Planar light source and method for manufacturing same

Abstract

The invention provides a planar light source and a manufacturing method thereof, which can inhibit light emitted by the light source from being absorbed by a wiring material. The planar light source is mainly provided with: a light source (20) having a pair of positive and negative electrodes (21) on one surface side; a light guide member (10) that covers the light source (20) such that the electrode (21) is exposed; a wiring substrate (30) having a wiring layer (32) electrically connected to the electrode (21); and a light reflecting sheet (40) interposed between the light guide member (10) and the wiring board (30). The light-reflecting sheet (40) has first through-holes (41) that face a pair of positive and negative electrodes (21) one by one, and the electrodes (21) and the wiring layer (32) are electrically connected by conductive members (50) disposed through the first through-holes (41).

Description

[0001] This application is a divisional application of the invention patent application with the application date of April 8, 2021, the application number of 202110378466.5, and the invention title of "Planar Light Source and Manufacturing Method Thereof". Technical Field

[0002] The present disclosure relates to a planar light source and a manufacturing method thereof. Background Art

[0003] Planar light sources using light-emitting diodes as light sources are used in many devices such as backlights for liquid crystal televisions. In order to achieve high brightness and low power consumption of such planar light sources, it is necessary to effectively utilize the light from the light source. For example, in Patent Document 1, a technique for improving the light extraction efficiency in a light-emitting device in which wirings are exposed and light-emitting elements are connected is disclosed.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-003994 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] The technical problem of the present disclosure is to provide a planar light source and a manufacturing method thereof that suppress absorption of light from the light source by wiring materials.

[0009] Means for Solving the Technical Problem

[0010] The planar light source of the present disclosure includes: a light source having a pair of positive and negative electrodes on one side; a light guide member covering the light source in such a manner that the electrodes are exposed; a wiring substrate having a wiring layer electrically connected to the electrodes; and a light reflecting sheet sandwiched between the light guide member and the wiring substrate, having first through holes respectively opposed to the electrodes in a pair of positive and negative electrodes; the electrodes and the wiring layer are electrically connected by a conductive member disposed through the first through holes.

[0011] The manufacturing method of the planar light source of the present disclosure includes: a light-emitting module preparation step of preparing a light-emitting module including a light source, a light guide member, and a first light reflecting sheet, the light source having a pair of positive and negative electrodes on one side, the light guide member covering the light source in such a manner that the electrodes are exposed, and the first light reflecting sheet having first through holes respectively opposed to the electrodes in a pair of positive and negative electrodes; a wiring substrate preparation step of preparing a wiring substrate having a wiring layer electrically connected to the electrodes; a light-emitting module bonding step of bonding the light-emitting module to the wiring substrate; and a connection step of electrically connecting the electrodes and the wiring layer by a conductive member disposed in the first through holes.

[0012] In addition, the method for manufacturing a planar light source according to the present disclosure includes: a wiring substrate preparation step of disposing a first light reflecting sheet having a first through hole on a wiring substrate having a wiring layer such that the wiring layer faces the first through hole, the wiring layer being electrically connected to the electrodes of a light source having a pair of positive and negative electrodes on one side, and the first through hole facing each of the pair of positive and negative electrodes one by one; a light emitting module preparation step of preparing a light emitting module including the light source, a second light reflecting sheet, and a light guiding member, the second light reflecting sheet having a second through hole that faces the first through hole and in which the light source is disposed, the light guiding member covering the light source in such a manner that the electrodes are exposed, the light source being disposed in the second through hole, and the light source being disposed on the light guiding member; a light emitting module bonding step of sandwiching the first light reflecting sheet such that the electrodes face the first through hole and bonding the light emitting module to the wiring substrate; and a connection step of electrically connecting the electrodes to the wiring layer via a conductive member disposed in the first through hole.

[0013] Advantages of the Invention

[0014] According to the present disclosure, it is possible to realize a planar light source and a method for manufacturing the same that can suppress the absorption of light by wiring materials and can more effectively utilize the light emitted by a light source. Description of the Drawings

[0015] Figure 1 is a schematic perspective view showing a planar light source according to a first embodiment.

[0016] Figure 2 is Figure 1 a schematic sectional view taken along line II-II shown in

[0017] Figure 3A is a schematic perspective view showing an example of a light source according to a first embodiment.

[0018] Figure 3B is Figure 3A a schematic sectional view taken along line IIIB-IIIB shown in

[0019] Figure 3C is showing Figure 3A a schematic bottom view of a surface of the light source having electrodes shown in

[0020] Figure 4 is a schematic top view of an opening of a covering layer in a wiring substrate according to a first embodiment.

[0021] Figure 5 is a schematic perspective view showing a light emitting module according to a first embodiment.

[0022] Figure 6 It is a schematic top view showing the positional relationship between the light source and the light reflecting member of the first embodiment.

[0023] Figure 7A It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0024] Figure 7B It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0025] Figure 7C It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0026] Figure 7D It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0027] Figure 7E It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0028] Figure 7F It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0029] Figure 8A It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0030] Figure 8B It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0031] Figure 9A It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0032] Figure 9B It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0033] Figure 9C It is a schematic cross-sectional view showing an example of the manufacturing method of the first embodiment.

[0034] Figure 10 It is a schematic cross-sectional view showing a part of the planar light source of the second embodiment.

[0035] Figure 11A It is a schematic cross-sectional view showing an example of the manufacturing method of the second embodiment.

[0036] Figure 11B It is a schematic cross-sectional view showing an example of the manufacturing method of the second embodiment.

[0037] Figure 12AIt is a schematic cross-sectional view showing an example of the manufacturing method of the second embodiment.

[0038] Figure 12B It is a schematic cross-sectional view showing an example of the manufacturing method of the second embodiment.

[0039] Figure 13 It is a schematic cross-sectional view showing a part of the planar light source of the third embodiment.

[0040] Figure 14 It is a schematic perspective view showing the light-emitting module of the third embodiment.

[0041] Figure 15A It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0042] Figure 15B It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0043] Figure 15C It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0044] Figure 15D It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0045] Figure 15E It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0046] Figure 15F It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0047] Figure 15G It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0048] Figure 15H It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0049] Figure 16A It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0050] Figure 16B It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0051] Figure 16C It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0052] Figure 17A It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0053] Figure 17B It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0054] Figure 17C It is a schematic cross-sectional view showing an example of the manufacturing method of the third embodiment.

[0055] Figure 18A It is a schematic cross-sectional view showing a modified example of the light source.

[0056] Figure 18B It is a schematic cross-sectional view showing a modified example of the light source.

[0057] Figure 18C It is a schematic cross-sectional view showing a modified example of the light source.

[0058] Figure 18D It is a schematic cross-sectional view showing a modified example of the light source.

[0059] Figure 19A It is a schematic perspective view showing a modified example of the light guide member.

[0060] Figure 19B It is a schematic cross-sectional view showing a modified example of the light guide member.

[0061] Figure 19C It is a schematic cross-sectional view showing a modified example of the light guide member.

[0062] Figure 20A It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0063] Figure 20B It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0064] Figure 20C It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0065] Figure 20D It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0066] Figure 20E It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0067] Figure 20F It is a schematic cross-sectional view showing an example of the manufacturing method of a modified example of the light guide member.

[0068] Figure 21 It is a schematic cross-sectional view showing a planar light source of a wiring board having a modified example of the present embodiment.

[0069] Figure 22 is a flowchart showing a method for manufacturing a planar light source according to this embodiment.

[0070] Explanation of reference numerals

[0071] 10 Light guide member

[0072] 11 Light source arrangement portion of the light guide member

[0073] 15a Light guide plate

[0074] 20 Light source

[0075] 21 Pair of positive and negative electrodes of the light source

[0076] 22 Light emitting element of the light source

[0077] 23 Light transmissive member of the light source

[0078] 24A Light adjustment member of the light source (first light adjustment member)

[0079] 25 Region between electrodes on the surface of the light source having electrodes

[0080] 26 Covering member of the light source

[0081] 30 Wiring substrate

[0082] 31 Third through-hole

[0083] 32 Wiring layer of the wiring substrate

[0084] 34 Insulating substrate of the wiring substrate

[0085] 36 Cover layer of the wiring substrate

[0086] 40 Light reflecting sheet, first light reflecting sheet

[0087] 41 First through-hole

[0088] 45 Second light reflecting sheet

[0089] 46 Second through-hole

[0090] 50 Conductive member

[0091] 51 First conductive member

[0092] 52 Second conductive member

[0093] 60 Light adjustment member (second light adjustment member)

[0094] 70 Light reflecting member

[0095] 75 Deformation Example of Light Reflection Component

[0096] 80 Protection Component

[0097] 90 Bonding Substrate

[0098] 100 Light Emitting Module

[0099] 150 Aggregate of Light Emitting Modules

[0100] 200A Part of Planar Light Source

[0101] 200, 300 Planar Light Sources Detailed Implementation Manner

[0102] Hereinafter, the planar light source and its manufacturing method according to the embodiment will be described with reference to the drawings. Note that the drawings referred to in the following description of the embodiment are used to schematically represent the embodiment. Therefore, there are cases where the dimensions, intervals, or positional relationships of each component are exaggerated, a part of the component illustration is omitted, or an end view showing only the cut surface is used as a sectional view. In addition, in the following description, for the same names and reference numerals, in principle, the same or homogeneous components are indicated, and detailed descriptions are appropriately omitted. In this specification, "upper", "lower", etc. represent the relative positions between the components in the drawings referred to for the purpose of explanation, and unless otherwise specified, they do not intend to represent absolute positions.

[0103] [First Embodiment]

[0104] <Planar Light Source>

[0105] Refer to Figures 1 to 4 An example of the structure of the planar light sources 200 and 300 according to the first embodiment will be described. Figure 2 The planar light source 200 shown in cross-section has a structure corresponding to a part 200A of the planar light source 300. The planar light source 200 and the planar light source 300 are different in the number of light emitting modules described later, and for one light emitting module, they have the same structure.

[0106] The planar light source 300 mainly includes: a light source 20 having a pair of positive and negative electrodes 21 on one side; a light guide member 10 covering the light source 20 in such a manner that the electrodes 21 are exposed; a wiring substrate 30 having a wiring layer 32 electrically connected to the electrodes 21; and a light reflection sheet 40 interposed between the light guide member 10 and the wiring substrate 30. For each of the pair of positive and negative electrodes 21 of the light source 20, the light reflection sheet 40 has a first through-hole 41 facing the electrode 21 one by one, that is, for one electrode 21, the light reflection sheet 40 has one first through-hole 41 facing the electrode 21, and the electrode 21 and the wiring layer 32 are electrically connected by a conductive member 50 disposed through the first through-hole 41.

[0107] Hereinafter, each structure of the planar light source 300 will be described. Note that the light extraction surface of the planar light source 300 is the upper surface of the light guide member 10 on the side opposite to the light reflecting sheet 40. Note that in the present embodiment, a light adjusting member 60 is disposed on the upper surface of the light guide member 10.

[0108] <Light source>

[0109] As Figures 2 to 3C shown, the light source 20 has a pair of positive and negative electrodes 21 on one side, and the light source 20 emits light by being applied with a voltage from the outside via the electrodes 21. As Figures 3A to 3C shown, the light source 20 includes a light emitting element 22, a light transmissive member 23A, and a first light adjusting member 24A. The light source 20 has a shape close to a rectangular parallelepiped, and has a pair of positive and negative electrodes 21 exposed on the lower surface of the light transmissive member 23A on the side opposite to the upper surface where the first light adjusting member 24A is disposed.

[0110] The light emitting element 22 includes a semiconductor stack. In the present embodiment, the light emitting element 22 is at least surrounded by the light transmissive member 23A on the upper surface and the side surfaces of the semiconductor stack. The semiconductor stack is configured to be able to emit visible light or ultraviolet light, and any composition can be used according to the desired emission peak 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, AlInGaP, etc. that can emit red light can be used. In addition, the size, number, etc. of the light emitting element 22 can be appropriately selected according to the use purpose.

[0111] The semiconductor stack includes an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer sandwiched therebetween. The light emitting layer may have a structure such as a double heterojunction or a single quantum well (SQW), or may have a structure including a group of active layers such as a multi quantum well (MQW).

[0112] In addition, the semiconductor laminate may have a structure including one or more light-emitting layers between an n-type semiconductor layer and a p-type semiconductor layer, or may have a structure in which the structure including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer in this order is repeated multiple times. When the semiconductor laminate includes a plurality of light-emitting layers, the light-emitting layers may include light-emitting layers having different peak emission wavelengths or may include light-emitting layers having the same peak emission wavelength. Note that the case where the peak emission wavelengths are the same also includes the case where there is a deviation of about several nm. The combination of the peak emission wavelengths between the plurality of light-emitting layers can be appropriately selected. For example, when the semiconductor laminate includes two light-emitting layers, the light-emitting layers can be selected according to combinations such as blue light and blue light, green light and green light, red light and red light, ultraviolet light and ultraviolet light, blue light and green light, blue light and red light, or green light and red light. Each light-emitting layer may include a plurality of active layers having different peak emission wavelengths or may include a plurality of active layers having the same peak emission wavelength.

[0113] The light-transmissive member 23A is made of, for example, a light-transmissive resin material, and resins such as epoxy resin, silicone resin, or a resin obtained by mixing them can be used. The light-transmissive member 23A may also include a phosphor. For example, by including a phosphor that absorbs blue light from the light-emitting element 22 and emits yellow light, white light can be emitted from the light source 20. In addition, the light-transmissive member 23A may also include a plurality of types of phosphors. For example, by including a phosphor that absorbs blue light from the light-emitting element 22 and emits yellow light and a phosphor that emits red light, white light can also be emitted from the light source 20. As such a phosphor, for example, yttrium / aluminum / garnet-based phosphors (e.g., Y3(Al,Ga)5O 12 :Ce), lutetium / aluminum / garnet-based phosphors (e.g., Lu3(Al,Ga)5O 12 :Ce), terbium / aluminum / garnet-based phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), CCA-based phosphors (e.g., Ca10(PO4)6C 12 :Eu), SAE-based phosphors (e.g., Sr4Al 14 O 25 :Eu), alkaline earth chlorosilicate-based phosphors (e.g., Ca ８ MgSi4O 16 C 12 :Eu), β-sialon-based phosphors (e.g., (Si,Al)3(O,N)4:Eu), α-sialon-based phosphors (e.g., Mz(Si,Al) 12 (O,N) 16: Eu (where 0 < z ≤ 2, and M is Li, Mg, Ca, Y, and lanthanide elements other than La and Ce)), nitride phosphors such as SLA - type phosphors (e.g., SrLiAl₃N₄:Eu), CASN - type phosphors (e.g., CaAlSiN₃:Eu), or SCASN - type phosphors (e.g., (Sr,Ca)AlSiN₃:Eu), fluoride phosphors such as KSF - type phosphors (e.g., K₂SiF₆:Mn), KSAF - type phosphors (e.g., K₂(Si,Al)F₆:Mn), or MGF - type phosphors (e.g., 3.5MgO·0.5MgF₂·GeO₂:Mn), phosphors with a perovskite structure (e.g., CsPb(F,Cl,Br,I)₃), or quantum dot phosphors (e.g., CdSe, InP, AgInS₂, or AgInSe₂), etc.

[0114] In addition, a wavelength - converting sheet containing the above phosphors can be disposed on the planar light sources 200 and 300. The wavelength - converting sheet can absorb a part of the blue light from the light source 20 and emit yellow light, green light, and / or red light to form a planar light source that emits white light. For example, a light source capable of emitting blue light can be combined with a wavelength - converting sheet containing a phosphor capable of emitting yellow light to obtain white light. In addition, a light source capable of emitting blue light can be combined with a wavelength - converting sheet containing red and green phosphors. In addition, a light source capable of emitting blue light can also be combined with multiple wavelength - converting sheets. As the multiple wavelength - converting sheets, for example, a wavelength - converting sheet containing a phosphor capable of emitting red light and a wavelength - converting sheet containing a phosphor capable of emitting green light can be selected. In addition, a light source having a light - emitting element capable of emitting blue light and a light - transmissive member containing a phosphor capable of emitting red light can be combined with a wavelength - converting sheet containing a phosphor capable of emitting green light.

[0115] The first light adjustment member 24A is a member for adjusting the light distribution of the light source 20. The first light adjustment member 24A blocks or reflects a part of the light that passes through the upper surface of the light source 20 and exits from the inside of the light source 20 to the outside. The light distribution of the light source 20 is adjusted via the first light adjustment member 24A so that the light emission directly above the light extraction surface of the planar light source 300 is not too strong and the light emission of the entire surface is uniform. When the transmittance of the light emitted from the light-emitting element 22 through the first light adjustment member 24A is sufficiently low, for example, when it is 1% or more and 50% or less, preferably 3% or more and 30% or less, the first light adjustment member 24A becomes a light-shielding film, and it is possible to avoid excessive brightness directly above the light source 20. As the first light adjustment member 24A, for example, a resin material containing a light-diffusing material can be used, or a metal material can be used. For example, as the resin material, silicone resin, epoxy resin, or a resin obtained by mixing them can be used. In addition, as the light-diffusing material, for example, known materials such as titanium oxide, silicon dioxide, aluminum oxide, zinc oxide, or glass can be used. In addition, the first light adjustment member 24A can be a multilayer film (dielectric multilayer film) composed of a dielectric formed by laminating two or more types of dielectrics.

[0116] <Light guide member>

[0117] As Figure 1 , Figure 2 shown, the light guide member 10 is a light-transmissive member having a function of extracting light from the light source 20 as planar light from the upper surface of the planar light source 300 that serves as the light extraction surface. The lower surface of the light guide member 10 is configured to face the light reflection sheet 40 except for the light source arrangement portion 11 where the light source 20 is arranged. In other words, the light reflection sheet 40 faces the entire lower surface of the light guide member 10 and the entire lower surface of the light source 20 completely, and it is possible to suppress the absorption of light by the wiring layer 32 or the like and effectively utilize the light of the light source 20. The height of the light guide member 10 in the direction perpendicular to the light reflection sheet 40 is equal to or more than the height of the light source 20, and can exceed the height of the light reflection member 70 described later. The height of such a light guide member 10 is preferably set to about 200 μm or more and 800 μm or less, for example.

[0118] The light source 20 is arranged on the lower surface side of the light guide member 10 so that the electrode 21 is exposed. The concave portion of the light guide member 10 where the light source 20 is arranged is the light source arrangement portion 11. The light guide member 10 covers the upper surface and the side surface of the light source 20 arranged in the light source arrangement portion 11.

[0119] As the material of the light guide member 10, for example, resin materials such as thermoplastic resins such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, or polyester, thermosetting resins such as epoxy resin or silicone resin, or light-transmissive materials such as glass can be used. Polycarbonate with high transparency and low cost is particularly preferably used.

[0120] On the upper surface of the light guide member 10, in order to reduce brightness unevenness, for example, convex portions and / or concave portions may be provided in regions with low brightness.

[0121] <Light reflecting sheet>

[0122] The light reflecting sheet 40 is a sheet-like member that reflects light toward the light extraction surface side of the planar light source 300. The light reflecting sheet 40 is disposed between the light guide member 10 and a wiring substrate 30 described later, and has a first through hole 41 that faces one electrode 21 for one electrode 21.

[0123] As long as the opening of the first through hole 41 is sized such that it can include the entire electrode 21 inside when viewed from above, it is easy to electrically connect the electrode 21 and a conductive member 50 described later. However, the larger the opening of the first through hole 41, the smaller the light reflecting sheet 40 at the position opposite to the light source 20. Therefore, the area of the wiring layer 32 and the like irradiated with light from the light source 20 through the first through hole 41 becomes larger. Moreover, irradiating the wiring layer 32 and the like with light increases the chance of light being absorbed. Therefore, it is preferable to reduce the opening of the first through hole 41 such that the shape of the opening of the first through hole 41 is substantially the same as the shape of the electrode 21 or is inside the outer edge of the electrode 21 when viewed from above. In addition, it is preferable that the opening of the first through hole 41 does not protrude outward beyond the outer edge of the light source 20 when viewed from above. In other words, the opening of the first through hole 41 is preferably inside the outer edge of the light source 20 when viewed from above. Thereby, light from the light source 20 being absorbed by the conductive member 5 placed in the first through hole 41 can be reduced.

[0124] In order to effectively utilize light, the light reflecting sheet 40 preferably has a high reflectivity. The reflectivity of the light reflecting sheet 40 is preferably 90% or more, more preferably 94% or more, for example, in the wavelength of the light emitted by the light source 20. [[ID=!6]]

[0125] The light reflecting sheet 40 can be a resin sheet containing a plurality of bubbles (e.g., a foamed resin sheet), a resin sheet containing a light diffusing material, etc. As the resin for these light reflecting sheets 40, for example, thermoplastic resins such as acrylic resin, polycarbonate resin, cyclic olefin resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyester resin, or thermosetting resins such as epoxy resin or silicone resin can be used. In addition, as the light diffusing material, for example, known materials such as titanium oxide, silicon dioxide, aluminum oxide, zinc oxide, or glass can be used.

[0126] <Second light adjusting member>

[0127] The planar light source 300 includes a light adjusting member (second light adjusting member) 60 disposed on the light guide member 10 so as to face the light source 20 with the light guide member 10 interposed therebetween.

[0128] The second light adjustment member 60 is a member for weakening the light directly above the light source 20 on the light extraction surface of the planar light source 300 to make the brightness of the light extraction surface closer to uniform. As the transmittance of such a second light adjustment member 60, it is preferably 20% or more and 60% or less, more preferably 30% or more and 40% or less, relative to the light from the light source 20. In the second light adjustment member 60, similar to the first light adjustment member 24A, a light-reflecting material such as a resin material or a metal material containing a light-diffusing material can be used, for example. The second light adjustment member 60 in the present embodiment covers the entire light source 20 in a plan view, and its outer edge has a circular shape, but it may also have a rectangular shape. In addition, the second light adjustment member 60 is in the form of a film in the present embodiment, but it may also be in the form of dots.

[0129] <Light reflection member>

[0130] The planar light source 300 is provided with a light reflection member 70 at a position away from the light source 20, and the light reflection member 70 surrounds the light source 20 in a rectangular frame shape in a plan view.

[0131] The light reflection member 70 is a member that reflects the light from the light source 20 toward the light extraction surface side of the planar light source 300 and extracts it. The light reflection member 70 has a predetermined height, and the light reflection member 70 is arranged along the outer periphery of the light guide member 10 above the light reflection sheet 40. The light reflection member 70 divides the light guide member 10 for each light source 20, thereby being able to suppress the light guiding between adjacent sections. Thereby, local dimming can be performed to control the light-emitting area in units of sections.

[0132] The height of the light reflection member 70 in the direction perpendicular to the light reflection sheet 40 is preferably equal to or more than the height of the light source 20. In a plan view, the length of one side of the rectangular frame-shaped light reflection member 70 is larger than the length of one side of the light source 20, for example, in the range of 5 times to 30 times.

[0133] The inner side surface of the light reflection member 70 is convexly curved toward the light source 20 side in the present embodiment, but it may also be concavely curved. In particular, the cross-sectional shape of the light reflection member 70 is preferably such that the width becomes narrower as it is farther from the light reflection sheet 40 in the height direction. Thereby, the light from the light source 20 can be efficiently extracted toward the light extraction surface side of the planar light source 300. The inner side surface of the light reflection member 70 can be a single plane, a single curved surface, a combination of planes with different inclinations with respect to the light reflection sheet 40, a combination of multiple curved surfaces with different curvatures, or a combination of a plane and a curved surface.

[0134] The reflectance of the light reflecting member 70 for the light from the light source 20 is preferably 60% or more, more preferably 90% or more, for example. The light reflecting member 70 can use, for example, a resin containing a light diffusing material. As the resin for the light reflecting member 70, thermoplastic resins such as acrylic resin, polycarbonate resin, cyclic olefin resin, polyethylene terephthalate resin or polyester resin, or thermosetting resins such as epoxy resin or silicone resin can be used. In addition, as the light diffusing material, known materials such as titanium oxide, silicon dioxide, aluminum oxide, zinc oxide or glass can be used.

[0135] <Wiring substrate>

[0136] The wiring substrate 30 includes an insulating substrate 34, a wiring layer 32 disposed on the insulating substrate 34 and electrically connected to a pair of positive and negative electrodes 21, and a covering layer 36 covering the wiring layer 32. Moreover, the wiring substrate 30 has a third through hole 31 that communicates with and penetrates the wiring layer 32 respectively with the first through hole 41.

[0137] The wiring substrate 30 can use, for example, a rigid substrate or a flexible substrate.

[0138] Note that the wiring substrate 30 has a first surface on the side where the light source 20 is not disposed, and a second surface on the opposite side of the first surface.

[0139] The wiring layer 32 is a path member for applying a voltage to the light source 20. For example, as Figure 4 shown, the shape of the wiring layer 32 in the portion where the third through hole 31 is disposed can be wider than other linear wiring layers.

[0140] The wiring layer 32 can use a metal material. For example, single metals such as Ag, Al, Ni, Rh, Au, Cu, Ti, Pt, Pd, Mo, Cr, W, alloys containing these metals, or conductive pastes containing metal powders thereof can be appropriately used. As the shape of the metal powder, for example, spherical, flaky or needle-like shapes can be used.

[0141] The wiring layer 32 is disposed on the insulating substrate 34.

[0142] The material of the insulating substrate 34 is, for example, an insulating resin material such as phenolic resin, epoxy resin, polyimide resin, BT resin, polyphthalamide. The insulating substrate 34 can also use ceramic materials such as alumina and aluminum nitride. In addition, the insulating substrate 34 can also have a structure in which insulating members are arranged in layers on the surface of a metal member.

[0143] The covering layer 36 is a member for protecting the wiring layer 32. The covering layer 36 can be configured to cover the entire insulating substrate 34. In the first embodiment, for example, as Figure 4As shown, the cover layer 36 has an opening 37 in such a manner that the third through-hole 31 and the wiring layer 32 disposed around it are exposed. As the material of the cover layer 36, an insulating material can be used, for example, polyimide.

[0144] <Conductive component>

[0145] The conductive component 50 is a component that electrically connects the electrode 21 and the wiring layer 32.

[0146] As described above, on the light reflecting sheet 40, the first through-holes 41 are arranged in a one-to-one correspondence with the respective electrodes 21 of the light source 20 that are in a positive-negative pair. On the wiring substrate 30, the third through-holes 31 are arranged in communication with the first through-holes 41 respectively. That is, between the electrode 21 and the wiring layer 32, there is a path from the electrode 21 to the wiring layer 32 in which one electrode 21 corresponds to one third through-hole 31 in a one-to-one manner. The conductive components 50 are respectively arranged in this path to electrically connect the electrode 21 and the wiring layer 32.

[0147] As the material of the conductive component 50, in addition to the same material as the wiring layer 32, for example, known materials such as tin-silver-copper (SAC) type and tin-bismuth (SnBi) type solders can be used.

[0148] In the planar light source 300, the electrical contacts of the wiring layer 32 and the conductive component 50 are arranged inside the third through-hole 31 and on the surface of the wiring layer 32 on the side opposite to the surface of the light reflecting sheet 40 side. Here, the surface of the wiring layer 32 on the side opposite to the surface of the light reflecting sheet 40 side is the first surface of the wiring substrate 30. On the first surface side of the wiring substrate 30, for example, as Figure 4 shown, in a plan view, the third through-hole 31 is arranged at a position overlapping the wiring layer 32. In other words, the third through-hole 31 is arranged at a position inside the outer edge of the wiring layer 32. The contacts of the wiring layer 32 and the conductive component 50 are arranged at the exposed part of the wiring layer 32 on the inner side surface of the third through-hole 31 (the inner side surface of the through-hole of the wiring layer 32) and the wiring layer 32 around the third through-hole 31, and reliable electrical connection can be achieved. In addition, in the present embodiment, the inner side surface of the third through-hole 31 is arranged in such a manner that the inner side surface of the through-hole of the wiring layer 32 and the inner side surface of the through-hole of the insulating substrate 34 become the same surface, but it can also be arranged in such a manner that the inner side surface of the through-hole of the wiring layer 32 is outside the inner side surface of the through-hole of the insulating substrate 34. That is, in a plan view, the width of the through-hole of the wiring layer 32 can also be larger than the width of the through-hole of the insulating substrate 34. In addition, the wiring layer 32 can be arranged to surround the entire periphery of the through-hole of the insulating substrate 34 as in the present embodiment in a plan view, but it can also be arranged at a part of the periphery of the through-hole of the insulating substrate 34.

[0149] <Protecting component>

[0150] In addition to the above structure, the planar light source 300 may also include a protection component 80 that covers the opening 37 of the covering layer 36 of the wiring substrate 30. The protection component 80 is an insulating component that protects the wiring layer 32 and the conductive component 50 from short - circuiting.

[0151] The protection component 80 can be made of phenyl silicone resin, dimethyl silicone resin, epoxy resin, acrylic resin, polyurethane resin, etc. In addition, the protection component 80 can have light - transmissivity. For example, pigments such as titanium oxide can be added to make it light - impermeable. In particular, by making the protection component 80 have light - transmissivity, the connection state between the wiring layer 32 and the conductive component 50 can be visually confirmed, which is thus more preferable.

[0152] According to the planar light source 300 having the structure described above, the conductive component 50 is connected to the electrode 21 via the first through - holes 41 disposed on the light - reflecting sheet 40 in a one - to - one correspondence with the positive and negative pair of electrodes 21 of the light source 20. Therefore, in the planar light source 300, the entire lower surface of the light source 20 except for the electrodes 21 faces the light - reflecting sheet 40, and the light of the light source 20 can be effectively utilized. In addition, since the positive and negative pair of electrodes 21 are separately disposed, regardless of the shape and arrangement of the electrodes 21, as Figure 3C shown, there is a region 25 between the positive and negative pair of electrodes 21 of the light source 20 on the lower surface of the light source 20. This region 25 also faces the light - reflecting sheet 40, so the light of the light source 20 can be utilized more effectively. In this way, the planar light source 300 can increase the area of the light - reflecting sheet 40 facing the light source 20 and can reduce the area of the wiring layer 32, etc., irradiated by light. Thus, the planar light source 300 can suppress the absorption of light by the wiring layer 32, etc., and can effectively utilize the light of the light source 20.

[0153] Note that the light source 20 disposed on the wiring substrate 30 can be one or more. The number of light sources 20 can be appropriately selected according to the size and shape of the planar light source 300. In addition, the interval between the light sources 20 can be appropriately adjusted.

[0154] <Manufacturing method of the planar light source of the first embodiment>

[0155] Next, for the manufacturing method of the planar light source 300 of the first embodiment, an example will be described with reference to Figures 1 to 9C 、 Figure 22 as follows.

[0156] The manufacturing method of the planar light source 300 includes: a light-emitting module preparation step S1 of preparing a light-emitting module 100, which includes a light source 20, a light guide member 10, and a first light reflecting sheet 40. The light source 20 has a pair of positive and negative electrodes 21 on one side. The light guide member 10 covers the light source 20 in such a way that the electrodes 21 are exposed. The first light reflecting sheet 40 has first through holes 41 that respectively face the positive and negative electrodes 21 of the light source 20 one by one; a wiring board preparation step S2 of preparing a wiring board 30, which has a wiring layer 32 electrically connected to the electrodes 21; a light-emitting module bonding step S3 of bonding the light-emitting module 100 to the wiring board 30; and a connection step S4 of electrically connecting the electrodes 21 to the wiring layer 32 via a conductive member 50 disposed in the first through holes 41. Note that here, either the light-emitting module preparation step S1 or the wiring board preparation step S2 can be carried out first, or they can also be carried out simultaneously.

[0157] <Light-emitting module preparation step>

[0158] The light-emitting module preparation step S1 is a step of preparing a light-emitting module 100 that includes at least a light source 20, a light guide member 10, and a first light reflecting sheet 40. Note that in the manufacturing method of the planar light source 300, by combining Figure 5 the light-emitting module 100 shown or a unit formed by arranging a plurality of light-emitting modules 100 with the wiring board 30, it is constituted. Note that the light-emitting module 100 in the present embodiment further includes a light reflecting member 70 and a light adjusting member (second light adjusting member) 60.

[0159] In addition, here, a case where after forming an aggregate of light-emitting modules 100, the aggregate is singulated to form a plurality of light-emitting modules 100 will be described. Here, singulation includes not only the case of cutting into a unit having one light source 20, but also the case of cutting into a unit having two or more light sources 20. And the singulated light-emitting modules can be respectively bonded to the wiring board 30 in the subsequent light-emitting module bonding step.

[0160] First, as Figure 7A shown, the first through holes 41 are provided on the light reflecting sheet in such a way that one first through hole 41 corresponds to one electrode 21 of the light source 20, and the first light reflecting sheet 40 is formed. That is, in this example, two first through holes 41 are provided for one light source 20. The formation of the first through holes 41 can be carried out, for example, by punching using a punch having a shape substantially consistent with the shape of the electrode 21 when viewed from above. Note that the formation of the first through holes 41 can be carried out, for example, by using a drill or a laser in addition to punching. Alternatively, a light reflecting sheet having the first through holes 41 can be purchased.

[0161] Next, as Figure 7BAs shown, the light source 20 is disposed in alignment on the first light reflecting sheet 40 such that the first through hole 41 faces the electrode 21. The region 25 between the positive and negative pair of electrodes 21 on the surface of the light source 20 having the electrode 21 faces the first light reflecting sheet 40.

[0162] Next, as Figure 7C shown, the light reflecting member 70A is disposed so as to surround the light source 20 at a certain distance. As Figure 6 shown, the light reflecting member 70A forms a grid pattern in a plan view. Each grid of the light reflecting member 70A surrounds one light source 20 at the center. The light reflecting member 70A can be formed, for example, by coating the material of the light reflecting member 70A in a state having appropriate adhesiveness on the first light reflecting sheet 40. As an example, the cross section of the light reflecting member 70A may be a shape obtained by cutting an ellipse in half along the minor axis, but may also be a triangular shape, or may be a rectangular shape, for example.

[0163] Next, as Figure 7D shown, the light guiding member 10 is disposed so as to cover the light source 20. For example, the light guiding member 10 can be disposed by injecting and curing a resin which is the material of the light guiding member 10 into the region surrounded by the frame formed by the light reflecting member 70A. Note that the injection of the resin can be performed from the nozzle of a dispenser, or can be coated by screen printing or spraying, or these methods can be used simultaneously. In this manufacturing method, as a result, the position where the light source 20 is pre-disposed becomes the light source disposing portion 11 in the light guiding member 10. Since the lower surface of the light source 20 is not covered by the light guiding member 10, the electrode 21 faces the first through hole 41 of the first light reflecting sheet 40 in a state of being exposed from the light guiding member 10. The entire lower surface of the light source 20 except for the electrode 21 faces the first light reflecting sheet 40, and the light from the light source 20 can be effectively utilized. Note that the light guiding member 10 can also be prepared by injection molding or transfer molding, or can be prepared by purchasing a formed component.

[0164] Next, as Figure 7E shown, the light adjusting member 60 is disposed on the light guiding member 10 so as to face the light source 20 with the light guiding member 10 interposed therebetween. For example, the light adjusting member 60 can be formed by coating a resin which is the material of the light adjusting member 60 on the light guiding member 10 and curing it. At this stage, the aggregate 150 of the light emitting modules 100 before being made into a single piece is formed.

[0165] Then, as Figure 7F shown, the aggregate 150 of the light emitting modules 100 is cut at the grid lines 70B of the light reflecting member 70A to be made into a single piece. The cutting can be performed, for example, by a known method using a cutting blade or a laser. In this way, a plurality of light emitting modules 100 can be formed.

[0166] <Wiring Substrate Preparation Process>

[0167] The wiring substrate preparation process S2 is a process of preparing the wiring substrate 30 for bonding the light-emitting module 100. Here, third through-holes 31 that are respectively communicated with the first through-holes 41 and penetrate the wiring layer 32 are formed in the wiring substrate 30. Figure 8A A cross-sectional view of the wiring substrate 30A before the formation of the third through-holes 31 is shown. Figure 8B A cross-sectional view of the wiring substrate 30 after the formation of the third through-holes 31 is shown.

[0168] First, the wiring layer 32A is disposed on the insulating substrate 34A, and the covering layer 36 is disposed so as to cover the wiring layer 32A, thereby forming the wiring substrate 30A. Regarding the covering layer 36, in order to dispose the conductive member 50 in the subsequent process, as Figure 4 shown, as an example, an opening 37 is formed in advance in such a manner that the place where the third through-hole 31 is to be formed and its surroundings are exposed.

[0169] Next, on the wiring substrate 30A before the formation of the third through-holes 31, the third through-holes 31 are formed in such a manner that they are respectively communicated with the first through-holes 41 of the first light-reflecting sheet 40 and penetrate the wiring layer 32. The third through-holes 31 can be formed, for example, by processing based on punching, a drill, or a laser. Note that the wiring substrate preparation process S2 may also be to form the wiring layer and the covering layer as described above and prepare by incorporating a wiring substrate having the third through-holes 31.

[0170] <Light-Emitting Module Bonding Process>

[0171] The light-emitting module bonding process S3 is a process of bonding the wiring substrate 30 and the light-emitting module 100.

[0172] As Figure 9A shown, an adhesive resin is coated on the surface of the wiring substrate 30 to which the light-emitting module 100 is to be bonded, and alignment is performed in such a manner that the first through-holes 41 and the third through-holes 31 are opposed to each other, thereby bonding the light-emitting module 100. The illustration of the adhesive resin is omitted. As the adhesive resin, for example, a known resin containing an acrylic resin, an epoxy resin, or a polyurethane resin can be used. Note that in Figure 9A , adjacent light-emitting modules 100 are in close contact. However, the interval between the light-emitting modules 100 can also be set to about 1% to 10% of the width of the light-emitting module 100, for example, and can be appropriately set.

[0173] Regarding the wiring substrate 30 to which the light-emitting module 100 is bonded, when viewed from the side of the surface where the light-emitting module 100 is not bonded, the third through-hole 31 communicates with the first through-hole 41 of the first light-reflecting sheet 40, and the front end of the first through-hole 41 is blocked by the electrode 21 of the light source 20. That is, holes are formed in the number of electrodes 21, with the electrode 21 as the bottom and the third through-hole 31 as the entrance.

[0174] <Connection process>

[0175] The connection process S4 is a process of electrically connecting the electrode 21 and the wiring layer 32 using the conductive member 50. Figure 9B The cross-sectional view at the end of the connection process S4 is shown.

[0176] First, the conductive member 50 is injected into the hole with the third through-hole 31 as the entrance. When injecting the conductive member 50, the wiring substrate 30 to which the light-emitting module 100 is bonded is placed horizontally with the light-emitting module 100 side facing down. The conductive member 50 needs to be able to reach the electrode 21 at the bottom of the hole while ensuring an amount of contact with the wiring layer 32 inside the third through-hole 31. The conductive member 50 is injected in an amount that further spreads on the surface of the wiring layer 32 outside the third through-hole 31. That is, the electrical connection contact between the conductive member 50 and the wiring layer 32 is also provided on the surface of the wiring layer 32 on the side opposite to the surface of the first light-reflecting sheet 40, making the electrical connection between the conductive member 50 and the wiring layer 32 more reliable.

[0177] After injecting the conductive member 50, a process of heating the conductive member 50 (such as the reflow method) is performed. Note that the conductive member 50 can be provided separately for each hole as in this embodiment, or can be provided in a way that makes the adjacent holes continuous, and separated for each hole using a laser or the like before or after heating the conductive member 50. In addition, the conductive member 50 can be injected from the nozzle of a dispenser, can be provided by screen printing, or can use both nozzle injection and screen printing, for example, screen printing is performed after nozzle injection.

[0178] <Protection member forming process>

[0179] In addition to the above-described processes, a protection member forming process S5 can be further performed. The protection member forming process S5 is a process of forming a protection member 80 that covers the conductive member 50 and the exposed wiring layer 32. As Figure 9C shown, in the protection member forming process S5, the protection member 80 is formed in such a way that the covering layer 36 located around the opening 37 is also covered.

[0180] As described above, by separately preparing the light-emitting module 100 and the wiring substrate 30, each process can be performed simultaneously or independently, so that the manufacturing process can be made more efficient. Since this manufacturing method bonds the light-emitting module 100 or a unit formed by arranging a plurality of light-emitting modules 100 to the wiring substrate 30, it is easy to adjust the interval and the number of the light-emitting modules 100.

[0181] [Second Embodiment]

[0182] Regarding the structure of the planar light source of the second embodiment, taking it as a planar light source 201 having one light-emitting module, refer to Figure 10 and explain it.

[0183] The planar light source 201 is different from the planar light source 200 of the first embodiment in terms of the structure of the conductive member. The other structures are the same as those of the first embodiment. Note that for the parts that are the same as those of the first embodiment, the description will be appropriately omitted.

[0184] <First Conductive Member and Second Conductive Member>

[0185] The conductive member of the planar light source 201 includes a first conductive member 51 disposed in the first through hole 41 and a second conductive member 52 disposed between the first conductive member 51 and the wiring layer 32. Moreover, the electrode 21 and the wiring layer 32 are electrically connected via the first conductive member 51 and the second conductive member 52.

[0186] Note that the first conductive member 51 can be disposed in the first through hole 41 so as to be flush with the surface of the light reflection sheet 40, can be disposed lower than the surface of the light reflection sheet 40, or can be disposed to protrude from the first through hole 41. As the materials of the first conductive member 51 and the second conductive member 52, the same materials as those of the conductive member 50 described in the first embodiment can be used. The materials of the first conductive member 51 and the second conductive member 52 can be the same or different.

[0187] Regarding the planar light source 201, the entire lower surface of the light source 20 except for the electrode 21 faces the light reflection sheet 40, and the light from the light source 20 can be effectively utilized. The shape of the first conductive member 51 on the light source 20 side can be adjusted to match the shape of the electrode 21. In addition, the first conductive member 51 can select a material suitable for bonding with the electrode 21.

[0188] <Manufacturing Method of Planar Light Source of Second Embodiment>

[0189] Regarding the manufacturing method of the planar light source of the second embodiment, refer to Figures 11A to 12B 、 Figure 22An example thereof will be described. Note that the accompanying drawings show an example in which a plurality of light-emitting modules are combined with a wiring substrate.

[0190] The light-emitting module preparation step S12 and the connection step S42 in the manufacturing method of the planar light source according to the second embodiment are different from those of the manufacturing method of the planar light source according to the first embodiment described above. Other than this, it is the same as the manufacturing method of the first embodiment.

[0191] <Connection step>

[0192] In the connection step S42 in the manufacturing method of the planar light source according to the second embodiment, the electrode 21 is electrically connected to the wiring layer 32 via a conductive member passing through the first through-hole 41 provided in the first light-reflecting sheet 40 in advance. Note that the conductive member provided in the first through-hole 41 in advance is the first conductive member 51, and the conductive member disposed between the first conductive member 51 and the wiring layer 32 is the second conductive member 52.

[0193] The step of providing the first conductive member 51 is performed in the light-emitting module preparation step S12. As Figure 11A 、 Figure 11B shown, the first conductive member 51 is disposed in the first through-hole 41 of the first light-reflecting sheet 40 before the light source 20 is disposed. Note that the first conductive member 51 and the electrode 21 of the light source 20 are joined using solder or the like. As Figure 12A 、 Figure 12B shown, the step of providing the second conductive member 52 is performed after the light-emitting module 101 is bonded to the wiring substrate 30. Note that the light-emitting module preparation step S12 is the same as the light-emitting module preparation step S1 in the first embodiment except for providing the first conductive member 51.

[0194] In the manufacturing method of the second embodiment, a conductive member is provided in the first through-hole 41 in advance, and the other steps can be performed in the same manner as in the first embodiment. Therefore, this manufacturing method can form the planar light source of the second embodiment while exhibiting the advantages of the manufacturing method of the first embodiment.

[0195] [Third Embodiment]

[0196] Regarding an example of the structure of the planar light source according to the third embodiment, let it be a planar light source 202 having one light-emitting module, and reference Figure 13 is made to explain it.

[0197] The structure of the light-reflecting sheet of the planar light source 202 is different from that of the planar light source 200 according to the first embodiment. Other than this, the structure is the same as that of the first embodiment. In addition, for the parts that are the same as those in the first embodiment, the description will be appropriately omitted.

[0198] <First light-reflecting sheet and second light-reflecting sheet>

[0199] The light reflecting sheet of the planar light source 202 includes a first light reflecting sheet 40 having a first through hole 41 and a second light reflecting sheet 45 having a second through hole 46 that faces the first through hole 41 and in which the light source 20 is disposed.

[0200] The planar light source 202 is the same as the planar light source 200 of the first embodiment. The entire lower surface of the light source 20 except for the electrodes 21 faces the first light reflecting sheet 40, and the light of the light source 20 can be effectively utilized. Moreover, the planar light source 202 can reduce the area of the irradiated light of the wiring layer 32 or the like by making the region 25 between the electrodes 21 of the light source 20 face the first light reflecting sheet 40. In addition, the planar light source 202 is configured such that the first light reflecting sheet 40 and the second light reflecting sheet 45 overlap around the light source 20. By arranging the light reflecting sheets in an overlapping manner, the planar light source 202 can further reduce the irradiation of light to the wiring layer 32 or the like.

[0201] <Manufacturing Method of Planar Light Source of Third Embodiment>

[0202] Regarding the manufacturing method of the planar light source of the third embodiment, refer to Figures 14 to 17C 、 Figure 22 An example thereof will be described. Note that the drawings show an example in which a plurality of light emitting modules are combined with a wiring substrate.

[0203] The manufacturing method of the planar light source of the third embodiment includes: a wiring substrate preparation step S2A of disposing the first light reflecting sheet 40 having the first through hole 41 on the wiring substrate 30 having the wiring layer 32 such that the wiring layer 32 faces the first through hole 41, electrically connecting the wiring layer 32 to the electrodes 21 of the light source 20 having a pair of positive and negative electrodes 21 on one side, and making the first through hole 41 face each of the pair of positive and negative electrodes 21 of the light source 20 one by one; a light emitting module preparation step S1A of preparing a light emitting module 102 including the light source 20, the second light reflecting sheet 45, and the light guiding member 10, the second light reflecting sheet 45 having a second through hole 46 that faces the first through hole 41 and in which the light source 20 is disposed, the light guiding member 10 covering the light source 20 such that the electrodes 21 are exposed, disposing the light source 20 in the second through hole 46, and disposing the light source 20 in the light guiding member 10; a light emitting module bonding step S3A of sandwiching the first light reflecting sheet 40 such that the electrodes 21 face the first through hole 41 and bonding the light emitting module 102 to the wiring substrate 30; and a connection step S4 of electrically connecting the electrodes 21 to the wiring layer 32 via the conductive member 50 disposed in the first through hole 41. Note that here, either the light emitting module preparation step S1A or the wiring substrate preparation step S2A can be performed first, or they can be performed simultaneously.

[0204] <Light Emitting Module Preparation Step>

[0205] The light-emitting module preparation process S1A is a process of preparing a light-emitting module 102 that at least includes a light source 20, a light guide member 10, and a second light reflection sheet 45. Note that in the process of the manufacturing method, the planar light source 202 is formed by combining the unit formed by arranging the light-emitting module 102 shown below or a plurality of light-emitting modules 102 with the first light reflection sheet 40 and the wiring substrate 30. Moreover, the light-emitting module 102 in the present embodiment further includes a light reflection member 70 and a light adjustment member (second light adjustment member) 60. Figure 14 Note that here, a case where a plurality of light-emitting modules 102 are formed by slicing the aggregate of the light-emitting modules 102 after the aggregate of the light-emitting modules 102 is formed will be described. Similarly here, the slicing includes not only the case of slicing into a unit having one light source 20 but also the case of slicing into a unit having two or more light sources 20. And the sliced light-emitting modules can be bonded to the wiring substrate 30 respectively in the light-emitting module bonding process described later.

[0206] Note that here, a case where a plurality of light-emitting modules 102 are formed by slicing the aggregate of the light-emitting modules 102 after the aggregate of the light-emitting modules 102 is formed will be described. Similarly here, the slicing includes not only the case of slicing into a unit having one light source 20 but also the case of slicing into a unit having two or more light sources 20. And the sliced light-emitting modules can be bonded to the wiring substrate 30 respectively in the light-emitting module bonding process described later.

[0207] First, as Figure 15A shown, a second through hole 46 for arranging the light source 20 is formed in the second light reflection sheet 45. For example, the second through hole 46 can be formed by punching using a punch having a shape similar to the shape of the light source 20 when viewed from above. Note that in addition to punching, for example, the second through hole 46 can also be formed by using a drill or a laser, etc. It is also possible to purchase a light reflection sheet having the second through hole 46.

[0208] Next, as Figure 15B and Figure 15C shown, the second light reflection sheet 45 is overlapped and fixed, and then the support plate P will be removed later, and the light source 20 is arranged in the second through hole 46.

[0209] Next, similar to the first embodiment, as Figures 15D to 15G shown, the light reflection member 70A, the light guide member 10, and the light adjustment member 60 are formed. Then, the support plate P is removed. At this stage, the aggregate 152 of the light-emitting modules 102 before slicing is formed.

[0210] Similar to the first embodiment, as a result, the position where the light source 20 is arranged becomes the light source arrangement portion 11 in the light guide member 10. In addition, since the lower surface of the light source 20 is not covered by the light guide member 10, the electrode 21 is exposed from the light guide member 10.

[0211] Then, similar to the first embodiment, as Figure 15H shown, the aggregate 152 of the light-emitting modules 102 is cut at the grid line 70B of the light reflection member 70A to be sliced into individual pieces.

[0212] <Wiring Substrate Preparation Process>

[0213] The wiring board preparation step S2A is a step of preparing the first light reflection sheet 40 and the wiring board 30 for bonding the light emitting module 102. The first through holes 41 of the first light reflection sheet 40 are arranged such that one first through hole 41 faces one electrode 21 of the light source 20. The first light reflection sheet 40 is disposed on the wiring board 30 at a position where the wiring layer 32 faces the first through holes 41. Further, here, third through holes 31 that communicate with the first through holes 41 respectively and penetrate the wiring layer 32 are formed in the wiring board 30.

[0214] In the wiring board preparation step S2A, it is preferable to simultaneously form the first through holes 41 of the first light reflection sheet 40 and the third through holes 31 of the wiring board 30. That is, preferably, on the bonding substrate 90A formed by bonding the surface on the side where the light emitting module 102 is to be bonded of the first light reflection sheet 40A before forming the first through holes 41 and the wiring board 30A before forming the third through holes 31, through holes facing the electrodes 21 are formed one by one corresponding to the positive and negative pair of electrodes 21 of the light source 20, so that the formation of the first through holes 41 and the formation of the third through holes 31 are continuously performed.

[0215] First, similar to the first embodiment, as Figure 16A shown, the wiring board 30A before forming the third through holes 31 is formed. Next, as Figure 16B shown, the bonding substrate 90A is formed by bonding the first light reflection sheet 40A before forming the first through holes 41 to the surface on the side where the light emitting module 102 is to be bonded of the wiring board 30A. Then, as Figure 16C shown, on the bonding substrate 90A, for one electrode 21, a through hole facing the electrode 21 of the light source 20 is formed. Thus, by simultaneously forming the first through holes 41 and the third through holes 31, the alignment accuracy between the first light reflection sheet 40 and the wiring board 30 can be improved.

[0216] <Light emitting module bonding step>

[0217] The light emitting module bonding step S3A is a step of bonding the wiring board 30 and the light emitting module 102.

[0218] In the light emitting module bonding step S3A of the third embodiment, the first light reflection sheet 40 is interposed such that the electrodes 21 face the first through holes 41, and the light emitting module 102 is bonded to the wiring board 30. An adhesive resin is coated on the first light reflection sheet 40, as Figure 17AAlignment is performed so that the electrode 21 faces the first through-hole 41, and the light-emitting module 102 is bonded. The bonding resin is omitted from the illustration. Note that if a sheet material having adhesiveness such as an adhesive sheet is used as the first light-reflecting sheet 40, the coating of the bonding resin can be omitted.

[0219] Regarding the wiring substrate 30 after bonding the light-emitting module 102, when viewed from the surface on the side where the light-emitting module 102 is not bonded, the third through-hole 31 communicates with the first through-hole 41 of the first light-reflecting sheet 40, and the front end of the first through-hole 41 is blocked by the electrode 21 of the light source 20. That is, holes are formed with the number of electrodes 21 as the bottom and the third through-hole 31 as the entrance. The region 25 between the positive and negative pair of electrodes 21 on the surface of the light source 20 having the electrode 21 faces the first light-reflecting sheet 40.

[0220] <Connection process and protective member forming process>

[0221] As Figure 17B shown, the connection process S4 is performed in the same manner as in the first embodiment. In addition, the protective member forming process S5 is then performed, so that as Figure 17C shown, for example, the protective member 80 can be formed so as to cover the conductive member 50 and the exposed wiring layer 32, and further cover the covering layer 36 located around the opening 37.

[0222] <Modification example of light source>

[0223] Note that the light source is not limited to the structure of the light source 20 shown. For example, a light source having a positive and negative pair of electrodes 21 on one side surface and emitting blue or white light can be used. Here, a modification example of the light source 20 is described with reference to Figures 18A to 18D as follows.

[0224] As Figure 18A shown, the light source 20A includes a light-emitting element 22 that emits blue light and a light-transmissive member 23A. The light-transmissive member 23A contains a phosphor that emits yellow light, and can make the emission color of the light source 20A white. In addition, the light source 20A has a first light adjustment member 24A on the upper surface and a light reflection layer 24B on the lower surface, which is the surface having the electrode 21. By providing the light reflection layer 24B on the surface having the electrode 21, the light source 20A can reduce the light reaching the wiring layer 32.

[0225] As Figure 18B shown, the light source 20B includes a light-emitting element 22 that emits blue light and a light-transmissive member 23A, and can make the emission color white. In addition, the light source 20B has a first light adjustment member 24A on the upper surface.

[0226] The light-transmitting member 23A of the light source 20B is disposed above the light-emitting element 22. The side surface, the lower surface of the semiconductor laminate of the light-emitting element 22, and the lower surface of the light-transmitting member 23A are respectively covered by the covering member 26. The covering member 26 is a member that covers the light-emitting element 22 to protect it and reflects the light from the light-emitting element 22 toward the light-transmitting member 23A side. Examples of the material for the covering member 26 include silicone resin, epoxy resin, acrylic resin, etc. The covering member 26 contains a light diffusion material such as titanium oxide, barium titanate, aluminum oxide, silicon oxide, etc., for example.

[0227] The light-transmitting member 23A of the light sources 20A and 20B may also be a light-transmitting member 23B that does not contain a phosphor. In addition, the light-transmitting members 23A and 23B may contain a light diffusion material. Examples of the material for the light diffusion material include titanium oxide, barium titanate, aluminum oxide, silicon oxide, etc.

[0228] Note that the light sources 20A and 20B may also have a structure in which a light reflection layer 24B is provided on the lower surface side of the light-emitting element 22 and the first light adjustment member 24A is not provided, or may have a structure in which the first light adjustment member 24A and the light reflection layer 24B are not provided.

[0229] In addition, as Figure 18C , Figure 18D shown, as a modification example of the light source 20, light sources 20C and 20D in which the light-emitting element 22 is not sealed by the light-transmitting member 23A and the covering member 26 can also be used. A first light adjustment member 24C is disposed on the upper surface of the light-emitting element 22 in the light source 20C. In addition, a light reflection layer 24D is further disposed on the surface of the light source 20C having the electrode 21 in the light source 20D.

[0230] Note that, as the material for the first light adjustment members 24A and 24C, similar to the first embodiment, for example, a resin material or a metal material containing a light diffusion material can be used. In addition, as the first light adjustment members 24A and 24C, a dielectric multilayer film can be used, or a film formed by laminating a dielectric multilayer film and a metal film can also be used.

[0231] <Modification example of the method for forming the light guide member>

[0232] In addition, in the manufacturing method of the first embodiment, the light guide member 10 is formed by curing a liquid resin, but a pre-formed light guide member (hereinafter referred to as a light guide plate) can also be used. Note that the liquid state mentioned here also includes a paste state. In addition, although it is described here as a modification example of the first embodiment, it can also be applied to other embodiments in the same way.

[0233] As Figure 19AAs shown, the light guide plate 15a has a concave light source arrangement portion 11 on its lower surface that surrounds the light source 20 in size, and the light guide plate 15a covers the light source 20 in such a manner that the electrode 21 is exposed. The light source 20 is arranged in the light source arrangement portion 11 via a light-transmissive adhesive.

[0234] In addition, as Figure 19B shown, the light source arrangement portion 11 can be a through-hole. After arranging the light source 20 in the through-hole of the light guide plate 15a1, a liquid resin can be injected and cured in such a manner as to cover the upper surface of the light source 20 to form a light guide member 15b. In this example, the light guide member composed of the light guide plate 15a1 and the light guide member 15b covers the light source 20 in such a manner that the electrode 21 is exposed. Note that the resin material of the light guide plate 15a1 and the resin material of the light guide member 15b can be the same or different. In addition, the light guide plate 15a1 can be single-layer or multi-layer. For example, in the case where the light guide plate 15a1 is composed of multiple layers, the layers can be bonded together using an adhesive sheet. As the material of such an adhesive sheet, any material that is light-transmissive to the light emitted from the light source 20 can be used, and in order to reduce the occurrence of interfaces between layers, it is preferable to use the same material as the light guide plate 15a1.

[0235] In addition, as Figure 19C shown, a light guide member 15c including a first light guide plate 15c1 and a second light guide plate 15c2 can also be used. The first light guide plate 15c1 has a through-hole for arranging the light source 20. The thickness of the first light guide plate 15c1 is substantially the same as the thickness of the light source 20. Moreover, the second light guide plate 15c2 is arranged over the upper surface of the light source 20 and the upper surface of the first light guide plate 15c1. In this example, the concave portion formed by combining the first light guide plate 15c1 and the second light guide plate 15c2 is the light source arrangement portion 11, and the light guide member 15c covers the light source 20 in such a manner that the electrode 21 is exposed. Note that the resin material of the first light guide plate 15c1 and the resin material of the second light guide plate 15c2 can be the same or different.

[0236] In the case of using a light guide plate, as Figure 20C and Figure 20D shown, after arranging the light guide plate 15a1 on the first light reflection sheet 40, a light reflection member 75A is arranged. In this case, a part of the light emitting module preparation process is changed. As an example, refer to Figures 20A to 20F to describe the light emitting module preparation process S1B in the case of using the light guide plate 15a1.

[0237] Similar to the light emitting module preparation process S1 in the first embodiment, on the first light reflection sheet 40 having the first through-hole 41, the light source 20 is arranged in alignment such that the first through-hole 41 faces the electrode 21.

[0238] Next, the light guide plates 15a1 are arranged adjacent to each other on the first light reflecting sheet 40 in such a manner that the light source 20 is housed in the light source arrangement section 11. Then, a resin, which is a material for the light guiding member 15b, is injected into the light source arrangement section 11 in the through-hole and cured so as to cover the light source 20. The light guiding member composed of the light guide plates 15a1 and the light guiding member 15b covers the light source 20 in such a manner that the electrode 21 is exposed.

[0239] Next, a material for the light reflecting member 75A is injected into the gaps between the adjacent light guide plates 15a1 and cured. Then, in the same manner as in the first embodiment, a light adjusting member (second light adjusting member) 60 is arranged on the light guide plates 15a1 and the light guiding member 15b. Then, the aggregate 155 of the light emitting modules 105 is cut at the grid lines 75B of the light reflecting member 75A to be made into individual pieces. Note that although the second light adjusting member 60 in the present embodiment covers the entire upper surface of the light guiding member 15b, a part of the upper surface of the light guiding member 15b may be exposed from the second light adjusting member 60.

[0240] Thus, in the case where the light reflecting member 75A is formed by a method of coating or injecting a resin into the gaps between the light guiding members and curing it, the light reflecting member 75A is formed along the shape of the outer side surface of the light guiding member. Therefore, by pre-adjusting the shape of the outer side surface of the light guiding member, the shape of the inner side surface of the light reflecting member 75 can be adjusted.

[0241] In addition, as another modification of the first embodiment, air may be used as the light guiding member.

[0242] <Modification Example of Wiring Substrate>

[0243] Next, a modification example of the wiring substrate will be described with reference to Figure 21 In this modification example, the wiring substrate 30B does not have the third through-hole 31. Therefore, it is configured as follows. The electrical connection contacts of the conductive member 50 and the wiring layer 32 are provided at portions of the surface of the wiring layer 32 on the light reflecting sheet 40 side that are respectively opposed to the first through-holes 41.

[0244] The insulating substrate 34B has openings respectively opposite to the first through-holes 41 of the light reflecting sheet 40, exposing the wiring layer 32B. The portions of the wiring layer 32B respectively opposite to the first through-holes 41 are thicker than other portions in the thickness direction of the wiring substrate 30B. Additionally, in this modified example, the surface of the wiring layer 32B and the surface of the insulating substrate 34B are substantially in the same plane. A conductive member 50 is disposed via the first through-holes 41 between the wiring layer 32B and the electrode 21. Note that the portion of the wiring layer 32B respectively opposite to the first through-holes 41 may protrude from the surface of the insulating substrate 34B or may be lower than the surface of the insulating substrate 34B. The difference in the thickness of the wiring layer 32B can be adjusted according to the thickness of the conductive member 50.

[0245] Additionally, in the method for manufacturing a planar light source based on the wiring substrate 30B that does not have the third through-hole 31, for example, in the light emitting module bonding process, before bonding the light emitting module, the conductive member 50 is disposed on the wiring layer 32B. That is, the conductive member 50 is pre-disposed on the upper surface of the wiring layer 32B, and the light emitting module is bonded. At this time, the conductive member 50 is connected to the electrode 21 of the light source 20 via the first through-hole 41. Additionally, the contact points of the conductive member 50 and the wiring layer 32B are disposed on the portions of the surface of the wiring layer 32B on the side of the first light reflecting sheet 40 respectively opposite to the first through-holes 41.

[0246] The wiring substrate 30B does not need to form an opening 37 in the cover layer 36B. Therefore, there is no need to dispose a protection member 80 that covers the opening 37 of the cover layer 36, and the number of processes in the manufacturing method can be reduced.

[0247] The modified example of the wiring substrate can also be applied to the first embodiment and other embodiments. For example, the conductive member 50 can also be pre-disposed in the first through-hole 41 of the light emitting module 101 as in the light emitting module 101 of the second embodiment. In this case, the conductive member 50 is joined to the electrode 21 of the light source 20 and the wiring layer 32B using solder or the like. Note that the wiring layer can also be multi-layered rather than single-layered. The embodiment of the wiring substrate having the third through-hole 31 and the modified example without the third through-hole 31 can also be similarly implemented when the wiring layer is multi-layered.

Claims

1. A planar light source, characterized in that, Comprising: A light source having a pair of positive and negative electrodes on one side; A light guide member covering the light source in such a manner that the electrodes are exposed; An insulating substrate; A wiring layer which is a wiring layer electrically connected to the electrodes and is disposed on the insulating substrate; A light reflecting member interposed between the light guide member and the insulating substrate and having first through holes respectively opposed to the electrodes which are in a pair of positive and negative; The electrodes and the wiring layer are electrically connected by a conductive member disposed through the first through holes.

2. The planar light source according to claim 1, wherein: The light reflecting member is a first light reflecting member, The planar light source further has a second light reflecting member which has second through holes opposed to the first through holes and in which the light source is disposed.

3. The planar light source according to claim 1 or 2, wherein: The contact points of the conductive member and the wiring layer are disposed at portions respectively opposed to the first through holes on the surface of the wiring layer on the side of the light reflecting sheet.

4. The planar light source according to claim 1 or 2, wherein: The wiring substrate has third through holes respectively communicating with the first through holes and penetrating the wiring layer, and the contact points of the conductive member and the wiring layer are disposed at least inside the third through holes.

5. The planar light source according to claim 4, wherein: The contact points of the conductive member and the wiring layer are further disposed on the surface of the wiring layer opposite to the surface on the side of the light reflecting sheet.

6. The planar light source according to any one of claims 1 to 5, wherein: The conductive member includes a first conductive member disposed in the first through holes and a second conductive member disposed between the first conductive member and the wiring layer.

7. The planar light source according to any one of claims 1 to 6, wherein: The planar light source further includes a light adjusting member disposed on the light guide member in such a manner as to face the light source with the light guide member interposed therebetween.

8. The planar light source according to any one of claims 1 to 7, wherein: The planar light source further includes a light reflecting member surrounding the light source.

9. The planar light source according to any one of claims 1 to 8, wherein: The region between the pair of positive and negative electrodes on the surface of the light source having the electrodes faces the light reflecting sheet.

10. The planar light source according to any one of claims 1 to 9, wherein: A plurality of the light sources are disposed on the wiring substrate.

11. The planar light source according to claim 10, wherein: It has a light reflecting member that divides the light guide member for each of the light sources.

12. The planar light source according to any one of claims 1 to 11, wherein: The wiring layer disposed on the insulating substrate is covered by a covering layer.

013. The planar light source according to any one of claims 1 to 12, wherein: In a top view, the opening of the first through hole is inside the outer edge of the light source.

14. The planar light source according to any one of claims 1 to 12, wherein: In a top view, the shape of the opening of the first through hole is substantially the same as the shape of the electrode, or is closer to the inside than the outer edge of the electrode.

15. The planar light source according to any one of claims 1 to 14, characterized in that the upper surface of the light guide member has a convex portion or a concave portion.

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