Wiring board, compound board, and manufacturing method for these

Abstract

To provide a wiring board with high thermal conductivity at connection to another component.SOLUTION: A wiring board according to the present disclosure includes: a ceramic substrate having an upper surface, a lower surface on the opposite side of the upper surface, and a side surface between the upper surface and the lower surface, in which the lower surface includes a first lower surface on the outermost side and a second lower surface inside the first lower surface and the side surface includes a first side surface on the outermost side and a second side surface on the innermost side of the lower surface side; and a first wire having a thickness of 80% or more of the height from the second lower surface to the first lower surface and disposed in contact with the second lower surface and the second side surface. A side surface of the first wire is exposed from the first side surface of the ceramic substrate. A main surface corresponding to 50% or more of the surface area of the lower surface of the first wire is substantially parallel to the second lower surface and is disposed inside the first lower surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a wiring board, a composite board, and a method for manufacturing the same. [Background technology]

[0002] A known wiring board is one that has a conductive pattern formed on the inside and surface of a ceramic substrate using a conductive material such as a metal. Such a wiring board is connected to other components by soldering or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-106325 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of an embodiment of the present disclosure is to provide a wiring board that has high thermal conductivity with another component when connected to the other component, and a manufacturing method thereof. [Means for solving the problem]

[0005] A first aspect of the present disclosure is a wiring board having a ceramic substrate having an upper surface, a lower surface opposite the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located inside the first lower surface, the side surface having an outermost first side surface and an innermost second side surface on the lower surface side, and a first wiring having a thickness of 80% or more of a height from the second lower surface to the first lower surface and arranged in contact with the second lower surface and the second side surface, the side surface of the first wiring being exposed from the first side surface of the ceramic substrate, and a main surface accounting for 50% or more of the surface area of ​​the lower surface of the first wiring being approximately parallel to the second lower surface and being arranged inside the first lower surface.

[0006] A second aspect of the present disclosure is a composite substrate including the wiring substrate, a first component, and a connection member that electrically connects the first wiring of the wiring substrate and the first component.

[0007] A third aspect of the present disclosure includes preparing a ceramic substrate having an upper surface, a lower surface opposite the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located more inward than the first lower surface, the side surface having an outermost first side surface and an innermost second side surface on the lower surface side, disposing a first conductive paste on the second lower surface to form a first conductive paste layer, firing the first conductive paste layer to form a first wiring intermediate body, and a first wiring intermediate body is polished or ground to form a first wiring having a main surface that accounts for 50% or more of the surface area of ​​the lower surface of the first wiring, the main surface being approximately parallel to the second lower surface and positioned more inward than the first lower surface, wherein in forming the first wiring, the first wiring has a thickness that is 80% or more of the height from the second lower surface to the first lower surface, is positioned in contact with the second lower surface and the second side surface, and the side surface of the first wiring is exposed from the first side surface of the ceramic substrate. Effect of the Invention

[0008] According to one aspect of the present disclosure, it is possible to provide a wiring board that has high thermal conductivity with another component when connected to the other component, and a manufacturing method thereof. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic bottom view showing the wiring board according to the first embodiment. [Diagram 2] 1 is a schematic plan view showing a wiring board according to a first embodiment. [Diagram 3] 2 is a schematic cross-sectional view showing a cross section taken along line III-III in FIG. [Figure 4] FIG. 4 is a partially enlarged view of FIG. [Figure 5A]1 is a schematic cross-sectional view showing a prepared ceramic substrate in a method for manufacturing a wiring board according to a first embodiment. [Figure 5B] 3 is a schematic cross-sectional view showing a state in which a first conductive paste layer and a second conductive paste layer are arranged in the method for manufacturing a wiring board according to the first embodiment. FIG. [Figure 5C] 4 is a schematic cross-sectional view showing a state in which a first wiring intermediate body and a second wiring intermediate body have been formed in the method for manufacturing a wiring board according to the first embodiment. FIG. [Figure 5D] 4 is a schematic cross-sectional view showing a state in which a first wiring and a second wiring have been formed in the method for manufacturing a wiring board according to the first embodiment. FIG. [Figure 5E] 3 is a schematic cross-sectional view showing a state in which a first metal layer and a second metal layer are arranged in the method for manufacturing a wiring board according to the first embodiment. FIG. [Figure 6] FIG. 11 is a schematic bottom view showing a wiring board according to a second embodiment. [Figure 7] 7 is a schematic cross-sectional view showing a cross section taken along line VII-VII in FIG. 6. [Figure 8] FIG. 13 is a schematic bottom view showing a wiring board according to a third embodiment. [Figure 9] 9 is a schematic cross-sectional view showing a cross section taken along line IX-IX in FIG. 8. [Figure 10] FIG. 13 is a schematic bottom view showing a wiring board according to a fourth embodiment. [Figure 11A] 13 is a schematic bottom view showing a prepared ceramic substrate in a method for manufacturing a wiring board according to a fourth embodiment. FIG. [Figure 11B] 11B is a schematic cross-sectional view showing a cross section taken along line XIB-XIB in FIG. 11A. [Figure 11C] 11B is a schematic cross-sectional view showing a cross section taken along line XIC-XIC in FIG. 11A. [Figure 12] 1 is a schematic cross-sectional view showing a wiring board according to a first modified example. [Figure 13] FIG. 11 is a schematic cross-sectional view showing a composite substrate according to a fifth embodiment. [Figure 14] FIG. 13 is a schematic cross-sectional view showing a composite substrate according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings. However, the embodiment described below is for embodying the technical idea according to the present disclosure, and the invention is not limited to the following unless otherwise specified. The contents described in one embodiment are applicable to other embodiments and modified examples. In addition, the drawings are schematic diagrams of the embodiments, and in order to clarify the description, the scale, interval, positional relationship, etc. of each member may be exaggerated, or some of the members may be omitted, or an end view showing only the cut surface may be used as a cross-sectional view. The directions shown in each figure indicate the relative positions between the components, and are not intended to indicate absolute positions. In addition, the same names and symbols indicate, in principle, the same or homogeneous members, and detailed descriptions are omitted as appropriate.

[0011] (First embodiment) A wiring board 1a according to a first embodiment and a manufacturing method thereof will be described with reference to FIGS. 1 to 4 and 5A to 5E. FIG. 1 is a schematic bottom view showing the wiring board 1a. FIG. 2 is a schematic plan view showing the wiring board 1a. FIG. 3 is a schematic cross-sectional view showing a cross section along line III-III in FIG. 1. FIG. 4 is an enlarged view of a portion in FIG. 3 where the first wiring 3 and the second wiring 5 are located. FIGS. 5A to 5E are schematic cross-sectional views for explaining a manufacturing method of the wiring board 1a shown in FIGS. 1 to 4. The dotted lines in FIGS. 5A to 5E indicate the planned cutting points of the ceramic substrate.

[0012] The wiring board 1a of the first embodiment according to the present disclosure has an upper surface 21, a lower surface 22 opposite the upper surface 21, and a side surface 23 between the upper surface 21 and the lower surface 22, the lower surface 22 having an outermost first lower surface 22a and a second lower surface 22b located inside the first lower surface 22a, the side surface 23 having an outermost first side surface 23a and an innermost second side surface 23b on the lower surface 22 side. The wiring board 1a of the first embodiment according to the present disclosure has a ceramic substrate 2 having a first wiring 3 having a thickness of 80% or more of the height from the second lower surface 22b to the first lower surface 22a and arranged in contact with the second lower surface 22b and the second side surface 23b, the side surface 31 of the first wiring 3 being exposed from the first side surface 23a of the ceramic substrate 2, and a main surface of 50% or more of the surface area of ​​the lower surface 32 of the first wiring 3 being approximately parallel to the second lower surface 22b and arranged inside the first lower surface 22a. The wiring board 1a is rectangular in top view, and the side of the wiring board 1a includes a front surface 11, a right side surface 12 and a left side surface 13 adjacent to the front surface 11, and a back surface 14 opposite the front surface 11 and adjacent to the right side surface 12 and the left side surface 13. The first wiring 3 is present on the front surface 11, the right side surface 12, the left side surface 13, and the back surface 14. The top surface 21 includes a first top surface 21a located on the outermost side, and a second top surface 21b located inside the first top surface 21a. The ceramic substrate 2 has a recess 25 defined by the second top surface 21b and a fifth side surface 24 located between the first top surface 21a and the second top surface 21b. The wiring board 1a has a second wiring 5 in the recess 25. The second wiring 5 has a thickness of 80% or more of the height from the second upper surface 21b to the first upper surface 21a of the ceramic substrate 2, and is disposed in contact with the second upper surface 21b. A main surface of 50% or more of the surface area of ​​the upper surface 52 of the second wiring 5 is substantially parallel to the second upper surface 21b, and is disposed inside the first upper surface 21a. The wiring substrate 1a has a first metal layer 4 disposed on the lower surface 32 of the first wiring 3. The wiring substrate 1a has a second metal layer 6 disposed on the upper surface 52 of the second wiring 5. As shown in FIG. 4, in a cross-sectional view in the thickness direction of the ceramic substrate 2, a first corner 27 defined by the first lower surface 22a and the second side surface 23b is rounded, and the first metal layer 4 covers the first corner 27. A second corner portion 28 defined by the first upper surface 21a and the fifth side surface 24 is rounded, and the second metal layer 6 covers the second corner portion 28.

[0013] (Method of Manufacturing Wiring Board) A method for manufacturing a wiring board 1a according to a first embodiment of the present disclosure includes: (a) preparing a ceramic substrate 2 having an upper surface 21, a lower surface 22 opposite to the upper surface 21, and a side surface 23 between the upper surface 21 and the lower surface 22, the lower surface 22 having a first lower surface 22a which is the outermost surface and a second lower surface 22b which is the inner surface of the first lower surface 22a, the side surface 23 having a first side surface 23a which is the outermost surface and a second side surface 23b which is the innermost surface on the lower surface 22 side; (b) arranging a first conductive paste on the second lower surface 22b to form a first conductive paste layer 41; and (c) forming a first conductive paste layer 41 on the second lower surface 22b. (d) polishing or grinding the first wiring intermediate 43 to form a first wiring 3 having a main surface that accounts for 50% or more of the surface area of ​​the lower surface 32 of the first wiring 3, which is approximately parallel to the second lower surface 22b and is positioned more inward than the first lower surface 22a, wherein (b) in forming the first wiring 3, the first wiring 3 has a thickness that is 80% or more of the height from the second lower surface 22b to the first lower surface 22a, is positioned in contact with the second lower surface 22b and the second side surface 23b, and the side surface 31 of the first wiring 3 is exposed from the first side surface 23a of the ceramic substrate 2.

[0014] The method for manufacturing the wiring board 1a of the first embodiment according to the present disclosure preferably further includes, in preparing the ceramic substrate 2, preparing the ceramic substrate 2 having, on the upper surface 21, a first upper surface 21a and a second upper surface 21b located inside the first upper surface 21a. Furthermore, after preparing the ceramic substrate 2, it is preferable to further include disposing a second conductive paste on the second upper surface 21b to form a second conductive paste layer 42, and in forming the first wiring intermediate body 43, firing the second conductive paste layer 42 to form a second wiring intermediate body 44. Note that, in the method for manufacturing the wiring board of the present disclosure, these steps may not be present. That is, the wiring substrate of the present disclosure may not have the second upper surface 21b and the second wiring 5. In other words, the upper surface 21 of the ceramic substrate 2 may be only the first upper surface 21a.

[0015] The method for manufacturing the wiring board 1a of the first embodiment according to the present disclosure preferably further includes (e) forming a first metal layer 4 on the lower surface 32 of the first wiring 3. The method for manufacturing the wiring board 1a of the first embodiment according to the present disclosure preferably further includes forming a second metal layer 6 on the upper surface 52 of the second wiring 5.

[0016] Each step will be described in detail below.

[0017] (a) Preparing a ceramic substrate A ceramic substrate 2 is prepared (FIG. 5A).

[0018] The ceramic substrate 2 is an insulating member that will later become a base on which the first wiring 3 and the second wiring 5 are arranged. The ceramic substrate 2 has an upper surface 21, a lower surface 22 opposite to the upper surface 21, and a side surface 23 between the upper surface 21 and the lower surface 22. The lower surface 22 has a first lower surface 22a that is the outermost surface, and a second lower surface 22b that is located inside the first lower surface 22a. The side surface 23 has a first side surface 23a that is the outermost surface, and a second side surface 23b that is the innermost surface on the lower surface 22 side. The second lower surface 22b and the second side surface 23b define a first arrangement portion 26. The first wiring 3 is arranged in the first arrangement portion 26. The upper surface 21 has a first upper surface 21a that is the outermost surface, and a second upper surface 21b that is located inside the first upper surface 21a. The ceramic substrate 2 has a second upper surface 21b and a recess 25 defined by a fifth side surface 24 between the first upper surface 21a and the second upper surface 21b. Although one ceramic substrate 2 is illustrated, an aggregate substrate in which a plurality of ceramic substrates 2 are aligned in row and column directions can be used.

[0019] From the viewpoint of heat dissipation, ceramics having high thermal conductivity are preferable as the material for the ceramic substrate 2. For example, nitride-based ceramics such as silicon nitride, aluminum nitride, and boron nitride are preferable as the material for the ceramic substrate 2, but oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide may also be used.

[0020] The thickness of the ceramic substrate 2 is preferably, for example, 0.08 mm or more and 2 mm or less. The thickness of the ceramic substrate 2 means the distance between the first upper surface 21a and the first lower surface 22a.

[0021] The first arrangement portions 26 are rectangular in plan view and have a long side direction and a short side direction. The two first arrangement portions 26 are arranged side by side with their long sides facing each other.

[0022] The recess 25 has a rectangular shape in a plan view and has a long side direction and a short side direction. The two recesses 25 are arranged side by side with their long sides facing each other.

[0023] As shown in FIG. 4, in a cross-sectional view in the thickness direction of the ceramic substrate 2, a first corner 27 defined by the first lower surface 22a and the second side surface 23b is rounded. In addition, in a cross-sectional view in the thickness direction of the ceramic substrate 2, a second corner 28 defined by the first upper surface 21a and the fifth side surface 24 is rounded. Since the first corner 27 and the second corner 28 are rounded, the contact areas between the ceramic substrate 2 and the first metal layer 4 and the second metal layer 6 are increased, respectively, and thus the adhesiveness is improved. In addition, since the distance from the first lower surface 22a to the first wiring 3 and the distance from the first upper surface 21a to the second wiring 5 are increased, the length of the portion where the ceramic substrate 2 contacts the first metal layer 4 and the second metal layer 6 in the cross-sectional view is increased. That is, the intrusion path of substances from the external environment, such as oxygen, sulfur, and moisture, is increased. Therefore, substances entering from the external environment are less likely to reach the first wiring 3 and the second wiring 5, and deterioration of the first wiring 3 and the second wiring 5 can be suppressed. Typically, sulfurization of the first wiring 3 and the second wiring 5 is suppressed.

[0024] It is preferable that the inner surfaces defining the first arrangement portion 26 and the recess 25, i.e., the second lower surface 22b, the second side surface 23b, the second upper surface 21b, and the fifth side surface 24, are roughened. By roughening the surfaces, peeling of the first wiring 3 and the second wiring 5 disposed in the first arrangement portion 26 and the recess 25 can be reduced. The arithmetic mean roughness Ra of the inner surfaces defining the first arrangement portion 26 and the recess 25 can be, for example, 200 nm or more and 2 μm or less, and preferably 300 nm or more and 800 nm or less. The arithmetic mean roughness Ra may be measured in accordance with JIS B 0601 using a stylus-type surface roughness meter (for example, SE3500 manufactured by Kosaka Laboratory Co., Ltd.) equipped with a diamond stylus with a tip curvature radius r of 2 μm.

[0025] The ceramic substrate 2 is a sintered substrate. If a conductive paste is applied using a green sheet before sintering, the green sheet may warp or shrink significantly, making it difficult to precisely arrange the first wiring 3 and the second wiring 5. In contrast, in this embodiment, a sintered ceramic substrate is used and the conductive paste is applied, so warping and shrinkage are significantly reduced and the first wiring 3 and the second wiring 5 can be precisely arranged.

[0026] The ceramic substrate 2 may be formed by firing ceramics, or a fired substrate such as a commercially available product may be used. The first arrangement portion 26 and the recess 25 in the ceramic substrate 2 may be present in advance, or may be formed after purchasing a fired substrate such as a commercially available product. Also, a substrate on which the first arrangement portion 26 and the recess 25 are formed may be purchased as the ceramic substrate 2.

[0027] The first arrangement portion 26 and the recess 25 can be formed by, for example, etching, blasting, or laser processing, but laser processing is preferable because it can form the recess 25 with high accuracy. Note that only one of the etching, blasting, and laser processing may be performed, or two or more of them may be combined. During such processing, the first corner portion 27 and the second corner portion 28 may be rounded.

[0028] The etching can be performed by wet etching or dry etching, and wet etching is preferable. The wet etching can form the curved first arrangement portion 26 by etching using an acidic or alkaline agent such as HF, NHF, KOH, NaOH, or CsOH.

[0029] In blasting, abrasive grains are collided with the upper surface 21 or the lower surface 22 in a perpendicular direction, thereby polishing or grinding the ceramic substrate 2 to form a desired shape.

[0030] Prior to the etching or blasting process, a resist having a predetermined pattern may be disposed. For example, the resist is formed as follows.

[0031] A dry film is attached to the upper surface 21 and the lower surface 22 of the ceramic substrate 2. The dry film is a sheet-like photoresist. For example, a dry film that hardens in an exposed area is used.

[0032] Next, the dry film is exposed to light and developed. Before exposure, a mask is attached over the dry film. The mask has a light-shielding pattern in the area where the first arrangement portion 26 and the recess 25 are to be formed. Next, light is irradiated to perform exposure. The light is, for example, ultraviolet light. The light is transmitted through the areas other than the light-shielding pattern, and the dry film in those positions is hardened. In the subsequent development, the mask is removed, and the unhardened parts of the dry film are dissolved and removed with an alkaline aqueous solution or the like. The hardened parts remain without being dissolved and removed, forming a resist.

[0033] The resist is removed after etching or blasting.

[0034] For example, preparing the ceramic substrate may include arranging a photoresist on the upper surface 21 and / or the lower surface 22 of the ceramic substrate 2, exposing and developing the photoresist through a mask, etching or blasting the ceramic substrate 2 through the photoresist formed in a predetermined pattern by the exposure and development, forming the first arrangement portion 26 and / or the recessed portion 25 by etching or blasting, and removing the photoresist from the ceramic substrate 2. Alternatively, the ceramic substrate may be prepared, and the first arrangement portion 26 and / or the recessed portion 25 may be formed by directly irradiating the substrate with a laser without using a photoresist.

[0035] (b) forming a conductive paste layer; A first conductive paste is disposed on the second lower surface 22b to form a first conductive paste layer 41. In the first embodiment, a second conductive paste is disposed on the second upper surface 21b to form a second conductive paste layer 42 (FIG. 5B). The first conductive paste and the second conductive paste may be collectively referred to as the conductive paste. The first conductive paste layer and the second conductive paste layer may be collectively referred to as the conductive paste layer.

[0036] A first conductive paste is placed in the first placement portion 26 of the ceramic substrate 2 to form a first conductive paste layer 41. The first conductive paste layer 41 becomes the first wiring 3 by firing. The first conductive paste is a member having fluidity, and can be applied and placed so as to adhere to the second lower surface 22b and the second side surface 23b. Similarly, a second conductive paste is placed in the recess 25 of the ceramic substrate 2 to form a second conductive paste layer 42. The second conductive paste layer 42 becomes the second wiring 5 by firing. The conductive paste can be applied and placed so as to adhere to the second upper surface 21b and the fifth side surface 24. Here, the first placement portion 26 and the recess 25 are filled with the conductive paste up to a position higher than the height of the first lower surface 22a and the first upper surface 21a. The present disclosure is not limited to such an embodiment, and the conductive paste may be placed, for example, up to the same position as the first lower surface 22a and the first upper surface 21a, or up to a position lower than the first lower surface 22a and the first upper surface 21a. In this case, the second wiring intermediate body may be used as the second wiring 5 as it is.

[0037] The conductive paste contains a first metal powder. The first metal powder may contain at least one selected from Ag, Cu, Al, Zn, Sn, Ni, and an Ag-Cu alloy. Among these, an Ag-Cu alloy that can be fired at a relatively low temperature of 780°C to 950°C is preferred. The Ag-Cu alloy may also contain Cu, Ag, etc. together with the Ag-Cu alloy having high electrical conductivity. This allows firing at a temperature lower than the melting points of Ag and Cu, and allows wiring to be formed that has a thermal conductivity close to that of 100% Ag or Cu. When the conductive paste containing the first metal powder is placed in the first arrangement portion 26 or the recess 25, the size of the first metal powder may be smaller than the depth of the first arrangement portion 26 or the recess 25. For example, the median diameter of the first metal powder is preferably 0.5 μm to 50 μm, more preferably 0.8 μm to 20 μm, and particularly preferably 1 μm to 3 μm. By setting the median diameter of the first metal powder to 1 μm or more, aggregation can be suppressed and thermal conductivity can be increased. On the other hand, by setting the median diameter of the first metal powder to 3 μm or less, packing properties can be increased. In addition, the shape of the first metal powder is preferably spherical or elliptical from the viewpoint of fluidity, but it may also be flat or acicular. This is because the flat or acicular shape can increase contact between particles, increase thermal conductivity, and reduce electrical resistance.

[0038] The conductive paste may contain at least an active metal powder. The active metal powder may be at least one selected from TiH2, CeH2, ZrH2, and MgH2. Among these, TiH2 is preferable. By containing TiH2, it reacts with nitrogen contained in the ceramic substrate 2 to form a metal compound layer that becomes a reaction layer such as TiN at the interface with the ceramic substrate 2. This improves the adhesion between the ceramic substrate 2 and the first wiring 3 and second wiring 5, which are formed by hardening the conductive paste.

[0039] The conductive paste may further contain a first organic solvent. Examples of the first organic solvent include those used in general conductive pastes. For example, glycol-based solvents, carbitol-based solvents, and terpineol-based solvents are included.

[0040] The conductive paste may further include a first organic resin binder. The viscosity of the conductive paste can be adjusted by the type and amount of the first organic resin binder. The first organic resin binder may be, for example, a solvent generally used in conductive pastes, or a resin material such as acrylic, epoxy, urethane, ethyl cellulose, silicone, phenol, polyimide, polyurethane, melamine, or urea. The organic binder is decomposed and evaporated by firing, which will be described later.

[0041] The conductive paste may contain a plurality of inorganic fillers other than metal. By containing the inorganic filler, the volumetric shrinkage of the conductive paste during sintering can be reduced. As the inorganic filler, for example, AlN, Si3N4, etc. can be used.

[0042] The first conductive paste and the second conductive paste may be the same or different, but preferably the first conductive paste and the second conductive paste are the same.

[0043] (c) Firing the conductive paste layer to form a wiring intermediate body. The first conductive paste layer 41 is fired to form a first wiring intermediate body 43. In the first embodiment, the second conductive paste layer 42 is fired at the same time to form a second wiring intermediate body 44 (FIG. 5C).

[0044] The firing temperature when firing the conductive paste layer can be 700° C. or more and 1200° C. or less, preferably 750° C. or more and 1100° C. or less, more preferably 780° C. or more and 950° C. or less, and particularly preferably 780° C. or more and 850° C. or less. -3 It is preferable to use a vacuum atmosphere of less than 1 Pa or an Ar atmosphere of 99.9% or more.

[0045] The wiring intermediate body may be formed by a method other than forming a conductive paste layer and firing it. As another method, a plating seed layer may be formed on both sides of the ceramic substrate including the first arrangement portion 26 and / or the recessed portion 25 by sputtering or the like, and then the wiring intermediate body may be formed by electrolytic plating, for example, electrolytic copper plating.

[0046] (d) Polishing or grinding the intermediate wiring body to form wiring. The first wiring intermediate body 43 is polished or ground to form a first wiring 3 in which a main surface of 50% or more of the surface area of ​​the lower surface 32 of the first wiring 3 is substantially parallel to the second lower surface 22b and is disposed inside the first lower surface 22a. The formed first wiring 3 and the first lower surface 22a are preferably separated. In the first embodiment, the second wiring intermediate body 44 is polished or ground to form a second wiring 5 in which a main surface of 50% or more of the surface area of ​​the upper surface 52 of the second wiring 5 is substantially parallel to the second upper surface 21b and is disposed inside the first upper surface 21a (FIG. 5D). The formed second wiring 5 and the first upper surface 21a are preferably separated.

[0047] The first wiring intermediate body 43 is polished and ground so that the main surface of 50% or more, preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more of the surface area of ​​the lower surface 32 of the first wiring 3 is substantially parallel to the second lower surface 22b. The first wiring 3 may be located at a higher position than the main surface at a portion contacting the second side surface 23b. That is, the first wiring 3 may be located closer to the first lower surface 22a than the main surface at a portion contacting the second side surface 23b. For example, the first wiring 3 may be at the same height as the first lower surface 22a at the boundary portion with the first lower surface 22a. Note that substantially parallel may include not only the case where the first wiring 3 is strictly parallel, but also the case where the deviation from parallel is 5° or less (typically 3° or less). The first wiring intermediate body 43 is polished and ground so that the first wiring 3 is disposed inside the first lower surface 22a. Here, "the first wiring 3 is disposed on the inside of the first lower surface 22a" means that the main surface of the first wiring 3 is located on the inside of the first lower surface 22a. For example, the boundary portion of the first wiring 3 with the first lower surface 22a may be at the same height as the first lower surface 22a, and the other portion may be located on the inside of the first lower surface 22a. Preferably, the polishing and grinding are performed so that the first wiring 3 and the first lower surface 22a are separated from each other. As described above, substances that enter from the external environment, such as oxygen, sulfur, and moisture, are less likely to reach the first wiring 3, and deterioration of the first wiring 3 can be suppressed.

[0048] The polishing and grinding of the second wiring intermediate body 44 is performed so that the main surface of 50% or more, preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more of the surface area of ​​the upper surface 52 of the second wiring 5 is approximately parallel to the second upper surface 21b. The second wiring 5 may be located at a higher position than the main surface at a portion contacting the fifth side surface 24. That is, the second wiring 5 may be located closer to the first upper surface 21a than the main surface at a portion contacting the fifth side surface 24. For example, the second wiring 5 may be at the same height as the first upper surface 21a at the boundary portion with the first upper surface 21a. The polishing and grinding of the second wiring intermediate body 44 is performed so that the second wiring 5 is disposed inside the first upper surface 21a. Here, "the second wiring 5 is disposed inside the first upper surface 21a" means that the main surface of the second wiring 5 is located inside the first upper surface 21a. For example, the boundary portion between the second wiring 5 and the first upper surface 21a may be at the same height as the first upper surface 21a, and the other portion may be located inside the first upper surface 21a. Preferably, the polishing and grinding are performed so that the second wiring 5 and the first upper surface 21a are separated from each other.

[0049] The polishing or grinding can be carried out, for example, by polishing with abrasive grains or by grinding with a grindstone embedded with diamonds.

[0050] In forming the first wiring, it is preferable to polish or grind the first wiring intermediate body so that the main surface of the lower surface 32 of the first wiring 3 is located at least 0.4 μm or more, for example 0.6 μm or more, 0.8 μm or more, or 1.0 μm or more, inside the first lower surface 22 a. The main surface of the lower surface 32 of the first wiring 3 is preferably located within 5.0 μm, for example 3.0 μm or less, 2.0 μm or less, or 1.5 μm or less, from the first lower surface 22 a.

[0051] In forming the second wiring, it is preferable to polish or grind the second wiring intermediate body so that the main surface of the upper surface 52 of the second wiring 5 is located at least 0.4 μm or more, for example 0.6 μm or more, 0.8 μm or more, or 1.0 μm or more inside the first upper surface 21 a. The main surface of the upper surface 52 of the second wiring 5 is preferably located within 5.0 μm, for example 3.0 μm or less, 2.0 μm or less, or 1.5 μm or less, from the first upper surface 21 a.

[0052] In the wiring board of the present disclosure, the subsequent step (e) may not be performed, and the first wiring intermediate body and the second wiring intermediate body may serve as the first wiring and the second wiring, respectively.

[0053] (e) forming a metal layer on the wiring; After the first wiring 3 is formed, the first metal layer 4 is further formed on the lower surface 32 of the first wiring 3. In forming the first metal layer 4, the first metal layer 4 is formed so that the surface 4a of the first metal layer 4 and the first lower surface 22a are flush with each other or the surface 4a of the first metal layer 4 is more convex than the first lower surface 22a. The height of the convexity from the first lower surface 22a is preferably 3 μm or less. After forming the second wiring 5, the second metal layer 6 is further formed on the upper surface 52 of the second wiring 5. In forming the second metal layer 6, the second metal layer 6 is formed so that the surface 6a of the second metal layer 6 and the first upper surface 21a are flush with each other or the surface 6a of the second metal layer 6 is more convex than the first upper surface 21a (FIG. 5E). The height of the convexity from the first upper surface 21a is preferably 3 μm or less. The first metal layer 4 and the second metal layer 6 may be collectively referred to as a metal layer. Here, the surface 4a of the first metal layer 4 being flush with the first lower surface 22a means that the main surface of the surface 4a of the first metal layer 4 is flush with the first lower surface 22a. For example, even if the edge of the first metal layer 4 is located outside the first lower surface 22a, it is sufficient that the main surface of the surface 4a of the first metal layer 4 is flush with the first lower surface 22a. The same applies to the surface 6a of the second metal layer 6 and the first upper surface 21a.

[0054] The metal layer may contain at least one selected from, for example, gold, platinum, palladium, rhodium, nickel, tungsten, molybdenum, chromium, and titanium. The metal layer may be a single layer or may be a multilayer. The metal layer may be formed by, for example, plating (electrolytic plating or electroless plating), vapor deposition, sputtering, or the like. At least one of the first metal layer 4 and the second metal layer 6 is preferably formed by plating. It is particularly preferable that both the first metal layer 4 and the second metal layer 6 are formed by plating. The metal layer may be formed through a mask. The first metal layer 4 and the second metal layer 6 may have the same structure or different structures. For example, the first metal layer 4 and the second metal layer 6 may contain the same metal or different metals. In addition, the first metal layer 4 and the second metal layer 6 may have the same layer structure or different layer structures.

[0055] In forming the first metal layer 4 and the second metal layer 6, it is preferable to press the edge of at least one of the first metal layer 4 and the second metal layer 6. That is, it is preferable to press at least one of the first metal layer 4 and the second metal layer 6 at the boundary portion with the ceramic substrate 2 toward the inside in the thickness direction of the ceramic substrate 2. At least one edge of the first metal layer 4 and the second metal layer 6 is formed in a state floating from the ceramic substrate 2, and a gap may be generated between at least one of the first metal layer 4 and the second metal layer 6 and the ceramic substrate 2. By pressing, at least one of the first metal layer 4 and the second metal layer 6 is more closely attached to the ceramic substrate 2, and the gap between at least one of the first metal layer 4 and the second metal layer 6 and the ceramic substrate 2 is reduced. This makes it possible to suppress the deterioration of the first wiring 3 and the second wiring 5 due to the influence of the external environment. Typically, sulfurization of the first wiring 3 and the second wiring 5 is suppressed.

[0056] When an aggregate substrate in which a plurality of ceramic substrates 2 are aligned in row and column directions is used, after the metal layer is formed, the aggregate substrate is cut to separate the individual wiring substrates 1a. The cutting can be performed, for example, by a laser or a blade.

[0057] Second embodiment A wiring board 1b according to the second embodiment and a manufacturing method thereof will be described with reference to FIGS.

[0058] The wiring board 1b of the second embodiment differs from the wiring board 1a of the first embodiment in that the side surface 23 of the ceramic substrate 2 further has a third side surface 23c between the first side surface 23a and the second side surface 23b, the lower surface 22 of the ceramic substrate 2 further has a third lower surface 22c that is located more inward than the second lower surface 22b, has a second lower surface 22b between the second side surface 23b and the third side surface 23c, has the third lower surface 22c continuous with the third side surface 23c, and the first wiring 3 is continuously arranged in contact with the second side surface 23b, the second lower surface 22b, the third side surface 23c, and the third lower surface 22c.

[0059] The side surface 31 of the first wiring 3 and the first side surface 23a of the ceramic substrate 2 are preferably on the same plane.

[0060] In wiring board 1b, the area of ​​first wiring 3 on the side surface is large, and therefore the contact area of ​​solder when connecting to other components, for example, a mounting board, is large, resulting in high adhesion and thermal conductivity.

[0061] The manufacturing method of the wiring board 1b according to the second embodiment differs from the manufacturing method of the wiring board 1a according to the first embodiment in that it includes the following: (a) in preparing a ceramic substrate, the ceramic substrate 2 further has a third side surface 23c between the first side surface 23a and the second side surface 23b, the lower surface 22 of the ceramic substrate 2 further has a third lower surface 22c that is more inward than the second lower surface 22b, the second lower surface 22b is between the second side surface 23b and the third side surface 23c, and the third lower surface 22c is continuous with the third side surface 23c; and (b) in forming a first conductive paste layer 41, the first conductive paste layer 41 is formed so as to be continuously arranged in contact with the second side surface 23b, the second lower surface 22b, the third side surface 23c, and the third lower surface 22c.

[0062] Third embodiment A wiring board 1c according to the third embodiment will be described with reference to FIGS.

[0063] The wiring board 1c according to the third embodiment is different from the wiring board 1b according to the second embodiment in that the side surface 23 of the ceramic substrate 2 further has a fourth side surface 23d between the first side surface 23a and the third side surface 23c, the lower surface 22 of the ceramic substrate 2 further has a fourth lower surface 22d inside the third lower surface 22c, the first wiring 3 is not disposed on the fourth side surface 23d and the fourth lower surface 22d, and the first metal layer 4 is also disposed on the side surface 33 of the first wiring 3. In the wiring board 1c, the first wiring 3 is continuously disposed in contact with the second side surface 23b, the second lower surface 22b, the third side surface 23c, and the third lower surface 22c.

[0064] By disposing the first metal layer 4 on the side surface 33 of the first wiring 3, the solder wettability to the side surface of the wiring board is improved, and heat dissipation is improved.

[0065] The side surface 33 of the first wiring 3 and the fourth side surface 23d of the ceramic substrate 2 are preferably on the same plane.

[0066] The manufacturing method of the wiring board 1c of the third embodiment differs from the manufacturing method of the wiring board 1b of the second embodiment in that (a) in preparing the ceramic substrate 2, the ceramic substrate 2 is further prepared so as to have a fourth side surface 23d between the first side surface 23a and the third side surface 23c, and the lower surface 22 of the ceramic substrate 2 is further prepared so as to have the fourth lower surface 22d inside the third lower surface 22c; (b) in forming the first conductive paste layer 41, the first conductive paste is formed so as not to be placed on the fourth side surface 23d and the fourth lower surface 22d; and (e) in forming a metal layer on the wiring, before forming the first metal layer 4, a half cut is made on the first wiring 3 to a depth reaching the ceramic substrate, and the first metal layer 4 is also placed in the half cut portion.

[0067] (Fourth embodiment) A wiring board 1d according to the fourth embodiment and a manufacturing method thereof will be described with reference to Fig. 10 and Fig. 11A to Fig. 11C. Fig. 10 is a schematic bottom view of the wiring board 1d.

[0068] The wiring board 1d of the fourth embodiment is rectangular when viewed from above, and differs from the wiring board 1a of the first embodiment in that the side surfaces of the wiring board 1d include a front surface 11, a right side surface 12 and a left side surface 13 adjacent to the front surface 11, and a back surface 14 opposite the front surface 11 and adjacent to the right side surface 12 and the left side surface 13, and the first wiring 3 is present on the right side surface 12 and the left side surface 13, but not on the front surface 11 or the back surface 14.

[0069] The manufacturing method of the wiring board 1d of the fourth embodiment differs from the manufacturing method of the wiring board 1a of the first embodiment in that (a) in preparing a ceramic substrate 2, a ceramic substrate 2 is prepared in which a first lower surface 22a is further disposed along the front surface 35 and the back surface 36 of the ceramic substrate 2.

[0070] (Variation 1) Fig. 12 is a schematic cross-sectional view of a wiring board 1e according to Modification 1. As shown in Fig. 12, the wiring board 1e according to Modification 1 is different from the wiring board 1a according to the first embodiment in that the ceramic substrate 2 has a through hole 29 connecting the second upper surface 21b and the second lower surface 22b, and the first wiring 3 and the second wiring 5 are connected by a conductor 7 arranged in the through hole 29. The aspect of Modification 1 is applicable to any of the first to fourth embodiments.

[0071] The manufacturing method of the wiring board 1e of the first variant example differs from the manufacturing method of the wiring board 1a of the first embodiment in that (a) in preparing the ceramic substrate 2, a ceramic substrate 2 having a through hole 29 connecting the second lower surface 22b and the second upper surface 21b is further prepared, and (b) in forming the first conductive paste layer 41 and the second conductive paste layer 42, a third conductive paste layer is further formed connecting the first conductive paste layer 41 and the second conductive paste layer 42.

[0072] Fifth embodiment A composite substrate 101a according to the fifth embodiment will be described with reference to FIG.

[0073] Composite substrate 101a includes a first component 61 and a connection member 64 that electrically connects first wiring 3 of wiring substrate 1e and first component 61.

[0074] The first component 61 is typically a mounting board. The mounting board used as the first component 61 has a board 62 and wiring 63. The connection member 64 electrically connects the wiring 63 of the mounting board and the first wiring 3 of the wiring board 1e. In the composite board 101a, the connection member 64 is arranged so as to contact both the first metal layer 4 and the side of the first wiring 3. By arranging the connection member 64 up to the side of the first wiring 3, the contact area between the connection member 64 and the wiring board 1e is increased, and the connection strength and thermal conductivity are improved. Note that, when the first metal layer 4 does not exist, the connection member 64 is arranged so as to contact both the lower surface of the first wiring 3 and the side of the first wiring 3.

[0075] The connection member 64 may be solder, a metal paste, or a conductive adhesive, with solder being preferred.

[0076] Sixth embodiment A composite substrate 101b according to a sixth embodiment will be described with reference to FIG.

[0077] Compared to composite substrate 101a according to the fifth embodiment, composite substrate 101b according to the sixth embodiment further includes second component 71, and connection member 65 electrically connects second metal layer 6 and second component 71. Note that in the absence of second metal layer 6, connection member 65 electrically connects an upper surface of second wiring 5 and second component 71.

[0078] The second component 71 may be a light-emitting element. The light-emitting element used as the second component 71 is a member that emits light when power is supplied. The light-emitting element has a rectangular shape in plan view, for example. The light-emitting element includes a semiconductor laminate, and here, a light-transmitting substrate such as sapphire or gallium nitride is disposed on the upper surface side of the semiconductor laminate, and has a pair of element electrodes 81 on the lower surface side. Any composition can be used for the semiconductor laminate depending on the desired emission wavelength. For example, a nitride semiconductor (In x Al y Ga 1-x-y N, 0≦X, 0≦Y, X+Y≦1), GaP, or GaAlAs or AlInGaP capable of emitting red light can be used. The size and shape of the light-emitting element can be appropriately selected depending on the purpose of use.

[0079] The pair of element electrodes 81 have, for example, a rectangular shape in plan view and are exposed on the lower surface of the light emitting element. The element electrodes 81 can be made of a single layer or a multilayer film of a metal such as gold, platinum, palladium, rhodium, nickel, tungsten, molybdenum, chromium, titanium, or an alloy thereof.

[0080] Here, the element electrode 81 is connected via a connection member 65 to the second metal layer 6 of the wiring board 1e.

[0081] (Translucent member) The light-transmitting member 82 is a member that protects the upper surface of the light-emitting element used as the second component 71 and is located on the light extraction surface. Here, the light-transmitting member 82 is rectangular, for example, and has a shape and size that encompasses the light-emitting element in a planar view. The light-transmitting member 82 may have the same size and shape as the light-emitting element in a planar view.

[0082] The light-transmitting member 82 is made of, for example, a light-transmitting resin material, and may be, for example, an epoxy resin, a silicone resin, or a resin obtained by mixing these. The light-transmitting member 82 may contain a phosphor, and for example, by containing a phosphor that absorbs blue light from the light-emitting element and emits yellow light, it is possible to emit white light. The light-transmitting member 82 may also contain multiple types of phosphors, and for example, by containing a phosphor that absorbs blue light from the light-emitting element and emits green light and a phosphor that emits red light, it is possible to emit white light.

[0083] The light-transmitting member 82 may further include a light-emitting material such as a phosphor or quantum dots. Examples of such phosphors include yttrium aluminum (gallium-doped) garnet activated with cerium, nitrogen-containing calcium aluminosilicate (strontium) activated with europium, potassium fluorosilicate activated with manganese, and β-sialon phosphors. Specific examples of phosphors include yttrium aluminum garnet phosphors (e.g., (Y,Gd)3(Al,Ga)5O 12 :Ce), lutetium aluminum garnet phosphors (e.g., Lu3(Al,Ga)5O 12 :Ce), terbium aluminum garnet phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), CCA phosphors (e.g., Ca 10 (PO4)6Cl2:Eu), SAE phosphors (e.g., Sr4Al 14 O 25 :Eu), chlorosilicate phosphors (e.g., Ca8MgSi4O 16 Cl2:Eu), silicate phosphors (e.g., (Ba,Sr,Ca,Mg)2SiO4:Eu), β-sialon phosphors (e.g., (Si,Al)3(O,N)4:Eu) or α-sialon phosphors (e.g., Ca(Si,Al) 12 (O,N) 16 :Eu) and other oxynitride phosphors, LSN phosphors (e.g., (La,Y)3Si6N 11:Ce), BSESN-based phosphors (e.g., (Ba,Sr)2Si5N8:Eu), SLA-based phosphors (e.g., SrLiAl3N4:Eu), CASN-based phosphors (e.g., CaAlSiN3:Eu), or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), etc. nitride-based phosphors, KSF-based phosphors (e.g., K2SiF6:Mn), KSAF-based phosphors (e.g., K2(Si 1-x Al x )F 6-x :Mn, where x satisfies 0 < x < 1.), or fluoride-based phosphors such as MGF-based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn), etc. Quantum dots include quantum dots having a perovskite structure (e.g., (Cs,FA,MA)(Pb,Sn)(F,Cl,Br,I)3, where FA represents formamidinium and MA represents methylammonium.), II-VI group quantum dots (e.g., CdSe), III-V group quantum dots (e.g., InP), quantum dots having a chalcopyrite structure (e.g., (Ag,Cu)(In,Ga)(S,Se)2), etc.

[0084] (Covering member) The covering member 83 is disposed on the upper surface of the wiring substrate 1e and covers and protects the side surfaces of the light-emitting element used as the second component 71 and the translucent member 82. The covering member 83 is disposed with the upper surface of the translucent member 82 exposed. Further, the covering member 83 enters between the light-emitting element and the wiring substrate 1e to also cover the side surfaces of the element electrode 81 and the connection member 65.

[0085] The covering member 83 can be formed of a resin having any of light reflectivity, light transmission, light blocking properties, etc., or a resin containing a light reflecting substance or a light blocking substance in such a light transmitting resin. The covering member 83 preferably has at least either light reflectivity or light blocking properties. Examples of the resin include a resin containing one or more of silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, and acrylic resin, or a hybrid resin. Examples of the light reflecting substance include titanium oxide, silicon oxide, zirconium oxide, potassium titanate, aluminum oxide, aluminum nitride, boron nitride, and mullite. The covering member 83 may contain a phosphor, a diffusing material, a colorant, etc.

[0086] Embodiments of the present disclosure include the following: [Section 1] a ceramic substrate having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located more inward than the first lower surface, and the side surface having an outermost first side surface and an innermost second side surface on the lower surface side; a first wiring having a thickness of 80% or more of a height from the second lower surface to the first lower surface and arranged in contact with the second lower surface and the second side surface; a side surface of the first wiring is exposed from the first side surface of the ceramic substrate; A wiring board, wherein a main surface of the first wiring, which accounts for 50% or more of the surface area of ​​the lower surface of the first wiring, is substantially parallel to the second lower surface and is disposed more inward than the first lower surface. [Section 2] The upper surface of the ceramic substrate has a first upper surface and a second upper surface located more inward than the first upper surface, Item 2. The wiring board according to item 1, further comprising: a second wiring having a thickness of 80% or more of the height from the second upper surface to the first upper surface and arranged in contact with the second upper surface. [Section 3] The side surface of the ceramic substrate further includes a third side surface between the first side surface and the second side surface, The lower surface of the ceramic substrate further includes a third lower surface located more inward than the second lower surface, The second lower surface is between the second side surface and the third side surface, The third lower surface is continuous with the third side surface, 3. The wiring board according to item 1 or 2, wherein the first wiring is continuously arranged in contact with the second side surface, the second lower surface, the third side surface, and the third lower surface. [Section 4] Item 4. The wiring board according to any one of items 1 to 3, wherein the main surface of the lower surface of the first wiring is disposed 0.4 μm to 5.0 μm inward from the first lower surface. [Section 5] The side surface of the ceramic substrate further includes a fourth side surface between the first side surface and the third side surface, The lower surface of the ceramic substrate further has a fourth lower surface located more inward than the third lower surface, 5. The wiring board according to item 3 or 4, wherein the first wiring is not disposed on the fourth side surface and the fourth lower surface. [Section 6] the wiring substrate further includes a first metal layer disposed on the lower surface of the first wiring, Item 2. The wiring board according to item 1, wherein the surface of the first metal layer and the first lower surface are flush with each other. [Section 7] 7. The wiring board according to any one of claims 2 to 6, further comprising a second metal layer disposed on an upper surface of the second wiring. [Section 8] 8. The wiring board according to claim 1, wherein the first wiring and the first lower surface are spaced apart from each other. [Section 9] 9. The wiring board according to any one of items 2 to 8, wherein the second wiring and the first upper surface are spaced apart from each other. [Section 10] The wiring board has a rectangular shape when viewed from above, the side surface of the wiring board includes a front surface, a right side surface and a left side surface adjacent to the front surface, and a back surface opposite the front surface and adjacent to the right side surface and the left side surface; 10. The wiring board according to any one of items 1 to 9, wherein the first wiring is present on the front surface, the right side surface, the left side surface, and the back surface. [Section 11] The wiring board has a rectangular shape when viewed from above, the side surface of the wiring board includes a front surface, a right side surface and a left side surface adjacent to the front surface, and a back surface opposite the front surface and adjacent to the right side surface and the left side surface; 10. The wiring board according to any one of items 1 to 9, wherein the first wiring is present on the right side surface and the left side surface, and is not present on the front surface and the back surface. [Section 12] In a cross-sectional view in a thickness direction of the ceramic substrate, a first corner portion defined by the first lower surface and the second side surface is rounded; Item 10. The wiring board according to any one of items 1 to 9, wherein the first metal layer covers the first corner portion. [Section 13] In a cross-sectional view in a thickness direction of the ceramic substrate, a second corner portion defined by the first upper surface and a fifth side surface connecting the first upper surface and the second upper surface is rounded; Item 10. The wiring board according to any one of items 2 to 9, wherein the second metal layer covers the second corner portion. [Section 14] Item 14. The wiring board according to any one of items 1 to 13, A first part; a connection member that electrically connects the first wiring of the wiring board and the first component. [Section 15] the wiring substrate further includes a first metal layer disposed on the lower surface of the first wiring, Item 15. The composite substrate according to item 14, wherein the connection member is arranged so as to contact the lower surface of the first wiring, or both the first metal layer and the side surface of the first wiring. [Section 16] the wiring board further includes a second metal layer disposed on an upper surface of the second wiring; The composite substrate further includes a second component; Item 16. The composite substrate according to item 15, wherein the connection member electrically connects the upper surface of the second wiring or the second metal layer to the second component. [Section 17] preparing a ceramic substrate having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located more inward than the first lower surface, and the side surface having an outermost first side surface and an innermost second side surface on the lower surface side; disposing a first conductive paste on the second lower surface to form a first conductive paste layer; Firing the first conductive paste layer to form a first wiring intermediate body; polishing or grinding the first wiring intermediate body to form a first wiring having a main surface that accounts for 50% or more of the surface area of ​​a lower surface of the first wiring substantially parallel to the second lower surface and disposed inwardly of the first lower surface; A method for manufacturing a wiring board, wherein, in forming the first wiring, the first wiring has a thickness that is 80% or more of the height from the second lower surface to the first lower surface, is arranged in contact with the second lower surface and the second side surface, and a side surface of the first wiring is exposed from the first side surface of the ceramic substrate. [Section 18] The step of preparing the ceramic substrate further includes preparing the ceramic substrate having a first upper surface and a second upper surface located on the inner side of the first upper surface; After preparing the ceramic substrate, a second conductive paste is further disposed on the second upper surface to form a second conductive paste layer; Item 18. The method for manufacturing a wiring board according to item 17, wherein forming the first wiring intermediate body includes firing the second conductive paste layer to form a second wiring intermediate body. [Section 19] After forming the second wiring intermediate body, the second wiring intermediate body is polished or ground to form a second wiring having a second upper surface located inside the first upper surface, Item 19. The method for manufacturing a wiring board according to item 18, wherein in forming the second wiring, the second wiring has a thickness of 80% or more of the height from the second upper surface to the first upper surface and is arranged in contact with the second upper surface. [Section 20] In preparing the ceramic substrate, the ceramic substrate further includes a third side surface between the first side surface and the second side surface, the lower surface of the ceramic substrate further includes a third lower surface located more inward than the second lower surface, the second lower surface is between the second side surface and the third side surface, and the third lower surface is continuous with the third side surface; 20. The method for manufacturing a wiring board according to any one of claims 17 to 19, further comprising forming the first conductive paste layer so as to be continuously arranged in contact with the second side surface, the second lower surface, the third side surface, and the third lower surface. [Section 21] 21. The method for manufacturing a wiring board according to any one of claims 17 to 20, wherein in forming the first wiring, the first wiring intermediate body is polished or ground so that the main surface of the lower surface of the first wiring is positioned at least 0.4 μm or more inward from the first lower surface. [Section 22] In preparing the ceramic substrate, the ceramic substrate further includes a fourth side surface between the first side surface and the third side surface, and the lower surface of the ceramic substrate further includes a fourth lower surface located more inward than the third lower surface; Item 22. The method for manufacturing a wiring board according to item 20 or 21, wherein in forming the first conductive paste layer, the first conductive paste is formed so as not to be positioned on the fourth side surface and the fourth lower surface. [Section 23] After forming the first wiring, the method further includes forming a first metal layer on the lower surface of the first wiring; Item 23. The method for manufacturing a wiring board according to any one of items 17 to 22, wherein in forming the first metal layer, the first metal layer is formed so that the surface of the first metal layer and the first lower surface are flush with each other. [Section 24] Item 24. The method for manufacturing a wiring board according to any one of items 19 to 23, further comprising forming a second metal layer on an upper surface of the second wiring after forming the second wiring. [Section 25] Item 25. The method for manufacturing a wiring board according to item 24, wherein in forming at least one of the first metal layer and the second metal layer, at least one of the first metal layer and the second metal layer is formed by plating. [Section 26] Item 26. The method for manufacturing a wiring board according to item 25, wherein in forming at least one of the first metal layer and the second metal layer, an edge portion of at least one of the first metal layer and the second metal layer is further pressed. [Explanation of symbols]

[0087] 1a, 1b, 1c, 1d, 1e...Wiring board 2...ceramic substrate, 3...first wiring, 4...first metal layer, 4a...surface of first metal layer 5... second wiring, 6... second metal layer, 6a... surface of second metal layer, 7... conductor 11: front side of wiring board; 12: right side of wiring board; 13: left side of wiring board, 14: rear side of wiring board 21... upper surface of ceramic substrate, 21a... first upper surface, 21b... second upper surface 21c...Third top surface, 21d...Fourth top surface 22...lower surface of ceramic substrate, 22a...first lower surface, 22b...second lower surface 22c...Third bottom surface, 22d...Fourth bottom surface 23...side surface of ceramic substrate, 23a...first side surface, 23b...second side surface 23c…3rd side, 23d…4th side 24... fifth side surface of ceramic substrate, 25... recess, 26... first arrangement portion 27...First corner, 28...Second corner, 29...Through hole 31: side surface of first wiring; 32: lower surface of first wiring; 33: side surface of first wiring 35: front surface of ceramic substrate; 36: rear surface of ceramic substrate 41: first conductive paste layer, 42: second conductive paste layer 43: first wiring intermediate body; 44: second wiring intermediate body; 51: Lower surface of second wiring; 52: Upper surface of second wiring 61: first component; 62: circuit board; 63: wiring; 64...connecting member, 65...connecting member 71: second component, 81: element electrode, 82: light-transmitting member, 83: covering member 101a,101b...Composite board

Claims

1. a ceramic substrate having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located more inward than the first lower surface, and the side surface having an outermost first side surface and an innermost second side surface on the lower surface side; a first wiring having a thickness of 80% or more of a height from the second lower surface to the first lower surface and arranged in contact with the second lower surface and the second side surface; a side surface of the first wiring is exposed from the first side surface of the ceramic substrate, A wiring board, wherein a main surface of the first wiring, which accounts for 50% or more of a surface area of ​​a lower surface of the first wiring, is substantially parallel to the second lower surface and is disposed more inward than the first lower surface.

2. The upper surface of the ceramic substrate has a first upper surface and a second upper surface located more inward than the first upper surface, 2 . The wiring board according to claim 1 , further comprising: a second wiring having a thickness of 80% or more of a height from said second upper surface to said first upper surface, said second wiring being disposed in contact with said second upper surface.

3. The side surface of the ceramic substrate further includes a third side surface between the first side surface and the second side surface, The lower surface of the ceramic substrate further includes a third lower surface located on the inner side of the second lower surface, The second lower surface is between the second side surface and the third side surface, The third lower surface is continuous with the third side surface, The wiring board according to claim 1 , wherein the first wiring is disposed continuously in contact with the second side surface, the second lower surface, the third side surface, and the third lower surface.

4. The wiring board according to claim 1 , wherein the main surface of the lower surface of the first wiring is located 0.4 μm to 5.0 μm inward from the first lower surface.

5. The side surface of the ceramic substrate further includes a fourth side surface between the first side surface and the third side surface, The lower surface of the ceramic substrate further includes a fourth lower surface located more inward than the third lower surface, The wiring board according to claim 3 , wherein the first wiring is not disposed on the fourth side surface or the fourth lower surface.

6. the wiring substrate further includes a first metal layer disposed on the lower surface of the first wiring, The wiring board according to claim 1 , wherein the surface of the first metal layer and the first lower surface are flush with each other.

7. The wiring board according to claim 2 , further comprising a second metal layer disposed on an upper surface of the second wiring.

8. The wiring board according to claim 1 , wherein the first wiring and the first lower surface are spaced apart from each other.

9. The wiring board according to claim 2 , wherein the second wiring and the first upper surface are spaced apart from each other.

10. The wiring board has a rectangular shape when viewed from above, the side surface of the wiring board includes a front surface, a right side surface and a left side surface adjacent to the front surface, and a back surface opposite the front surface and adjacent to the right side surface and the left side surface; The wiring board according to claim 1 , wherein the first wiring is present on the front surface, the right side surface, the left side surface, and the back surface.

11. The wiring board has a rectangular shape when viewed from above, the side surface of the wiring board includes a front surface, a right side surface and a left side surface adjacent to the front surface, and a back surface opposite the front surface and adjacent to the right side surface and the left side surface; The wiring board according to claim 1 , wherein the first wiring is present on the right side surface and the left side surface, and is not present on the front surface and the back surface.

12. In a cross-sectional view in a thickness direction of the ceramic substrate, a first corner defined by the first lower surface and the second side surface is rounded; The wiring board according to claim 6 , wherein the first metal layer covers the first corner portion.

13. In a cross-sectional view in a thickness direction of the ceramic substrate, a second corner portion defined by the first upper surface and a fifth side surface connecting the first upper surface and the second upper surface is rounded, The wiring board according to claim 7 , wherein the second metal layer covers the second corner portion.

14. The wiring board according to claim 1 ; A first part; a connection member that electrically connects the first wiring of the wiring board and the first component.

15. the wiring substrate further includes a first metal layer disposed on the lower surface of the first wiring, The composite substrate according to claim 14 , wherein the connection member is disposed so as to contact the lower surface of the first wiring, or to contact both the first metal layer and the side surface of the first wiring.

16. the wiring board further includes a second metal layer disposed on an upper surface of the second wiring; The composite substrate further includes a second component; The composite substrate according to claim 15 , wherein the connection member electrically connects the upper surface of the second wiring or the second metal layer to the second component.

17. preparing a ceramic substrate having an upper surface, a lower surface opposite to the upper surface, and a side surface between the upper surface and the lower surface, the lower surface having an outermost first lower surface and a second lower surface located more inward than the first lower surface, and the side surface having an outermost first side surface and an innermost second side surface on the lower surface side; disposing a first conductive paste on the second lower surface to form a first conductive paste layer; Firing the first conductive paste layer to form a first wiring intermediate body; polishing or grinding the first wiring intermediate body to form a first wiring having a main surface that accounts for 50% or more of a surface area of ​​a lower surface of the first wiring substantially parallel to the second lower surface and disposed inwardly of the first lower surface; A method for manufacturing a wiring board, wherein, in forming the first wiring, the first wiring has a thickness that is 80% or more of the height from the second lower surface to the first lower surface, is arranged in contact with the second lower surface and the second side surface, and a side surface of the first wiring is exposed from the first side surface of the ceramic substrate.

18. The step of preparing the ceramic substrate further includes preparing the ceramic substrate having a first upper surface and a second upper surface located on the inner side of the first upper surface; After preparing the ceramic substrate, a second conductive paste is further disposed on the second upper surface to form a second conductive paste layer; 18. The method for manufacturing a wiring board according to claim 17, wherein forming the first wiring intermediate body includes firing the second conductive paste layer to form a second wiring intermediate body.

19. After forming the second wiring intermediate body, the second wiring intermediate body is polished or ground to form a second wiring having a second upper surface located inside the first upper surface, 20. The method for manufacturing a wiring board according to claim 18, wherein in forming the second wiring, the second wiring has a thickness that is 80% or more of a height from the second upper surface to the first upper surface, and is disposed in contact with the second upper surface.

20. In preparing the ceramic substrate, the ceramic substrate further includes a third side surface between the first side surface and the second side surface, the lower surface of the ceramic substrate further includes a third lower surface located more inward than the second lower surface, the second lower surface is between the second side surface and the third side surface, and the third lower surface is continuous with the third side surface; 18. The method for manufacturing a wiring board according to claim 17, further comprising forming the first conductive paste layer so as to be continuously arranged in contact with the second side surface, the second lower surface, the third side surface, and the third lower surface.

21. 18. The method for manufacturing a wiring board according to claim 17, wherein in forming the first wiring, the first wiring intermediate body is polished or ground so that the main surface of the lower surface of the first wiring is positioned at least 0.4 μm or more inward from the first lower surface.

22. In preparing the ceramic substrate, the ceramic substrate further includes a fourth side surface between the first side surface and the third side surface, and the lower surface of the ceramic substrate further includes a fourth lower surface located more inward than the third lower surface; The method for manufacturing a wiring board according to claim 20 , wherein in forming the first conductive paste layer, the first conductive paste layer is formed such that the first conductive paste is not disposed on the fourth side surface and the fourth lower surface.

23. After forming the first wiring, the method further includes forming a first metal layer on the lower surface of the first wiring; The method for manufacturing a wiring board according to claim 17 , wherein, in forming the first metal layer, the first metal layer is formed so that the surface of the first metal layer and the first lower surface are flush with each other.

24. 20. The method for manufacturing a wiring board according to claim 19, further comprising, after forming the second wiring, forming a second metal layer on an upper surface of the second wiring.

25. 25 . The method for manufacturing a wiring board according to claim 24 , wherein in forming at least one of the first metal layer and the second metal layer, at least one of the first metal layer and the second metal layer is formed by plating.

26. 26. The method for manufacturing a wiring board according to claim 25, further comprising the step of pressing an edge portion of at least one of the first metal layer and the second metal layer in forming at least one of the first metal layer and the second metal layer.

Images