Ceramic substrates and light-emitting devices, and methods for manufacturing the same.

Abstract

To provide low-cost, highly reliable ceramic substrates and light-emitting devices, as well as methods for manufacturing them. [Solution] The ceramic substrate of the present disclosure comprises a ceramic plate containing aluminum nitride and a first wiring portion disposed on the upper surface of the ceramic plate, wherein the first wiring portion comprises an Al layer disposed on the upper surface of the ceramic plate, a metal layer disposed on the upper surface of the Al layer containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer disposed on the upper surface and the side surface of the metal layer, wherein the surface of the ceramic plate where the Al layer is disposed is rougher than the surface of the ceramic plate where the Al layer is not disposed, and in cross-sectional view, the minimum thickness of the metal layer in the region between position Pa and position Pb of the metal layer is 18 μm or more.

Description

[Technical Field]

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

[0002] In recent years, miniaturization of microchips (semiconductor integrated circuits) has been required to achieve smaller size, higher functionality, and greater integration of electronic devices and components. Photolithography and sputtering techniques are commonly used to create finer wiring within semiconductors. However, these techniques are expensive, and the increased number of steps required to form the wiring can lead to higher manufacturing costs.

[0003] For example, as a method for manufacturing ceramic circuit boards that can be produced cheaply by keeping processing costs low, a method has been proposed in which a laser is irradiated onto the surface of a ceramic substrate mainly composed of AlN or Al2O3 to form an aluminum conductor on the surface of the ceramic substrate, and then a plating is formed on the aluminum conductor (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-211390 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This disclosure aims to provide low-cost, highly reliable ceramic substrates and light-emitting devices, as well as methods for manufacturing them. [Means for solving the problem]

[0006] A ceramic substrate according to one embodiment of the present disclosure comprises a ceramic plate containing aluminum nitride and a first wiring portion disposed on the upper surface of the ceramic plate, wherein the first wiring portion comprises an Al layer disposed on the upper surface of the ceramic plate, a metal layer disposed on the upper surface of the Al layer containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer disposed on the upper surface and the side surface of the metal layer, wherein the surface of the ceramic plate where the Al layer is disposed is rougher than the surface of the ceramic plate where the Al layer is not disposed, and in a cross-sectional view, when the horizontal length between one end of the metal layer and the other end of the metal layer is Lw, the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer is Pa, and the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer is Pb, the minimum thickness of the metal layer in the region between Pa and Pb is 18 μm or more.

[0007] A ceramic substrate according to one embodiment of the present disclosure comprises a ceramic plate containing aluminum nitride and a first wiring portion disposed on the upper surface of the ceramic plate, wherein the first wiring portion comprises an Al layer disposed on the upper surface of the ceramic plate, a metal layer disposed on the upper surface of the Al layer containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer disposed on the upper surface and the side surface of the metal layer, wherein the surface of the ceramic plate where the Al layer is disposed is rougher than the surface of the ceramic plate where the Al layer is not disposed, and in a cross-sectional view, when the horizontal length between one end of the metal layer and the other end of the metal layer is Lw, the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer is Pa, and the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer is Pb, the average thickness of the metal layer in the region between Pa and Pb is 20 μm or more.

[0008] Furthermore, a light-emitting device according to one embodiment of the present disclosure comprises a ceramic substrate according to one embodiment of the present disclosure and a light-emitting element disposed on the ceramic substrate.

[0009] Furthermore, a method for manufacturing a ceramic substrate according to one embodiment of the present disclosure is a method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, and includes forming the first wiring portion, wherein forming the first wiring portion involves placing a first resist layer on the upper surface of a ceramic plate containing aluminum nitride, irradiating the first resist layer with laser light so as to penetrate it and deposit Al on the upper surface of the ceramic plate to form an Al layer, and plating the inside of the through-holes of the first resist layer and the upper surface of the Al layer with one or more metals selected from the group consisting of Zn, Ni, and Cu. The process includes forming a metal layer with a minimum thickness of 18 μm or more, removing the first resist layer, and forming an Au layer on the upper surface and side surface of the metal layer, wherein the minimum thickness of the metal layer is the minimum thickness of the metal layer in the region between Pa and Pb, where Lw is the horizontal length between one end of the metal layer and the other end of the metal layer in a cross-sectional view, Pa is the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer.

[0010] Furthermore, a method for manufacturing a ceramic substrate according to one embodiment of the present disclosure is a method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, and includes forming the first wiring portion, wherein forming the first wiring portion involves placing a first resist layer on the upper surface of a ceramic plate containing aluminum nitride, irradiating the first resist layer with laser light so as to penetrate it and deposit Al on the upper surface of the ceramic plate to form an Al layer, and plating the inside of the through-holes of the first resist layer and the upper surface of the Al layer with one or more metals selected from the group consisting of Zn, Ni, and Cu. The process includes forming a metal layer with an average thickness of 20 μm or more, removing the first resist layer, and forming an Au layer on the upper surface and the side surface of the metal layer, wherein the average thickness of the metal layer is the average thickness of the metal layer in the region between Pa and Pb, where Lw is the horizontal length between one end of the metal layer and the other end of the metal layer in a cross-sectional view, Pa is the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer.

[0011] Furthermore, a method for manufacturing a light-emitting device according to one embodiment of the present disclosure includes preparing the ceramic substrate manufactured by the method for manufacturing a ceramic substrate according to one embodiment of the present disclosure, and arranging a light-emitting element equipped with electrodes on the ceramic substrate, and electrically connecting the electrodes and the first wiring section. [Effects of the Invention]

[0012] According to one embodiment of the present disclosure, it is possible to provide low-cost, highly reliable ceramic substrates and light-emitting devices, as well as methods for manufacturing them. [Brief explanation of the drawing]

[0013] [Figure 1A] This is a schematic cross-sectional view showing an example of a ceramic substrate according to the first embodiment. [Figure 1B]It is a schematic top view showing an example of a ceramic substrate according to the first embodiment. [Figure 1C] It is an enlarged cross-sectional view of the region IC in FIG. 1A. [Figure 1D] It is a schematic cross-sectional view showing another example of a ceramic substrate according to the first embodiment. [Figure 1E] It is a schematic top view showing another example of a ceramic substrate according to the first embodiment. [Figure 2] It is a schematic cross-sectional view showing an example of a ceramic substrate according to the second embodiment. [Figure 3] It is a schematic cross-sectional view showing an example of a ceramic substrate according to the third embodiment. [Figure 4A] It is a schematic cross-sectional view showing an example of a ceramic substrate according to the fourth embodiment. [Figure 4B] It is a schematic top view showing an example of a ceramic substrate according to the fourth embodiment. [Figure 5A] It is a schematic cross-sectional view showing an example of a ceramic substrate according to the fifth embodiment. [Figure 5B] It is a schematic top view showing an example of a ceramic substrate according to the fifth embodiment. [Figure 6] It is a schematic cross-sectional view showing an example of a ceramic substrate according to the sixth embodiment. [Figure 7A] It is a schematic top view showing an example of a ceramic substrate according to the seventh embodiment. [Figure 7B] It is a schematic cross-sectional view in the stacking direction along the line VIIB-VIIB of FIG. 7A. [Figure 7C] It is an enlarged cross-sectional view of the region VIIC in FIG. 7B of the ceramic substrate according to the 7-1 embodiment. [Figure 7D] It is an enlarged cross-sectional view of the region VIIC in FIG. 7B of the ceramic substrate according to the 7-2 embodiment. [Figure 7E] It is a schematic bottom view showing an example of a ceramic substrate according to the seventh embodiment. [Figure 8] It is a flowchart showing an example of a manufacturing method of a ceramic substrate according to the first embodiment. [Figure 9A] This is a schematic cross-sectional view showing an example of a ceramic plate used in the manufacturing method of a ceramic substrate according to the first embodiment. [Figure 9B] This is a schematic cross-sectional view showing an example of arranging the first resist layer in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 9C] This is a schematic cross-sectional view showing an example of forming an Al layer in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 9D] This is a schematic cross-sectional view showing an example of forming a metal layer in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 9E] This is a schematic cross-sectional view showing an example of removing the first resist layer in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 9F] Figure 9E is an enlarged cross-sectional view of region IXF. [Figure 9G] This is a schematic cross-sectional view showing an example of forming an Au layer in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 9H] This is a schematic cross-sectional view showing an example of forming a heat dissipation section in the manufacturing method of a ceramic substrate according to the first embodiment. [Figure 10A] This is a schematic cross-sectional view showing an example of forming an Al layer in the method for manufacturing a ceramic substrate according to the third embodiment. [Figure 10B] This is a schematic cross-sectional view showing an example of forming a metal layer and an Au layer in a method for manufacturing a ceramic substrate according to the third embodiment. [Figure 11A] This is a schematic cross-sectional view showing an example of forming an Al layer in the method for manufacturing a ceramic substrate according to the fourth embodiment. [Figure 11B] This is an enlarged view of region XIB in Figure 11A. [Figure 11C] This is a schematic cross-sectional view showing an example of forming a metal layer in a method for manufacturing a ceramic substrate according to the fourth embodiment. [Figure 11D]This is a schematic cross-sectional view showing an example of forming an Au layer in a method for manufacturing a ceramic substrate according to the fourth embodiment. [Figure 11E] This is a schematic top view of a ceramic substrate according to the fourth embodiment. [Figure 12] This is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the fifth embodiment. [Figure 13A] This is a schematic cross-sectional view showing an example of forming an intermediate layer in the method for manufacturing a ceramic substrate according to the fifth embodiment. [Figure 13B] This is a schematic cross-sectional view showing an example of forming an Au layer in the method for manufacturing a ceramic substrate according to the fifth embodiment. [Figure 14] This is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the sixth embodiment. [Figure 15A] This is a schematic cross-sectional view showing an example of forming a first intermediate layer in the method for manufacturing a ceramic substrate according to the sixth embodiment. [Figure 15B] This is a schematic cross-sectional view showing an example of forming a second intermediate layer in the method for manufacturing a ceramic substrate according to the sixth embodiment. [Figure 15C] This is a schematic cross-sectional view showing an example of forming an Au layer in the method for manufacturing a ceramic substrate according to the sixth embodiment. [Figure 16] This is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the seventh embodiment. [Figure 17] This is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the eighth embodiment. [Figure 18] This is a schematic cross-sectional view of a ceramic substrate 100 manufactured by forming a wiring portion in the method for manufacturing a ceramic substrate according to the eighth embodiment. [Figure 19A] This is a schematic top view showing an example of a light-emitting device according to the embodiment. [Figure 19B] Figure 19A is a schematic cross-sectional view along the XIXB-XIXB line in the stacking direction. [Figure 19C]Figure 19B is an enlarged cross-sectional view of region XIXC. [Figure 20] This is a flowchart showing an example of a method for manufacturing a light-emitting device according to an embodiment. [Figure 21A] This is a photograph of Example 1. [Figure 21B] This is a photograph from Reference Example 1. [Modes for carrying out the invention]

[0014] A ceramic substrate and a light-emitting device according to the embodiments of this disclosure, as well as a method for manufacturing them, will be described in detail with reference to the drawings. However, the embodiments described below are illustrative examples of ceramic substrates and light-emitting devices and methods for manufacturing them that embody the technical concept of this disclosure, and are not limited to those described below.

[0015] Furthermore, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments are merely illustrative examples and not intended to limit the scope of this disclosure unless otherwise specified. Note that the size and positional relationships of the components shown in each drawing may be exaggerated for clarity. Also, in the following description, the same name and reference numeral indicate the same or identical components, and detailed explanations are omitted as appropriate. To avoid overly complex drawings, schematic diagrams may be used with some elements omitted, or end views showing only the cross-section may be used as cross-sectional views.

[0016] Furthermore, in this disclosure, the term "polygon" refers to polygons such as rectangles, triangles, and quadrilaterals, including shapes where the corners of the polygon have been rounded, chamfered, or otherwise modified. Similarly, shapes where modifications have been made not only to the corners (ends of the sides) but also to the middle parts of the sides will also be referred to as polygons. In other words, shapes that retain the shape of a polygon but have been partially modified are included in the interpretation of "polygon" as described in this disclosure.

[0017] Furthermore, the same applies not only to polygons but also to terms describing specific shapes such as trapezoids, circles, and convex shapes. The same also applies when dealing with each side that forms such a shape. In other words, even if a side has been processed at a corner or in the middle, the interpretation of "side" includes the processed part. When distinguishing a "polygon" or "side" without partial processing from a processed shape, the term "strictly" should be added, for example, "strictly quadrilateral."

[0018] Furthermore, the following description uses terms to indicate specific directions or positions as needed (e.g., "up," "down," "side," "top surface," "bottom surface," "side," "X," "Y," "Z," and other terms including these terms). However, the use of these terms is solely to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not excessively limit the technical scope of the present invention. For example, if "top surface" is mentioned, the invention does not necessarily have to be used in a way that it always faces upwards. Also, in the embodiments, "covering" is not limited to direct contact, but also includes indirect covering, for example, through other components.

[0019] Furthermore, in this specification or the claims, when there are multiple components and each is to be expressed separately, the components may be distinguished by adding "first," "second," etc., to their names.

[0020] [Ceramic substrate] <First Embodiment> Figure 1A is a schematic cross-sectional view showing an example of a ceramic substrate according to the first embodiment. Figure 1B is a schematic top view showing an example of a ceramic substrate according to the first embodiment. Figure 1C is an enlarged cross-sectional view of the region IC in Figure 1A. The various components of the ceramic substrate 100 according to the first embodiment will be described below.

[0021] The ceramic substrate 100 according to the first embodiment includes a ceramic plate 1 containing aluminum nitride and a first wiring section 2A disposed on the upper surface 1U of the ceramic plate 1. The first wiring section 2A includes an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 and containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer 5 disposed on the upper surface and side surface of the metal layer 4. In the ceramic plate 1, the surface 1A of the ceramic plate 1 where the Al layer 3 is disposed is rougher than the surface 1B of the ceramic plate 1 where the Al layer 3 is not disposed. In a cross-sectional view, if Lw is the horizontal length between one end 4A and the other end 4B of the metal layer 4, Pa is the position Lw / 5 from the one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4, then the minimum thickness of the metal layer 4 in the region between Pa and Pb is 18 μm or more. The ceramic substrate 100 according to the first embodiment may further have other configurations as needed.

[0022] The stacking direction in which the ceramic plate 1, Al layer 3, metal layer 4, and Au layer 5 are stacked is the Z-axis direction. The axis perpendicular to the Z-axis direction, which is the stacking direction, is the X-axis. The axis perpendicular to both the Z-axis direction and the X-axis direction is the Y-axis. The X-axis, Y-axis, and Z-axis are orthogonal to each other. The horizontal direction of the ceramic plate 1 may be perpendicular to the Z-axis direction, which is the stacking direction, and may be the X-axis direction or the Y-axis direction. In this specification, the XY plane is defined as the horizontal plane of the ceramic substrate 100, and both the X-axis direction and the Y-axis direction are defined as the horizontal direction of the ceramic substrate 100.

[0023] (Ceramic plate 1) The ceramic plate 1 is an insulating member that serves as a base for arranging the first wiring section 2A, which has an Al layer 3, a metal layer 4, and an Au layer 5. It is preferable that the ceramic plate 1 is sintered and not in a softened state before sintering.

[0024] The ceramic plate 1 contains aluminum nitride. Preferably, the ceramic plate 1 contains aluminum nitride as the main material, and may also contain other auxiliary materials as needed. Here, "main material" means the material that makes up the largest amount of material in the materials constituting the ceramic plate 1.

[0025] There are no particular restrictions on the auxiliary materials used in the ceramic plate 1, but examples include ceramics other than aluminum nitride, glass, etc. These may be used individually or in combination of two or more types.

[0026] Other ceramics besides aluminum nitride are not particularly limited and include, for example, nitride-based ceramics such as silicon nitride and boron nitride; oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide; silicon carbide; mullite; and borosilicate glass. These may be used individually or in combination of two or more.

[0027] There are no particular restrictions on the horizontal planar shape of the ceramic plate 1, and it can be various shapes such as circles, ellipses, polygons such as squares and hexagons, polygons with rounded corners, or shapes that combine these shapes. Among these, the ceramic plate 1 is preferably a plate-shaped member whose horizontal planar shape (outer shape) is rectangular. This rectangle may be a rectangle with a long side and a short side. Unless otherwise specified, a square may also be included in the definition of a rectangle. The planar shape and dimensions of the ceramic plate 1 can be appropriately adjusted according to the required performance, such as the dimensions and number of Al layers 3 etc. placed on it.

[0028] The upper surface 1U of the ceramic plate 1 is rougher on the surface 1A where the Al layer 3 is placed than on the surface 1B where the Al layer 3 is not placed. That is, the surface 1A on the upper surface 1U of the ceramic plate 1 has irregularities and is roughened. The recesses on the surface 1A of the ceramic plate 1 have an irregular microstructure. In this disclosure, the irregular microstructure of the recesses on the surface 1A of the ceramic plate 1 may be referred to as, for example, dendritic or tree-like.

[0029] There are no particular restrictions on the surface roughness Ra of the surface 1A of the ceramic plate 1 where the Al layer 3 is placed, but it is preferably 0.5 μm or more and 2.0 μm or less. If the surface roughness Ra of the surface 1A of the ceramic plate 1 where the Al layer 3 is placed is 0.5 μm or more, the adhesion with the Al layer 3 can be improved, and if it is 2.0 μm or less, it is preferable because the Ra of the plated wiring formed afterward will not become too rough and impair the mountability.

[0030] Furthermore, there are no particular restrictions on the surface roughness Ra of the surface 1B of the ceramic plate 1 in areas where the Al layer 3 is not present, but it is preferable that it be less than 0.5 μm.

[0031] In this disclosure, the surface roughness Ra of surfaces 1A and 1B of the ceramic plate 1 is a value measured in accordance with JIS B 0601:2013 using a stylus-type surface roughness meter (for example, SE3500 manufactured by Kosaka Laboratory Co., Ltd.) equipped with a diamond stylus with a tip radius of curvature r of 2 μm.

[0032] The lower surface 1L of the ceramic plate 1 is the surface of the ceramic plate 1 opposite to the upper surface 1U on which the first wiring section 2A is arranged. The lower surface 1L of the ceramic plate 1 does not have to be flat, but it is preferable that it be flat. This is because if the lower surface 1L of the ceramic plate 1 is flat, the ceramic substrate 100 can be suitably arranged on the mounting substrate when used in a light-emitting device.

[0033] The upper surface 1U and lower surface 1L of the ceramic plate 1 are preferably parallel. Here, when describing the surfaces of the ceramic plate 1 as "parallel," a difference of ±5 degrees is permitted.

[0034] There are no particular restrictions on the average thickness of the ceramic plate 1, but it is preferably 100 μm or more and 1,000 μm or less, and more preferably 120 μm or more and 500 μm or less.

[0035] The average thickness of ceramic plate 1 is calculated by measuring the thickness at two arbitrarily selected corners of ceramic plate 1 and averaging the two measurements. The thickness of the corners of ceramic plate 1 is measured using a macro gauge.

[0036] (1st wiring section 2A) In the ceramic substrate 100, the first wiring section 2A has a laminated structure in which an Al layer 3, a metal layer 4, and an Au layer 5 are laminated on the upper surface 1U of the ceramic plate 1. That is, in the area of ​​the upper surface 1U of the ceramic substrate 100 other than the first wiring section 2A, the upper surface 1U of the ceramic plate 1 is exposed. When the ceramic substrate 100 is used in a light-emitting device, the light-emitting element is suitably arranged on the first wiring section 2A.

[0037] There are no particular restrictions on the planar shape of the first wiring section 2A on the ceramic substrate 100, but when the ceramic substrate 100 is used in a light-emitting device, it is preferable to have a shape that corresponds to the electrode shape and layout of the light-emitting element 20.

[0038] -Metal layer 4- The metal layer 4 is placed on the upper surface of the Al layer 3. The upper surface of the Al layer 3 is covered by the metal layer 4, and the sides and top surface of the metal layer 4 are covered by the Au layer 5. As a result, the metal layer 4 is not affected by external environmental factors such as air, corrosion can be suppressed, and a highly reliable ceramic substrate 100 can be obtained.

[0039] The metal layer 4 contains one or more metals selected from the group consisting of Zn, Ni, and Cu. The metal layer 4 is made of a material with a lower ionization tendency than Al, which constitutes the Al layer 3.

[0040] The surface of the metal layer 4 that contacts the Al layer 3 is preferably roughened and has irregularities, similar to the surface 1A on the upper surface 1U of the ceramic plate 1. There are no particular restrictions on the surface roughness Ra of the surface of the metal layer 4 that contacts the Al layer 3, but it is preferably 0.2 μm or more and 2.0 μm or less, and more preferably 0.5 μm or more and 1.0 μm or less. If the surface roughness Ra of the surface of the metal layer 4 that contacts the Al layer 3 is 0.2 μm or more, the adhesion with the Al layer 3 can be improved.

[0041] In this disclosure, the surface roughness Ra of the surface of the metal layer 4 in contact with the Al layer 3 is a value measured in the same manner as the surface roughness Ra of surfaces 1A and 1B of the ceramic plate 1.

[0042] If the surface of the metal layer 4 that contacts the Al layer 3 is roughened and has irregularities, then Al is present in the recesses of this surface of the metal layer 4 that contacts the Al layer 3. In other words, the metal constituting the metal layer 4 is present in the recesses of the surface of the Al layer 3 that contacts the metal layer 4. Thus, the lower surface of the metal layer 4 on the side where the Al layer 3 is located contains the metal constituting the metal layer 4 and Al.

[0043] In a cross-sectional view, let Lw be the horizontal length between one end 4A and the other end 4B of the metal layer 4, let Pa be the position Lw / 5 from the one end 4A toward the horizontal center of the metal layer 4, and let Pb be the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4. Then, the minimum thickness of the metal layer in the region between Pa and Pb is 18 μm or more, and preferably 20 μm or more.

[0044] In the ceramic substrate 100 according to the first embodiment, the minimum thickness of the metal layer 4 is measured as follows. A scanning electron microscope (SEM) image is obtained at a magnification of 250x in a cross-section of the ceramic substrate 100 that is in the thickness direction (Z-axis direction) and passes through the region between Pa and Pb, and includes a region that includes at least 25 μm in the depth direction of the recess from the surface of the metal layer 4 that is in contact with the Al layer 3, and a region that includes at least a part of the Au layer 5. In the SEM image of region X, the length la connecting the root-shaped recess bottom A extending from the lower surface of the metal layer 4 (the surface in contact with the Al layer 3) toward the Al layer 3 side and the surface in contact with the Au layer 5 located opposite the recess bottom A is measured. Similarly, the lengths la of five arbitrarily selected locations within region X are measured, and the smallest length La among the five lengths la is measured. min This is defined as the minimum thickness of the metal layer 4 in the ceramic substrate 100 according to the first embodiment.

[0045] In a cross-sectional view of the ceramic substrate 100 in the thickness direction (Z-axis direction), there are no particular restrictions on the outer angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4, but it is preferably 85° or more and 95° or less, and more preferably 88° or more and 92° or less.

[0046] The external angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4 is measured as follows: Obtain a scanning electron microscope (SEM) image at a magnification of 250x, in the thickness direction (Z-axis direction) of the ceramic substrate 100, including the upper surface 1U of the ceramic plate 1 and the metal layer 4. Since the upper surface 1U of the ceramic plate 1 and the lower surface of the metal layer 4 are not in direct contact, a virtual line V is drawn in the SEM image, extending from the side surface of the metal layer 4 towards the upper surface 1U of the ceramic plate 1. The angle between the side surface of this virtual line V on the Au layer 5 side and the upper surface 1U of the ceramic plate 1 is defined as the external angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4.

[0047] In the ceramic substrate 100 according to the first embodiment, the entire lower surface of the metal layer 4 is in contact with the upper surface of the Al layer 3. As a result, in a plan view in the horizontal direction (X-axis or Y-axis direction), the edge 3a of the upper surface of the Al layer 3 and the edge 4b ​​of the lower surface of the metal layer 4 coincide. That is, in a plan view in the horizontal direction (X-axis or Y-axis direction), the area of ​​the metal layer 4 is 100% of the area of ​​the Al layer 3, but this is not limited to this case.

[0048] Figure 1D is a schematic cross-sectional view showing another example of a ceramic substrate according to the first embodiment. Figure 1E is a schematic top view showing another example of a ceramic substrate according to the first embodiment. Thus, in a plan view in the horizontal direction (X-axis or Y-axis direction), the edge 3a of the upper surface of the Al layer 3 may be outside the edge 4b ​​of the lower surface of the metal layer 4. Even in this case, it is preferable that the edge 3a of the upper surface of the Al layer 3 is inside the edge 5b of the lower surface of the Au layer 5.

[0049] In a plan view in the horizontal direction (X-axis or Y-axis direction), the area of ​​the metal layer 4 is preferably 100% to 110% of the area of ​​the Al layer 3, and more preferably 100% to 105%. Here, the area of ​​the Al layer 3 refers to the area of ​​the upper surface of the Al layer 3, and the area of ​​the metal layer 4 refers to the area of ​​the lower surface of the metal layer 4. It is preferable that the areas of the lower and upper surfaces of the metal layer 4, in relation to the area of ​​the upper surface of the Al layer 3, satisfy the above preferred range.

[0050] -Al layer 3- The Al layer 3 is placed on the upper surface 1U of the ceramic plate 1. Specifically, the Al layer 3 is placed on part or all of the interface between the surface 1A and the metal layer 4 on the upper surface 1U of the ceramic plate 1, and preferably it is placed continuously across the entire interface between the surface 1A and the metal layer 4 of the ceramic plate 1. The Al layer 3 improves the adhesion between the surface 1A and the metal layer 4 of the ceramic plate 1.

[0051] As described above, the upper surface 1U of the ceramic plate 1 has a rougher surface 1A where the Al layer 3 is placed than the surface 1B where the Al layer 3 is not placed, and has an irregular microstructure. Al is present in the dendritic depressions of surface 1A of the ceramic plate 1. Therefore, the surface of the Al layer 3 that is in contact with surface 1A of the ceramic plate 1 also has irregularities and is roughened to follow the surface 1A of the ceramic plate 1. In other words, the material constituting the ceramic plate 1 is present in the dendritic depressions of the lower surface of the Al layer. Thus, the lower surface of the Al layer 3 on the side where the ceramic plate 1 is placed contains the material constituting the ceramic plate 1 and Al.

[0052] Here, having the Al layer 3 "continuously" means that Al is present in the dendritic recesses on the surface 1A of the ceramic plate 1, and that Al is arranged on the surface 1A of the ceramic plate 1 without interruption. The Al layer 3 is arranged over almost the entire surface 1A of the upper surface 1U of the ceramic plate 1. Depending on the processing state, the Al layer 3 may not be arranged in part on the surface 1A of the upper surface 1U of the ceramic plate 1, but the Al layer 3 is arranged over 80% or more, preferably 90% or more, and more preferably 95% or more of the surface 1A of the upper surface 1U of the ceramic plate 1.

[0053] It is preferable that the surface of the Al layer 3 that contacts the metal layer 4 has irregularities and is roughened, similar to the surface 1A of the ceramic plate 1 of the Al layer 3. There are no particular restrictions on the surface roughness Ra of the surface of the Al layer 3 that contacts the metal layer 4, but since the lower surface of the metal layer 4 has irregularities that follow the upper surface of the Al layer 3, it is the same as the surface roughness Ra of the surface of the metal layer 4 that contacts the Al layer 3.

[0054] In this disclosure, the surface roughness Ra of the surface of the Al layer 3 that is in contact with the surface 1A of the ceramic plate 1 is a value measured in the same way as the surface roughness Ra of surfaces 1A and 1B of the ceramic plate 1.

[0055] In a cross-sectional view, let Lz be the horizontal length (in the X or Y direction) between one end 3A of the Al layer 3 and the other end 3B of the Al layer 3. Let Pc be the position Lz / 5 from the end 3A of the Al layer 3 toward the center of the Al layer 3 in the horizontal direction (in the X or Y direction), and let Pd be the position Lz / 5 from the other end 3B of the Al layer 3 toward the center of the Al layer 3 in the horizontal direction (in the X or Y direction). There are no particular restrictions on the average thickness of the Al layer 3 in the region between Pc and Pd, but it is preferably 0.2 μm or more and 5 μm or less, and more preferably 0.5 μm or more and 2 μm or less.

[0056] In the ceramic substrate 100 according to the first embodiment, the average thickness of the Al layer 3 is measured as follows: A scanning electron microscope (SEM) image is obtained at a magnification of 250x in a cross-section of the ceramic substrate 100 that is in the thickness direction (Z-axis direction) and passes through the region between Pc and Pd, and includes a region that includes at least 25 μm in the depth direction of the recess from the surface 1A on the upper surface 1U of the ceramic plate 1, and a region that includes at least 25 μm in the depth direction of the recess from the surface of the Al layer 3 that is in contact with the metal layer 4. In the SEM image of region Y, the length lb connecting the root-shaped recess bottom B extending from the surface 1A on the upper surface 1U of the ceramic plate 1 towards the ceramic plate 1 and the root-shaped recess bottom A located opposite the recess bottom B and extending from the lower surface of the metal layer 4 (the surface in contact with the Al layer 3) towards the Al layer 3 is measured. Similarly, the lengths lb of five arbitrarily selected locations within region Y are measured, and the average length Lb of the five locations is measured. ave This is defined as the average thickness of the Al layer 3 in the ceramic substrate 100 according to the first embodiment.

[0057] There are no particular restrictions on the size of the Al layer 3 in the horizontal direction (X-axis or Y-axis direction), but it is preferable that the upper edge 3a of the Al layer 3 is located inside the lower edge 5b of the Au layer 5 in the horizontal direction (X-axis or Y-axis direction). Specifically, in the horizontal direction, it is preferable that the upper edge 3a of the Al layer 3 is located 1.0 μm to 5.0 μm inside the lower edge 5b of the Au layer 5, and more preferably 1.2 μm to 3 μm inside. The inner region surrounded by the lower edge 5b of the Au layer 5 is defined as the inside of the lower edge 5b of the Au layer 5, and the outer region surrounded by the lower edge 5b of the Au layer 5 is defined as the outside of the lower edge 5b of the Au layer 5. When the upper edge 3a of the Al layer 3 is located inside the lower edge 5b of the Au layer 5 in the horizontal direction, corrosion of the Al layer 3 can be suitably suppressed, resulting in a highly reliable ceramic substrate 100.

[0058] Furthermore, it is preferable that the sides of the Al layer 3 are covered by the Au layer 5, and that the upper surface 1U of the ceramic plate 1 and the lower surface of the Au layer 5 are in contact. As a result, the Al layer 3 is not exposed, which can more effectively suppress corrosion of the Al layer 3 and result in a more reliable ceramic substrate 100.

[0059] -Au layer 5- The Au layer 5 is placed on the upper surface and the side surface of the metal layer 4. The Au layer 5 is the outermost layer in the first wiring section 2A.

[0060] By making the outermost surface of the first wiring section 2A an Au layer 5, the reliability of the connection with the light-emitting element 20 is improved when the ceramic substrate 100 is used in the light-emitting device. Since the electrodes of the light-emitting element 20 are usually made of gold, the connection between the Au layer 5 in the first wiring section 2A and the Au electrodes of the light-emitting element 20 is highly reliable, and a reliable connection can be maintained over a long period of time without degradation even when high voltage is applied.

[0061] The horizontal planar shape and dimensions of the Au layer 5 can be appropriately adjusted to match the planar shape and dimensions of the metal layer 4.

[0062] There are no particular restrictions on the average thickness of the Au layer 5, but it is preferably 0.03 μm or more and 1 μm or less, and more preferably 0.05 μm or more and 0.1 μm or less.

[0063] The average thickness of the Au layer 5 is calculated by scanning an electron microscope (SEM) to capture a cross-section of the region containing the Au layer 5 of the ceramic substrate 100 in the thickness direction (Z-axis direction), measuring the thickness of the Au layer 5 at three arbitrarily selected locations within the field of view of the SEM image (for example, one location from the center and two locations from the edges), and calculating the average of the three measurements.

[0064] (Other configurations) Other components of the ceramic substrate 100 include, for example, a heat dissipation section 10.

[0065] -Heat dissipation part 10- The ceramic substrate 100 may have a heat dissipation section 10 on the lower surface 1L of the ceramic plate 1. Preferably, the heat dissipation section 10 is provided so as to overlap with the area directly below the first wiring section 2A where the light-emitting element 20 is arranged, in a horizontal plan view. The horizontal (X-axis or Y-axis) plan view shape of the heat dissipation section 10 is preferably larger in area. The shape, structure, and dimensions of the heat dissipation section 10 are not particularly limited and can be appropriately selected according to the purpose. The heat dissipation section 10 can be made of the same metal material as the first wiring section 2A.

[0066] Conventional light-emitting devices often use solder on the substrate, and repeated use in environments with large temperature differences can cause cracks (hereinafter sometimes referred to as "solder cracks") to occur in the solder joints due to thermal stress. Solder cracks are particularly likely to occur when there is a large difference in the coefficient of thermal expansion between the substrate and the metal component, and if the solder cracks progress, connection failures may occur. In contrast, the ceramic substrate 100 according to the first embodiment is joined to the ceramic plate 1 and the metal layer 4 by the Al layer 3 without the use of solder. Therefore, the ceramic substrate 100 according to the first embodiment has high resistance to solder cracks and high connection reliability.

[0067] <Second Embodiment> Figure 2 is a schematic cross-sectional view showing an example of a ceramic substrate according to the second embodiment. The ceramic substrate 100 according to the second embodiment includes a ceramic plate 1 containing aluminum nitride and a first wiring portion 2A disposed on the upper surface 1U of the ceramic plate 1. The first wiring portion 2A includes an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 and containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer 5 disposed on the upper surface and the side surface of the metal layer 4. In the ceramic plate 1, the surface 1A of the ceramic plate 1 where the Al layer 3 is disposed is rougher than the surface 1B of the ceramic plate 1 where the Al layer 3 is not disposed. In a cross-sectional view, if Lw is the horizontal length between one end 4A and the other end 4B of the metal layer 4, Pa is the position Lw / 5 from the end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4, then the average thickness of the metal layer 4 in the region between Pa and Pb is 20 μm or more.

[0068] The ceramic substrate 100 according to the second embodiment has the same configuration as the ceramic substrate 100 according to the first embodiment, except that the average thickness of the metal layer 4 in the region between Pa and Pb is 20 μm or more. Preferably, the average thickness of the metal layer 4 in the region between Pa and Pb is 25 μm or more. Furthermore, there is no particular upper limit to the average thickness of the metal layer 4 in the region between Pa and Pb, but it is preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 45 μm or less. The lower limit and upper limit of the average thickness of the metal layer 4 in the region between Pa and Pb can be combined as appropriate, for example, 20 μm or more and 60 μm or less, 20 μm or more and 50 μm or less, 20 μm or more and 45 μm or less, 25 μm or more and 50 μm or less, etc.

[0069] In the ceramic substrate 100 according to the second embodiment, the minimum thickness of the metal layer 4 in the region between Pa and Pb is not particularly limited, as long as the average thickness of the metal layer 4 is 20 μm or more, and can be appropriately selected according to the purpose. It may be 18 μm or more, or 20 μm or more. The minimum thickness of the metal layer 4 in the ceramic substrate 100 according to the second embodiment is a value measured by the same method as in the first embodiment.

[0070] In the ceramic substrate 100 according to the second embodiment, the average thickness of the metal layer 4 is measured as follows. A scanning electron microscope (SEM) image is obtained at a magnification of 250x in a cross-section of the ceramic substrate 100 that is in the thickness direction (Z-axis direction) and passes through the region between Pa and Pb, and includes a region that includes at least 25 μm in the depth direction of the recess from the surface of the metal layer 4 that is in contact with the Al layer 3, and a region that includes at least a part of the Au layer 5. In the SEM image of region X, the length la connecting the root-shaped recess bottom A extending from the lower surface of the metal layer 4 (the surface in contact with the Al layer 3) toward the Al layer 3 side and the surface in contact with the Au layer 5 located opposite the recess bottom A is measured. Similarly, the lengths la of five arbitrarily selected locations within region X are measured, and the average length La of the five locations is measured. aveThis is defined as the average thickness of the metal layer 4 in the ceramic substrate 100 according to the second embodiment.

[0071] <Third Embodiment> Figure 3 is a schematic cross-sectional view showing an example of a ceramic substrate according to the third embodiment. The ceramic substrate 100 according to the third embodiment has the same configuration as the ceramic substrate 100 according to the first embodiment or the ceramic substrate 100 according to the second embodiment, except that it has a plurality of first wiring sections 2A. Here, an example is shown in which there are two first wiring sections 2A, one first wiring section 2A1 and another first wiring section 2A2 adjacent to the first wiring section 2A1. However, there is no particular limit to the number of first wiring sections 2A as long as there are two or more, and can be appropriately selected depending on the configuration of the light-emitting device on which the ceramic substrate 100 is placed. The ceramic substrate 100 according to the third embodiment may have other configurations.

[0072] In multiple first wiring sections 2A, there are no particular restrictions on the shortest distance Lm between the side surface of the Au layer 5 in one first wiring section 2A1 and the side surface of the Au layer 5 in another first wiring section 2A2 adjacent to the first first wiring section 2A1, but it is preferably 10 μm or more and 100 μm or less, and more preferably 50 μm or more and 80 μm or less.

[0073] (Other configurations) The ceramic substrate 100 according to the third embodiment may have wiring sections different from the first wiring section 2A, the second wiring section 2B described later, and the pad section 12 described later.

[0074] -Other wiring sections- When the ceramic substrate 100 is used in a light-emitting device, it may further have wiring sections between the multiple first wiring sections 2A for making electrical connections to light-emitting elements, depending on the number of light-emitting elements to be mounted. For example, one or more relay wiring sections may be arranged between a pair of first wiring sections 2A. The shape and arrangement of the wiring sections arranged between the pair of first wiring sections 2A may be such that multiple light-emitting elements are driven independently, or they may be arranged to be driven in series, parallel, or a combination thereof, depending on the shape of the pair of first wiring sections 2A and their power supply control.

[0075] <Fourth Embodiment> Figure 4A is a schematic cross-sectional view showing an example of a ceramic substrate according to the fourth embodiment. Figure 4B is a schematic top view showing an example of a ceramic substrate according to the fourth embodiment. The ceramic substrate 100 according to the fourth embodiment has the same configuration as the ceramic substrate 100 according to the first embodiment or the ceramic substrate 100 according to the second embodiment, except that the first wiring portion 2A further has one intermediate layer 6 disposed on the upper surface and side surface of the metal layer 4.

[0076] -Middle layer 6- In the ceramic substrate 100 according to the fourth embodiment, the intermediate layer 6 is a single layer. The intermediate layer 6 can improve the adhesion between the metal layer 4 and the Au layer 5.

[0077] The sides of the Al layer 3 are covered by the intermediate layer 6, and the Au layer 5 is arranged on the upper surface and sides of the intermediate layer 6. Preferably, the upper surface 1U of the ceramic plate 1 and the lower surface of the intermediate layer 6 are in contact, and the upper surface 1U of the ceramic plate 1 and the lower surface of the Au layer 5 are in contact. This allows the Al layer 3 and the metal layer 4 to be unaffected by external environmental factors such as air, suppressing corrosion and resulting in a highly reliable ceramic substrate 100.

[0078] The horizontal planar shape and dimensions of the intermediate layer 6 can be appropriately adjusted to match the planar shape and dimensions of the metal layer 4, but it is preferable that the lower edge 6b of the intermediate layer 6 be positioned outside the upper edge 3a of the Al layer 3 in a planar view in the horizontal direction (X-axis or Y-axis direction). In this case, the lower edge 6b of the intermediate layer 6 is positioned outside the upper edge 3a of the Al layer 3 and inside the lower edge 5b of the Au layer 5 in a planar view in the horizontal direction (X-axis or Y-axis direction). The inner region enclosed by the lower edge 6b of the intermediate layer 6 is referred to as the inside of the lower edge 6b of the intermediate layer 6, and the outer region enclosed by the lower edge 6b of the intermediate layer 6 is referred to as the outside of the lower edge 6b of the intermediate layer 6.

[0079] There are no particular restrictions on the material of the intermediate layer 6, but it is preferably a conductive material, such as Ti, Ni, Pd, Pt, Rh, W, Ru, etc. These may be used individually or in combination of two or more. Among these, it is preferable that the intermediate layer 6 contains Ni and Pd. When the intermediate layer 6 is made by electroless plating, Ni, NiP, NiB, Pd, etc. are preferred.

[0080] There are no particular restrictions on the average thickness of the intermediate layer 6, but it is preferably 0.03 μm or more and 1 μm or less, and more preferably 0.05 μm or more and 0.1 μm or less.

[0081] The average thickness of the intermediate layer 6 is determined by scanning an electron microscope (SEM) to capture a cross-section of the region containing the intermediate layer 6 of the ceramic substrate 100 in the thickness direction (Z-axis direction), measuring the thickness of the intermediate layer 6 at three arbitrarily selected locations within the field of view of the SEM image (for example, one location from the center and two locations from the edges), and calculating the average of the three measurements.

[0082] <Fifth Embodiment> Figure 5A is a schematic cross-sectional view showing an example of a ceramic substrate according to the fifth embodiment. Figure 5B is a schematic top view showing an example of a ceramic substrate according to the fifth embodiment. The ceramic substrate 100 according to the fifth embodiment has the same configuration as the ceramic substrate 100 according to the fourth embodiment, except that the intermediate layer 6 consists of two layers, a first intermediate layer 6-1 and a second intermediate layer 6-2.

[0083] The first intermediate layer 6-1 and the second intermediate layer 6-2 are made of different materials. Ni is preferred as the material for the first intermediate layer 6-1. Pd is preferred as the material for the second intermediate layer 6-2.

[0084] In the ceramic substrate 100 according to the fifth embodiment, the first intermediate layer 6-1 is arranged on the upper surface and side surface of the metal layer 4, and on the side surface of the Al layer 3, the second intermediate layer 6-2 is arranged on the upper surface and side surface of the first intermediate layer 6-1, and the Au layer 5 is arranged on the upper surface and side surface of the second intermediate layer 6-2.

[0085] Here, the entire lower surface of the first intermediate layer 6-1 and the entire lower surface of the second intermediate layer 6-2 are in contact with the upper surface 1U of the ceramic plate 1, but this is not limited to this. For example, only the entire lower surface of the first intermediate layer 6-1 may be in contact with the upper surface 1U of the ceramic plate 1, and the lower surface of the second intermediate layer 6-2 may not be in contact with the upper surface 1U of the ceramic plate 1; the entire lower surface of the first intermediate layer 6-1 and a part of the lower surface of the second intermediate layer 6-2 may be in contact with the upper surface 1U of the ceramic plate 1; and only a part of the lower surface of the first intermediate layer 6-1 may be in contact with the upper surface 1U of the ceramic plate 1, and the rest of the lower surface of the first intermediate layer 6-1 and the entire lower surface of the second intermediate layer 6-2 may not be in contact with the upper surface 1U of the ceramic plate 1.

[0086] The horizontal planar shapes and dimensions of the first intermediate layer 6-1 and the second intermediate layer 6-2 can be appropriately adjusted to match the planar shapes and dimensions of the metal layer 4. However, in a planar view in the horizontal direction (X-axis or Y-axis direction), it is preferable that the lower edge 6-1b of the first intermediate layer 6-1 is positioned outside the upper edge 3a of the Al layer 3. Similarly, it is preferable that the lower edge 6-2b of the second intermediate layer 6-2 is positioned outside the lower edge 6-1b of the first intermediate layer 6-1. In this case, in a planar view in the horizontal direction (X-axis or Y-axis direction), the lower edge 6-2b of the second intermediate layer 6-2 is positioned outside the upper edge 3a of the Al layer 3, outside the lower edge 6-1b of the first intermediate layer 6-1, and inside the lower edge 5b of the Au layer 5. Furthermore, the inner region enclosed by the lower edge 6-1b of the first intermediate layer 6-1 is defined as the inside of the lower edge 6-1b of the first intermediate layer 6-1, and the outer region enclosed by the lower edge 6-1b of the first intermediate layer 6-1 is defined as the outside of the lower edge 6-1b of the first intermediate layer 6-1. Similarly, the inner region enclosed by the lower edge 6-2b of the second intermediate layer 6-2 is defined as the inside of the lower edge 6-2b of the second intermediate layer 6-2, and the outer region enclosed by the lower edge 6-2b of the second intermediate layer 6-2 is defined as the outside of the lower edge 6-2b of the second intermediate layer 6-2.

[0087] In the fifth embodiment, the case where the ceramic substrate 100 has two intermediate layers 6 will be described, but in the ceramic substrate 100 according to the embodiment of this disclosure, the intermediate layers 6 may be three or more. When there are three or more intermediate layers 6, there are no particular restrictions on the material of each intermediate layer 6, and they can be appropriately selected according to the purpose.

[0088] <Sixth Embodiment> Figure 6 is a schematic cross-sectional view showing an example of a ceramic substrate according to the sixth embodiment. The ceramic substrate 100 according to the sixth embodiment has the same configuration as the ceramic substrate 100 according to the first embodiment or the ceramic substrate 100 according to the second embodiment, except that it further has a second wiring portion 2B arranged on the lower surface 1L of the ceramic plate 1, which is the surface opposite to the upper surface 1U of the ceramic plate 1, and preferably further has vias 11.

[0089] (2nd wiring section 2B) The second wiring section 2B, located on the ceramic substrate 100, has a laminated structure in which an Al layer 3, a metal layer 4, and an Au layer 5 are laminated on the lower surface 1L of the ceramic plate 1. That is, the lower surface 1L of the ceramic substrate 100 is exposed in areas other than the second wiring section 2B. The second wiring section 2B has the same configuration as the first wiring section 2A, except that it is located on the lower surface 1L of the ceramic substrate 100.

[0090] (Via 11) In the ceramic substrate 100 according to the sixth embodiment, the via 11 electrically connects the first wiring section 2A and the second wiring section 2B.

[0091] The via 11 is formed inside a through hole formed in the thickness direction (Z-axis direction) of the ceramic plate 1 and the Al layer 3.

[0092] The material constituting the via 11 is not particularly limited as long as it is conductive, and can be appropriately selected from known conductive materials, for example, the same material as the metal layer 4.

[0093] The shape, structure, and size of via 11 are not particularly limited, as long as they can electrically connect the first wiring section 2A and the second wiring section 2B, and can be appropriately selected according to the purpose.

[0094] <Seventh Embodiment> Figure 7A is a schematic top view showing an example of a ceramic substrate according to the seventh embodiment. The ceramic substrate 100 according to the seventh embodiment has the same configuration as the ceramic substrate 100 according to the first embodiment or the ceramic substrate 100 according to the second embodiment, except that it further has a pad portion 12 that is electrically connected to the Au layer 5.

[0095] (Pad section 12) The layer configuration of the pad portion 12 is not particularly limited as long as it can be electrically connected to the Au layer 5 in the first wiring portion 2A, and can be appropriately selected according to the purpose. Below, as examples of the pad portion 12, the pad portion 12A of the ceramic substrate 100 according to the 7-1 embodiment and the pad portion 12B of the ceramic substrate 100 according to the 7-2 embodiment will be described. On a single ceramic substrate 100, only one of the pad portion 12A and the pad portion 12B may be present, or both may be present simultaneously in separate regions.

[0096] There are no particular restrictions on the planar shape of the pad portion 12 in the horizontal direction (X-axis direction or Y-axis direction), but it is preferable that it extends from the first wiring portion 2A and is positioned near the edge of the ceramic substrate 100. By increasing the total planar area of ​​the first wiring portion 2A and the pad portion 12, when the ceramic substrate 100 is used as a light-emitting device, it is possible to create a light-emitting device in which current flows easily and electrical resistance is low. Here, "near the edge of the ceramic substrate 100" means that the distance from the outer edge of the ceramic plate 1 on the surface in which the first wiring portion 2A and the pad portion 12 are positioned to the first wiring portion 2A or the pad portion 12 is 0.01 mm or more and 0.5 mm or less.

[0097] Furthermore, by positioning the first wiring section 2A and the pad section 12 near the edge of the ceramic substrate 100, the connection length of the power supply member used to supply power to the external connection section, such as a wire, can be shortened, enabling reliable and easy power supply. Among these, the horizontal planar shape of the pad section 12 is preferably such that, in a ceramic substrate 100 with a planar shape that is substantially rectangular in the horizontal direction (X-axis or Y-axis), the positive and negative pair of external connection sections each extend toward one side of the rectangle. This allows the power supply member from the outside to be connected to either the positive or negative external connection section from the same direction and with approximately the same length.

[0098] <<Embodiment 7-1>> Figure 7B is a schematic cross-sectional view in the stacking direction along the VIIB-VIIB line in Figure 7A. Figure 7C is an enlarged cross-sectional view of the ceramic substrate according to the 7-1 embodiment in region VIIC of Figure 7B.

[0099] The pad portion 12A in the ceramic substrate 100 according to the 7-1 embodiment includes a ceramic plate 1, an Al layer 3 disposed on the upper surface of the ceramic plate 1, and an Au layer 5 disposed on the upper surface of the Al layer 3. Preferably, the pad portion 12A does not include a metal layer 4. This makes it possible to reduce the thickness of the pad portion 12A. When the ceramic substrate 100 is used in a light-emitting device, the heat dissipation of the light-emitting element can be improved by placing the metal layer 4 only in the first wiring portion 2A where the light-emitting element is arranged.

[0100] <<Embodiment 7-2>> Figure 7D is an enlarged cross-sectional view of the ceramic substrate according to the 7-2 embodiment in region VIIC of Figure 7B.

[0101] The pad portion 12B in the ceramic substrate 100 according to the 7-2 embodiment comprises a ceramic plate 1 and an Al layer 3 disposed on the upper surface of the ceramic plate 1. Preferably, the pad portion 12B does not include a metal layer 4. This makes it possible to reduce the thickness of the pad portion 12B. When the ceramic substrate 100 is used in a light-emitting device, the heat dissipation of the light-emitting element can be improved by placing the metal layer 4 only in the first wiring portion 2A where the light-emitting element is arranged. Also, when Al is used for the wire, it can be made of the same material as the surface of the pad portion 11B, which prevents breakage or disconnection of the wire and the pad portion 11B.

[0102] (Heat radiation part 10) Figure 7E is a schematic bottom view showing an example of a ceramic substrate according to the seventh embodiment. The heat dissipation section 10 can have a shape such as a combination of multiple rectangular patterns with comb-like cutouts.

[0103] [Method for manufacturing ceramic substrates] <First Embodiment> Figure 8 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the first embodiment. The method for manufacturing a ceramic substrate according to the first embodiment will be explained with reference to Figures 9A to 9H. Although this shows the method for manufacturing one ceramic substrate 100, multiple ceramic substrates 100 may be manufactured simultaneously.

[0104] A method for manufacturing a ceramic substrate according to the first embodiment is a method for manufacturing a ceramic substrate 100 having a first wiring portion 2A on the upper surface 1U of a ceramic plate 1, and includes forming the first wiring portion 2A, wherein forming the first wiring portion 2A includes arranging a first resist layer 50 on the upper surface 1U of a ceramic plate 1 containing aluminum nitride, irradiating a laser beam L that penetrates the first resist layer 50 and deposits Al on the upper surface 1U of the ceramic plate 1 to form an Al layer 3, plating the inside of the through-holes 51 of the first resist layer 50 and the upper surface of the Al layer 3 with one or more metals selected from the group consisting of Zn, Ni, and Cu to form a metal layer 4 with a minimum thickness of 18 μm or more, removing the first resist layer 50, and forming an Au layer 5 on the upper surface and side surface of the metal layer 4. The minimum thickness of the metal layer 4 is the minimum thickness of the metal layer 4 in the region between Pa and Pb, where Lw is the horizontal length between one end 4A and the other end 4B of the metal layer 4 in a cross-sectional view, Pa is the position Lw / 5 from the one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4. The method for manufacturing a ceramic substrate according to the first embodiment may further include forming a heat dissipation section 10.

[0105] (S10) Forming the first wiring section Forming the first wiring section S10 includes placing the first resist layer S10-1, forming an Al layer S10-2, forming a metal layer S10-3, removing the first resist layer S10-4, and forming an Au layer S10-5.

[0106] (S10-1) Place the first resist layer. Figure 9A is a schematic cross-sectional view showing an example of a ceramic plate used in the manufacturing method of a ceramic substrate according to the first embodiment. Figure 9B is a schematic cross-sectional view showing an example of arranging the first resist layer in the manufacturing method of a ceramic substrate according to the first embodiment.

[0107] Placing the first resist layer S10-1 involves providing the first resist layer 50 on the upper surface 1U of the ceramic plate 1 containing aluminum nitride.

[0108] Specifically, in S10-1, which involves placing the first resist layer, a ceramic plate 1 is first prepared. The ceramic plate 1 may be a ceramic precursor before sintering, or it may be a sintered ceramic, but it is preferable that it be a sintered ceramic because there is no dimensional change due to sintering.

[0109] Next, a first resist layer 50 is provided on the upper surface 1U of the ceramic plate 1. At this time, the first resist layer 50 may be provided over the entire upper surface 1U of the ceramic plate 1, or on a part of the upper surface 1U of the ceramic plate 1. The position on the upper surface 1U of the ceramic plate 1 where the first resist layer 50 is provided can be appropriately selected according to the desired position on the upper surface 1U of the ceramic plate 1 where the first wiring portion 2A is provided.

[0110] The first resist layer 50 is not particularly limited and can be formed using photoresist compositions or sheet-type resists (dry films) commonly used in the field of light-emitting devices. Specifically, the first resist layer 50 can be a photoresist composition made of various materials classified as novolac-diazonaphthoquinone (DNQ)-based photoresist, positive-type photoresist, negative-type photoresist, chemically amplified photoresist, photocrosslinked photoresist, photopolymerized photoresist, etc., or a dry film formed from these photoresist compositions. Any commercially available photoresist composition or dry film can be used. Among these, the first resist layer 50 is preferably formed using a negative-type photoresist, and more preferably using a dry film formed from a negative-type photoresist composition. By using a dry film, oxidation of the upper surface 1U of the ceramic plate 1 can be prevented, and in removing the first resist layer S10-4, the outer angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4 in a cross-sectional view in the thickness direction (Z-axis direction) of the ceramic plate 1 can be preferably set to 85° or more and 95° or less.

[0111] Methods for forming the first resist layer 50 using a photoresist composition include, for example, screen coating, spin coating, roll coating, laminator coating, dip coating, and spray coating.

[0112] Forming an (S10-2)Al layer Figure 9C is a schematic cross-sectional view showing an example of forming an Al layer in the manufacturing method of a ceramic substrate according to the first embodiment.

[0113] Forming the Al layer S10-2 involves irradiating the first resist layer 50 with laser light L so that Al is deposited on the upper surface 1U of the ceramic plate 1, thereby forming the Al layer 3. As a result, through holes 51 are formed in the first resist layer 50 at the irradiated areas of the laser light L, and the Al layer 3 is formed on the upper surface 1U of the ceramic plate 1 that is exposed by the formation of the through holes 51. At this time, the surface 1A of the ceramic plate 1 where the Al layer 3 was formed is rougher than the surface 1B of the ceramic plate 1 where it is covered by the first resist layer 50.

[0114] In forming the Al layer S10-2, it is preferable to irradiate the surface 1A of the upper surface 1U of the ceramic plate 1 with laser light L so that the surface roughness Ra is 0.5 μm or more and 2.0 μm or less, and more preferable to irradiate it with laser light L so that the surface roughness Ra is 0.6 μm or more and 1.8 μm or less.

[0115] The laser beam L is not particularly limited as long as it can deposit an Al layer 3 derived from the ceramic plate 1 at the irradiated area on the upper surface 1U of the ceramic plate 1, but a laser beam L capable of thermal processing is preferred. It is preferable that the Al layer 3 is formed continuously with the irradiated area on the upper surface 1U of the ceramic plate 1. At this time, the aluminum nitride contained in the ceramic plate 1 near the irradiated area on the upper surface 1U of the ceramic plate 1 forms irregularities, and the Al layer 3 is filled into these irregularities. This is because, when forming the Al layer 3, a rapid temperature increase occurs in the aluminum nitride due to irradiation with the laser beam L, causing a phase change in which a portion of the aluminum nitride melts and sublimes, resulting in ablation. Therefore, the ceramic plate 1 is not formed by creating irregularities on the upper surface 1U of the ceramic plate 1 using a physical processing method such as drilling, and then processing the surface 1A of the ceramic plate 1 where the Al layer 3 is placed so that it is rougher than the surface 1B of the ceramic plate 1 where the Al layer 3 is not placed, and then pouring molten aluminum into these irregularities to form the Al layer 3.

[0116] There are no particular restrictions on the pulse width of the laser light L, but it is preferable to include a continuous wave (CW). A continuous wave is defined as a laser light L with a pulse width that is maximized during the pulse repetition period.

[0117] Among these, the laser beam L capable of thermal processing preferably has a pulse width in the microsecond or nanosecond range, more preferably in the microsecond range, and even more preferably 1 microsecond or more and 23 microseconds or less.

[0118] Examples of laser light L capable of thermal processing include laser light having an oscillation wavelength of 2,000 nm or more, and laser light having an output of 500 W or more. For laser light having an oscillation wavelength of 2,000 nm or more, the oscillation wavelength is preferably 5,000 nm or more, and more preferably 10,000 nm or more.

[0119] Specific examples of laser beams L capable of thermal processing include Nd:YAG laser beams, Nd:YVO4 laser beams, fiber laser beams, CO2 laser beams, and disk laser beams. These may be used individually or in combination of two or more. Among these, CO2 laser beams are preferred as the laser beam L capable of thermal processing.

[0120] There are no particular restrictions on the atmospheric conditions when irradiating with laser light L; for example, a vacuum atmosphere or an inert gas atmosphere can be used. Examples of inert gases include N2 and CO2. These may be used individually or in combination of two or more.

[0121] In forming the Al layer (S10-2), it is preferable to irradiate the precipitated Al with laser light L so as not to oxidize it. There are no particular limitations on the method of irradiating with laser light L so as not to oxidize the precipitated Al; for example, irradiating with laser light L in an inert gas atmosphere is one such method.

[0122] There are no particular restrictions on the pulse width, power output, and wavelength of the laser light L that can be used for thermal processing. For example, processing can be performed using CO2 laser light (pulse: 10 microseconds x 1, wavelength: 10,096 nm, 2.5 kHz, 4 mJ), but the only requirement is that the Al layer 3 is deposited, and the process is not limited to these conditions.

[0123] By irradiating a predetermined area of ​​the upper surface 1U of the ceramic plate 1 with laser light L in the Z-axis direction and performing thermal processing, the ceramics on the surface 1A of the upper surface 1U of the ceramic plate 1 are removed mainly by melting and sublimation in the irradiated area that absorbed the irradiated laser light L. At this time, an Al layer 3 is deposited in the area of ​​the ceramic plate 1 irradiated with laser light L. The Al layer 3 may be formed by a single irradiation with laser light L, or it may be formed by gradually removing the ceramics by irradiating with laser light L multiple times, but it is preferable to irradiate the same location with laser light L only once. If the same location is irradiated with laser light L two or more times, after aluminum has been deposited by the first irradiation with laser light L, if the same location is irradiated with laser light again, all or part of the deposited aluminum may be remelted, and part of it may become aluminum oxide.

[0124] In a ceramic plate 1 irradiated with laser light L, the heat generated by the irradiation of the laser light L spreads not only to the irradiated area but also to the surrounding area. Therefore, the deposition of the Al layer 3 from the ceramic plate 1 occurs not only at the irradiated area but also in the surrounding area inside the ceramic plate 1 in the Z-axis direction from the irradiated area. Consequently, the thickness of the Al layer 3 can be adjusted by adjusting the pulse width, output, wavelength, etc., of the laser light L.

[0125] In forming the Al layer S10-2, when viewing a cross-section of the Al layer 3 in the thickness direction (Z-axis direction), let Lz be the horizontal length (X-axis or Y-axis direction) between one end 3A of the Al layer 3 and the other end 3B of the Al layer 3, let Pc be the position Lz / 5 from one end 3A toward the center of the Al layer 3 in the horizontal direction (X-axis or Y-axis direction), and let Pd be the position Lz / 5 from the other end 3B toward the center of the Al layer 3 in the horizontal direction (X-axis or Y-axis direction), it is preferable to irradiate the Al layer with laser light L such that the average thickness of the Al layer in the region between Pc and Pd is 0.2 μm or more and 5 μm or less, and it is more preferable to irradiate the Al layer with laser light L such that the average thickness is 0.5 μm or more and 1.0 μm or less.

[0126] (S10-3) Forming a metal layer Figure 9D is a schematic cross-sectional view showing an example of forming a metal layer in the manufacturing method of a ceramic substrate according to the first embodiment.

[0127] Forming a metal layer S10-3 involves plating the inside of the through-holes 51 of the first resist layer 50 and the upper surface of the Al layer 3 with one or more metals selected from the group consisting of Zn, Ni, and Cu to form a metal layer 4 with a minimum thickness of 18 μm or more.

[0128] The minimum thickness of the metal layer 4 is the minimum thickness of the metal layer 4 in the region between Pa and Pb, where Lw is the horizontal length between one end 4A and the other end 4B of the metal layer 4 in a cross-sectional view, Pa is the position Lw / 5 from one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4.

[0129] In forming the metal layer S10-3, the thickness of the metal layer 4 can be adjusted by the amount of plating solution containing one or more metals selected from the group consisting of Zn, Ni, and Cu that is applied.

[0130] The plating solution includes, for example, one or more metal particles selected from the group consisting of Zn, Ni, and Cu, and a solvent, and may also contain a resin or the like as needed. The plating solution is bonded to the ceramic plate 1.

[0131] (S10-4) Remove the first resist layer. Figure 9E is a schematic cross-sectional view showing an example of removing the first resist layer in the manufacturing method of a ceramic substrate according to the first embodiment. Figure 9F is an enlarged cross-sectional view of region IXF in Figure 9E.

[0132] Removing the first resist layer S10-4 involves removing the first resist layer 50.

[0133] In step S10-4, where the first resist layer is removed, it is preferable that the first resist layer 50 is completely removed. This forms a laminated structure of the ceramic plate 1, the Al layer 3, and the metal layer 4 having a predetermined shape.

[0134] The first resist layer 50 can be removed, for example, by the lift-off method. A solvent such as a stripping agent can be used in the lift-off method. For example, the first resist layer 50 can be removed by ultrasonic cleaning.

[0135] In step S10-4, when the first resist layer is removed, the outer angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4 in a cross-sectional view in the thickness direction (Z-axis direction) of the ceramic plate 1 can be adjusted by the shape of the side surface of the through hole 51 in the first resist layer 50 after irradiation of the first resist layer 50 with laser light L in step S10-2, when the Al layer is formed. There are no particular restrictions on the outer angle R between the upper surface 1U of the ceramic plate 1 and the side surface of the metal layer 4 in a cross-sectional view in the thickness direction (Z-axis direction) of the ceramic plate 1, but it is preferably 85° or more and 95° or less, and more preferably 88° or more and 92° or less.

[0136] (S10-5) Forming an Au layer Figure 9G is a schematic cross-sectional view showing an example of forming an Au layer in the manufacturing method of a ceramic substrate according to the first embodiment.

[0137] Forming the Au layer S10-5 involves forming the Au layer 5 on the top surface and side surface of the metal layer 4. Specifically, the Au layer 5 can be formed by applying the Au layer 5 material from above and from the side of the metal layer 4. The thickness of the Au layer 5 can be adjusted by the amount of Au layer 5 material applied.

[0138] The Au layer 5 can be formed by methods known in the field, such as electroplating, electroless plating, vapor deposition, and sputtering.

[0139] (S20) Form a heat dissipation section. Figure 9H is a schematic cross-sectional view showing an example of forming a heat dissipation section in the manufacturing method of a ceramic substrate according to the first embodiment.

[0140] Forming a heat dissipation section S20 means forming a heat dissipation section 10 on the lower surface 1L of the ceramic plate 1. There are no particular restrictions on the method of forming the heat dissipation section 10, and a known method can be appropriately selected.

[0141] There are no particular restrictions on the position where the heat dissipation section 10 is formed, but it is preferable that it be provided so as to overlap with the area directly below the first wiring section 2A in a horizontal plan view.

[0142] The first embodiment of the method for manufacturing a ceramic substrate comprises a ceramic plate 1 containing aluminum nitride and a first wiring portion 2A disposed on the upper surface 1U of the ceramic plate 1, wherein the first wiring portion 2A comprises an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer 5 disposed on the upper surface and side surface of the metal layer 4, and the surface of the ceramic plate 1 where the Al layer 3 is disposed Surface 1A is rougher than surface 1B of the ceramic plate 1 where the Al layer 3 is not present. In a cross-sectional view, if Lw is the horizontal length between one end 4A of the metal layer 4 and the other end 4B of the metal layer 4, Pa is the position Lw / 5 from one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4, then a ceramic substrate 100 is formed in which the minimum thickness of the metal layer 4 in the region between Pa and Pb is 18 μm or more.

[0143] The method for manufacturing a ceramic substrate according to the first embodiment is extremely low-cost because it can manufacture the ceramic substrate 100 with a small number of steps and without using expensive equipment such as photolithography or sputtering technology. Furthermore, since the metal layer 4 is formed by creating through holes 51 in the first resist layer 50 with laser light, the metal layer 4 can be formed in a desired shape, improving wiring precision. In addition, the Al layer 3 provides good adhesion between the ceramic plate 1 and the metal layer 4, improving connection reliability. Moreover, in the final ceramic substrate 100, the edge 3a of the upper surface of the Al layer 3 is located inside the edge 5b of the lower surface of the Au layer 5, so the upper surface 1U of the ceramic plate 1 and the lower surface of the Au layer 5 come into contact, completely covering the metal layer 4 and the Al layer 3 with the ceramic plate 1 and the Au layer 5. As a result, the metal layer 4 and the Al layer 3 are not affected by external environmental factors such as air, corrosion can be suppressed, and a more reliable ceramic substrate 100 can be obtained.

[0144] <Second Embodiment> The method for manufacturing a ceramic substrate according to the second embodiment is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that step S10-3, which involves forming a metal layer, is changed to step S11-3, which involves forming the following metal layer.

[0145] (S11-3) Forming a metal layer Forming a metal layer S11-3 involves plating the inside of the through-holes 51 of the first resist layer 50 and the upper surface of the Al layer 3 with one or more metals selected from the group consisting of Zn, Ni, and Cu to form a metal layer 4 with an average thickness of 20 μm or more.

[0146] The average thickness of the metal layer 4 is the average thickness of the metal layer 4 in the region between Pa and Pb, where Lw is the horizontal length between one end 4A and the other end 4B of the metal layer 4 in a cross-sectional view, Pa is the position Lw / 5 from one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4.

[0147] The method for manufacturing a ceramic substrate according to the second embodiment includes a ceramic plate 1 containing aluminum nitride and a first wiring portion 2A disposed on the upper surface 1U of the ceramic plate 1, wherein the first wiring portion 2A includes an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 and containing one or more metals selected from the group consisting of Zn, Ni, and Cu, and an Au layer 5 disposed on the upper surface and side surface of the metal layer 4, and the surface of the ceramic plate 1 where the Al layer 3 is disposed Surface 1A is rougher than surface 1B of the ceramic plate 1 where the Al layer 3 is not present. In a cross-sectional view, if Lw is the horizontal length between one end 4A of the metal layer 4 and the other end 4B of the metal layer 4, Pa is the position Lw / 5 from one end 4A toward the horizontal center of the metal layer 4, and Pb is the position Lw / 5 from the other end 4B toward the horizontal center of the metal layer 4, then a ceramic substrate 100 is formed in which the average thickness of the metal layer 4 in the region between Pa and Pb is 20 μm or more.

[0148] <Third Embodiment> The method for manufacturing a ceramic substrate according to the third embodiment is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that step S10-2, which involves forming an Al layer, is changed to step S12-2, which involves forming the following Al layer, and preferably, step S10-5, which involves forming an Au layer, is changed to step S12-5, which involves forming the following Au layer.

[0149] (S12-2) Forming an Al layer Figure 10A is a schematic cross-sectional view showing an example of forming an Al layer in the manufacturing method of a ceramic substrate according to the third embodiment.

[0150] Forming the Al layer S12-2 is the same as forming the Al layer S10-2 in the method for manufacturing a ceramic substrate according to the first embodiment, except that the laser beam L is irradiated such that the shortest distance Ln between the inner side surface of one through hole 51A of the first resist layer 50 and the inner side surface of another through hole 51B adjacent to the first through hole 51A is 10 μm or more and 50 μm or less.

[0151] The shortest distance Ln can be adjusted by the irradiation position of the laser beam L onto the first resist layer 50. One through hole 51A and the other through hole 51B may be formed simultaneously or separately.

[0152] (S12-5) Forming an Au layer Figure 10B is a schematic cross-sectional view showing an example of forming a metal layer and an Au layer in a method for manufacturing a ceramic substrate according to the third embodiment.

[0153] Forming the Au layer S12-5 is the same as forming the Au layer S10-5 in the method for manufacturing a ceramic substrate according to the first embodiment, except that the shortest distance Lm between the side surface of the Au layer 5 in one first wiring portion 2A1 and the side surface of the Au layer 5 in another first wiring portion 2A2 adjacent to the first first wiring portion 2A1 is 10 μm or more and 100 μm or less, preferably 50 μm or more and 80 μm or less.

[0154] The shortest distance Lm can be adjusted by the size of the metal layer 4, the thickness of the Au layer, etc. The Au layer 5 in one first wiring section 2A1 and the Au layer 5 in the other first wiring section 2A2 may be formed simultaneously or separately.

[0155] <Fourth Embodiment> The method for manufacturing a ceramic substrate according to the fourth embodiment is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that forming an Al layer (S10-2), forming a metal layer 4 (S10-3), and forming an Au layer (S10-5) in the method for manufacturing a ceramic substrate according to the first embodiment are changed to forming an Al layer (S13-2), forming a metal layer 4 (S13-3), and forming an Au layer (S13-5), respectively.

[0156] (S13-2) Forming an Al layer Figure 11A is a schematic cross-sectional view showing an example of forming an Al layer in the manufacturing method of a ceramic substrate according to the fourth embodiment. Figure 11B is an enlarged view of region XIB in Figure 11A.

[0157] Forming the Au layer S13-2 is the same as forming the Al layer S10-2 in the manufacturing method of the ceramic substrate according to the first embodiment, except that, in a cross-sectional view of the ceramic substrate 100 in the thickness direction (Z-axis direction), the first resist layer 50 is irradiated with laser light L such that the aperture is wide in the aperture direction.

[0158] The aperture direction is the direction of irradiation of the laser light L. Therefore, in terms of the thickness of the first resist layer 50, being wide in the aperture direction means that in the thickness direction (Z-axis direction) of the first resist layer 50, the aperture widens from the upper surface of the first resist layer 50 toward the lower surface of the first resist layer 50 (the surface in contact with the ceramic plate 1). In other words, the width (length in the X-axis direction) of the cross-sectional view of the first resist layer 50 decreases from the upper surface toward the lower surface of the first resist layer 50. Such a cross-sectional shape of the through hole 51 is also called an overhang shape or an inverse taper shape.

[0159] By forming the Au layer S13-2, the first resist layer 50 is formed such that its cross-sectional shape in the thickness direction (Z-axis direction) has a main portion 50A of the first resist layer that is in contact with region M on the surface 1B of the upper surface 1U of the ceramic plate 1, and a protruding portion 50B that extends from the main portion 50A onto region N without being in contact with region N on the surface of the Al layer 3 on the surface 1A of the upper surface 1U of the ceramic plate 1 adjacent to region M. As a result, a space S is formed between the Al layer 3 and the lower surface of the protruding portion 50B.

[0160] (S13-3) Forming a metal layer Figure 11C is a schematic cross-sectional view showing an example of forming a metal layer in the manufacturing method of a ceramic substrate according to the fourth embodiment.

[0161] A metal layer 4 is formed by applying a plating solution containing one or more metals selected from the group consisting of Zn, Ni, and Cu to the Al layer 3 exposed from the first resist layer 50. At this time, the first resist layer 50 is located in the space S, so the plating solution is not applied there.

[0162] (S13-5) Forming an Au layer Figure 11D is a schematic cross-sectional view showing an example of forming an Au layer in the manufacturing method of a ceramic substrate according to the fourth embodiment. Figure 11E is a schematic top view of the ceramic substrate according to the fourth embodiment.

[0163] In forming the Au layer S13-5, in a plan view in the horizontal direction (X-axis or Y-axis direction), the upper edge 3a of the Al layer 3 is outside the lower edge 4b ​​of the metal layer 4, and the upper edge 3a of the Al layer 3 is inside the lower edge 5b of the Au layer 5.

[0164] <Fifth Embodiment> Figure 12 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the fifth embodiment. The method for manufacturing a ceramic substrate according to the fifth embodiment further includes forming the following intermediate layer S14-4 between forming a metal layer S14-3 and removing the first resist layer S14-5, and is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that forming the Au layer S10-5 in the method for manufacturing a ceramic substrate according to the first embodiment is changed to forming the following Au layer S14-6.

[0165] (S14-4) Forming an intermediate layer Figure 13A is a schematic cross-sectional view showing an example of forming an intermediate layer in the method for manufacturing a ceramic substrate according to the fifth embodiment.

[0166] In forming the intermediate layer S14-4, after removing the first resist layer 50, one intermediate layer 6 is formed on the upper surface and side surface of the metal layer 4.

[0167] (S14-6) Forming an Au layer Figure 13B is a schematic cross-sectional view showing an example of forming an Au layer in the manufacturing method of a ceramic substrate according to the fifth embodiment.

[0168] In forming the Au layer S14-6, the Au layer 5 is formed on the upper surface and the side surface of the intermediate layer 6.

[0169] A ceramic substrate 100 is formed by a method for manufacturing a ceramic substrate according to the fifth embodiment, which includes a ceramic plate 1 containing aluminum nitride and a first wiring portion 2A disposed on the upper surface 1U of the ceramic plate 1, wherein the first wiring portion 2A includes an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 and containing one or more metals selected from the group consisting of Zn, Ni, and Cu, a single intermediate layer 6 disposed on the upper surface and side surface of the metal layer 4, and an Au layer 5 disposed on the upper surface and side surface of the intermediate layer 6.

[0170] <Sixth Embodiment> Figure 14 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the sixth embodiment. The method for manufacturing a ceramic substrate according to the sixth embodiment is the same as the method for manufacturing a ceramic substrate according to the fifth embodiment, except that forming an intermediate layer (S14-4) is changed to forming a first intermediate layer (S15-4) and a second intermediate layer (S15-5), and forming an Au layer (S14-6) is changed to forming an Au layer (S15-7).

[0171] (S15-4) Forming the first intermediate layer Figure 15A is a schematic cross-sectional view showing an example of forming a first intermediate layer in the manufacturing method of a ceramic substrate according to the sixth embodiment.

[0172] In forming the first intermediate layer S15-4, after removing the first resist layer 50, the first intermediate layer 6-1 is formed on the upper surface and side surface of the metal layer 4.

[0173] (S15-5) Forming a second intermediate layer Figure 15B is a schematic cross-sectional view showing an example of forming a second intermediate layer in the manufacturing method of a ceramic substrate according to the sixth embodiment.

[0174] In forming the second intermediate layer S15-4, the second intermediate layer 6-2 is formed on the upper surface and the side surface of the first intermediate layer 6-1.

[0175] (S15-7) Forming an Au layer Figure 15C is a schematic cross-sectional view showing an example of forming an Au layer in the manufacturing method of a ceramic substrate according to the sixth embodiment.

[0176] In forming the Au layer S15-7, the Au layer 5 is formed on the upper surface and the side surface of the second intermediate layer 6-2.

[0177] A ceramic substrate 100 is formed by a method for manufacturing a ceramic substrate according to the sixth embodiment, which includes a ceramic plate 1 containing aluminum nitride and a first wiring portion 2A disposed on the upper surface 1U of the ceramic plate 1, wherein the first wiring portion 2A includes an Al layer 3 disposed on the upper surface 1U of the ceramic plate 1, a metal layer 4 disposed on the upper surface of the Al layer 3 and containing one or more metals selected from the group consisting of Zn, Ni, and Cu, a first intermediate layer 6-1 disposed on the upper surface and side surface of the metal layer 4, a second intermediate layer 6-2 disposed on the upper surface and side surface of the first intermediate layer 6-1, and an Au layer 5 disposed on the upper surface and side surface of the second intermediate layer 6-2.

[0178] <Seventh Embodiment> Figure 16 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the seventh embodiment. The method for manufacturing a ceramic substrate according to the seventh embodiment is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that it further includes polishing or grinding S16-4 between forming a metal layer S16-3 and removing the first resist layer S16-5.

[0179] (S16-4) Polishing or grinding Polishing or grinding S16-4 involves polishing or grinding the upper surface of the first resist layer 50 and the upper surface of the metal layer 4 after forming the metal layer S16-3. If the upper surface of the Al layer 3 is roughened and has irregularities during the formation of the Al layer S16-2, irregularities may also occur on the upper surface of the metal layer 4. In addition, irregularities and burrs may occur due to uneven plating. By including polishing or grinding S16-4, the upper surface of the metal layer 4 can be smoothed, improving the adhesion between the metal layer 4 and the Au layer 5.

[0180] <Eighth Embodiment> Figure 17 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the eighth embodiment. The method for manufacturing a ceramic substrate according to the eighth embodiment is the same as the method for manufacturing a ceramic substrate according to the first embodiment, except that it further includes forming a second wiring section in S30 after forming the Au layer in S17-5.

[0181] (S30) Forming the second wiring section Forming the second wiring section S30 includes placing the first resist layer S30-1, forming an Al layer S30-2, forming a metal layer S30-3, removing the first resist layer S30-4, and forming an Au layer S30-5. Placing the first resist layer S30-1 is the same as forming the first wiring section S10, except that the first resist layer 50 is provided on the lower surface 1L of the ceramic plate 1 containing aluminum nitride.

[0182] Figure 18 is a schematic cross-sectional view of a ceramic substrate 100 manufactured by forming a second wiring section in the manufacturing method of a ceramic substrate according to the eighth embodiment.

[0183] [Light-emitting device] Figure 19A is a schematic top view showing an example of a light-emitting device according to the embodiment. Figure 19B is a schematic cross-sectional view in the stacking direction along the line XIXB-XIXB in Figure 19A. Figure 19C is an enlarged cross-sectional view of region XIXC in Figure 19B. The various components of the light-emitting device 200 will be described below.

[0184] The light-emitting device 200 according to the embodiment includes a ceramic substrate 100 according to the embodiment and a light-emitting element 20 disposed on the ceramic substrate 100. The light-emitting device 200 according to the embodiment further includes a reflective member 40 disposed on the upper surface 1U of the ceramic substrate 100, and it is preferable that the reflective member 40 is in contact with the surface 1B of the upper surface 1U of the ceramic plate 1 that is exposed from the Au layer 5 and the first wiring portion 2A. The light-emitting device 200 according to the embodiment may also include a bonding member 60 for electrically connecting the light-emitting element 20 and the ceramic substrate 100, a light-transmitting member 30 disposed on the upper surface of the light-emitting element 20, and a frame 41 surrounding the light-emitting element 20 on the ceramic substrate 100.

[0185] The light-emitting device 200 is a device that emits light by placing a light-emitting element 20 on a ceramic substrate 100. In the light-emitting device 200, the first wiring section 2A of the ceramic substrate 100, in which the Al layer 3, metal layer 4, and Au layer 5 are laminated, serves as an element mounting region on which the light-emitting element 20 is placed.

[0186] Furthermore, in the light-emitting device 200, the pad portion 12 of the ceramic substrate 100 serves as an external connection area to ensure electrical connection with the outside of the light-emitting device 200. The pad portion 12 is located outside the frame 41. In a plan view of the light-emitting device 200, the boundary between the first wiring portion 2A and the pad portion 12 is located inside the outer edge of the frame 41.

[0187] The frame 41 has a substantially rectangular shape in plan view, and three sides of the rectangle are formed to cover the first wiring section 2A or the pad section 12.

[0188] Since the light-emitting device 200 has a ceramic substrate 100, a wiring layer made of a different material can be arranged in the element mounting area (first wiring section 2A) and in the external connection area (pad section 12). This allows the element mounting area to have a wiring layer suitable for bonding with the light-emitting element 20, and the external connection area to have a wiring layer suitable for bonding with an external power supply member. As a result, the bonding between the light-emitting element 20 and the ceramic substrate 100, and the bonding between the external power supply member and the ceramic substrate 100, can be made stronger and more reliable.

[0189] (Light-emitting element 20) The light-emitting element 20 is preferably a light-emitting diode. There are no particular restrictions on the composition of the light-emitting element 20, and any composition can be used depending on the desired emission wavelength. For example, a nitride semiconductor (In) capable of emitting blue or green light. x Al y Ga 1-x-y N, 0≦X, 0≦Y, X+Y≦1) or GaP, or GaAlAs or AlInGaP capable of emitting red light can be used. These may be used individually or in combination of two or more. Furthermore, the dimensions and shape of the light-emitting element 20 can be appropriately selected depending on the purpose of use.

[0190] The light-emitting element 20 is typically formed by laminating semiconductor layers on a support substrate (for example, a translucent substrate such as sapphire). The support substrate may have irregularities on the bonding surface with the semiconductor layer. This allows for an intentional change in the critical angle when light emitted from the semiconductor layer strikes the substrate, making it easy to extract light to the outside of the support substrate. The support substrate may be removed after the semiconductor layers have been laminated. Removal can be performed, for example, by polishing or LLO (Laser Lift Off).

[0191] The light-emitting element 20 is face-down mounted so that it has a positive and negative pair of electrodes on the side that contacts the ceramic substrate 100. The electrodes are electrically connected to the first wiring section 2A of the ceramic substrate 100.

[0192] When the light-emitting element 20 is mounted face-down, the light-emitting element 20 can be flip-chip mounted on the mounting substrate. In this case, the surface of the light-emitting element 20 opposite to the surface on which the pair of electrodes are formed becomes the main light extraction surface. In flip-chip mounting, the light-emitting element 20 and the first wiring section 2A of the ceramic substrate 100 are electrically connected using a conductive paste-like bonding member such as solder, a thin film bonding member, or a bump-shaped bonding member.

[0193] The positive and negative electrodes of the light-emitting element 20 preferably have an outermost surface made of Au. Au is chemically stable and can ensure long-term reliability of the electrical connection. Furthermore, since the outermost surface of the first wiring section 2A of the ceramic substrate is an Au layer 5, a more reliable connection can be achieved by making the outermost surface of the positive and negative electrodes of the light-emitting element 20 the same material as the Au layer 5 of the first wiring section 2A.

[0194] The number of light-emitting elements 20 may be one or multiple. Furthermore, if there are multiple light-emitting elements 20, there are no particular restrictions on their arrangement; for example, they may be arranged in a line in the first direction or in a matrix. When the light-emitting device 200 has a horizontally elongated light distribution pattern suitable for vehicle headlights, it is preferable to arrange them in a line in the first direction. For example, if the horizontal planar shape of the ceramic substrate 100 is rectangular, the direction in which the longer side extends is considered the first direction, and it is preferable to arrange multiple light-emitting elements 20 in a line along the first direction, and it is more preferable to arrange multiple light-emitting elements 20 in a line at equal intervals along the first direction.

[0195] The light-emitting element 20 is placed on the first wiring portion 2A of the ceramic substrate 100. The first wiring portion 2A is located inside the frame 41 and is joined to the light-emitting element 20. However, the first wiring portion 2A includes not only the joint portion with the light-emitting element 20 but also the surrounding area.

[0196] There are no particular restrictions on the horizontal planar shape of the light-emitting element 20, and it can be a variety of shapes such as a circle, ellipse, square, hexagon, polygons with rounded corners, or a combination of these shapes. Among these, a square is preferred, and a rectangle is more preferred. This allows multiple light-emitting elements 20 to be arranged in the first direction while keeping the distance between the sides of adjacent light-emitting elements 20 constant, so that the multiple light-emitting elements 20 are arranged in close proximity. As a result, a horizontally elongated rectangular light-emitting surface can be formed in planar view in the horizontal direction.

[0197] The vertical, horizontal, and height dimensions of the light-emitting element 20 can be set arbitrarily. Among these, it is preferable to use a larger light-emitting element 20 in order to realize a higher-output light-emitting device 200, and in a plan view in the horizontal direction of the light-emitting element 20, the vertical and horizontal dimensions of the light-emitting element 20 are preferably 600 μm or more, and more preferably 1,000 μm or more. Furthermore, from the viewpoint of uniformity of light emission intensity and ease of mounting, it is preferable that the vertical and horizontal dimensions of the light-emitting element 20 are 2,000 μm or less.

[0198] The light-emitting elements 20 are arranged at a distance from adjacent light-emitting elements 20. In this case, the distance between the light-emitting elements 20 can be, for example, in the range of 0.1 to 0.5 times the length of one side of the light-emitting element 20 along the first direction. Specifically, when using a light-emitting element 20 with a roughly square shape in plan view and a length and width dimension of approximately 1,000 μm, the distance between adjacent light-emitting elements 20 can be in the range of 100 μm to 500 μm.

[0199] (Jointing member 60) The light-emitting element 20 is typically mounted onto the ceramic substrate 100 via a bonding member 60. Examples of bonding members 60 include solders such as Sn-Bi, Sn-Cu, Sn-Ag, and Au-Sn; 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; conductive pastes such as Ag, Au, and Pd; bumps; anisotropic conductive materials such as anisotropic conductive films (ACF) and anisotropic conductive pastes (ACP); brazing materials of low-melting-point metals; and conductive adhesives and conductive composite adhesives that combine these materials. These may be used individually or in combination of two or more. Among these, it is preferable that the light-emitting element 20 is mounted on the first wiring section 2A by a bonding member 60 containing Au. Since the outermost surface of the first wiring section 2A is the Au layer 5, using a bonding member containing Au ensures a more reliable and stable connection over a long period of time.

[0200] (Reflective member 40) The reflective member 40 is a member that has light reflectivity. Preferably, the reflective member 40 is placed on the upper surface of the ceramic substrate 100 and is in contact with the surface 1B of the upper surface 1U of the ceramic plate 1 and the Au layer 5. Preferably, the reflective member 40 is also placed so as to cover the side surface of the light-emitting element 20. In the light-emitting device 200, as an example, the reflective member 40 is also placed between the lower surface of the light-emitting element 20 and the upper surface of the ceramic substrate 100. By placing the reflective member 40 on the upper surface of the ceramic substrate 100 and in contact with the surface 1B of the upper surface 1U of the ceramic plate 1 and the Au layer 5, lifting (peeling) of the reflective member can be suppressed.

[0201] The reflective member 40 preferably has a high reflectivity in order to effectively utilize the light from the light-emitting element 20. The reflective member 40 is preferably white. The reflectivity of the reflective member 40 is preferably 90% or more, and more preferably 94% or more, at the wavelength of light emitted by the light-emitting element 20.

[0202] The reflective member 40 can be formed using, for example, a resin material. Examples of resin materials include thermoplastic resins such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyester resin, or thermosetting resins such as epoxy resin or silicone resin.

[0203] Furthermore, it is preferable that the reflective member 40 contains a filler such as a light-reflective substance in the resin material. As the light-reflective substance, known materials such as titanium oxide, silicon oxide, zirconium oxide, aluminum oxide, zinc oxide, potassium titanate, aluminum nitride, boron nitride, and mullite can be used. The amount of light-reflective substance can be adjusted as appropriate according to the characteristics of the light-emitting device 200 to be obtained, as it can vary the amount of light reflected and transmitted by the reflective member 40, but it is preferable that it be 30% by mass or more of the total mass of the reflective member 40.

[0204] (Translucent member 30) The light-transmitting member 30 is preferably arranged on the light-extraction surface side of the light-emitting element 20 and is provided in conjunction with the light-extraction surface of the light-emitting element 20.

[0205] The light-transmitting member 30 has an upper surface and a lower surface. Light emitted from the light-emitting element 20 is incident on the lower surface of the light-transmitting member 30, and the upper surface of the light-transmitting member 30 acts as a light extraction surface, emitting the light to the outside from the upper surface of the light-transmitting member 30. Preferably, the light-transmitting member 30 is a member that transmits 60% or more of the light emitted from the light-emitting element 20.

[0206] The lower surface of the translucent member 30 preferably covers the entire upper surface of the light-emitting element 20 in order to efficiently extract the light emitted from the light-emitting element 20. In other words, in a horizontal plan view, it is preferable that the edge of the upper surface of the light-emitting element 20 is covered in a way that it is enclosed within the edge of the lower surface of the translucent member 30. Furthermore, it is preferable that the area of ​​the upper surface of the translucent member 30 is smaller than the sum of the areas of the upper surfaces of the multiple light-emitting elements 20 provided by the light-emitting device 200. This allows the light emitted from the light-emitting element 20, which is incident from the lower surface of the translucent member 30, to be emitted from the upper surface of the translucent member 30 (i.e., the light-emitting surface of the light-emitting device 200), which has a smaller area. In other words, the light-emitting device 200 becomes brighter because the light emitted from the light-emitting element 20 is focused by the translucent member 30, and it becomes possible to illuminate further distances.

[0207] The light-transmitting member 30 may cover each of the multiple light-emitting elements 20 individually, or it may cover the multiple light-emitting elements 20 integrally. Preferably, the outer peripheral surface of the light-transmitting member 30 is covered by the reflective member 40.

[0208] There are no particular restrictions on the thickness of the light-transmitting member 30, but it is preferably 50 μm or more and 300 μm or less.

[0209] When a single light-emitting device 200 comprises multiple translucent members 30, it is preferable that the upper surfaces of the multiple translucent members 30 be flush or substantially flush. This makes it possible to more reliably prevent interference between the light emitted from the sides of the translucent members 30. On the other hand, regardless of the number, the upper surfaces of the translucent members 30 may have various shapes, such as uneven surfaces, curved surfaces, or lens-like surfaces. It is preferable that the lower surface of the translucent member 30 be a surface parallel to the light-emitting surface of the light-emitting element 20.

[0210] The light-transmissive member 30 can be formed, for example, from a light-diffusing material or a material containing a phosphor capable of wavelength-converting at least a part of the light incident from the light-emitting element 20. Examples of the light-transmissive member 30 containing a phosphor include, for example, a sintered body of a phosphor; a material in which phosphor powder is contained in a resin, glass, or other inorganic substance. The sintered body of the phosphor may be formed by sintering only the phosphor, or may be formed by sintering a mixture of the phosphor and a sintering aid. When sintering a mixture of the phosphor and a sintering aid, it is preferable to use an inorganic material such as silicon oxide, aluminum oxide, or titanium oxide as the sintering aid. Thereby, even if the light-emitting element 20 has a high output, discoloration or deformation of the sintering aid due to light or heat can be suppressed. The higher the light transmittance of the light-transmissive member 30, the easier it is to reflect light at the interface with the reflecting member 40, so that the luminance can be improved.

[0211] As the phosphor to be contained in the light-transmissive member 30, a phosphor that can be excited by the light emitted from the light-emitting element 20 is used. For example, one of the following specific examples can be used alone, or two or more of them can be used in combination. Specific examples of phosphors that can be excited by a blue light-emitting element or an ultraviolet light-emitting element include yttrium aluminum garnet-based phosphors activated with cerium (for example, Y3(Al,Ga)5O 12 :Ce), lutetium aluminum garnet-based phosphors activated with cerium (for example, Lu3(Al,Ga)5O 12 :Ce), nitrogen-containing calcium aluminosilicate-based phosphors activated with europium and / or chromium (for example, CaO-Al2O3-SiO2:Eu), terbium aluminum garnet-based phosphors (for example, Tb3(Al,Ga)5O 12 :Ce), silicate-based phosphors activated with europium (for example, (Sr,Ba)2SiO4:Eu), β-sialon-based phosphors (for example, Si 6-z Al z O z N 8-z :Eu(0<Z<4.2)), α-sialon-based phosphors (for example, Mz(Si,Al) 12 (O,N) 16(However, 0 < z ≤ 2, and M is a lanthanide element excluding Li, Mg, Ca, Y, and La and Ce), nitride-based phosphors such as CASN-based phosphors (e.g., CaAlSiN3:Eu), SCASN-based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), manganese-activated potassium fluorosilicate-based phosphors (e.g., K2SiF6:Mn, K2(Si,Al)F6:Mn, 3.5MgO·0.5MgF2·GeO2:Mn), sulfide-based phosphors, quantum dot phosphors (e.g., perovskite, chalcopyrite), etc. can be mentioned. By combining these phosphors with a blue light-emitting element or an ultraviolet light-emitting element, various color light-emitting devices (e.g., white light-emitting devices) can be manufactured. When making a light-emitting device that can emit white light, it is adjusted to be white according to the type and concentration of the phosphor contained in the light-transmissive member 30. When such a phosphor is contained in the light-transmissive member 30, it is preferable to set the concentration of the phosphor to about 5% or more and 50% or less.

[0212] The light-transmissive member 30 and the light extraction surface of the light-emitting element 20 can be joined, for example, via a light guide member 61. Also, for the joining of the light-transmissive member 30 and the light-emitting element 20, direct joining by pressure bonding, sintering, surface activation bonding, atomic diffusion bonding, or hydroxyl bonding may be used without using the light guide member 61.

[0213] The light-transmissive member 30 is usually disposed on the upper surface of the light-emitting element 20, but depending on its form, it may cover a part on the first wiring portion 2A and / or a part on the pad portion 12.

[0214] (Frame body 41) The frame body 41 is disposed to surround the light-emitting element 20 on the ceramic substrate 100. In a plan view in the horizontal direction, it is preferable that the outer edge of the frame body 41 includes the boundary between the first wiring portion 2A and the pad portion 12. Thereby, the frame body 41 covers the step between the first wiring portion 2A and the pad portion 12, the contact area with the frame body 41 becomes large, and the anchor effect due to the step can be exerted.

[0215] The frame 41 is positioned spaced apart from the outer edge of the upper surface of the ceramic substrate 100. This ensures that, during the manufacturing process of the light-emitting device 200, the frame 41 and reflective members 40 are not positioned on the fragmentation line when the assembly of light-emitting devices 200 is separated into individual light-emitting devices 200. In other words, the resin members are not cut during fragmentation, thus suppressing changes in the shape of the resin members due to stress during cutting and peeling from the ceramic substrate 100.

[0216] The frame 41 is made of an insulating material to cover the first wiring section 2A and a portion of the pad section 12. The frame 41 can be made, for example, using an insulating resin material. Examples of insulating resin materials include silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, acrylic resin, or hybrid resins containing at least one of these resins. These may be used individually or in combination of two or more.

[0217] The frame 41 can contain a filler such as a light-reflective material in an insulating resin material. The same light-reflective material as the one in the reflective member 40 can be used.

[0218] Furthermore, when the frame 41 is positioned to be in contact with the first wiring section 2A, it is preferable that the first wiring section 2A has grooves or holes 62 on the surface of the area in contact with the frame 41. It is preferable that the ceramic plate 1 is exposed at the bottom of the grooves or holes 62. This improves the adhesion between the frame 41 and the ceramic substrate 100, resulting in a more reliable light-emitting device 200.

[0219] (Other components) The light-emitting device 200 may be equipped with other elements such as a protective element 42, electronic components, etc. Preferably, these other elements and electronic components are embedded in the reflective member 40.

[0220] Furthermore, the light-emitting device 200 may be provided with a recognition mark 14 on its upper surface. The recognition mark 14 is provided between one side of the outer edge of the substantially rectangular ceramic substrate 100 where the first wiring section 2A and the pad section 12 do not extend, and the outer edge of the frame 41. The recognition mark 14 can be used for position recognition of the light-emitting surface of the light-emitting device 200 when the light-emitting device 200 is secondary mounted, or for position recognition when forming the frame 41 in the manufacturing process. The recognition mark 14 can be formed, for example, using the same metal material as the pad section 12. By using the same material for the surface of the pad section 12 and the recognition mark 14, corrosion of the metal due to the potential difference between different metal materials can be suppressed.

[0221] [Method for manufacturing a light-emitting device] A method for manufacturing a light-emitting device according to an embodiment includes preparing a ceramic substrate 100 according to the embodiment, arranging a light-emitting element 20 on the ceramic substrate 100, and electrically connecting the electrode and the first wiring section 2A. Preferably, a method for manufacturing a light-emitting device according to an embodiment further includes arranging a reflective member 40 on the upper surface of the ceramic substrate 100.

[0222] Figure 20 is a flowchart showing an example of a method for manufacturing a light-emitting device according to an embodiment.

[0223] (S40) Prepare the ceramic substrate. In step S40, preparing the ceramic substrate 100, the ceramic substrate 100 according to the embodiment is prepared.

[0224] Furthermore, the ceramic substrate 100 may have multiple areas for arranging the light-emitting elements 20, and after arranging the reflective members 40, it may be made into pieces of a size suitable for each light-emitting device 200, or it may be made to the size of each individual light-emitting device 200.

[0225] (S41) Arrange the light-emitting element. In the placement of the light-emitting element S41, the light-emitting element 20 is placed on the ceramic substrate 100. In the placement of the light-emitting element S41, it is preferable to electrically connect the electrodes of the light-emitting element 20 to the upper surface of the first wiring section 2A using a bonding member 60. It is preferable that the light-emitting element 20 is placed with the translucent member 30 already connected to it. When bonding the translucent member 30 to the light-emitting element 20, a translucent bonding material is preferably used.

[0226] (S42) Arrange reflective material In step S42, the reflective member 40 is placed on the upper surface of the ceramic substrate 100. At this time, the reflective member 40 is placed so as to be in contact with the Au layer 5 of the ceramic substrate 100 and the surface 1B of the upper surface 1U of the ceramic plate 1. This suppresses the lifting (peeling) of the reflective member. Furthermore, in step S42, it is preferable to place the reflective member 40 so as to cover the side surface of the light-emitting element 20. The reflective member 40 is placed on the ceramic substrate 100 so as to surround the light-emitting element 20 and expose the upper surface of the translucent member 30 placed on the light-extracting surface of the light-emitting element 20. It is preferable that the reflective member 40 is placed so as to be rectangular in plan view.

[0227] In the manufacturing method of the light-emitting device according to the embodiment, after arranging the reflective members in S42, individualization work is performed as needed. One unit of the light-emitting device 200 is predetermined by the number of light-emitting elements 20 used. Therefore, when multiple light-emitting devices 200 are manufactured together, individualization work is performed. When individualization work is performed, multiple light-emitting devices 200 are produced by cutting in a grid pattern. Examples of cutting methods include using a disc-shaped rotating blade, an ultrasonic cutter, a laser beam irradiation blade, etc. [Examples]

[0228] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way to these examples.

[0229] (Example 1) A ceramic substrate 100 was manufactured based on the flowchart of the first embodiment shown in Figure 8. Specifically, in S10-1, the first resist layer was placed using a ceramic plate 1 made of sintered ceramics, and the first resist layer 50, which is a dry film formed from a negative-type photoresist composition, was placed on the upper surface 1U of the ceramic plate 1. Next, in S10-2, the Al layer was formed using a CO2 laser in an atmospheric environment under the conditions of pulse: 10 microseconds × 1, wavelength: 10,096 nm, 2.5 kHz, and 4 mj. This formed an Al layer 3 with an average thickness of 2 μm in the region between Pc and Pd. Next, in S10-3, the metal layer was formed, and a metal layer 4 with a minimum thickness of 18 μm in the region between Pa and Pb was formed. Next, in S10-5, the Au layer 5 was formed by electroplating. Next, in forming the heat dissipation section S20, the heat dissipation section 10 was formed on the lower surface 1L of the ceramic plate 1, and the ceramic substrate 100 was formed.

[0230] (Reference example 1) A ceramic substrate 100 was manufactured based on the flowchart of the first embodiment shown in Figure 8. Similar to Example 1, a first resist layer 50 was placed on the ceramic plate 1. Next, the Al layer was formed (S10-2) using a CO2 laser under atmospheric conditions: pulse: 5 microseconds x 4 times, wavelength: 10,096 nm, 2.5 kHz, 2 mJ. Under these conditions, oxidation of the Al layer was observed on the surface. This formed an Al layer 3 containing aluminum oxide Al2O3 with an average thickness of 2 μm in the region between Pc and Pd. Subsequent steps were carried out in the same manner as in Example 1.

[0231] For Example 1 and Reference Example 1, a horizontal plan view of the intermediate ceramic substrate 100 obtained in step S10-5, where the Au layer is formed in the manufacturing method of the ceramic substrate according to the first embodiment, was observed from above at 20x magnification. Figure 21A is a photograph of Example 1. Figure 21B is a photograph of Reference Example 1.

[0232] When performing the laser irradiation on the same location once to form the Al layer (Example 1) and comparing it with the case of performing the laser irradiation four times (Reference Example 1), it was found that the Al layer 3 was oxidized in the case of performing the laser irradiation four times. This is presumably because after the laser irradiation is performed and aluminum is deposited, when the laser irradiation is performed again on the same location, all or part of the deposited aluminum melts again, and part of it becomes aluminum oxide. Therefore, it is preferable that the laser irradiation on the same location be performed once.

[0233] As described above, the present invention has been described based on specific embodiments, but these are merely presented as examples, and the present invention is not limited by the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, replacements, additions, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

[0234] In addition to the above embodiments, the following supplementary notes are further disclosed. (Supplementary Note 1) A ceramic plate containing aluminum nitride, A first wiring portion disposed on the upper surface of the ceramic plate, having, The first wiring portion, an Al layer disposed on the upper surface of the ceramic plate, a metal layer containing one or more metals selected from the group consisting of Zn, Ni, and Cu, disposed on the upper surface of the Al layer, an Au layer disposed on the upper surface and the side surface of the metal layer, having, In the ceramic plate, the surface of the ceramic plate at the location where the Al layer is disposed is rougher than the surface of the ceramic plate at the location where the Al layer is not disposed, In a cross-sectional view, when Lw is the horizontal length between one end of the metal layer and the other end of the metal layer, Pa is defined as the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is defined as the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer, the minimum thickness of the metal layer in the region between Pa and Pb is 18 μm or more, this is a ceramic substrate. (Note 2) A ceramic plate containing aluminum nitride, A first wiring section is arranged on the upper surface of the ceramic plate, It has, The first wiring section is, An Al layer is placed on the upper surface of the ceramic plate, A metal layer comprising one or more metals selected from the group consisting of Zn, Ni, and Cu, disposed on the upper surface of the Al layer, Au layers are disposed on the upper surface and the side surface of the metal layer, It has, In the ceramic plate, the surface of the ceramic plate in the area where the Al layer is placed is rougher than the surface of the ceramic plate in the area where the Al layer is not placed. In a cross-sectional view, when Lw is the horizontal length between one end of the metal layer and the other end of the metal layer, Pa is defined as the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is defined as the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer, the average thickness of the metal layer in the region between Pa and Pb is 20 μm or more, this is a ceramic substrate. (Note 3) The ceramic substrate is as described in Appendix 1 or Appendix 2, wherein, in a cross-sectional view in the thickness direction of the ceramic substrate, the angle of the outer angle between the upper surface of the ceramic plate and the side surface of the metal layer is 85° or more and 95° or less. (Note 4) The first wiring section has a plurality of parts, In a plurality of the aforementioned first wiring sections, the shortest distance between the side surface of the Au layer in one of the first wiring sections and the side surface of the Au layer in another first wiring section adjacent to the first first wiring section is 10 μm or more and 100 μm or less, as described in any one of the appendices 1 to 3. (Note 5) In a plan view, the area of ​​the metal layer is 100% or more and 105% or less of the area of ​​the Al layer, as described in Appendix 4. (Note 6) In a cross-sectional view, when Lz is the horizontal length between one end of the Al layer and the other end of the Al layer, Pc is the position Lz / 5 from one end of the Al layer toward the horizontal center of the Al layer, and Pd is the position Lz / 5 from the other end of the Al layer toward the horizontal center of the Al layer, the average thickness of the Al layer in the region between Pc and Pd is 0.2 μm or more and 5 μm or less, as described in any one of the appendices 1 to 5. (Note 7) In the horizontal direction, the edge of the upper surface of the Al layer is inward from the edge of the lower surface of the Au layer, as described in any one of the appendices 1 to 6. (Note 8) The side surface of the Al layer is covered by the Au layer. The ceramic substrate is one of the items described in any one of the appendices 1 to 7, wherein the upper surface of the ceramic plate and the lower surface of the Au layer are in contact. (Note 9) The ceramic substrate is one of the ceramic substrates described in any one of the appendices 1 to 8, wherein the surface roughness Ra of the ceramic plate in the area where the Al layer is arranged is 0.5 μm or more and 2.0 μm or less. (Note 10) The first wiring section is a ceramic substrate according to any one of the appendices 1 to 9, further comprising one or more intermediate layers disposed on the upper surface and side surfaces of the metal layer. (Note 11) The side surface of the Al layer is covered by the intermediate layer, The Au layer is arranged on the upper surface and the side surface of the intermediate layer. The upper surface of the ceramic plate and the lower surface of the intermediate layer are in contact. This is the ceramic substrate described in Appendix 10, wherein the upper surface of the ceramic plate and the lower surface of the Au layer are in contact. (Note 12) The aforementioned intermediate layer includes a Ni layer and a Pd layer. The Ni layer is arranged on the upper surface and side surface of the metal layer, and on the side surface of the Al layer. The Pd layer is arranged on the upper surface and the side surface of the Ni layer. The Au layer is a ceramic substrate as described in Appendix 10 or Appendix 11, which is disposed on the upper surface and the side surface of the Pd layer. (Note 13) The ceramic substrate is a ceramic substrate according to any one of the appendices 1 to 11, further having a second wiring portion arranged on the lower surface of the ceramic plate, which is the surface opposite to the upper surface of the ceramic plate. (Note 14) A ceramic substrate as described in any one of the items from Appendix 1 to Appendix 13, The light-emitting device has a light-emitting element disposed on the ceramic substrate. (Note 15) The light-emitting device includes a reflective member disposed on the upper surface of the ceramic substrate, The reflective member is the light-emitting device described in Appendix 14, which is in contact with the Al layer and the Au layer. (Note 16) A method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, This includes forming a first wiring section, Forming the first wiring section A first resist layer is placed on the upper surface of a ceramic plate containing aluminum nitride, The process involves irradiating the first resist layer with laser light so that Al is deposited on the upper surface of the ceramic plate, thereby forming an Al layer. Plating is performed on the upper surface of the Al layer and inside the through holes of the first resist layer with one or more metals selected from the group consisting of Zn, Ni, and Cu to form a metal layer with a minimum thickness of 18 μm or more. Removing the first resist layer. Forming an Au layer on the upper surface and the side surfaces of the metal layer. including In a cross-sectional view, the minimum thickness of the metal layer is such that when the horizontal length between one end and the other end of the metal layer is Lw, the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer is Pa, and the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer is Pb, it is the minimum thickness of the metal layer in the region between Pa and Pb. It is a method for manufacturing a ceramic substrate. (Appendix 17) A method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, including forming a first wiring portion, Forming the first wiring portion disposing a first resist layer on the upper surface of a ceramic plate containing aluminum nitride, irradiating laser light so as to penetrate the first resist layer and deposit Al on the upper surface of the ceramic plate to form an Al layer, Plating is performed on the upper surface of the Al layer and inside the through holes of the first resist layer with one or more metals selected from the group consisting of Zn, Ni, and Cu to form a metal layer with an average thickness of 20 μm or more. Removing the first resist layer. Forming an Au layer on the upper surface and the side surfaces of the metal layer. including The method for manufacturing a ceramic substrate is such that, in a cross-sectional view, Lw is the horizontal length between one end of the metal layer and the other end of the metal layer, Pa is the position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is the position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer, and Pb is the average thickness of the metal layer in the region between Pa and Pb. (Note 18) The method for manufacturing a ceramic substrate according to Appendix 16 or Appendix 17, wherein the first resist layer is a dry film. (Note 19) In forming the Al layer, the laser light is irradiated such that the shortest distance between the inner side surface of one through-hole in the first resist layer and the inner side surface of another through-hole adjacent to the first through-hole is 10 μm or more and 50 μm or less, according to any one of the appendices 16 to 18. (Note 20) In forming the Al layer, the method for manufacturing a ceramic substrate as described in any one of the appendices 16 to 19, wherein, in a cross-sectional view, Lz is the horizontal length between one end of the Al layer and the other end of the Al layer, Pc is the position Lz / 5 from one end of the Al layer toward the horizontal center of the Al layer, and Pd is the position Lz / 5 from the other end of the Al layer toward the horizontal center of the Al layer, and the laser light is irradiated such that the average thickness of the Al layer in the region between Pc and Pd is 0.2 μm or more and 5 μm or less. (Note 21) In forming the Al layer, the ceramic plate is thermally processed by irradiation with laser light to deposit the Al on the upper surface of the ceramic plate, as described in any one of the appendices 16 to 20. (Note 22) The method for manufacturing a ceramic substrate as described in Appendix 21, wherein the laser light is irradiated to form the Al layer in a manner that prevents oxidation of the deposited Al. (Note 23) The method for manufacturing a ceramic substrate as described in Appendix 22, wherein the laser light is irradiated to the same location only once when forming the Al layer. (Note 24) In forming the Al layer, the upper surface of the ceramic plate is irradiated with laser light so that the surface roughness Ra is 0.5 μm or more and 2.0 μm or less, as described in any one of the appendices 16 to 23. (Note 25) In forming the Al layer, the first resist layer is irradiated with laser light in a cross-sectional view such that the aperture is wide in the aperture direction, as described in any one of the appendices 16 to 24. (Note 26) The method further includes removing the first resist layer and forming one or more intermediate layers on the upper surface and side surfaces of the metal layer, The method for manufacturing a ceramic substrate according to any one of the appendices 16 to 25, wherein the Au layer is formed on the upper surface and the side surface of the intermediate layer. (Note 27) A method for manufacturing a ceramic substrate according to any one of the appendices 16 to 26, further comprising polishing or grinding the upper surface of the first resist layer and the upper surface of the metal layer after forming the metal layer. (Note 28) The process involves preparing the ceramic substrate manufactured by the method for manufacturing the ceramic substrate described in any one of the items from Appendix 16 to Appendix 27, This includes arranging a light-emitting element equipped with electrodes on the ceramic substrate, This is a method for manufacturing a light-emitting device, comprising electrically connecting the electrode and the first wiring section. [Explanation of Symbols]

[0235] 1. Ceramic plate 1A Surface of ceramic plate 1 1B Surface of ceramic plate 1 Top surface of 1U ceramic plate 1 Bottom surface of 1L ceramic plate 1 2A 1st wiring section 2A1 1st wiring section 2A2 1st wiring section 2B 2nd wiring section 3. Al layer 3a Edge of the upper surface of Al layer 3 4 metal layer 4b Edge of the lower surface of the metal layer 4 4A One end of metal layer 4 4B Other ends of metal layer 4 5 Au layer 5b Edge of the lower surface of the Au layer 6. Mesopotamian 6-1 First Meso-Place 6-1b Edge of the lower surface of the first intermediate layer 6-2 Second Meso-Marginal Layer 6-2b Edge of the lower surface of the second intermediate layer 10 Heat dissipation part 11 Beer 12 Pad section 12A pad section 12B Pad section 14 Recognition Mark 20 Light-emitting elements 30 Translucent material 40 Reflective material 41 Frame 42 Protective elements 50 First Resist Layer 50A Main part of the first resist layer 50B Protrusion S space 51 Through hole 51A through hole 51B Through hole 60 Joining members 61 Light guide member 62 holes 100 ceramic substrates 200 Light-emitting devices L Laser light Lm shortest distance Ln shortest distance

Claims

1. A ceramic plate containing aluminum nitride, A first wiring section is arranged on the upper surface of the ceramic plate, It has, The first wiring section is, An Al layer is placed on the upper surface of the ceramic plate, A metal layer comprising one or more metals selected from the group consisting of Zn, Ni, and Cu, disposed on the upper surface of the Al layer, Au layers are disposed on the upper surface and the side surface of the metal layer, It has, In the ceramic plate, the surface of the ceramic plate in the area where the Al layer is placed is rougher than the surface of the ceramic plate in the area where the Al layer is not placed. A ceramic substrate in which, in a cross-sectional view, Lw is the horizontal length between one end of the metal layer and the other end of the metal layer, Pa is defined as a position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is defined as a position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer, the minimum thickness of the metal layer in the region between Pa and Pb is 18 μm or more.

2. A ceramic plate containing aluminum nitride, A first wiring section is arranged on the upper surface of the ceramic plate, It has, The first wiring section is, An Al layer is placed on the upper surface of the ceramic plate, A metal layer comprising one or more metals selected from the group consisting of Zn, Ni, and Cu, disposed on the upper surface of the Al layer, Au layers are disposed on the upper surface and the side surface of the metal layer, It has, In the ceramic plate, the surface of the ceramic plate in the area where the Al layer is placed is rougher than the surface of the ceramic plate in the area where the Al layer is not placed. A ceramic substrate in which, in a cross-sectional view, Lw is the horizontal length between one end of the metal layer and the other end of the metal layer, Pa is defined as a position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is defined as a position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer, the average thickness of the metal layer in the region between Pa and Pb is 20 μm or more.

3. The ceramic substrate according to claim 1, wherein, in a cross-sectional view in the thickness direction of the ceramic substrate, the angle of the outer angle formed by the upper surface of the ceramic plate and the side surface of the metal layer is 85° or more and 95° or less.

4. The first wiring section has a plurality of parts, The ceramic substrate according to claim 1, wherein in a plurality of first wiring sections, the shortest distance between the side surface of the Au layer in one first wiring section and the side surface of the Au layer in another first wiring section adjacent to the one first wiring section is 10 μm or more and 100 μm or less.

5. The ceramic substrate according to claim 4, wherein, in a plan view, the area of ​​the metal layer is 100% or more and 105% or less of the area of ​​the Al layer.

6. In a cross-sectional view, when Lz is the horizontal length between one end of the Al layer and the other end of the Al layer, Pc is the position Lz / 5 from one end of the Al layer toward the horizontal center of the Al layer, and Pd is the position Lz / 5 from the other end of the Al layer toward the horizontal center of the Al layer, the average thickness of the Al layer in the region between Pc and Pd is 0.2 μm or more and 5 μm or less, the ceramic substrate according to claim 1.

7. The ceramic substrate according to claim 1, wherein, in the horizontal direction, the edge of the upper surface of the Al layer is inward from the edge of the lower surface of the Au layer.

8. The side surface of the Al layer is covered by the Au layer. The ceramic substrate according to claim 1, wherein the upper surface of the ceramic plate and the lower surface of the Au layer are in contact.

9. The ceramic substrate according to claim 1, wherein the surface roughness Ra of the ceramic plate in the area where the Al layer is arranged is 0.5 μm or more and 2.0 μm or less.

10. The ceramic substrate according to claim 1, wherein the first wiring portion further comprises one or more intermediate layers disposed on the upper surface and the side surface of the metal layer.

11. The side surface of the Al layer is covered by the intermediate layer. The Au layer is arranged on the upper surface and the side surface of the intermediate layer. The upper surface of the ceramic plate and the lower surface of the intermediate layer are in contact. The ceramic substrate according to claim 10, wherein the upper surface of the ceramic plate and the lower surface of the Au layer are in contact.

12. The aforementioned intermediate layer includes a Ni layer and a Pd layer. The Ni layer is arranged on the upper surface and side surface of the metal layer, and on the side surface of the Al layer. The Pd layer is arranged on the upper surface and the side surface of the Ni layer. The ceramic substrate according to claim 10, wherein the Au layer is disposed on the upper surface and the side surface of the Pd layer.

13. The ceramic substrate according to claim 1, further comprising a second wiring portion disposed on the lower surface of the ceramic plate, which is the surface opposite to the upper surface of the ceramic plate.

14. A ceramic substrate according to any one of claims 1 to 13, A light-emitting device having a light-emitting element disposed on the ceramic substrate.

15. The light-emitting device includes a reflective member disposed on the upper surface of the ceramic substrate, The light-emitting device according to claim 14, wherein the reflective member is in contact with the Al layer and the Au layer.

16. A method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, This includes forming a first wiring section, Forming the first wiring section A first resist layer is placed on the upper surface of a ceramic plate containing aluminum nitride, The process involves irradiating the first resist layer with laser light so that Al is deposited on the upper surface of the ceramic plate, thereby forming an Al layer. Plating is performed on the inside of the through-holes in the first resist layer and on the upper surface of the Al layer with one or more metals selected from the group consisting of Zn, Ni, and Cu, thereby forming a metal layer with a minimum thickness of 18 μm or more. Removing the first resist layer, Au layer is formed on the upper surface and side surface of the metal layer, Includes, A method for manufacturing a ceramic substrate, wherein the minimum thickness of the metal layer is the minimum thickness of the metal layer in the region between Pa and Pb, where Lw is the horizontal length between one end of the metal layer and the other end of the metal layer in a cross-sectional view, Pa is a position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is a position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer.

17. A method for manufacturing a ceramic substrate having a first wiring portion on the upper surface of a ceramic plate, This includes forming a first wiring section, Forming the first wiring section A first resist layer is placed on the upper surface of a ceramic plate containing aluminum nitride, The process involves irradiating the first resist layer with laser light so that Al is deposited on the upper surface of the ceramic plate, thereby forming an Al layer. Plating is performed on the inside of the through-holes in the first resist layer and on the upper surface of the Al layer with one or more metals selected from the group consisting of Zn, Ni, and Cu, thereby forming a metal layer with an average thickness of 20 μm or more. Removing the first resist layer, Au layer is formed on the upper surface and side surface of the metal layer, Includes, A method for manufacturing a ceramic substrate, wherein the average thickness of the metal layer is the average thickness of the metal layer in the region between Pa and Pb, where Lw is the horizontal length between one end of the metal layer and the other end of the metal layer in a cross-sectional view, Pa is a position Lw / 5 from one end of the metal layer toward the horizontal center of the metal layer, and Pb is a position Lw / 5 from the other end of the metal layer toward the horizontal center of the metal layer.

18. The method for manufacturing a ceramic substrate according to claim 16, wherein the first resist layer is a dry film.

19. The method for manufacturing a ceramic substrate according to claim 16, wherein, in forming the Al layer, the laser light is irradiated such that the shortest distance between the inner side surface of one through-hole in the first resist layer and the inner side surface of another through-hole adjacent to the first through-hole is 10 μm or more and 50 μm or less.

20. A method for manufacturing a ceramic substrate according to claim 16, wherein, in forming the Al layer, Lz is the horizontal length between one end of the Al layer and the other end of the Al layer in a cross-sectional view, Pc is the position Lz / 5 from one end of the Al layer toward the horizontal center of the Al layer, and Pd is the position Lz / 5 from the other end of the Al layer toward the horizontal center of the Al layer, and the laser light is irradiated such that the average thickness of the Al layer in the region between Pc and Pd is 0.2 μm or more and 5 μm or less.

21. The method for manufacturing a ceramic substrate according to claim 16, wherein, in forming the Al layer, the ceramic plate is thermally processed by irradiation with laser light to deposit the Al on the upper surface of the ceramic plate.

22. The method for manufacturing a ceramic substrate according to claim 21, wherein, in forming the Al layer, the laser light is irradiated so that the deposited Al does not oxidize.

23. The method for manufacturing a ceramic substrate according to claim 22, wherein, in forming the Al layer, the laser light is irradiated to the same location only once.

24. The method for manufacturing a ceramic substrate according to claim 16, wherein, in forming the Al layer, the upper surface of the ceramic plate is irradiated with laser light so that the surface roughness Ra is 0.5 μm or more and 2.0 μm or less.

25. The method for manufacturing a ceramic substrate according to claim 16, wherein, in forming the Al layer, laser light is irradiated onto the first resist layer in a cross-sectional view such that the aperture is wide in the aperture direction.

26. The method further includes removing the first resist layer and then forming one or more intermediate layers on the upper surface and the side surfaces of the metal layer, The method for manufacturing a ceramic substrate according to claim 16, wherein the Au layer is formed on the upper surface and the side surface of the intermediate layer.

27. A method for manufacturing a ceramic substrate according to claim 16, further comprising polishing or grinding the upper surface of the first resist layer and the upper surface of the metal layer after forming the metal layer.

28. The process involves preparing the ceramic substrate manufactured by the method for manufacturing the ceramic substrate described in any one of claims 16 to 27, This includes arranging a light-emitting element equipped with electrodes on the ceramic substrate, A method for manufacturing a light-emitting device, comprising electrically connecting the electrode and the first wiring section.

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