JP2023082392A - package - Google Patents

Abstract

To provide a package capable of suppressing the occurrence of delamination at the interface between layers due to thermal stress in a heat sink exposed to a large temperature change when a frame is joined.SOLUTION: A first layer 11a of a heat sink 10 has a first surface S1 and a second surface S2 that are opposite to each other in the thickness direction, and forms a first side portion H1a included in a side surface H3 of the heat sink 10. A second layer 12a of the heat sink 10 is laminated on the first surface S1 and forms a second side portion H2a included in the side surface H3 of the heat sink 10. A third layer 12b of the heat sink 10 is laminated on the second surface S2 and forms a third side portion H2b included in the side surface H3 of the heat sink 10. The first surface S1 includes a first flat portion SF1 away from the side surface H3 of the heat sink 10, and a first end portion SG1 slanted from the first flat portion SF1 so as to reach the side surface H3 of the heat sink 10 and bite into the second layer 12a.SELECTED DRAWING: Figure 2

Description

The present invention relates to packages, and more particularly to packages having a cavity to be sealed by a lid.

Packages having cavities are often used to house electronic components such as power semiconductor devices. After the electronic component is mounted in the cavity of the package, the cavity is hermetically sealed by bonding the lid to the package. This provides an electronic device having electronic components protected from the external environment. Packages for power semiconductor devices often have heat sinks. The bottom surface of the heat sink (the surface opposite to the surface on which the electronic components are mounted) is usually attached to a supporting member that supports it. The support member is, for example, a mounting board or a heat dissipation member. The support member is brought into thermal contact with the bottom surface of the heat sink. Through the heat sink, heat from the electronic component is efficiently discharged to the outside of the package (typically to the support member). Thereby, the temperature rise of the electronic component is suppressed to about 150° C., for example.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 2003-282751 (Patent Document 1), a Cu or Cu-based metal plate is used as a heat sink. Cu is inexpensive and has a high thermal conductivity exceeding 300 W/m·K. Therefore, the heat dissipation performance of the heat sink can be improved while suppressing the material cost of the heat sink. According to this technique, first, a semiconductor element is mounted on a heat sink by brazing. Next, a frame to which external connection terminals are bonded in advance is bonded onto the heat sink so as to surround the semiconductor element. By using a low-melting-point bonding material for this bonding, the frame is bonded at a temperature lower than the brazing temperature of the semiconductor element. Next, the cavity is sealed by joining a cover to the upper surface of the frame. An electronic device is thus obtained.

Japanese Patent Laying-Open No. 2005-243819 (Patent Document 2) discloses that a clad material, specifically CPC (registered trademark), is used for a heat sink. CPC is a composite metal plate (composite material) having a Cu—Mo alloy layer and Cu layers provided above and below it. The coefficient of linear expansion of CPC is lower than that of Cu. Therefore, by using CPC instead of Cu as a heat sink material, the coefficient of linear expansion of the heat sink can be made close to that of ceramic.

According to Japanese Patent Application Laid-Open No. 2010-219441 (Patent Document 3), an electronic component housing package has a heat sink made of a clad material, a frame, and external connection terminals. The frame is made of ceramic such as alumina or aluminum nitride. Metallized films made of tungsten, molybdenum, or the like are formed on both surfaces of the frame. Using a brazing material such as Ag--Cu brazing material, the radiator plate and the external connection terminals are bonded to both sides of the frame via metallized films. The clad material is formed by alternately laminating copper layers and molybdenum layers having a thickness of 0.2 mm or less in a total of five or more layers, and the copper layer constitutes the outermost layer. The total thickness ratio of the molybdenum layer to the heat sink is 10-14%. According to the above publication, this configuration has the effect that the thermal conductivity of the radiator plate does not decrease significantly, and only the coefficient of thermal expansion decreases.

Japanese Patent Application Laid-Open No. 2003-282751 JP 2005-243819 A JP 2010-219441 A

A method of manufacturing a package usually includes a step of bonding a frame to a heat sink using a bonding material. This step usually requires heating, and a high temperature of about 800° C., for example, is required particularly when the bonding material is a brazing material. The heat sink is thus exposed to large temperature variations as the bonding material is formed. As a result, large thermal stresses are applied in the heat sink. When the large thermal stress described above is applied to a heat sink having an interface between layers, such as a heat sink made of a clad material, peeling tends to occur starting from the edge of the interface between layers. This delamination can result in unacceptable damage to the heat sink.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an interface between layers caused by thermal stress in a heat sink that is exposed to large temperature changes when frames are joined. It is an object of the present invention to provide a package capable of suppressing the occurrence of peeling.

The package has a cavity to be sealed by a lid. The package includes a frame, a heat sink, and a first bonding material. The frame is made of an insulator and surrounds the cavity in plan view. The heat sink has a support surface that supports the frame, a bottom surface that is opposite to the support surface in the thickness direction perpendicular to the plan view, and side surfaces that connect the support surface and the bottom surface. The first bonding material bonds the frame and the heat sink to each other. The heat sink comprises a first layer of a first metallic material, a second layer of a second metallic material different from the first metallic material, and a third metallic material different from the first metallic material. and a third layer consisting of The first layer has a first surface and a second surface opposite to each other in the thickness direction, and forms a first side included in the side surface of the heat sink. The second layer is laminated directly to the first side of the first layer and forms a second side included in the side of the heat sink. A third layer is laminated directly to the second side of the first layer and forms a third side included in the side of the heat sink. In a cross-sectional view parallel to the thickness direction, the first surface of the first layer includes a first flat portion perpendicular to the thickness direction and away from the side surface of the heat sink, a side surface of the heat sink, and a second layer. a first end angled from the first flat portion to cut into.

According to one embodiment of the package, the first surface of the first layer includes a first edge that is angled from the first flat portion to cut into the second layer. As a result, the edge of the interface between the first flat portion of the first layer and the second layer is covered with the first layer in the in-plane direction. Therefore, the occurrence of delamination at the interface between the first layer and the second layer due to thermal stress in the heat sink exposed to large temperature changes when the first bonding material is formed is suppressed. can do.

The second surface of the first layer includes, in a cross-sectional view, a second flat portion that is perpendicular to the thickness direction and away from the side surface of the heat sink, and a second flat portion that reaches the side surface of the heat sink and bites into the third layer. and a second end that is slanted from the flat portion. In that case, the edge of the interface between the second flat portion of the first layer and the third layer is covered with the first layer in the in-plane direction. Therefore, it is possible to suppress the occurrence of delamination at the interface between the first layer and the third layer due to thermal stress in the heat sink.

At the side of the heat sink, the first side of the first layer has a recessed portion recessed relative to the second side of the second layer and the third side of the third layer. good. In that case, the portion of the first layer that covers the edge of the interface between the first flat portion of the first layer and the second layer in the in-plane direction is formed using a material suitable for the recessed portion. can do.

The concave portion of the first side portion of the first layer may be positioned only outside the first flat portion of the first layer in the direction perpendicular to the thickness direction in cross-section. In that case, breakage of the heat sink due to the concave portion can be sufficiently avoided.

The first metallic material may be harder than the second metallic material and the third metallic material. In that case, the portion of the first layer that covers the edge of the interface between the first flat portion of the first layer and the second layer in the in-plane direction is made of a hard material. Therefore, it is possible to further suppress the occurrence of delamination at the interface between the first layer and the second layer due to thermal stress in the heat sink.

The second metallic material and the third metallic material may be the same. In that case, the material configuration of the heat sink can be simplified.

The first layer may be thinner than each of the second and third layers. In that case, a relatively thin layer can be used as the layer covering the interlayer interface of the heat sink in the in-plane direction.

The frame insulator may be a ceramic insulator. In that case, the frame has high heat resistance. Therefore, the first bonding material can be formed at a high temperature. Even if a large thermal stress is applied to the heat sink along with this, it is possible to suppress the occurrence of peeling at the interface between the first layer and the second layer for the reason described above.

The first joining material may be made of brazing material. In that case, a high temperature is required to form the first bonding material. Even if a large thermal stress is applied to the heat sink along with this, it is possible to suppress the occurrence of peeling at the interface between the first layer and the second layer for the reason described above.

The package may further include metal leads for obtaining electrical connections between the interior and exterior of the cavity and a second bonding material. The metal leads are supported by the frame. The second joining material joins the frame and the metal leads to each other. In this case, even if the heat sink is exposed to temperature changes when the second bonding material is formed, for the reasons described above, thermal stress in the heat sink may cause the first layer and the second layer to separate. It is possible to suppress the occurrence of delamination at the interface between.

Objects, features, aspects and advantages of the present invention will become more apparent with the following detailed description and accompanying drawings.

1 is a schematic perspective view showing the configuration of an electronic device according to an embodiment, partly omitted so that the inside of a cavity can be seen; FIG. 2 is a schematic cross-sectional view along line II-II of the electronic device of FIG. 1; FIG. 3 is a schematic cross-sectional view showing the configuration of a package as a component of the electronic device of FIG. 2; FIG. FIG. 4 is a partially enlarged view of FIG. 3 and a partial cross-sectional view schematically showing the configuration of the heat sink; FIG. 5 is a partially enlarged view of FIG. 4; 6 is an example of a micrograph corresponding to FIG. 5; It is a fragmentary sectional view showing roughly the formation method of the side of a heat sink.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below based on the drawings. Some figures are shown in xyz Cartesian coordinates to facilitate understanding of orientation relationships between figures. In this specification, metal can mean either a pure metal or an alloy unless otherwise specified. Planar view means projection onto a plane perpendicular to the thickness direction. In other words, the thickness direction is the direction perpendicular to the plan view. According to the xyz coordinate system, the thickness direction corresponds to the z direction, and the plane perpendicular to the thickness direction corresponds to the xy plane.

FIG. 1 is a schematic perspective view showing the configuration of an electronic device 90 according to this embodiment. FIG. 2 is a schematic cross-sectional view of electronic device 90 of FIG. 1 along line II-II. Electronic device 90 includes package 50 , lid 80 , and electronic component 8 . The electronic device 90 may also have an adhesive layer 70 . Further, the electronic device 90 may have wires 9 (wiring members). 1, the illustration of the lid 80 and the adhesive layer 70 is partially omitted so that the inside of the cavity CV of the package 50 can be partially seen. The electronic component 8 may be a power semiconductor element, in which case the electronic device 90 is a power module. The power semiconductor device may be for radio frequency (RF) applications, in which case the electronic device 90 is an RF power module. Although one electronic component 8 is illustrated in FIGS. 1 and 2 , a plurality of electronic components 8 may be mounted on the package 50 .

FIG. 3 is a schematic cross-sectional view showing the configuration of the package 50 as a component of the electronic device 90 (FIG. 2). When the package 50 is prepared for manufacturing the electronic device 90, the electronic components 8 are not yet mounted as shown in FIG. The package 50 has a cavity CV to be sealed by a lid 80 (FIG. 2). Package 50 includes frame 20 , heat sink 10 , and first bonding material 21 . Package 50 further includes metal leads 30 (metal terminals) and a second bonding material 22 in this embodiment.

The frame 20 surrounds the cavity CV in plan view. The frame 20 is made of an insulator. This insulator is in particular a ceramic insulator, for example substantially alumina. The ceramic insulator may be zirconia. In order to facilitate bonding with the first bonding material 21 and the second bonding material 22, the parts of the surface of the frame 20 facing the first bonding material 21 and the second bonding material 22 are: A metallization film (not shown) may be provided. The outer edge of the frame 20 may have a rectangular shape as shown in FIG. 1, and the size of each side is, for example, 10 mm or more and 40 mm or less. The thickness of the frame 20 is, for example, 0.25 mm or more and 1.25 mm or less. If the thickness of the frame 20 is less than 0.25 mm, the height of the cavity CV is likely to be insufficient. If the thickness of the frame 20 is greater than 1.25 mm, the length of the wire 9 (FIG. 2) that needs to be connected to the metal lead 30 on the frame 20 will also increase, resulting in an increase in the inductance of the wire 9 . An increase in the inductance of the wire 9 is usually undesirable due to its electrical properties.

The heat sink 10 has a support surface H1 that supports the frame 20, a bottom surface H2 that is opposite to the support surface H1 in the z direction (thickness direction perpendicular to the plan view), and a side surface H3 that connects the support surface H1 and the bottom surface H2. ,have. Details of the structure of the heat sink 10 will be described later.

A first bonding material 21 bonds the frame 20 and the heat sink 10 to each other. The first bonding material 21 is made of brazing material. This brazing filler metal may be a brazing filler metal containing silver, ie, a silver brazing filler metal, and has a melting point of, for example, 650° C. or higher and 950° C. or lower. The thickness of the first bonding material 21 may be smaller than the thickness of each of the frame 20 and the heat sink 10 .

The metal lead 30 is for obtaining electrical connection between the inside and outside of the cavity CV. Metal leads 30 are supported by frame 20 . The material of the metal lead 30 is Fe—Ni alloy, Cu, or Cu alloy, for example. An Fe—Ni alloy is, for example, 42 alloy. The 42 alloy contains Fe atoms as the main component and about 42 wt% (weight percent) Ni atoms.

The second bonding material 22 bonds the frame 20 and the metal leads 30 to each other. The second bonding material 22 is made of brazing material. This brazing filler metal may be a brazing filler metal containing silver, ie, a silver brazing filler metal, and has a melting point of, for example, 650° C. or higher and 950° C. or lower. The material of the second bonding material 22 may be the same as the material of the first bonding material 21 . The thickness of the second bonding material 22 may be smaller than the thickness of each of the frame 20 and the metal leads 30 .

FIG. 4 is a partially enlarged view of FIG. 3 and a partial cross-sectional view schematically showing the configuration of the heat sink 10. As shown in FIG. 5 is a partially enlarged view of FIG. 4. FIG. FIG. 6 is an example of a micrograph corresponding to FIG.

The heat sink 10 is a clad material having a laminated structure of at least three layers. In this embodiment, the heat sink 10 is a clad material having a five-layer laminated structure. 4 layers 11b and a fifth layer 12c.

Each of the first layer 11a, the second layer 12a, and the third layer 12b included in the heat sink 10 as described above is made of the first metal material, the second metal material, and the third metal material. Become. Each of the second metallic material and the third metallic material is different than the first metallic material. The first metallic material may be harder than the second metallic material and the third metallic material. The second metallic material and the third metallic material may be the same. In the present embodiment, the first metal material is substantially Mo (molybdenum), and each of the second metal material and the third metal material is substantially Cu (copper). Therefore, hereinafter, the first layer 11a, the second layer 12a, and the third layer 12b may be referred to as the Mo layer 11a, the Cu layer 12a, and the Cu layer 12b, respectively. Mo layer 11a may be thinner than each of Cu layer 12a and Cu layer 12b. In this embodiment, the Cu layer 12a forms the support surface H1 of the heat sink 10. As shown in FIG.

Also, as described above, the fourth layer 11b and the fifth layer 12c included in the heat sink 10 are made of the fourth metal material and the fifth metal material, respectively. Each of the third metallic material and the fifth metallic material is different than the fourth metallic material. The fourth metallic material may be harder than the third metallic material and the fifth metallic material. The third metallic material and the fifth metallic material may be the same. In this embodiment, the fourth metal material is substantially Mo and the fifth metal material is substantially Cu. Therefore, hereinafter, the fourth layer 11b and the fifth layer 12c may be referred to as the Mo layer 11b and the Cu layer 12c, respectively. Mo layer 11b may be thinner than each of Cu layer 12b and Cu layer 12c. In this embodiment, the Cu layer 12c forms the bottom surface H2 of the heat sink 10. As shown in FIG.

The Mo layer 11a has a surface S1 (first surface) and a surface S2 (second surface) opposite to each other in the z-direction, and a side portion H1a (first side) included in the side surface H3 of the heat sink 10. part). The Cu layer 12a is laminated directly on the surface S1 of the Mo layer 11a and forms a side portion H2a (second side portion) included in the side surface H3 of the heat sink 10. As shown in FIG. In the cross-sectional views of FIGS. 4 and 5, the side portion H2a may be substantially regarded as a straight portion parallel to the z-direction. The Cu layer 12b is laminated directly on the surface S2 of the Mo layer 11a and forms a side portion H2b (third side portion) included in the side surface H3 of the heat sink 10. As shown in FIG. In cross-sectional views of FIGS. 4 and 5, the side portion H2b may be substantially regarded as a straight portion parallel to the z-direction. This straight line may be defined by fitting a straight line parallel to the z-direction, if desired, to a photograph such as that of FIG. The surface S1 of the Mo layer 11a is perpendicular to the z-direction and separated from the side surface H3 of the heat sink 10 in FIGS. , and an end portion SG1 (first end portion) inclined from the flat portion SF1 so as to reach the side surface H3 of the heat sink 10 and bite into the Cu layer 12a. A surface S2 of the Mo layer 11a reaches a flat portion SF2 (second flat portion) perpendicular to the z-direction and away from the side surface H3 of the heat sink 10 and the side surface H3 of the heat sink 10 in a cross-sectional view, and the Cu layer 12b. and an end portion SG2 (second end portion) inclined from the flat portion SF2 so as to bite into. Each dimension of end SG1 and end SG2 in the z-direction (dimension in the vertical direction in FIGS. 4 and 5) is, for example, 5 μm or more and 100 μm or less.

On the side surface H3 of the heat sink 10, the side portion H1a of the Mo layer 11a has a concave portion recessed with respect to the side portion H2a of the Cu layer 12a and the side portion H2b of the Cu layer 12b. In other words, the side portion H1a of the Mo layer 11a has a concave portion recessed with respect to the virtual plane VF (FIG. 5) including the side portions H2a and H2b. The concave portion of the side portion H1a of the Mo layer 11a is located only outside the flat portion SF1 of the Mo layer 11a in the x direction. Here, the x-direction is a direction perpendicular to the thickness direction (z-direction) in the cross-sectional view (field of view of the zx plane) shown in FIGS. The depth of this concave portion in the x-direction is, for example, 1 μm or more and less than 10 μm.

Mo layer 11 b ( FIG. 4 ) has surfaces S 3 and S 4 opposite to each other in the z-direction, and forms side portion H 1 b included in side surface H 3 of heat sink 10 . The Cu layer 12b is laminated directly on the surface S3 of the Mo layer 11b. The Cu layer 12c is laminated directly on the surface S4 of the Mo layer 11b and forms a side portion H2c included in the side surface H3 of the heat sink . In a cross-sectional view (FIG. 4), the side portion H2c may be substantially regarded as a straight portion parallel to the z-direction. This straight line may be defined by fitting a straight line parallel to the z-direction, if desired, to a photograph such as that of FIG. In FIG. 4 (cross-sectional view parallel to the z-direction), the surface S3 of the Mo layer 11b reaches a flat portion SF3 that is perpendicular to the z-direction and away from the side surface H3 of the heat sink 10 and the side surface H3 of the heat sink 10 and Cu and an end portion SG3 slanted from the flat portion SF3 so as to cut into the layer 12b. The surface S4 of the Mo layer 11b has, in a cross-sectional view, a flat portion SF4 that is perpendicular to the z-direction and away from the side surface H3 of the heat sink 10, and a flat portion SF4 that reaches the side surface H3 of the heat sink 10 and bites into the Cu layer 12c. and ends SG4 sloping from. The dimension of each of the ends SG3 and SG4 in the z-direction (dimension in the vertical direction in FIG. 4) is, for example, 5 μm or more and 100 μm or less. The end SG3 of the Mo layer 11b may be separated from the end SG2 of the Mo layer 11a.

On the side surface H3 of the heat sink 10, the side portion H1b of the Mo layer 11b has a concave portion recessed with respect to the side portion H2b of the Cu layer 12b and the side portion H2c of the Cu layer 12c. The concave portion of the side portion H1b of the Mo layer 11b is located only outside the flat portion SF3 of the Mo layer 11b in the x direction. Here, the x direction is a direction perpendicular to the thickness direction (z direction) in the cross-sectional view (zx plane view) shown in FIG. The depth of this concave portion in the x-direction is, for example, 1 μm or more and less than 10 μm.

In a cross-sectional view (FIG. 5), the surface S1 has a boundary point BN1 between the flat portion SF1 and the end portion SG1, and the surface S2 has a boundary point BN2 between the flat portion SF2 and the end portion SG2. have. FIG. 5 shows an example in which surfaces S1 and S2 are locally bent at boundary points BN1 and BN2, respectively. In other words, each of end SG1 and end SG2 is an example in which each is a substantially flat surface inclined from the z-direction. The angle formed by the flat portion SF1 and the end portion SG1 at the boundary point BN1 may be 100° to 175°. The angle formed by the flat portion SF2 and the end portion SG2 at the boundary point BN2 may also be 100° to 175°. However, the ends SG1 and SG2 are not limited to flat surfaces, and may be curved surfaces inclined from the z-direction. This curved surface may be convex or concave.

Further, in a cross-sectional view (FIG. 5), the end of the flat portion SF1 may be positioned within 10 μm from the point VL1. Here, the point VL1 is the intersection of a line extending the side portion H2a of the Cu layer 12a along the z direction and a line extending the flat portion SF1 along the x direction. Similarly, the end of flat portion SF2 may be located within 10 μm from point VL2. Here, the point VL2 is the intersection of a line extending the side portion H2b of the Cu layer 12b along the z direction and a line extending the flat portion SF2 along the x direction. A concave portion of the side portion H1a of the Mo layer 11a is located between the boundary point BN1 and the point VL1. A concave portion of the side portion H1a of the Mo layer 11a is located between the boundary point BN2 and the point VL2.

FIG. 7 is a partial cross-sectional view schematically showing a method of forming the side surface H3 of the heat sink 10. As shown in FIG. First, a clad material 10P as a material of the heat sink 10 is formed. The heat sink 10 (FIG. 4) is formed by cutting from the clad material 10P (FIG. 7) as indicated by the two-dot chain line (FIG. 7). Therefore, the size of the clad material 10P is larger than that of the heat sink 10 in the xy in-plane direction (the in-plane direction perpendicular to the thickness direction). If the clad material 10P is sufficiently large, a plurality of heat sinks 10 can be cut out from one clad material 10P. The layered structure of the clad material 10P is the same as the layered structure of the heat sink 10 (FIG. 4) in a region sufficiently distant from the side surface H3.

By appropriately selecting the cutting method when cutting the clad material 10P along the two-dot chain line (FIG. 7), the Mo layer 11a to the Cu layer 12a and the Mass transfer to the Cu layer 12b can be sufficiently generated. In order to sufficiently generate this mass transfer, for example, while adopting a dicing process (in other words, a cutting method by pressing a rotary blade that rotates at high speed), processing conditions such as the shape of the rotary blade, material, and rotation speed are set. adjusted accordingly. Generally, the processing conditions for dicing are adjusted so as to suppress material transfer on the cut surface as much as possible. adjusted to

As a result of the above cutting, as shown in FIG. 5, on the side surface H3 of the heat sink 10, the above-described concave portion is formed in the side portion H1a of the Mo layer 11a, and the Cu layer 12a and the Cu layer 12b are formed respectively. An end portion SG1 and an end portion SG2 that bite into are formed. Therefore, the region of the clad material 10P that becomes the concave portion of the heat sink 10 after cutting can be used as a material for the Mo layer 11a to bite into the Cu layers 12a and 12b of the heat sink 10. FIG.

As a modification, pressing (in other words, a cutting method in which a fixed blade is pressed) may be used instead of dicing, and processing conditions such as the shape, material, and speed of the fixed blade may be appropriately adjusted. In this case, only one of the end portion SG1 and the end portion SG2 is formed in the Mo layer 11a. For example, when the fixed blade moves from bottom to top in FIG. 7, the edge SG1 (FIG. 5) is formed, but the edge SG2 (FIG. 5) is not formed, and instead of the edge SG2, a flat blade is formed. An end portion extending on the same plane as the portion SF2 is formed. Therefore, when it is necessary to form both the end portion SG1 and the end portion SG2, dicing is preferable to pressing.

Next, an example of a method for manufacturing the electronic device 90 will be described below.

A package 50 (FIG. 3) is provided. Electronic component 8 is mounted on support surface H1 of heat sink 10 of package 50 . This mounting may be done by soldering. In other words, a solder material may be used as the mounting material for mounting the electronic component 8 . Electronic component 8 is then electrically connected to metal leads 30 by wires 9 . Wires 9 may be formed by wire bonding.

A lid 80 (FIGS. 1 and 2) is prepared. The lid 80 may be made of a ceramic material, which may contain alumina as a main component, eg substantially alumina. Alternatively, the lid body 80 may contain resin. The resin is, for example, liquid crystal polymer. An inorganic filler may be dispersed in the resin, and the inorganic filler is, for example, silica particles. By dispersing the inorganic filler in the resin, the strength and durability of the lid 80 can be enhanced.

Next, the lid 80 is placed via the adhesive layer 70 on the frame 20 provided with the metal leads 30 . The adhesive layer 70 contains a thermosetting resin in this example, and is in a semi-cured state at the time of placement. The adhesive layer 70 is provided on the frame 20 so as to surround the cavity CV. The adhesive layer 70 may have a portion provided on the frame 20 via the metal lead 30, as shown in FIG. The thickness of the adhesive layer 70 between the lid 80 and the package 50 is, for example, 100 μm or more and 360 μm or less. The lid 80 (FIG. 2) may have an inner surface 81i facing the cavity CV and an opposite outer surface 81o. A frame portion 81p, which is a protrusion having a substantially corresponding frame shape, is provided. In this case, the adhesive layer 70 is in contact with the frame portion 81p.

Next, the lid body 80 is pressed against the frame body 20 with a predetermined load. A suitable load depends on the dimensional design of the package 50, but is, for example, about 500 g or more and 1 kg or less. The adhesive layer 70 is heated while being pressed with a load. The heated adhesive layer 70 first changes to a softened state. This reduces the viscosity of the adhesive layer 70 . As a result, the adhesive layer 70 is wetted and spread. After that, the adhesive layer 70 changes into a hardened state as the curing reaction by heating progresses, and as a result, the adhesive layer 70 bonds the lid body 80 and the frame body 20 to each other.

The adhesive layer 70 may contain at least one of epoxy resin, phenol resin and silicone resin as a main component. Epoxy resins are particularly preferred because they have well-balanced heat resistance, mechanical strength and chemical resistance. In order to preferably have these characteristics, the content of the epoxy resin as the main component is preferably 20 to 40 wt%, and the balance may be composed of subcomponents such as a curing agent. Specifically, the subcomponents include, for example, 1 to 10 wt% curing agent, 50 to 70 wt% inorganic filler, 0.5 to 2 wt% coupling agent, and 0.5 to 2 wt% catalyst. and 0.1-5 wt % of a low stress agent. A phenoxy resin compound may be used as a curing agent. Silica may be used as the inorganic filler. Organic phosphorus or boron salts may be used as catalysts. Silicone may be used as a low stress agent. The adhesive layer 70 may have a bending elastic modulus smaller than that of the lid 80 .

As described above, as shown in FIGS. 1 and 2, a configuration is obtained in which the lid 80 seals the cavity CV. In other words, electronic device 90 (FIGS. 1 and 2) is obtained. The bottom surface H2 (FIG. 2) of the heat sink 10 of the electronic device 90 is attached to a support member (not shown). The support member is, for example, a mounting board or a heat dissipation member. The heat sink 10 may have penetrations (not shown) through which fasteners (eg, screws) for attachment to a support member pass.

According to the present embodiment, surface S1 (FIG. 5) of Mo layer 11a includes end portion SG1 inclined from flat portion SF1 so as to bite into Cu layer 12a. As a result, the edge of the interface between the flat portion SF1 of the Mo layer 11a and the Cu layer 12a (boundary point BN1 in FIG. 5) is covered with the Mo layer 11a in the in-plane direction (x direction in FIG. 5). Therefore, delamination at the interface between the Mo layer 11a and the Cu layer 12a due to thermal stress in the heat sink 10 exposed to large temperature changes when the first bonding material 21 (FIG. 3) is formed can be suppressed.

The surface S2 of the Mo layer 11a reaches the flat portion SF2 perpendicular to the thickness direction and away from the side surface H3 of the heat sink 10 and the side surface H3 of the heat sink 10 in a cross-sectional view (FIG. 5) so as to cut into the Cu layer 12b. and an end portion SG2 inclined from the flat portion SF2. As a result, the edge of the interface between the flat portion SF2 of the Mo layer 11a and the Cu layer 12b (boundary point BN2 in FIG. 5) is covered with the Mo layer 11a in the in-plane direction (x direction in FIG. 5). Therefore, the occurrence of peeling at the interface between the Mo layer 11a and the Cu layer 12b due to the thermal stress in the heat sink 10 can be suppressed.

On the side H3 of the heat sink 10, the side H1a (FIG. 5) of the Mo layer 11a has a concave portion recessed with respect to the side H2a of the Cu layer 12a and the side H2b of the Cu layer 12b. As a result, the portion of the Mo layer 11a that covers the end (boundary point BN1) of the interface between the flat portion SF1 of the Mo layer 11a and the Cu layer 12a in the in-plane direction (the x direction in FIG. 5) is formed into a concave portion. It can be formed using a material that meets the requirements. In addition, the portion of the Mo layer 11a that covers the end (boundary point BN2) of the interface between the flat portion SF2 of the Mo layer 11a and the Cu layer 12b in the in-plane direction (the x direction in FIG. 5) is formed as a concave portion. It can be formed using existing materials.

The concave portion of the side portion H1a of the Mo layer 11a is located only outside the flat portion SF1 of the Mo layer 11a in the direction perpendicular to the thickness direction (z direction) in cross-sectional view (FIG. 5), that is, in the x direction. there is This can sufficiently prevent the heat sink 10 from being damaged due to the concave portion.

The first metal material forming the first layer (Mo layer) 11a is the second metal material and the third metal material forming the second layer (Cu layer) 12a and the third layer (Cu layer) 12b, respectively. Harder than metal materials. As a result, the end (boundary point BN1) of the interface between the flat portion SF1 of the first layer (Mo layer) 11a and the second layer (Cu layer) 12a of the first layer (Mo layer) 11a is The portion covered in the in-plane direction (the x-direction in FIG. 5) is made of a hard material. Therefore, the occurrence of delamination at the interface between the first layer (Mo layer) 11a and the second layer (Cu layer) 12a due to thermal stress in the heat sink 10 can be further suppressed. . In the first layer (Mo layer) 11a, the end of the interface (boundary point BN2) between the flat portion SF2 of the first layer 11a (Mo layer) and the third layer (Cu layer) 12b is the plane. The part covering in the inward direction (x direction in FIG. 5) consists of a hard material. Therefore, the occurrence of delamination at the interface between the first layer (Mo layer) 11a and the third layer (Cu layer) 12b due to thermal stress in the heat sink 10 can be further suppressed. . If the above-mentioned relationship of hardness is expressed using Vickers hardness, it will be as follows. The first metal material forming the first layer (Mo layer) 11a is the second metal material and the third metal material forming the second layer (Cu layer) 12a and the third layer (Cu layer) 12b, respectively. It has a higher Vickers hardness than metal materials. As an example of typical Vickers hardness, Mo has a Vickers hardness of 1530 MPa, and Cu has a Vickers hardness of 369 MPa, the former being larger.

The second metallic material and the third metallic material are the same, eg both are substantially Cu. Thereby, the material configuration of the heat sink 10 can be simplified.

Mo layer 11a is thinner than each of Cu layer 12a and Cu layer 12b. As a result, a relatively thin layer can be used as the layer covering the interlayer interface of the heat sink 10 in the in-plane direction (x direction in FIG. 5). Furthermore, since the thermal conductivity of Mo is lower than that of Cu, the heat dissipation performance of the heat sink 10 can be enhanced by making the Mo layer 11a thinner than each of the Cu layers 12a and 12b as described above. .

The insulator of the frame 20 is a ceramic insulator. Thereby, the frame 20 has high heat resistance. Therefore, the first bonding material 21 can be formed at a high temperature. Even if a large thermal stress is applied to the heat sink 10 along with this, it is possible to suppress the occurrence of delamination at the interface between the Mo layer 11a and the Cu layer 12a for the reasons described above. In addition, the occurrence of peeling at other similar interfaces can also be suppressed.

The first bonding material 21 is made of brazing material. Accordingly, a high temperature is required to form the first bonding material 21 . Even if a large thermal stress is applied to the heat sink 10 along with this, it is possible to suppress the occurrence of delamination at the interface between the Mo layer 11a and the Cu layer 12a for the reasons described above. In addition, the occurrence of peeling at other similar interfaces can also be suppressed.

The package 50 further includes metal leads 30 for obtaining electrical connection between the inside and outside of the cavity CV and the second bonding material 22 . Even if the heat sink 10 is exposed to temperature changes when the second bonding material 22 is formed, the thermal stress in the heat sink 10 will cause thermal stress between the Mo layer 11a and the Cu layer 12a for the reasons described above. It is possible to suppress the occurrence of peeling at the interface. In addition, the occurrence of peeling at other similar interfaces can also be suppressed.

8: Electronic component 9: Wire 10: Heat sink 10P: Clad material 11a: Mo layer (first layer)
11b: Mo layer (fourth layer)
12a: Cu layer (second layer)
12b: Cu layer (third layer)
12c: Cu layer (fifth layer)
20: Frame 21: First bonding material 22: Second bonding material 30: Metal lead 50: Package 70: Adhesive layer 80: Lid 90: Electronic device CV: Cavity H1: Support surface H1a: Side (second 1 side)
H1b: side H2: bottom H2a: side (second side)
H2b: side (third side)
H2c: Side H3: Side S1: Surface (first surface)
S2: surface (second surface)
S3: surface S4: surface SF1: flat portion (first flat portion)
SF2: flat portion (second flat portion)
SF3: Flat portion SF4: Flat portion SG1: End (first end)
SG2: end (second end)
SG3: Edge SG4: Edge

Claims (10)

A package having a cavity to be sealed by a lid,
a frame made of an insulator and surrounding the cavity in plan view;
a heat sink having a support surface for supporting the frame, a bottom surface opposite to the support surface in a thickness direction perpendicular to the plan view, and a side surface connecting the support surface and the bottom surface;
a first bonding material that bonds the frame and the heat sink to each other;
with
The heat sink
a first layer having first and second surfaces opposite to each other in the thickness direction, forming a first side included in the side surface of the heat sink, and made of a first metal material;
A second metallic material laminated directly to said first surface of said first layer and forming a second side included in said side surface of said heat sink and comprising a second metallic material different from said first metallic material. 2 layers;
A third metal layer laminated directly to the second surface of the first layer and forming a third side included in the side surface of the heat sink and comprising a third metallic material different from the first metallic material. 3 layers;
The first surface of the first layer has, in a cross-sectional view parallel to the thickness direction,
a first flat portion perpendicular to the thickness direction and spaced from the side surface of the heat sink;
a first end angled from the first flat portion to reach the side surface of the heat sink and cut into the second layer. The second surface of the first layer has, in the cross-sectional view,
a second flat portion perpendicular to the thickness direction and spaced from the side surface of the heat sink;
and a second end angled from the second planar portion to reach the side of the heat sink and cut into the third layer. At the side of the heat sink, the first side of the first layer is recessed relative to the second side of the second layer and the third side of the third layer. 3. Package according to claim 1 or 2, having a recessed portion. The concave portion of the first side portion of the first layer is positioned only outside the first flat portion of the first layer in a direction perpendicular to the thickness direction in the cross-sectional view. 4. The package of claim 3, comprising: 5. The package of any one of claims 1-4, wherein the first metallic material is harder than the second metallic material and the third metallic material. 6. A package according to any preceding claim, wherein said second metallic material and said third metallic material are the same. 7. A package according to any preceding claim, wherein the first layer is thinner than each of the second layer and the third layer. 8. The package of any one of claims 1-7, wherein the insulator of the frame is a ceramic insulator. 9. The package according to any one of claims 1 to 8, wherein said first joining material comprises brazing material. metal leads supported by the frame for providing electrical connection between the interior and exterior of the cavity;
a second bonding material that bonds the frame and the metal lead to each other;
10. The package of any one of claims 1-9, further comprising:

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