JP7244771B2 - Manufacturing method of planar light source - Google Patents

Description

The present invention relates to a planar light source and its manufacturing method.

2. Description of the Related Art Light-emitting devices using light-emitting elements such as light-emitting diodes are widely used as various light sources such as backlights for liquid crystal displays and displays. As such a light-emitting device, a structure in which a light-emitting element is mounted on a substrate having wiring has been proposed. For example, Patent Literature 1 discloses a light-emitting device having wiring on the upper surface of a substrate and connecting an electrode on the lower surface of a light-emitting element to the wiring.

JP 2006-100444 A

In such a light-emitting device in which a large number of light-emitting elements are arranged in a plane, the luminance at the positions where the light-emitting elements are provided may be locally high when viewed from the front. For this reason, there has been a demand for a planar light source whose luminance is nearly constant regardless of location.

An object of the present invention is to provide a planar light source with little luminance unevenness and a method for manufacturing the same.

According to the method for manufacturing a planar light source according to one aspect of the present invention, a composite substrate including a supporting member and a wiring layer provided on the supporting member; a plurality of light emitting elements spaced apart from each other; and a step of arranging covering members separately from each other; a step of arranging a light shielding member so as to fill a space between the covering members; a step of removing the covering members to form a plurality of holes ; After the step of removing the member to form the plurality of holes, the plurality of second covering members are separated from each other so as to continuously cover a portion of the upper surface of the light shielding member from the plurality of holes. arranging a second light shielding member so as to fill the space between the second covering members; and removing the second covering member to form a plurality of steps at the opening end of the hole. and disposing a light-transmitting member in the plurality of holes, wherein the step of disposing the light-transmitting member includes the steps of the hole and the light shielding member arranging the translucent member so as to fill the upper surface .

Further, according to a planar light source according to another aspect of the present invention, a composite substrate including a support member and a wiring layer disposed on the support member; A plurality of light-shielding members, a plurality of light-emitting elements arranged in wiring layers in the plurality of holes of the light-shielding member, and a translucent member arranged in the holes and on the light-shielding member. can be done.

According to the method for manufacturing a planar light source according to one aspect of the present invention, it is possible to obtain a compact planar light source having a plurality of light emitting elements arranged in each hole and partitioned by a light shielding member. Further, according to the planar light source according to another aspect of the present invention, the light emitted from the plurality of light emitting elements partitioned by the light shielding member is partially propagated between adjacent light emitting regions via the translucent member. As a result, it is possible to obtain a planar light source that is close to planar light emission with reduced luminance unevenness.

1 is a schematic plan view showing a planar light source according to Embodiment 1. FIG. It is a schematic plan view which shows the planar light source which concerns on a modification. 2 is an enlarged schematic cross-sectional view of a main part of the planar light source of FIG. 1; FIG. 4 is an SEM photograph showing a hole portion of a planar light source according to an example. 3 is a perspective view showing a mounting area and an extension area of a wiring layer; FIG. FIG. 10 is an enlarged schematic cross-sectional view of a main part showing a planar light source according to Embodiment 2; FIG. 11 is an enlarged schematic cross-sectional view of a main part of a planar light source according to Embodiment 3; It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic diagram which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows the manufacturing process of a planar light source. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. It is a schematic cross section which shows an example of the process of forming a light-shielding member. FIG. 11 is an enlarged schematic cross-sectional view of a main part of a planar light source according to Embodiment 4; FIG. 11 is an enlarged schematic cross-sectional view of a main part of a planar light source according to Embodiment 5; FIG. 11 is an enlarged schematic cross-sectional view of a main part of a planar light source according to Embodiment 6; FIG. 39 is a cross-sectional view of the prism sheet of FIG. 38; FIG. 40 is a plan view with a partially enlarged view of the prism sheet of FIG. 39; FIG. 40 is a bottom view with a partially enlarged view of the prism sheet of FIG. 39; 42 is an enlarged perspective view showing prisms of the prism sheet of FIG. 41; FIG.

The present invention will now be described in detail with reference to the drawings. In the following description, terms indicating specific directions and positions (e.g., "upper", "lower", and other terms including those terms) are used as necessary, but the use of these terms is These terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the invention is not limited by the meaning of these terms. Also, parts with the same reference numerals appearing in a plurality of drawings indicate the same or equivalent parts or members.

Further, the embodiments shown below are examples of methods for manufacturing a planar light source for embodying the technical idea of the present invention, and the present invention is not limited to the following. In addition, unless there is a specific description, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are not intended to limit the scope of the present invention, but are intended to be examples. It is intended. In addition, the contents described in one embodiment and example can also be applied to other embodiments and examples. Also, the sizes and positional relationships of members shown in the drawings may be exaggerated for clarity of explanation.
(Surface light source 100)
[Embodiment 1]

FIG. 1 shows a schematic plan view of a planar light source 100 according to Embodiment 1 of the present invention. A planar light source 100 shown in this figure has a plurality of light emitting elements 20 arranged in a matrix on a rectangular composite substrate 50 . Note that the number of light emitting elements and the arrangement pattern are not limited to this example. For example, instead of arranging the light emitting elements at equal intervals, the intervals between the light emitting elements may be changed depending on the location. For example, as shown in FIG. 2, the intervals between the light emitting elements 20 may be narrowed so that the corners of the rectangular composite substrate 50 are densely spaced while keeping constant intervals in the central portion. In a configuration in which a large number of light-emitting elements are arranged, the corners are relatively darker than the center. It is possible to obtain the planar light source 100 with little luminance unevenness. Further, the light emitting elements may be arranged two-dimensionally, or they may be arranged at positions shifted from a fixed interval for each row. Alternatively, any arrangement pattern such as linear, radial, spiral, etc. can be used as appropriate. The number of light emitting elements to be arranged, the number of rows and columns, and the like are set according to the required specifications, such as the size and density of the planar light source, and the amount of light.

FIG. 3 shows an enlarged schematic cross-sectional view of a main part of such a planar light source 100. As shown in FIG. A planar light source 100 shown in this figure includes a composite substrate 50 , a light shielding member 54 , a light emitting element 20 , and a translucent member 60 . A composite substrate 50 includes a support member 51 and a wiring layer 40 arranged on the support member 51 . The light shielding member 54 is arranged on the composite substrate 50 and has a plurality of holes 56 . The hole portion 56 is a portion defined by the inner side surface of the light shielding member 54 and the upper surface of the composite substrate 50 . The bottom surface of the hole 56 is defined by the top surface of the support member 51 and the top surface of the wiring layer 40 . The light emitting element 20 is connected to the wiring layer 40 in each hole 56 . The details of each member will be described below.
(Light emitting element 20)

The light emitting elements 20 are arranged on the wiring layer 40 inside the plurality of holes 56 of the light shielding member 54 . The light emitting element 20 has an electrode forming surface 20a having positive and negative element electrodes 21, and a light extraction surface 20b opposite to the electrode forming surface 20a. The light emitting element 20 is arranged directly or through a bonding member such as a bump so that the element electrode 21 faces the upper surface of the wiring layer 40 .

A semiconductor light emitting device can be used for the light emitting device 20 . In this embodiment, a light-emitting diode is exemplified as the light-emitting element 20 . The light emitting element 20 emits blue light, for example. An element that emits light other than blue light can also be used as the light emitting element 20 . Further, light emitting elements that emit light of different colors can be used as the plurality of light emitting elements 20 . At least a part of the light emitted from the light emitting element 20 can be adjusted in the emission color emitted to the outside by using the wavelength conversion member 70 . Moreover, when the wavelength conversion member 70 is not included in the planar light source 100 , the blue light from the light emitting element can be emitted as the light from the planar light source 100 .

For example, the light emitting element 20 uses a nitride semiconductor ( _{InxAlyGa1 -xyN} , 0≤X, 0≤Y, X+Y≤1) or GaP as an element that emits blue and green _light . A light-emitting element can be used. A light-emitting element containing a semiconductor such as GaAlAs or AlInGaP can be used as the element that emits red light. Furthermore, semiconductor light-emitting elements made of materials other than these can also be used. The emission wavelength can be varied by changing the material of the semiconductor layer and its degree of alloying. The composition, emission color, size, number, and the like of the light-emitting elements to be used may be appropriately selected according to the purpose.

A plurality of such light emitting elements 20 are arranged two-dimensionally in a plurality of rows and columns on the upper surface of the support member 51 .
(Support member 51)

Composite substrate 50 includes support member 51 and wiring layer 40 . The support member 51 supports the light emitting element 20 on this upper surface. The supporting member 51 can preferably be made of a light reflecting resin 51b. The light reflecting resin 51b is preferably a thermosetting resin having excellent heat resistance and light resistance. For example, a silicone resin, an epoxy resin, or the like can be suitably used. For example, it is possible to use silicone resin mixed with 60% TiO ₂ , which is a light-reflecting filler. The thickness of the support member 51 is, for example, 15 μm to 300 μm.
(wiring layer 40)

The wiring layer 40 is provided on the support member 51 and electrically connects the plurality of light emitting elements 20 . In the example of FIG. 3, the wiring layer 40 is configured by laminating a first metal layer 41 and a second metal layer 42 . An example of the first metal layer 41 is a laminated structure of Al/Ti/Cu from the support member 51 side. As the second metal layer 42, for example, Cu is used. The thickness of the first metal layer 41 is set to 0.1 μm to 1 μm. The thickness of the second metal layer 42 is set to 1 μm to 50 μm. The wiring layer 40 can further laminate a third metal layer and a fourth metal layer.

The wiring layer 40 is exposed inside the hole 56 of the light shielding member 54 . In other words, the wiring layer 40 exposed on the bottom surface of the hole 56 is surrounded by the light shielding member 54 . Further, the light emitting element 20 is arranged on the wiring layer 40 exposed on the bottom surface of the hole portion 56 . An example of the hole portion 56 in which the light emitting element 20 is mounted in the planar light source 100 according to the example is shown in the SEM photograph of FIG.

Also, the width of the wiring layer 40 can be made smaller than its thickness. FIG. 5 shows a mounting area 45 in which the element electrode 21 of the light emitting element 20 is mounted in the wiring layer 40 and an extension area 46 extending from the mounting area 45 . In the figure, the support member 51 is omitted. As shown in this figure, by making the extension region 46 of the wiring layer 40 thicker than the width in the extension direction, the electrical resistance can be reduced and the electrical conductivity can be increased, and the hole portion 56 It is possible to secure a large area occupied by the support member 51 in the region exposed from the light emitting element on the bottom surface of the .

Furthermore, the wiring layer 40 can have a terminal portion 43 electrically connected to the outside in a portion where the light emitting element 20 is not mounted. The terminal portion 43 is connected to an external member such as a power supply circuit via a flexible substrate 44, for example. The flexible substrate 44 can be bonded using, for example, an adhesive layer 62 such as solder paste.
(Reinforcing substrate 52)

Composite substrate 50 may also include a reinforcing substrate. The reinforcing substrate is arranged on the back side of the supporting member 51 and supports the supporting member 51 . If the support member 51 becomes thin, it may warp or wrinkle. On the other hand, there is a strong demand for thin planar light sources, and liquid crystal displays, in particular, are required to have a thickness of 300 μm or less. Therefore, the supporting member 51 alone does not support the light emitting element 20, but the reinforcing substrate 52 is additionally provided to suppress such warpage and reinforce the light emitting element 20. FIG. Therefore, the reinforcing substrate 52 functions as a reinforcing layer. Thereby, the reinforcing substrate 52 can be used to reinforce the composite substrate 50, and the support member 51 can be used to reflect light. The thickness of the reinforcing substrate 52 is set to 25 μm to 200 μm. If the reinforcing substrate 52 is an insulating substrate, it is easy to handle, so it can be suitably used. As the reinforcing substrate 52, for example, CS3305A manufactured by Risho Kogyo Co., Ltd., BN substrate (trade name) manufactured by Printec Co., Ltd., which is polyimide-impregnated glass cloth, etc., are preferably used because they are less likely to warp or wrinkle. can be done. If a light-reflective member is used as the reinforcing substrate 52, the support member 51 can be omitted.
(Light shielding member 54)

The light shielding member 54 is arranged on the composite substrate 50 and has a plurality of holes 56 . The light blocking member 54 is made of a material that blocks the light emitted by the light emitting element 20 . For example, a light-reflecting material or a light-absorbing material can be used. It can preferably be composed of the light reflecting resin 51b. The light reflecting resin 51b is preferably a thermosetting resin having excellent heat resistance and light resistance. For example, a silicone resin, an epoxy resin, or the like can be suitably used. A black resin can be used as a material that absorbs light. Even black-colored resin can exhibit light-shielding performance. Also, the light shielding member 54 can be made of the same material as the support member 51 . As a result, when the light shielding member 54 is arranged on the composite substrate 50, good connection between the resins can be achieved.

By setting the thickness of the light shielding member 54 to 10 μm to 450 μm, the light extraction efficiency can be enhanced.

The shape of the hole 56 of the light shielding member 54 can be a cylinder, a polygonal prism such as a quadrangular prism or a hexagonal prism, a truncated cone, a truncated polygonal pyramid, or the like.
(translucent member 60)

The translucent member 60 is arranged inside the hole 56 and on the light shielding member 54 . In this way, the light emitted from the light emitting element 20 in a plurality of light emitting regions partitioned by the light shielding member 54 is partially propagated between adjacent light emitting regions through the translucent member 60, thereby reducing luminance unevenness. It is possible to obtain a planar light source with

The translucent member 60 is a member that optically couples the wavelength conversion member 70 with the light emitting element 20 . The translucent member 60 has translucency, and fixes the wavelength conversion member 70 and the light emitting element 20 in an optically coupled state. For such a translucent member 60, a translucent resin such as an epoxy resin, a silicone resin, a mixed resin of these, glass, or the like can be used.
(Wavelength conversion member 70)

A wavelength conversion member 70 is arranged on the translucent member 60 and the light shielding member 54 . The wavelength converting member 70 contains a wavelength converting substance that converts the light emitted by the light emitting element 20 into light of different wavelengths. As the wavelength conversion member 70, a sheet formed by dispersing a wavelength conversion substance in a base material can be used. A phosphor is mentioned as a wavelength conversion substance. Examples thereof include YAG phosphors, β-sialon phosphors, and fluoride-based phosphors such as KSF-based phosphors. Wavelength converting member 70 may contain one or more different types of wavelength converting materials. When a plurality of wavelength conversion substances are contained, for example, the wavelength conversion member 70 should contain a β-sialon phosphor that emits greenish light and a fluoride-based phosphor such as a KSF-based phosphor that emits reddish light. can be done. Thereby, the color reproduction range of the planar light source 100 can be widened.

When using the light emitting element 20 that emits blue light, if it is desired to obtain red light as a planar light source, KSF phosphor (red phosphor) is preferably added to the wavelength conversion member in an amount of 60% by weight or more. is preferably contained in an amount of 90% by weight or more. That is, the wavelength conversion member contains a wavelength conversion substance that emits light of a specific color, so that light of a specific color can be emitted. Also, the wavelength conversion material may be a quantum dot. Within the wavelength converting member, the wavelength converting substance can, for example, be distributed substantially uniformly. Also, it may be unevenly distributed. Alternatively, a plurality of layers each containing a wavelength conversion substance may be laminated.

A resin or the like can be used as the base material for dispersing the wavelength conversion substance. As the resin material, for example, an epoxy resin, a silicone resin, a mixed resin thereof, or a translucent material such as glass can be used. From the viewpoint of light resistance and moldability of the wavelength conversion member 70, it is beneficial to select a silicone resin as the base material.
(light diffusion layer)

In addition to the wavelength conversion member 70, a light diffusion layer that diffuses or scatters the light emitted by the light emitting element 20 can be provided. As a result, local light concentration is avoided on the light extraction surface of the planar light source on which the plurality of light emitting elements 20 are arranged, and planar light emission with little luminance unevenness is obtained. The light diffusion layer is configured by dispersing a light diffusion material in a resin. Inorganic particles such as TiO ₂ , SiO ₂ , Al ₂ O ₃ or glass filler can be suitably used as the light diffusing material. As the light diffusing material, it is also possible to use fine particles obtained by processing a white resin or metal, which is a light reflecting member. These light diffusing materials are irregularly contained inside the base material, so that the light passing through the light diffusing layer is irregularly and repeatedly reflected, diffused in multiple directions, and diffused into the surface. To prevent uneven brightness from occurring by suppressing local concentration of light on a light extraction surface of a light source. Thermosetting resins such as silicone resins and epoxy resins can be suitably used as resins forming the light diffusion layer. The light diffusing portion preferably has a reflectance of 60% or more, preferably 90% or more, with respect to the light emitted from the light emitting element 20 . Note that this light diffusion layer can be omitted depending on the configuration and application of the planar light source.
[Embodiment 2]

In the light shielding member 54, the hole 56 may have a constant opening width in the thickness direction of the light shielding member 54 as shown in FIG. 3, or the inner surface of the hole 56 may be inclined.

Further, a step can be provided on the inner surface of the hole portion 56 . Such an example is shown in FIG. 6 as a planar light source 200 according to the second embodiment. The planar light source 200 shown in this figure has a hole portion 56B whose opening end is stepped. By doing so, the light extraction efficiency can be improved.
[Embodiment 3]

In the example of FIG. 3 described above, the translucent member 60 is provided integrally with the inner surface of the hole portion 56 defined by the light shielding member 54 and the member arranged on the upper surface of the light shielding member 54 . However, the present invention is not limited to this configuration, and can include a plurality of translucent members. Such an example is shown in FIG. 7 as a planar light source 300 according to the third embodiment. In this figure, the same reference numerals are assigned to the same members as in the first and second embodiments described above, and detailed description thereof will be omitted as appropriate. The light-transmitting member 60 shown in FIG. 7 includes a light-transmitting member 60a arranged inside the hole 56 partitioned by the light-shielding member 54C, and a light-transmitting member 60a and the light-transmitting member 54C covering the upper surfaces of the light-transmitting member 60a and the light-shielding member 54C. It is arranged separately from the elastic member 60b. It is preferable to use the same material for the translucent member 60a and the translucent member 60b. However, different materials with similar refractive indices may be used.
[Manufacturing method of planar light source]

Next, a method for manufacturing a planar light source will be described with reference to FIGS. 8 to 28. FIG. First, an intermediate 2 shown in FIG. 21 is prepared.
(Step of preparing intermediate 2)

The intermediate 2 shown in FIG. 21 includes a support member 51, a composite substrate 50 including a wiring layer 40 arranged on the support member 51, and a light emitting element 20 mounted on the wiring layer 40 of the composite substrate 50. Hereinafter, the steps of preparing the first intermediate 1 will be described with reference to FIGS. 8 to 16. FIG.
(Step of Arranging Light Emitting Element 20)

First, as shown in FIG. 8, the light emitting element 20 is arranged on the supporting portion 10 with the second translucent member 13 interposed therebetween. The light emitting element 20 is arranged with the electrode forming surface 20a facing upward and the light extraction surface 20b facing downward. The light emitting element 20 can be arranged so as to be partially embedded in the second translucent member 13 . It is preferable to form unevenness on the light extraction surface of the light emitting element 20 .

In addition, in the first intermediate 1, a plurality of light emitting elements 20 can be arranged at predetermined intervals. In this case, the element electrodes 21 of the light emitting elements 20 can be electrically connected to each other by the wiring layer 40 in the step of forming the wiring layer 40 to be described later.

The support portion 10 is capable of mounting the light emitting element 20 thereon. For example, a glass substrate, a sapphire substrate, or the like can be suitably used as the support portion 10 . Also, a sapphire substrate having both surfaces (upper surface and lower surface) polished can be preferably used as the support part 10 . Although the shape of the support portion 10 is not particularly limited, it is preferable that the upper surface is flat. The supporting portion 10 and the light emitting element 20 are bonded together by the second translucent member 13 . As the second translucent member 13, for example, VPA manufactured by Nippon Steel Chemical Co., Ltd. can be used.

A photosensitive resin layer is arranged as a peeling layer 11 on the upper surface of the supporting portion 10 . A second translucent member 13 is arranged on the upper surface of the release layer 11 with a protective layer 12 interposed therebetween. The peeling layer 11 is for separating the light emitting element 20 from the supporting portion 10 later by irradiating light.

Next, as shown in FIG. 9, the second translucent member 13 in the region other than the mounting region of the light emitting element 20 is removed by etching. Reactive ion etching (RIE) can be suitably used for etching. The protective layer 12 serves to prevent the release layer 11 from being etched. As a material for the protective layer 12, it is preferable to use a metal. Ti or the like can be used as the metal of the protective layer 12 .
(Step of forming first coating layer 30)

Next, as shown in FIG. 10 , a first coating layer 30 is formed on the supporting portion 10 and around the light emitting element 20 . The first coating layer 30 is provided by coating the material of the first coating layer 30 on the support portion 10 . The coating method is not particularly limited, and may be a spin coating method using a spin coater or discharge using a dispenser. The first coating layer 30 preferably uses a member made of an organic material. As a result, it can be easily removed by etching in the step of removing the first covering layer 30, which will be described later. As the organic substance, for example, polyimide (PI), acrylic resin, or the like can be used.

When a resist is used as the first coating layer 30, as shown in FIG. 10, after providing the resist so as to cover the support section 10 and the light emitting element 20, a mask M provided in a shape covering the upper side of the light emitting element 20 is applied. exposed through and developed. As a result, as shown in FIG. 11, an opening is formed through which the electrode forming surface 20a of the light emitting element 20 is exposed. In the examples shown in FIGS. 10 and 11, an example using a so-called negative resist in which the exposed portion remains after exposure and development is shown, but a positive resist in which the exposed portion is removed after exposure and development is used. may be used. As such a resist, a material containing polyimide, acrylic resin, or the like as a main component can be used.
(Step of forming wiring layer 40)

Next, the wiring layer 40 is formed over the first covering layer 30 from the device electrode 21 of the light emitting device 20 . The wiring layer 40 is formed by stacking a first metal layer 41 and a second metal layer 42 .

In the step of forming the wiring layer 40, first, as shown in FIG. 12, the first metal layer 41 is formed on substantially the entire surfaces of the device electrodes 21 of the light emitting device 20 and the first covering layer 30 by sputtering or the like. The first metal layer 41 is used as a seed layer when forming the second metal layer 42 by electroplating in the subsequent step of forming the second metal layer 42 . As the laminated structure of the first metal layer 41, for example, Al/Ti and the like are listed from the support section 10 side.

Next, as shown in FIG. 13, a resist RS is provided on the first metal layer 41 . The resist RS has multiple openings. In plan view, the opening of the resist RS overlaps with at least part of the element electrode 21 . In addition, the opening of the resist RS is larger than the element electrode 21 in plan view. The interval between the openings provided on one light emitting element 20 is wider than the interval between the positive and negative element electrodes.

Next, as shown in FIG. 14, a second metal layer 42 is formed in the opening of the resist RS by electroplating. The second metal layer 42 is formed by using the first metal layer 41 as a seed layer for electroplating, that is, as a current path, and growing it by plating within the opening of the resist RS. The second metal layer 42 may be Cu, for example.

Next, as shown in FIG. 15, the resist RS is removed. Thereby, the second metal layer 42 is formed as part of the wiring layer 40 .

Subsequently, as shown in FIG. 16, part of the second metal layer 42 is removed by etching to thin the second metal layer 42, and the first metal layer 42 is removed from the region where the second metal layer 42 is not formed. Layer 41 is removed. By removing part of the second metal layer 42 and the first metal layer 41 at the same time, etching can be performed without providing a mask or the like. As a result, the wiring layer 40 in which the first metal layer 41 and the second metal layer 42 are laminated is formed from the device electrode 21 of the light emitting device 20 to the first covering layer 30 . In the step of forming the second metal layer 42, if the second metal layer 42 is formed to be thin, the step of thinning the second metal layer 42 can be omitted. In this case, the step of removing the first metal layer 41 in the region where the second metal layer 42 is not formed can be performed before or after the step of forming the second metal layer 42 . A second wiring layer can be formed by laminating a third metal layer and a fourth metal layer on the wiring layer 40 .

As described above, since the wiring layer 40 is formed with respect to the element electrode 21 of the light emitting element 20, even if the light emitting element 20 is displaced in the process of arranging the light emitting element 20, the wiring layer 40 can be formed at the position where the wiring layer 40 is provided. can be adjusted. As a result, poor connection due to misalignment between the element electrode 21 of the light emitting element 20 and the wiring layer 40 can be suppressed as compared with the case where the light emitting element is arranged with respect to the wiring layer on the substrate.

The first intermediate 1 is prepared as described above. Such a first intermediate 1 may be prepared by purchase, or may be prepared by performing a part or all of the steps for preparing the first intermediate 1.

While preparing the first intermediate 1, a reinforcing substrate 52 coated with a light reflecting resin 51b is prepared. Then, as shown in FIG. 17, the first intermediate 1 is turned upside down on the light-reflecting resin 51b, and pressed with the surface on the wiring layer 40 side facing the light-reflecting resin 51b. Here, the first intermediate 1 is bonded with a support member 51 to a wafer such as a base glass substrate having a release sheet on the upper surface thereof and a reinforcing substrate 52 such as a BN substrate placed thereon. Preferably, they are bonded by pressing in a vacuum. As a result, the support member 51 and the reinforcing substrate 52 can be collectively joined to the first intermediate body 1, so that even if the support member 51 is made thin, warping and wrinkles can be suppressed. Here, the first intermediate 1 is pressed against the uncured or semi-cured light reflective resin 51b. As used herein, the term “semi-cured” refers to a state in which the curing of the resin is stopped in the middle, and the term “semi-cured light-reflective resin” refers to a state in which curing is further advanced by heating during the curing process. refers to a light-reflective resin in a state in which it is possible to By using the uncured or semi-cured light reflective resin 51 b , the side and bottom surfaces of the wiring layer 40 (the surface opposite to the surface facing the first covering layer 30 ) can be covered with the support member 51 . In the example shown in FIG. 17, a glass substrate is used for pressing. These glass substrates for pressing PG are preferably provided with a release PET sheet or the like on the surface thereof.

Next, the support member 51 is formed by curing the light reflecting resin 51b. First, as shown in FIG. 18, the light reflecting resin 51b is cured while being pressed. As described above, the light reflective resin 51b is a thermosetting resin such as a silicone resin, so it is heated. For example, it is heated to 150° C. for several hours. Then, as shown in FIG. 19, after releasing the glass substrate PG for pressing, excess light-reflecting resin and the like are removed. In this example, the supporting member 51 is applied on the reinforcing substrate 52 in advance. 52 may be attached.

Next, as shown in FIG. 20, the support portion 10 is removed. The removal of the supporting portion 10 can be performed by laser lift-off or the like. A peeling layer 11 is provided in advance on the supporting portion 10 so that the supporting portion 10 can be easily peeled off.

Further, unnecessary portions such as the peeling layer 11 are removed. Here, as shown in FIG. 21, the polyimide resin of the first coating layer 30 is removed by RIE. As described above, the intermediate 2 in which the plurality of light emitting elements 20 are arranged on the composite substrate 50 is obtained. Such an intermediate 2 may be prepared by purchase, or may be prepared by performing a part or all of the steps for preparing the intermediate 2 .
(Step of Arranging Covering Member 31)

As shown in FIG. 22, a plurality of covering members 31 are arranged separately from each other on the intermediate body 2 thus obtained. Each covering member 31 is arranged so as to cover the top surface and side surfaces of the light emitting element 20 and the composite substrate 50 around the light emitting element 20 . A resist can be suitably used for the covering member 31 . Acrylic resin or the like can be used as the resist material. An uncured resist material is applied on the upper surface of the composite substrate 50 so as to bury the light emitting elements 20 , and is cured to form the covering member 31 .

The shape of the covering member 31 may be a cylinder, a polygonal prism such as a quadrangular prism or a hexagonal prism, a truncated cone, a truncated polygonal pyramid, or the like. It is preferable that the light emitting element 20 is arranged at the center of the covering member 31 in plan view.

The terminal portion 43 of the wiring layer 40 connected to the outside is also arranged on the upper surface so as to be covered with the covering member 31 .
(Step of arranging light shielding member)

A light shielding member 54 is arranged so as to fill the space between the covering members 31 thus formed. In the example shown in FIG. 23, the light shielding member 54 is formed continuously from between the covering members 31 so as to cover the upper surfaces of the covering members 31, but the light shielding member 54 is formed at the same height as the covering member 31. You may A resin containing a light reflecting material is used to form the light shielding member 54 . For example, by filling uncured silicone resin between the covering members 31 and curing it, the light shielding member can be formed so as to surround the plurality of covering members 31 .
(Step of Exposing Covering Member 31)

Next, as shown in FIG. 24, part of the surface of the light shielding member 54 is removed to expose the covering member 31 . For example, the upper surface of the light shielding member 54 is cut until the covering member 31 is exposed from the light shielding member 54 . This provides an advantage that the upper surface of the light shielding member 54 can be made flat. In the step of arranging the light shielding member, if the light shielding member 54 is formed at the same height as the covering member 31 and does not cover the upper surface of the covering member 31, the step of exposing the covering member 31 can be omitted.
(Step of removing covering member 31)

Furthermore, as shown in FIG. 25, by removing the covering member 31, a plurality of holes 56 surrounded by the light shielding member 54 are formed. The removal of the covering member 31 is performed, for example, by dry etching.
(Step of Arranging Translucent Member 60)

Then, the translucent member 60 is arranged in the plurality of holes 56 . Here, as shown in FIG. 26, a translucent member 60 is arranged so as to fill the upper surfaces of the hole 56 and the light shielding member 54 . A thermosetting resin such as a silicone resin can be used as the translucent member. In this way, the light emitted from the plurality of light emitting elements 20 partitioned by the light shielding member 54 is partially propagated between the adjacent light emitting regions via the translucent member 60, thereby reducing luminance unevenness and improving surface efficiency. It becomes possible to obtain a planar light source that approximates light emission.
(Step of providing necessary wiring to the terminal portion 43 of the wiring layer 40)

Furthermore, necessary wiring is performed on the terminal portion 43 of the wiring layer 40 . In the example shown in FIG. 27, a flexible substrate 44 is connected to the terminal portion 43 .

As described above, it is possible to obtain a compact planar light source having a plurality of light emitting elements 20 arranged in each hole 56 and partitioned by the light blocking member 54 .
(Step of Arranging Wavelength Conversion Member 70)

Furthermore, the wavelength converting member 70 can be arranged on the translucent member 60 and the light shielding member 54 . By providing the wavelength conversion member 70, the light emitted by the light emitting element 20 can be converted into light of different wavelengths by the wavelength conversion member 70, and the mixed color light can be emitted. For example, a planar light source capable of emitting white light can be obtained by using a blue light emitting diode as the light emitting element and a YAG phosphor that emits yellow fluorescence when excited by blue light as the wavelength conversion member 70 .

To dispose the wavelength conversion member 70, for example, the wavelength conversion member 70 is placed on the upper surface as shown in FIG. Then, the translucent resin is cured to bond the wavelength conversion member 70 to the translucent member.

The wavelength conversion member 70 is prepared in advance by dispersing a wavelength conversion material in a resin material serving as a base material and forming a sheet. Also, the wavelength conversion member 70 can have a multilayer structure. A wavelength converting member having a multilayer structure can include wavelength converting materials such as different types of phosphors in each layer. Alternatively, a translucent layer without wavelength converting material may be included.
(Step of forming a step on the inner surface of the hole portion 56 of the light shielding member 54)

As described above, the light shielding member 54 may have a flat inner surface of the hole 56, or may have a step as shown in FIG. Here, the process of forming a step on the inner surface of the hole of the light shielding member 54 will be described with reference to FIGS. 29 to 33. FIG. First, the covering member 31 is formed, the light shielding member 54 is arranged, and the covering member 31 is removed to form the hole portion 56A as shown in FIG. Although only one hole portion 56A is shown here for explanation, a plurality of hole portions 56A are actually formed in the composite substrate 50. As shown in FIG. In the following description, only one member is shown, but a plurality of members are similarly formed or removed on the composite substrate 50 .

Next, as shown in FIG. 30, the second covering member 32 is formed. Here, the second covering member 32 continues from the hole 56A and covers the upper surface of the light shielding member 54 to the periphery of the hole 56A. Such a second covering member 32 is formed separately for each hole 56A. The second covering member 32 can use the same material as the first covering layer 30 and the covering member 31 described above.

Furthermore, as shown in FIG. 31, a second light blocking member 54B is arranged. Here, the second light shielding member 54B is formed up to the upper surface of the second covering member 32 so as to fill the space between the second covering portions. Then, as shown in FIG. 32, the upper surface of the second light shielding member 54B is removed to expose the second covering member 32. Then, as shown in FIG. The same material as that of the light shielding member 54 described above can also be used for the second light shielding member 54B.

Then, the second covering member 32 is removed. In this manner, as shown in FIG. 33, a hole portion 56B is formed with a step at the open end of the hole portion 56A.

Further, by repeating the same steps, it is also possible to increase the number of steps.

Alternatively, steps can be formed by changing the exposure intensity and the exposure pattern during etching such as RIE. Such an example will be described with reference to FIGS. 34 and 35. FIG. First, in the same manner as the steps up to FIG. 20 described above, a light reflective resin that will be the light shielding member 54 is applied to the entire surface of the intermediate body 2 in which a plurality of light emitting elements 20 are arranged on the composite substrate 50 is prepared. In this state, as shown in FIG. 34, the first exposure (first exposure) is performed through the first mask M1. The opening area of the first mask M1 is designed to be the opening area of the hole portion 56A. The exposure intensity of the first exposure is set to an intensity that can remove all the light-reflective resin (light shielding member 54) on the composite substrate 50 by etching, that is, a relatively strong exposure intensity.

Next, the mask is changed to the second mask M2 and continuous exposure is performed. The opening area of the second mask M2 used for the second exposure (second exposure) is designed so that the opening area of the hole 58B is larger than that of the hole 56A as shown in FIG. The exposure intensity of the second exposure is set lower than the exposure intensity of the first exposure so that the hole 56A is formed, that is, the light shielding member 54 corresponding to the thickness of the hole 56A remains. Since the hole portions 56A and the hole portions 56B are formed in the light shielding member 54 in this manner, the planar light source 200 having the stepped light shielding member 54 as shown in FIG. 32 is obtained.
[Embodiment 4]

In the example of the planar light source 400 according to Embodiment 4 shown in FIG. It has an intersection that three-dimensionally intersects via the insulating member 48 . The insulating member 48 may be disposed between the first wiring layer 40A and the second wiring layer 40B in a region where the first wiring layer 40A and the second wiring layer 40B overlap at least when viewed from above. As the insulating member 48, a photosensitive insulating resin commonly used as an interlayer insulating film for multilayer wiring, such as a photosensitive acrylic resin, a photosensitive silicone resin (for example, SINR-3170 manufactured by Shin-Etsu Chemical Co., Ltd.), or a photosensitive epoxy resin. A resin, photosensitive polyimide, or the like can be used. A light shielding member 54 is arranged so as to cover the upper surfaces of the supporting member 51, the insulating member 48, the first wiring layer 40A and the second wiring layer 40B. The light shielding member 54 has a plurality of holes 56 . The light emitting element 20 is connected to the wiring layer 40 within the hole 56 . Although FIG. 36 does not show the translucent member 60 , the translucent member 60 may be provided inside the hole 56 . According to this embodiment, it is possible to realize a wiring layout in which the first wiring layer 40A and the second wiring layer 40B intersect, so that it is possible to easily form a circuit necessary for local dimming.

In the example of the planar light source 500 according to Embodiment 5 shown in FIG. 37, the translucent member 60 is arranged on the light emitting element 20, the support member 51, the first wiring layer 40A and the second wiring layer 40B. In planar light sources 400 and 500 shown in FIGS. 36 and 37, the side surfaces and bottom surfaces of the first wiring layer 40A and the second wiring layer 40B are embedded in the supporting member 51, the supporting member 51, the insulating member 48, the The upper surfaces of the first wiring layer 40A and the second wiring layer 40B are arranged substantially on the same plane. The lower surface of the translucent member 60 provided thereon is a substantially flat surface. Thereby, the light emitted from the light emitting element 20 can be spread within the translucent member 60 .
[Embodiment 6]

Also, a light guide plate may be added to the upper surface of the planar light source 400 shown in FIG. Such an example is shown in the sectional view of FIG. 38 as a planar light source 600 according to the sixth embodiment. A planar light source 600 shown in this figure has a light guide plate 80, a wavelength conversion member 70, and a prism sheet 90 arranged on the upper surface of the planar light source 400 according to the fourth embodiment. With such a configuration, the light emitted from the light emitting surface of the planar light source 400 can be reflected upward, and the brightness of the planar light source 500 from the front can be improved. In FIG. 38, the same reference numerals are assigned to members that are the same as those described above, and detailed description thereof will be omitted. In addition, in the figure, the planar light source 400 is schematically illustrated.

A cross-sectional view of the light guide plate 80 is shown in FIG. 39, a plan view with a partially enlarged view thereof is shown in FIG. 40, and a bottom view with a partially enlarged view thereof is shown in FIG. The light guide plate 80 shown in these figures has a plurality of first concave portions 81 on its upper surface. Each first concave portion 81 is arranged substantially directly above the light emitting element 20 . The first concave portion 81 can have, for example, an inverted truncated cone shape.

A plurality of protrusions 82 are arranged in a region of the upper surface of the light guide plate 80 that does not overlap with the first recesses 81 . It is preferable that the plurality of protrusions 82 be arranged at even intervals. Each projection 82 has a circular shape when viewed from above, as shown in the partial enlarged view of FIG. The diameter of the circular protrusion 82 can be, for example, 10 μm or more and 300 μm or less. By suppressing total reflection inside the light guide plate 80, the convex portion 82 can exhibit the effect of increasing light extracted from the upper surface. The vertical cross-sectional shape of such projections 82 can take various shapes such as a hemispherical shape, a conical shape, a pyramidal shape, and a truncated pyramidal shape. In addition, recesses may be arranged instead of the protrusions 82 . In this case, the shape of the recess when viewed from above can be circular. Moreover, the cross-sectional shape of the concave portion can adopt various shapes such as a hemispherical shape, a conical shape, a pyramidal shape, and a truncated pyramidal shape.

In addition, as shown in the bottom view of FIG. 41, a plurality of second recesses 83 are arranged over the entire lower surface of the light guide plate 80 and are smaller than the arrangement pitch of the light emitting elements 20 . As shown in the enlarged perspective view of FIG. 42, each second concave portion 83 has a truncated quadrangular pyramid shape. The square bottom surface of the second concave portion 83 is rotated by 45° and arranged in a large number in an oblique posture as shown in the partial enlarged view of FIG. 41 . The opening width of the second concave portion 83 can be about 0.5 μm or more and 10 μm or less.

By adding the light guide plate 80 having such a plurality of convex portions 82 , first concave portions 81 and second concave portions 83 , it is possible to diffuse the light from the planar light source 400 .

The same configuration as that shown in FIG. 3 and the like can be used for the wavelength conversion member 70 . In the example of FIG. 38, as the wavelength conversion member 70, a laminate sheet in which both surfaces of a laminate of a sheet-like first wavelength conversion member 71 and a second wavelength conversion member 72 are coated with translucent protective films 73a and 73b can also be used. good. For example, PET or the like can be used as the protective films 73a and 73b. Furthermore, a dichroic mirror may be added to the lower surface side of the first wavelength conversion member 71 . A dichroic mirror can be provided between the first wavelength conversion member 71 and the protective film 73a. A dichroic mirror may be provided instead of the protective film 73a. By adding a dichroic mirror in this way, it is possible to suppress return of light (for example, yellow fluorescence) from the wavelength conversion member to the light source side, thereby contributing to improvement of light extraction efficiency and suppression of color unevenness.

In the example of FIG. 38, a red phosphor such as a KSF-based phosphor is used as the wavelength conversion substance contained in the first wavelength conversion member 71, and a β-sialon phosphor is used as the wavelength conversion substance contained in the second wavelength conversion member 72. and other green phosphors are used.

The prism sheet 90 is a composite prism film that improves the front brightness of the liquid crystal display. For such a prism sheet 90, for example, a brightness enhancement film (ASOC4, DBEF, BEF) manufactured by 3M Co., Ltd., or the like can be used.

The planar light source according to the present disclosure can be suitably used as a backlight for televisions, tablets, and liquid crystal display devices, for televisions, tablets, smartphones, smart watches, head-up displays, digital signage, bulletin boards, and the like. It can also be used as a light source for lighting, and can be used for emergency lighting, line lighting, various types of illumination, and in-vehicle installation.

DESCRIPTION OF SYMBOLS 100, 200, 300, 400, 500, 600... Planar light source 1... First intermediate body 2... Intermediate body 10... Support part 11... Release layer 12... Protective layer 13... Second translucent member 20... Light emitting element 20a ... Electrode forming surface 20b... Light extraction surface 21... Element electrode 30... First covering layer 31... Covering member 32... Second covering member 40... Wiring layer; 40A... First wiring layer; First metal layer 42 Second metal layer 43 Terminal portion 44 Flexible substrate 45 Mounting area 46 Extension area 48 Insulating member 50 Composite substrate 51 Supporting member 51b Light reflecting resin 52 Reinforcing substrate 54 Light shielding member; 54B Second light shielding member 56 Hole 56A Hole 56B Holes 60, 60a, 60b Translucent member 62 Adhesive layer 70 Wavelength conversion member 71 First wavelength conversion member 72 Second wavelength converting members 73a, 73b Protective film 80 Light guide plate 81 First convex portion 82 Convex portion 83 Second concave portion 90 Prism sheet M Mask RS Resist PG Glass substrate for pressing

Claims (6)

A method for manufacturing a planar light source,
a composite substrate including a support member and a wiring layer provided on the support member;
a plurality of light emitting elements arranged apart from each other on the wiring layer of the composite substrate;
providing an intermediate comprising
disposing a plurality of covering members so as to cover the top surface and side surfaces of the plurality of light emitting elements and the composite substrate around the plurality of light emitting elements;
arranging a light shielding member so as to fill the space between the covering members;
removing the covering member to form a plurality of holes ;
After the step of removing the covering member to form the plurality of holes,
a step of disposing a plurality of second covering members so as to continuously cover a portion of the upper surface of the light shielding member from the plurality of holes;
arranging a second light shielding member so as to fill the space between the second covering members;
a step of removing the second covering member to form a plurality of holes having steps at the opening ends of the holes;
disposing translucent members in the plurality of holes;
including
The method of manufacturing a planar light source, wherein the step of arranging the translucent member includes arranging the translucent member so as to fill the upper surface of the hole and the light shielding member. A method for manufacturing a planar light source according to claim 1,
The method of manufacturing a planar light source, wherein the step of removing the covering member includes the step of removing the covering member by dry etching. A method for manufacturing a planar light source according to claim 1 or 2,
The wiring layer has a terminal portion connected to the outside,
The method of manufacturing a planar light source, wherein the step of arranging the plurality of covering members includes the step of arranging the covering member so as to cover the terminal portion. A method for manufacturing a planar light source according to any one of claims 1 to 3, further comprising:
After the step of arranging the translucent member,
A method for manufacturing a planar light source, comprising the step of disposing a wavelength conversion member for converting light emitted from the light emitting element into light of a different wavelength on the translucent member and the light shielding member. A method for manufacturing a planar light source according to any one of claims 1 to 4,
The step of arranging the light shielding member includes the step of arranging the light shielding member continuously from between the covering members so as to cover the upper surface of the covering member,
The planar light source manufacturing method further comprises:
A method for manufacturing a planar light source, comprising, after the step of arranging the light shielding member, removing part of the surface of the light shielding member to expose the covering member. A method for manufacturing a planar light source according to any one of claims 1 to 5,
A method for manufacturing a planar light source , wherein the light shielding member is made of a resin containing a light reflecting material.

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