Package, electronic device, and package manufacturing method

Abstract

A frame body (21) has a first surface (SF1) attached to a heat dissipation plate (22) and a second surface (SF2) opposite thereto, and is made of a ceramic sintered body. The second surface (SF2) includes an inner region (R1), an intermediate region (R2), and an outer region (R3). A metallized layer (31) has an inner portion (P1), an intermediate portion (P2), and an outer portion (P3) that are respectively located on the inner region (R1), the intermediate region (R2), and the outer region (R3). A lead frame (30) is mounted on the outer portion (P3). A coating layer (40) covers the intermediate portion (P2), and is made of a ceramic material. The lead frame (30), the inner region (R1), and the outer region (R3) are gold-plated, and the surface of the coating layer (40) is not gold-plated.

Description

Package, electronic device, and method for manufacturing the package

[0001] The present invention relates to a package, an electronic device, and a method for manufacturing the package, and more particularly to a package having a cavity, an electronic device having the package, and a method for manufacturing the package.

[0002] International Publication No. 2018 / 225511 (Patent Document 1) discloses a lid for a package. The lid is attached to an electronic component storage package having a cavity. The cavity is sealed by attaching the lid. The lid has a base portion and a sealing portion. The sealing portion is provided on the base portion and is made of a resin adhesive primarily composed of a thermosetting resin. The sealing portion includes a base layer disposed on the base portion in a cured state and an adhesive layer disposed on the base layer in a semi-cured state. This lid includes the base layer and the adhesive layer. The adhesive layer softens when heated and then hardens. Therefore, the sealing process, which is a process of bonding the lid to the electronic component storage package, can be performed by heating the adhesive layer while bringing the lid and the electronic component storage package into contact with each other under a predetermined load. Meanwhile, the base layer is already hardened before the sealing process, so it does not soften even when heated during the sealing process. Therefore, even if a large load is applied in the sealing process to improve yield, the thickness of the sealing portion after the sealing process will not be less than the thickness of the base layer. Therefore, by making the base layer sufficiently thick, the thickness of the sealing portion will also be sufficiently large regardless of the magnitude of the load. Therefore, the stress applied to the sealing portion can be significantly alleviated by deformation of the sealing portion made of a resin adhesive as an elastic-plastic body. Therefore, peeling of the resin adhesive due to stress is suppressed. Therefore, a decrease in airtightness between the electronic component storage package and the lid due to peeling of the resin adhesive is suppressed.

[0003] Japanese Patent Laid-Open Publication No. 2018-056247 (Patent Document 2) discloses an electronic component storage package comprising a flat metal or ceramic heat dissipation substrate, a ceramic or resin frame bonded to the heat dissipation substrate, and a plurality of metal terminals bonded to the frame. The terminals have a nickel plating base film formed on their surfaces and a gold plating film formed on the nickel plating base film. Areas of the terminals that come into contact with a resin adhesive are provided with a nickel oxide coating instead of the gold plating film. According to the publication, providing a nickel oxide coating on the areas of the terminals that come into contact with the resin adhesive enhances the adhesive strength of the resin adhesive on the terminals. Furthermore, in areas not in contact with the resin adhesive, a gold plating film is provided on the nickel plating base film, thereby effectively protecting the metal surface beneath the nickel plating base film from chemical changes such as oxidation, as in the prior art.

[0004] International Publication No. 2018 / 225511 Japanese Patent Application Laid-Open No. 2018-056247

[0005] The aforementioned International Publication No. 2018 / 225511 discloses the use of a sufficiently thick resin adhesive to relieve stress, with the goal of preventing peeling of the resin adhesive. However, it does not take into consideration the need to improve the adhesive strength at the interface between the resin adhesive (adhesive portion) and the package. Meanwhile, the technology disclosed in Japanese Patent Application Laid-Open No. 2018-056247 aims to improve the bonding strength of the resin adhesive on the terminal by providing a nickel oxide coating on the area of ​​the terminal that comes into contact with the resin adhesive. However, this technology can result in the formation of a leak path along the terminal (lead frame) that penetrates the resin adhesive. Specifically, because the lead frame is a relatively thick component, a relatively large surface step is formed on the surface to which the lead frame is attached. This surface step can result in the formation of voids in the resin adhesive. Here, because the lead frame penetrates the resin adhesive that seals the cavity, voids tend to extend to connect the inside and outside of the cavity. Therefore, these voids tend to become leak paths that reduce the airtightness of the cavity.

[0006] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a package, an electronic device, and a method for manufacturing a package that can prevent a decrease in the airtightness of the cavity due to peeling of the adhesive joint that joins the package having a gold-plated portion and the lid to each other.

[0007] Aspect 1 is a package having a cavity to be sealed by attaching a lid using a resin adhesive, comprising: a heat sink; and a frame body made of a ceramic sintered body having a first surface attached to the heat sink and a second surface opposite the first surface, wherein the second surface of the frame body includes an inner region, a middle region, and an outer region separated from the inner region by the middle region, and the package further comprises: a metallization layer having an inner portion, a middle portion, and an outer portion on each of the inner region, the middle region, and the outer region of the second surface of the frame body; a lead frame attached on the outer portion of the metallization layer; and a covering layer made of a ceramic material covering the middle portion of the metallization layer, wherein the lead frame, the inner region of the metallization layer, and the outer region of the metallization layer are gold-plated, and the surface of the covering layer is not gold-plated.

[0008] Aspect 2 is the package according to aspect 1, wherein the covering layer is thinner than the lead frame.

[0009] Aspect 3 is the package according to aspect 1 or 2, wherein the covering layer is only partially disposed around the cavity.

[0010] A fourth aspect of the present invention is the package according to any one of the first to third aspects, wherein the covering layer has a surface provided with convex portions, concave portions, or both convex portions and concave portions.

[0011] Aspect 5 is the package of any one of aspects 1 to 4, wherein the ceramic material of the coating layer comprises a crystalline material.

[0012] Aspect 6 is the package according to any one of aspects 1 to 5, wherein the heat sink is made of a sintered material containing a metal.

[0013] Aspect 7 is an electronic device comprising a package according to any one of aspects 1 to 6, an electronic component mounted on the heat sink within the cavity, a lid attached to the covering layer of the package, and an adhesive portion made of a resin adhesive provided between the covering layer and the lid for attaching the lid to the covering layer of the package.

[0014] Aspect 8 is a method for manufacturing a package for manufacturing a package described in any one of Aspects 1 to 6, comprising the steps of forming a laminate including a first member that becomes the frame body when fired, a second member that is provided on the first member and becomes the metallized layer when fired, and a third member that is provided on the second member and becomes the coating layer when fired, and firing the laminate.

[0015] Aspect 9 is a method for manufacturing a package described in Aspect 8, wherein the laminate includes a fourth member that becomes the heat sink when fired, and the first member in the laminate is provided on the fourth member.

[0016] According to the above-mentioned aspects 1 or 7, first, the covering layer on which the adhesive portion made of a resin adhesive is to be provided is formed in the middle portion of the metallized layer, and the lead frame is not attached to this middle portion. As a result, the lead frame does not penetrate the adhesive portion in a planar layout. This prevents a leak path along the lead frame from forming in the adhesive portion. Second, the adhesive portion that joins the lid and the package having a gold-plated portion to each other can be provided so as to contact the covering layer. Because the covering layer is made of a ceramic material, no gold plating is formed on the surface of the covering layer. As a result, the adhesive portion that joins the covering layer and the lid to each other has high adhesive strength. Therefore, the adhesive portion is less likely to peel off from the package even under temperature cycles. As a result, it is possible to prevent a decrease in the airtightness of the cavity due to the adhesive portion.

[0017] According to the second aspect, the covering layer is thinner than the lead frame, which prevents the thickness of the covering layer from increasing the thickness of the package.

[0018] According to the third aspect, the coating layer is provided only partially around the cavity, which makes it possible to appropriately omit the formation of the coating layer in the region of the second surface of the frame where no metallized layer is present.

[0019] According to the fourth aspect, the coating layer has a surface provided with convex portions, concave portions, or both convex portions and concave portions. This facilitates securing a gas path over the coating layer for a period of time immediately after an uncured or semi-cured resin adhesive is applied to the coating layer to form a bonded portion. This path allows gas in the cavity that expands due to heating for the curing process of the resin adhesive to be discharged to the outside of the cavity. This prevents the gas expanding in the cavity from exerting a large pressure on the uncured or semi-cured resin adhesive after the path is blocked by the subsequent flow of the resin adhesive over time. This prevents the uncured resin adhesive from being disturbed due to this pressure. This prevents the formation of a leak path in the bonded portion due to the disturbance of the uncured resin adhesive. This prevents a decrease in the airtightness of the cavity.

[0020] According to the fifth aspect, the ceramic material of the coating layer contains a crystalline material. This allows the coating layer, the metallized layer, and the frame to be made of a material containing a crystalline material. This makes it easier to form the coating layer, the metallized layer, and the frame by co-firing.

[0021] According to the sixth or ninth aspect, the heat sink is made of a sintered material containing a metal. The heat sink contains a metal, which enhances the thermal conductivity of the heat sink. Furthermore, the heat sink is made of a sintered material, which allows the heat sink to be formed by co-firing together with the frame, the metallized layer, and the coating layer.

[0022] According to the eighth aspect, a step of forming a laminate including portions that will become the metallized layer, the frame, and the covering layer by firing is used, thereby enabling the package to be efficiently manufactured using a co-firing technique.

[0023] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

[0024] 12 is a cross-sectional view schematically showing the configuration of an electronic device having a package according to a first embodiment. FIG. 13 is a partial cross-sectional view taken along line II-II of FIG. 1. FIG. 14 is a cross-sectional view schematically showing the configuration of a package used in manufacturing the electronic device of FIG. 1. FIG. 15 is a partial top view schematically showing the configuration of the package of FIG. 3. FIG. 16 is a cross-sectional view schematically showing a step of a method for manufacturing a package according to the first embodiment. FIG. 17 is a cross-sectional view schematically showing a step of a method for manufacturing a package according to the first embodiment. FIG. 18 is a cross-sectional view schematically showing the configuration of an electronic device having a package of a comparative example. FIG. 19 is a partial cross-sectional view schematically showing the configuration of the electronic device of FIG. 7, taken in a field of view perpendicular to the field of view of FIG. 7. FIG. 19 is a cross-sectional view schematically showing a step of a method for manufacturing a package according to a modified example of the first embodiment. FIG. 19 is a partial cross-sectional view schematically showing a step of a method for manufacturing a package according to a modified example of the first embodiment. FIG. 19 is a top view schematically showing the configuration of a coating layer included in a package according to a second embodiment. FIG. 19 is a partial cross-sectional view schematically showing a step of a method for manufacturing an electronic device using the package according to the second embodiment, taken along line XIII-XIII of FIG. 20. FIG. 21 is a cross-sectional view schematically showing the configuration of a package according to a third embodiment. FIG. 10 is a cross-sectional view schematically showing one step of a method for manufacturing a package according to embodiment 3. FIG. 11 is a cross-sectional view schematically showing one step of a method for manufacturing a package according to embodiment 3. FIG. 12 is a cross-sectional view schematically showing one step of a method for manufacturing a package according to a modified example of embodiment 3. FIG. 13 is a cross-sectional view schematically showing one step of a method for manufacturing a package according to a modified example of embodiment 3. FIG. 14 is a cross-sectional view schematically showing one step of a method for manufacturing a package according to a modified example of embodiment 3.

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that an xyz Cartesian coordinate system is shown in some of the drawings to facilitate understanding of the relative directional relationships between the drawings. Furthermore, in this specification, the term "green" refers to the state before firing. Therefore, a component labeled with the term "green" will be fired, but has not yet been fired. The terms "upper" and "lower" are used merely to distinguish relative directions, and do not imply any limitations related to the direction of gravity unless otherwise specified. The term "metal" can refer to both pure metals and alloys, unless otherwise specified. An alloy can refer to a solid solution of multiple metal components, a mixture of multiple metals that has not been solid-solutioned, or an intermetallic compound.

[0026] First Embodiment Fig. 1 is a cross-sectional view schematically illustrating the configuration of a semiconductor module 100 (electronic device) according to a first embodiment. Fig. 2 is a partial cross-sectional view taken along line II-II (Fig. 1). The semiconductor module 100 includes a package 51, a semiconductor element 8 (electronic component), a lid 80, and an adhesive 70. The semiconductor module 100 may also include wires 9 (wiring members) for electrical connection between the semiconductor element 8 and the package 51.

[0027] 3 and 4 are a cross-sectional view and a partial top view, respectively, schematically illustrating the configuration of a package 51 used in manufacturing the semiconductor module 100. The package 51 has a cavity CV that is sealed by attaching a lid 80 ( FIG. 1 ) using a resin adhesive. The package 51 includes a heat sink 22, a frame 21, a metallized layer 31, a lead frame 30, and a covering layer 40. A gold plating layer (not shown) is formed on the exposed surface of the package 51 made of a metal material by gold plating. On the other hand, a gold plating layer (not shown) is not formed on the exposed surface of the package 51 made of a ceramic material because gold does not adhere to the exposed surface during the gold plating process. Therefore, in the configuration shown in FIG. 3 , a gold plating layer is not formed on the exposed surface of the covering layer 40 or the exposed surface of the frame 21. In other words, a gold plating layer is formed on the exposed surface of the package 51 other than the exposed surface of the covering layer 40 and the exposed surface of the frame 21. Prior to the gold plating process, a base plating process may be performed, in which case a base plating layer (not shown) is provided under the gold plating layer. The base plating is typically nickel plating.

[0028] The semiconductor element 8 ( FIG. 1 ) is mounted on the heat sink 22 ( FIG. 3 ) of the package 51 within the cavity CV of the package 51. The semiconductor element 8 may be attached to the heat sink 22 via a conductive mounting material (not shown). The mounting material may be formed by sintering an Ag conductive paste, which may include a solvent and nano-sized Ag powder dispersed therein. Alternatively, the mounting material may be formed by curing an epoxy resin in which Ag powder is dispersed. Alternatively, the mounting material may be formed by soldering.

[0029] The lid 80 ( FIG. 1 ) is attached to the cover layer 40 of the package 51 by an adhesive 70. The lid 80 may be made of a ceramic material or a resin material. When the lid 80 is made of a ceramic material, the ceramic material may contain alumina as a main component, for example, it is substantially alumina. When the lid 80 is made of a resin material, the resin material may be, for example, a liquid crystal polymer. An inorganic filler may be dispersed in the resin, for example, silica particles. Dispersing the inorganic filler in the resin material can increase the strength and durability of the lid 80.

[0030] The adhesive portion 70 ( FIG. 1 ) is provided between the covering layer 40 and the lid 80 to attach the lid 80 to the covering layer 40 of the package 51. Thus, the adhesive portion 70 contacts the covering layer 40 of the package 51. In the example shown in FIG. 1 , only the covering layer 40 of the package 51 contacts the adhesive portion 70. Thus, in this example, the adhesive strength of the adhesive portion 70 to the package 51 is ensured only at the contact point with the covering layer 40. Alternatively, the adhesive portion 70 may contact other portions of the package 51 in addition to the covering layer 40. For example, the adhesive portion 70 may also contact the inner end of the lead frame 30, the inner portion P1 of the metallization layer 31 (see FIG. 3 ), or both, and these contact points also contribute to the adhesive strength of the adhesive portion 70.

[0031] The adhesive portion 70 is made of a resin adhesive. The resin adhesive may contain an inorganic filler as an additive. During the manufacture of the semiconductor module 100, the resin adhesive is brought into contact with the package 51 in an uncured or semi-cured state and then cured. The resin adhesive may be a thermosetting adhesive. The thermosetting adhesive may contain, for example, an epoxy resin, a phenolic resin, or a silicone resin. Epoxy resin is particularly preferred because it has a good balance of heat resistance, mechanical strength, and chemical resistance. The thickness of the adhesive portion 70 between the lid 80 and the covering layer 40 (the vertical dimension in FIG. 1 ) is, for example, 100 μm or more and 360 μm or less.

[0032] The lead frame 30 is an external terminal of the package 51 and is disposed outside the cavity CV. The exposed surface of the lead frame 30 in Fig. 3 is gold plated. The thickness of the lead frame 30 may be approximately 0.1 mm or more.

[0033] The frame 21 (FIG. 3) has a bottom surface SF1 (first surface) attached to the heat sink 22 and a top surface SF2 (second surface opposite to the first surface). The frame 21 is made of a sintered ceramic body. By using a sintered ceramic body as the material for the frame 21, the heat resistance and insulating properties of the package 51 can be improved. The material for the frame 21 is mainly composed of alumina (Al ２ O ３ ), and may contain a small amount of silica (SiO ２ The raw material powder as the material for the frame 21 may contain, for example, 50 wt % or more of Al as the main component. ２ O ３ powder and SiO ２ The mixed powder may be a powder containing 5 to 17% by weight of Si element in terms of Si content and 3 to 14% by weight of Mn element in terms of MnO content. When the mixed powder is used, the firing temperature is, for example, 1150 to 1300°C.

[0034] The top surface SF2 of the frame 21 includes an inner region R1, a middle region R2, and an outer region R3. The middle region R2 may surround the inner region R1 in a planar layout (a layout parallel to the xy plane). In the planar layout, the outer region R3 is separated from the inner region R1 by the middle region R2.

[0035] The metallized layer 31 has an inner portion P1, a middle portion P2, and an outer portion P3 on the inner region R1, the middle region R2, and the outer region R3, respectively, of the upper surface SF2 of the frame 21. The lead frame 30 is attached to the outer portion P3 of the metallized layer 31 without being attached to the inner portion P1 or the middle portion P2 of the metallized layer 31. Therefore, the lead frame 30 is arranged outside the inner portion P1 and the middle portion P2 of the metallized layer 31 in the planar layout.

[0036] The coating layer 40 is made of a ceramic material. This ceramic material may contain either a crystalline material or a glass material (amorphous material), or both. When the coating layer 40 is formed by co-firing with other ceramic members as described below, the ceramic material of the coating layer 40 preferably contains a crystalline material. In this case, it is preferable that the ceramic material contains a smaller amount of glass material than the crystalline material by weight. The crystalline material is Al ２ O ３ The glass material may contain, for example, at least one selected from the group consisting of silicon oxide, manganese oxide, magnesium oxide, calcium oxide, titanium oxide, and chromium oxide.

[0037] The coating layer 40 covers the middle portion P2 of the metallization layer 31 without covering the inner portion P1 and the outer portion P3 of the metallization layer 31. Therefore, the surfaces (upper surfaces in FIG. 3) of the inner region R1 of the metallization layer 31 (FIG. 3) and the outer region R3 of the metallization layer 31 are gold-plated. On the other hand, the surface (upper surface in FIG. 3) of the coating layer 40 is not gold-plated because the coating layer 40 is made of a ceramic material.

[0038] The covering layer 40 is preferably thinner than the lead frame 30. The thickness of the covering layer 40 may be 5 μm or more and 40 μm or less. In particular, when the covering layer 40 has an approximately flat plate shape as shown in FIG. 3, the thickness of the covering layer 40 is, for example, 5 μm or more and 20 μm or less.

[0039] The covering layer 40 may be provided only partially around the cavity CV, as shown in Fig. 4. In the configuration shown in Fig. 4, the frame 21 extends to form the four sides of a rectangle surrounding the cavity CV, and the covering layer 40 is provided only on the side to which the lead frame 30 is attached (the top side in Fig. 4), and is not provided on the sides to which the lead frame 30 is not attached (the left and right sides in Fig. 4). As a variant, the covering layer 40 may be provided entirely around the cavity CV. In other words, the covering layer 40 may completely surround the cavity CV.

[0040] In this embodiment, the heat sink 22 is made of a sintered material containing a metal as a main component. The sintered material preferably contains copper. In addition to copper, the sintered material may further contain a high-melting-point metal. The high-melting-point metal has a melting point higher than that of copper. The high-melting-point metal may be tungsten, molybdenum, or both. Therefore, the sintered material may contain copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum. The sintered material of the heat sink 22 does not need to contain a non-metal. In other words, the sintered material may be a sintered metal material. In other words, the sintered material may be a sintered material consisting essentially of a metal. Alternatively, the sintered material may contain a ceramic material in addition to or instead of a metal material. For example, the ceramic material may contain at least one selected from the group consisting of silicon oxide, manganese oxide, and zirconium oxide.

[0041] 5 and 6 are cross-sectional views schematically showing a step in the manufacturing method of the package 51 according to the first embodiment.

[0042] Referring to Figure 5, a green laminate CG1 is formed. The green laminate CG1 includes a frame green sheet 21G (first member) that becomes the frame 21 when fired, a metallization paste layer 31G (second member) that becomes the metallization layer 31 when fired, and a ceramic paste layer 40G (third member) that becomes the coating layer 40 when fired. The metallization paste layer 31G is provided on the frame green sheet. The ceramic paste layer 40G is provided on the metallization paste layer 31G. The green laminate CG1 also includes a heat sink green sheet 22G (fourth member) that becomes the heat sink 22 when fired. In the green laminate CG1, the frame green sheet 21G is provided on the heat sink green sheet 22G.

[0043] To form each green sheet, a corresponding slurry is first prepared. The slurry is obtained by mixing powders that will be the components of the sintered body with resin, plasticizer, solvent, etc., using a ball mill. The powder for the slurry to form the frame green sheet 21G is, for example, Al as the main component. ２ O ３ The powder for the slurry for forming the heat sink green sheet 22G is, for example, a metal powder containing copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum. This metal powder may be a mixed powder of a powder containing copper and a powder containing a high-melting-point metal. The powder containing copper may be copper powder. The powder containing a high-melting-point metal may be a high-melting-point metal powder.

[0044] The slurry is typically processed into a green sheet by a doctor blade method. The planar shape of the green sheet is determined according to the shape of the target part. The planar shape may be adjusted by machining such as punching. The planar shape of the heat sink green sheet 22G is usually a substantially rectangular shape. The planar shape of the frame green sheet 21G is a frame-like shape with the portion corresponding to the cavity CV ( FIG. 3 ) removed. Specifically, the frame green sheet 21G is formed as a simple sheet by a doctor blade method, and then the portion corresponding to the cavity CV is removed.

[0045] The metallization paste layer 31G may be formed by printing a metallization paste. The metallization paste is prepared by blending powder of at least one metal selected from the group consisting of tungsten, molybdenum, and copper with additives, resin, solvent, etc., and further adding ceramic powder as needed, followed by kneading. This metallization paste is printed on the frame green sheet 21G by, for example, screen printing. After printing, a drying process is performed, for example, at a temperature of 110°C for 5 minutes. As a modified example, instead of printing the metallization paste layer 31G, a green sheet made of the same material as the metallization paste layer 31G may be laminated.

[0046] The ceramic paste layer 40G may be formed by printing a ceramic paste. The ceramic paste contains the ceramic material of the coating layer 40 described above and an organic solvent such as butyl diglycol acetate. In the ceramic paste, powder of the ceramic material is dispersed in the organic solvent. This ceramic paste is printed on the metallization paste layer 31G by, for example, screen printing. After this printing, a drying process similar to that described above may be performed. As a modified example, instead of printing the ceramic paste layer 40G, a green sheet made of the same material as the ceramic paste layer 40G may be laminated.

[0047] Referring also to FIG. 6 , the green laminate CG1 is fired to obtain a fired body CF1. This results in the frame 21, metallized layer 31, coating layer 40, and heat sink 22 being formed by simultaneous firing. The firing temperature is, for example, 1100°C or higher and 1400°C or higher. A firing temperature of 1100°C or higher allows the green laminate CG1 to be heated to a temperature higher than the melting point of copper. This allows the copper-containing heat sink 22 to be formed with high quality. On the other hand, a firing temperature of 1400°C or lower avoids process difficulties caused by excessively high firing temperatures. For example, excessive evaporation of Cu during firing can be avoided.

[0048] 3, the sintered body CF1 (FIG. 6) is brazed to the lead frame 30. Specifically, a nickel plating process is performed between the outer portion P3 of the metallized layer 31 and the lead frame 30, and then a brazing material layer 32 is formed.

[0049] After the brazing, a base plating process (e.g., nickel plating) is performed, followed by a gold plating process. Prior to these plating processes, unnecessary portions of the brazing material formed in the brazing process may be removed by etching. The gold plating process forms a gold plating layer on the exposed surfaces of the lead frame 30, the metallized layer 31, and the brazing material layer 32. In this embodiment, since the heat sink 22 is primarily composed of metal, a gold plating layer is also formed on the exposed surface of the heat sink. On the other hand, since the coating layer 40 is made of a ceramic material, a gold plating layer is not formed on the exposed surface of the coating layer 40. Therefore, even after the plating process, the surface of the coating layer 40 is made of a ceramic material.

[0050] FIG. 7 is a cross-sectional view schematically illustrating the configuration of a semiconductor module 100Z having a package 51Z of a comparative example. FIG. 8 is a partial cross-sectional view schematically illustrating the configuration of the semiconductor module 100Z of FIG. 7 in a view perpendicular to the view of FIG. 7. In the semiconductor module 100Z, first, the lead frame 30 penetrates the adhesive portion 70 in a planar layout (a layout parallel to the xy plane). Therefore, if a void VD (FIG. 8) is formed in the adhesive portion 70 due to a surface step caused by the lead frame 30, which is a relatively thick member, the void VD (FIG. 8) is likely to extend to connect the inside and outside of the cavity CV (FIG. 7). In this case, the void VD forms a leak path. This leak path reduces the airtightness of the cavity CV. Second, referring to FIG. 7, the interface between the adhesive portion 70 and the lead frame 30 having a gold-plated surface extends to connect the inside and outside of the cavity CV. Because the gold-plated surface is inert, the adhesive strength of the adhesive portion 70 at this interface is likely to be low. Therefore, peeling is likely to occur at this interface. This peeling extends to connect the inside and outside of the cavity CV, forming a leak path. This leak path reduces the airtightness of the cavity CV.

[0051] In contrast, in the package 51 according to the first embodiment, first, the covering layer 40, on which the adhesive portion 70 ( FIG. 1 ) made of a resin adhesive is to be provided, is formed in the middle portion P2 ( FIG. 3 ) of the metallized layer 31, and the lead frame 30 is not attached to this middle portion P2. As a result, the lead frame 30 does not penetrate the adhesive portion 70 ( FIG. 1 ) in a planar layout. This prevents a leak path along the lead frame 30 from being formed in the adhesive portion 70. Second, the adhesive portion 70 ( FIG. 1 ) that bonds the lid 80 and the package 51, which has a gold-plated portion, can be provided so as to contact the covering layer 40. Because the covering layer 40 is made of a ceramic material, no gold plating is formed on the surface of the covering layer 40. As a result, the adhesive portion 70 that bonds the covering layer 40 and the lid 80 to each other has high adhesive strength. Therefore, the adhesive portion 70 is less likely to peel off from the package 51, even under temperature cycling. As a result, it is possible to prevent the adhesive portion 70 from reducing the airtightness of the cavity CV.

[0052] The covering layer 40 may be thinner than the lead frame 30. This prevents the thickness of the covering layer 40 from increasing the thickness of the package 51.

[0053] The covering layer 40 (FIG. 4) may be provided only partially around the cavity CV, thereby making it possible to appropriately omit the formation of the covering layer 40 in the region of the top surface SF2 of the frame 21 where the metallized layer 31 is not present.

[0054] The ceramic material of the coating layer 40 may contain a crystalline material. This allows the materials of the coating layer 40, the metallized layer 31, and the frame 21 to each contain a crystalline material. This makes it easier to form the coating layer 40, the metallized layer 31, and the frame 21 by simultaneous firing.

[0055] The heat sink 22 may be made of a sintered material containing a metal. When the heat sink 22 contains a metal, the thermal conductivity of the heat sink 22 is increased. Furthermore, when the heat sink 22 is made of a sintered material, the heat sink 22 can be formed by co-firing together with the frame 21, the metallized layer 31, and the coating layer 40.

[0056] According to the manufacturing method of the first embodiment, a step of forming a green laminate CG1 ( FIG. 5 ) including portions that will become the metallized layer 31, the frame 21, and the coating layer 40 by firing is performed. This allows the package 51 to be efficiently manufactured using a co-firing technique. In this embodiment, the heat sink 22 is also formed by this co-firing.

[0057] <Modification of Manufacturing Method According to First Embodiment> FIGS. 9 to 11 are cross-sectional views schematically illustrating a step in a manufacturing method for a package 51 according to a modification of the first embodiment. Referring to FIG. 9, a green laminate PG1 is formed. The green laminate PG1 has a structure in which the ceramic paste layer 40G is omitted from the green laminate CG1 (FIG. 5: First Embodiment). Referring further to FIG. 10, the green laminate PG1 (FIG. 9) is fired to obtain a fired body PF1. This results in the frame 21, metallized layer 31, and heat sink 22 being formed by simultaneous firing. Referring to FIG. 11, a ceramic paste layer 40G is formed on the metallized layer 31. The ceramic paste layer 40G may be formed by printing a ceramic paste. The ceramic paste layer 40G on the fired body PF1 is then fired to obtain a fired body CF1 (FIG. 6: First Embodiment). Thereafter, the same steps as those in the first embodiment are performed.

[0058] 12 is a top view schematically showing the configuration of a covering layer 41 of a package 52 (FIG. 13) according to a second embodiment. Fig. 13 is a partial cross-sectional view schematically showing a step of a method for manufacturing a semiconductor module using package 52, taken along line XIII-XIII (FIG. 12).

[0059] Package 52 has the structure of package 51 (FIG. 3: embodiment 1) in which coating layer 41 is applied instead of coating layer 40. In embodiment 2, coating layer 41 has a flat portion 41a (first portion) and a pattern portion 41b (second portion) provided on a part of the surface of flat portion 41a. As a result, coating layer 41 has a surface provided with convex portions. The thickness of flat portion 41a may be 5 μm or more and 20 μm or less. The thickness of pattern portion 41b, in other words, the thickness of the convex portions, may be 5 μm or more and 20 μm or less.

[0060] In the planar layout, the pattern portion 41b may have a pattern in which a plurality of ellipses are arranged, as shown in Fig. 12. The ellipses may be circles. As a modified example, a stripe pattern may be used.

[0061] The layer that will become coating layer 41 after firing may be formed as follows. First, a first paste layer that will become flat portion 41a after firing is printed. A second paste layer that will become pattern portion 41b after firing is printed on the first paste layer. The first and second paste layers are fired simultaneously to form coating layer 41. Similar to coating layer 40 (first embodiment), coating layer 41 may be formed by simultaneous firing with other ceramic members such as metallized layer 31.

[0062] Since the configuration other than the above is substantially the same as that of the first embodiment or its modification, the same or corresponding elements are denoted by the same reference numerals, and description thereof will not be repeated. In addition, the covering layer 41 may be applied to the third embodiment or its modification, which will be described later.

[0063] As a modified example, a portion of the surface of the flat portion 41a may be lowered to provide a recess in the surface of the coating layer. In this case, the thickness of the recess in the coating layer may be 5 μm to 20 μm, and the thickness of the coating layer outside the recess may be 10 μm to 40 μm. As a further modified example, both a protrusion and a recess may be provided on the surface of the coating layer. In this case, the thickness of the recess may be 5 μm to 20 μm, the thickness outside the recess and the protrusion may be 10 μm to 40 μm, and the thickness of the protrusion may be 15 μm to 60 μm.

[0064] According to the second embodiment or its modified example, the coating layer 41 has a surface provided with convex portions, concave portions, or both convex portions and concave portions. This facilitates securing a gas path AP ( FIG. 13 ) passing over the coating layer 41 for a period of time immediately after an uncured or semi-cured resin adhesive is applied to the coating layer 40 to form the adhesive bond 70. This path AP allows gas in the cavity CV that expands due to heating for the curing process of the resin adhesive to be discharged to the outside of the cavity CV. This prevents the gas expanding in the cavity CV from exerting a large pressure on the uncured or semi-cured resin adhesive after the path AP is blocked by the flow of the resin adhesive over time. This prevents the uncured resin adhesive from being disturbed due to this pressure. This prevents the formation of a leak path in the adhesive bond 70 due to the disturbance of the uncured resin adhesive. This prevents a decrease in the airtightness of the cavity CV.

[0065] Third Embodiment FIG. 14 is a cross-sectional view schematically illustrating the configuration of a package 53 according to a third embodiment. In the package 51 of the first embodiment, the frame body 21 and the heat sink 22 are formed by co-firing, so that the frame body 21 and the heat sink 22 are sintered together, and this sintering fixes the frame body 21 and the heat sink 22 to each other. Alternatively, the frame body 21 and the heat sink 22 can be formed separately and then fixed to each other by brazing, and this method is adopted in the third embodiment. Accordingly, the package 53 includes a metallized layer 61 and a brazing material layer 62 in addition to the structure of the package 51 (FIG. 3: first embodiment). The metallized layer 61 is provided on the lower surface SF1 of the frame body 21. The brazing material layer 62 is provided between the metallized layer 61 and the heat sink 22.

[0066] In the third embodiment, as described above, unlike the first embodiment, the heat sink 22 is not formed by simultaneous firing with the frame 21. Therefore, the heat sink 22 does not necessarily need to be made of a sintered material, and may be made of, for example, a metal material that is not a sintered material.

[0067] 15 and 16 are cross-sectional views schematically illustrating a step in the manufacturing method of the package 53 (FIG. 14). Referring to FIG. 15, a green laminate CG2 is formed. The green laminate CG2 has a structure in which the heat sink green sheet 22G is omitted from the green laminate CG1 (FIG. 5: Embodiment 1) and a metallization paste layer 61G is added. The metallization paste layer 61G becomes the metallization layer 61 when fired. Referring further to FIG. 16, the green laminate CG2 (FIG. 15) is fired to obtain a fired body CF2. As a result, the frame 21, the metallization layer 31, the coating layer 40, and the metallization layer 61 are formed by simultaneous firing.

[0068] 14, lead frame 30 and heat sink 22 are attached to sintered body CF2 (FIG. 16) by brazing. Thereafter, a plating process similar to that in the first embodiment is performed to obtain package 53.

[0069] If the heat sink 22 is made of a material that is difficult to braze, such as a ceramic material, a metallized layer (not shown) may be added to the portion of the heat sink 22 that will be brazed (the portion between the heat sink 22 and the brazing material layer 62 in Figure 14).

[0070] <Modification of Manufacturing Method According to Third Embodiment> FIGS. 17 to 19 are cross-sectional views schematically illustrating a step in a manufacturing method of a package 53 according to a modification of the third embodiment. Referring to FIG. 17 , a green laminate PG2 is formed. The green laminate PG2 has a structure in which the ceramic paste layer 40G is omitted from the green laminate CG2 ( FIG. 15 : Third Embodiment). Referring further to FIG. 18 , a fired body PF2 is obtained by firing the green laminate PG2 ( FIG. 17 ). This results in the frame 21, metallization layer 31, and metallization layer 61 being formed by simultaneous firing. Referring to FIG. 19 , a ceramic paste layer 40G is formed on the metallization layer 31. The ceramic paste layer 40G may be formed by printing a ceramic paste. The ceramic paste layer 40G on the fired body PF2 is then fired to obtain a fired body CF2 ( FIG. 16 : Third Embodiment). Thereafter, the same steps as those in the third embodiment are performed.

[0071] 8: Semiconductor element 21: Frame 21G: Frame green sheet (first member) 22: Heat sink 22G: Heat sink green sheet (fourth member) 30: Lead frame 31: Metallized layer 31G: Metallized paste layer (second member) 32: Brazing material layer 40, 41: Coating layer 40G: Ceramic paste layer (third member) 41a: Flat portion 41b: Pattern portion 51-53: Package 70: Adhesive portion 80: Lid 100: Semiconductor module CF1, CF2: Fired body CG1, CG2: Green laminated body CV: Cavity P1: Inner portion P2: Middle portion P3: Outer portion PF1, PF2: Fired body PG1, PG2: Green laminated body R1 : Inner area R2 : Middle area R3 : Outer area SF1 : Bottom surface (first surface) SF2 : Top surface (second surface)

Claims

1. A package having a cavity to be sealed by attaching a lid using a resin adhesive, comprising: a heat sink; and a frame made of a ceramic sintered body, having a first surface attached to the heat sink and a second surface opposite to the first surface, wherein the second surface of the frame includes an inner region, an intermediate region, and an outer region separated from the inner region by the intermediate region, and the package further includes: a metallized layer having an inner portion, an intermediate portion, and an outer portion on each of the inner region, the intermediate region, and the outer region of the second surface of the frame; a lead frame attached on the outer portion of the metallized layer; and a coating layer made of a ceramic material covering the intermediate portion of the metallized layer, wherein the lead frame, the inner region of the metallized layer, and the outer region of the metallized layer are gold-plated, and the surface of the coating layer is not gold-plated.

2. The package according to claim 1, wherein the coating layer is thinner than the lead frame.

3. The package according to claim 1 or 2, wherein the coating layer is provided only partially around the cavity.

4. The package according to claim 1 or 2, wherein the coating layer has a surface provided with a convex portion, a concave portion, or both a convex portion and a concave portion.

5. The package according to claim 1 or 2, wherein the ceramic material of the coating layer contains a crystalline material.

6. The package according to claim 1 or 2, wherein the heat sink is made of a sintered material containing a metal.

7. An electronic device comprising: the package according to claim 1 or 2; an electronic component mounted on the heat sink within the cavity; a lid attached to the coating layer of the package; and an adhesive portion made of a resin adhesive provided between the coating layer and the lid for attaching the lid to the coating layer of the package.

8. A method for manufacturing a package for manufacturing the package according to claim 1 or 2, comprising: forming a laminate including a first member that becomes the frame by being fired, a second member provided on the first member and becoming the metallized layer by being fired, and a third member provided on the second member and becoming the coating layer by being fired; and firing the laminate.

9. The method for manufacturing a package according to claim 8, wherein the laminate includes a fourth member that becomes the heat sink by being fired, and in the laminate, the first member is provided on the fourth member.

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