Ceramic sintered substrate, light-emitting device, and method for manufacturing the same

Abstract

Provided is a method for manufacturing a ceramic sintered body substrate, the method including: preparing a ceramic substrate 1 in which a through-hole 2 is formed before firing (S11); disposing a first metal paste 3 in the through-hole (S12); and firing the ceramic substrate in which the first metal paste is disposed (S14). In the process for disposing the first metal paste, the first metal paste includes a plurality of first metal powders (4) and a plurality of active metal powders (50). The first metal powders include a metal powder (4a) that serves as a core, and a coating metal member (40b) that covers at least part of the metal powder, the coating metal member (40b) having a melting point lower than that of the metal powder. In the process for firing the ceramic substrate, the firing temperature is equal to or greater than 700°C and is less than the melting point of the metal powder.

Description

[Technical Field]

[0001] This disclosure relates to ceramic sintered substrates, light-emitting devices, and methods for manufacturing the same. [Background technology]

[0002] Conventionally, via materials used in ceramic substrates are known to have through-conductors mainly composed of silver and copper, in which a eutectic region of silver and copper exists in the metal layer-side region of the central region of the diameter, and a non-eutectic region of silver and copper exists in the central region of the central region of the diameter. Furthermore, via materials used in ceramic substrates are known to be filled with a first metal paste containing a metal (B) powder with a melting point higher than that of metal (A) with a melting point of 600°C to 1100°C and an activated metal, and a second metal paste containing metal (A) powder is laminated at a position in contact with the first metal paste (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6122561 [Patent Document 2] Patent No. 5922739 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The embodiments relating to this disclosure aim to provide highly reliable ceramic sintered substrates, light-emitting devices, and methods for manufacturing the same. [Means for solving the problem]

[0005] A method for manufacturing a ceramic sintered substrate disclosed in the embodiment includes preparing a ceramic substrate with through holes formed therein before firing, placing a first metal paste in the through holes, and firing the ceramic substrate with the first metal paste in place, wherein the first metal paste comprises a plurality of first metal powders and a plurality of active metal powders, the first metal powder having a core metal powder and a covering metal member having a lower melting point than the metal powder and covering at least a portion of the metal powder, and the firing temperature for firing the ceramic substrate is 700°C or higher and below the melting point of the metal powder.

[0006] Furthermore, the method for manufacturing a light-emitting device disclosed in the embodiment includes preparing a ceramic sintered substrate manufactured by the method for manufacturing a ceramic sintered substrate described above, and arranging a light-emitting element on the ceramic sintered substrate, wherein in preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, and in arranging the light-emitting element, the first metal body arranged in the through-hole and the light-emitting element are electrically connected directly or indirectly.

[0007] Furthermore, the method for manufacturing a light-emitting device disclosed in the embodiment includes preparing a ceramic sintered substrate manufactured by the method for manufacturing a ceramic sintered substrate described above, and arranging a light-emitting element on the ceramic sintered substrate, wherein in preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, and the conductive paste becomes a conductor, and in arranging the light-emitting element, the first metal body or the conductor arranged in the through-hole and the light-emitting element are electrically connected directly or indirectly.

[0008] Furthermore, the ceramic sintered substrate disclosed in the embodiment comprises a ceramic substrate having through holes and a first metal body disposed within the through holes, wherein the first metal body comprises a plurality of metal powders, a second metal, and a metal compound, the metal powders having a higher melting point than the second metal and being dispersed within the continuous second metal, the ceramic substrate having a reaction layer of the metal compound on the inner wall of the through holes, and having reactants of the metal compound at the grain boundaries of the metal powders.

[0009] Furthermore, the light-emitting device disclosed in the embodiment comprises the ceramic sintered substrate described above and a light-emitting element electrically connected to the first metal body of the ceramic sintered substrate. [Effects of the Invention]

[0010] According to embodiments of this disclosure, highly reliable ceramic sintered substrates, light-emitting devices, and methods for manufacturing the same can be provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic plan view showing a ceramic sintered substrate according to an embodiment. [Figure 2] This is a schematic cross-sectional perspective view showing the cross-section along line II-II in Figure 1. [Figure 3A] This is a schematic, enlarged cross-sectional view showing a state in which the first metal paste is placed in the through-hole of the ceramic sintered substrate according to the embodiment. [Figure 3B] Figure 3A is a schematic enlarged cross-sectional view showing the state of the first metal body obtained by sintering the ceramic sintered substrate. [Figure 4A] This is a magnified scanning electron microscope image showing the first metal body placed in a through-hole of a ceramic sintered substrate according to the embodiment. [Figure 4B] This is a magnified scanning electron microscope image showing the first metal body placed in a through-hole of a ceramic sintered substrate according to the embodiment. [Figure 5]It is a flowchart illustrating a method for manufacturing a ceramic sintered body substrate according to an embodiment. [Figure 6A] In the method for manufacturing a ceramic sintered body substrate according to an embodiment, it is a cross-sectional view schematically showing the prepared ceramic substrate. [Figure 6B] In the method for manufacturing a ceramic sintered body substrate according to an embodiment, it is a cross-sectional view schematically showing a state where a first metal paste is disposed in a through hole. [Figure 6C] In the method for manufacturing a ceramic sintered body substrate according to an embodiment, it is a cross-sectional view schematically showing a state where a conductive paste is disposed. [Figure 7] It is a cross-sectional view schematically showing a light-emitting device according to an embodiment. [Figure 8] It is a flowchart illustrating a method for manufacturing a light-emitting device according to an embodiment. [[ID=十六]] [Figure 9A] In the method for manufacturing a light-emitting device according to an embodiment, it is a cross-sectional view schematically showing the prepared ceramic sintered body substrate. [Figure 9B] In the method for manufacturing a light-emitting device according to an embodiment, it is a cross-sectional view schematically showing a state where a joining member is disposed on a ceramic sintered body substrate. [Figure 9C] In the method for manufacturing a light-emitting device according to an embodiment, it is a cross-sectional view schematically showing a state where a light-emitting element is disposed. [Figure 9D] In the method for manufacturing a light-emitting device according to an embodiment, it is a cross-sectional view schematically showing a state where a light reflection member is disposed. [Figure 10A] It is a perspective view showing a light-emitting device according to an embodiment as a light-emitting module. [Figure 10B] It is a cross-sectional view schematically showing a cross section at line XB-XB with a part of FIG. 10A omitted.

Embodiments for Carrying Out the Invention

[0012] [[ID=四十]] The embodiments of this disclosure will be described below with reference to the drawings. However, the embodiments described below are intended to embody the technical idea of ​​this disclosure and, unless otherwise specified, the invention is not limited to the embodiments described below. The content described in one embodiment is applicable to other embodiments and modifications. In addition, the drawings provide a schematic representation of the embodiments, and in order to clarify the explanation, the scale, spacing, positional relationships of each component may be exaggerated, or some components may be omitted from the illustration. The directions shown in each figure indicate the relative positions between components and are not intended to indicate absolute positions. In principle, the same names and reference numerals indicate the same or similar components, and detailed explanations are omitted as appropriate. Also, in the embodiments, "covering" is not limited to direct contact, but also includes indirect covering, for example, through other components.

[0013] [Ceramic sintered substrate] A ceramic sintered substrate 10 according to the embodiment will be described with reference to Figures 1A to 4B. Figure 1 is a schematic plan view showing the ceramic sintered substrate according to the embodiment, and Figure 2 is a schematic cross-sectional perspective view showing the ceramic sintered substrate according to the embodiment. Figure 3A is an enlarged cross-sectional view schematically showing the state in which the first metal paste is placed in the through hole of the ceramic sintered substrate according to the embodiment. Figure 3B is an enlarged cross-sectional view schematically showing the state of the first metal body after sintering the ceramic sintered substrate of Figure 3A. Figure 4A is a scanning electron microscope image showing an enlarged view of the first metal body placed in the through hole of the ceramic sintered substrate according to the embodiment. Figure 4B is a scanning electron microscope image showing an enlarged view of the first metal body placed in the through hole of the ceramic sintered substrate according to the embodiment. Figure 7 is a schematic cross-sectional view showing the light-emitting device according to the embodiment. Figure 3A shows the state of the ceramic sintered substrate before sintering. Figure 4A shows the state inside the through hole, and Figure 4B shows the state near the interface between the through hole and the ceramic substrate 1.

[0014] The ceramic sintered substrate 10 comprises a ceramic substrate 1 having through holes 2 and a first metal body 3a disposed within the through holes 2. The first metal body 3a contains a plurality of metal powders 4a, a second metal 4b, and a metal compound 5. Here, "a plurality of metal powders 4a" does not mean that there are metal powders with clear interfaces, but rather that, in a cross-sectional view of the first metal body 3a, it can be observed that multiple objects that appear to be metal powders are aggregated based on the presence of voids and the state of the metal components. In other words, it does not mean that the metal powders are completely melted and no interfaces exist. If there is an object that appears to be a single metal powder due to the presence of reactants 5b of the metal compound 5 on the surface and grain boundaries of the metal powder 4a, it may be counted as a single metal powder 4a even if a part of it is bonded to other metal powders. The metal powder 4a has a higher melting point than the second metal 4b and is dispersed within the continuous second metal 4b. The ceramic substrate 1 has a reaction layer 5a of metal compound 5 on the inner wall of the through hole 2, and a reaction product 5b of metal compound 5 on the surface and grain boundaries of the metal powder 4a. However, the first metal body may be referred to as the first metal paste before firing, and the conductor may be referred to as the conductive paste before firing. Although the state after firing differs from that of the raw materials, for the sake of explanation, the raw material name may be used when referring to the fired product. The properties of the ceramic substrate differ before and after firing, but it will be described as a ceramic substrate. The following describes the various components of the ceramic sintered substrate 10.

[0015] (Ceramic substrate) The ceramic substrate 1 is a plate-shaped member that forms the base of the ceramic sintered substrate 10. The planar shape of the ceramic substrate 1 is, for example, rectangular. However, the planar shape of the ceramic substrate 1 is not particularly limited. The ceramic substrate 1 preferably contains at least one selected from silicon nitride, aluminum nitride, and boron nitride. While nitride-based ceramics such as silicon nitride, aluminum nitride, and boron nitride are preferred for the ceramic substrate 1, oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide may also be used. Furthermore, the ceramic substrate 1 may also be made of silicon carbide, mullite, borosilicate glass, etc.

[0016] The ceramic substrate 1 has through holes 2 formed at predetermined positions in the thickness direction, and a first metal body 3a is placed inside the through holes 2. A conductor 8a is then placed on the ceramic substrate 1 such that at least a portion of the first metal body 3a is in contact with it. In this case, the conductor 8a is placed on both the front and back surfaces of the ceramic substrate 1 so as to be in contact with at least a portion of the first metal body 3a located in the through holes 2. The conductor 8a is used as wiring, wiring pads, or external connection electrodes for electrical connection with the light-emitting element 20.

[0017] Furthermore, the through-holes 2 in the ceramic substrate 1 are via holes for electrically connecting the element electrodes 24 of the light-emitting element 20 to the outside of the ceramic substrate 1 via the first metal body 3a placed inside. The through-holes 2 are formed by mechanical processing such as drilling or laser processing on the sintered ceramic substrate or the green sheet of the ceramic substrate before firing, or by chemical processing such as etching on the sintered ceramic substrate 1. When the through-holes 2 are cut horizontally to the ceramic substrate 1, their shape is preferably approximately circular or circular. The diameter of the through-holes 2 is preferably 0.05 mm or more and 0.5 mm or less. If the through-holes 2 are 0.05 mm or more, it becomes easier to accurately position the first metal body 3a. If the through-holes 2 are 0.5 mm or less, it is possible to achieve an appropriate filling amount while maintaining high strength and low electrical resistance.

[0018] (1st metal body) The first metal body 3a is placed in the through-hole 2 of the ceramic substrate 1. The first metal body 3a is a component that makes an electrical connection with the light-emitting element 20, either alone or together with the conductor 8a. As an example, the first metal body 3a includes metal powder 4a, a second metal 4b, and a metal compound 5, with a reaction layer 5a of the metal compound 5 formed on the inner surface defining the through-hole 2, and a reactant 5b of the metal compound 5 formed on the surface or grain boundary of the second metal 4b placed around the metal powder 4a. However, the first metal paste 3 is described here as including an inorganic filler 7 other than metal.

[0019] As an example, the first metal paste 3, in its pre-sintering state, contains 63% to 85% by mass of the first metal powder, which has metal powder 4a and a coated metal member 40b that becomes the second metal 4b; 1% to 15% by mass of the activated metal powder; and 5% to 15% by mass of the organic binder 6, which is a solvent. After firing, the first metal paste 3 becomes the first metal body. After firing, the coated metal member 40b becomes the second metal 4b. After firing, the activated metal powder 50 becomes the metal compound 5. The first metal body 3a contains 60% to 80% by mass of metal powder 4a, 3% to 25% by mass of the second metal 4b, and 1% to 15% by mass of the reactant 5b of the metal compound 5. The reaction layer 5a of the metal compound 5 is segregated on the inner surface defining the through hole 2. In the first metal body 3a, the inorganic filler 7 is dispersed.

[0020] The metal powder 4a is the metal powder that forms the core of the first metal powder 4 when it is arranged as the first metal paste 3. The median diameter of the metal powder 4a is preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 40 μm or less. If the metal powder 4a is 1 μm or larger, it becomes easier to coat the second metal, which is the coating metal member 40b before firing. Also, if the metal powder 4a is 50 μm or smaller, it becomes easier to arrange in relation to the size of the through hole 2. In its pre-sintering state, the metal powder 4a is covered by the coating metal member 40b, which has a lower melting point than the metal powder 4a. The metal powder 4a is dispersed in the first metal paste together with the activated metal powder 50, the organic binder 6, and the inorganic filler 7. After firing, the metal powder 4a is dispersed in the second metal 4b.

[0021] In other words, the coating metal members 40b that covered the metal powder 4a are melted by firing, and the coating metal members 40b surround each other, becoming partially continuous. The metal powder 4a is held in a dispersed state within these molten coating metal members 40b. This is because the molten coating metal members 40b have high viscosity even in small amounts, so the metal powder 4a hardly settles or floats up. In addition, the metal powder 4a maintains its particle size state by being fired in an unmelted state.

[0022] In other words, when the metal powder 4a is heated above its melting point, it melts and becomes liquid. However, since the heating temperature here is below the melting point of the metal powder 4a, the metal powder 4a itself does not melt and become liquid. Because the metal powder 4a does not melt and become liquid, there is no significant flow in the first metal paste 3. This reduces the likelihood of the surface of the first metal paste 3 shrinking and becoming significantly concave. However, even at temperatures below the melting point, the metal powder 4a reacts with the coated metal member 40b, causing a portion of the surface of the metal powder 4a to soften and be arranged in contact with or mixed with other metal powders 4a or the second metal 4b. In this case, there may or may not be an interface between the metal powder 4a and the second metal 4b. Since it is possible to have no interface between the metal powder 4a and the second metal 4b in this way, the electrical resistance can be reduced and the electrical and thermal conductivity can be increased.

[0023] Furthermore, because the first metal powder 4 in the first metal paste 3 is densely arranged, even after firing, there are few voids and low stress, resulting in a highly reliable state for thermal cycling characteristics and other properties. Preferably, this metal powder 4a contains at least one selected from, for example, Cu, Cr, and Ni. The metal powder 4a also includes alloys mainly composed of Cu, Cr, and Ni. Preferably, the metal powder 4a is Cu or a Cu alloy. Also, preferably, the melting point of the metal powder 4a is between 1050°C and 2500°C. If the melting point of the metal powder 4a is 1050°C or higher, the difference in melting point with that of the second metal 4b or metal compound 5 described later becomes large, and the dispersion state can be improved. Also, if the melting point of the metal powder 4a is 2500°C or lower, the adverse effects on other components can be reduced.

[0024] The second metal 4b is positioned to surround at least a portion or all of the metal powder 4a. The second metal 4b has a lower melting point than the metal powder 4a and preferably contains at least one selected from, for example, Ag, Al, Zn, Sn, and Ag-Cu alloy. Ag and Ag-Cu alloy are particularly preferred. Since the melting point of Ag is 962°C and the melting point of Ag-Cu alloy is around 780°C, the difference in melting points with the metal powder 4a can be reduced. In its pre-molten state, the second metal 4b is positioned around the metal powder 4a such that it has a thickness of 3% to 30% of the diameter or major axis of the metal powder 4a, and after firing, it melts and is positioned around the metal powder 4a.

[0025] In other words, because the metal powder 4a is coated with a predetermined thickness, the metal powder 4a particles do not come into contact with or separate from each other more than necessary even after firing. This moderate dispersion of the metal powder 4a also helps to suppress uneven heat distribution within the through-holes. Furthermore, the melting point of the second metal 4b is preferably 200°C to 1000°C, more preferably 500°C to 980°C, and particularly preferably 750°C to 970°C. This is because a melting point of 200°C or higher allows the second metal 4b to withstand the reflow temperature during the manufacture of the light-emitting device. Also, if the melting point of the second metal 4b is 1000°C or lower, there is a predetermined difference between it and the melting point of the metal powder 4a, so the metal powder 4a does not melt and the dispersion state of the metal powder 4a can be improved. The difference in melting points between the second metal 4b and the metal powder 4a is preferably at least 50°C, and more preferably 100°C or higher. Although the second metal 4b is made of almost the same material as the coated metal member 40b, the thickness of the coated metal member 40b is extremely thin, so the coated metal member 40b may melt at a firing temperature significantly lower than the melting point of the second metal 4b.

[0026] The thickness of the second metal 4b on the coating metal member 40b before melting is preferably constant and covers the entire circumference of the metal powder 4a. The coating metal member 40b preferably has a thickness of 3% to 30% of the diameter or major axis of the metal powder 4a. Furthermore, if the coating metal member 40b before melting the second metal 4b covers a part of the metal powder 4a, it is preferable that the thinner portion is 3% or more of the diameter or major axis of the metal powder 4a, and the thicker portion is 30% or less. If the ceramic substrate 1 contains nitrogen, after firing, a reaction product 5b of the metal compound 5 is formed on the surface of the metal powder 4a or in the second metal 4b. The case where the ceramic substrate 1 contains nitrogen is, for example, when at least one selected from silicon nitride, aluminum nitride, and boron nitride is used. In addition, the second metal 4b, together with the components of the metal compound 5, forms a reaction layer 5a of the metal compound 5 on the inner surface that defines the through hole 2.

[0027] The metal compound 5 may also be placed between the metal powders 4a. The activated metal powder 50 is converted to metal compound 5, at least partially or entirely, by firing. The activated metal powder 50 is dispersed in the first metal paste 3, and the metal compound 5 after firing is also dispersed in the first metal body 3a. For example, titanium hydride (TiH2) is used as the activated metal powder 50. Titanium hydride releases hydrogen upon firing to become metallic titanium, and then the titanium is oxidized or nitrided to become titanium oxide or titanium nitride, etc. If the ceramic substrate 1 contains nitrogen, the activated metal powder 50 contained in the first metal paste 3 reacts with the nitrogen in the ceramic substrate 1, and a reaction layer 5a of the metal compound 5 is formed at the interface between the first metal paste 3 and the ceramic substrate 1. The reactants 5b of the metal compound 5 are arranged so as to be continuous or at the grain boundaries between the metal powders 4a. The metal compound 5 is arranged in a state of direct contact with the metal powder 4a, in contact with or surrounding the second metal 4b, or surrounding the inorganic filler 7. Furthermore, as described above, the metal compound 5, together with the components of the second metal 4b, forms a reaction layer 5a on part or all of the inner surface that partitions the through hole 2, thereby improving the adhesion strength between the first metal body 3a and the ceramic substrate 1.

[0028] Furthermore, the melting points of the second metal 4b and the metal compound 5 are lower than the melting point of the metal powder 4a. Therefore, even when the metal powder 4a is fired while placed in the through hole 2 as the first metal paste 3, causing the coated metal member 40b to melt and the activated metal powder 50 to react, the metal powder 4a remains dispersed. In addition, the second metal 4b melted from the coated metal member 40b is continuously arranged within the through hole 2. Here, "the second metal 4b is continuously arranged within the through hole 2" does not mean that it is physically connected from the top to the bottom of the through hole 2, nor is it unevenly distributed to either the top or bottom of the through hole 2, but rather that it is continuously arranged from the top to the bottom of the through hole 2, scattered among multiple metal powders 4a. In other words, generally, when metal melts and becomes liquid, it tends to flow and become unevenly distributed. However, here, by arranging the covering metal member 40b to cover the metal powder 4a and firing it at a predetermined firing temperature, the flow associated with the melting of the covering metal member 40b is reduced, allowing it to be dispersed without uneven distribution from the upper end to the lower end within the through hole 2. The metal compound 5 reacted from the activated metal powder 50 is dispersed as reactant 5b within the first metal body 3a, and the reaction layer 5a is arranged on the inner surface defining the through hole 2. Even if there is a difference in specific gravity between the metal powder 4a, the second metal 4b, and the metal compound 5, the dispersed state can be maintained without settling or floating.

[0029] The activated metal powder 50 is preferably one or more materials selected from, for example, TiH2, CeH2, ZrH2, LaH2, and MgH2. By firing this activated metal powder 50, all or part of the hydrogen is removed and reacts with nitrogen, oxygen, carbon, etc. contained in the ceramic substrate 1, inorganic filler 7, etc., and changes into nitride metals, oxide metals, carbide metals, etc. These changed materials are metal compounds. It is particularly preferable to use TiH2 for the activated metal powder 50, as the inclusion of TiH2 reacts with nitrogen contained in the ceramic substrate 1, etc., and forms a reaction layer 5a such as TiH2 at the interface with the ceramic sintered substrate 10. This improves the adhesion between the first metal body 3a, which is a conductive via, and the ceramic substrate 1, and the first metal body 3a adheres firmly to the through hole 2.

[0030] The inorganic filler 7 is dispersed within the first metal paste 3 to reduce crack formation. Examples of inorganic filler 7 include ceramic fillers, metal fillers, and glass fillers. Specifically, the inorganic filler 7 may be aluminum oxide, silicon oxide, etc. The inorganic filler 7 is included in a quantity that does not interfere with the effects of other ingredients.

[0031] The organic binder 6 is a component contained in the first metal paste 3 before firing. After firing, the organic binder 6 evaporates and does not remain in the first metal paste 3. The organic binder 6 may, for example, be a solvent or resin material commonly used as a via material.

[0032] The conductor 8a is a conductive member that forms wiring, wiring pads, or external connection electrodes of a predetermined wiring pattern. The conductor 8a may be formed by firing a conductive paste 8. The conductive paste 8 is arranged so as to be in contact with at least a part of the first metal paste 3 or the first metal body 3a. The thickness of the conductive paste 8 is preferably, for example, 12 μm or more and 35 μm or less. The wiring or connection pads of the conductive paste 8 can be formed, for example, by etching or printing. The conductive paste 8 is arranged as wiring etc. on the first surface of the ceramic substrate 1, and also as wiring etc. on the second surface opposite the first surface. The conductive paste 8 is formed in a rectangular, circular, linear, etc. shape in plan view, and is arranged on the first surface of the ceramic substrate 1 at a distance from each other, and also at a distance from each other on the second surface. The size of the conductive paste 8 on the first surface of the ceramic substrate 1 and the size of the conductive paste 8 on the second surface are, for example, made to differ so that the area on the first surface is larger than the area on the second surface, but they may be the same size. For example, the conductive paste 8 is shown as a rectangle in a top view so as to be in contact with the entire circular first metal paste, but its shape and arrangement are arbitrary and not limited.

[0033] The conductive paste 8 preferably uses the same components as the first metal paste 3, for example. The material of the conductor 8a may be copper foil as the metal component. Furthermore, the material of the conductive paste 8 may be a mixture of a resin binder with a powder of a single element or an alloy or mixed powder of a metal such as gold, silver, copper, platinum, or aluminum. The resin binder may be a thermosetting resin such as epoxy resin or silicone resin. It is also preferable that the conductive paste 8 contains a reducing agent such as an organic acid. This makes it possible to reduce the electrical resistance in the connection with the light-emitting element 20.

[0034] In the ceramic sintered substrate 10 having the above configuration, the first metal paste 3 is firmly bonded to the inner surface defining the through-hole 2 of the ceramic substrate 1, thus providing high reliability and ensuring reliable electrical connection with the light-emitting element. Furthermore, the number of through-holes 2 in the ceramic substrate 1 may be two or more, and their shape is not limited to circular; it may also be elliptical, rectangular, or other shapes. Furthermore, the shape of the conductor 8a may be square, rectangular, trapezoidal, or include curved portions. Alternatively, the conductor 8a may be omitted, and the light-emitting element 20 may be directly connected to a part of the first metal body 3a.

[0035] [Method for manufacturing ceramic sintered substrates] Next, a method for manufacturing a ceramic sintered substrate according to the embodiment will be described with reference to Figures 5 to 6C. Figure 5 is a flowchart illustrating a method for manufacturing a ceramic sintered substrate according to the embodiment. Figure 6A is a schematic cross-sectional view showing a prepared ceramic substrate in the method for manufacturing a ceramic sintered substrate according to the embodiment. Figure 6B is a schematic cross-sectional view showing a state in which the first metal paste is placed in the through-holes in the method for manufacturing a ceramic sintered substrate according to the embodiment. Figure 6C is a schematic cross-sectional view showing a state in which the conductive paste is placed in the method for manufacturing a ceramic sintered substrate according to the embodiment.

[0036] The method for manufacturing a ceramic sintered substrate S10 includes preparing a ceramic substrate with through holes formed before firing S11, placing a first metal paste in the through holes S12, and firing the ceramic substrate with the first metal paste in place S14. In placing the first metal paste S12, the first metal paste includes a plurality of first metal powders and a plurality of active metal powders, and the first metal powder has a core metal powder and a covering metal member which has a lower melting point than the metal powder and covers at least a part of the metal powder. In firing the ceramic substrate S14, the firing temperature is 700°C or higher and below the melting point of the metal powder. As an example, the method for manufacturing a ceramic sintered substrate S10 will be described as performing a conductive paste S13 on the ceramic substrate after placing the first metal paste S12 and before firing the ceramic substrate S14, such that at least a part of it is in contact with the first metal paste.

[0037] (Prepare a ceramic substrate) Step S11 (hereinafter referred to as step S11) involves preparing a ceramic substrate, for example, by preparing a flat substrate. In step S11, the prepared ceramic substrate 1 has through-holes 2 formed in it by laser processing or the like, corresponding to the number of connection parts for the element electrodes 24 of the light-emitting element 20 described later. For example, when one light-emitting element 20 is to be placed on the ceramic substrate 1, two through-holes 2 are formed on it. The ceramic substrate 1 may also be prepared with a number of through-holes 2 formed that corresponds to the size of the area for placing multiple light-emitting elements 20 and the number of element electrodes 24, or it may be prepared by cutting it to a size that accommodates a predetermined number of light-emitting elements 20.

[0038] (Place the first metal paste) Step S12, which involves placing the first metal paste, is to place the first metal paste into the through-holes 2 formed in the ceramic substrate 1. In this step S12, the first metal paste 3 is placed into the through-holes 2, for example, by screen printing or injection using a nozzle. The first metal powder 4 has a core metal powder 4a and a covering metal member 40b that covers the metal powder 4a.

[0039] In step S12, when placing the first metal paste 3 into the through hole 2, it is preferable to place the first metal paste into the through hole 2 from the first surface, which is one side of the ceramic substrate 1, using a squeegee, for example, which is a tool used in screen printing, and then to place the first metal paste into the through hole 2 from the second surface, which is the other side of the ceramic substrate 1, using a squeegee in the same manner as the first surface.

[0040] Next, the conductive paste 8 is placed in step S13 (hereinafter referred to as step S13). In step S13, the conductive paste 8 is placed on the ceramic substrate 1 so that at least a portion of it is in contact with the first metal paste 3 placed in the through hole 2. In step S13, the conductive paste 8 is placed so that it is in contact with the entire surface of the first metal paste 3 that is exposed from the through hole 2 of the ceramic substrate 1. As an example, the conductive paste 8 is placed in a rectangular shape in a total of four locations: two on the first surface of the ceramic substrate 1 and two on the second surface of the ceramic substrate 1. The conductive paste 8 then forms rectangular wiring or wiring pads on the first and second surfaces of the ceramic substrate 1 via a mask using screen printing, metal mask printing, etc.

[0041] Furthermore, the first metal paste 3 and conductive paste 8 used in steps S12 and S13 are fluid and can be freely placed in through holes 2 of any shape, and can also be placed by applying them to any shape and thickness and then curing them.

[0042] Next, the ceramic substrate is fired in step S14 (hereinafter referred to as step S14). In step S14, the firing temperature is 700°C or higher and below the melting point of the metal powder. When performing the firing in step S14, the firing atmosphere is an Ar atmosphere of 99.9% or higher or 10 -5 A vacuum atmosphere of Pa or less is preferable. Furthermore, in this step S14, the firing temperature is preferably 700°C to 1000°C, more preferably 700°C to 980°C, and particularly preferably 750°C to 970°C.

[0043] Furthermore, the ceramic sintered substrate 10 can be manufactured by step 14. As shown in Figures 3B and 4, when the state of the first metal paste 3 is observed after firing, for example, the copper powder, which is the metal powder 4a, maintains the same state as before firing, dispersed in the Ag-Cu alloy, which is the continuous second metal 4b. This is because, as described above, the firing temperature is adjusted to be below a predetermined temperature, so that the metal powder 4a does not melt, and the metal compound 5, which is formed when the molten second metal 4b and the activated metal powder 50 react with the coated metal member 40b, is placed between the metal powders 4a. In addition, after firing, the metal compound 5 formed by the reaction of the activated metal powder 50 forms a reaction product 5b of the metal compound 5 on the surface of the coated metal member 40b before melting, and a reaction layer 5a of the metal compound 5 is formed on the inner surface defining the through-hole 2 of the ceramic substrate 1. Thus, after firing, the reaction layer 5a of the metal compound 5 is formed by the first metal paste 3, resulting in a strong bond between the first metal paste 3 and the through-hole 2. Therefore, in the electrical connection made via the first metal body 3a, the ceramic sintered substrate 10 exhibits stable conductivity because the dispersion state of the metal powder 4a is relatively uniform. Furthermore, because the reaction layer 5a of the metal compound 5 is formed, the bonding strength between the first metal paste and the inner surface defining the through-hole 2 is high, resulting in a highly reliable structure.

[0044] [Light-emitting device] Next, the light-emitting device 100 according to the embodiment will be described with reference to Figure 7. The light-emitting device 100 is a device that emits light by arranging light-emitting elements 20 on a ceramic sintered substrate 10. In the drawing, there is one light-emitting element 20, but there may be multiple light-emitting elements 20, and their arrangement is not particularly limited, such as being in a single row.

[0045] The light-emitting device 100 comprises a ceramic sintered substrate 10, as previously described, and a light-emitting element 20 electrically connected to a conductor 8a that forms wiring on the ceramic sintered substrate 10. The light-emitting device 100 also includes, as an example, a light-reflecting member 30 covering the sides of the light-emitting element 20 and the ceramic sintered substrate 10. Furthermore, the ceramic sintered substrate 10 can be used to form wiring in various patterns depending on the application.

[0046] (light-emitting element) The light-emitting element 20 includes a pair of element electrodes 24, a light-transmitting member 23 disposed on the light extraction surface side of the light-emitting element 20, an element substrate 22, and a semiconductor laminate 21. The light-emitting element 20, as an example, has a semiconductor laminate 21 on an element substrate 22. In this embodiment, a light-transmitting member 23 is arranged on the upper side of the element substrate 22, which is the light extraction surface, and the semiconductor laminate 21 is provided on the lower side of the element substrate 22. The semiconductor laminate 21 has a pair of element electrodes 24. As the semiconductor laminate 21, any composition can be used depending on the desired emission wavelength, but for example, a nitride semiconductor (In) capable of emitting blue or green light can be used. X Al Y Ga 1-X-Y Materials such as N (0 ≤ X, 0 ≤ Y, X + Y ≤ 1), GaP, or GaAlAs or AlInGaP capable of emitting red light can be used. The size and shape of the light-emitting element 20 can be appropriately selected depending on the purpose of use. As an example, the element substrate 22 can be a sapphire substrate or a silicon substrate.

[0047] The light-transmissive member 23 is made of, for example, a light-transmissive resin material, and an epoxy resin, a silicone resin, or a resin obtained by mixing these can be used. The light-transmissive member 23 may contain a phosphor, and for example, by containing a phosphor that absorbs blue light from the light-emitting element 20 and emits yellow light, white light can be emitted. Further, the light-transmissive member 23 may contain a plurality of types of phosphors. For example, by containing a phosphor that absorbs blue light from the semiconductor laminate 21 and emits green light and a phosphor that emits red light, white light can also be emitted from the light-emitting element 20.

[0048] Examples of such phosphors include yttrium aluminum garnet-based phosphors (e.g., Y3(Al,Ga)5O 12 :Ce), lutetium aluminum garnet-based phosphors (e.g., Lu3(Al,Ga)5O 12 :Ce), terbium aluminum garnet-based phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), β-sialon phosphors (e.g., (Si,Al)3(O,N)4:Eu), α-sialon phosphors (e.g., Mz(Si,Al) 12 (O,N) 16 (where 0 < z ≦ 2 and M is Li, Mg, Ca, Y, and lanthanide elements excluding La and Ce)), nitride-based phosphors such as CASN-based phosphors (e.g., CaAlSiN3:Eu) or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), fluoride-based phosphors such as KSF-based phosphors (e.g., K2SiF6:Mn), KSAF-based phosphors (e.g., K2(Si,Al)F6:Mn), or MGF-based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn), or quantum dot phosphors such as perovskite and chalcopite can be used.

[0049] The element electrode 24 is connected to the conductor 8a of the ceramic sintered substrate 10 via a bonding member 11 by a metal bump 12. Here, the conductor 8a is preferably surface-treated by plating in the order of Ni / Pd / Au. One of the element electrodes 24 is a p electrode, and it is positioned at a distance that prevents electrical short-circuiting with the other n electrode. As an example, the element electrode 24 is configured with one p electrode and one n electrode, but it is also acceptable to have two p electrodes and one n electrode on one side.

[0050] The metal bumps 12 electrically connect the element electrodes 24 and the conductor 8a. The metal bumps 12 may be positioned on either the element electrode 24 side or the conductor 8a side. Furthermore, the shape, size, and number of the metal bumps 12 can all be appropriately set as long as they can be positioned within the range of the element electrodes 24. The size of the metal bumps 12 can be appropriately adjusted depending on the size of the semiconductor laminate, the required light emission output of the light-emitting element, etc. For example, a diameter of several tens of micrometers to several hundred micrometers is possible.

[0051] The metal bumps 12 can be formed from, for example, Au, Ag, Cu, Al, Sn, Pt, Zn, Ni, or alloys thereof, and can be formed, for example, by stud bumps known in the art. Stud bumps can be formed by a stud bump bonder, wire bonding apparatus, etc. Alternatively, the metal bumps 12 may be formed by methods known in the art, such as electroplating, electroless plating, vapor deposition, sputtering, etc.

[0052] As an example, the metal bumps 12 are joined here via a joining member 11. Examples of the joining member 11 used here include solders such as tin-bismuth, tin-copper, tin-silver, and gold-tin; eutectic alloys such as alloys mainly composed of Au and Sn, alloys mainly composed of Au and Si, and alloys mainly composed of Au and Ge; paste materials such as silver, gold, and palladium; anisotropic conductive materials such as ACP and ACF; brazing materials of low-melting-point metals; conductive adhesives and conductive composite adhesives that combine these materials.

[0053] (Light-reflecting material) The light-reflecting member 30 is a member that has light-reflecting properties. The light-reflecting member 30 is positioned to cover the first surface of the ceramic sintered substrate 10 and to cover the side surface of the light-emitting element 20. Furthermore, the light-reflecting member 30 is positioned to expose the light extraction surface of the light-emitting element 20 and to be coplanar with the light-transmitting member 23 of the light-emitting element 20. As an example, the light-reflecting member 30 is also positioned between the lower surface of the light-emitting element 20 and the first surface of the ceramic sintered substrate 10.

[0054] The light-reflecting member 30 preferably has a high reflectivity in order to effectively utilize the light from the light-emitting element 20. The light-reflecting member 30 is preferably white. The reflectivity of the light-reflecting member 30 is preferably 90% or more, and more preferably 94% or more, at the wavelength of light emitted by the light-emitting element 20. The light-reflecting member 30 can be made of a thermoplastic resin such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyester resin, or a thermosetting resin such as epoxy resin or silicone resin. As a light-diffusing material, known materials such as titanium dioxide, silica, alumina, zinc oxide, or glass can be used.

[0055] The light-emitting device 100 having the above configuration includes a first metal body 3a in the ceramic sintered substrate 10, which increases the bonding strength between the first metal body 3a and the ceramic substrate 1, thereby improving reliability. The light-emitting device 100 uses one light-emitting element 20 as a unit to control brightness and on / off states, but the number of light-emitting elements 20 included in one unit may be one or multiple. For example, one unit can consist of four light-emitting elements 20 arranged in 1 row and 4 columns, or 2 rows and 2 columns, or nine light-emitting elements 20 arranged in 3 rows and 3 columns.

[0056] [Manufacturing method for light-emitting devices] Next, the method for manufacturing the light-emitting device according to the embodiment will be described with reference to Figures 8 to 9D. Figure 8 is a flowchart illustrating the method for manufacturing the light-emitting device according to the embodiment. Figure 9A is a schematic cross-sectional view showing the prepared ceramic sintered substrate in the method for manufacturing the light-emitting device according to the embodiment. Figure 9B is a schematic cross-sectional view showing the state in which the components are arranged on the ceramic sintered substrate. Figure 9C is a schematic cross-sectional view showing the state in which the light-emitting element is arranged in the method for manufacturing the light-emitting device according to the embodiment. Figure 9D is a schematic cross-sectional view showing the state in which the light-reflecting member is arranged in the method for manufacturing the light-emitting device according to the embodiment.

[0057] The method for manufacturing the light-emitting device S20 includes preparing a ceramic sintered substrate manufactured by the ceramic sintered substrate manufacturing method S10 described above, S21, and arranging a light-emitting element on the ceramic sintered substrate, wherein in arranging the light-emitting element S22, the first metal member arranged in the through hole and the light-emitting element are electrically connected directly or indirectly. The method for arranging the light-emitting element S22 may also include arranging a light-reflecting member S23. Furthermore, in arranging the light-emitting element S22, the element electrode 24 may be directly or indirectly connected to a conductor 8a that is in contact with at least a portion of the first metal body 3a.

[0058] (Prepare a ceramic sintered substrate.) Step S21 (hereinafter referred to as step S21) means preparing a ceramic sintered substrate 10 manufactured by the ceramic sintered substrate manufacturing method S10 described above. The ceramic sintered substrate 10 has four conductive members 8a connected to first metal bodies 3a placed in through holes 2 on its first and second surfaces. The shape, size, and spacing of the conductive members 8a can be adjusted to match the element electrodes 24 of the light-emitting element 20. The ceramic sintered substrate 10 has multiple areas for placing the light-emitting elements 20, and after placing the light-reflecting members 30 described later, it may be made into pieces large enough to separate into individual light-emitting devices 100, or it may be made into pieces large enough for one light-emitting device 100.

[0059] (Placing light-emitting elements) Step S22, which involves arranging the light-emitting element, is the process of placing the light-emitting element 20 on the ceramic sintered substrate 10. In this step S22, the element electrodes 24 of the light-emitting element 20 are connected using metal bumps 12 via a bonding member 11 placed on the conductor 8a. As the conductive bonding member 11, for example, bumps made of gold, silver, or copper, a conductive paste material which is a mixture of metal powder such as gold, silver, copper, platinum, or aluminum and a resin binder, or a tin-silver-copper (SAC) or tin-bismuth (SnBi) solder can be used. The light-emitting element 20 is placed with the translucent member 23 already connected to the element substrate 22. When bonding the translucent member 23 to the element substrate 22, a translucent bonding material is used.

[0060] (By placing light-reflecting elements) The process of arranging the light-reflecting member S23 (hereinafter referred to as process S23) involves arranging the light-reflecting member 30 so as to cover the first surface, which is the upper surface of the ceramic sintered substrate 10, and also to cover the side surface of the light-emitting element 20. In this process S23, the light-reflecting member 30 is placed on the ceramic sintered substrate 10 so as to surround the light-emitting element 20 and expose the upper surface of the translucent member 23, which is the light-extracting surface of the light-emitting element 20. The light-reflecting member 30 is arranged so as to form a rectangle in plan view.

[0061] In the manufacturing method S20 of the light-emitting device, individualization is performed as needed after the work in process S23 is completed. One unit of the light-emitting device 100 is predetermined by the number of light-emitting elements 20 used. Therefore, if multiple light-emitting devices 100 are manufactured together, individualization is performed. When individualization is performed, multiple light-emitting devices 100 are produced by cutting in a grid pattern. As for the cutting method, for example, a disc-shaped rotating blade, an ultrasonic cutter, laser irradiation, or a blade can be used.

[0062] The manufacturing method S20 for the light-emitting device having the above configuration improves reliability by increasing the bonding strength of the first metal paste 3 placed in the through-holes 2 of the ceramic substrate 1 using the manufacturing method S10 for the ceramic sintered substrate, thereby enabling stable control of the light-emitting element 20.

[0063] (Examples of application) As shown in Figures 10A and 10B, the light-emitting device 100 may be configured as a light-emitting module 100A with multiple devices (11 in the drawings) arranged in a single row. The configuration when using the light-emitting module 100A will now be described. Figure 10A is a perspective view showing an example of an application of the light-emitting device. Figure 10B is a cross-sectional view showing a cross-section with a portion of Figure 10A omitted. The light-emitting module 100A comprises 11 light-emitting devices 100 in a row, has a frame 140 on the outside of the light-reflecting member 30, and the module substrate 150 is connected to the conductor 8a below the ceramic sintered substrate 10.

[0064] The frame 140 is a member that surrounds the light-reflecting members 30 that cover the multiple light-emitting devices 100. The frame 140 is formed in a rectangular ring shape, for example, which is rectangular in plan view, and is arranged to surround the light-reflecting members 30. The frame 140 can be formed using a frame-shaped member made of metal, alloy, or ceramic. Examples of metals include Fe, Cu, Ni, Al, Ag, Au, Al, Pt, Ti, W, and Pd. Examples of alloys include alloys containing at least one of Fe, Cu, Ni, Al, Ag, Au, Al, Pt, Ti, W, and Pd. Alternatively, a resin material may be used for the frame 140. In this case, the above-mentioned metal, alloy, or ceramic member may be embedded in the frame 140 formed of resin material, or part of the frame 140 may be made of resin material and the other part of it may be made of metal, alloy, or ceramic member.

[0065] The module substrate 150 is a component on which the light-emitting device 100 is mounted, and it electrically connects the light-emitting device 100 to the outside. The module substrate 150 is formed in a substantially rectangular shape, for example, in a plan view. The module substrate 150 comprises a substrate portion 160 and a wiring board portion 170. As the material for the substrate portion 160, it is preferable to use an insulating material, and more preferably a material that does not easily transmit light emitted from the light-emitting element 20 or ambient light. For example, ceramics such as alumina, aluminum nitride, and mullite, thermoplastic resins such as polyamide, polyphthalamide, polyphenylene sulfide, or liquid crystal polymer, or resins such as epoxy resin, silicone resin, modified epoxy resin, urethane resin, or phenolic resin can be used. Among these, it is preferable to use ceramics, which have excellent heat dissipation properties.

[0066] Furthermore, the wiring board portion 170 is formed on the substrate portion 160 at a position facing the conductor 8a below the light-emitting device 100. Examples of materials for the wiring board portion 170 include those exemplified as materials used for the first metal body 3a and the conductor 8a. The module substrate 150 is joined to the frame 140 via a conductive adhesive 151, and is arranged so that the conductor 8a and the wiring board portion 170 are joined. For the conductive adhesive 151, for example, eutectic solder, conductive paste, bumps, etc., may be used. Furthermore, in the light-emitting device 100, protective elements 125 are arranged in parallel with each light-emitting element 20 on the ceramic sintered substrate 10.

[0067] As the light-emitting module 100A is configured as described above, when it is driven, the following occurs. Specifically, current is supplied from an external power source to the light-emitting element 20 via the wiring board section 170, conductive paste, first metal paste, and element electrode 24, causing the light-emitting element 20 to emit light. The light emitted by the light-emitting element 20, if it travels upward, is taken out to the outside of the light-emitting device 100 via the light-transmitting member 23. The light traveling downward is reflected by the ceramic sintered substrate 10 and taken out to the outside of the light-emitting device 100 via the light-transmitting member 23. The light traveling between the light-emitting element 20 and the frame 140 is reflected by the light-reflecting member 30 and the frame 140 and taken out to the outside of the light-emitting device 100 via the light-transmitting member 23. The light traveling between the light-emitting elements 20 is reflected by the light-reflecting member 30 and taken out to the outside of the light-emitting device 100 via the light-transmitting member 23. In this case, by narrowing the distance between the light-transmitting members 23 (for example, to 0.2 mm or less), the optical system configuration can be made simpler and more compact, for example, when the light-emitting module 100A is used as a light source for a vehicle's headlight.

[0068] When manufacturing the light-emitting module 100A, the light-emitting devices 100 are arranged on a sheet material, a frame 140 is placed around them, and the light-reflecting members 30 are placed in the space enclosed by the frame 140 and the sheet material. Then, the light-emitting devices 100, supported by the frame 140 and the light-reflecting members 30, are placed on a module substrate 150 on which the wiring board portion 170 and conductive adhesive 151 are arranged, and the light-emitting module 100A is manufactured by electrically connecting the conductive paste 8 and the wiring board portion 170. Furthermore, the structure of the claims may include the following dependent relationships as shown in [Clause 1] to [Clause 24].

[0069] [Section 1] Prepare a ceramic substrate with through-holes formed before firing, The first metal paste is placed in the through hole, This includes firing the ceramic substrate on which the first metal paste is arranged, In arranging the first metal paste, the first metal paste comprises a plurality of first metal powders and a plurality of active metal powders, wherein the first metal powder has a core metal powder and a covering metal member having a lower melting point than the metal powder and covering at least a portion of the metal powder. A method for manufacturing a ceramic sintered substrate, wherein the firing temperature of the ceramic substrate is 700°C or higher and below the melting point of the metal powder. [Section 2] A method for manufacturing a ceramic sintered substrate according to item 1, wherein the metal powder comprises at least one selected from Cu, Cr, and Ni, in arranging the first metal paste. [Section 3] A method for manufacturing a ceramic sintered substrate according to claim 1 or 2, wherein the coating metal member, in arranging the first metal paste, comprises at least one selected from Ag, Al, Zn, Sn, and Ag-Cu alloy. [Section 4] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 3, wherein the coating metal member has a thickness of 3% or more and 30% or less with respect to the diameter or major axis of the metal powder, in which the first metal paste is arranged. [Section 5] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 4, wherein, in arranging the first metal paste, the median diameter of the metal powder is 1 μm or more and 50 μm or less. [Section 6] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 5, wherein the first metal paste is arranged, and the active metal powder comprises at least one selected from TiH2, CeH2, ZrH2, and MgH2. [Section 7] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 6, wherein, in arranging the first metal paste, the melting point of the metal powder is 1050°C or more and 2500°C or less. [Section 8] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 7, wherein, in arranging the first metal paste, the melting point of the coating metal member is 200°C or more and 1000°C or less. [Section 9] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 8, wherein the first metal paste is further comprising an organic binder. [Section 10] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 9, wherein the first metal paste further comprises a plurality of inorganic fillers other than metal. [Section 11] A method for manufacturing a ceramic sintered substrate according to any one of items 1 to 10, wherein the firing temperature for firing the ceramic substrate is 1000°C or less. [Section 12] A method for manufacturing a ceramic sintered substrate according to any one of items 1 to 11, wherein the firing temperature for firing the ceramic substrate is 950°C or lower. [Section 13] In firing the aforementioned ceramic substrate, the firing atmosphere is an Ar atmosphere of 99.9% or more or 10 -5 A method for manufacturing a ceramic sintered substrate according to any one of items 1 to 12, wherein the atmosphere is a vacuum of Pa or less. [Section 14] A method for manufacturing a ceramic sintered substrate according to any one of claims 1 to 13, wherein, after placing the first metal paste and before firing the ceramic substrate, a conductive paste is placed on the ceramic substrate such that at least a portion of it is in contact with the first metal paste. [Section 15] Prepare a ceramic sintered substrate manufactured by the method for manufacturing a ceramic sintered substrate described in any one of items 1 to 13, This includes arranging light-emitting elements on the ceramic sintered substrate, In preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, A method for manufacturing a light-emitting device, comprising directly or indirectly electrically connecting the first metal body arranged in the through-hole and the light-emitting element. [Section 16] Prepare a ceramic sintered substrate manufactured by the method for manufacturing a ceramic sintered substrate described in item 14, This includes arranging light-emitting elements on the ceramic sintered substrate, In preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, and the conductive paste becomes a conductor. A method for manufacturing a light-emitting device, comprising directly or indirectly electrically connecting the first metal body or the conductor arranged in the through-hole with the light-emitting element. [Section 17] A ceramic substrate having through holes, The system comprises a first metal body disposed within the through hole, The first metal body comprises a plurality of metal powders, a second metal, and a metal compound, wherein the metal powders have a higher melting point than the second metal and are dispersed within the continuous second metal. The ceramic substrate is a ceramic sintered substrate having a reaction layer of the metal compound on the inner wall of the through hole and reactants of the metal compound at the grain boundaries of the metal powder. [Section 18] The ceramic sintered substrate according to claim 17, wherein the metal powder comprises at least one selected from Cu, Cr, and Ni. [Section 19] The ceramic sintered substrate according to claim 17 or 18, wherein the second metal comprises at least one selected from Ag, Al, Zn, Sn, and Ag-Cu alloy. [Section 20] The ceramic substrate is a ceramic sintered substrate according to any one of claims 17 to 19, comprising at least one selected from silicon nitride, aluminum nitride, and boron nitride. [Section 21] The aforementioned metal compound comprises at least one element selected from Ti, Ce, Zr, and Mg, as described in any one of the ceramic sintered substrates in any one of the items 17 to 20. [Section 22] The ceramic sintered substrate according to any one of claims 17 to 21, wherein the median diameter of the metal powder is 1 μm or more and 50 μm or less. [Section 23] When the ceramic substrate is cut horizontally, the through-hole is circular. The ceramic sintered substrate according to any one of claims 17 to 22, wherein the diameter of the through hole is 0.05 mm or more and 0.5 mm or less. [Section 24] A light-emitting device comprising a ceramic sintered substrate according to any one of claims 17 to 23, and a light-emitting element electrically connected to the first metal body of the ceramic sintered substrate. [Industrial applicability]

[0070] The light-emitting device according to the embodiment of this disclosure can be used as a light source for a variable-beam headlamp. In addition, the light-emitting device according to the embodiment of this disclosure can be used as a backlight light source for liquid crystal displays, various lighting fixtures, large displays, various display devices such as advertisements and destination signs, and furthermore, image reading devices and projector devices in digital video cameras, facsimile machines, copiers, scanners, etc. [Explanation of symbols]

[0071] 1. Ceramic substrate 2 through holes 3. First Metal Paste 3a First metal body 4 First metal powder 4a metal powder 4b Second metal 40b Covered metal member 50 Active metal powder 5 Metal compounds 5a Metal compound reaction layer 5b Reactants of metal compounds 6 Organic Binders 7. Inorganic fillers 8. Conductive paste 8a Conductor 10. Ceramic sintered substrate 11 Joining members 12 Metal bumps 20 Light-emitting elements 21 Semiconductor Stack 22 Element substrate 23 Translucent material 24-element electrode 30 Light-reflecting member 100 Light-emitting devices

Claims

1. Prepare a ceramic substrate with through-holes formed before firing, The first metal paste is placed in the through hole, This includes firing the ceramic substrate on which the first metal paste is arranged, In arranging the first metal paste, the first metal paste comprises a plurality of first metal powders and a plurality of active metal powders, wherein the first metal powder has a core metal powder and a covering metal member having a lower melting point than the metal powder and covering at least a portion of the metal powder. In firing the ceramic substrate, the firing temperature is 700°C or higher and below the melting point of the metal powder. A method for manufacturing a ceramic sintered substrate, wherein, in arranging the first metal paste, the coating metal member includes at least one selected from Ag and Ag-Cu alloy.

2. A method for manufacturing a ceramic sintered substrate according to claim 1, wherein the metal powder comprises at least one selected from Cu, Cr, and Ni, in arranging the first metal paste.

3. A method for manufacturing a ceramic sintered substrate according to claim 1, wherein, in arranging the first metal paste, the coating metal member has a thickness of 3% or more and 30% or less with respect to the diameter or major axis of the metal powder.

4. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein, in arranging the first metal paste, the median diameter of the metal powder is 1 μm or more and 50 μm or less.

5. In arranging the first metal paste, the activated metal powder is TiH ２ CeH ２ , ZrH ２ MgH ２ A method for manufacturing a ceramic sintered substrate according to claim 1, comprising at least one selected from the above.

6. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein, in arranging the first metal paste, the melting point of the metal powder is 1050°C or higher and 2500°C or lower.

7. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein, in arranging the first metal paste, the melting point of the coating metal member is 750°C or higher and 980°C or lower.

8. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein the first metal paste further comprises an organic binder when the first metal paste is placed.

9. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein the first metal paste further comprises a plurality of inorganic fillers other than metal, in the arrangement of the first metal paste.

10. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein the firing temperature for firing the ceramic substrate is 1000°C or less.

11. The method for manufacturing a ceramic sintered substrate according to claim 1, wherein the firing temperature for firing the ceramic substrate is 950°C or lower.

12. In firing the aforementioned ceramic substrate, the firing atmosphere is an Ar atmosphere of 99.9% or more or 10 －５ A method for manufacturing a ceramic sintered substrate according to claim 1, wherein the atmosphere is a vacuum below Pa.

13. A method for manufacturing a ceramic sintered substrate according to claim 1, wherein, after arranging the first metal paste and before firing the ceramic substrate, a conductive paste is arranged on the ceramic substrate such that at least a portion of it is in contact with the first metal paste.

14. A ceramic sintered substrate is prepared by the method for manufacturing a ceramic sintered substrate described in any one of claims 1 to 12, This includes arranging light-emitting elements on the ceramic sintered substrate, In preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, A method for manufacturing a light-emitting device, comprising directly or indirectly electrically connecting the first metal body arranged in the through-hole and the light-emitting element.

15. A ceramic sintered substrate is prepared by the method for manufacturing a ceramic sintered substrate described in claim 13, This includes arranging light-emitting elements on the ceramic sintered substrate, In preparing the ceramic sintered substrate, the first metal paste becomes a first metal body by firing, and the conductive paste becomes a conductor. A method for manufacturing a light-emitting device, comprising directly or indirectly electrically connecting the first metal body or the conductor arranged in the through-hole with the light-emitting element.

16. A ceramic substrate having through holes, The system comprises a first metal body disposed within the through hole, The first metal body comprises a plurality of metal powders, a second metal, and a metal compound, wherein the metal powders have a higher melting point than the second metal and are dispersed within the continuous second metal. The ceramic substrate has a reaction layer of the metal compound on the inner wall of the through hole, and has reactants of the metal compound at the grain boundaries of the metal powder. The second metal comprises at least one selected from Ag and Ag-Cu alloys, and is a ceramic sintered substrate.

17. The ceramic sintered substrate according to claim 16, wherein the metal powder comprises at least one selected from Cu, Cr, and Ni.

18. The ceramic sintered substrate according to claim 16, wherein the ceramic substrate comprises at least one selected from silicon nitride, aluminum nitride, and boron nitride.

19. The ceramic sintered substrate according to claim 16, wherein the metal compound comprises at least one element selected from Ti, Ce, Zr, and Mg.

20. The ceramic sintered substrate according to claim 16, wherein the median diameter of the metal powder is 1 μm or more and 50 μm or less.

21. When the ceramic substrate is cut horizontally, the through-hole is circular. The ceramic sintered substrate according to claim 16, wherein the diameter of the through hole is 0.05 mm or more and 0.5 mm or less.

22. A light-emitting device comprising a ceramic sintered substrate according to any one of claims 16 to 21, and a light-emitting element electrically connected to the first metal body of the ceramic sintered substrate.

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