Wiring board and light emitting device manufacturing method

Abstract

To provide a manufacturing method of a wiring board capable of forming a wiring to which a metal particle is sintered at a low temperature, and provide a manufacturing method of a light-emitting device.SOLUTION: A manufacturing method of a wiring board contains steps of: preparing a base material 10 in which a hole part where one part of a first surface 10A and a second surface 10B of the base material 10 is exposed is formed in a resist part 30; filling a paste member 40 containing a metal particle into the hole part of the resist part 30; and sintering the past member 40 at a temperature of 150°C or more and lower than a melting point of the metal particle. In the step of preparing the base material 10, the hole part is formed so that a width LM2 of an inner bottom surface of the hole part becomes larger than a width LM1 of an opening, and the metal particle is a copper particle with a predetermined particle diameter. The paste member 40 is heated to a predetermined temperature in a vacuum or a nitrogen atmosphere under a predetermined pressure in the sintering of the paste member 40. By sintering the metal particles, a wiring is formed to as to be a shape along the inner bottom surface and an inner side surface of the hole part, and the wiring is electrically connected.SELECTED DRAWING: Figure 2C

Description

[Technical Field]

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

[0002] There is a known technology for sintering small metal particles at a low temperature to form wiring, etc. For example, Patent Document 1 describes an electromagnetic shielding material in which metal powders with an average particle size of 0.1 nm to 100 nm are fused together at a low temperature of 100°C to 250°C to form a lattice-like pattern or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-172283 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 substrate and a light emitting device capable of forming wiring by low-temperature sintering of metal particles, as well as methods for manufacturing the same. [Means for solving the problem]

[0005] The wiring board disclosed in the embodiment comprises an insulating base material having a first surface and a second surface opposite to the first surface, a resist portion arranged to cover at least a portion of the first surface and the second surface of the base material and having holes of a predetermined pattern, and wiring arranged in the holes of the resist portion so as to contact the base material, wherein, when viewed in a cross-sectional view in the thickness direction of the base material, the length of the exposed surface of the wiring exposed from the resist portion is shorter than the length of the contact surface in contact with the base material.

[0006] A light emitting device disclosed in the embodiment includes the wiring board disclosed in the embodiment, and a light source including a light emitting element disposed on the wiring board.

[0007] Furthermore, a method for manufacturing a wiring board disclosed in an embodiment includes the steps of: preparing an insulating substrate having a first surface and a second surface opposite to the first surface, wherein a resist portion is arranged to cover at least one of the first surface and the second surface of the substrate, and a hole portion is formed in the resist portion such that a portion of the first surface and the second surface of the substrate is exposed through the resist portion; filling the hole portion in the resist portion with a paste material containing metal particles; and firing the paste material at a temperature of 150°C or higher and lower than the melting point of the metal particles; wherein, in preparing the substrate, the hole portion is formed so that the width of the inner bottom surface of the hole is larger than the width of the opening; and, in firing the paste material, the metal particles are sintered to form wiring in a shape that follows the inner bottom surface and inner side surface of the hole, and the wiring is electrically connected.

[0008] Furthermore, the manufacturing method of the light-emitting device disclosed in the embodiment includes manufacturing a wiring board by the manufacturing method of the wiring board disclosed in the embodiment, arranging a light source including a light-emitting element on the wiring board, and electrically connecting the light-emitting element and the wiring board with a conductive connecting member. [Effects of the Invention]

[0009] According to the embodiments of the present disclosure, it is possible to provide a wiring substrate and a light emitting device capable of forming wiring by low-temperature sintering of metal particles, as well as methods for manufacturing the same. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view schematically illustrating a cross section of a portion of a wiring board according to an embodiment. [Figure 2A] FIG. 2 is a plan view showing a part of a wiring substrate according to an embodiment. [Figure 2B]2B is a cross-sectional view taken along line IIC-IIC in FIG. 2A with wiring removed. [Figure 2C] FIG. 2B is a cross-sectional view taken along line IIC-IIC in FIG. 2A. [Figure 2D] FIG. 2B is a cross-sectional view taken along line IID-IID in FIG. 2A. [Figure 2E] FIG. 2 is an explanatory diagram illustrating a partially enlarged cross section of a wiring. [Figure 3] 1 is a flowchart illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4A] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4B] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4C] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4D] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4E] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 4F] FIG. 4E is a cross-sectional view illustrating the plate removed. [Figure 4G] 1A to 1C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment. [Figure 5A] FIG. 2 is a plan view illustrating a part of the photomask on the first surface side. [Figure 5B] FIG. 2 is a plan view illustrating a part of the photomask on the second surface side. [Figure 6A] 1 is a perspective view illustrating a light emitting device according to a first embodiment. [Figure 6B] FIG. 1 is a plan view illustrating a light emitting device according to a first embodiment. [Figure 6C] 3 is a plan view illustrating an example of a wiring substrate of the light emitting device according to the first embodiment. FIG. [Figure 6D] FIG. 6C is a cross-sectional view taken along line VID-VID in FIG. 6B. [Figure 7A] FIG. 2 is a perspective view illustrating a light source of the light emitting device according to the embodiment. [Figure 7B] FIG. 2 is a plan view illustrating a light source of the light emitting device according to the embodiment. [Figure 7C] FIG. 2 is a bottom view illustrating a light source of the light emitting device according to the embodiment. [Figure 7D] FIG. 7C is a cross-sectional view taken along line VIID-VIID in FIG. 7B. [Figure 8] 4 is a flowchart illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 9A] 3A to 3C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 9B] 3A to 3C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 9C] 3A to 3C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 9D] 3A to 3C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 10A] FIG. 10 is a plan view illustrating the light emitting device according to the second embodiment. [Figure 10B] FIG. 10 is a plan view illustrating a part of the light emitting device according to the second embodiment. [Figure 10C] 10C is a plan view illustrating a part of the wiring substrate of the light emitting device according to the second embodiment, corresponding to FIG. 10B. FIG. [Figure 10D] FIG. 10C is a cross-sectional view taken along line XD-XD in FIG. 10B. [Figure 11] 10 is a flowchart illustrating a method for manufacturing a light emitting device according to a second embodiment. [Figure 12A] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. [Figure 12B] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. [Figure 12C] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. [Figure 12D] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. [Figure 12E] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. [Figure 12F] 6A to 6C are cross-sectional views illustrating a method for manufacturing the light emitting device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. However, the embodiments described below are intended to embody the technical ideas of the present disclosure, and unless otherwise specified, the invention is not limited to the following. The content described in one embodiment can also be applied to other embodiments and modified examples. Furthermore, the drawings are schematic illustrations of the embodiments, and for clarity of explanation, the scale, spacing, positional relationships, etc. of each component may be exaggerated, or some components may be omitted. The directions shown in each figure indicate the relative positions between components and are not intended to indicate absolute positions. In principle, the same names and symbols indicate components that are identical or of the same quality, and detailed explanations will be omitted as appropriate. Furthermore, in the embodiments, "cover" does not only refer to direct contact, but also includes indirect covering, for example, via another component.

[0012] [Wiring board] A wiring board 1 according to the embodiment will be described with reference to FIGS. 1 to 2E. FIG. 1 is a perspective view schematically showing a cross section of a portion of wiring board 1. FIG. 2A is a plan view showing a portion of wiring board 1. FIG. 2B is a cross section taken along line IIC-IIC in FIG. 2A, with wiring 40 removed. FIG. 2C is a cross section taken along line IIC-IIC in FIG. 2A. FIG. 2D is a cross section taken along line IID-IID in FIG. 2A. FIG. 2E is an explanatory diagram schematically showing an enlarged portion of the cross section of wiring 40.

[0013] The wiring board 1 includes an insulating base material 10 having a first surface 10A and a second surface 10B opposite to the first surface 10A, a resist portion 30 arranged to cover at least a portion of the first surface 10A and the second surface 10B of the base material 10 and having holes 35 in a predetermined pattern, and wiring 40 arranged in the holes of the resist portion 30 so as to contact the base material 10, wherein, in a cross-sectional view in the thickness direction of the base material 10, the length of an exposed surface 48 of the wiring 40 exposed from the resist portion 30 is shorter than the length of a contact surface 46 in contact with the base material 10. The wiring board 1 also includes a via conductive portion 50 that electrically connects the wiring 40 between the first surface 10A and the second surface 10B. As an example, wiring board 1 is a rigid board that is used without being bent. Each component of wiring board 1 will be described below.

[0014] (base material) The substrate 10 is an insulating plate-like member that serves as the base of the wiring board 1. The substrate 10 has a first surface 10A and a second surface 10B opposite to the first surface 10A. The first surface 10A and the second surface 10B are both surfaces of the substrate 10. The thickness of the substrate 10 is not particularly limited, and can be, for example, 60 μm or more and 500 μm or less. The material of the substrate 10 may be, for example, a combination of glass fiber and epoxy resin, or a resin material such as ceramics, glass, or phenolic resin, or may be a laminate of these. The surface state of the substrate 10 is not particularly limited, and may be subjected to plasma treatment or roughening treatment, or the surface of the substrate 10 may be coated with an adhesive resin, a silane coupling agent, or the like to improve adhesion with the resist portion 30 and the wiring 40.

[0015] (Register section) The resist portion 30 is an insulating member disposed on the surface of the base material 10. The resist portion 30 covers at least a portion of the first surface 10A and the second surface 10B of the base material 10. The resist portion 30 has holes 35 in a predetermined pattern. The resist portion 30 may be provided only on the first surface 10A, only on the second surface 10B, or on both the first surface 10A and the second surface 10B. The thickness of the resist portion 30 is not particularly limited, and may be, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 25 μm or less.

[0016] The resist portion 30 can be made of a material used for solder resist. For example, a common material made by mixing a solvent, an antifoaming agent, etc. with a copolymer resin such as epoxy, or a material made white by adding a filler such as titanium oxide can be used. The color of the resist portion 30 is not particularly limited, but if a light source or the like is disposed on the wiring board 1 to form a light-emitting device, making the resist portion 30 white can improve light reflectivity.

[0017] (hole) The hole portion 35 is a groove- or hole-shaped through-portion that penetrates the resist portion 30. The hole portion 35 has an inner bottom surface 36, which is the surface of the substrate 10, and inner side surfaces 37 that face each other in a cross-sectional view, with an opening 38 on the opposite side of the substrate 10. In a cross-sectional view of the base material 10 in the thickness direction, the length LH1 of the opening 38 is shorter than the length LH2 of the inner bottom surface 36. Note that the lengths LH1 and LH2 of the opening 38 and the inner bottom surface 36 are the distances parallel to the surface of the base material 10 between the opposing inner sides 37 in a cross-sectional view. In addition, the area of ​​the inner bottom surface 36 is larger than the area of ​​the opening 38 in a plan view.

[0018] In a cross-sectional view in the thickness direction of the substrate 10, the hole 35 is, for example, trapezoidal in shape with the base side on the substrate 10 side being longer. The base angle AH of the trapezoid can be, for example, 40 degrees or more and 80 degrees or less, and preferably 50 degrees or more and 70 degrees or less. A smaller base angle AH is more advantageous in preventing peeling of the wiring 40, but the spacing between adjacent openings 38 becomes wider, which may make it difficult to shorten the distance between the wirings. The hole 35 preferably has an isosceles trapezoidal shape in a cross section in the thickness direction of the base material 10. The inner surface 37 may be curved. In the hole 35, a wiring 40 is arranged.

[0019] (wiring) The wiring 40 is a component that serves as a path for electric current. The wiring 40 is disposed in the hole 35 of the resist section 30 so as to contact the substrate 10. The wiring 40 has a contact surface 46 shaped to fit along the inner bottom surface 36 of the hole 35, an exposed surface 48 exposed from the opening 38 of the hole 35, and a side surface 47 shaped to fit along the inner surface 37 of the hole 35. In a cross-sectional view in the thickness direction of the substrate 10, the wiring 40 has a length LM1 of an exposed surface 48 exposed from the resist portion 30 that is shorter than a length LM2 of a contact surface 46 that is in contact with the substrate 10. The lengths LM1 and LM2 of the exposed surface 48 and the contact surface 46 are the distances parallel to the surface of the substrate 10 between both ends of each surface in a cross-sectional view.

[0020] Similar to the hole 35, the wiring 40 has a trapezoidal shape with the base side on the substrate 10 side being longer when viewed in cross section in the thickness direction of the substrate 10. The size of the base angle AM ​​of the trapezoid can be, for example, 40 degrees or more and 80 degrees or less, and preferably 50 degrees or more and 70 degrees or less. The wiring 40 preferably has an isosceles trapezoidal shape when viewed in cross section in the thickness direction of the base material 10. The side surface 47 may be curved along the inner side surface 37 of the hole .

[0021] The thickness of the wiring 40 in the portion disposed on the upper or lower side of the substrate 10 is preferably the same as the thickness of the resist portion 30. In other words, the total thickness of the wiring 40 is preferably the sum of the thickness of the resist portion 30 on the upper and lower sides of the substrate 10 and the thickness of the substrate 10 itself. The thickness of the wiring 40 in the portion disposed on the upper or lower side of the substrate 10 can be, for example, 5 μm to 50 μm. Furthermore, it is preferable that the thickness of the resist portion 30 be, for example, 20 μm to 30 μm, and the thickness of the wiring 40 in the portion disposed on the upper or lower side of the substrate 10 be 20 μm to 30 μm. The thickness of the wiring 40 in the portion disposed on the upper or lower side of the substrate 10 can be adjusted by the thickness of the resist portion 30. The exposed surface 48 may be recessed or protruded relative to the surface of the resist portion 30, but it is preferable that the exposed surface 48 of the wiring 40 and the surface of the resist portion 30 form a flat surface parallel to the surface of the substrate 10. The width of the wiring 40 can be the same as the width of the hole 35. As an example, in a cross section perpendicular to the longitudinal direction of the wiring 40, the length LM1 of the exposed surface 48 can be 30 μm or more and 300 μm or less, and the length LM2 of the contact surface 46 can be 40 μm or more and 400 μm or less.

[0022] The wiring 40 is formed of a sintered body 41 of metal particles. The wiring 40 differs from wiring in that the metal particles are bonded together to form the sintered body 41, whereas metal particles are fixed in contact or close to each other using a cured binder resin or the like. The wiring 40 does not contain any organic matter, or the organic matter content is 1 wt % or less. Furthermore, as shown in FIG. 2E, the wiring 40 is formed to have voids or bubbles, and includes, for example, multiple bubbles 42 with a diameter of 5 μm or less. The diameter of the bubbles 42 is the diameter of a circle with the same area as the area of ​​the bubbles 42 in the cross section. The wiring 40 may also include bubbles 42 with a diameter greater than 5 μm. The bubbles 42 contained in the wiring 40 preferably account for, for example, 1% to 20% of the total volume. The bubbles 42 are generated when the metal particles are sintered into the sintered body 41. The wiring 40 has low electrical resistance and a volume resistivity of 10 μΩ·cm or less because it is a sintered body 41 of metal particles. The material of the wiring 40 can be, for example, copper or silver.

[0023] (via conduction part) The via conductive portion 50 is a member that connects the wiring 40 between the first surface 10A and the second surface 10B of the substrate 10. The via conductive portion 50 is provided in a through hole that penetrates the substrate 10. In a plan view, the through hole of the substrate 10 can be provided inside the hole portion 35. The via conductive portion 50 and the through hole are not necessary when the resist portion 30 and the wiring 40 are provided on only one surface of the substrate 10, but may be provided for heat dissipation. The via conductive portion 50 and the through hole may have a cylindrical or rectangular shape. The diameter or diagonal length of the through hole may be larger than the length LH1 of the opening 38, but does not exceed the length LH2 of the inner bottom surface 36. The material of the via conductive portion 50 may be the same as that of the wiring 40.

[0024] In wiring board 1, length LM1 of exposed surface 48 is shorter than length LM2 of contact surface 46, so that peeling of wiring 40 is suppressed, and wiring 40 can be made highly reliable. In the wiring board 1, the cross sections of the hole 35 and the wiring 40 are trapezoidal, which can effectively prevent peeling of the wiring 40. In addition, the contact area between the wiring 40 and the base material 10 can be increased, which can improve the heat dissipation effect. By making the cross sections of the hole 35 and the wiring 40 in the shape of an isosceles trapezoid, the inner surface 37 of the hole 35 comes into contact with the wiring 40 in a balanced manner, thereby more effectively preventing the wiring 40 from peeling off.

[0025] The wiring board 1 can be a flexible board using a sheet-like member that can be used by bending the base material 10. When the wiring board 1 is a flexible board, the thickness of the base material 10 can be, for example, 20 μm or more and 100 μm or less. The material of the base material 10 can be, for example, polyimide, polyethylene terephthalate, etc. Note that the wiring board 1 can be a combination of a rigid board and a flexible board that are continuously connected.

[0026] Furthermore, wiring board 1 uses base material 10 made of ceramic, and can be a ceramic board with excellent heat dissipation properties. When the wiring board 1 is a ceramic substrate, the thickness of the base material 10 can be, for example, 100 μm or more and 1000 μm or less. The material of the base material 10 can be, for example, aluminum nitride or silicon nitride.

[0027] [Method of manufacturing wiring board] Next, a method for manufacturing a wiring board according to the embodiment will be described with reference to FIGS. 3 to 5B. FIG. 3 is a flowchart illustrating a method for manufacturing the wiring substrate 1. FIG. 4A is a cross-sectional view illustrating a portion of the base material 10 in which the through-holes 15 are formed. FIG. 4B is a cross-sectional view illustrating a portion of the base material 10 in which the resist portions 30 are formed and the photomasks M1A and M1B. FIG. 4C is a cross-sectional view illustrating a state in which the holes 35 are formed in the resist portions 30. FIG. 4D is a cross-sectional view illustrating a state in which the material for the wiring 40 is disposed in the holes 35. FIG. 4E is a cross-sectional view illustrating a state in which the material for the wiring 40 is heated and pressurized by the plates PL1 and PL2. FIG. 4F is a cross-sectional view illustrating a state in which the plates PL1 and PL2 are removed from FIG. 4E. FIG. 4G is a cross-sectional view illustrating a state in which the surface has been ground. FIG. 5A is a plan view illustrating a portion of the photomask M1A on the first surface 10A side. FIG. 5B is a plan view illustrating a portion of the photomask M1B on the second surface 10B side.

[0028] The method for manufacturing a wiring board includes preparing an insulating substrate 10 having a first surface 10A and a second surface 10B opposite to the first surface 10A, in which a resist portion 30 is arranged so as to cover at least one of the first surface 10A and the second surface 10B of the substrate 10, and a hole portion 35 is formed in the resist portion 30 such that a portion of the first surface 10A and the second surface 10B of the substrate 10 is exposed from the resist portion 30, filling the hole portion 35 of the resist portion 30 with a paste member 60 containing metal particles, and firing the paste member 60 at a temperature of 150°C or higher and lower than the melting point of the metal particles, in S13. In step S11 of preparing the substrate 10, the hole 35 is formed so that the width of the inner bottom surface 36 of the hole 35 is larger than the width of the opening 38, and in step S13 of firing the paste member 60, the metal particles are sintered to form the wiring 40 in a shape that conforms to the inner bottom surface 36 and inner side surface 37 of the hole 35, and the wiring is electrically connected. This method also includes step S14 of polishing or grinding the resist portion 30 and the wiring 40 after firing the paste member 60.

[0029] (Preparing the substrate) In preparing a substrate S11, a resist portion 30 is placed on an insulating substrate 10. A hole portion 35 is formed in the resist portion 30. Preparing a substrate S11 includes forming a through hole 15 in the substrate 10 and placing the resist portion 30 on the substrate 10. Plasma treatment and roughening treatment of the surface of the substrate 10, application of adhesive resin, etc. are performed before placing the resist portion 30. These treatments, applications, etc. can improve adhesion between the surface of the substrate 10 and the resist portion 30 and wiring 40. The through holes 15 are formed at positions where the via conducting portions 50 are to be provided. The through holes 15 can be formed by punching, drilling, laser processing, or the like. The through holes 15 may be formed after the resist portion 30 is disposed. Note that, if the via conducting portions 50 are not provided, the formation of the through holes 15 can be omitted.

[0030] The resist portion 30 forms holes 35 on the substrate 10 so that parts of the first surface 10A and the second surface 10B are exposed. The holes 35 are formed in a pattern that follows predetermined wiring 40. The holes 35 can be formed by photolithography. An example of photolithography will be described. The resist portion 30 uses a material 30A that hardens upon exposure to light. The resist portion material 30A before hardening is applied to the surface of the substrate 10 at a constant thickness. This thickness can be, for example, 5 μm or more and 50 μm or less. The material 30A can be applied by applying an ink-type material by screen printing, or by attaching a dry film-type material. Here, the dry film-type material is applied to both the first surface 10A and the second surface 10B, but it may be applied to the surface on which the wiring 40 is to be provided.

[0031] Next, exposure is performed using a photomask. Photomask M1A is used on the first surface 10A side, and photomask M1B is used on the second surface 10B side. Light-blocking patterns are formed on the photomasks M1A and M1B in the size and shape of the opening 38. The exposure conditions are, for example, a wavelength of the irradiated light L1 of 300 nm or more and 500 nm or less, and an exposure dose of 20 mJ / cm. 2 More than 1000mJ / cm 2 The exposure time can be, for example, 10 seconds or more and 30 seconds or less. After the uncured portion is removed, for example, in an alkaline aqueous solution, the remaining portion is heated to further cure. In this photolithography, by changing the intensity of the light irradiated depending on the translucency of the resist material 30A, it is possible to adjust the size of the inner bottom surface 36 relative to the opening 38 and the base angle of the trapezoidal shape of the hole portion 35 in cross section.

[0032] (Filling with paste material) In step S12 of filling the paste material, the holes 35 are filled with a paste material 60 containing metal particles. This filling can be performed by screen printing, for example, or by gravure printing or spray coating. Here, the paste material 60 is filled simultaneously in the areas where the wiring 40 is to be formed and in the areas where the via conductive portions 50 are to be formed, but it may also be filled separately. The paste material 60 can be filled so that it protrudes from the openings 38 of the holes 35. It should be noted that the paste material 60 may not be selectively filled in the holes 35, but may be printed or applied to the entire surface including the surface of the resist portion 30.

[0033] For example, the paste member 60 contains a reducing organic solvent with a boiling point of 200°C to 300°C in a proportion of 5% to 20% of the weight of the metal particles. The paste member 60 is fired at a temperature of 200°C to 300°C, as described below. By ensuring that the boiling point is within the firing temperature range or a slightly lower temperature range, the organic solvent can be vaporized and removed during firing of the paste member 60. Furthermore, the reducing properties of the organic solvent can suppress oxidation of the metal particles and promote sintering. However, the boiling point of the organic solvent contained in the paste member 60 may be slightly lower than the firing temperature. This is because the organic solvent may vaporize even at temperatures lower than the firing temperature. This is due to factors such as the thickness and size of the paste member 60 and the heat applied to the paste member 60 during firing. Here, the boiling point of the organic solvent contained in the paste member 60, which is in a temperature range slightly lower than the firing temperature, means that the boiling point of the organic solvent may be in a temperature range that is lower than the firing temperature and whose difference from the firing temperature is 80°C or less, or 50°C or less. The paste member 60 may contain a resin with a binder effect, a dispersant that helps disperse metal particles, etc. Also, the paste member 60 may contain a predetermined additive to reduce printing unevenness such as bleeding or blurring.

[0034] The metal particles can be, for example, copper or silver particles or powder. When the metal particles are copper particles, the particle size can be 0.1 μm to 10 μm, preferably 0.1 μm to 7 μm. The proportion of particles with a particle size of 0.1 μm to 1 μm can be 40 wt % to 95 wt %, preferably 50 wt % to 80 wt %. By reducing the particle size of the metal particles to 1 μm or less, sintering can be promoted.

[0035] (Firing the paste material) In firing the paste member S13, the paste member 60 is pressurized and heated to sinter the metal particles to form a sintered body 41. The pressurization and heating can be performed, for example, in the atmosphere, by sandwiching the substrate 10, on which the resist portion 30 is disposed and whose holes 35 are filled with the paste member 60, between two parallel plates. The pressurization and heating conditions are preferably such that the substrate is pressurized at a pressure P1 of 2 MPa to 10 MPa and heated to 200°C to 300°C. Here, after filling both the first surface 10A side and the second surface 10B side of the substrate 10 with the paste material 60, both surfaces are simultaneously pressurized with a pressure P1 by the plates PL1 and PL2 while being heated. Note that after filling one surface with the paste material 60 and applying pressure and heating, the other surface may also be filled with the paste material 60 and applying pressure and heating.

[0036] The pressure application and heating may be carried out in the air, but are preferably carried out in a vacuum or a nitrogen atmosphere, because by carrying out the pressure application and heating in a vacuum or a nitrogen atmosphere, it is possible to suppress the decrease in reflectance due to discoloration of the resist and to further reduce the wiring resistance.

[0037] By applying pressure and heat to the paste member 60, the paste member 60 spreads over the entire trapezoidal inner bottom surface 36 of the hole 35, ensuring a large contact area with the substrate 10 and improving thermal conductivity. After the paste member 60 is baked, the length LM1 of the exposed surface 48 of the wiring 40 exposed from the resist portion 30 is shorter than the length LM2 of the contact surface 46 in contact with the substrate 10.

[0038] (Polishing or grinding the resist and wiring) In step S14, the resist portion and the wiring are polished or ground, and the wiring 40 protruding from the resist portion 30 is removed. At this time, a portion of the surface of the resist portion 30 may be removed as well. The amount of polishing is preferably 5 μm or less. The amount of grinding is preferably 1 μm to 45 μm, more preferably 5 μm to 25 μm. By polishing the resist portion 30 together, the thickness of the wiring 40 and the resist portion 30 can be adjusted and the insulation between the wirings separated by the resist portion 30 can be stably ensured. The exposed surface 48 of the wiring 40 and the surface of the resist portion 30 are preferably flat and parallel to the surface of the substrate 10. Furthermore, the surface roughness Ra after polishing or grinding is preferably 0.5 μm or less, more preferably 0.1 μm or less. Reducing the surface roughness allows the thickness of the plating film and the organic rust prevention treatment agent to be within a predetermined thickness range, thereby improving the mounting reliability of components mounted on the surface of the wiring 40. The polishing or grinding can be performed using a processing device that uses abrasive grains. In addition to polishing or grinding, cutting or blasting may also be used. After the resist portion 30 and the wiring 40 have been polished or ground, the length LM1 of the exposed surface 48 of the wiring 40 exposed from the resist portion 30 is shorter than the length LM2 of the contact surface 46 that contacts the substrate 10.

[0039] In the method for manufacturing a wiring board, by filling the holes 35 with a paste material 60, the wiring 40 can be formed to conform to the shape of the holes 35. Even when the wiring 40 is made thinner, discontinuities in the pattern are suppressed, and the wiring 40 can be formed with a stable width. Furthermore, by making the resist portion 30 thicker, the wiring 40 can be made thicker, and by making the length LM1 of the exposed surface 48 shorter than the length LM2 of the contact surface 46, peeling of the wiring 40 can be suppressed. In the method for manufacturing a wiring board, by filling holes 35 of a resist portion 30 formed by photolithography with a paste material 60, it is possible to reduce the pattern width and pattern spacing and achieve finer patterning, compared to when applying the paste material 60 by, for example, a printing method. Furthermore, since the wiring 40 is formed of a sintered body 41 of metal particles, it is possible to reduce electrical resistance.

[0040] It is preferable to further cover the exposed portions of the wiring 40, excluding the portions where circuit components and the like are mounted, with an insulating material such as solder resist or a protective film, thereby preventing short circuits between the wirings 40 due to foreign matter and improving migration resistance.

[0041] [Light-emitting device (first embodiment)] Next, the light emitting device 100 according to the first embodiment will be described with reference to FIGS. 6A to 7D. FIG. 6A is a perspective view illustrating the light emitting device 100. FIG. 6B is a plan view illustrating the light emitting device 100. FIG. 6C is a plan view illustrating the wiring substrate 2 of the light emitting device 100. FIG. 6D is a cross-sectional view taken along line VID-VID in FIG. 6B. FIG. 7A is a perspective view illustrating the light source 20. FIG. 7B is a plan view illustrating the light source 20. FIG. 7C is a bottom view illustrating the light source 20. FIG. 7D is a cross-sectional view taken along line VIID-VIID in FIG. 7B.

[0042] The light emitting device 100 includes a wiring board 2 according to the embodiment, and a light source 20 including a light emitting element 22 that is disposed on the wiring board 2. Here, the light emitting device 100 includes a frame member 130 that surrounds the light source 20 at a distance on the wiring board 2, and a sealing member 150 that covers the light source 20, and the light source 20 is disposed in the center of a circular area surrounded by the frame member 130. The light emitting device 100 is, for example, a COB (Chip on Board) type light emitting device in which one light source 20 is arranged on a wiring board 2. Each component of the light emitting device 100 will be described below.

[0043] (wiring board) The wiring board 2 is a ceramic substrate, and the resist portion 30 and the wiring 40 are formed only on the first surface 10A of the base material 10. In other respects, it is the same as the wiring board 1, and the wiring 40 is arranged in the hole 35 of the resist portion 30 so as to contact the base material 10, and in a cross-sectional view in the thickness direction of the base material 10, the length LM1 of the exposed surface 48 of the wiring 40 exposed from the resist portion 30 is shorter than the length of the contact surface 46 in contact with the base material 10. Here, the wiring board 2 is rectangular, and the first surface 10A is the upper surface. The resist portion 30 is preferably white to enhance light reflectivity. To achieve the white color, a white pigment such as titanium oxide, aluminum oxide, calcium carbonate, barium sulfate, magnesium oxide, or silicon oxide may be contained in the base material.

[0044] In plan view, the wiring 40 has a pair of positive and negative rectangular external electrodes 141 and semicircular internal electrodes 142 that are continuous with the external electrodes 141. The external electrodes 141 are provided at opposing corners of the wiring substrate 2. The internal electrodes 142 are provided to surround a circular area A1 in which the light source 20 is disposed. A light source electrode 143 for disposing the light source 20 is provided in the center of the area A1 and is continuous with the internal electrode 142. The light source electrode 143 has four pad portions 44A to 44D. In plan view, the pad portions 44A to 44D each have a square exposed surface 48 and are arranged spaced apart from each other in two rows and two columns. The pad portions 44A and 44B face one of the pair of element electrodes 21, and the pad portions 44C and 44D face the other of the pair of element electrodes 21. Between the pair of element electrodes 21, the lower surface of the light source 20 faces the resist portion 30. Here, the pad portions 44A and 44B, and the pad portions 44C and 44D are connected on the upper surface side of the wiring substrate 2. Hereinafter, the pad portions 44A to 44D may be collectively referred to as the pad portion 44. Furthermore, the surfaces of the pads 44A, 44B, 44C, and 44D exposed from the resist portion 30 are treated with an organic anti-rust treatment or plated with Ni-Pd-Au or Ni-Au to improve the reliability of soldering and Au bump connections.

[0045] (light source) The light source 20 shown in this example has a light-emitting element 22 having a pair of element electrodes 21 and a resin member 23 arranged on the light extraction surface side of the light-emitting element 22, but it is also possible to have only the light-emitting element 22 without placing the resin member 23 on the light-emitting element 22. The light emitting element 22 includes a semiconductor laminate, in which a resin member 23 is disposed on the upper surface side of the semiconductor laminate, and a pair of element electrodes 21 is disposed on the lower surface side. The semiconductor laminate can have any composition 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 22 can be appropriately selected depending on the purpose of use.

[0046] The resin member 23 is made of, for example, a translucent resin material, and may be, for example, an epoxy resin, a silicone resin, or a mixture thereof. The resin member 23 may contain a phosphor, for example, a phosphor that absorbs blue light from the light-emitting element 22 and emits yellow light, thereby allowing the light source 20 to emit white light. The resin member 23 may also contain multiple types of phosphors, for example, a phosphor that absorbs blue light from the light-emitting element 22 and emits green light, and a phosphor that emits red light, thereby allowing the light source 20 to emit white light.

[0047] The resin member 23 may further contain a light-emitting material such as a phosphor or quantum dots. Examples of such phosphors include cerium-activated yttrium aluminum (gallium-doped) garnet, europium-activated nitrogen-containing calcium aluminosilicate (strontium), manganese-activated potassium fluorosilicate, and β-sialon-based phosphors. Specific examples of phosphors include yttrium aluminum garnet-based 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-based phosphors (e.g., Ca 10 (PO4)6Cl2:Eu), SAE-based phosphors (e.g., Sr4Al 14 O 25 :Eu), chlorosilicate phosphors (e.g., Ca8MgSiO 16 Cl2:Eu), silicate-based phosphors (e.g., (Ba,Sr,Ca,Mg)2SiO4:Eu), β-sialon-based phosphors (e.g., (Si,Al)3(O,N)4:Eu) or α-sialon-based phosphors (e.g., Ca(Si,Al) 12 (O,N) 16 oxynitride phosphors such as (La,Y)3Si6N 11 :Ce), BSESN phosphors (for example, (Ba,Sr)2Si5N8:Eu), SLA phosphors (for example, SrLiAl3N4:Eu), CASN phosphors (for example, CaAlSiN3:Eu) or SCASN phosphors (for example, (Sr,Ca)AlSiN3:Eu), nitride phosphors such as KSF phosphors (for example, K2SiF6:Mn), KSAF phosphors (for example, 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. Examples of 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.

[0048] In plan view, the pair of element electrodes 21 are each triangular in shape here, arranged to enclose two pad portions 44, and are connected to the light source electrode 143 via a conductive connection member 70. The conductive connection member 70 can be, for example, bumps of gold, silver, copper, etc., a conductive paste which is a mixture of metal powders such as gold, silver, copper, platinum, aluminum, etc. and a resin binder, solder of tin-silver-copper (SAC) system or tin-bismuth (SnBi) system, etc.

[0049] (Frame member) The frame member 130 is a member that serves as a frame defining the light-emitting region in the light-emitting device 100. Also, the frame member 130 is a member that serves as a frame for arranging the sealing member 150. The frame member 130 is provided so as to surround the light source 20 at a distance. The frame member 130 is formed in a circular shape with a width thicker than the internal electrode 142 and covers the internal electrode 142, surrounding the region A1 where the light source 20 is arranged. The frame member 130 preferably has light reflectivity. In plan view, the frame member 130 may be in a polygonal shape such as an elliptical shape, a square shape, a pentagonal shape, a hexagonal shape, etc., according to the shape of the region A1 where the light source 20 is arranged.

[0050] Also, in cross-sectional view, it is preferable that the frame member 130 flares toward the wiring substrate 2. The frame member 130 is formed such that the height from the upper surface of the wiring substrate 2 is at least higher than the upper surface of the light source 20. The frame member 130 is insulating and light-reflective, and can be made of, for example, a resin or ceramic containing a light-diffusing material. For example, the resin can be silicone resin, epoxy resin, or the like, and the ceramic can be boron nitride, silicon oxide, aluminum oxide, silicon carbide, or the like. The light-diffusing material can be titanium oxide, silicon oxide, or the like.

[0051] (Sealing member) The sealing member 150 is a member that is placed in the light-emitting region of the light-emitting device 100. The upper surface of the sealing member 150 becomes the light-emitting surface of the light-emitting device 100. The sealing member 150 is also a member that covers and protects the light source 20. The sealing member 150 is filled inside the space surrounded by the frame member 130. The height of the sealing member 150 is not particularly limited. For example, the orientation angle can be increased by making the height of the sealing member 150 the same as or higher than the height of the upper end of the frame member 130. It is preferable that the height of the central portion of the sealing member 150 is higher than the peripheral portion, and that the sealing member 150 has a convex shape in cross section. This allows the light emitting device 100 to increase its brightness when viewed from above. On the other hand, by making the height of the sealing member 150 lower than the height of the upper end of the frame member 130, it is possible to cut off light in the lateral direction. The sealing member 150 preferably has insulating and light-transmitting properties and excellent weather resistance and light resistance. The material of the sealing member 150 can be a resin whose base material is, for example, silicone, epoxy, phenol, polycarbonate, acrylic, etc. The sealing member 150 may contain a wavelength conversion material or a light diffusing material as a filler.

[0052] A protection element 180 may be provided between the positive and negative internal electrodes 142. The protection element 180 may be, for example, a Zener diode, a varistor, a resistor, or a capacitor. The light source electrode 143 may have any shape as long as it is included in the element electrode 21 of the light source 20 in a plan view, and may have, for example, a triangular shape similar to the element electrode 21. Instead of the light source 20, the light emitting element 22 may be disposed singly on the wiring substrate 2. The light emitting element 22 may also be disposed on the wiring substrate 2 with the element electrode 21 facing upward. In this case, the element electrode 21 and the internal electrode 142 can be connected by a wire without providing the light source electrode 143. The light emitting device 100 may include a plurality of light sources 20 or light emitting elements 22. The emission peak wavelengths of the plurality of light sources 20 or light emitting elements 22 may be the same or different.

[0053] [Method for manufacturing the light emitting device (first embodiment)] Next, a method for manufacturing the light emitting device 100 according to the first embodiment will be described with reference to FIGS. 8 to 9D. Fig. 8 is a flowchart illustrating a method for manufacturing the light emitting device 100. Fig. 9A is a cross-sectional view illustrating the wiring substrate 2 in the method for manufacturing the light emitting device 100. Fig. 9B is a cross-sectional view illustrating a state in which the light source 20 is arranged. Fig. 9C is a cross-sectional view illustrating a state in which the frame member 130 is formed. Fig. 9D is a cross-sectional view illustrating a state in which the sealing member 150 is arranged.

[0054] The method for manufacturing the light emitting device 100 includes manufacturing a wiring board 2 by the method for manufacturing a wiring board according to the embodiment (S21), and arranging a light source 20 including a light emitting element 22 on the wiring board 2 and electrically connecting the light emitting element 22 to the wiring board 2 by a conductive connecting member 70 (S22). The method further includes forming a frame member 130 (S23) and arranging a sealing member 150 (S24).

[0055] (Manufacturing wiring boards) In manufacturing a wiring board S21, the wiring board 2 is manufactured by the wiring board manufacturing method already described. The material of the base material 10 can be ceramic. The resist portion 30 and the wiring 40 are formed only on the first surface 10A, which is the upper surface of the base material 10. The wiring 40 forms a rectangular external electrode 141, a semicircular internal electrode 142, and a light source electrode 143 so that the positive and negative electrodes are continuous on the upper surface side of the wiring substrate 2. Here, the light source electrode 143 is formed by connecting two of each of four square pad portions 44 on the upper surface side.

[0056] (Electrically connecting the light emitting element and the wiring board with a conductive connecting member) In step S22 of electrically connecting the light emitting element and the wiring board with a conductive connecting member, the light source 20 is placed on the upper surface of the wiring board 2. The element electrodes 21 of the light source 20 are then joined to the pad portions 44 of the light source electrodes 143 via the conductive connecting members 70, electrically connecting the light emitting element 22 and the wiring board 2 with the conductive connecting members 70. As an example, a case will be described in which paste-like solder is used as the conductive connecting members 70. First, the paste-like solder is applied to the pad portions 44 by screen printing or the like. Next, the light source 20 is placed on the wiring board 2 so that the element electrodes 21 face the pad portions 44. At this time, each of the element electrodes 21 is configured to include two pad portions 44 in a plan view. The element electrodes 21 can then be joined to the pad portions 44 by a reflow method.

[0057] (Forming frame members) In forming a frame member S23, a frame member 130 is formed to surround and separate the light source 20. As an example, the frame member 130 can be formed by applying a material for the frame member 130 that has fluidity before hardening or solidification, and then hardening or solidifying the material. The fluid material can be applied in a circular manner along the internal electrode 142 while being discharged from a dispenser nozzle, for example. The material is applied so that after hardening or solidification, the frame member 130 will be wider than the internal electrode 142 and higher than the light source 20. The resin can be a material that hardens when heated or exposed to ultraviolet light, etc. Ceramics can be hardened by heating under pressure to reduce internal voids and improve light reflectance.

[0058] (Placing a sealing member) In disposing a sealing member S24, the sealing member 150 is disposed inside the area surrounded by the frame member 130. The sealing member 150 is disposed by, for example, filling the inside of the frame member 130 with a thermosetting resin in an uncured, fluid state and then curing it. The thermosetting resin may contain a wavelength conversion material or a light diffusing material. The sealing member 150 is disposed so as to cover the upper surface of the wiring board 2, the light source 20, and the inner side surfaces of the frame member 130. It is preferable that the center portion of the sealing member 150 is formed higher than the peripheral edge portion.

[0059] [Light-emitting device (second embodiment)] Next, a light emitting device 200 according to a second embodiment will be described with reference to FIGS. 10A to 10D. Fig. 10A is a plan view illustrating an example of the light emitting device 200. Fig. 10B is a plan view illustrating a portion of the light emitting device 200. Fig. 10C is a plan view illustrating a portion of the wiring substrate 3 of the light emitting device 200, corresponding to Fig. 10B. Fig. 10D is a cross-sectional view taken along line XD-XD in Fig. 10B.

[0060] The light-emitting device 200 includes a wiring substrate 3 according to the embodiment and a light source 20, including a light-emitting element 22, disposed on the wiring substrate 3. The light-emitting element 22 has a pair of element electrodes 21. The light sources 20 are aligned in the row and column directions on one surface of the wiring substrate 3. The light-emitting element 22 has a pair of element electrodes 21. The light sources 20 are arranged on one surface of the wiring substrate 3. The light-emitting element 22 further includes partition grooves 230 that surround the light sources 20 in a predetermined number of sections, and a light-guiding member 220 that guides light from the light sources 20 to the interior surrounded by the partition grooves 230. However, a light-reflective member may be provided in the partition grooves 230. Furthermore, in this example, the wiring 40 is disposed on the other surface of the wiring substrate 3, except for pad portions 44 that individually face the element electrodes 21. The pad portions 44 are provided at the positions of the pad portions 44 and are connected to the remaining wiring 40 through via conductive portions 50 that penetrate the substrate 10 so as to be electrically connected to the wiring. A resist portion 30 is disposed between adjacent pad portions 44. The light emitting device 200 further includes a light-transmitting member 250 having a first light-transmitting portion 251 in contact with the light source 20 and a second light-transmitting portion 252 located above the light source 20 and the first light-transmitting portion 251, and a light adjustment member 260 arranged above the light source 20, the first light-transmitting portion 251, and the second light-transmitting portion 252, and the light-guiding member 220 is arranged above one surface of the wiring board 3 and to the side of the light source 20.

[0061] The light emitting device 200 is a surface light emitting device in which a large number of light sources 20 are aligned in row and column directions on a wiring substrate 3. Each component of the light emitting device 200 will be described below.

[0062] (wiring board) Similar to the wiring board 1, the wiring board 3 has the wiring 40 arranged in the hole 35 of the resist portion 30 so as to contact the base material 10, and in a cross-sectional view in the thickness direction of the base material 10, the length LM1 of the exposed surface 48 of the wiring 40 exposed from the resist portion 30 is shorter than the length of the contact surface 46 in contact with the base material 10. The resist portion 30 and the wiring 40 are formed on the first surface 10A and the second surface 10B of the base material 10, and have via conduction portions 50. The wiring board 3 is, for example, rectangular, and the light source 20 is arranged on the first surface 10A. In the following description, the first surface 10A side is referred to as the upper surface, and the second surface 10B side is referred to as the lower surface.

[0063] The wiring board 3 has external terminals at its ends to which an external power supply or the like is connected. The wiring 40 is routed from the external terminals to the positions of the light sources 20 and has light source electrodes 243 on which each light source 20 is disposed. Here, the light source electrode 243 has four square pad portions 44A, 44B, 44C, and 44D (sometimes collectively referred to as pad portions 44). The wiring 40 is arranged on the lower surface side of the wiring board 3, except for the pad portions 44 that individually face each of the element electrodes 21. The pad portions 44 are connected to the wiring 40 on the lower surface side through via conductive portions 50 provided at the positions of the pad portions 44. A resist portion 30 is arranged between adjacent pad portions 44.

[0064] The pad portions 44A and 44B face one of the pair of element electrodes 21, and the pad portions 44C and 44D face the other. Between the pair of element electrodes 21, the lower surface of the light source 20 faces the resist portion 30. The pad portions 44A and 44B and the pad portions 44C and 44D are connected on the lower surface side of the wiring substrate 3, respectively. An insulating covering member 270 is formed on the lower surface of the wiring board 3. The covering member 270 may be made of a material such as silicone resin or epoxy resin. The covering member 270 can protect the lower surface of the wiring board 3.

[0065] (light source) The light source 20 may be the same as or different from the light source 20 of the light emitting device 100. For example, the light source 20 may be only a light emitting element, or may be a light emitting element on which a resin member containing a phosphor or the like is disposed, or a light emitting element on which only a phosphor or the like is disposed, or a light emitting element on which a reflective member is fixed to its side surface, etc. In the light emitting device 200, the light sources 20 are aligned in the row and column directions.

[0066] (Dividing groove) The partitioning grooves 230 are grooves that partition and surround a predetermined number of light sources 20. Here, the partitioning grooves 230 are provided in a rectangular lattice pattern, and partition and surround each light source 20. The light-emitting device 200 can control brightness and on / off for each partition surrounded by the partitioning grooves 230. A light-reflective material may be filled into the partitioning groove 230. The material of the material filled into the partitioning groove 230 may be, for example, a resin such as acrylic, polycarbonate, silicone, or epoxy, containing a light-diffusing material such as titanium oxide, silicon oxide, or aluminum oxide.

[0067] (light-guiding member) The light guide member 220 is a member that guides light from the light source 20 to the outside. The light guide member 220 is disposed inside the area surrounded by the partitioning groove 230 and to the side of the light source 20. The light guide member 220 is, for example, a light-transmitting plate-like or sheet-like member, and has a through-hole large enough to allow the light source 20 to be disposed at the position of the light source 20. The through-hole is large enough to surround the light source 20 and the light guide member 220 while separating them. Here, the thickness of the light guide member 220 is greater than the height from the upper surface of the wiring substrate 3 to the upper surface of the light source 20. The material of the light-guiding member 220 may be, for example, a thermoplastic resin such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, or polyester, or a light-transmitting material such as glass. In particular, it is preferable to use polycarbonate, which is highly transparent and inexpensive.

[0068] (Translucent member) The light-transmitting member 250 is a light-transmitting member disposed above and to the side of the light source 20. Here, the light-transmitting member 250 has a first light-transmitting portion 251 that contacts the light source 20, and a second light-transmitting portion 252 that is located above the light source 20 and the first light-transmitting portion 251. The first light-transmitting portion 251 is disposed to the side of the light source 20, and is disposed in contact with the side surface of the light source 20 and the inner surface of the light-guiding member 220. The first light-transmitting portion 251 may also be disposed below the light source 20, and is disposed in contact with the lower surface of the light source 20 and the upper surface of the resist portion 30. The first light-transmitting portion 251 is disposed above the light source 20, and is disposed in contact with the upper surface of the light source 20. The material of the first light transmitting portion 251 is not limited as long as it is a transparent resin, but it is preferable to use a thermosetting resin such as an epoxy resin, a silicone resin, or an acrylic resin. The second light-transmitting portion 252 is disposed in contact with the upper surface of the first light-transmitting portion 251 and the upper surface of the light-guiding member 220. The second light-transmitting portion 252 can have a shape and size that encompasses the first light-transmitting portion 251 in plan view, and is circular here. The second light-transmitting portion 252 may be made of the same material as the first light-transmitting portion 251. The light-transmitting member 250 or the first light-transmitting portion 251 may contain one or more types of phosphors. In addition, the first light-transmitting portion 251 may be arranged only on a portion of the upper surface of the light source 20, or may not be arranged on the upper surface of the light source 20, and the second light-transmitting portion 252 may be in contact with a portion or all of the upper surface of the light source 20.

[0069] (Light adjustment material) The light adjustment member 260 is a sheet-like or plate-like member that is located above the light source 20 and reflects a portion of the light from the light source 20. The light adjustment member 260 is disposed above the light source 20, and if the first light-transmitting section 251 and the second light-transmitting section 252 are provided, the light adjustment member 260 is disposed above these sections. The light adjustment member 260 is disposed on the upper surface of the first light-transmitting section 251, but may also be disposed so as to extend to the upper surface of the light-guiding member 220. The light adjustment member 260 is disposed at a position overlapping the light source 20 in a plan view, and is formed in a shape and size that encompasses the light source 20. Here, the light adjustment member 260 is circular, but it may be rectangular or the like. The light transmittance of the light adjusting member 260 is preferably 20% to 60% with respect to the light from the light source 20, and more preferably 30% to 40%. The material of the light adjusting member 260 may be, for example, a resin material containing a light diffusing material, or a metal material. The resin material may be, for example, polyethylene terephthalate resin, silicone resin, epoxy resin, or a mixture of these. The light diffusing material may be, for example, a known material such as titanium oxide, silicon oxide, aluminum oxide, zinc oxide, or glass. The light adjusting member 260 may contain bubbles such as air.

[0070] In the light emitting device 200, the wiring 40 is arranged on the other surface of the wiring substrate 3, leaving only pad portions 44 that individually face each of the element electrodes 21. Then, a resist portion 30 is formed on the surface of the wiring substrate 3 on which the light source 20 is arranged, excluding the pad portions 44. This allows the light emitting device 200 to suppress light absorption by the wiring 40, and also to increase the light reflectance of the resist portion 30 to increase its area, thereby making it possible to effectively utilize the light from the light source 20.

[0071] The partitioning groove 230 may have different widths at its lower end and upper end. The side surface of the light-guiding member 220 in the partitioning groove 230 may or may not be inclined. The partitioning groove 230 may be formed so that a part of the light-guiding member 220 is continuous on the wiring board 3 side. The depth and shape of the partitioning groove 230 can adjust the light guide between adjacent partitions. The partitioning groove 230 may partition and surround a plurality of light sources 20. As an example, the partitioning groove 230 may partition and surround every four light sources 20 in two rows and two columns, or every nine light sources 20 in three rows and three columns.

[0072] [Method for manufacturing light emitting device (second embodiment)] Next, a method for manufacturing the light emitting device 200 according to the second embodiment will be described with reference to FIGS. 11 to 12F. FIG. 11 is a flowchart illustrating a method for manufacturing the light emitting device 200. FIG. 12A is a cross-sectional view illustrating the wiring substrate 3 in the method for manufacturing the light emitting device 200. FIG. 12B is a cross-sectional view illustrating a state in which the light source 20 is arranged. FIG. 12C is a cross-sectional view illustrating a state in which the light guide member 220 is arranged. FIG. 12D is a cross-sectional view illustrating a state in which the first light transmitting portion 251 is arranged. FIG. 12E is a cross-sectional view illustrating a state in which the second light transmitting portion 252 is arranged. FIG. 12F is a cross-sectional view illustrating a state in which the light adjustment member 260 is arranged.

[0073] The method for manufacturing the light emitting device 200 includes manufacturing a wiring board 3 by the method for manufacturing a wiring board according to the embodiment (S31), and arranging light sources 20 including light emitting elements 22 on the wiring board 3 and electrically connecting the light emitting elements 22 to the wiring board 3 by conductive connecting members 70 (S32). In electrically connecting the light emitting elements to the wiring board by the conductive connecting members (S32), the light sources 20 are arranged in rows and columns on one surface of the wiring board 3. The method further includes arranging light guiding members 220 that guide light from the light sources 20 so as to form partition grooves 230 that partition and surround a predetermined number of the light sources 20. Then, in the step S33 of arranging the light-guiding member, the light-guiding member 220 further includes arranging S34 a light-transmitting member 250 that is arranged on the upper side of one surface of the wiring board 3 and to the side of the light source 20, and that becomes a first light-transmitting portion 251 that contacts the light source 20 and a second light-transmitting portion 252 above the light source 20 and the first light-transmitting portion 251, and arranging S35 a light adjustment member 260 above the light source 20, the first light-transmitting portion 251, and the second light-transmitting portion 252.

[0074] (Manufacturing wiring boards) In manufacturing a wiring board S31, the wiring board 3 is manufactured by the method for manufacturing a wiring board already described. The resist portion 30 and the wiring 40 are formed on the first surface 10A and the second surface 10B of the base material 10. The wiring 40 forms a light source electrode 243 at a position where the light source 20 is arranged on the upper surface of the wiring substrate 3. Here, the light source electrode 243 is formed as four square pad portions 44. A resist portion 30 is formed between adjacent pad portions 44. The remaining wiring 40 for the pad portions 44 can be formed on the lower surface side. The pad portions 44 are connected to the wiring 40 on the lower surface side by providing via conductive portions 50 at the positions of the pad portions 44. After polishing or grinding the resist portion 30 and the wiring 40 (S14), an insulating covering member 270 is formed on the lower surface side. The covering member 270 can be formed, for example, by applying a material for the covering member 270 before hardening and then hardening it.

[0075] (Electrically connecting the light emitting element and the wiring board with a conductive connecting member) In step S32 of electrically connecting the light emitting elements and the wiring board with the conductive connecting member, the light sources 20 are arranged on the upper surface of the wiring board 3. The light sources 20 are arranged in rows and columns on the upper surface of the wiring board 3. Then, as in the manufacturing method of the light emitting device 100, the element electrodes 21 of the light sources 20 are joined to the pad portions 44 of the light source electrodes 243 via the conductive connecting members 70, and the light emitting elements 22 and the wiring board 3 are electrically connected by the conductive connecting members 70.

[0076] (Placing a light guide member) In arranging the light guide member S33, the light guide member 220 is arranged on the surface of the wiring board 3 on which the light source 20 is arranged. Here, the light guide member 220 is formed in advance and has a through hole large enough to surround the light source 20 at a distance. The light guide member 220 is arranged so that the light source 20 is located at the center of the through hole. The light guide member 220 can be fixed to the wiring board 3 via, for example, a light-transmitting adhesive. As an example, the light guide member 220 is formed separately for each light source 20. This allows a partition groove 230 to be formed between adjacent light guide members 220.

[0077] (Placing a light-transmitting member) In arranging a light-transmitting member S34, the light-transmitting member 250 is arranged above and to the side of the light source 20. The light-transmitting member 250 has a first light-transmitting portion 251 and a second light-transmitting portion 252. Here, the first light-transmitting portion 251 is arranged so as to contact the upper surface, side surface, and lower surface of the light source 20. The second light-transmitting portion 252 is arranged so as to contact the upper surface of the first light-transmitting portion 251 and the upper surface of the light-guiding member 220. The first light-transmitting portion 251 can be arranged by filling a material having fluidity before hardening between the light source 20 and the light-guiding member 220 on the upper surface of the wiring substrate 3 and hardening the material. Here, the first light-transmitting portion 251 is arranged to a height that covers the upper surface of the light source 20. The second light-transmitting portion 252 can be arranged by applying a material having fluidity before hardening to the upper surface of the first light-transmitting portion 251 and hardening the material. Here, the second light-transmitting portion 252 is arranged so as to contact a part of the upper surface of the light-guiding member 220. The filling or application of the first light-transmitting portion 251 and the second light-transmitting portion 252 can be performed by a method such as potting, spraying, ink-jet printing, printing, etc. The second light-transmitting portion 252 may be a member formed in a sheet or plate shape and disposed on the first light-transmitting portion 251.

[0078] (Placing a light adjustment member) In arranging the light adjustment member S35, the light adjustment member 260 is arranged on the light-transmitting member 250 above the light source 20. The light adjustment member 260 is arranged at a position overlapping the light source 20 and the light-transmitting member 250 in a planar view. Here, the light adjustment member 260 is arranged on the upper surface of the second light-transmitting portion 252 with a shape and size that encompasses the upper surface of the first light-transmitting portion 251 in a planar view. The light adjusting member 260 may be formed by applying and curing the material of the light adjusting member 260 before curing on the second light transmitting portion 252, or by disposing a member formed in a sheet or plate shape. Here, as an example, a silicone resin containing titanium oxide is applied and cured.

[0079] The first light transmitting portion 251 may be cured after the second light transmitting portion 252 is applied, and simultaneously with the curing of the second light transmitting portion 252. Alternatively, the light adjusting member 260 may be applied, and simultaneously with the curing of the light adjusting member 260, the first light transmitting portion 251 and the second light transmitting portion 252 may be cured. [Industrial Applicability]

[0080] The wiring board, the light-emitting device, and the manufacturing methods thereof according to the embodiments of the present disclosure can be used in illumination light sources such as COB-type light-emitting light sources, backlight light sources for liquid crystal displays, various lighting fixtures, indoor or outdoor displays, various display devices for advertisements and destination guidance, and in-vehicle displays, etc.

[0081] The present disclosure includes the following embodiments: (Section 1) an insulating substrate having a first surface and a second surface opposite to the first surface; a resist portion disposed to cover at least a portion of the first surface and the second surface of the substrate and having holes in a predetermined pattern; a wiring that is arranged in the hole of the resist portion so as to be in contact with the base material, In a cross-sectional view in the thickness direction of the base material, the length of the exposed surface of the wiring that is exposed from the resist portion is shorter than the length of the contact surface that is in contact with the base material. (Section 2) Item 2. The wiring board according to item 1, wherein the hole and the wiring are trapezoidal in cross section in the thickness direction of the base material, and the size of the base angle of the trapezoid is 40 degrees or more and 80 degrees or less. (Section 3) 3. The wiring board according to item 1 or 2, wherein the hole and the wiring are in the shape of an isosceles trapezoid in a cross section in the thickness direction of the base material. (Section 4) 4. The wiring board according to any one of items 1 to 3, wherein the resist portion has a thickness of 5 μm to 50 μm. (Section 5) 5. The wiring board according to any one of items 1 to 4, wherein the exposed surface of the wiring and the surface of the resist portion form flat surfaces parallel to the surface of the base material. (Section 6) 6. The wiring board according to any one of items 1 to 5, wherein the wiring is formed of a sintered body of metal particles. (Section 7) 7. The wiring board according to any one of items 1 to 6, wherein the wiring has a volume resistivity of 10 μΩ·cm or less. (Section 8) 8. The wiring board according to any one of items 1 to 7, wherein the resist portion is white. (Section 9) Item 9. The wiring board according to any one of items 1 to 8, wherein the wiring has a plurality of bubbles with a diameter of 5 μm or less. (Section 10) A wiring board according to any one of items 1 to 9, a light source including a light-emitting element disposed on the wiring substrate. (Section 11) The light-emitting element has a pair of element electrodes, the light sources are arranged in rows and columns on one surface of the wiring board, a partition groove that partitions the light sources into a predetermined number of light sources and surrounds them; Item 11. The light emitting device according to item 10, further comprising a light guide member that guides light from the light source to an inside surrounded by the partition groove. (Section 12) the wiring is arranged on the other surface of the wiring substrate, leaving pad portions facing the respective element electrodes; the pad portion is provided at the position of the pad portion and is connected to the remaining wiring through a via conductive portion that is disposed through the base material so as to be electrically connected to the wiring; Item 12. The light emitting device according to item 10 or 11, wherein the resist portion is disposed between the pad portions adjacent to each other. (Section 13) a light-transmitting member having a first light-transmitting portion in contact with the light source and a second light-transmitting portion located above the light source and the first light-transmitting portion; a light adjusting member disposed above the light source, the first light transmitting portion, and the second light transmitting portion, 13. The light emitting device according to any one of items 10 to 12, wherein the light guide member is disposed above one surface of the wiring board and to the side of the light source. (Section 14) preparing an insulating substrate having a first surface and a second surface opposite to the first surface, wherein a resist portion is disposed so as to cover at least one of the first surface and the second surface of the substrate, and a hole portion is formed in the resist portion such that a part of the first surface and the second surface of the substrate are exposed from the resist portion; filling the holes in the resist portion with a paste material containing metal particles; and firing the paste component at a temperature of 150°C or higher and lower than the melting point of the metal particles. In preparing the base material, the hole is formed so that the width of the inner bottom surface of the hole is larger than the width of the opening; A method for manufacturing a wiring board, in which the paste member is fired to sinter the metal particles to form wiring in a shape that conforms to the inner bottom surface and inner side surface of the hole, and the wiring is electrically connected. (Section 15) Item 15. The method for manufacturing a wiring board according to item 14, further comprising polishing or grinding the resist portion and the wiring after firing the paste member. (Section 16) Item 16. The method for manufacturing a wiring board according to item 14 or 15, wherein after the paste member is baked, the length of the exposed surface of the wiring exposed from the resist portion is shorter than the length of the contact surface in contact with the base material. (Section 17) Item 17. The method for manufacturing a wiring board according to item 15 or 16, wherein after polishing or grinding the resist portion and the wiring, the length of the exposed surface of the wiring exposed from the resist portion is shorter than the length of the contact surface that contacts the base material. (Section 18) Item 18. A method for manufacturing a wiring substrate according to any one of items 14 to 17, wherein, in forming the resist portion, the hole portion is formed in a trapezoidal shape with a base angle of 40 degrees or more and 80 degrees or less in a cross-sectional view in the thickness direction of the base material. (Section 19) Item 19. The method for manufacturing a wiring board according to any one of items 14 to 18, wherein the forming of the resist portion comprises forming the hole portion by photolithography. (Section 20) Item 19. The method for manufacturing a wiring board according to any one of items 14 to 19, wherein, in filling the paste material, the metal particles are copper particles having a particle size of 0.1 μm or more and 10 μm or less, and the proportion of particles having a particle size of 0.1 μm or more and 1 μm or less is 40% by weight to 95% by weight. (Section 21) Item 21. The method for manufacturing a wiring substrate according to any one of items 14 to 20, wherein the paste member is fired by heating the paste member to 200°C or higher and 300°C or lower in the atmosphere while being pressurized at 2 MPa or higher and 10 MPa or lower. (Section 22) Item 21. The method for manufacturing a wiring substrate according to any one of items 14 to 20, wherein the paste member is fired by heating the paste member to 200°C or higher and 300°C or lower in a vacuum or a nitrogen atmosphere while being pressurized at 2 MPa or higher and 10 MPa or lower. (Section 23) Item 23. The method for manufacturing a wiring substrate according to any one of items 14 to 22, wherein in filling the paste material, the paste material contains an organic solvent having a boiling point of 200°C or more and 300°C or less and having reducing properties in an amount of 5% to 20% of the weight of the metal particles. (Section 24) Manufacturing a wiring board by the method for manufacturing a wiring board according to any one of items 14 to 23; a light source including a light emitting element disposed on the wiring board, and electrically connecting the light emitting element and the wiring board with a conductive connecting member. (Section 25) The light emitting elements are electrically connected to a wiring board by a conductive connecting member, and the light sources are arranged in rows and columns on one surface of the wiring board; Item 25. A method for manufacturing a light emitting device according to item 24, further comprising forming a light guide member for guiding light from the light sources so as to form partition grooves that partition and surround the light sources in a predetermined number. (Section 26) In forming the light guide member, the light guide member is disposed above one surface of the wiring substrate and to the side of the light source; disposing a translucent member to be a first translucent portion in contact with the light source and a second translucent portion above the light source and the first translucent portion; Item 26. The method for manufacturing a light emitting device according to item 24 or 25, further comprising: arranging a light adjustment member above the light source, the first light transmitting portion, and the second light transmitting portion. [Explanation of symbols]

[0082] 1. Wiring board 2. Wiring board (COB type light emitting device) 3. Wiring board (surface light emitting device) 10 Base material 10A 1st side 10B 2nd side 15 through holes 20 light source 21 Element electrode 22 Light-emitting element 23 Resin parts 30 Resist section 35 Hole 36 Inner bottom surface 37 Inner surface 38 Aperture 40 Wiring 41 Sintered body 42 Bubbles 44 Pad section 46 Contact surface 47 Side 48 Exposed surface 50 Via Conduction 60 Paste material 70 Conductive connecting member 100 Light-emitting device (COB type light-emitting device) 130 Frame members 141 External electrode 142 Internal electrode 143 Light source electrodes (COB type light emitting devices) 150 Sealing member 180 Protection element 200 Light-emitting device (surface light-emitting device) 220 Light guide member 230 Partition Ditch 243 Light source electrodes (surface light emitting devices) 250 Translucent material 251 1st transparent section 252 2nd transparent part 260 Light adjustment material 270 Covering materials

Claims

1. preparing an insulating substrate having a first surface and a second surface opposite to the first surface, wherein a resist portion is disposed so as to cover at least one of the first surface and the second surface of the substrate, and a hole portion is formed in the resist portion such that a portion of the first surface and the second surface of the substrate are exposed from the resist portion; filling the holes in the resist portion with a paste material containing metal particles; and firing the paste member at a temperature of 150°C or higher and lower than the melting point of the metal particles. In preparing the base material, the hole is formed so that the width of the inner bottom surface of the hole is larger than the width of the opening; In filling the paste material, the metal particles are copper particles having a particle size of 0.1 μm or more and 10 μm or less, and the proportion of particles having a particle size of 0.1 μm or more and 1 μm or less is 40% by weight or more and 95% by weight or less, and the paste material is filled so as to bulge from the opening of the hole portion, In firing the paste member, the paste member is heated to 200°C or higher and 300°C or lower in a vacuum or nitrogen atmosphere while being pressurized at 2 MPa or higher and 10 MPa or lower, thereby sintering the metal particles to form wiring from the sintered body of the metal particles in a shape that conforms to the inner bottom surface and inner side surface of the hole, and a manufacturing method for a wiring board in which the wiring is electrically connected.

2. A method for manufacturing a wiring board as described in claim 1, wherein the wiring obtained by firing the paste member has multiple bubbles or voids with a diameter of 5 μm or less.

3. A method for manufacturing a wiring board as described in Claim 2, wherein the air bubbles contained in the wiring obtained by firing the paste member are 1% or more and 20% or less per unit volume.

4. 4. The method for manufacturing a wiring substrate according to claim 1, further comprising polishing or grinding the resist portion and the wiring after firing the paste member.

5. 4. The method for manufacturing a wiring board according to claim 1, wherein after the paste member is fired, the length of the exposed surface of the wiring that is exposed from the resist portion is shorter than the length of the contact surface that is in contact with the base material.

6. 4. A method for manufacturing a wiring board according to claim 1, wherein after polishing or grinding the resist portion and the wiring, the length of the exposed surface of the wiring exposed from the resist portion is shorter than the length of the contact surface in contact with the substrate.

7. 4. A method for manufacturing a wiring board according to claim 1, wherein, in forming the resist portion, the hole portion is formed in a trapezoidal shape having a base angle of 40 degrees or more and 80 degrees or less in a cross-sectional view in the thickness direction of the substrate.

8. The method for manufacturing a wiring substrate according to claim 1 , wherein the forming of the resist portion comprises forming the hole portion by photolithography.

9. manufacturing a wiring board by the method for manufacturing a wiring board according to any one of claims 1 to 3; a light source including a light emitting element disposed on the wiring board, and electrically connecting the light emitting element and the wiring board with a conductive connecting member.

10. The light sources are arranged on one surface of the wiring board in a row direction and a column direction, and the light sources are electrically connected to the wiring board by a conductive connecting member. The method for manufacturing a light emitting device according to claim 9 , further comprising forming a light guide member that guides light from the light sources so that partition grooves are formed that partition and surround the light sources every predetermined number of times.

11. In forming the light guide member, the light guide member is disposed above one surface of the wiring substrate and to the side of the light source; disposing a translucent member to be a first translucent portion in contact with the light source and a second translucent portion above the light source and the first translucent portion; The method for manufacturing a light emitting device according to claim 10 , further comprising: arranging a light adjusting member above the light source, the first light transmitting portion, and the second light transmitting portion.

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