the plated portion 20H1 has multiple crystal grains (not shown in Figure 10) formed unorientedly on each of the multiple crystal grains D1 to D5 (Figure 10) of layer 21. As a result, layer 24 of the plated portion 20H1, separated from the base material portion 10 by layer 22, is formed without being affected by the unevenness of the crystal orientation of the crystal grains C1 to C5 that make up the surface of the base material portion 10. Therefore, uneven growth of layer 24 that reflects the unevenness of the crystal orientation of the crystal grains C1 to C5 that make up the surface SM of the base material portion 10 is prevented. Thus, the gloss unevenness of layer 24 can be suppressed in the same way as in the second comparative example (Figure 8) described above. From the above, it is possible to suppress the gloss unevenness of layer 24 while maintaining the high connection reliability of the plated portion 20H1 due to the inclusion of a precious metal in layer 24.

[0051] Layer 22 has multiple crystal grains formed unorientedly on each of the multiple crystal grains D1 to D5 (Figure 10) of layer 21. Therefore, the average crystal grain size of layer 22 is smaller than the average crystal grain size of layer 21. As a result, layer 23 can grow with less influence from the crystal orientation of the crystal grains of the substrate 10.

[0052] As explained with reference to the comparative example package 100A (Figure 7), gloss unevenness is originally caused by unevenness in the size of the crystal grains C1 to C5 that make up the surface SM of the substrate portion 10. Therefore, this gloss unevenness tends to be a problem when the average crystal grain size of the substrate portion 10 is relatively large, and is particularly problematic when it is about 10 μm or larger. In that case, the average crystal grain size of layer 21, which is a layer substantially epitaxially formed on the substrate portion 10, also tends to be about 10 μm or larger. In such cases, according to this embodiment 1, gloss unevenness can be effectively suppressed as described above. Note that the average crystal grain size of the substrate portion 10 is usually at most about 1 mm or less, and correspondingly the average crystal grain size of layer 21 may also be 1 mm or less.

[0053] Protrusions or foreign objects on the mounting surface RM can adversely affect the connection reliability of the electronic component 501 (Figure 1). Therefore, it is desirable to perform an inspection to detect protrusions or foreign objects on the mounting surface RM before the mounting process. In mass production, this inspection is preferably performed by an automated visual inspection using a camera. If the mounting surface RM has excessive unevenness in gloss when photographed by the camera, the resulting contrast may be mistaken for a protrusion or foreign object. In particular, precious metal plating layers such as the Au plating layer usually have high gloss if they are flat. Therefore, the contrast due to uneven gloss tends to be large. According to this embodiment, in the inspection of the mounting surface RM, misidentification due to uneven gloss can be prevented for the reasons mentioned above.

[0054] The surface SM of the base material 10 may be an unpolished surface. This eliminates the need for a surface polishing step for the base material 10. Since the polishing step is a labor-intensive process, omitting it simplifies the manufacturing method of the base material 10. Note that if the surface SM of the base material 10 is an unpolished surface, the bailby layer 19 (Figure 8) will not be formed on the surface SM.

[0055] Since layer 22 is required to be unoriented with respect to the crystal grains D1 to D5 of layer 21, it is preferable to select a composition suitable for this. Specifically, since layer 22 is required to be unoriented with respect to each crystal orientation of the crystal grains D1 to D5 of layer 21, it is preferable to select a composition suitable for this. In contrast, since layer 23 is not subject to such constraints, a composition different from that of layer 22 can be selected more freely. For example, layer 22 is made of Ni and layer 23 is made of a Ni alloy. The Ni alloy may contain the element Co.

[0056] Layer 21 may contain Ni. In that case, layer 21 and the base material 10, which is a Cu-containing material, are likely to bond strongly to each other. Also, layer 21 and layer 22, which is a Ni-containing layer, are likely to bond strongly to each other.

[0057] Layer 23 may contain Ni. In that case, layer 23 and layer 22, which contains Ni, tend to bond strongly to each other. Also, layer 23 and layer 24, which contains a precious metal, tend to bond strongly to each other.

[0058] Layer 23 may contain Co. In that case, when the electronic component 501 (Figure 1) is mounted on the mounting surface RM of layer 24, the phenomenon of voids contained in layer 23 moving to the mounting surface RM of layer 24 can be suppressed. In other words, the inclusion of Co has the effect of fixing voids. This can improve the mounting reliability of the electronic component 501.

[0059] The average grain size of layer 24 is preferably 3.0 μm or less, and more preferably 1 μm or less. This allows for more effective suppression of gloss unevenness in layer 24. In order to make the average grain size of layer 24 preferably 3.0 μm or less, and more preferably 1 μm or less, it is preferable to make the average grain size of layer 23 preferably 3.0 μm or less, and more preferably 1 μm or less. In order to make the average grain size of layer 23 preferably 3.0 μm or less, and more preferably 1 μm or less, it is preferable to make the average grain size of layer 22 preferably 3.0 μm or less, and more preferably 1 μm or less. The lower limit of the average grain size of layers 22 to 24 is not particularly limited, but if the grain size is 0.1 μm or more, electroplating is easier to apply.

[0060] The combined thickness of layers 22 and 23 may be between 0.8 μm and 7 μm. A combined thickness of 0.8 μm or more makes it easier to ensure sufficient effects from layers 22 and 23. A combined thickness of 7 μm or less avoids excessive thermal resistance caused by layers 22 and 23.

[0061] Layer 24 may be an Au layer. This enhances the effect of preventing corrosion of the base material 10 by layer 24.

[0062] <Modified form of Embodiment 1> If the effect of layer 23 is unnecessary, layer 23 may be omitted from the plated portion 20H1. In this case, the plated portion includes layer 21 (first layer), layer 22 (second layer) provided on layer 21, and layer 24 (fourth layer) directly provided on layer 22. In this modified example, the thickness of layer 22 may be 0.8 μm or more and 7.0 μm or less. As in the first embodiment, in this modified example, layer 24 may be composed of, for example, a single layer of Au, or a laminate of Au and Pd layers.

[0063] According to this modified example, the layer structure of the plated portion can be further simplified while obtaining effects similar to those of the first embodiment described above.

[0064] <Embodiment 2> Figure 11 is a schematic cross-sectional view showing the configuration of package 111 in this second embodiment. Package 111 may be used in place of package 100 (Figure 2: Embodiment 1) in the manufacture of electronic device 500 (Figure 1).

[0065] Package 111 has a heat dissipation member 171 for effectively removing heat generated from the electronic component 501 (see Figure 1). The heat dissipation member 171 has a metal member 71 and a support member 81 that supports the metal member 71. The metal member 71 has a base material portion 10 and a plated portion 20H1 formed on the base material portion 10. Package 111 also has a frame 30F provided on the heat dissipation member 171. The frame 30F is positioned on the support member 81 in the thickness direction (vertical direction in Figure 11). The frame 30F does not need to be positioned on the base material portion 10 of the metal member 71 in the thickness direction (vertical direction in Figure 11). In other words, the frame 30F may be positioned away from the base material portion 10 of the metal member 71 in a planar layout perpendicular to the thickness direction.

[0066] The base material 10 has a surface SM facing the cavity CV, a bottom surface SB opposite to the surface SM, and a side surface SC3 connecting the surface SM and the bottom surface SB. The surface SM may be a substantially flat surface. The bottom surface SB may be a substantially flat surface. The side surface SC3 may be a substantially flat surface. The plated portion 20H1 is formed on the surface SM. The plated portion 20H1 has a surface facing the surface SM and a mounting surface RM opposite to that surface.

[0067] The base material 10 preferably contains 90% by volume of Cu. When the base material 10 contains 90% by volume of Cu as the main component, the remaining components may be any, and may be metal, ceramic, or both. The base material 10 may be, for example, a Cu plate or a Cu alloy plate. The thermal conductivity of the base material 10 is greater than that of the support member 81. Such a high thermal conductivity can be easily obtained by increasing the Cu content.

[0068] The frame 30F is attached to the support member 81 and surrounds the cavity CV. In this second embodiment, the frame 30F is made of ceramic. This ceramic may have alumina as its main component. Other oxides may be added to this alumina, for example, silicon oxide, manganese oxide, or both. The coefficient of linear expansion of the frame 30F is smaller than the coefficient of linear expansion of the base material 10. Considering that the mounting process of the electronic component 501 (see Figure 1) is typically carried out using a mounting temperature of about 300°C, the coefficient of linear expansion in this specification may be the average coefficient of linear expansion between 25°C (room temperature) and 300°C (mounting temperature).

[0069] The support member 81 has an upper surface SW1 and a lower surface SW2 opposite to the upper surface SW1. The upper surface SW1 includes a support surface SW1a facing the bottom surface SB of the base material 10 and a surface SW1b facing the bottom surface of the frame 30F. In an in-plane layout perpendicular to the thickness direction (vertical direction in Figure 11), i.e., a planar layout, the support surface SW1a is surrounded by surface SW1b. The support surface SW1a may be a substantially flat surface. Surface SW1b may be a substantially flat surface. In this embodiment, a recess is formed in the upper surface SW1 of the support member 81, and the surface lowered by this recess than surface SW1b is the support surface SW1a. As a result, the support member 81 has an inner wall surface SW3 connecting the support surface SW1a and surface SW1b. The inner wall surface SW3 faces the side surface SC3 of the base material 10. In this embodiment 2, the surface SM of the base material 10 and the surface SW1b of the support member 81 are at approximately the same height, but the surface SW1b may be at a higher or lower position than the surface SM.

[0070] The support member 81 may contain metal. Specifically, the support member 81 may contain 10% to 60% by volume of Cu, W, Mo, or both W and Mo as the metal. These volume percentages are determined by the weight percentage measurements obtained by elemental analysis and the density values ​​of each element (Cu: 8.96, W: 19.3, Mo: 10.28 (unit: g / cm³)). 3It can be calculated by )). As a modified example, the support member 81 may contain both metal and ceramic, for example, 10% to 60% by volume of Cu, W, Mo, or both W and Mo, and ceramic. The coefficient of linear expansion of the support member 81 is smaller than the coefficient of linear expansion of the base material 10. For example, if the support member 81 contains a Cu-W alloy, the coefficient of linear expansion can be reduced by increasing the composition ratio of W to Cu.

[0071] The support member 81 and the frame 30F may be composite parts formed by co-firing, as described later. In this case, the support member 81 and the frame 30F are directly joined to each other by sintering. This composite part includes a base PB included in the support member 81, a first surrounding portion PS1 included in at least one of the support member 81 and the frame 30F, and a second surrounding portion PS2 included in the frame 30F. In the example shown in Figure 11, the first surrounding portion PS1 does not include the frame 30F, but a modified version in which the first surrounding portion PS1 also includes the frame 30F can be obtained by deforming the configuration in Figure 11 so that the interface between the frame 30F and the support member 81 is lower than the surface SM and higher than the bottom surface SB in the thickness direction. The base PB faces the bottom surface SB of the base material 10. The first surrounding portion PS1 faces the side surface SC3 of the base portion 10 so as to surround the base portion 10 on the base portion PB. The second surrounding portion PS2 is located on the first surrounding portion PS1 and surrounds the cavity CV.

[0072] The joining member MJ joins the base material 10 and the support member 81 to each other. The joining member MJ includes a portion MJ1 and a portion MJ2. Part MJ1 is provided between the bottom surface SB and the base PB of the base material 10 and is joined to the bottom surface SB and the base PB of the base material 10, respectively. Part MJ2 is provided between the side surface SC3 of the base material 10 and the first surrounding portion PS1 and is joined to the side surface SC3 of the base material 10 and is in contact with the first surrounding portion PS1. In this embodiment, at least a portion of the first surrounding portion PS1 consists of the support member 81 and is joined to the joining member MJ. In particular, in the example shown in Figure 11, the first surrounding portion PS1 consists of the support member 81 and is joined to the joining member MJ.

[0073] In a cross-sectional view parallel to the thickness direction (Figure 11), it is preferable that the side surface SC3 of the base material 10 and the first surrounding portion PS1 are joined to the joining member MJ. This restrains the side surface SC3 of the base material 10 to the first surrounding portion PS1 via the joining member MJ. This restraint can alleviate the stress generated in the mounting material layer 508 (Figure 1) due to the thermal expansion and contraction of the base material 10. In the same cross-sectional view, it is also possible that the entire side surface SC3 of the base material 10 and the first surrounding portion PS1 are joined to the joining member MJ. In the same cross-sectional view, it is preferable that the space sandwiched between the base material 10 and the first surrounding portion PS1 in the in-plane direction perpendicular to the thickness direction is filled by a portion MJ2 of the joining member MJ. This restrains the side surface SC3 of the base material 10 to the first surrounding portion PS1 via a portion MJ2 of the joining member MJ. This restraint can alleviate the stress generated in the mounting material layer 508 (Figure 1). In the cross-sectional view, the entire space may or may not be filled with the joining member MJ. The joining member MJ does not need to extend onto the surface SM of the base material 10, but it may extend onto the surface SM of the base material 10.

[0074] The joining member MJ may contain an alloy material having a melting point lower than that of the base material 10 and the support member 81. This alloy material may be a brazing material. In other words, the joining member MJ may be a brazing material layer. The brazing material may contain Ag and Cu. Because the joining member MJ is a brazing material layer, the base material 10 can be joined to the support member 81 by brazing in the manufacturing method of the package 111.

[0075] The thermal conductivity of the joining member MJ is preferably greater than that of the support member 81. The thermal conductivity of the joining member MJ is preferably 300 W / m·K or higher. Such a high thermal conductivity can be easily obtained by using a brazing layer made of a brazing material containing Ag and Cu as the joining member MJ. On the other hand, the thermal conductivity of the base material 10 may be greater than that of the joining member MJ.

[0076] It is preferable that the Young's modulus of the joining member MJ is smaller than that of the support member 81. It is preferable that the Young's modulus of the joining member MJ is 150 GPa or less. By having a Young's modulus of the joining member MJ smaller than that of the support member 81, the stress generated in the joining member MJ can be reduced. Such a small Young's modulus can be easily obtained by using a brazing layer made of brazing material containing Ag and Cu as the joining member MJ.

[0077] The package 111 may further include a metallized film 32, a bonding layer 40 which is a brazing material layer, and a lead frame 50. The metallized film 32 is provided on the surface of the frame 30F opposite to the surface facing the support member 81. The lead frame 50 is bonded to the metallized film 32 using the bonding layer 40. A plated portion 20L may be provided on the lead frame 50.

[0078] Furthermore, since the configuration other than those described above is substantially the same as that of package 100 (Figure 2: Embodiment 1) or its modified form, the same reference numerals are used for the same or corresponding elements, and their descriptions are not repeated.

[0079] Figures 12 to 17 are schematic cross-sectional views illustrating the first to sixth steps of the manufacturing method for package 111.

[0080] Referring to Figure 12, a green sheet 30G is formed, which includes a portion that will become the frame 30F (Figure 11) upon firing. Typically, to form a green sheet, a slurry is first prepared. The slurry is obtained by mixing powders that will become components of the sintered body with resin, plasticizers, and solvents using a ball mill. The powders used for the slurry to form the frame 30F include, for example, the main component Al2O3 powder, as well as sintering aids such as silicon oxide powder and manganese oxide powder. Using this slurry, the green sheet 30G can be formed by the doctor blade method. Next, an additional layer 32G is formed on the green sheet 30G, which will become a metallized film 32 upon firing. This formation may be carried out by printing a paste. This paste may contain metal powder containing Cu and at least one high-melting-point metal selected from the group consisting of W and Mo.

[0081] Referring to Figure 13, a green sheet 22G1 is formed by firing, which includes a portion of the support member 81 that is included in the first surrounding portion PS1. The main components of the powder used for the slurry to form the green sheet 22G1 are Cu powder and W powder, etc. Specifically, the process of forming the green sheet 22G1 may be carried out using a metal powder containing Cu and at least one high-melting-point metal selected from the group consisting of W and Mo. This metal powder may be a mixed powder of a Cu-containing powder and a high-melting-point metal-containing powder. The Cu-containing powder may be Cu powder. Ceramic powder may also be included. The slurry is processed into a green sheet by the doctor blade method. Next, this green sheet 22G1 and the configuration described in Figure 12 are laminated together. Next, through holes HL corresponding to the cavity CV and the recess of the support member 81 are formed in this laminate.

[0082] Referring to Figure 14, a green sheet 22G2 is formed by firing, which has a portion that will be included in the base PB of the support member 81. The method of forming it may be the same as the method of forming the green sheet 22G1 described above. Next, this green sheet 22G2 and the configuration described in Figure 13 are laminated together. The resulting laminate includes a green member 22G having the green sheet 22G1 and the green sheet 22G2. The green member 22G is a member that will become the support member 81 by firing. Next, this laminate is fired. The firing temperature is, for example, 1100°C or higher and 1400°C or lower. By firing at a temperature of 1100°C or higher, the laminate can be heated to a temperature higher than the melting point of Cu. This makes it possible to form a high-quality support member 81 containing Cu. On the other hand, by firing at a temperature of 1400°C or lower, it is possible to avoid process difficulties caused by excessively high firing temperatures. For example, it is possible to avoid excessive evaporation of Cu during firing. As a result of the above steps, the fired body shown in Figure 15 is obtained.

[0083] Referring to Figure 16, the lead frame 50 is placed on the metallized film 32 via a brazing sheet 40G. The base material 10 is also placed on the support member 81 via a brazing sheet MJG. The brazing sheet is a sheet used for brazing by heating, and may be a substantially flat sheet. Next, the brazing sheet 40G and the brazing sheet MJG are heated for brazing. This causes the brazing sheet 40G and the brazing sheet MJG to melt, thereby performing brazing. As a result, the brazing sheet 40G becomes the joint layer 40, and the brazing sheet MJG becomes the joint member MJ. At this time, the liquid metal produced by the melting of the brazing sheet MJG creeps up between the side surface SC3 of the base material 10 and the inner wall surface SW3 of the support member 81, as shown by the arrow in Figure 16.

[0084] As a result, the configuration shown in Figure 17 is obtained. A plating process similar to the plating process described in Embodiment 1 above is performed on this configuration. This results in the package 111 (Figure 11).

[0085] In the above manufacturing method, the frame 30F and the support member 81 are formed by simultaneous firing, and thus the frame 30F and the support member 81 are directly joined together. As a variation of the manufacturing method, the frame 30F and the support member 81 may be formed separately and then joined together by brazing. In that case, a metallized film may be provided on the surface of the frame 30F that faces the brazing material. If the support member 81 is made of a material that is difficult to braze, a metallized film may also be provided on the surface of the support member 81 that faces the brazing material.

[0086] This second embodiment also provides substantially the same effects as the first embodiment described above.

[0087] Furthermore, according to this second embodiment, referring to Figure 11, firstly, the thermal conductivity of the base material portion 10 having a surface SM facing the cavity CV is greater than the thermal conductivity of the support member 81. This makes it possible to increase the thermal conductivity of the portion near the surface SM. Thus, the heat dissipation characteristics from the surface SM facing the cavity CV can be improved. Secondly, the linear expansion coefficients of the support member 81 and the frame 30F are smaller than the linear expansion coefficient of the base material portion 10. As a result, the base material portion 10 expands more than the first surrounding portion PS1. Here, the joining member MJ joined to the side surface SC3 of the base material portion 10 is in contact with the first surrounding portion PS1. As a result, when thermal expansion occurs in the package 111, the side surface SC3 of the base material portion 10 is pressed down by the first surrounding portion PS1 via a portion MJ2 of the joining member MJ. Thus, excessive thermal expansion of the portion near the surface SM in the package 111 can be suppressed. From the above, it is possible to improve the heat dissipation characteristics of the package 111 and suppress excessive thermal expansion in the vicinity of the surface SM of the package 111.

[0088] At least a portion of the first surrounding portion PS1 may consist of a support member 81 and be joined to the joining member MJ. This allows the side surface SC3 of the base material 10 to be pulled by the first surrounding portion PS1 via the portion MJ2 of the joining member MJ when cooling shrinkage occurs in the package 111. Therefore, excessive cooling shrinkage in the vicinity of the surface SM of the package 111 can be suppressed. If the first surrounding portion PS1 were merely in contact with the joining member MJ and not joined, cooling would cause the first surrounding portion PS1 and the portion MJ2 of the joining member MJ to separate, and the first surrounding portion PS1 would not be able to pull the side surface SC3 of the base material 10 via the portion MJ2 of the joining member MJ.

[0089] The thermal conductivity of the joining member MJ may be greater than that of the support member 81. This ensures that the thermal conductivity of the joining member MJ in the vicinity of the base material 10 is greater than that of the support member 81. Therefore, the heat dissipation characteristics of the package 111 can be further improved.

[0090] The alloy material of the joining member MJ may be a brazing material containing Ag and Cu. This allows the joining member MJ to be formed by brazing, and the high thermal conductivity of the joining member MJ further improves the heat dissipation characteristics of the package 111.

[0091] The base material 10 may contain 90% or more by volume of Cu. This makes it easy to increase the thermal conductivity of the base material 10. Therefore, the heat dissipation characteristics of the package 111 can be further improved.

[0092] The support member 81 may contain 10% to 60% by volume of Cu, and W, Mo, or both W and Mo. This allows the support member 81 to have a thermal conductivity that is not too low and a coefficient of linear expansion that is not too high.

[0093] <Embodiment 3> Figure 18 is a schematic cross-sectional view showing the configuration of package 112 in Embodiment 3. In package 112, at least a portion of the first surrounding portion PS1 consists of a frame 30F and is in contact with a portion MJ2 of the joining member MJ. In particular, the structure of package 112 illustrated in Figure 18 is obtained by shifting the interface between the frame 30F and the support member 81 in the thickness direction to the support surface SW1a of the upper surface SW1 of the support member 81, compared to the configuration of package 111 (Figure 11: Embodiment 2), and by applying deformation to the upper surface SW1 having the support surfaces SW1a and SW1b to make it a flat surface. In this case, the entire first surrounding portion PS1 consists of the frame 30F.

[0094] Furthermore, since the configurations other than those described above are substantially the same as those of Embodiment 2 or its modified form, the same reference numerals are used for the same or corresponding elements, and their descriptions are not repeated.

[0095] This third embodiment also provides substantially the same effects as the first embodiment described above.

[0096] Furthermore, according to this third embodiment, at least a portion of the first surrounding portion PS1 is made of a frame 30F and is in contact with a portion MJ2 of the joining member MJ. As a result, when thermal expansion occurs in the package 112, at least a portion (all in the example shown in Figure 18) of the first surrounding portion PS1 that presses down on the side surface SC3 of the base material portion 10 via the portion MJ2 of the joining member MJ is made of a ceramic frame 30F instead of a support member 81. Therefore, the effect of pressing down on the base material portion 10 can be further enhanced.

[0097] Furthermore, compared to package 111 (Figure 11: Embodiment 2), the outer surface of package 112 (right or left side in Figure 18) has a larger distance between the lead frame 50 and the support member 81 made of conductive material, i.e., the insulation distance, which is the distance separated by the frame 30F made of insulating material. This suppresses the parasitic capacitance of package 112. Therefore, the transmission characteristics of high-frequency signals passing through the lead frame 50 can be improved.

[0098] Furthermore, compared to package 111 (Figure 11: Embodiment 2), package 112 (Figure 18: Embodiment 2) occupies a smaller volume proportion of the package due to the support member 81, which is made of a material having a larger coefficient of linear expansion than the frame 30F. This suppresses warping of the package caused by differences in expansion and contraction between the support member 81 and the frame 30F. The processes that cause this expansion and contraction are, for example, the simultaneous firing process for forming the support member 81 and the frame 30F at the same time, or the brazing process for joining the support member 81 and the frame 30F together.

[0099] The multiple embodiments and their variations described above may be freely combined with one another. Although the invention has been described in detail, the above description is illustrative in all embodiments and does not limit the invention thereto. It is understood that countless variations not illustrated can be envisioned without falling outside the scope of the invention. [Explanation of Symbols]

[0100] 508: Mounting material layer 10: Base material part 19: Baleby Formation 20H1: Plating part 21~24: 1st~4th layer 30: Frame 50: Lead frame 70,71: Metal components 81: Support member 100,111,112: Package 170,171: Heat dissipation components 500:Electronic equipment 501: Electronic components 502: Bonding wire RM: Implementation side

Claims

1. A base material containing copper, having a surface, and having a plurality of crystal grains reaching the surface, The material comprises a plated portion provided on the surface of the base material, wherein the plated portion contains copper at a copper atom concentration lower than that of the base material, or substantially contains no copper, and the plated portion is A first layer provided on the surface of the substrate portion, having a plurality of crystal grains epitaxially formed on the plurality of crystal grains of the substrate portion, A second layer provided on the first layer, containing nickel, and having a plurality of crystal grains formed unoriented on each of the plurality of crystal grains of the first layer, A third layer is provided on the aforementioned second layer, A fourth layer provided on the third layer and containing a precious metal, Metal components.

2. A base material containing copper, having a surface, and having a plurality of crystal grains reaching the surface, The material comprises a plated portion provided on the surface of the base material, wherein the plated portion contains copper at a copper atom concentration lower than that of the base material, or substantially contains no copper, and the plated portion is A first layer provided on the surface of the substrate portion, having a plurality of crystal grains epitaxially formed on the plurality of crystal grains of the substrate portion, A second layer provided on the first layer, containing nickel, and having a plurality of crystal grains formed unoriented on each of the plurality of crystal grains of the first layer, A fourth layer, which is provided directly on the second layer and contains a precious metal, Metal components.

3. A metal member according to claim 1, wherein the third layer of the plated portion contains nickel.

4. A metal member according to claim 3, wherein the third layer of the plated portion contains cobalt.

5. A metal member according to any one of claims 1 to 4, wherein the surface of the base material is an unpolished surface.

6. A metal member according to any one of claims 1 to 4, wherein no bailby layer is formed on the surface of the base material.

7. A metal member according to any one of claims 1, 3, and 4, wherein the third layer of the plated portion has an average grain size that is larger than the average grain size of the second layer.

8. A metal member according to any one of claims 1 to 4, wherein the first layer of the plated portion contains nickel.

9. A heat dissipation member comprising a metal member according to any one of claims 1 to 4, wherein the fourth layer of the plated portion of the metal member has a mounting surface on which electronic components will be mounted.

10. The heat dissipation member according to claim 9, A frame provided on the heat dissipation member, A package that includes the following features.

11. A package according to claim 10, wherein the frame is arranged on the base material in the thickness direction.

12. A package according to claim 10, wherein the heat dissipation member further comprises a support member for supporting the metal member, and the frame is disposed on the support member in the thickness direction.

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