Heat dissipation substrate, electronic device, and method for manufacturing heat dissipation substrate

Abstract

A heat dissipation plate (11) contains copper and at least one high melting-point metal selected from the group consisting of tungsten and molybdenum, and is made of a sintered body. A first insulating layer (21) has a thickness smaller than the thickness of the heat dissipation plate (11), forms a first bonding surface (SJ1) by being bonded to the heat dissipation plate (11), and is made of ceramic. A conductor layer (31), on which an electronic component (290) is to be mounted: has a thickness smaller than the thickness of the heat dissipation plate (11); forms a second bonding surface (SJ2) by being bonded to the first insulating layer (21); has a mounting surface (SM) which is opposite to the second bonding surface (SJ2) and on which the electronic component (290) is to be mounted; is electrically insulated from the heat dissipation plate (11) by the first insulating layer (21); contains copper and at least one high melting-point metal selected from the group consisting of tungsten and molybdenum; and is made of a sintered body.

Description

Heat dissipation substrate, electronic device, and method for manufacturing heat dissipation substrate

[0001] The present invention relates to a heat dissipation substrate, an electronic device, and a method for manufacturing a heat dissipation substrate.

[0002] Japanese Patent Application Laid-Open Publication No. 2001-135886 (Patent Document 1) discloses a structure including a semiconductor laser chip consisting of a semiconductor substrate and a compound semiconductor layer formed thereon, a base substrate made of CuW (copper-tungsten) to which the semiconductor laser chip is junction-down mounted, a relay portion provided on the chip-mounting surface of the base substrate, and a conductive wire. The relay portion comprises an electrical insulating portion and a conductive portion electrically insulated from the base substrate by the electrical insulating portion. The conductive wire electrically connects the semiconductor substrate and the conductive portion. According to this publication, because CuW has a thermal expansion coefficient very close to that of GaAs, the material used in semiconductor lasers, there is no degradation due to residual stress even when the semiconductor laser chip is mounted junction-down. Furthermore, it is claimed that the conductivity of the CuW base substrate can reduce electrical resistance compared to conventional devices. Specifically, it is claimed that the conductivity of the CuW base substrate itself can reduce Joule loss, which becomes a problem when the drive current increases due to higher output power.

[0003] The publication also states that a coating film made of two layers of Ni / Au plating is formed on the entire surface of the base substrate, and therefore it is believed that the electrical insulating part is directly bonded not to the base substrate made of CuW but to the Au layer of the coating film.

[0004] The semiconductor laser chip is an electronic component (hereinafter also referred to as a heat-generating electronic component) that generates so much heat that heat dissipation from it must be considered. Typical heat-generating electronic components include semiconductor laser elements, LED (Light-Emitting Diode) elements (see, for example, Japanese Patent Laid-Open Publication No. 2006-156447 (Patent Document 2)), and power semiconductor elements. In the structure disclosed in the publication, the heat-generating electronic component is mounted on a base substrate without an electrical insulating portion.

[0005] On the other hand, there are cases where a structure is required in which at least a portion of a heat-generating electronic component is mounted on a base substrate via an insulating layer. For example, the hybrid integrated circuit disclosed in Japanese Patent Laid-Open Publication No. 2005-64168 (Patent Document 3) has such a structure. Specifically, this hybrid integrated circuit includes a heat-generating electronic component (e.g., an IC chip that generates a large amount of heat), other components (e.g., a resistor chip or a capacitor chip), and a metal-based circuit board. In the metal-based circuit board, a circuit is formed on one main surface of a metal plate via an insulating layer. This insulating layer has a region made of a silicone resin with suitable hardness and a region made of a high-thermal-conductivity insulating layer. The other components are mounted on the former region of the insulating layer, and the heat-generating electronic component is mounted on the latter region of the insulating layer, i.e., the high-thermal-conductivity insulating layer. The high-thermal-conductivity insulating layer is an electrically insulating resin layer that may contain an inorganic filler.

[0006] Japanese Patent Laid-Open Publication No. 7-283499 (Patent Document 4) discloses a composite substrate for electronic components, which is manufactured by spraying an insulating ceramic and glass onto a heat sink to form an insulating layer, and then spraying a metal onto the insulating layer to form a conductor layer.

[0007] Japanese Patent Application Laid-Open No. 2001-135886 Japanese Patent Application Laid-Open No. 2006-156447 Japanese Patent Application Laid-Open No. 2005-64168 Japanese Patent Application Laid-Open No. 7-283499

[0008] As described above, the metal-based circuit board (heat dissipation board) disclosed in JP 2005-64168 A has the following drawbacks: First, heat-generating electronic components are mounted on a resin layer serving as a high-thermal-conductivity insulating layer. Generally, resins have a lower thermal conductivity than ceramics. Furthermore, resins have a lower dielectric strength per unit thickness than ceramics. Therefore, heat-generating electronic components are mounted on an insulating layer with a relatively low thermal conductivity and a relatively large thickness. As a result, thermal resistance increases in the heat conduction from the heat-generating electronic components to the metal plate (heat dissipation board). This deteriorates the heat dissipation characteristics of the heat dissipation board. Second, there is a large difference in the linear expansion coefficient between the resin used as the insulating layer and the metal used as the metal plate (heat dissipation board). As a result, delamination between elements of the heat dissipation board is likely to occur under temperature changes. Furthermore, the inclusion of a resin in the insulating layer of the heat dissipation board tends to increase the difference in the linear expansion coefficient between the heat dissipation board and the heat-generating electronic components mounted on the heat dissipation board. As a result, peeling between elements of an electronic device is likely to occur due to temperature changes during the process of mounting heat-generating electronic components on a heat dissipation substrate to manufacture the electronic device, and due to temperature changes in the electronic device after the process, and therefore the reliability of the heat dissipation substrate and the electronic device using it is likely to decrease under temperature changes.

[0009] The composite substrate (heat dissipation substrate) disclosed in JP-A-7-283499 requires a thermal spraying process to form the insulating layer and the conductor layer, and the need for a thermal spraying process is thought to significantly reduce the manufacturing efficiency of the heat dissipation substrate.

[0010] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide technology related to a heat dissipation substrate that can be manufactured with high manufacturing efficiency and has excellent heat dissipation characteristics and high reliability under temperature changes.

[0011] Aspect 1 is a heat dissipation substrate (101-105, 103M, 104M) on which a heat-generating electronic component (290) is mounted. The heat dissipation substrate (101-105, 103M, 104M) comprises a heat dissipation plate (11), a first insulating layer (21), and a conductor layer (31). The heat dissipation plate (11) is for dissipating heat from the electronic component (290), has a first surface (SF1) and a second surface (SF2) opposite the first surface (SF1), contains copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum, and is made of a sintered body. The first insulating layer (21) has a thickness smaller than that of the heat dissipation plate (11), forms a first bonding surface (SJ1) by being bonded to the second surface (SF2) of the heat dissipation plate (11), and is made of ceramic. The conductor layer (31) has a thickness smaller than that of the heat sink (11), forms a second joining surface (SJ2) by being joined to the first insulating layer (21), has a mounted surface (SM) opposite the second joining surface (SJ2) and on which the electronic component (290) is to be mounted, is electrically insulated from the heat sink (11) by the first insulating layer (21), contains copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum, and is made of a sintered body, on which the electronic component (290) is to be mounted.

[0012] Aspect 2 is a heat dissipation substrate (101-105, 103M, 104M) according to aspect 1, wherein the heat dissipation plate (11) and the first insulating layer (21) are sintered together at the first joint surface (SJ1), and the first insulating layer (21) and the conductor layer (31) are sintered together at the second joint surface (SJ2).

[0013] Aspect 3 is a heat dissipation substrate (102, 103) according to aspect 1 or 2, wherein the conductor layer (31) has a side surface (SS) connecting the second joining surface (SJ2) and the mounted surface (SM) to each other, and the heat dissipation substrate (102, 103) further comprises a second insulating layer (22), which extends from the first insulating layer (21) and is joined to the side surface (SS) of the conductor layer (31).

[0014] Aspect 4 is a heat dissipation substrate (103) according to aspect 3, wherein the heat dissipation substrate (103) further comprises a third insulating layer (23), which extends from the second insulating layer (22) and partially covers the mounting surface (SM) of the conductor layer (31).

[0015] Aspect 5 is the heat dissipation substrate (103) according to aspect 4, wherein the first insulating layer (21), the second insulating layer (22), and the third insulating layer (23) are made of a common material.

[0016] Aspect 6 is the heat dissipation substrate (103M) according to Aspect 1 or 2, wherein the conductor layer (31) has an end portion having a thickness that gradually decreases toward the end (ED3) of the conductor layer (31) so that the second bonding surface (SJ2) and the mounted surface (SM) are directly connected to each other at the end (ED3) of the conductor layer (31). The heat dissipation substrate (103M) further includes a third insulating layer (23) extending from the first insulating layer (21) and partially covering the mounted surface (SM) of the conductor layer (31).

[0017] A seventh aspect is the heat dissipation substrate according to the sixth aspect, wherein the first insulating layer (21) and the third insulating layer (23) are made of a common material.

[0018] Aspect 8 is the heat dissipation substrate (105) according to Aspect 1 or 2, wherein the heat dissipation plate (11) has a via hole (VH) connecting the first surface (SF1) and the second surface (SF2) to each other, and the heat dissipation substrate (105) further includes an inner wall insulating layer (29) and a via electrode (39). The inner wall insulating layer (29) extends from the first insulating layer (21) and covers the inner wall (SW) of the via hole (VH). The via electrode (39) extends from the conductor layer (31), penetrates the via hole (VH) of the heat dissipation plate (11), and is insulated from the heat dissipation plate (11) by the inner wall insulating layer (29).

[0019] Aspect 9 is a heat dissipation substrate (101-105) according to any one of Aspects 1 to 8, wherein in a cross-sectional view of at least a portion of the first bonding surface (SJ1), the first bonding surface (SJ1) extends macroscopically along a straight line and microscopically forms a first boundary line having undulations between the heat dissipation plate (11) and the first insulating layer (21), the first boundary line having a copper section made of copper and a high-melting-point metal section made of the at least one high-melting-point metal, and the length proportion occupied by the high-melting-point metal section in the projection of the first boundary line onto the straight line is greater than the area proportion occupied by the at least one high-melting-point metal in the heat dissipation plate (11) in a cross-sectional view of at least a portion of the first bonding surface (SJ1).

[0020] Aspect 10 is a heat dissipation substrate (101-105) described in any one of Aspects 1 to 9, wherein, in a cross-sectional view of at least a portion of the second bonding surface (SJ2), the second bonding surface (SJ2) extends macroscopically along a straight line and microscopically forms a second boundary line having undulations between the first insulating layer (21) and the conductor layer (31), the second boundary line having a copper section made of copper and a high-melting-point metal section made of the at least one high-melting-point metal, and the length proportion occupied by the high-melting-point metal section in the projection of the second boundary line onto the straight line is greater than the area proportion occupied by the at least one high-melting-point metal in the conductor layer (31) in a cross-sectional view of at least a portion of the second bonding surface.

[0021] Aspect 11 is the heat dissipation substrate (104) according to any one of aspects 1 to 10, further comprising an internal electrode (40, 40M) embedded in the first insulating layer (21) and connected to the conductor layer (31).

[0022] Aspect 12 is a heat dissipation substrate according to aspect 11, wherein the internal electrode (40) includes an inner layer portion (41) extending in an in-plane direction away from both main surfaces of the first insulating layer (21), and a via portion (42) connecting the inner layer portion (41) and the conductor layer (31).

[0023] Aspect 13 is a heat dissipation substrate according to aspect 11, wherein the first insulating layer (21) includes a first film (21a) having a portion separating the heat dissipation plate (11) and the internal electrode (40M) in the thickness direction, and a second film (21b) having a portion separating the internal electrode (40M) and the conductor layer (31) in the thickness direction and a hole (HL) between the internal electrode (40M) and the conductor layer (31), and the second film (21b) has a thickness that gradually decreases toward the hole (HL) so that the internal electrode (40M) and the conductor layer (31) are directly connected to each other at the hole (HL).

[0024] Aspect 14 is an electronic device (201) comprising a heat dissipation substrate (101-105) according to any one of aspects 1 to 11, and the electronic component (290) mounted on the conductor layer (31).

[0025] Aspect 15 is the electronic device (201) according to aspect 14, wherein the electronic component (290) includes a power semiconductor element.

[0026] Aspect 16 is the electronic device (201) according to aspect 14 or 15, wherein the electronic component (290) includes a semiconductor light-emitting element.

[0027] Aspect 17 is a method for manufacturing a heat dissipation substrate (101-105) for manufacturing the heat dissipation substrate (101-105) according to any one of Aspects 1 to 13, comprising the steps of forming a green laminate (G101-G105) and firing the green laminate (G101-G105). The green laminate (G101-G105) includes a green heat dissipation plate (G11) that becomes the heat dissipation plate (11) when fired, a green insulating layer (G21) that becomes the first insulating layer (21) when fired, and a green conductor layer (G31) that becomes the conductor layer (31) when fired.

[0028] According to aspect 1, first, the heat sink (11) has high thermal conductivity due to the inclusion of copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum. Furthermore, the conductor layer (31) has high thermal conductivity due to the inclusion of copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum. Furthermore, the first insulating layer (21) is made of ceramic, which facilitates ensuring high thermal conductivity and high withstand voltage per unit thickness. This allows the first insulating layer (21) to be a thin layer made of a material with high thermal conductivity. As a result, the thermal resistance due to the first insulating layer (31) in the heat conduction from the conductor layer (31) to the heat sink (11) can be reduced. This allows the heat dissipation substrate (101-105) to achieve excellent heat dissipation characteristics. Secondly, since the first insulating layer (21) of the heat dissipation substrate (101-105, 103M, 104M) is made of ceramic, it is easy to reduce the difference in the linear expansion coefficient between the first insulating layer (21) and each of the heat dissipation plate (11) and the conductor layer (31), and as a result, it is possible to make it difficult for peeling to occur between the elements of the heat dissipation substrate (101-105, 103M, 104M) under temperature changes. Furthermore, by using ceramic for the first insulating layer (31) of the heat dissipation substrate (101-105, 103M, 104M), the difference in the linear expansion coefficient between the heat dissipation substrate (101-105) and the electronic component (290) mounted thereon can be easily reduced. As a result, peeling between elements of the electronic device (201) is less likely to occur during temperature changes in the process of mounting the electronic component (290) on the heat dissipation substrate (101-105, 103M, 104M) to manufacture the electronic device (201), and during temperature changes in the electronic device (201) after the process. This improves the reliability of the heat dissipation substrate (101-105, 103M, 104M) and the electronic device (201) using the same under temperature changes. Third, the heat dissipation plate (11) is made of a sintered body, and the conductor layer (31) is also made of a sintered body. This allows the heat dissipation plate (11) and the conductor layer (31) to be easily formed using a firing process. Therefore, the manufacturing efficiency of the heat dissipation substrates (101 to 105) can be improved.From the above, it is possible to obtain a heat dissipation substrate (101 to 105, 103M, 104M) that can be manufactured with high manufacturing efficiency and has excellent heat dissipation characteristics and high reliability under temperature changes.

[0029] According to Aspect 2, the heat sink (11) and the first insulating layer (21) are sintered to each other at the first joint surface (SJ1), and the first insulating layer (21) and the conductor layer (31) are sintered to each other at the second joint surface (SJ2). This strengthens the bond between the heat sink (11) and the first insulating layer (21) and the bond between the first insulating layer (21) and the conductor layer (31). This makes it less likely that peeling will occur between the heat sink (11) and the first insulating layer (21) and between the first insulating layer (21) and the conductor layer (31) due to thermal stress. This further improves reliability under temperature changes.

[0030] According to Aspect 3, a second insulating layer (22) extending from the first insulating layer (21) is bonded to the side surface (SS) of the conductor layer (31). This allows the conductor layer (31) to be fixed not only by the first insulating layer (21) but also by the second insulating layer (22). This makes the conductor layer (31) less likely to peel off. Furthermore, according to Aspect 4, a third insulating layer (23) extending from the second insulating layer (22) partially covers the mounting surface (SM) of the conductor layer (31). This allows the conductor layer (31) to be fixed not only by the first insulating layer (21) and the second insulating layer (22) but also by the third insulating layer (23). This makes the conductor layer (31) even less likely to peel off. Furthermore, according to Aspect 5, the first insulating layer (21), the second insulating layer (22), and the third insulating layer (23) are made of a common material. This prevents peeling between these layers.

[0031] According to Aspect 6, the third insulating layer (23) extending from the first insulating layer (21) partially covers the mounting surface (SM) of the conductor layer (31). This allows the conductor layer (31) to be fixed not only by the first insulating layer (21) but also by the third insulating layer (23). This makes the conductor layer (31) less likely to peel off. Furthermore, according to Aspect 7, the first insulating layer (21) and the third insulating layer (23) are made of the same material. This prevents peeling between these layers.

[0032] According to the eighth aspect, an electrical path can be provided to the heat dissipation substrate (105) by the via electrode (39), connecting the first surface (SF1) and the second surface (SF2).

[0033] According to Aspect 9, in a cross-sectional view of at least a portion of the first joint surface (SJ1), the length ratio of the high-melting-point metal section in the projection of the first boundary line onto a straight line along which the first joint surface (SJ1) extends macroscopically is greater than the area ratio of the at least one high-melting-point metal in the heat sink (11). This large ratio allows the thermal expansion coefficient of the portion of the heat sink (11) facing the first insulating layer (21) in the linear direction to be closer to the thermal expansion coefficient of the first insulating layer (21). This prevents the heat sink (11) and the first insulating layer from peeling off from each other.

[0034] According to Aspect 10, in a cross-sectional view of at least a portion of the second joint surface (SJ2), the length ratio of the high-melting-point metal section in the projection of the second boundary line onto a straight line along which the second joint surface (SJ2) extends macroscopically is greater than the area ratio of the at least one high-melting-point metal in the conductor layer (31). This large ratio allows the thermal expansion coefficient of the portion of the conductor layer (31) facing the first insulating layer (21) in the linear direction to approach the thermal expansion coefficient of the first insulating layer (21). This prevents the conductor layer (31) and the first insulating layer (21) from peeling off from each other.

[0035] According to the eleventh aspect, the internal electrodes (40) together with the conductor layers (31) constitute wiring, so that the heat dissipation substrate (104) can have more complex wiring.

[0036] According to the fourteenth aspect, for the same reasons as those explained in the first aspect, it is possible to obtain an electronic device (201) having excellent heat dissipation characteristics and high reliability under temperature changes.

[0037] According to the fifteenth aspect, the electronic component (290) in the electronic device (201) is a power semiconductor element, which tends to generate a large amount of heat. In such a case, the effect described in the ninth aspect is more pronounced.

[0038] According to the sixteenth aspect, the electronic component (290) in the electronic device (201) is a semiconductor light-emitting element, which tends to generate a large amount of heat. In such a case, the effect described in the eighth aspect is more pronounced.

[0039] According to the seventeenth aspect, the heat sink (11), the first insulating layer (21), and the conductor layer (31) are formed by simultaneous firing, thereby increasing the bonding strength therebetween.

[0040] The symbols in parentheses in the above-mentioned embodiments are merely supplementary to help understand the contents of the above-mentioned embodiments, and do not limit the above-mentioned embodiments.

[0041] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

[0042] FIG. 1 is a cross-sectional view schematically showing the configuration of an electronic device according to a first embodiment. FIG. 2 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing a step of a method for manufacturing the heat dissipation substrate of FIG. 2. FIG. 4 is an electron microscope photograph showing the vicinity of a first bonding surface between a heat dissipation plate and a first insulating layer and a second bonding surface between the first insulating layer and a conductor layer. FIG. 5 is an electron microscope photograph showing the vicinity of the second bonding surface between the first insulating layer and the conductor layer. FIG. 6 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate of a first comparative example. FIG. 7 is a cross-sectional view schematically showing a first step of a method for manufacturing the heat dissipation substrate of FIG. 6. FIG. 8 is a cross-sectional view schematically showing a second step of a method for manufacturing the heat dissipation substrate of FIG. 6. FIG. 9 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate according to a second embodiment. FIG. 10 is a cross-sectional view schematically showing a step of a method for manufacturing the heat dissipation substrate of FIG. 9. FIG. 11 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate according to a third embodiment. FIG. 12 is a cross-sectional view schematically showing a step of a method for manufacturing the heat dissipation substrate of FIG. 11. Fig. 13 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate of a modified example of Fig. 11. Fig. 14 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate according to embodiment 4. Fig. 15 is a cross-sectional view schematically showing one step of a method for manufacturing the heat dissipation substrate of Fig. 14. Fig. 16 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate of a modified example of Fig. 14. Fig. 17 is a cross-sectional view schematically showing the configuration of a heat dissipation substrate according to embodiment 5. Fig. 18 is a cross-sectional view schematically showing one step of a method for manufacturing the heat dissipation substrate of Fig. 17. Fig. 19 is a cross-sectional view showing the configuration of a heat dissipation substrate of a second comparative example.

[0043] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification, unless otherwise specified, the term "metal" can refer to either a pure metal or an alloy. The term "alloy" can refer to a solid solution of multiple metal components, a mixture of multiple metals that has not been solidified, or an intermetallic compound. The term "green" refers to the state before firing. Therefore, a component labeled "green" is to be fired, but has not yet been fired. The terms "upper" and "lower" are used to distinguish relative directions and do not imply limitations related to the direction of gravity, unless otherwise specified.

[0044] 1 and 2 are cross-sectional views each showing a schematic configuration of an electronic device 201 and a heat dissipation substrate 101 according to a first embodiment. The heat dissipation substrate 101 includes a heat sink 11, a first insulating layer 21, and a conductor layer 31. An electronic component 290 ( FIG. 1 ) is mounted on the conductor layer 31 of the heat dissipation substrate 101 ( FIG. 2 ) using a bonding material 291 such as solder. Note that in addition to the electronic component 290 ( FIG. 1 ), other components (not shown) may also be mounted on the heat dissipation substrate 101 ( FIG. 2 ). The electronic component 290 is an electronic component that generates heat during operation, specifically, the heat-generating electronic component described above. The electronic component 290 may include a power semiconductor element. The electronic component 290 may also include a semiconductor light-emitting element. The semiconductor light-emitting element may be an LED element, in which case the electronic device 201 is an LED module.

[0045] The heat sink 11 is for dissipating heat from the electronic component 290. The heat sink 11 may have a thickness sufficient to ensure the mechanical strength of the heat sink 11 as a freestanding substrate. The thickness of the heat sink 11 is preferably 0.3 mm or more and 3.0 mm or less, and more preferably 0.5 mm or more and 1.5 mm or less. If the thickness is too small, the mechanical strength of the heat sink 11 will be insufficient. If the thickness is too large, the thermal resistance will be excessively high. The heat sink 11 has a first surface SF1 and a second surface SF2 opposite to the first surface SF1.

[0046] The heat sink 11 contains copper (Cu) and at least one high-melting-point metal selected from the group consisting of tungsten (W) and molybdenum (Mo). The heat sink 11 is made of a sintered body. In the sintered body, the Cu portion may be a portion that solidifies after melting during the firing process for manufacturing the heat sink substrate 101 due to its low melting point, and may extend to connect the crystal grains of the high-melting-point metal. If the total volume of the metal components of the heat sink 11 is defined as 100 vol%, the heat sink 11 may contain 10 vol% to 90 vol% Cu, with the remainder being essentially the high-melting-point metal. As described above, the high-melting-point metal is W, Mo, or both W and Mo.

[0047] If the total volume of the heat sink 11 is defined as 100 vol%, the heat sink 11 may contain 30 vol% or less of ceramic. This ceramic is, for example, alumina. Other ceramics may be contained together with or instead of alumina, such as SiO ２ and / or MnO ２ The heat sink 11 may contain ceramic. By including ceramic in the heat sink 11, the adhesion between the heat sink 11 and the first insulating layer 21 is improved. The ceramic may also contain silicon oxide particles with an average particle size of 5 nm to 200 nm. The particles have the effect of lowering the Young's modulus of the heat sink 11.

[0048] The first insulating layer 21 has a thickness smaller than that of the heat sink 11. The thickness of the first insulating layer 21 is preferably 5 μm or more and 50 μm or less, and more preferably 5 μm or more and 20 μm or less. If the thickness is too small, variations in the thickness of the first insulating layer 21 are likely to become a problem. Specifically, electrical insulation is likely to be insufficient in areas where the thickness is locally small. If the thickness is too large, thermal resistance will be excessively high. The first insulating layer 21 is bonded to the second surface SF2 of the heat sink 11 to form a first bonding surface SJ1. The first bonding surface SJ1 is approximately perpendicular to the thickness direction (the vertical direction in FIG. 2 ). Note that the entire bonding surface between the first insulating layer 21 and the heat sink 11 may be approximately perpendicular to the thickness direction.

[0049] The heat sink 11 and the first insulating layer 21 are sintered to each other at the first bonding surface SJ1. That is, the heat sink 11 and the first insulating layer 21 are bonded to each other by sintering at the first bonding surface SJ1. Such a first bonding surface SJ1 is obtained by forming the heat sink 11 and the first insulating layer 21 by co-firing.

[0050] The first insulating layer 21 is made of ceramic. The ceramic contains alumina (Al ２ O ３ ), and may further contain glass components. For example, a trace amount of silica (SiO ２The first insulating layer 21 may contain, for example, 50 wt % or more of Al as a main component, and may also contain an additive containing Mn element. ２ O ３ powder and SiO ２ The powder may be a mixture of a Si-containing powder equivalent to 5 to 17 wt % in terms of SiO and a Mn-containing powder equivalent to 3 to 14 wt % in terms of MnO. When the mixture is used, the firing temperature is, for example, 1150 to 1300° C. The firing time is, for example, 1 to 50 hours.

[0051] The conductor layer 31 has a thickness smaller than that of the heat sink 11. The thickness of the conductor layer 31 is preferably 5 μm or more and 200 μm or less, and more preferably 5 μm or more and 20 μm or less. If the thickness is too small, variations in the thickness of the conductor layer 31 are likely to become a problem. If the thickness is too large, the number of printing operations increases, reducing productivity. The conductor layer 31 is bonded to the first insulating layer 21 to form a second bonding surface SJ2. The second bonding surface SJ2 is approximately perpendicular to the thickness direction (the vertical direction in FIG. 2 ). Note that the entire bonding surface between the conductor layer 31 and the first insulating layer 21 may be approximately perpendicular to the thickness direction. The first insulating layer 21 and the conductor layer 31 are sintered to each other at the second bonding surface SJ2. That is, the first insulating layer 21 and the conductor layer 31 are bonded to each other by sintering at the second bonding surface SJ2. The second bonding surface SJ2 is obtained by co-firing the first insulating layer 21 and the conductor layer 31. The conductor layer 31 has a mounting surface SM opposite the second bonding surface SJ2, on which the electronic component 290 is mounted. Wire bonding or the like may be bonded to the conductor layer 31. The conductor layer 31 also has a side surface SS connecting the second bonding surface SJ2 and the mounting surface SM. As described in a modified example of the third embodiment below, the conductor layer 31 in the first embodiment may also be modified so as not to have the side surface SS. The conductor layer 31 is electrically insulated from the heat sink 11 by the first insulating layer 21.

[0052] The conductor layer 31 contains Cu and at least one high-melting-point metal selected from the group consisting of W and Mo. The conductor layer 31 is made of a sintered body. In the sintered body, the Cu portion may be a portion that solidified after melting during the firing process for manufacturing the heat dissipation substrate 101 due to its low melting point, and may extend to bond between the crystal grains of the high-melting-point metal. If the total volume of the metal components of the conductor layer 31 is defined as 100 vol%, the conductor layer 31 may contain 10 vol% to 90 vol% Cu, with the remainder being essentially the high-melting-point metal. As described above, the high-melting-point metal is W, Mo, or both W and Mo.

[0053] If the total volume of the conductor layer 31 is defined as 100 vol%, the conductor layer 31 may contain 30 vol% or less of ceramic. This ceramic is, for example, alumina. Other ceramics, such as glass components, may be contained together with or instead of alumina. For example, SiO ２ and / or MnO ２ The conductor layer 31 may contain a ceramic. When the conductor layer 31 contains ceramic, the adhesion between the conductor layer 31 and the first insulating layer 21 is improved. The ceramic may also contain silicon oxide particles with an average particle size of 5 nm or more and 200 nm or less. These particles have the effect of suppressing the migration of Cu in the conductor layer 31 during the firing process for manufacturing the heat dissipation substrate 101. The material of the conductor layer 31 may be the same as the material of the heat dissipation plate 11 described above. However, for some reason, these materials may be different from each other.

[0054] When the ceramic of the first insulating layer 21 contains Mn as described above, a Mn concentration profile can be obtained by elemental analysis in the depth direction. The Mn concentration profile can be measured, for example, by scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX). Here, the first insulating layer 21 is considered to be composed of a first surface layer portion within a depth range of 3 μm from the first bonding surface SJ1 into the first insulating layer 21, a second surface layer portion within a depth range of 3 μm from the second bonding surface SJ2 into the first insulating layer 21, and a bulk portion located between the first and second surface layer portions.

[0055] The maximum peak of the Mn concentration profile in the first surface layer portion and the bulk portion may be located within the first surface layer portion. The maximum peak may be 150% or more of the representative value of the Mn concentration profile in the bulk portion. Furthermore, the maximum peak of the Mn concentration profile in the second surface layer portion and the bulk portion may be located within the second surface layer portion. The maximum peak may be 150% or more of the representative value of the Mn concentration profile in the bulk portion. It is believed that the percentage of each of the above maximum peaks can be increased, for example, to about 1000%, by adjusting various conditions. The representative value of the bulk portion may be, for example, the peak value in the bulk portion.

[0056] The inventors' investigations suggest that it is possible to increase the bonding strength of the first bonding surface SJ1 by locally increasing the Mn concentration in the first surface layer portion of the first insulating layer 21. Although the mechanism behind this has not yet been verified, it is thought that this may be due to bonding between Mn atoms in the first insulating layer 21 and metal atoms in the heat sink 11. Similarly, it is thought that it is possible to increase the bonding strength of the second bonding surface SJ2 by ​​locally increasing the Mn concentration in the second surface layer portion of the first insulating layer 21.

[0057] 3 is a cross-sectional view schematically showing one step in the manufacturing method of the heat dissipation substrate 101. First, a green laminate G101 is formed. The green laminate G101 includes a green heat dissipation plate G11 that becomes the heat dissipation plate 11 when fired, a green insulating layer G21 that becomes the first insulating layer 21 when fired, and a green conductor layer G31 that becomes the conductor layer 31 when fired. The heat dissipation substrate 101 is obtained when the green laminate G101 is fired.

[0058] In the green laminate G101, the green insulating layer G21 forms a first contact surface GSJ1 by contacting the second surface SF2 of the green heat sink G11. The first contact surface GSJ1 is approximately perpendicular to the thickness direction, in other words, the stacking direction (the vertical direction in FIG. 3). The first contact surface GSJ1 is the surface that becomes the first bonding surface SJ1 (FIG. 2) after firing. It is preferable that a press pressure be applied to the green heat sink G11 and the green insulating layer G21 so that they are pressed against each other at the first contact surface GSJ1. Because the first contact surface GSJ1 is perpendicular to the stacking direction, a press pressure along the stacking direction is effectively applied to the first contact surface GSJ1. The pressure at the bonding surface at this time is 10 to 150 kgf / cm ２ By setting the pressure within this range, it is possible to obtain sufficient bonding strength after firing while suppressing deformation and displacement of the green laminate G101.

[0059] In the green laminate G101, the green conductor layer G31 forms a second contact surface GSJ2 by ​​contacting the green insulating layer G21. The second contact surface GSJ2 is approximately perpendicular to the thickness direction, in other words, the stacking direction (the vertical direction in FIG. 3). The second contact surface GSJ2 is a surface that becomes the second joining surface SJ2 (FIG. 2) after firing. It is preferable that a press pressure be applied to the green insulating layer G21 and the green conductor layer G31 so that they are pressed against each other at the second contact surface GSJ2. Because the second contact surface GSJ2 is perpendicular to the stacking direction, a press pressure along the stacking direction is effectively applied to the second contact surface GSJ2. The pressure at the joining surface at this time is 10 to 150 kgf / cm. ２ By setting the pressure within this range, it is possible to obtain sufficient bonding strength after firing while suppressing deformation and displacement of the green laminate G101.

[0060] To explain the manufacturing method more specifically, in a first example, a green sheet is formed as a green heat sink G11. Next, a green insulating layer G21 is formed on the green heat sink G11 by printing (e.g., screen printing). Next, a green conductor layer G31 is formed on the green insulating layer G21 by printing. This method is particularly suitable when the thickness of the conductor layer G31 is 50 μm or less.

[0061] In the first example, the above-described pressing pressures are applied by printing pressure. If it is necessary to apply a larger pressing pressure, a pressing process along the thickness direction may be performed on the green laminate G101 (or a green laminate in each embodiment described below that has a similar structure) separately from the printing process.

[0062] In a second example, a green sheet is formed as the green heat sink G11. Next, a green insulating layer G21 is formed on the green heat sink G11 by printing. Meanwhile, a green sheet is formed as the green conductor layer G31. Next, a green sheet as the green conductor layer G31 is laminated on the green insulating layer G21. This method is particularly suitable when the thickness of the conductor layer 31 is 50 μm or more.

[0063] In the second example, the step of laminating the green sheets as the green conductor layer G31 also serves to apply the aforementioned pressing pressures. If it is necessary to apply a larger pressing pressure, a pressing process along the thickness direction may be additionally performed after the lamination step of the green conductor layer G31.

[0064] To form the green sheet as described above, a slurry is first prepared. The slurry is obtained by mixing powders that will become the components of the sintered body with resin, plasticizer, solvent, etc. using a ball mill. A green sheet is then formed from this slurry using, for example, a doctor blade method.

[0065] 4 is an electron microscope photograph showing the vicinity of the first bonding surface SJ1 between the heat sink 11 and the first insulating layer 21 and the second bonding surface SJ2 between the first insulating layer 21 and the conductor layer 31. In the example shown in this photograph, the first insulating layer 21 contained alumina as a main component and silicon oxide and manganese oxide as additives. The thickness of the first insulating layer 21 was 10 μm, the thickness of the conductor layer 31 was 12 μm, and the thickness of the heat sink 11 was 1 mm.

[0066] The conductor layer 31 contained 9.8 vol% of a ceramic component (ceramic portion 31R, which is the black portion in the conductor layer 31 in FIG. 4 ) and 90.2 vol% of a metal component, assuming that the total volume of the conductor layer 31 is 100 vol%. The metal component was made of a CuW material, and in the example of FIG. 4 , the metal component contained 40 vol% of Cu (Cu portion 31C, which is the gray portion in the conductor layer 31 in FIG. 4 ) and 60 vol% of W (W portion 31W, which is the white portion in the conductor layer 31 in FIG. 4 ), assuming that the total volume of the metal component is 100 vol%. In this photograph, there is a sufficient difference in contrast between the ceramic portion 31R, the Cu portion 31C, and the W portion 31W, so that the amounts of Cu and W can be analyzed with sufficient accuracy. Specifically, image processing is performed to classify the conductor layer 31 in the electron microscope photograph into three regions based on contrast, allowing the ceramic portion 31R, the Cu portion 31C, and the W portion 31W to be distinguished. The heat sink 11 has a Cu portion 11C and a W portion 11W, and these portions can be easily distinguished as well. Image processing may be performed using image processing software. For example, "ImageJ" may be used as the image processing software.

[0067] In the above electron microscope photograph, which shows a cross-section of at least a portion of the second bonding surface SJ2, the second bonding surface SJ2 extends along a straight line macroscopically, while microscopically forming an undulating second boundary line between the first insulating layer 21 and the conductor layer 31. Here, the macroscopic straight line may be obtained by linear approximation of a microscopic boundary line in a dimension range of several tens of micrometers to 100 micrometers. In this photograph, the macroscopic straight line may be obtained by linear approximation of a boundary line having undulations in a range of 30 micrometers in the X direction. Note that in FIG. 4 , for ease of viewing, the approximate line of the second bonding surface SJ2 is shown slightly shifted toward the first insulating layer 21. Furthermore, the above-mentioned undulations can be easily observed by cross-sectional observation using a scanning electron microscope with normal resolution. For example, a cross-sectional view in which the undulations are clearly discernible, as in this photograph, can be sufficiently observed if a resolution of, for example, about 0.1 micrometers (or less) is ensured.

[0068] The second boundary line includes a copper section made of Cu and a high-melting-point metal section made of W (more generally, at least one high-melting-point metal) on the surface of the conductor layer 31 facing the first insulating layer 21 (on the underside of the conductor layer 31 in FIG. 4 ). By projecting the high-melting-point metal section and the copper section on the second boundary line onto the macroscopic straight line (see "Cu" and "W" in FIG. 4 ), the proportions of W and Cu on the second boundary line can be easily calculated. In the example of FIG. 4 , the length ratio of Cu to W on the straight line was 12.4:87.6. Meanwhile, in the field of view including the cross-sectional view of FIG. 4 , the area ratio of Cu to W on the conductor layer 31 was 40:60. Therefore, the length ratio of W was 1.46 times the area ratio. The magnification may be 1.1 times or more, preferably 1.3 times or more, and more preferably 1.4 times or more. The magnification may be 3 times or less.

[0069] The volume fractions of W and Cu in the conductor layer 31 can be estimated based on the area fractions of W and Cu in the conductor layer 31 in the electron microscope photograph. In the electron microscope photograph, the region of the conductor layer 31 used to calculate the area fractions may be, for example, approximately 5 μm or more in thickness and approximately 20 μm to 40 μm in width. By having a thickness of approximately 5 μm or more, the influence of compositional deviation in the thickness direction on the calculation results can be largely ignored. By having a width of approximately 20 μm or more, the accuracy of the calculation value can be sufficiently ensured.

[0070] As described above, the condition that the length ratio is greater than the area ratio corresponding to the volume ratio is satisfied. Here, since the length ratio corresponds to the area ratio at the second bonding surface SJ2 (not the area ratio in the cross-sectional view), satisfying this condition means that the area ratio of W at the second bonding surface SJ2 of the conductor layer 31 is greater than the volume ratio of W at the conductor layer 31. This means that the W portion in the conductor layer 31 is more unevenly distributed at the second bonding surface SJ2. The inventors believe that the degree of this uneven distribution is also related to the manufacturing method. Specifically, the inventors believe that applying the aforementioned press pressure to the second contact surface GSJ2 ( FIG. 3 ), where a pair of green members (specifically, the green conductor layer G31 and the green insulating layer G21) contact each other, may contribute to improving this ratio. Furthermore, the inventors believe that the proportion of the high-melting-point metal section may be increased by increasing the firing temperature and firing time.

[0071] The characteristics of the composition distribution in the vicinity of the second bonding surface SJ2 have been described in detail above, but the characteristics of the composition distribution in the vicinity of the first bonding surface SJ1 are similar to these. This will be specifically described below.

[0072] Heat sink 11 contained 100 vol% of a metal component, assuming that the total volume of heat sink 11 is 100 vol%. The metal component was made of CuW material, and in the example of Figure 4, if the total volume of the metal component was 100 vol%, it contained 30 vol% of Cu (Cu portion 11C, which is the gray portion of heat sink 11 in Figure 4) and 70 vol% of W (W portion 11W, which is the white portion of heat sink 11 in Figure 4). In this photograph, as mentioned above, there is a sufficient difference in contrast between Cu portion 11C and W portion 11W, so the amounts of Cu and W can be analyzed with sufficient accuracy.

[0073] In the above electron microscope photograph, which is a cross-sectional view of at least a portion of the first bonding surface SJ1, the first bonding surface SJ1 extends along a straight line macroscopically, and microscopically forms an undulating first boundary line between the first insulating layer 21 and the heat sink 11. Here, the macroscopic straight line may be obtained by linear approximation of a microscopic boundary line in a dimensional range of several tens of microns to 100 microns. In this photograph, it may be obtained by linear approximation of an undulating boundary line in a range of 30 microns in the X direction. Note that in FIG. 4 , for ease of viewing, the approximation line of the first bonding surface SJ1 is shown slightly shifted toward the first insulating layer 21. Furthermore, the above-mentioned undulations can be easily observed by cross-sectional observation using a scanning electron microscope with normal resolution. For example, a cross-sectional view in which the undulations can be clearly distinguished, as in this photograph, can be sufficiently observed if a resolution of, for example, about 0.1 microns (or less) is ensured.

[0074] The first boundary line includes a copper section made of Cu and a high-melting-point metal section made of W (more generally, at least one high-melting-point metal) on the surface of the heat sink 11 facing the first insulating layer 21 (on the top surface of the heat sink 11 in FIG. 4 ). By projecting each of the high-melting-point metal section and the copper section on the first boundary line onto the macroscopic straight line (see "Cu" and "W" in FIG. 4 ), the proportions of W and Cu on the first boundary line can be easily calculated. In the example of FIG. 4 , the length ratio of Cu to W on the straight line was found to be 7.3:92.7. Meanwhile, in the field of view including the cross-sectional view of FIG. 4 , the area ratio of Cu to W on the heat sink 11 was found to be 30:70. Therefore, the length ratio of W was 1.32 times the area ratio. The magnification may be 1.1 times or more, preferably 1.3 times or more, and more preferably 1.4 times or more. The magnification may be 3 times or less.

[0075] The volume fractions of W and Cu in the heat sink 11 can be estimated based on the area fractions of W and Cu in the heat sink 11 in the electron microscope photograph. In the electron microscope photograph, the region of the heat sink 11 used to calculate the area fractions may be, for example, approximately 50 μm or more in thickness and approximately 20 μm to 40 μm in width. By having a thickness of approximately 50 μm or more, the influence of compositional deviations in the thickness direction on the calculation results can be largely ignored. By having a width of approximately 20 μm or more, the accuracy of the calculation value can be sufficiently ensured.

[0076] As described above, the condition that the length ratio is greater than the area ratio corresponding to the volume ratio is satisfied. Here, since the length ratio corresponds to the area ratio at the first bonding surface SJ1 (not the area ratio in the cross-sectional view), satisfying this condition means that the area ratio of W at the first bonding surface SJ1 of the heat sink 11 is greater than the volume ratio of W at the heat sink 11. This means that the W portion in the heat sink 11 is more unevenly distributed at the first bonding surface SJ1. The inventors believe that the degree of this uneven distribution is also related to the manufacturing method. Specifically, the inventors believe that applying the aforementioned press pressure to the first contact surface GSJ1 ( FIG. 3 ), where a pair of green members (specifically, the green heat sink G11 and the green insulating layer G21) contact each other, may contribute to improving this ratio. Furthermore, the inventors believe that the proportion of the high-melting-point metal section may be increased by increasing the firing temperature and firing time.

[0077] FIG. 5 is an electron microscope photograph showing the vicinity of the second bonding surface SJ2 between the first insulating layer 21 and the conductor layer 31 in an example different from the example in FIG. 4 . In the example shown in this photograph, the first insulating layer 21 contains alumina as a primary component and silicon oxide and manganese oxide as additives. The conductor layer 31 contains 10 vol% of a ceramic component (the black portion of the conductor layer 31 in FIG. 5 ) and 90 vol% of a metal component, assuming the total volume of the conductor layer 31 to be 100 vol%. The metal component is made of a CuW material, and specifically, contains 50 vol% of Cu (the gray portion of the conductor layer 31 in FIG. 5 ) and 50 vol% of W (the white portion of the conductor layer 31 in FIG. 5 ) when the total volume of the metal component is 100 vol%.

[0078] The length ratio and area ratio described above may also be calculated for the second bonding surface SJ2 in the electron microscope photograph of Fig. 5. In the photograph of Fig. 5, the linear approximation described above when calculating the length ratio may be performed on a boundary line having undulations in a range of 20 μm to 40 μm in the X direction. Furthermore, the region of the conductor layer 31 used to calculate the area ratio may have a thickness of approximately 5 μm or more and a width of approximately 20 μm to 40 μm, for example.

[0079] 6 is a cross-sectional view showing the configuration of a heat dissipation substrate 191 of the first comparative example. The heat dissipation substrate 191 has a heat dissipation plate 11Z, a first insulating layer 21Z, and a conductor layer 31Z in an arrangement similar to that of the heat dissipation plate 11, the first insulating layer 21, and the conductor layer 31 of the first embodiment. A method for manufacturing the heat dissipation substrate 191 will be described below.

[0080] 7, first, a heat sink 11Z made of CuW material is formed. Then, as shown in FIG. 8, a SiO ２ A first insulating layer 21Z made of Au is formed on the heat sink 11Z. The formation method is by vapor deposition or paste application on the heat sink 11Z. Referring again to FIG. 6, a conductor layer 31Z made of Au is formed on the first insulating layer 21Z. The formation method is by vapor deposition or paste application on the first insulating layer 21Z.

[0081] As described above, layers formed by vapor deposition or paste application generally tend to have poor adhesion. Furthermore, in the heat dissipation substrate 191, the heat dissipation plate 11Z is made of CuW material and the conductor layer 31Z is made of Au, so there is a large difference in the linear expansion coefficient between the two. This can cause delamination. Furthermore, the use of Au increases raw material costs.

[0082] If CuW were used instead of Au as the material for the conductor layer 31Z formed by vapor deposition or paste application as described above, the following problems would be considered. First, it would be considered difficult, at least industrially, to form a layer made of CuW by vapor deposition. Second, if a layer made of CuW is formed by forming a paste layer and firing the paste layer, unnecessary heating of the heat sink 11Z during the firing process would cause Cu to evaporate from the CuW material of the heat sink 11Z, resulting in unintended variations in the composition of the heat sink 11Z ( FIG. 7 ).

[0083] Furthermore, the heat sink 11Z ( FIG. 7 ) made of CuW material is typically formed through a process in which W particles and molten Cu coexist at high temperatures exceeding the melting point of Cu. It is well known that molten Cu has high wettability with solid W. From the perspective of wettability, the second surface SF2 of the heat sink 11Z is likely to be Cu-rich compared to the average Cu content of the heat sink 11Z due to the spread of Cu. Therefore, the first bonding surface SJ1 of the heat sink 191 ( FIG. 6 ) is likely to be Cu-rich as described above compared to the first bonding surface SJ1 of the heat sink 101 ( FIG. 2 ). This may lead to peeling for the following reasons.

[0084] The first bonding surface SJ1 is the boundary surface between the heat sink 11Z, which has a relatively large thermal expansion coefficient in the in-plane direction (the horizontal direction in FIG. 6 ), and the first insulating layer 21Z, which has a relatively small thermal expansion coefficient in the in-plane direction. Therefore, thermal stress is applied to the first bonding surface SJ1 under temperature changes. If the first bonding surface SJ1 is Cu-rich as described above, in other words, if the portion of the heat sink 11Z facing the first bonding surface SJ1 is Cu-rich relative to the average composition of the heat sink 11Z, the thermal expansion coefficient of that portion will be larger, and the thermal stress applied to the first bonding surface SJ1 will also be larger. This increase in thermal stress is thought to easily lead to delamination at the first bonding surface SJ1.

[0085] On the other hand, in the manufacturing method according to the first embodiment, in the green laminate G101 (FIG. 3), the unsintered W particles (more generally, high-melting-point metal particles) of the green heat sink G11 and the unsintered ceramic particles of the green insulating layer G21 are likely to be in contact with or adjacent to each other at the first contact surface GSJ1. Therefore, compared with the first bonding surface SJ1 of the heat sink 191 (FIG. 6), the first bonding surface SJ1 of the heat sink 101 (FIG. 2) is likely to be W-rich. Furthermore, as described above, a press pressure may be applied to the laminate of the green heat sink G11 and the green insulating layer G21. In this case, the ceramic particles and the W particles can be brought even closer together. Therefore, the first bonding surface SJ1 of the heat sink 101 (FIG. 2) is likely to be even W-rich. This may potentially suppress the occurrence of delamination for the following reasons.

[0086] The first bonding surface SJ1 is the boundary surface between the heat sink 11, which has a relatively large thermal expansion coefficient in the in-plane direction (the horizontal direction in FIG. 2 ), and the first insulating layer 21, which has a relatively small thermal expansion coefficient in the in-plane direction. Therefore, thermal stress is applied to the first bonding surface SJ1 under temperature changes. If the first bonding surface SJ1 is W-rich as described above, in other words, if the portion of the heat sink 11 facing the first bonding surface SJ1 is W-richer than the average composition of the heat sink 11, the thermal expansion coefficient of that portion will be smaller, and therefore the thermal stress applied to the first bonding surface SJ1 will also be smaller. This reduction in thermal stress is thought to suppress delamination at the first bonding surface SJ1.

[0087] According to the heat dissipation substrate 101 ( FIG. 2 ) of the first embodiment, first, the heat dissipation plate 11 has high thermal conductivity due to the inclusion of Cu and at least one high-melting-point metal selected from the group consisting of W and Mo. Furthermore, the conductor layer 31 has high thermal conductivity due to the inclusion of Cu and at least one high-melting-point metal selected from the group consisting of W and Mo. Furthermore, the first insulating layer 21 is made of ceramic, which facilitates ensuring high thermal conductivity and a high withstand voltage per unit thickness. This allows the first insulating layer 21 to be a thin layer made of a material with high thermal conductivity. As a result, the thermal resistance due to the first insulating layer 21 in the heat conduction from the conductor layer 31 to the heat dissipation plate 11 can be reduced. This allows the heat dissipation substrate 101 to achieve excellent heat dissipation characteristics.

[0088] Second, because first insulating layer 21 of heat dissipation substrate 101 is made of ceramic, it is easy to reduce the difference in the linear expansion coefficient between first insulating layer 21 and heat sink 11 and conductor layer 31, thereby making it less likely for delamination to occur between elements of heat dissipation substrate 101 under temperature changes. Furthermore, because first insulating layer 21 of heat dissipation substrate 101 is made of ceramic, it is easy to reduce the difference in the linear expansion coefficient between heat dissipation substrate 101 and electronic component 290 ( FIG. 1 ) mounted thereon. As a result, it is less likely for delamination to occur between elements of electronic device 201 under temperature changes during the process of mounting electronic component 290 on heat dissipation substrate 101 to manufacture electronic device 201, and during temperature changes in electronic device 201 after that process. This improves the reliability of heat dissipation substrate 101 and electronic device 201 using it under temperature changes.

[0089] Third, the heat sink 11 is made of a sintered body, and the conductor layer 31 is also made of a sintered body. This allows the heat sink 11 and the conductor layer 31 to be easily formed using a firing process. This improves the manufacturing efficiency of the heat sink substrate 101.

[0090] As described above, the heat dissipation substrate 101 and the electronic device 201 having excellent heat dissipation characteristics and high reliability under temperature changes can be obtained with high manufacturing efficiency.

[0091] The heat sink 11 and the first insulating layer 21 are sintered to each other at the first joint surface SJ1, and the first insulating layer 21 and the conductor layer 31 are sintered to each other at the second joint surface SJ2. This strengthens the bond between the heat sink 11 and the first insulating layer 21 and the bond between the first insulating layer 21 and the conductor layer 31. This makes it less likely that peeling will occur between the heat sink 11 and the first insulating layer 21 and between the first insulating layer 21 and the conductor layer 31 due to thermal stress. This further improves reliability under temperature changes.

[0092] When the electronic component 290 (FIG. 1) includes a power semiconductor element, the electronic component 290 is likely to generate a large amount of heat. In such a case, the above-described effect is more pronounced. The same is true when the electronic component 290 includes a semiconductor light-emitting element.

[0093] In a cross-sectional view of at least a portion of the second bonding surface SJ2 ( FIG. 4 ), the length ratio of the refractory metal section in the projection of the second boundary line onto a straight line along which the second bonding surface SJ2 extends macroscopically is greater than the area ratio of at least one refractory metal in the conductor layer 31. This large ratio allows the thermal expansion coefficient of the portion of the conductor layer 31 facing the first insulating layer 21 in the linear direction to approach the thermal expansion coefficient of the first insulating layer 21. This prevents the conductor layer 31 and the first insulating layer 21 from peeling from each other. For the refractory metal, the length ratio is preferably 1.3 times or more, more preferably 1.4 times or more, of the area ratio. This ratio may be 3 times or less, which prevents the proportion of copper in the second bonding surface SJ2 from becoming too small. This prevents the thermal resistance of the second bonding surface SJ2 from becoming excessively large in both the thickness direction and the direction perpendicular thereto.

[0094] Similarly, in a cross-sectional view of at least a portion of the first bonding surface SJ1, the length ratio of the refractory metal section in the projection of the first boundary line onto a straight line along which the first bonding surface SJ1 extends macroscopically is greater than the area ratio of at least one refractory metal in the heat sink 11. This large ratio allows the thermal expansion coefficient of the portion of the heat sink 11 facing the first insulating layer 21 in the linear direction to approach the thermal expansion coefficient of the first insulating layer 21. This prevents the heat sink 11 and the first insulating layer from peeling from each other. For the refractory metal, the length ratio is preferably 1.3 times or more, more preferably 1.4 times or more, of the area ratio. This ratio may be 3 times or less, which prevents the copper ratio at the first bonding surface SJ1 from being too small. This prevents the thermal resistance of the first bonding surface SJ1 from being excessively high in both the thickness direction and the direction perpendicular thereto.

[0095] According to the manufacturing method of the first preferred embodiment, the heat sink 11, the first insulating layer 21, and the conductor layer 31 are formed by simultaneous firing, thereby increasing the bonding strength between them.

[0096] <Modification of First Embodiment> The first insulating layer 21 ( FIG. 2 ) has a bottom surface (a surface including the first bonding surface SJ1) and a top surface (a surface including the second bonding surface SJ2) opposite the bottom surface in the thickness direction. As a modification of the heat dissipation substrate, a ground layer (not shown) electrically connected to the heat dissipation plate 11 may be provided on the top surface in addition to a conductor layer 31 electrically insulated from the heat dissipation plate 11. In this case, the electronic component 290 may be mounted on the conductor layer 31 away from the ground layer, or may be mounted on the conductor layer 31 and the ground layer so as to straddle the conductor layer 31 and the ground layer. The latter is also considered to be one form in which the electronic component 290 is mounted on a conductor layer.

[0097] Second Embodiment FIG. 9 is a cross-sectional view schematically illustrating the configuration of a heat dissipation substrate 102 according to a second embodiment. The heat dissipation substrate 102 includes the components of the heat dissipation substrate 101 ( FIG. 2 ) and further includes a second insulating layer 22. The second insulating layer 22 extends from the first insulating layer 21 and is joined to the side surface SS of the conductor layer 31. The second insulating layer 22 and the conductor layer 31 are sintered together at the side surface SS of the conductor layer 31. Such a side surface SS is obtained by forming the second insulating layer 22 and the conductor layer 31 by co-firing. The material of the second insulating layer 22 may be any of the materials described as the material of the first insulating layer 21 in the first embodiment, or may be the same material as the first insulating layer 21.

[0098] In the method for manufacturing the heat dissipation substrate 102, first, a green laminate G101 (FIG. 3: embodiment 1) is formed. Next, referring to FIG. 10, a green insulating layer G22 is formed, which will become the second insulating layer 22 by firing. This forms the green laminate G102. The heat dissipation substrate 102 is obtained by firing the green laminate G102.

[0099] The green insulating layer G22 may be formed by printing a paste so as to fill the gaps between the green conductor layers G31. Even when the green conductor layer G31 is thick (e.g., 50 μm or more), such as when a green sheet is used as the green conductor layer G31, the paste can be printed so as to sufficiently fill the gaps between the green conductor layers G31 by repeating printing. The green insulating layer G22 can also be formed by stacking green sheets. The paste for the conductor layer may be prepared by blending metal powder with additives, resin, solvent, etc., and further adding ceramic powder as needed, followed by kneading. The paste for the insulating layer may be prepared in a similar manner.

[0100] Note that, other than the above, the features are almost the same as the features of the first embodiment described above, so the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0101] According to the second embodiment, the second insulating layer 22 extending from the first insulating layer 21 is bonded to the side surface SS of the conductor layer 31. This allows the conductor layer 31 to be fixed not only by the first insulating layer 21 but also by the second insulating layer 22. This makes it difficult for the conductor layer 31 to peel off. This effect can be further enhanced if the surface of the second insulating layer 22 is flush with the mounting surface SM as shown in FIG. 9 . However, the surface of the second insulating layer 22 may be lower than the mounting surface SM.

[0102] Third Embodiment FIG. 11 is a cross-sectional view schematically illustrating the configuration of a heat dissipation substrate 103 according to a third embodiment. In addition to the configuration of the heat dissipation substrate 102 ( FIG. 9 ), the heat dissipation substrate 103 further includes a third insulating layer 23. The third insulating layer 23 extends from the second insulating layer 22 and partially covers the mounting surface SM of the conductor layer 31. A portion of the mounting surface SM is not covered by the third insulating layer 23. The third insulating layer 23 is partially bonded to the mounting surface SM of the conductor layer 31, thereby forming a third bonding surface SJ3. The third insulating layer 23 and the conductor layer 31 are sintered to each other at the third bonding surface SJ3. Such a third bonding surface SJ3 is obtained by forming the third insulating layer 23 and the conductor layer 31 by co-firing.

[0103] The width wd3 of the mounting surface SM covered by the third insulating layer 23 is preferably 5 μm or more. The thickness of the third insulating layer 23 is preferably 5 μm or more and 35 μm or less, and more preferably 5 μm or more and 20 μm or less. If the thickness is too small, variations in the thickness of the third insulating layer 23 are likely to become a problem. If the thickness is too large, heat dissipation from the conductor layer 31 is hindered. The material of the third insulating layer 23 may be any of the materials described as the material of the first insulating layer 21 in embodiment 1. For convenience of the manufacturing method described below, the material of the third insulating layer 23 is preferably the same as the material of the second insulating layer 22.

[0104] In the method for manufacturing the heat dissipation substrate 103, first, a green laminate G101 (FIG. 3: embodiment 1) is formed. In this case, in embodiment 3, the green conductor layer G31 is preferably formed by printing, and in this case, the thickness of the conductor layer 31 is, for example, 5 μm or more and 50 μm or less. Referring to FIG. 12 , next, green insulating layers G22 and G23, which will become the second insulating layer 22 and the third insulating layer 23, respectively, by firing, are formed by printing. This forms the green laminate G103. The heat dissipation substrate 103 is obtained by firing the green laminate G103.

[0105] An electron microscope photograph showing the vicinity of the third bonding surface SJ3 ( FIG. 11 ) between the third insulating layer 23 and the conductor layer 31 also has a configuration substantially similar to that of the second bonding surface SJ2 in the aforementioned electron microscope photograph ( FIG. 4 ). Therefore, in a cross-sectional view of at least a portion of the third bonding surface SJ3, the third bonding surface SJ3 extends macroscopically along a straight line, and microscopically forms an undulating third boundary line between the conductor layer 31 and the third insulating layer 23. On the mounting surface SM of the conductor layer 31 covered with the third insulating layer 23, the third boundary line has a copper section made of Cu and a refractory metal section made of at least one refractory metal. In the projection of the third boundary line onto the straight line, the proportion of the refractory metal section is greater than the area proportion of the at least one refractory metal in the conductor layer 31. For example, this proportion may be 1.1 times or more the area proportion. The inventors believe that applying the aforementioned pressure to the contact surface (the contact surface corresponding to the third bonding surface SJ3 in FIG. 11 ) where a pair of green members (specifically, the green insulating layer G23 and the green conductor layer G31 in FIG. 12 ) come into contact with each other may contribute to improving this ratio. Furthermore, the inventors believe that the ratio occupied by the high-melting-point metal section may be increased by increasing the firing temperature and firing time.

[0106] Note that other features than those described above are substantially the same as those of the first or second embodiment described above, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0107] According to the third embodiment, the mounting surface SM of the conductor layer 31 is partially covered by the third insulating layer 23 extending from the second insulating layer 22. This allows the conductor layer 31 to be fixed not only by the first insulating layer 21 and the second insulating layer 22 but also by the third insulating layer 23. This makes it possible to make the conductor layer 31 less likely to peel off.

[0108] The first insulating layer 21, the second insulating layer 22, and the third insulating layer 23 may be made of the same material, which can prevent peeling between these layers.

[0109] In the heat dissipation substrate 103 ( FIG. 11 ) according to the third embodiment, the conductor layer 31 has a side surface SS connecting the second bonding surface SJ2 and the mounting surface SM. In a modified heat dissipation substrate 103M ( FIG. 13 ), the conductor layer 31 has an end portion whose thickness gradually decreases toward the end ED3 of the conductor layer 31 so that the second bonding surface SJ2 and the mounting surface SM are directly connected to each other at the end ED3. As a result, the conductor layer 31 has a thickness th3 at a position away from the end ED3 (e.g., at least one position where the mounting surface SM is exposed and not covered by the third insulating layer 23), but has a thickness that is essentially zero at the end ED3. In this modified example, because the second bonding surface SJ2 and the mounting surface SM are directly connected, the conductor layer 31 does not have a side surface SS ( FIG. 11 ). Accordingly, the heat dissipation substrate of this modified example does not include the second insulating layer 22 ( FIG. 11 ). Accordingly, the third insulating layer 23 that partially covers the mounting surface SM of the conductor layer 31 extends from the second insulating layer 22 in the heat dissipation substrate 103 ( FIG. 11 ) according to the third embodiment, but in this modification, it extends from the first insulating layer 21. Note that in this modification, the first insulating layer 21 and the third insulating layer 23 may be made of the same material. This modification also provides the same effects as those of the third embodiment described above.

[0110] 14 is a cross-sectional view schematically illustrating the configuration of a heat dissipation substrate 104 according to a fourth embodiment. The heat dissipation substrate 104 has an internal electrode 40 embedded in a first insulating layer 21. The internal electrode 40 may include an internal layer portion 41 extending in an in-plane direction (lateral direction in FIG. 14 ) away from both main surfaces (top and bottom surfaces in FIG. 14 ) of the first insulating layer 21, and a via portion 42 connecting the internal layer portion 41 and the conductor layer 31. The internal electrode 40, together with the conductor layer 31, forms wiring, allowing the heat dissipation substrate 104 to have more complex wiring than the heat dissipation substrate 101 ( FIG. 2 ).

[0111] FIG. 15 is a cross-sectional view schematically illustrating one step in the manufacturing method of the heat dissipation substrate 104 (FIG. 14). First, a green laminate G104 is formed. The difference from the first embodiment described above is that instead of the simple green insulating layer G21 (FIG. 3: first embodiment), a green insulating layer G21 is formed in which a green internal electrode G40 having a green inner layer portion G41 and a green via portion G42 is embedded. This may be performed, for example, using well-known multilayer ceramic technology. The green laminate G104 is then fired to obtain the heat dissipation substrate 104.

[0112] Note that, other than the above, the features are almost the same as the features of the first embodiment described above, so the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0113] 16 is a cross-sectional view schematically illustrating the configuration of a heat dissipation substrate 104M, which is a modification of the heat dissipation substrate 104 (FIG. 14). In this modification, the first insulating layer 21 includes a first film 21a having a portion separating the heat dissipation plate 11 and the internal electrode 40M in the thickness direction (vertical direction in the figure), and a second film 21b having a portion separating the internal electrode (40M) and the conductor layer in the thickness direction and a hole HL between the internal electrode 40M and the conductor layer 31. The second film 21b has a thickness that gradually decreases toward the hole HL between the internal electrode 40M and the conductor layer 31 so that the internal electrode 40M and the conductor layer 31 are directly connected to each other at the hole HL. In this case, in the region between the internal electrode 40M and the conductor layer 31, the thickness does not need to gradually decrease toward the hole HL in the portion farther from the hole HL, and in the example shown in Fig. 16, the second film 21b has an approximately constant thickness th2. On the other hand, at the end ED2, the second film 21b has a thickness that is substantially zero. Unlike the internal electrode 40 (Fig. 14), the internal electrode 40M (Fig. 16) of this modified example does not need to have a via portion 42 (Fig. 14).

[0114] As a modified example of the heat dissipation substrate 104 (FIG. 14) or the heat dissipation substrate 104M (FIG. 16), the second insulating layer 22 (FIG. 9: embodiment 2), or the second insulating layer 22 and the third insulating layer 23 (FIG. 11: embodiment 3) may be applied.

[0115] Fifth Embodiment FIG. 17 is a cross-sectional view schematically illustrating a configuration of a heat dissipation substrate 105 according to the fifth embodiment. In the fifth embodiment, the heat dissipation plate 11 has a via hole VH connecting the first surface SF1 and the second surface SF2. The heat dissipation substrate 105 further includes an inner wall insulating layer 29 and a via electrode 39. The inner wall insulating layer 29 extends from the first insulating layer 21 and covers the inner wall SW of the via hole VH. The via electrode 39 extends from the conductor layer 31, penetrates the via hole VH in the heat dissipation plate 11, and is insulated from the heat dissipation plate 11 by the inner wall insulating layer 29. The heat dissipation substrate 105 may further include a back surface insulating layer 21T on the first surface SF1 of the heat dissipation plate 11 and a back surface conductor layer 31T on the back surface insulating layer 21T. The back surface conductor layer 31T is connected to the via electrode 39.

[0116] 18 is a cross-sectional view schematically illustrating one step in the manufacturing method of the heat dissipation substrate 105 (FIG. 17). First, a green laminate G105 is formed. The green laminate G105 differs from the previously described green laminate G101 (FIG. 3: embodiment 1) in that the green laminate G105 further includes a green inner wall insulating layer G29 that becomes the inner wall insulating layer 29 when fired, a green via electrode G39 that becomes the via electrode 39 when fired, a green back surface insulating layer G21T that becomes the back surface insulating layer 21T when fired, and a green back surface conductor layer G31T that becomes the back surface conductor layer 31T when fired. The heat dissipation substrate 105 is obtained by firing the green laminate G105.

[0117] Note that other features are substantially the same as those of the first embodiment described above, and therefore the same or corresponding elements are denoted by the same reference numerals, and their description will not be repeated. Alternatively, as a modification, the second insulating layer 22 ( FIG. 9 : second embodiment) or the second insulating layer 22 and the third insulating layer 23 ( FIG. 11 : third embodiment) may be applied to the heat dissipation substrate 105. Furthermore, an internal electrode 40 ( FIG. 14 : fourth embodiment) may be provided in the first insulating layer 21 of the heat dissipation substrate 105.

[0118] According to the fifth embodiment, the via electrodes 39 can provide the heat dissipation substrate 105 with an electrical path that connects the first surface SF1 and the second surface SF2.

[0119] <Study by Simulation> Thermal characteristics were studied by simulation for an example corresponding to the heat dissipation substrate 103 ( FIG. 11 : third embodiment) and a comparative example corresponding to a typical heat dissipation substrate 192 ( FIG. 19 ). FIG. 19 is a cross-sectional view showing the configuration of the heat dissipation substrate 192 of the second comparative example in this simulation. The heat dissipation substrate 192 has a heat sink 11Y, a first insulating layer 21Y, a second insulating layer 22Y, a third insulating layer 23Y, and a conductor layer 31Y. The second insulating layer 22Y and the third insulating layer 23Y correspond to the lower and upper portions of the insulating layer LR, respectively.

[0120] The materials and thickness conditions used in the simulation are shown in Table 1. In Table 1, MTCC stands for Middle Temperature Co-fired Ceramic, and refers to a ceramic material with a firing temperature of 1150°C to 1400°C, for example.

[0121]

[0122] The material choices and corresponding typical physical properties in the simulation are shown in Table 2 below.

[0123]

[0124] The simulation results of the thermal conductivity and linear expansion coefficient of the heat dissipation substrate are shown in Table 3 below.

[0125]

[0126] From the above results, it can be seen that the thermal resistance and the linear expansion coefficient can be suppressed according to this example.

[0127] 11: Heat sink 21: First insulating layer 21a: First film 21b: Second film 22: Second insulating layer 23: Third insulating layer 31: Conductive layer 41: Inner layer portion 42: Via portion 49: Via electrode 101-105, 103M, 104M: Heat sink substrate 201: Electronic device 290: Electronic component G101-G105: Green laminate G11: Green heat sink G21-G23: Green insulating layer G31: Green conductor layer HL: Hole SF1: First surface SF2: Second surface SJ1: First bonding surface SJ2: Second bonding surface SJ3: Third bonding surface SM: Mounting surface SS: Side surface VH: Via hole

Claims

1. A heat dissipation substrate on which an electronic component that generates heat is to be mounted, having a first surface and a second surface opposite to the first surface, containing copper and at least one refractory metal selected from the group consisting of tungsten and molybdenum, and being a sintered body, a heat dissipation plate for dissipating heat from the electronic component; a first insulating layer made of ceramic, having a thickness smaller than the thickness of the heat dissipation plate, and forming a first bonding surface by being bonded to the second surface of the heat dissipation plate; a conductor layer made of a sintered body, having a thickness smaller than the thickness of the heat dissipation plate, forming a second bonding surface by being bonded to the first insulating layer, having a mounted surface opposite to the second bonding surface on which the electronic component is to be mounted, and being electrically insulated from the heat dissipation plate by the first insulating layer, and containing copper and at least one refractory metal selected from the group consisting of tungsten and molybdenum. The heat dissipation substrate comprises the above components.

2. The heat dissipation substrate according to claim 1, wherein the heat dissipation plate and the first insulating layer are sintered to each other at the first bonding surface, and the first insulating layer and the conductor layer are sintered to each other at the second bonding surface.

3. The heat dissipation substrate according to claim 1, wherein the conductor layer has a side surface connecting the second bonding surface and the mounted surface to each other, and further comprises a second insulating layer extending from the first insulating layer and bonded to the side surface of the conductor layer.

4. The heat dissipation substrate according to claim 3, further comprising a third insulating layer extending from the second insulating layer and partially covering the mounted surface of the conductor layer.

5. The heat dissipation substrate according to claim 4, wherein the first insulating layer, the second insulating layer, and the third insulating layer are made of a common material.

6. The heat dissipation substrate according to claim 1, wherein the conductor layer has an end portion having a thickness gradually decreasing toward the end so that the second bonding surface and the mounted surface are directly connected to each other at the end of the conductor layer, and the heat dissipation substrate further comprises a third insulating layer extending from the first insulating layer and partially covering the mounted surface of the conductor layer.

7. The heat dissipation substrate according to claim 6, wherein the first insulating layer and the third insulating layer are made of a common material.

8. The heat dissipation substrate according to claim 1, wherein the heat dissipation plate has via holes connecting the first surface and the second surface to each other, an inner wall insulating layer extending from the first insulating layer and covering the inner wall of the via holes, and a via electrode extending from the conductor layer, passing through the via holes of the heat dissipation plate, and insulated from the heat dissipation plate by the inner wall insulating layer.

9. The heat dissipation substrate according to any one of claims 1 to 8, wherein in a cross-sectional view of at least a part of the first bonding surface, the first bonding surface macroscopically extends along a straight line and microscopically forms a first boundary line having undulations between the heat dissipation plate and the first insulating layer. The first boundary line has a copper section made of copper and a high melting point metal section made of the at least one high melting point metal. The length ratio occupied by the high melting point metal section in the projection of the first boundary line onto the straight line is larger than the area ratio of the at least one high melting point metal occupied by the heat dissipation plate in a cross-sectional view of at least a part of the first bonding surface.

10. The heat dissipation substrate according to any one of claims 1 to 8, wherein in a cross-sectional view of at least a part of the second bonding surface, the second bonding surface macroscopically extends along a straight line and microscopically forms a second boundary line having undulations between the first insulating layer and the conductor layer. The second boundary line has a copper section made of copper and a high melting point metal section made of the at least one high melting point metal. The length ratio occupied by the high melting point metal section in the projection of the second boundary line onto the straight line is larger than the area ratio of the at least one high melting point metal occupied by the conductor layer in a cross-sectional view of at least a part of the second bonding surface.

11. The heat dissipation substrate according to any one of claims 1 to 8, further comprising an internal electrode embedded in the first insulating layer and connected to the conductor layer.

12. The heat dissipation substrate according to claim 11, wherein the internal electrode includes an inner layer portion extending in a plane direction away from both main surfaces of the first insulating layer and a via portion connecting the inner layer portion and the conductor layer.

13. The heat dissipation substrate according to claim 11, wherein the first insulating layer includes a first film having a portion that separates the heat dissipation plate and the internal electrode in the thickness direction, a portion that separates the internal electrode and the conductor layer in the thickness direction, and a hole between the internal electrode and the conductor layer, and a second film, and the second film has a thickness that gradually decreases toward the hole so that the internal electrode and the conductor layer are directly connected to each other in the hole.

14. An electronic device comprising the heat dissipation substrate according to any one of claims 1 to 8 and the electronic component mounted on the conductor layer.

15. The electronic device according to claim 14, wherein the electronic component includes a power semiconductor element.

16. The electronic device according to claim 14, wherein the electronic component includes a semiconductor light emitting element.

17. A method for manufacturing a heat dissipation substrate for manufacturing the heat dissipation substrate according to any one of claims 1 to 8, the method comprising a step of forming a green laminate, the green laminate including a green heat dissipation plate that becomes the heat dissipation plate by firing, a green insulating layer that becomes the first insulating layer by firing, and a green conductor layer that becomes the conductor layer by firing, and further comprising a step of firing the green laminate.

Images