Composite component and method for producing composite component

Abstract

An internal electrode layer 40 contains copper and at least one high melting point metal selected from the group consisting of tungsten and molybdenum. A ceramic base portion 30 is joined to a first surface SF1 and a second surface SF2 of the internal electrode layer 40, and contains alumina as a main component. In at least one cross-sectional view parallel to the thickness direction, the first surface SF1 of the internal electrode layer 40 has a first copper section which comprises copper and a first high melting point metal section which comprises the at least one high melting point metal. In a projection of the first surface SF1 onto a straight line perpendicular to the thickness direction, the first high melting point metal section accounts for a first proportion. The second surface SF2 of the internal electrode layer 40 has a second copper section which comprises copper and a second high melting point metal section which comprises the at least one high melting point metal. In a projection of the second surface SF2 onto a straight line perpendicular to the thickness direction, the second high melting point metal section accounts for a second proportion. The first proportion is at least 10% greater than the second proportion.

Description

Composite part and method for manufacturing the same

[0001] The present invention relates to a composite part, and more particularly to a composite part having a ceramic substrate and internal electrode layers.

[0002] International Publication No. 2016 / 148217 (Patent Document 1) discloses a wiring board having an insulating substrate, a surface wiring layer disposed on the surface of the insulating substrate, and an internal wiring layer disposed inside the insulating substrate. ２ O ３ The surface wiring layer and the internal wiring layer include copper and tungsten, copper and molybdenum, or copper, tungsten, and molybdenum.

[0003] International Publication No. 2016 / 148217

[0004] As mentioned above, alumina is widely used as the main component of insulating substrates. Furthermore, the material for internal wiring layers often contains copper. The thermal expansion coefficients of alumina and copper differ significantly, which can lead to the internal electrode layers peeling off from the ceramic substrate due to thermal stress. Thermal stress can occur not only due to temperature changes in the environment in which the wiring board is used, but also due to temperature changes during the manufacturing process of the wiring board. If the influence of thermal stress due to the latter is significant, peeling may be more likely to occur during use of the wiring board, even if peeling did not occur during manufacturing. For example, peeling may occur due to some kind of impact.

[0005] In the above-mentioned wiring board (composite component), the internal wiring layer (internal electrode layer) has a pair of surfaces opposite each other in the thickness direction. Depending on the structure and / or manufacturing method of the composite component, peeling of one of the pair of surfaces of the internal electrode layer may be sufficiently prevented, but peeling of the other may not be sufficiently prevented. This is because one orientation (e.g., positive Z orientation) and the other orientation (negative Z orientation) in the thickness direction (e.g., Z direction) are often not equivalent to each other for the structure and / or manufacturing method of the composite component. This inequality may result in one of the pair of surfaces having lower adhesion or being more susceptible to greater stress than the other, making the one surface more susceptible to peeling than the other surface. In this case, it would be useful to apply some technology to prevent peeling of one specific surface of the pair of surfaces of the internal electrode layer. However, such technology has not been fully explored to date.

[0006] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a composite part and a method for manufacturing the composite part that can prevent peeling of one specific surface of a pair of surfaces of an internal electrode layer that are opposite to each other in a thickness direction.

[0007] Aspect 1 comprises an internal electrode layer having a first surface and a second surface opposite to each other in a thickness direction, the internal electrode layer containing copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum, and a ceramic base portion joined to the first surface and the second surface of the internal electrode layer and containing alumina as a main component, wherein in at least one cross-sectional view parallel to the thickness direction, the first surface of the internal electrode layer has a first copper section made of copper and a first high-melting-point metal section made of the at least one high-melting-point metal, and the first high-melting-point metal section occupies a first proportion in a projection of the first surface onto a straight line perpendicular to the thickness direction, and the second surface of the internal electrode layer has a second copper section made of copper and a second high-melting-point metal section made of the at least one high-melting-point metal, and the second proportion is 10% or more larger than the second proportion.

[0008] Aspect 2 is the composite part according to aspect 1, wherein the internal electrode layers contain 10 wt % or more and 85 wt % or less of the copper with respect to the total weight of the copper and the at least one high-melting-point metal.

[0009] Aspect 3 is a composite part according to aspect 1 or 2, wherein the internal electrode layer has a metal portion containing the copper and the at least one high-melting-point metal, and a ceramic portion dispersed in the metal portion, and the ceramic portion accounts for 1 wt % or more and 20 wt % or less of the total weight of the metal portion and the ceramic portion.

[0010] Aspect 4 is the composite part according to any one of aspects 1 to 3, wherein the first ratio is greater than the second ratio by 20% or more.

[0011] Aspect 5 is a manufacturing method of a composite part including internal electrode layers having first and second surfaces opposite to each other in a thickness direction, and containing copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum, and ceramic base portions joined to the first and second surfaces of the internal electrode layers, the manufacturing method comprising: a step of forming a green structure having electrode green layers that become the internal electrode layers by being fired, and green base portions that become the ceramic base portions by being fired; and a step of firing the green structure to form the composite part from the green structure, wherein the green base portions are in contact with the first surfaces of the electrode green layers, and １ Volume percent ceramic components and R １ a first ceramic green layer containing an organic component of vol. %; and a second ceramic green layer contacting the second surface of the electrode green layer, Ｇ Volume percent ceramic components and R Ｇ a composition gradient-inducing layer containing an organic component in an amount of 0.01% by volume; Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) is smaller than

[0012] Aspect 6 is a method for producing a composite part according to aspect 5, comprising: Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) is less than 90%.

[0013] Aspect 7 is the method for producing a composite part according to aspect 5 or 6, wherein the green substrate portion is in contact with the composition gradient inducing layer so as to face the second surface of the electrode green layer via the composition gradient inducing layer, and C ２ Volume percent ceramic components and R ２ a second ceramic green layer containing an organic component in an amount of 100% by volume; Ｇ / (C Ｇ +R Ｇ ) is C ２ / (C ２ +R ２) is smaller than

[0014] Aspect 8 is a method for manufacturing a composite part as described in Aspect 7, wherein the step of forming the green structure includes a step of forming a first substructure having the first ceramic green layer and the electrode green layer, a step of forming a second substructure having the second ceramic green layer and the composition gradient inducing layer, and a step of stacking the first substructure and the second substructure on each other.

[0015] Aspect 9 is a method for manufacturing a composite part according to aspect 7, wherein the step of forming the green structure includes the steps of forming a partial structure having the first ceramic green layer, the electrode green layer, and the composition gradient inducing layer, and stacking the partial structure and the second ceramic green layer on top of each other.

[0016] Aspect 10 is a method for manufacturing a composite part as described in Aspect 7, wherein the step of forming the green structure includes a step of forming a partial structure having the second ceramic green layer, the composition gradient inducing layer, and the electrode green layer, and a step of stacking the partial structure and the first ceramic green layer on top of each other.

[0017] According to the first aspect, the first ratio of the first high-melting-point metal sections of the first surfaces of the internal electrode layers is 10% or more greater than the second ratio of the second high-melting-point metal sections of the second surfaces of the internal electrode layers. This makes it easier to reduce the difference between the expansion and / or contraction of the first surfaces of the internal electrode layers and the expansion and / or contraction of the ceramic base portion in a direction perpendicular to the thickness direction. This prevents the first surfaces of the internal electrode layers from peeling off from the ceramic base portion.

[0018] According to aspect 2, first, the internal electrode layers contain 10 wt % or more of copper relative to the total weight of copper and the at least one high-melting-point metal. This allows the physical properties of copper to be fully utilized for the internal electrode layers. Second, the internal electrode layers contain 85 wt % or less of copper relative to the total weight of copper and the at least one high-melting-point metal. In other words, the internal electrode layers contain 15 wt % or more of at least one high-melting-point metal relative to the total weight of copper and the at least one high-melting-point metal. This makes it easier for the degree of expansion and / or contraction of the internal electrode layers to approach the degree of expansion and / or contraction of the ceramic base portion. Therefore, peeling of the first surface of the internal electrode layer from the ceramic base portion is more reliably prevented.

[0019] According to aspect 3, the internal electrode layer has a ceramic portion, and the ceramic portion occupies 1% by weight or more and 20% by weight or less of the total weight of the metal portion and the ceramic portion. This makes it possible to further strengthen the bond between the internal electrode layer and the ceramic base portion. Therefore, peeling of the first surface of the internal electrode layer from the ceramic base portion is more reliably prevented.

[0020] According to aspect 4, the first ratio is greater than the second ratio by 20% or more, which more reliably prevents the first surfaces of the internal electrode layers from peeling off from the ceramic base portion.

[0021] According to aspect 5, C Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) is smaller than the ratio of tungsten in the first surface of the internal electrode layer. This makes it possible to induce a composition gradient in which the ratio of tungsten in the first surface of the internal electrode layer is larger than the ratio of tungsten in the second surface of the internal electrode layer. Therefore, it becomes easier to make the degree of expansion and / or contraction of the internal electrode layer in the first surface closer to the degree of expansion and / or contraction of the ceramic base portion. Therefore, peeling of the first surface of the internal electrode layer 40 from the ceramic base portion is prevented.

[0022] According to aspect 6, C Ｇ / (C Ｇ+R Ｇ ) is C １ / (C １ +R １ ) is 90% or less. This makes it possible to more reliably induce the composition gradient. Therefore, peeling of the first surfaces of the internal electrode layers from the ceramic substrate is more reliably prevented.

[0023] According to aspect 7, a second ceramic green layer is also disposed on the second surface of the electrode green layer in addition to the composition gradient inducing layer, and C ２ / (C ２ +R ２ ) is C Ｇ / (C Ｇ +R Ｇ ) is larger than the volume fraction of the ceramic component in the green structure at a position separated from the second surface of the electrode green layer by the composition gradient inducing layer. This makes it possible to avoid problems caused by excessive formation of portions with a small volume fraction of the ceramic component.

[0024] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0025] FIG. 1 is a cross-sectional view schematically illustrating the configuration of a composite part according to an embodiment. FIG. 2 is an electron microscope photograph partially illustrating the configuration of the composite part of FIG. 1 in a cross-sectional view parallel to the thickness direction. FIG. 3 is a diagram illustrating the first high-melting-point metal section, the first copper section, the second high-melting-point metal section, and the second copper section in the electron microscope photograph of FIG. 2. FIG. 4 is a flow diagram schematically illustrating a method for manufacturing the composite part of FIG. 1. FIG. 5 is a flow diagram more specifically illustrating the process of forming the green structure of FIG. 4. FIG. 6 is a cross-sectional view schematically illustrating the process of forming the first substructure and the process of forming the second substructure of FIG. 5. FIG. 7 is a cross-sectional view schematically illustrating the process of stacking the first substructure and the second substructure of FIG. 5. FIG. 8 is a flow diagram illustrating a first modified example of FIG. 5. FIG. 9 is a cross-sectional view schematically illustrating the substructures and the second ceramic green layer to be stacked on top of each other of FIG. 8. FIG. 10 is a flow diagram illustrating a second modified example of FIG. 5. Fig. 11 is a cross-sectional view schematically showing the partial structures and the first ceramic green layer to be stacked on each other in Fig. 10. Fig. 12 is a partial cross-sectional view schematically showing a wiring board as an example of a composite part.

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, in which the same or corresponding parts are designated by the same reference numerals and will not be described repeatedly.

[0027] <Structure> Fig. 1 is a cross-sectional view schematically showing the configuration of a composite component 100 according to an embodiment. The composite component 100 has a ceramic base portion 30 and internal electrode layers 40. The internal electrode layers 40 have a first surface SF1 and a second surface SF2 that are opposite to each other in the thickness direction. The ceramic base portion 30 is bonded to the first surface SF1 and the second surface SF2 of the internal electrode layers 40. More specifically, the ceramic base portion 30 is sintered and bonded to the first surface SF1 and the second surface SF2 of the internal electrode layers 40.

[0028] The ceramic base 30 contains alumina as a main component. The ceramic base 30 may contain additional components in addition to the main component. The additional components may contain silicon oxide and manganese oxide. The composition analysis of the ceramic base 30 may be performed by energy dispersive X-ray spectroscopy (EDX). When the ceramic base 30 is substantially composed of alumina as a main component and silicon oxide and manganese oxide as additional components, the atomic concentrations of Al, Si, and Mn are measured by EDX. Each of Al atoms, Si atoms, and Mn atoms has a concentration of Al. ２ O ３ , SiO ２ and MnO, the total weight of silicon oxide and manganese oxide relative to the weight of the ceramic base 30 may be 11.0% by weight or more and 30.0% by weight or less, and the weight of silicon oxide relative to the total weight of silicon oxide and manganese oxide may be 54.0% by weight or more and 66.6% by weight or less.

[0029] Fig. 2 is an electron microscope photograph partially showing the configuration of the composite part 100 in a cross section parallel to the thickness direction (the vertical direction in Fig. 1 ). As will be described in detail later, in Fig. 2, the black parts are the ceramic base part 30 and the ceramic parts 43 of the internal electrode layers 40. The gray parts are the copper matrix 41C of the internal electrode layers 40. The white parts are the tungsten particles 41W of the internal electrode layers 40.

[0030] 2, the internal electrode layer 40 has a ceramic portion 43 in addition to a metal portion 41. The internal electrode layer 40 may consist of only the metal portion 41 and the ceramic portion 43. If the effect of the ceramic portion 43, which will be described later, is not required, the ceramic portion 43 may be omitted, and in that case, the internal electrode layer 40 may consist of only the metal portion 41. The composition of the ceramic portion 43 is preferably substantially the same as the composition of the ceramic base portion 30. The main component of the ceramic portion 43 may be alumina.

[0031] The metal portion 41 contains copper and at least one high-melting-point metal selected from the group consisting of tungsten and molybdenum (in other words, copper and / or molybdenum). The metal portion 41 may consist only of copper and at least one high-melting-point metal. In this embodiment, the case where the at least one high-melting-point metal is tungsten is described in detail, but molybdenum may be used instead of or together with tungsten.

[0032] In the example shown in Fig. 2, the metal portion 41 is a copper-tungsten alloy. Since copper and tungsten do not form a solid solution, the alloy is a composite material of copper and tungsten, taking its microscopic structure into consideration. As shown in Fig. 2, the composite material may have a structure in which tungsten particles 41W are dispersed in a copper matrix 41C. Adjacent tungsten particles 41W may be sintered together.

[0033] Fig. 3 is a diagram illustrating the first high-melting-point metal section, the first copper section, the second high-melting-point metal section, and the second copper section in the electron microscope photograph of Fig. 2. The first surface SF1 and the second surface SF2 of the internal electrode layer 40 may be straight lines that are approximately perpendicular to the thickness direction as shown in Fig. 1 macroscopically, but have fine irregularities approximately the same size as the particle diameter of the tungsten particles 41W as shown in Figs. 2 and 3 microscopically.

[0034] The first surface SF1 of the internal electrode layer 40 has a first copper section made of copper (specifically, the copper matrix 41C) and a first high-melting-point metal section made of tungsten (specifically, tungsten particles 41W). In the figure, the "W" portion and the "Cu" portion in the lower dashed line are projections of the first copper section and the first high-melting-point metal section of the first surface SF1 onto a straight line perpendicular to the thickness direction. Similarly, the second surface SF2 of the internal electrode layer 40 has a second copper section made of copper (specifically, the copper matrix 41C) and a second high-melting-point metal section made of tungsten (specifically, the tungsten particles 41W). In the figure, the "W" portion and the "Cu" portion in the upper dashed line are projections of the second copper section and the second high-melting-point metal section of the second surface SF2 onto a straight line perpendicular to the thickness direction.

[0035] The ceramic portion 43 is a portion formed from ceramic powder dispersed in the electrode paste described below. It is clear that the ceramic portion of the internal electrode layer 40 completely surrounded by the metal portion 41 is formed from the ceramic powder of the electrode paste. However, it can be difficult to determine whether the ceramic portion not completely surrounded by the metal portion 41 near the first surface SF1 is formed from the ceramic powder of the electrode paste or the ceramic base portion 30. Because the proportion of the ceramic portion 43 in the internal electrode layer 40 is relatively small, even if the ceramic portion is considered to belong entirely to the ceramic base portion 30, this often does not substantially affect the results of the evaluation related to the projection. However, in some cases, if the ceramic portion is considered to be the ceramic base portion 30, the first surface SF1 may be defined as having a significantly complicated shape. In such cases, the projection of the first copper section and the projection of the first high-melting-point metal section may overlap to a non-negligible extent on the straight line. In such cases, the corresponding cross-sectional portion may be ignored, and evaluation may be performed using another cross-sectional portion. The same applies to the vicinity of the second surface SF2.

[0036] In the projection of the first surface SF1 onto a line perpendicular to the thickness direction, the first high-melting-point metal section occupies a first proportion (see the "W" portion of the lower dashed line in the figure). In the projection of the second surface SF2 onto a line perpendicular to the thickness direction, the second high-melting-point metal section occupies a second proportion (see the "W" portion of the upper dashed line in the figure). The first proportion is 10% or more larger than the second proportion, preferably 20% or more larger. Specifically, the first proportion may be 20% or more larger than the second proportion. The width dimension of the image used to calculate the first and second proportions (the horizontal dimension of the field of view in FIG. 3) is, for example, 20 μm or more and 40 μm or less.

[0037] The metal portion 41 of the internal electrode layer 40 may contain 10 wt % to 85 wt % copper relative to the total weight of copper and tungsten. More preferably, the metal portion 41 of the internal electrode layer 40 may contain 15 wt % to 85 wt % copper relative to the total weight of copper and tungsten. The ceramic portion 43 may account for 1 wt % to 20 wt % of the total weight of the metal portion 41 and the ceramic portion 43. In the above-mentioned composition specification, the metal portion 41 may be composed essentially of copper and tungsten only, in which case an internal electrode layer 40 with a low electrical resistance value can be formed. The weight percentage of the composition of the internal electrode layer 40 may be measured by EDX.

[0038] <Manufacturing Method> Figure 4 is a flow diagram that schematically shows a method for manufacturing the composite part 100 of Figure 1. In step ST100 (Figure 4), a green structure G100 (see Figure 7 described below) is formed. In step ST200 (Figure 4), the green structure G100 is fired. As a result, the composite part 100 (Figure 1) is formed from the green structure G100.

[0039] 5 is a flow chart showing step ST100 (FIG. 4) in more detail. Step ST100 will be described in more detail below with reference to this flow chart.

[0040] 6, in step ST111 (FIG. 5), a first substructure UN1 having a first ceramic green layer GC1 and an electrode green layer G40 is formed. In addition, in step ST112 (FIG. 5), a second substructure UN2 having a second ceramic green layer GC2 and a composition gradient inducing layer GG is formed. Note that the order of steps ST111 and ST112 is arbitrary.

[0041] In this specification, "green" is a term widely used in ceramic engineering and refers to a raw state before firing. The electrode green layer G40 is a layer that will become the internal electrode layer 40 when fired. Therefore, like the internal electrode layer 40, the electrode green layer G40 also has a first surface SF1 and a second surface SF2. The green substrate part G30 (see FIG. 7 described later) having the first ceramic green layer GC1, the second ceramic green layer GC2, and the composition gradient induction layer GG becomes the ceramic substrate part 30 ( FIG. 1 ) when fired.

[0042] The composition gradient induction layer GG is also a type of green layer. The thickness of the composition gradient induction layer GG may be smaller than the thickness of the first ceramic green layer GC1. The thickness of the composition gradient induction layer GG may also be smaller than the thickness of the second ceramic green layer GC2. The thickness of the composition gradient induction layer GG may also be larger than the thickness of the electrode green layer G40. The thickness of the first ceramic green layer GC1 may be 30 μm or more and 500 μm or less. The thickness of the second ceramic green layer GC2 may be 30 μm or more and 500 μm or less. The thickness of the electrode green layer G40 may be 1 μm or more and 30 μm or less.

[0043] To obtain the first substructure UN1, a first ceramic green layer GC1 is first formed by a tape casting method (e.g., a doctor grade method). Next, an electrode green layer G40 is formed on the first ceramic green layer GC1 by printing (e.g., screen printing) an electrode paste. Multiple powders are dispersed in the electrode paste. The multiple powders include tungsten powder and copper powder as main components. The multiple powders may contain additional components in addition to the main components. At least a portion of the additional components may be ceramic powder. The ceramic powder may be for forming the ceramic portion 43 (FIG. 2).

[0044] To obtain the second substructure UN2, first, a second ceramic green layer GC2 is formed by a tape casting method (e.g., a doctor grade method). Next, a composition gradient inducing layer GG is formed on the second ceramic green layer GC2 by printing (e.g., screen printing) or by lamination. The former is suitable when the thickness of the composition gradient inducing layer GG is relatively small. The latter is suitable when the thickness of the composition gradient inducing layer GG is relatively large. In the latter case, the composition gradient inducing layer GG to be laminated is formed in advance by a tape casting method (e.g., a doctor grade method).

[0045] 7, in step ST113 (FIG. 5), the first substructure UN1 and the second substructure UN2 (FIG. 6) are stacked on top of each other. This forms a green structure G100 in which the first substructure UN1 and the second substructure UN2 are combined. To further adhere the first substructure UN1 and the second substructure UN2 to each other, pressure may be applied to the green structure G100 in the thickness direction. This pressure causes the electrode green layer G40 to be sufficiently embedded in the green base portion G30.

[0046] In the green substrate portion G30, the first ceramic green layer GC1 is in contact with the first surface SF1 of the electrode green layer G40, and the composition gradient induction layer GG is in contact with the second surface SF2 of the electrode green layer G40. １ Volume percent ceramic components and R １The composition gradient inducing layer GG contains an organic component of C Ｇ Volume percent ceramic components and R Ｇ % by volume of organic components. Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) is smaller. In other words, the volume fraction of the ceramic component in the composition gradient induction layer GG is smaller than the volume fraction of the ceramic component in the first ceramic green layer GC1. As a result of intensive research, the inventors have discovered that when the volume fraction of the ceramic component in the composition gradient induction layer GG is smaller than the volume fraction of the ceramic component in the first ceramic green layer GC1, the proportion of W (and / or Mo) becomes higher on the first surface SF1 side than on the second surface SF2 side. C Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) may be 52% or more and 90% or less.

[0047] In the green substrate portion G30, the second ceramic green layer GC2 is in contact with the composition gradient inducing layer GG so as to face the second surface SF2 of the electrode green layer G40 via the composition gradient inducing layer GG. ２ Volume percent ceramic components and R ２ % by volume of organic components. Ｇ / (C Ｇ +R Ｇ ) is C ２ / (C ２ +R ２ ) is smaller than C Ｇ / (C Ｇ +R Ｇ ) is C ２ / (C ２ +R ２ ) may be 52% or more and 90% or less.

[0048] C Ｇ / (C Ｇ +R Ｇ ) may be 0.43 or more and 0.61 or less. １ / (C１ +R １ ) and C ２ / (C ２ +R ２ ) may each be equal to or greater than 0.67 and equal to or less than 0.82.

[0049] The organic components of each of the first ceramic green layer, the second ceramic green layer GC2, and the composition gradient induction layer GG contain a resin. This resin may contain a plasticizer. The resin may also contain a dispersant. The dispersant serves to disperse the ceramic powder well in the solvent in the slurry used to form these layers.

[0050] The ceramic components of the composition gradient induction layer GG and the second ceramic green layer GC2 may be the same as each other. The ceramic components of the second ceramic green layer GC2 and the first ceramic green layer GC1 may be the same as each other. The main component of these ceramic components may be alumina powder, and its average particle size is preferably 0.4 μm or more and 2.5 μm or less, more preferably 1.3 μm or more and 1.7 μm or less.

[0051] When the internal electrode layer 40 has a ceramic portion 43 (FIG. 2), the electrode green layer G40 contains a corresponding ceramic component. The main component of the ceramic component may be alumina powder, and its average particle size is preferably 0.4 μm or more and 2.5 μm or less, more preferably 0.5 μm or more and 1.0 μm or less. The average particle size of the alumina powder as the main component of the ceramic component of the electrode green layer G40 is preferably smaller than the average particle size of the alumina powder as the main component of the composition gradient induction layer GG. The average particle size of the alumina powder as the main component of the ceramic component of the electrode green layer G40 is preferably smaller than the average particle size of the alumina powder as the main component of the first ceramic green layer GC1. The average particle size of the alumina powder as the main component of the ceramic component of the electrode green layer G40 is preferably smaller than the average particle size of the alumina powder as the main component of the second ceramic green layer GC2.

[0052] A method for forming the electrode paste used for printing the internal electrode layers 40 will now be described.

[0053] First, multiple powders are prepared as described above. Specifically, tungsten powder and copper powder are each prepared as main components. Ceramic powder is also prepared as needed. Next, these multiple powders are mixed in a powder mixing process to produce a mixed powder. This mixed powder is mixed with a resin, a solvent, and, if needed, an additive, in a paste mixing process to form an electrode paste. Alternatively, some of the multiple powders may be mixed with other portions of the multiple powders in the paste mixing process. Alternatively, the electrode paste may be formed in a single mixing process in which unmixed multiple powders are mixed with a resin, a solvent, and, if needed, an additive.

[0054] The average particle size of the tungsten powder may be 0.5 μm or more and 10 μm or less, preferably 0.5 μm or more and 3 μm or less, and more preferably 0.5 μm or more and 1.5 μm or less. When the average particle size is 0.5 μm or more, the cost of the tungsten powder can be reduced, and the electrical resistance (or thermal resistance) of the internal electrode layers 40 can also be reduced. When the average particle size is 10 μm or less, the adhesion between the ceramic base portion 30 and the internal electrode layers 40 can be improved. The average particle size of the tungsten powder to be used as a material for the electrode paste may be measured using the Fischer method.

[0055] The average particle size of the copper powder may be 1.5 μm or more and 5.0 μm or less. When the average particle size is 1.5 μm or more, the cost of the copper powder can be reduced. When the average particle size is 5.0 μm or less, the thickness and composition of the internal electrode layer 40 can be made more uniform. The particle size of the copper powder to be used as a material for the electrode paste may be measured using a laser diffraction method, for example, by stirring the powder in isopropyl alcohol (IPA) for 1 minute and then measuring it with a nanoparticle size distribution measuring device SALD-7500nano (manufactured by Shimadzu Corporation).

[0056] The firing temperature for obtaining the composite part 100 from the green structure G100 may be 1100°C or higher and 1400°C or lower. By setting the firing temperature to 1100°C or higher, the electrode green layer G40 can be heated to a temperature equal to or higher than the melting point of copper. This allows the internal electrode layer 40 to be formed from the electrode green layer G40 with high quality. On the other hand, by setting the firing temperature to 1400°C or lower, process difficulties caused by an excessively high firing temperature can be avoided.

[0057] In the ceramic base 30 (FIG. 1) obtained by firing the green base G30 (FIG. 7) including the three elements, the composition gradient induction layer GG, the first ceramic green layer GC1, and the second ceramic green layer GC2, it is often difficult or impossible to determine the positions of the boundaries between the three elements by ordinary microscopic observation. In particular, when the ceramic components of the three elements have approximately the same composition, such determination is often difficult or impossible even when composition analysis is also used.

[0058] A first modified example of the manufacturing method according to the present embodiment will be described below with reference to FIGS. 8 and 9 . Note that FIGS. 8 and 9 in this modified example correspond to FIGS. 5 and 6 in the present embodiment. Referring to FIG. 9 , in step ST121 ( FIG. 8 ), a partial structure UNa is formed, which includes a first ceramic green layer GC1, an electrode green layer G40, and a composition gradient induction layer GG. Next, in step ST122 ( FIG. 8 ), the partial structure UNa and the second ceramic green layer GC2 are stacked on top of each other. This forms a green structure G100 ( FIG. 7 ).

[0059] A second modified example of the manufacturing method according to the present embodiment will be described below with reference to FIGS. 10 and 11 . Note that FIGS. 10 and 11 in this modified example correspond to FIGS. 5 and 6 in the present embodiment. Referring to FIG. 11 , in step ST131 ( FIG. 10 ), a partial structure UNb is formed, which includes a second ceramic green layer GC2, a composition gradient induction layer GG, and an electrode green layer G40. Next, in step ST132 ( FIG. 10 ), the partial structure UNb and the first ceramic green layer GC1 are stacked one on top of the other. This forms a green structure G100 ( FIG. 7 ).

[0060] Using the manufacturing method according to the present embodiment (FIGS. 4 to 7), samples 1 to 15 were produced as the composite part 100 (FIG. 1) with various compositions of the internal electrode layers 40 (FIG. 2). The size of the samples in the in-plane direction (direction perpendicular to the thickness direction) was 20 mm x 20 mm.

[0061] In addition, the C of the composition gradient induction layer GG Ｇ / (C Ｇ +R Ｇ ) was set to 0.45. １ / (C １ +R １ ) and C of the second ceramic green layer GC2 ２ / (C ２ +R ２ ) were each set to 0.7.

[0062] The composition gradient induction layer GG had a thickness of 15 μm after firing, the first ceramic green layer GC1 and the second ceramic green layer GC2 had a thickness of 300 μm after firing, and the electrode green layer G40 had a thickness of 7 μm after firing.

[0063] Table 1 below shows the above composition based on the total weight of Cu and W being 100% by weight, and Table 2 below shows the composition based on the total weight of metal portion 41 and ceramic portion 43 (FIG. 2) being 100% by weight.

[0064]

[0065]

[0066] Table 3 below shows the first and second ratios described in the above embodiment and the ratio of the first ratio to the second ratio.

[0067]

[0068] As can be seen from Table 3 above, the ratio of the first ratio to the second ratio was 1.1 or more for Samples 2 to 14 (Examples 1 to 13), in which the weight ratio of Cu to the total weight of Cu and W was in the range of 10 wt % to 85 wt %. In other words, the first ratio of these samples was 10% or more greater than the second ratio. Taking the results of Samples 1 to 15 as a whole into consideration, the inventors estimate that the first ratio will be 10% or more greater than the second ratio when the weight ratio of Cu to the total weight of Cu and W is in the range of 10 wt % to 85 wt %.

[0069] Furthermore, the ratio of the first ratio to the second ratio was 1.2 or more for Samples 3 to 14 (Examples 2 to 13), in which the weight ratio of Cu to the total weight of Cu and W was in the range of 15 wt % to 85 wt %. In other words, the first ratio of these samples was 20% or more greater than the second ratio.

[0070] On the other hand, in samples 1 and 15 (Comparative Examples 1 and 2), in which the weight ratio of Cu to the total weight of Cu and W was outside the range of 10 wt% to 85 wt%, no significant difference was observed between the first ratio and the second ratio.

[0071] From the above results, it was confirmed that by using the composition gradient inducing layer GG (FIG. 7) in the manufacture of the composite component 100, a composition gradient in the ratio of Cu to W can be imparted to the internal electrode layer 40 (FIG. 1).

[0072] In order to examine the ease of delamination at the interface between the first surface SF1 of the internal electrode layer 40 and the ceramic base portion 30, a bending load was applied to five composite components 100 corresponding to each of Samples 1 to 15, causing a crack along the thickness direction (the vertical direction in FIG. 1 ) to occur through the vicinity of the center of the composite component 100, thereby dividing the composite component 100 into two parts. Under the resulting impact, no delamination occurred at the interface between the ceramic base portion 30 and the first surface SF1 of the internal electrode layer 40 in any of the composite components 100 corresponding to Samples 2 to 14 (Examples 1 to 13). Specifically, when the divided pieces of these composite components 100 were visually observed, the first surface SF1 of the internal electrode layer 40 was not visible. In other words, the first surface SF1 was not exposed by delamination.

[0073] On the other hand, in some of the five composite components 100 corresponding to Sample 1 (Comparative Example 1), separation caused peeling at the interface between the ceramic base portion 30 and the first surface SF1 of the internal electrode layer 40. The same was true for Sample 15 (Comparative Example 2).

[0074] From the above, it is believed that providing the above-mentioned composition gradient leads to prevention of peeling on the first surface SF1.

[0075] <Specific Example of Composite Component> Figure 12 is a partial cross-sectional view schematically illustrating a wiring board 101 as an example of a composite component. The wiring board 101 has a structure similar to that of the composite component 100 (Figure 1) having the ceramic base portion 30 and the internal electrode layer 40, but also includes an additional electrode portion CP. In this example, the ceramic base portion 30 has a surface SCa and a surface SCb opposite each other in the thickness direction. The additional electrode portion CP includes a surface electrode layer 51A on the surface SCa, a via electrode 52A connecting the surface electrode layer 51A to the internal electrode layer 40, a surface electrode layer 51B on the surface SCb, and a via electrode 52B connecting the surface electrode layer 51B to the internal electrode layer 40. As a modified example, either the pair of the surface electrode layer 51A and the via electrode 52A or the pair of the surface electrode layer 51B and the via electrode 52B may be omitted. Alternatively, instead of or together with the via electrodes, electrodes arranged along the castellations formed on the side surfaces of the ceramic substrate 30, that is, castellation electrodes, may be used.

[0076] In the wiring board 101 as a composite component, the structure differs between the portion above and the portion below the internal electrode layer 40 in the figure. This structural difference may lead to a tendency for one of the surfaces SFa and SFb of the internal electrode layer 40 to peel more easily than the other in a typical conventional manufacturing method (a manufacturing method that does not apply a composition gradient inducing layer GG). Furthermore, in addition to or instead of such a structural difference, some factor in the manufacturing method may lead to this tendency. For example, if the surface SFa tends to peel more easily than the surface SFb in a typical conventional manufacturing method, applying the technology of the above-described embodiment with the surface SFa as the first surface SF1 makes the surface SFa, which was originally prone to peeling, less likely to peel. Therefore, it is possible to suppress the occurrence of a phenomenon in which at least one of the surfaces SFa and SFb peels off.

[0077] Whether surface SFa or surface SFb is more likely to peel when a conventional typical manufacturing method is applied can be easily investigated by carrying out a prototype using the conventional typical manufacturing method or a corresponding simulation. Therefore, the investigation does not require trial and error beyond the extent that would be expected of a person skilled in the art, nor does it require complex and highly sophisticated experiments.

[0078] <Effects> According to the composite component 100 of this embodiment, the first ratio of the first high-melting point metal sections of the first surface SF1 of the internal electrode layer 40 (see the "W" portion of the lower dashed line in FIG. 3 ) is greater than the second ratio of the second high-melting point metal sections of the second surface SF2 of the internal electrode layer 40 (see the "W" portion of the upper dashed line in FIG. 3 ) by 10% or more. This makes it easier to reduce the difference between the expansion and / or contraction of the first surface SF1 of the internal electrode layer 40 and the expansion and / or contraction of the ceramic base portion 30 in the direction perpendicular to the thickness direction (the lateral direction in FIG. 3 ). Therefore, peeling of the first surface SF1 of the internal electrode layer 40 from the ceramic base portion 30 is prevented.

[0079] The first ratio may be 20% or more greater than the second ratio. This more reliably prevents the first surface SF1 of the internal electrode layer 40 from peeling off from the ceramic base portion 30. From the viewpoint of this effect, there is no particular upper limit to this percentage. However, an excessively high percentage may weaken the bonding strength of the second surface SF2, and to avoid this, it is desirable that the percentage be 500% or less.

[0080] Regarding the composition of the internal electrode layer 40, first, the internal electrode layer 40 may contain 10 wt % or more of copper relative to the total weight of copper and tungsten. This allows the internal electrode layer 40 to fully utilize the physical properties of copper, particularly its low electrical resistivity. Second, the internal electrode layer 40 may contain 85 wt % or less of copper relative to the total weight of copper and tungsten. In other words, the internal electrode layer 40 may contain 10 wt % or more of tungsten relative to the total weight of copper and tungsten. This makes it easier for the degree of expansion and / or contraction of the internal electrode layer 40 to approach the degree of expansion and / or contraction of the ceramic base portion 30. Therefore, peeling of the first surface SF1 of the internal electrode layer 40 from the ceramic base portion 30 is more reliably prevented.

[0081] The internal electrode layer 40 may have a ceramic portion 43 ( FIG. 2 ). This can further strengthen the bond between the internal electrode layer 40 and the ceramic base portion 30. Therefore, peeling of the first surface SF1 of the internal electrode layer 40 from the ceramic base portion 30 is more reliably prevented. The ceramic portion 43 may account for 1% by weight or more and 20% by weight or less of the total weight of the metal portion 41 and the ceramic portion 43. By setting this percentage to 20% by weight or less, excessive electrical resistance of the internal electrode layer 40 is prevented. By setting this percentage to 1% by weight or more, the effect of increasing the adhesion of the internal electrode layer 40 to the ceramic base portion 30 by the ceramic portion 43 is more reliably obtained.

[0082] The thickness of the internal electrode layer 40 is preferably 1 μm or more and 25 μm or less, more preferably 2 μm or more and 20 μm or less, and further preferably 3 μm or more and 15 μm or less, which makes the internal electrode layer 40 less likely to break and peel off.

[0083] According to the manufacturing method of this embodiment, the C of the composition gradient inducing layer GG (FIG. 7) Ｇ / (C Ｇ +R Ｇ ) is the C of the first ceramic green layer GC1 (FIG. 7). １ / (C １ +R １) is smaller than the ratio of tungsten in the first surface SF1 of the internal electrode layer 40. As a result, as shown in FIG. 2, a composition gradient can be induced in which the ratio of tungsten in the first surface SF1 of the internal electrode layer 40 is larger than the ratio of tungsten in the second surface SF2 of the internal electrode layer 40. This makes it easier to bring the degree of expansion and / or contraction of the internal electrode layer 40 on the first surface SF1 closer to the degree of expansion and / or contraction of the ceramic base portion 30. This prevents the first surface SF1 of the internal electrode layer 40 from peeling off from the ceramic base portion 30.

[0084] Furthermore, C Ｇ / (C Ｇ +R Ｇ ) is C １ / (C １ +R １ ) or less. This makes it possible to more reliably induce the composition gradient. Therefore, peeling of the first surface SF1 of the internal electrode layer 40 from the ceramic base portion 30 is more reliably prevented. Note that CG / (CG+RG) may be 52% or more of C1 / (C1+R1). This makes it difficult for the difference in shrinkage between the composition gradient induction layer GG and the first ceramic green layer GC1 to become excessive during firing. Therefore, peeling at the interface between these layers is unlikely to occur.

[0085] In addition to the composition gradient inducing layer GG, a second ceramic green layer GC2 (FIG. 7) may also be disposed on the second surface SF2 of the electrode green layer G40. ２ / (C ２ +R ２ ) is C Ｇ / (C Ｇ +R Ｇ ) is larger than the volume fraction of the ceramic component in the green structure G100 at a position separated by the composition gradient inducing layer GG from the second surface SF2 of the electrode green layer G40. This makes it possible to avoid problems caused by excessive formation of portions with a small volume fraction of the ceramic component.

[0086] 30: Ceramic base portion 40: Internal electrode layer 41: Metal portion 41C: Copper matrix 41W: Tungsten particles 43: Ceramic portion 100: Composite component 101: Wiring board (composite component) G100: Green structure G30: Green base portion G40: Electrode green layer GC1: First ceramic green layer GC2: Second ceramic green layer GG: Composition gradient inducing layer SF1: First surface SF2: Second surface UN1: First partial structure UN2: Second partial structure UNa, UNb: Partial structures

Claims

1. A composite component having a first surface and a second surface opposite to each other in the thickness direction, an internal electrode layer containing copper and at least one high melting point metal selected from the group consisting of tungsten and molybdenum, and a ceramic substrate portion bonded to the first surface and the second surface of the internal electrode layer and containing alumina as a main component. In at least one cross-sectional view parallel to the thickness direction, the first surface of the internal electrode layer has a first copper section made of the copper and a first high melting point metal section made of the at least one high melting point metal. In the projection of the first surface onto a straight line perpendicular to the thickness direction, the first high melting point metal section occupies a first ratio. The second surface of the internal electrode layer has a second copper section made of the copper and a second high melting point metal section made of the at least one high melting point metal. In the projection of the second surface onto a straight line perpendicular to the thickness direction, the second high melting point metal section occupies a second ratio. The first ratio is 10% or more greater than the second ratio.

2. The composite component according to claim 1, wherein the internal electrode layer contains 10% by weight or more and 85% by weight or less of the copper based on the total weight of the copper and the at least one high melting point metal.

3. The composite component according to claim 1, wherein the internal electrode layer has a metal portion containing the copper and the at least one high melting point metal and a ceramic portion dispersed in the metal portion, and the ceramic portion occupies 1% by weight or more and 20% by weight or less based on the total weight of the metal portion and the ceramic portion.

4. The composite component according to any one of claims 1 to 3, wherein the first ratio is 20% or more greater than the second ratio.

5. A method for manufacturing a composite component, comprising: an internal electrode layer having first and second surfaces opposite to each other in the thickness direction and containing copper and at least one high melting point metal selected from the group consisting of tungsten and molybdenum; and a ceramic substrate portion joined to the first and second surfaces of the internal electrode layer, the method comprising: forming a green structure having an electrode green layer that becomes the internal electrode layer when fired and a green substrate portion that becomes the ceramic substrate portion when fired; and firing the green structure to form the composite component, wherein the green substrate portion includes: a first ceramic green layer in contact with the first surface of the electrode green layer and containing C １ volume% of a ceramic component and R １ volume% of an organic component; and a composition gradient inducing layer in contact with the second surface of the electrode green layer and containing C Ｇ volume% of a ceramic component and R Ｇ volume% of an organic component, and C Ｇ / (C Ｇ +R Ｇ ) is smaller than C １ / (C １ +R １ ). A method for manufacturing a composite component.

6. The method for manufacturing a composite part according to claim 5, wherein C Ｇ / (C Ｇ +R Ｇ ) is 90% or less of C １ / (C １ +R １ ), the method for manufacturing a composite part.

7. A method for manufacturing a composite component according to claim 5 or 6, wherein the green substrate portion is in contact with the composition gradient inducing layer so as to face the second surface of the electrode green layer through the composition gradient inducing layer, and includes a second ceramic green layer containing C ２ volume% of a ceramic component and R ２ volume% of an organic component, and C Ｇ / (C Ｇ +R Ｇ ) is smaller than C ２ / (C ２ +R ２ ), a method for manufacturing a composite component.

8. The method for manufacturing a composite component according to claim 7, wherein the step of forming the green structure includes forming a first partial structure having the first ceramic green layer and the electrode green layer, forming a second partial structure having the second ceramic green layer and the composition gradient inducing layer, and laminating the first partial structure and the second partial structure with each other.

9. A method for manufacturing a composite component according to claim 7, wherein the step of forming the green structure includes: a step of forming a partial structure having the first ceramic green layer, the electrode green layer, and the composition gradient inducing layer; and a step of laminating the partial structure and the second ceramic green layer with each other.

10. A method for manufacturing a composite component according to claim 7, wherein the step of forming the green structure includes: a step of forming a partial structure having the second ceramic green layer, the composition gradient inducing layer, and the electrode green layer; and a step of laminating the partial structure and the first ceramic green layer with each other.

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