JP7557129B2 - Surface emitting light source and its manufacturing method - Google Patents

Description

This disclosure relates to a surface-emitting light source and a method for manufacturing the same.

It has been known that via conductors are formed in via holes formed in a substrate by electroless copper plating or electrolytic copper plating (see Patent Document 1). When forming via conductors in via holes by plating, the wet process requires large-scale equipment and a complex manufacturing process. On the other hand, a dry process technology is also known in which a wiring substrate and a light-emitting module are connected while being heated by pressing.

JP 2006-237232 A

The objective of the present disclosure is to provide a surface-emitting light source and a manufacturing method thereof that can improve connection reliability in a dry process.

The surface-emitting light source according to the embodiment of the present disclosure includes a wiring board and a plurality of light-emitting modules arranged via an adhesive layer, the wiring board having a base material, a wiring layer formed on the back surface of the base material opposite the light-emitting modules, a conductive material filled across two or more of a plurality of vias formed for each wiring pad that is part of the wiring layer, and a covering layer that covers the wiring layer and has an opening that exposes a portion of the wiring pad, the light-emitting module is formed by aligning a plurality of light-emitting devices, and the opening is formed on the wiring pad with an opening area smaller than the area of the wiring pad.

The surface-emitting light source according to the embodiment of the present disclosure includes a wiring board and a plurality of light-emitting modules arranged via an adhesive layer, the wiring board having a base material, a wiring layer formed on the back surface of the base material opposite the light-emitting modules, a conductive material filled in vias formed for each wiring pad that is part of the wiring layer, and a covering layer that covers the wiring layer and has an opening that exposes a part of the wiring pad, the light-emitting module is formed by aligning a plurality of light-emitting devices, and the opening is formed on the wiring pad with an opening area smaller than the area of the wiring pad.

The method for manufacturing a surface-emitting light source according to an embodiment of the present disclosure includes a wiring board preparation step of preparing a wiring board having a substrate, a wiring layer provided on the back surface of the substrate, and a covering layer having a wiring pad that is a part of the wiring layer and covering the wiring layer to form an opening that exposes a part of the wiring pad within the area of the wiring pad; a through-hole forming step of providing an adhesive layer on the front surface side of the substrate and forming a through-hole that penetrates the wiring board and the adhesive layer through the opening in the wiring pad; a via forming step of temporarily connecting a plurality of light-emitting modules formed by aligning a plurality of light-emitting devices on the front surface side of the substrate via the adhesive layer to form the through-hole as a bottomed via; a filling step of filling the via with a conductive material; and a press processing step of joining the wiring board and the light-emitting module via the adhesive layer by heating while applying pressure by press processing.

Embodiments of the present disclosure can provide a wiring board with excellent connection reliability.

1 is a schematic diagram showing an enlarged view of a portion of the entire surface-emitting light source according to the embodiment as viewed from the rear surface side of a wiring substrate. FIG. FIG. 2 is a plan view illustrating a light-emitting module of the surface-emitting light source according to the embodiment. 2 is a cross-sectional view taken along line IIIA-IIIA in FIG. 1. 2 is a cross-sectional view taken along line IIIB-IIIB in FIG. 1. 2 is a cross-sectional view taken along line IIIC-IIIC in FIG. 1 . 4 is an enlarged schematic view showing the relationship between an opening and a wiring pad formed in a first covering layer provided in the surface-emitting light source according to the embodiment; FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. 4 is a flowchart showing a method for manufacturing a surface-emitting light source according to the embodiment. 4 is a schematic cross-sectional view of a wiring board prepared in a wiring board preparation step in the manufacturing method for the surface-emitting light source according to the embodiment; FIG. 10 is a schematic diagram showing a state in which a wiring substrate and an adhesive layer are bonded to each other and through holes are formed in a through hole forming step in the method for manufacturing a surface-emitting light source according to the embodiment. FIG. 5A to 5C are schematic diagrams illustrating a state in which vias have been formed in a via forming step in the method for manufacturing a surface-emitting light source according to the embodiment. 5A to 5C are schematic diagrams illustrating a state in which a conductive material is filled into a via in a filling step in the method for manufacturing a surface-emitting light source according to the embodiment. 5A to 5C are schematic cross-sectional views showing a press working step in the method for manufacturing the surface-emitting light source according to the embodiment; 5A to 5C are schematic diagrams illustrating a state in which a protective member is formed in the protective member formation step in the manufacturing method for the surface-emitting light source according to the embodiment. 10 is an enlarged plan view illustrating a first modified example of an opening in a first covering layer in the surface-emitting light source according to the embodiment; FIG. 13 is an enlarged plan view illustrating a schematic diagram of a second modified example of the opening of the first covering layer in the surface-emitting light source according to the embodiment. FIG. 13 is an enlarged plan view illustrating a schematic diagram of a third modified example of the opening of the first covering layer in the surface-emitting light source according to the embodiment. FIG. 13 is an enlarged plan view illustrating a schematic diagram of a fourth modified example of the opening of the first covering layer in the surface-emitting light source according to the embodiment. FIG. 10 is a schematic cross-sectional view showing another configuration of the wiring board in the surface-emitting light source according to the embodiment; FIG. 11A and 11B are schematic diagrams showing a first modified example of a press working step in the method for manufacturing a surface-emitting light source according to the embodiment; 11A and 11B are schematic diagrams showing a second modified example of the press working step in the method for manufacturing the surface-emitting light source according to the embodiment. 10 is a flowchart showing another method for manufacturing the surface-emitting light source according to the embodiment. 13 is an enlarged schematic view showing the relationship between an opening and a wiring pad formed in a first covering layer in another manufacturing method of the surface-emitting light source according to the embodiment. FIG. 13B is a cross-sectional view taken along line XIIIB-XIIIB in FIG. 13A. 13B is a cross-sectional view taken along line XIIIC-XIIIC in FIG. 13A. 13B is a cross-sectional view taken along line XIIID-XIIID in FIG. 13A. 13A and 13B are enlarged schematic views showing the relationship between the wiring pads and openings of other shapes formed in the first covering layer in another manufacturing method of the surface-emitting light source according to the embodiment. 14B is a cross-sectional view taken along line XIVB-XIVB in FIG. 14A. 14B is a cross-sectional view taken along line XIVC-XIVC in FIG. 14A. 14B is a cross-sectional view taken along line XIVD-XIVD in FIG. 14A. 5 is a plan view showing a first modified example of the filled state of the conductive member in FIG. 4 . FIG. FIG. 9B is a plan view showing a second modified example of the filling state of the conductive member in FIG. 9A . FIG. 9C is a plan view showing a third modified example of the filling state of the conductive member in FIG. 9B. FIG. 9D is a plan view showing a fourth modified example of the filling state of the conductive member in FIG. 9C. FIG. 9E is a plan view showing a fifth modified example of the filling state of the conductive member in FIG. 9D. 13 is a plan view showing a sixth modified example of the opening of the covering layer and the filling state of the conductive member. FIG. This is a cross-sectional view taken along line XVIA-XVIA in FIG. 15A. This is a cross-sectional view taken along line XVIB-XVIB in Figure 15A.

The drawings referred to in the following description of the embodiment are schematic illustrations of the present invention, and therefore the scale, spacing, and positional relationships of each component may be exaggerated, or some components may not be shown. The scale and spacing of each component may not be consistent. In the following description, the same names and symbols generally indicate the same or similar components, and detailed descriptions will be omitted as appropriate. In the configuration of the wiring board, the terms "upper," "lower," "left," and "right" are interchangeable depending on the situation. In this specification, "upper," "lower," and the like indicate the relative positions between components in the drawings referred to for explanation, and are not intended to indicate absolute positions unless otherwise specified.

[Surface emitting light source]
The surface-emitting light source 100 will be described with reference to FIGS.
The surface-emitting light source 100 includes a wiring board 20 and a plurality of light-emitting modules 10 via an adhesive layer (adhesive sheet) 30. The wiring board 20 includes a base material 11, a wiring layer (first wiring layer) 17 formed on the back surface of the base material 11 opposite to the light-emitting module 10, a conductive member 13 filled across two or more vias 16 among a plurality of vias 16 formed for each wiring pad 18 that is a part of the wiring layer (first wiring layer) 17, and a covering layer (first covering layer) 12 that covers the wiring layer (first wiring layer) 17, exposes a part of the wiring pad 18, and has an opening H formed therein that overlaps at least a part of the via 16. Furthermore, the light-emitting module 10 is formed by aligning a plurality of light sources 1. The opening H of the first covering layer 12 is formed on the wiring pad 18 with an opening area smaller than the area of the wiring pad 18.
Each component of the surface-emitting light source 100 will be described below.

[Wiring Board]
The wiring board 20 has a first wiring layer 17 formed on the base material 11, and a wiring pad 18 that is continuous with the first wiring layer 17 and has a plurality of vias 16 formed therein. The vias are through holes provided in the wiring pad 18 and the base material 11. In addition, the wiring board 20 has a wiring layer (hereinafter referred to as the first wiring layer) 17, a covering layer (hereinafter referred to as the first covering layer) 12 that covers the first wiring layer 17, and a conductive member 13 that fills the vias 16 formed in the wiring pad 18 that is a part of the first wiring layer 17, formed on the back side of the base material 11. Furthermore, a protective member 19 that protects the conductive member 13 may be formed as described later. In addition, the wiring board 20 has a wiring layer (hereinafter referred to as the second wiring layer) 14 and a covering layer (hereinafter referred to as the second covering layer) 15 that covers the second wiring layer 14 formed on the front side. The wiring board 20 is formed to have a plurality of light-emitting modules 10 on the front side via an adhesive layer 30.

The substrate 11 forming the wiring board 20 is made of a low-elasticity material, and is formed from an insulating resin material such as phenol resin, epoxy resin, polyimide resin, polyethylene terephthalate, polyethylene naphthalate, silicone resin, BT resin, polyphthalamide, etc. The substrate 11 may be a metal member having an insulating member formed in a layer on the surface thereof. The substrate 11 may be a rigid substrate or a flexible substrate. The wiring board 20 may be a laminate of a plurality of substrates 11. When vias are formed in each of the laminated substrates, the arrangement of the vias may be consistent or misaligned in plan view.
The first wiring layer 17 is wired in a predetermined circuit pattern on the back side of the base material 11. The first wiring layer 17 includes rectangular wiring pads 18 and thin-line wiring 18c connecting the wiring pads 18. The wiring pads 18 are formed by aligning the positive wiring pads 18A and the negative wiring pads 18B at a predetermined interval vertically and horizontally. In addition, the wiring 18c continuing to the positive wiring pads 18A and the negative wiring pads 18B is formed at a predetermined interval between the positive wiring pads 18A or the negative wiring pads 18B. In addition, in order to improve the adhesion between the wiring board 20 and the light-emitting module 10 in the press processing step S15 described later, the first wiring layer 17 can suppress the variation in the thickness of the wiring board 20 by increasing the area occupied by the wiring.

The wiring pad 18 is formed as a rectangular region with a line width wider than that of the thin-line wiring 18c. For example, the positive-side wiring pad 18A is arranged at a fixed interval from one side of the thin-line wiring 18c to form a fixed rectangle. The negative-side wiring pad 18B is arranged at a fixed interval between the positive-side wiring pads 18A to form a rectangle. In other words, the negative-side wiring pad 18B is arranged adjacent to the positive-side wiring pad 18A, and here, a pair of the positive-side wiring pad 18A and the negative-side wiring pad 18B are formed so as to be connected to the element electrode of one light source 1. The wiring pad 18 is formed to have a size larger than the opening area of the via 16 even if two or four vias 16 are formed.

The second wiring layer 14 is formed on the surface side of the substrate 11. The second wiring layer 14, together with the first wiring layer 17, is for supplying power from the outside to the light source 1. The second wiring layer 14 is formed in a thin line shape or a rectangular shape on the surface side of the substrate 11, which is preset to have a predetermined circuit pattern. It is preferable that the second wiring layer 14 is arranged so that the first wiring layer 17 and the portion without wiring do not overlap. By forming the second wiring layer 14 at a position where it does not overlap the first wiring layer 17 and the portion without wiring, at least one of the metal materials of the second wiring layer 14 or the first wiring layer 17 is present in the stacking direction in the thickness direction of the wiring board 20. Therefore, when the wiring board 20 is pressed together with the light-emitting module 10 as described later, the thickness variation of the wiring board 20 can be suppressed, resulting in a good bonding state.

The first wiring layer 17 and the second wiring layer 14 can be made of a metal material, for example, Ag, Al, Ni, Rh, Au, Cu, Ti, Pt, Pd, Mo, Cr, W, or other simple metals or alloys containing these metals. More preferably, Ag, Al, Pt, Rh, or other simple metals with excellent light reflectivity, or alloys containing these metals, can be used.

Here, the wiring pad 18 is formed so that two hole openings are formed continuously in the substrate 11 and communicate with the via 16. The via 16 is formed with a through hole 160 that penetrates the substrate 11 and the adhesive layer 30 as described later and has a bottom. The via 16 reaches the wiring layer 6 of the light-emitting module described later to form a bottomed hole with the wiring layer 6 of the light-emitting module as the bottom. The hole diameter of the via 16 is preferably, for example, φ0.1 mm or more, more preferably 0.3 mm or more, because this suppresses the variation in the connection resistance and stabilizes the brightness. In addition, it is preferable that the aspect ratio of the hole diameter and depth of each of the vias 16 is 0.75 or less, more preferably 0.5 or less, because it is easy to fill the via 16 with the conductive member 13. In addition, it is preferable that the gap G01 between the two vias 16 is 0.1 mm or more and 0.3 mm or less, because this reduces the connection resistance. The vias 16 are formed so that their opening shapes are, for example, circular, elliptical, rectangular, diamond, triangular, cross-shaped, etc. Also, the number of vias 16 may be one or more as long as they are formed in the wiring pad 18, and here, an example is shown in which two vias are formed with circular opening shapes.

The conductive member 13 fills the vias 16 to electrically conduct electricity so as to supply current from the outside to the aligned light source 1. In this embodiment, the conductive member 13 is filled across two vias 16. Also, each wiring pad 18 may have multiple vias 16, and each of the multiple vias 16 may be filled with the conductive member 13. Also, when each wiring pad 18 has multiple vias 16, the conductive member 13 may be filled across two or more of the multiple vias 16. The conductive member 13 is filled in the hole so as to span each via 16 from the back side of the wiring board 20. In other words, the conductive member 13 is filled in the vias 16 and is provided across a portion of the surface of the wiring pad 18 between the two vias 16. The portion of the surface of the wiring pad 18 is a portion of the periphery of the via 16. In other words, the conductive member 13 is provided so as to have a filled portion filled in the two vias 16 and an intervening portion intervening across the filled portion on the portion of the surface of the wiring pad 18. The intervening portion of the conductive member 13 is formed to a preset thickness, for example, equal to or less than the thickness of the first coating layer 12. It is preferable that the filled portion of the conductive member completely fills the via 16, but it is sufficient that the filled portion is provided so that at least electrical conductivity is obtained.

The conductive member 13 may be, for example, a mixture of a filler such as flake-shaped, scale-shaped or bark-shaped silver powder or copper powder and a thermosetting binder resin. It is also preferable to use a conductive member 13 that has as low a volume resistivity as possible and contains as little binder resin or solvent components as possible. As will be described in the manufacturing method below, the conductive member 13 is provided, for example, by screen printing through the openings of a mask so as to have a filling portion that fills two vias 16 and an intervening portion that is interposed on a part of the surface of the wiring pad 18 across each filling portion.

Once the conductive member 13 is provided, a protective member 19 such as an insulating resin may be formed to cover it. The protective member 19 protects the wiring pad 18 and the conductive member 13. This protective member 19 may be made of a phenyl silicone resin, a dimethyl silicone resin, or the like. In addition, a pigment may be added to the protective member 19 to make it opaque.

The first covering layer 12 is formed to cover a predetermined area with a predetermined thickness to protect the first wiring layer 17 and the like provided on the wiring board 20. This first covering layer 12 can be formed using the same resin as the protective member 19 or polyimide as a base material. The first covering layer 12 is provided to form an opening H on the wiring pad 18 with a size smaller than the area of the wiring pad 18. Therefore, a part of the first covering layer 12 covers a part of the wiring pad 18, and the remaining part of the wiring pad 18 is exposed from the first covering layer 12 by the opening H. The opening H of the first covering layer 12 is formed in a rectangular shape as an example. The opening H is formed so that the hole openings of the two vias 16 are arranged approximately in the center inside the rectangle of the opening H.

In other words, each opening H is formed to a size that exposes the multiple vias 16 formed in the wiring pad 18 from the first coating layer 12. The opening H has an opening periphery formed so as to be located away from the opening periphery of the vias 16. The position on the wiring pad 18 where the opening H is formed may be the center of the wiring pad 18, or may be a position along any side of the rectangular wiring pad 18. The opening H may also be formed in a shape that is symmetrical with respect to the center or center line of the via 16. Here, the opening H is formed in a rectangular shape so that the center line passing through the center of the rectangle approximately coincides with the center line passing through the center of the via 16.

The adhesive layer 30 bonds the light-emitting module 10 and the wiring board 20, and is made of a material with a low elastic modulus. In particular, the light-emitting module 10 is made of complex materials and is composed of the light-emitting element 2, light guide plate 7, light reflecting member 8, etc., which are made of different materials and have different physical properties, and an adhesive layer with a low elastic modulus is a preferred component for connecting to the wiring board 20. The elastic modulus of the adhesive layer 30 is preferably lower than that of the base material 11.

In general, in a wiring board as described in Patent Document 1, the number of coverlay openings formed in the coverlay, which is a covering layer for protecting the wiring, increases and the diameter becomes smaller. The coverlay openings of the wiring board used in the dry process are formed to be larger than the width of the wiring. Therefore, in the coverlay opening, a step occurs between the wiring and the substrate surface of the wiring board, and a step occurs between the coverlay and the substrate surface of the wiring board, and a space occurs due to the step. When performing press processing, it is difficult to apply a predetermined pressure to the part where a space occurs in the coverlay opening, and the smaller the coverlay opening, the harder the pressure is to be transmitted. Furthermore, when a wiring board with an elastic modulus of 2 GPa to 5 GPa and a light-emitting module including a hard polycarbonate or the like are press processed through a low-elasticity adhesive sheet with an elastic modulus of 100 MPa to 1 GPa, the low-elasticity adhesive sheet flows in the direction of the space where the pressure is smaller due to the step. As a result, a part of insufficient adhesion is formed between the adhesive layer and the light-emitting module, and there is a concern that bubbles due to the thermal expansion of the resin material are generated in the part of insufficient adhesion, which adversely affects the via connection and reduces the connection reliability.

On the other hand, since the opening H in this embodiment is formed on the wiring pad 18, no step is generated around the wiring pad 18 due to the thickness of the first wiring layer 17 and the base material 11 in the thickness direction of the base material 11. Therefore, when the elastic modulus of the base material 11 is 2 GPa or more and 5 GPa or less, and the elastic modulus of the adhesive layer 30 is 100 MPa or more and 1 GPa or less, when the wiring board 20 is pressed together with the light-emitting module 10, the thickness variation of the wiring board 20 can be suppressed, and the bonding state is good. As an example, the opening H has been described as a configuration in which one opening H is formed in a rectangular shape for the multiple vias 16 of one wiring pad 18, but the shape and number of the openings are not particularly limited. Also, as shown in other configurations described later, the opening may be formed with an opening area smaller than the area of the wiring pad 18 by opening an area on the wiring pad 18 where a part of the via 16 overlaps with the opening.

[Light-emitting module, light source, light-emitting element]
As shown in Fig. 1 to Fig. 6, the light source 1 includes, for example, a light-emitting element 2, a light-transmitting member 3 attached to the light-extraction surface side of the light-emitting element 2, a covering member (white resin) 4 directly or indirectly provided on the side of the light-emitting element 2, a light guide plate 7 having an optical function part 7a provided on the light-transmitting member 3, and a light reflecting member 8 covering the lower surface of the light guide plate 7, the side of the light-transmitting member 3, and the side of the covering member 4. The light source 1 connects the element electrode 5 of the light-emitting element 2 to a wiring layer 6 of the light-emitting module formed on the opposite side to the light guide plate 7. When one light source 1 is one cell SL (see Fig. 2), a plurality of cells are aligned adjacent to each other in the vertical and horizontal directions to form a light-emitting module 10. The light-emitting module 10 is, for example, composed of 16 cells, i.e., 4 cells x 4 cells. In the surface-emitting light source 100, for example, the light-emitting module 10 is formed by aligning 76 units.

The light-emitting element 2 can be, for example, a known semiconductor light-emitting element, and a light-emitting diode is exemplified as the light-emitting element 2. The light-emitting element 2 can be a light source that emits blue light, or a light-emitting element that emits a plurality of different color lights, and can emit white light by mixing red, blue, and green light. An element that emits light of any wavelength can be selected as the light-emitting element 2, and the composition, emission color, size, number, etc. of the light-emitting element to be used can be appropriately selected according to the purpose. For example, a light-emitting element that uses a nitride-based semiconductor (In _x Al _y Ga _1-x-y N, 0≦X, 0≦Y, X+Y≦1) or GaP can be used as an element that emits blue or green light. In addition, a light-emitting element that includes a semiconductor such as GaAlAs or AlInGaP can be used as an element that emits red light. In addition, a semiconductor light-emitting element made of a material other than the above can also be used, and various emission wavelengths can be selected depending on the material of the semiconductor layer and its mixed crystal degree.

The element electrode 5 of the light-emitting element 2 is formed on the opposite side to the translucent member 3 and is exposed from the bottom surface of the covering member 4 described below. The element electrode 5 has a negative electrode and a positive electrode spaced apart from each other, and may be arranged diagonally on the rectangular light-emitting element 2 or along a pair of two sides.

The light-transmitting member 3 is formed by including a phosphor in a light-transmitting material. The light-transmitting material is preferably a material having a higher refractive index than the material of the light guide plate 7. Although epoxy resin, silicone resin, a resin mixture of these, or glass can be used, it is preferable to select silicone resin from the viewpoints of light resistance and ease of molding.
The translucent member 3 has a different wavelength range that can be converted depending on the type of phosphor, and it is necessary to select an appropriate phosphor to convert to a desired wavelength. As the phosphor, for example, a YAG phosphor, a LAG phosphor, a chlorosilicate phosphor, a β-sialon phosphor, a CASN phosphor, a SCASN phosphor, a fluoride phosphor such as a KSF phosphor, etc. can be used. In particular, by using a plurality of types of phosphors in one translucent member 3, more preferably by the translucent member 3 including a β-sialon phosphor that emits green light and a fluoride phosphor such as a KSF phosphor that emits red light, it is possible to widen the color reproduction range of the light-emitting module.

Furthermore, the light-transmitting member 3 can emit light of a specific color by containing a phosphor that emits light of a specific color. The light-transmitting member 3 can also be made of quantum dots. There is no limitation on the arrangement of the wavelength conversion material in the light-transmitting member 3, and an effective arrangement can be selected, such as distributing the wavelength conversion material approximately uniformly, distributing the wavelength conversion material unevenly in a certain area, or stacking a plurality of layers each containing a different wavelength conversion material.
The light-transmitting member 3 may be configured so that a diffusion member is provided on the light-extraction surface side thereof.

The covering member 4 is placed on the underside of the light-transmitting member 3, directly on the side of the light-emitting element, or on the side of the light-emitting element via a light-transmitting adhesive member. It is desirable for the covering member 4 to have a reflectance of 60% or more, and preferably 90% or more, of the light from the light-emitting element 2. The covering member 4 is formed so that it has the same outer circumference as the light-transmitting member 3 in a plan view. In addition, the covering member 4 is formed so that the length from the underside of the light-transmitting member 3 (the upper surface of the covering member 4) to the underside of the covering member 4 can expose the element electrode 5.

The light guide plate 7 is a light-transmitting member that receives light from a light source and emits light in a planar form. The light guide plate 7 may have an optical function portion 7a on a first main surface that is a light-emitting surface, and may have a recess for accommodating the light-transmitting member 3 or the light source 1 on a second main surface that is opposite to the first main surface. The light guide plate 7 may also have a through hole that penetrates the first main surface and the second main surface and that can accommodate the light-transmitting member 3 or the light source 1. The light guide plate 7 may have a configuration in which a plurality of optical function portions 7a are provided on the first main surface.
As the material of the light guide plate 7, a resin material such as a thermoplastic resin such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, polyester, a thermosetting resin such as epoxy resin, silicone resin, or a material having light transmissivity such as glass can be used. In particular, a thermoplastic resin material is preferable because it can be efficiently manufactured by injection molding, and polycarbonate, which is highly transparent and inexpensive, is more preferable. In the surface-emitting light source 100 in which the wiring layer 6 of the light-emitting module is formed after the light-emitting element 2 is mounted on the light guide plate 7, a process in which high temperatures such as solder reflow are applied can be omitted, so that even a thermoplastic material with low heat resistance such as polycarbonate can be used. In addition, the light guide plate 7 can be molded by, for example, injection molding or transfer molding.

The optical function part 7a is provided to reflect the light from the light emitting element 2 and spread it in the radial direction, and to average the light emission intensity within the surface of the light guide plate 7. The optical function part 7a can be realized by various configurations, such as providing a member having a reflecting or diffusing function such as a lens on the light guide plate 7. For example, it can be configured to provide an interface between the material of the light guide plate 7 and a substance having a different refractive index, such as air. In addition, the optical function part 7a is formed as a space of an inverted cone recess, but its size and shape can be set appropriately. Specifically, it may be formed as a space of an inverted polygonal pyramid such as an inverted square pyramid or an inverted hexagonal pyramid. The optical function part 7a is a recess formed in this way, and can be configured to reflect the light irradiated at the interface between the light guide plate 7 and a substance having a different refractive index and the inclined surface of the recess to the side of the light emitting element 2, that is, in the radial direction with the optical function part 7a as the center. The optical function section 7a may be configured such that a reflective film such as a metal or a reflective material such as a white resin is provided in a recess having a linear or curved inclined surface in a cross-sectional view. The optical function section 7a is preferably provided at a position where the optical axis of the light-emitting element 2 and the optical axis at the center of the optical function section 7a (the apex of the recess) are approximately aligned on an extension line.

The light reflecting member 8 is a member that protects the light emitting element 2 and the light guide plate 7, and reflects light from the side of the light emitting element 2 to send it to the light emitting surface side. The light reflecting member 8 is preferably light reflective, and is required to have a reflectance of 60% or more, and preferably a reflectance of 90% or more, for the light emitted from the light emitting element 2. By forming the light reflecting member 8 from a reflective material, it becomes possible to efficiently take in the light emitted from the light emitting element 2 into the light guide plate 7. In addition, the light reflecting member 8 serves both as a member that protects the light emitting element 2 and as a reflecting member provided on the surface opposite to the emission surface of the light guide plate 7, and thus it becomes possible to reduce the thickness of the light emitting module 10.
The material of the light reflecting member 8 is preferably a resin containing a white pigment, etc. The light reflecting member 8 is a material used in a relatively large amount for the purpose of covering one surface of the light guide plate 7, and in order to reduce the cost of the light emitting module 10, it is preferable to use a silicone resin containing inexpensive titanium oxide.

As an example, the light-emitting element 2 and the light-transmitting member 3 are joined by a light-transmitting adhesive member. When the light-transmitting adhesive member is provided between the light extraction surface of the light-emitting element 2 and the light-transmitting member 3, it is preferable that the light-transmitting adhesive member is formed as a fillet on the side surface of the light-emitting element 2. Note that the light-transmitting adhesive member formed as a fillet on the side surface of the light-emitting element 2 can be a known adhesive such as silicone resin.
A wiring layer 6 of the light-emitting module, which is electrically connected to the element electrodes 5 of the multiple light-emitting elements 2, is provided on the lower surface side of the light reflecting member 8. The wiring layer 6 of the light-emitting module is formed on the surface that faces the light reflecting member 8 and the element electrodes 5 of the light-emitting elements 2. The wiring layer 6 of the light-emitting module is connected to the conductive members 13 of the vias 16 that are formed penetrating the wiring board 20 and the adhesive layer 30 from the back surface side of the wiring board 20, thereby electrically connecting the multiple light sources 1.

It is preferable that a covering layer of the wiring layer 6 of the light-emitting module is formed at a predetermined position of the wiring layer 6 of the light-emitting module, the covering layer being made of an insulating member 9 similar to the first covering layer 12. The insulating member 9 is formed in a film-like covering manner so as to form an opening in the wiring layer 6 of the light-emitting module in the region where the through hole 160 (see FIG. 8B ) of the wiring board 20 abuts.
Moreover, the light emitting module 10 becomes the surface emitting light source 100 by adhering to the wiring board 20 via the adhesive layer 30. The adhesive layer 30 used here is for adhering the light emitting module 10 and the wiring board 20, and is preferably made of a low elasticity material. This is to prevent warping of the surface emitting light source 100 due to the difference in linear expansion coefficient between the light emitting module 10 and the base material 11. Here, the material of the adhesive layer 30 is preferably a low elasticity sheet-like resin material such as an acrylic resin, a silicone resin, or a urethane resin. The elastic modulus of the adhesive layer 30 is preferably a material having a modulus of 100 MPa or more and 1 GPa or less. This is to prevent warping while ensuring the adhesion between the light emitting module 10 and the wiring board 20. In addition, the thickness of the adhesive layer 30 needs to absorb the step between the first wiring layer 17 and the second wiring layer 14 of the wiring board 20, and is preferably at least twice the thickness of the first wiring layer 17 or the second wiring layer 14, and more preferably at least four times the thickness. For example, when a copper foil of 18 μm is used for the second wiring layer 14, the thickness is 36 μm or more, more preferably 72 μm or more. It is preferable that the material of the adhesive layer 30 has high flame retardancy.

Next, a method for manufacturing the surface emitting light source 100 will be described with reference to FIGS.
The method for manufacturing the surface-emitting light source includes a wiring board preparation step S11 for preparing a wiring board 20 having a base material 11, a wiring layer (first wiring layer 17) provided on the back surface of the base material 11, and a first covering layer 12 that has wiring pads 18 that are part of the first wiring layer 17 and covers the first wiring layer 17 so as to form an opening H that exposes a part of the wiring pad 18 within the area of the wiring pad 18; and a bonding layer 30 provided on the front surface side of the base material 11 and bonding the wiring board 20 and the bonding layer 30 to the wiring pad 18 through the opening H. 8B ), which is a via formation process S13 for temporarily connecting a plurality of light-emitting modules 10 formed by aligning a plurality of light sources 1 on the front surface side of the base material 11 via an adhesive layer 30 to form through holes 160 (see FIG. 8B ) as bottomed vias 16; a filling process S14 for filling the vias 16 with conductive material 13; and a press processing process S15 for applying pressure and heating by press processing to bond the wiring board 20 and the light-emitting modules 10 via the adhesive layer 30.

The wiring board preparation process S11 is a process of preparing a wiring board 20 having a first wiring layer 17 and a first covering layer 12 on the back surface of the substrate 11. In the wiring board preparation process, wiring pads 18, which are part of a preset wiring pattern, and thin wire-like wiring 18c continuous with the wiring pads 18 are formed on the back surface of the substrate 11. The wiring pads 18 are arranged in a row and column direction with a predetermined interval between the positive electrode side wiring pads 18A and the negative electrode side wiring pads 18B. The first wiring layer 17 is formed of a circuit pattern from a metal layer, for example, copper foil. When forming a circuit pattern on the back surface or front surface of the substrate 11, for example, a metal layer can be laminated to form the circuit pattern. Examples of methods for forming a metal layer include a method of directly depositing the wiring pads 18 and the thin wire-like wiring 18c to form a predetermined wiring pattern by a plating method or a vapor phase film formation method (sputtering, ion plating, electron beam deposition, vacuum deposition, chemical deposition, etc.). From the standpoint of cost and productivity, it is advantageous to adhere the metal layer to the surface of the base material 11 with a urethane adhesive. In the wiring board preparation step S11, the second wiring layer 14 may be formed on the front side of the base material 11 together with the first wiring layer 17.

Next, the first covering layer 12 is formed on the base material 11 on which the first wiring layer 17 is formed, so as to form an opening H on the wiring pad 18, which is a part of the first wiring layer 17. The first covering layer 12 can be formed, for example, by a printing method such as screen printing or other known methods depending on the material of the covering layer to be adopted. The first covering layer 12 can be formed by screen printing using a mask or the like so that a part of the wiring pad 18 is exposed through the opening H on the wiring pad 18. The opening H has an opening area smaller than the area of the wiring pad 18, and is formed on the wiring pad 18 to a size that exposes the multiple vias 16 formed in the wiring pad 18 from the first covering layer 12 with one opening. In addition, when the second wiring layer 14 is formed, the second covering layer 15 is formed in the same manner as described above so as to cover the second wiring layer 14 at a predetermined position.

Then, the through hole forming process S12 is performed. In the through hole forming process S12, an adhesive sheet, which is the adhesive layer 30, is attached to the surface side of the prepared wiring board 20. The adhesive sheet used at this time has adhesive surfaces on both sides, and is used as an example here in which the adhesive surface appears by peeling off the separator (release paper) on the surface. In the through hole forming process S12, a through hole 160 is formed that penetrates the wiring board 20 and the adhesive layer 30 through the opening H of the wiring pad 18. The through hole 160 is provided through the opening H of the first coating layer 12 so as to penetrate the wiring board 20 and the adhesive layer 30 by drilling, punching, etc. The through hole 160 is provided so that multiple (here, two) through holes 160 are formed within the area of the wiring pad 18.

Then, the via formation process S13 is performed. In the via formation process S13, the separator (release paper) on the other side of the adhesive layer 30 that is adhered to the wiring board 20 is removed, and multiple light emitting modules 10 are temporarily connected to the other side of the adhesive layer. In this embodiment, the connection includes not only an electrical connection but also a connection between the wiring board 20 and the light emitting module 10. The light emitting module 10 has a lower surface formed so that a predetermined position of the wiring layer 6 of the light emitting module is exposed from the insulating member 9. In the via formation process S13, the wiring board 20 and the light emitting module 10 are temporarily connected via the adhesive layer 30 so that the wiring layer 6 of the light emitting module 10 faces the hole opening on the front side of the through hole 160 formed in the wiring board 20. Then, in the via formation process S13, the light emitting module 10 is temporarily connected to the front side of the wiring board 20 via the adhesive layer 30, so that one end side of the through hole 160 is blocked, and the through hole 160 is formed as a bottomed via 16.

The light emitting module 10 used in the via formation step S13 is prepared by the following manufacturing process, for example. That is, a light guide plate 7 on which an optical function portion 7a is formed in advance and a recess for accommodating the light-transmitting member 3 is prepared. Then, the light-transmitting member 3 is placed in the recess of the light guide plate 7, and the light extraction surface of the light emitting element 2 is bonded to the light-transmitting member 3 with an adhesive such as resin. Furthermore, after providing the light reflecting member 8, the wiring layer 6 of the light emitting module that connects the element electrodes 5 of the light emitting element 2 is formed. Then, the insulating member 9 made of a protective insulating member is formed at a predetermined position on the lower surface of the wiring layer 6 and the light reflecting member 8 of the light emitting module, thereby preparing the light emitting module 10.
In the via formation process S13, the wiring layer 6 of the light-emitting module is faced to the through hole 160 that penetrates the wiring board 20 and the adhesive layer 30, so that the through hole 160 becomes a via 16, and each of the multiple light-emitting modules 10 is temporarily connected to the wiring board 20 via the adhesive layer 30.

Next, the filling step S14 is performed. In the filling step S14, the via 16 is filled with a conductive member 13 such as a conductive paste. In this filling step S14, the via 16 is filled with the conductive member 13, and the conductive member 13 is further provided on a portion of the surface of the wiring pad 18 so as to span the two vias 16. In the filling step S14, for example, a mask having an opening hole is used. As an example, the opening of the mask is formed in an oval shape that connects two via openings on the upper surface of the via 16. In this embodiment, the oval shape refers to a ring shape that has a major axis and a minor axis and includes at least two curved lines. The opening of the mask is formed and arranged for each wiring pad 18. Therefore, when the conductive paste is supplied while moving the squeegee in a printing operation such as screen printing, the conductive member 13 is filled into the via 16 through the opening of the mask and is provided on a portion of the surface of the wiring pad 18. The conductive member 13 is printed with a filling portion that fills the via 16 and an intermediate portion that is provided on a portion of the surface of the wiring pad 18. In screen printing, the squeegee may move once or may go back and forth multiple times.

Then, the pressing process S15 is performed. In the pressing process S15, the conductive member 13 is hardened and the wiring board 20 and the light emitting module 10 are connected via the adhesive layer 30. In the pressing process S15, the intervening portion of the conductive member 13 can be hardened by being thinner than when it is provided through the opening of the mask. In the pressing process S15, for example, pressing is performed while applying heat using upper and lower hot plates HL1 and HL2 whose temperature can be controlled. The hot plates HL1 and HL2 may be pressed with a release film provided thereon. In the pressing process S15, the hot plates HL1 and HL2 are pressed while heated to a predetermined temperature, and the adhesive surface of the adhesive layer 30 is hardened, and the wiring board 20 and the light emitting module 10 are connected via the adhesive layer 30.

In the press processing step S15, when the upper and lower heating plates HL1 and HL2 press the wiring board 20, there is no exposed area of the substrate 11 around the wiring pad 18, so no space is generated between the substrate 11 and the first covering layer 12 due to the opening H. In other words, the opening H is formed on the wiring pad 18 with an opening area smaller than the area of the wiring pad 18. Therefore, when the first covering layer 12 in the opening H portion is pressed by the heating plates HL1 and HL2, the wiring pad 18 is pressed through the first covering layer 12. Therefore, there is no part where the wiring board and the light emitting module 10 are pressed through a space as in the conventional case, and the wiring board 20 and the light emitting module 10 are pressed with an appropriate pressure even inside the opening H, and are connected to both sides of the adhesive layer 30 without air bubbles.

Note that the press processing step S15 may be followed by a protective member forming step S16. The protective member forming step S16 is a step of forming a protective member 19, which is an insulating resin, from above the conductive member 13 pressed in the press processing step S15. In the protective member forming step S16, the protective member 19, which is an insulating resin, is supplied from one side of the substrate 11 so as to cover the wiring pad 18 and is pressed. Note that the protective member 19 is formed so as to cover the conductive member 13 and to be higher than the height of the first coating layer 12. Also, if the conductive member 13 does not completely fill the hole of the via 16 and there is a gap, the protective member 19 will also fill the hole.

As described above, the surface-emitting light source 100 is formed on the wiring pad 18 of the wiring board 20 with the opening H of the first covering layer 12 being smaller than the area of the wiring pad 18. Therefore, the wiring board 20 and the light-emitting module 10 can be pressed so that a set pressure is applied over the entire surface via the adhesive layer 30. Therefore, the surface-emitting light source 100 does not cause insufficient adhesion, prevents the generation of air bubbles at the interface between the adhesive layer 30 and the wiring layer 6 of the light-emitting module due to thermal expansion of the resin member, does not adversely affect the via connection, and can improve the connection reliability. In addition, in the manufacturing process of the surface-emitting light source 100, the wiring board 20, the adhesive layer 30, and the connection position of the light-emitting module can be appropriately pressed, and the volatile components of the conductive member 13 can be released from the opening H, so that pressure can be applied more appropriately than in the conventional configuration. In addition, in the surface-emitting light source 100 and its manufacturing method, it is possible to improve the adhesion of the adhesive layer 30 and reduce the via resistance.

The shape and number of openings H in the first coating layer 12 formed on the wiring pad 18 are not limited, and may be as shown in Figures 9A to 9D. Below, first to fourth modified examples of the openings H are described. The shape of the opening hole of the via 16 has been described as being round, but it is not particularly limited and may be rectangular, elliptical, triangular, cross-shaped, hexagonal, etc.

9A, an opening H1 may be formed for each of two (multiple) vias 16. The openings H1 are a first rectangular opening H11 formed in a position facing one of the vias 16 and a second rectangular opening H12 formed in a position facing the other via 16, which are adjacent to each other and spaced apart from each other via the first coating layer 12. The first rectangular opening H11 is formed so that a part of the edge of the hole opening of the via 16 contacts one side of the upper end of the rectangle. On the other hand, the second rectangular opening H12 is formed so that a part of the hole opening of the via 16 contacts one side of the lower end of the rectangle opposite the first rectangular opening H11.

The first rectangular opening H11 and the second rectangular opening H12 are formed adjacent to one via 16, and a part of the opening and a part of the first coating layer 12 are formed adjacent to a part of the outer periphery of the via 16. The opening H1 is formed symmetrically with respect to the center line connecting the centers of the vias 16 in the vertical direction. Since the opening H1 is formed by the first rectangular opening H11 and the second rectangular opening H12, it can be accommodated even if the vias 16 are formed at extremely distant positions on the wiring pad 18. In the opening H1, the via 16 is located on one side offset from the center of the first rectangular opening H11, and the via 16 is located on the other side offset from the center of the second rectangular opening H12, but the via 16 may be formed at a position in the center.

9B, the opening H2 may be configured to have a first rectangular opening H21 and a second rectangular opening H22 formed in a rectangular shape with a predetermined gap between the left and right of the vertically aligned vias 16. A portion of the first rectangular opening H21 is formed so as to overlap a portion of the vias 16 on one side (right side) from the center of the vias 16 across the multiple vias 16. The second rectangular opening H22 is formed so as to overlap a portion of the vias 16 on the other side (right side) from the center of the upper and lower vias 16. The first rectangular opening H21 and the second rectangular opening H22 are arranged adjacent to each other via a portion of the first coating layer 12 and a portion of the vias 16. The opening H2 is formed symmetrically with respect to a center line that connects the centers of the vias 16 in the vertical direction.

9C, the opening H3 may be formed with a first rectangular opening H31, a second rectangular opening H32, a third rectangular opening H33, and a fourth rectangular opening H34 aligned vertically and horizontally with respect to the vias 16 aligned vertically. In the opening H3, the first rectangular opening H31 and the second rectangular opening H32 are formed adjacent to one via 16 at a position where they partially overlap, and the third rectangular opening H33 and the fourth rectangular opening H34 are formed adjacent to one via 16 at a position where they partially overlap. Furthermore, in the opening H3, the first rectangular opening H31 and the third rectangular opening H33 are arranged adjacent to each other through the first coating layer 12, and the second rectangular opening H32 and the fourth rectangular opening H34 are arranged adjacent to each other through the first coating layer 12. This opening H3 is formed symmetrically in the left-right direction and in the vertical direction with respect to a center line connecting the centers of the vias 16 in the vertical direction.

As shown in FIG. 9D, opening H4 may be formed for each of a plurality of vias 16, and may have an opening shape that forms protruding side portions h41, h42, h43, and h44 that protrude so as to block part of the opening portion on the top, bottom, left, and right sides of the rectangular opening. Opening H4 is formed so that the vias 16 are positioned above and below the left and right protruding side portions h43 and h44, respectively. This opening H4 is formed symmetrically in both the left and right directions with respect to a center line that connects the centers of the vias 16 in the vertical direction, and also vertically symmetrically in the vertical direction.

In addition, in the surface-emitting light source 100, the wiring board 20 has been described as having a configuration in which the first wiring layer 17 and the first covering layer 12 are provided on the back surface of the base material 11, and the second wiring layer 14 and the second covering layer 15 are provided on the front surface of the base material 11. However, as shown in FIG. 10, a wiring board in which the first wiring layer 17 and the first covering layer 12 are provided only on the back surface of the base material 11 may also be used.

Furthermore, in the method for manufacturing the surface-emitting light source 100, the press working step may be performed as shown in FIGS. 11A and 11B.
As shown in FIG. 11A, in the press processing step S15, the press processing may be performed by a hot platen HL1, which is a mold, through a sheet Pc1 having a size L11 and a thickness L12 equivalent to the size L1 and the hole depth L2 of the opening H in a plan view. The sheet Pc1 used is preferably an absorbent sheet such as a paper sheet that can absorb the binder resin contained in the conductive member 13 melted during the press processing. In this way, in the press processing step S15, the via resistance can be reduced by performing the press processing while removing the excess binder resin with the sheet Pc1 when the conductive member 13 is hardened. The thickness L12 of the sheet Pc1 used here is preferably set in consideration of the conductive member 13 having a thickness between the two vias 16 on the wiring pad 18.

As shown in FIG. 11B, in the press processing step S15, the press processing may be performed using a hot platen HL11, which is a mold having a convex portion Dp whose concave and convex portions are opposite to the concave pattern from the surface of the substrate 11 to the surface of the first coating layer 12. The convex portion Dp has a first convex portion Dp1 corresponding to the opening H and a second convex portion Dp2 corresponding to a portion where there is no wiring such as the wiring pad 18. The first convex portion Dp1 is formed to have a size L21 and a convex height L22 equivalent to the size L1 and hole depth L2 of the opening H in a plan view. The height L22 of the first convex portion Dp1 is set taking into consideration that the conductive member 13 has a thickness extending between the two vias 16 on the wiring pad 18.

The second protrusion Dp2 is formed to a height L23 that protrudes by the thickness of the wiring such as the wiring pad 18. The second protrusion Dp2 has a convex pattern on the surface covered with the first covering layer 12 that is opposite to the pattern that protrudes from the base material 11 due to the first wiring layer 17 such as the wiring pad 18 formed on the base material 11.
By performing press processing using a mold having such a protrusion Dp, the binder resin contained in the conductive member 13 can be pushed out and removed, and an appropriate pressure can be applied to the wiring board 20, the adhesive layer 30, and the light-emitting module 10.
11A and 11B, the wiring board 20 and the light emitting module 10 are properly connected to each other by the adhesive layer 30, and the connection reliability is further improved.

Next, another embodiment of the method for manufacturing a surface-emitting light source will be described with reference to Fig. 12 and Fig. 13A to Fig. 14D. Note that the same reference numerals are used for the steps already described, and the description will be omitted as appropriate. In addition, the wiring board 20 will be described as having a configuration including the second wiring layer 14 and the second covering layer 15, but the second wiring layer 14 and the second covering layer 15 may not be formed.
In the manufacturing method of the surface-emitting light source, as shown in FIG. 12, the steps include a wiring substrate preparation step S11a, a through hole formation step S12, a via formation step S13, a filling step S14, a first coating layer formation step S14A, a press processing step S15, and a protective member formation step S16, which are performed in this order.

The difference from the manufacturing method shown in FIG. 7 is that the first covering layer is not formed in the wiring board preparation step S11a, but is formed after the filling step S14.
In the wiring board preparation step S11a, a first wiring layer 17 is formed on the back surface of the base material 11. Note that in the wiring board preparation step S11a, the first covering layer 12 that covers the first wiring layer 17 is not formed at this timing. Also, the wiring board 20 prepared in the wiring board preparation step S11a has the second wiring layer 14 and the second covering layer 15 formed on the front surface side of the base material 11.
Then, a through hole forming step S<b>12 is performed to temporarily connect the wiring board 20 to the adhesive layer 30 , which is an adhesive layer, and to form a through hole 160 in the wiring pad 18 of the first wiring layer 17 .
Next, a via forming step S13 is performed, and then a filling step S 14 is performed. Note that by performing the filling step S14 before the first covering layer forming step S14A, the connection between the metal members, that is, the conductive member 13 and the wiring pad 18, becomes stronger.

In the first coating layer forming process S14A, the first coating layer 12 is formed on top of the conductive member 13 formed in the via 16 and on the wiring pad 18. The first coating layer 12 has an opening H5 on the wiring pad 18, the opening area of which is smaller than the area of the wiring pad 18. The shape of the opening H5 in a plan view is the same as the opening H2 described above. The opening H5 in the first coating layer 12 is different from the configuration already described in that the first coating layer 12 is disposed between the adjacent first rectangular opening H51 and second rectangular opening H52 so as to be on top of the conductive member 13.

The first covering layer forming step S14A is followed by a pressing step S15. In the pressing step S15, pressing is performed by the method shown in any one of Figs. 8E, 11A, and 11B. The conductive member 13 filled in the via 16 is covered by the first covering layer 12 in a state in which the height above the wiring pad 18 is reduced by pressing and the thickness of the conductive member 13 is smaller than that of the first covering layer 12. The first covering layer 12 is pressed with the opening H5 formed on the wiring pad 18, so that the volatile component of the conductive member 13 is released from the opening H5 and the opening H5 is formed on the wiring pad, so that the set pressure can be appropriately applied to the wiring board 20 and the adhesive layer 30, and the via resistance can be reduced.
Next, a protective member forming step S16 is performed to form a protective member 19 made of insulating resin in the opening H5.

In the method of manufacturing the surface-emitting light source shown in Fig. 12 and Fig. 13A to Fig. 13D, the first covering layer 12 may be provided on the first wiring layer 17 so as to form an opening H6, as shown in Fig. 14A to Fig. 14D. The shape of the opening H6 in a plan view is the same as the opening H3 described above. In the configuration shown in Fig. 14A to Fig. 14D, the same steps as those described above are performed, except that the shape of the opening H6 in the first covering layer 12 is different.
The surface-emitting light source 100 formed by the steps of this manufacturing method has high connection reliability, similar to that described above.

15A to 15E are plan views showing modified examples of the filling state of the conductive member in Fig. 4 and Fig. 9A to Fig. 9D, respectively. Fig. 15F is a plan view showing modified examples of the opening in the covering layer and the filling state of the conductive member. Fig. 16A is a cross-sectional view taken along line XVIA-XVIA in Fig. 15A, and Fig. 16B is a cross-sectional view taken along line XVIB-XVIB in Fig. 15A.
15A to 15F and 16A to 16B, the state of the conductive member 13 filled in the vias 16 of the wiring pad 18 may be such that, in a plurality of vias 16, the conductive member 13 is independently filled in one via 16 as conductive members 13A and 13B. The conductive members 13A and 13B are made of the same material as the conductive member 13 already described. Note that the components already described are denoted by the same reference numerals and description thereof will be omitted.
The surface-emitting light source 100 includes a wiring board 20 and a plurality of light-emitting modules 10 via an adhesive layer 30, and the wiring board 20 includes a base material 11, a wiring layer (first wiring layer) 17 formed on the back surface of the base material 11 opposite to the light-emitting modules 10, a conductive member 13 filled in vias 16 formed for each wiring pad 18 that is a part of the wiring layer 17, and a covering layer (first covering layer) 12 that covers the wiring layer 17 and has an opening H formed therein to expose a part of the wiring pad 18. Furthermore, the light-emitting module 10 is formed by aligning a plurality of light-emitting devices 1, and the opening H is formed on the wiring pad 18 with an opening area smaller than the area of the wiring pad 18.

For example, as shown in FIG. 15A, when two vias 16, which have already been described mainly with reference to FIG. 4, are formed in the wiring pad 18, and there is one opening H whose opening area is smaller than the area of the wiring pad 18, the conductive members 13A and 13B may be formed to fill each of the vias 16. The conductive members 13A and 13B are provided so as to be lower than the height of the first coating layer 12 in the inner part of the opening H. The conductive members 13A and 13B are installed around the vias 16 so as to contact a part of the surface of the wiring pad 18 in a direction different from the direction in which the two vias 16 are linearly connected (the left-right direction in FIG. 15A). In this way, in order to fill each of the vias 16 with the conductive members 13A and 13B independently, the conductive members 13 can be screen-printed through a mask, for example.

9A, the conductive member 13 may be filled independently into each of the vias 16 in the first rectangular opening H11 and the second rectangular opening H12. The conductive member 13 is more easily partitioned because a part of the first coating layer 12 between the first rectangular opening H11 and the second rectangular opening H12 becomes a step and the first rectangular openings H11 and H12 are formed for each via 16.
15C, in the configuration of FIG. 9B already described, the conductive member 13 may be filled independently into each of the vias 16 in the first rectangular opening H21 and the second rectangular opening H22. The conductive member 13 is likely to be partitioned by a step formed by a part of the first coating layer 12 between the first rectangular opening H21 and the second rectangular opening H22.

15D, in the configuration of FIG. 9C already described, the conductive member 13 may be independently filled in each of the vias 16 in the first rectangular opening H31, the second rectangular opening H32, the third rectangular opening H33, and the fourth rectangular opening H34. Here, one conductive member 13 is filled in one via 16 so as to span the first rectangular opening 31 and the second rectangular opening 32. The other conductive member 13 is filled in one via 16 so as to span the third rectangular opening H33 and the fourth rectangular opening H34.
Also, as shown in FIG. 15E, in the configuration of FIG. 9D already described, the conductive material 13 may be filled independently into one via 16 and the other via 16 in the inner portion of the opening H4.
In addition, as shown in Fig. 16B, the cross-sectional shape of the conductive members 13A and 13B shown in Fig. 15A is formed in a curved convex shape toward the opposite side of the light-emitting module 10 with the parts exposed from the wiring pad 18 spaced apart from each other in the direction in which the vias 16 continue on a straight line (the vertical direction in Fig. 15A). In addition, the cross-sectional shape of the conductive members 13A and 13B from the wiring pad 18 in the direction perpendicular to the direction in which the vias 16 continue on a straight line (the horizontal direction in Fig. 15A) is formed in a flattened arc shape with the parts of the vias 16 in contact with the pad electrodes joined together, as shown in Fig. 16A. In addition, Figs. 16A and 16B showing the cross-sectional shape of Fig. 15A are almost the same as Figs. 15B to 15E.

Furthermore, as shown in FIG. 15F, the opening H7 formed in the first coating layer 12 has a first rectangular opening H71, a second rectangular opening H72, and a third rectangular opening H73. The opening H7 is formed on the wiring pad 18 so that the total opening area is smaller than the area of the wiring pad 18. The first rectangular opening 51, the second rectangular opening H72, and the third rectangular opening H73 are aligned in a straight line, and the second rectangular opening H72 located in the center is formed so that its opening area is larger than the first rectangular opening H71 and the third rectangular opening 73 located in the vertical direction in FIG. 15F. One of the vias 16 is formed to span the first rectangular opening H71 and the second rectangular opening 72, and the other is formed to span the second rectangular opening H72 and the third rectangular opening H73.

Moreover, one conductive member 13A is filled in one via 16 and is formed to extend over the second rectangular opening H72 and the third rectangular opening H73. Furthermore, the other conductive member 13B is filled in the other via 16 and is formed to extend over the first rectangular opening H71 and the second rectangular opening H72. Then, one conductive member 13A and the other conductive member 13B are formed in the second rectangular opening H72 with a space between them. In this way, the parts exposed at the top of the conductive members 13A and 13B are formed in a vertically elongated shape in the vertical direction of FIG. 15F along the direction from the first rectangular opening H71 to the third rectangular opening H73 aligned in a straight line (the vertical direction of FIG. 15F). When the conductive members 13A and 13B are filled in the via 16, for example, they can be also performed by moving a squeegee through a screen printing mask in the vertical direction of FIG. 15F.
15F has substantially the same shape as the conductive members 13A and 13B shown in FIG. 15A, except that the orientation of the cross-sectional shape of the portion exposed from the wiring pad 18 differs from that of the conductive members 13A and 13B shown in FIG. 15A.
15A to 15F, electrical connection is ensured at the contact portion between the wiring pad 18 and the conductive members 13A and 13B. Therefore, when the first covering layer 12 is configured to overlap the periphery of the opening of the via 16, it is preferable that the ratio of the first covering layer 12 overlapping with the periphery of the opening of the via 16 is 30% or less of the entire periphery of the opening of the via 16. As long as the wiring pad 18 and the conductive member 13 have contact portions and are electrically connected, the shape of the conductive member 13 in a plan view is not particularly limited.

As described above, in the surface-emitting light source 100 and its manufacturing method, the openings H, H1 to H7 of the first covering layer 12 are formed on the wiring pads 18, so that there are almost no areas where pressure is difficult to transmit during press processing, and there is no risk of insufficient adhesion. Also, in the manufacturing method, by pressing the insides of the openings H, H1 to H7 with the sheet Pc1 or the protruding portion Dp of the mold, excess binder resin contained in the conductive member 13 can be removed, and the via resistance can be reduced.
Although the openings H and H1 to H7 have been described as being mainly rectangular, they may be of other shapes such as round holes, etc. Furthermore, the number of vias 16 formed in the wiring pad 18 and the shape of the via holes are not limited.
Furthermore, in the surface-emitting light source 100, a wiring board 20 in which the first wiring layer 17 and the first covering layer 12 are formed only on the back surface of the base material 11 as shown in FIG.
In the surface-emitting light source and the method for manufacturing the surface-emitting light source, the timing for forming the first covering layer 17 may be either the step of Fig. 7 or the step of Fig. 12. The shape and size of the opening in the first covering layer 17 are not limited as long as it has an opening area smaller than the area of the wiring pad on the wiring pad and is formed so as to overlap at least a part of the via.
In other words, it is of course possible to make various modifications within the scope of the claims in the surface emitting light source. Also, in the method of manufacturing the surface light source device, it is of course possible to include other processes between each process or before or after the entire process.

REFERENCE SIGNS LIST 1 Light emitting device 2 Light emitting element 3 Light-transmitting member 4 Covering member 5 Element electrode 6 Wiring layer of light emitting module 7 Light guide plate 7a Optical function section 8 Light reflecting member 9 Insulating member (covering layer for wiring layer of light emitting module)
10 Light emitting module 11 Base material 12 First covering layer (covering layer)
13 Conductive member 14 Second wiring layer (wiring layer)
15 Second coating layer (coating layer)
16 Via 17 First wiring layer (wiring layer)
18 Wiring pad 18A Positive electrode side wiring pad 18B Negative electrode side wiring pad 18c Thin wire-shaped wiring 19 Protective member 20 Wiring board 30 Adhesive layer 100 Surface-emitting light source 160 Through hole Dp Convex portion Dp1 First convex portion Dp2 Second convex portion G01 Gap H, H1, H2, H3, H4, H5, H6, H7 Opening H11, H21, H31, H51, H61, H71 First rectangular opening H12, H22, H32, H52, H62, H72 Second rectangular opening H33, H63, H73 Third rectangular opening H34, H64 Fourth rectangular opening HL1, HL2, HL12, HL11 Heat plate Pc1 Sheet S11, S11a Wiring board preparation process S12 Through-hole forming process S13 Via forming process S14 Filling process S15 Pressing process S16 Protective member forming process SL 1 cell S14A First coating layer forming process h41, h42, h43, h44 Convex side portion

Claims (19)

The light emitting device includes a wiring board and a plurality of light emitting modules disposed via an adhesive layer;
the wiring board includes a base material, a wiring layer formed on a back surface of the base material opposite to the light emitting module, a conductive member filled across two or more of a plurality of vias formed for each wiring pad that is a part of the wiring layer, and a covering layer that covers the wiring layer and has an opening formed therein to expose a part of the wiring pad;
The light emitting module is formed by arranging a plurality of light emitting devices,
The opening is a surface-emitting light source formed on the wiring pad and has an opening area smaller than an area of the wiring pad. The surface-emitting light source according to claim 1, wherein each of the openings is formed to a size that exposes multiple vias formed in the wiring pad from the covering layer. The surface-emitting light source according to claim 1, wherein the opening is formed for each of the vias. The surface-emitting light source according to claim 1, wherein a plurality of the openings are formed adjacent to one of the vias, and a portion of the opening and a portion of the coating layer are formed adjacent to a portion of the periphery of the via. The surface-emitting light source according to any one of claims 1 to 4, wherein the opening is formed in a shape that is symmetrical with respect to the center of the via. The opening includes a first rectangular opening and a second rectangular opening,
a portion of the first rectangular opening is formed to overlap a portion of the vias on one side from a center of the vias, the portion extending across the vias;
a portion of the second rectangular opening is formed to overlap a portion of the via on the other side from the center of the via, the portion extending across the plurality of vias;
The surface-emitting light source according to claim 1 , wherein the first rectangular opening and the second rectangular opening are disposed adjacent to each other with the covering layer and a part of the via interposed therebetween. The surface-emitting light source according to claim 1, wherein the openings are formed such that a first rectangular opening and a second rectangular opening are adjacent to each other for one of the vias. The surface-emitting light source according to claim 7, wherein the via is located on one side offset from the center of the first rectangular opening, and the via is located on the other side offset from the center of the second rectangular opening, and the first rectangular opening and the second rectangular opening are formed adjacent to each other via the covering layer. the openings include a first rectangular opening, a second rectangular opening, a third rectangular opening, and a fourth rectangular opening, the first rectangular opening and the second rectangular opening being formed adjacent to one of the vias at a position where they partially overlap one of the vias, and the third rectangular opening and the fourth rectangular opening being formed adjacent to the other of the vias at a position where they partially overlap one of the vias,
2. The surface-emitting light source according to claim 1, wherein the first rectangular opening and the third rectangular opening are arranged adjacent to each other via the covering layer, and the second rectangular opening and the fourth rectangular opening are arranged adjacent to each other via the covering layer. The surface-emitting light source according to any one of claims 1 to 9, in which a protective member is provided to cover the conductive member. The surface-emitting light source according to any one of claims 1 to 10, wherein the wiring layer is provided on the surface of the substrate. The surface-emitting light source according to any one of claims 1 to 11, wherein the modulus of elasticity of the adhesive layer is lower than the modulus of elasticity of the base material. The surface-emitting light source according to any one of claims 1 to 12, wherein the elastic modulus of the substrate is 2 GPa or more and 5 GPa or less, and the elastic modulus of the adhesive layer is 100 MPa or more and 1 GPa or less. A method for manufacturing the surface emitting light source according to any one of claims 1 to 13, comprising the steps of:
a wiring board preparation process for preparing a wiring board including a base material, a wiring layer provided on a back surface of the base material, and a covering layer having a wiring pad that is a part of the wiring layer and covering the wiring layer so as to form an opening that is within the area of the wiring pad and exposes a part of the wiring pad;
a through hole forming step of providing an adhesive layer on a front surface side of the base material and forming a through hole in the wiring pad through the opening, the through hole penetrating the wiring board and the adhesive layer;
a via forming step of temporarily connecting a plurality of light emitting modules formed by aligning a plurality of light emitting devices on a front surface side of the base material via the adhesive layer to form the through hole as a bottomed via;
a filling step of filling the via with a conductive material;
and a press processing step of applying pressure and heat by press processing to bond the wiring board and the light emitting module via the adhesive layer. The method for manufacturing a surface-emitting light source according to claim 14 , wherein the press working step performs press working using a die via a sheet having the same shape as the opening in a plan view and a thickness equivalent to the depth of the opening. The method for manufacturing a surface emitting light source according to claim 14 , wherein the press working step is performed by using a die having convex portions that are opposite to the concave pattern from the surface of the base material to the surface of the coating layer. 17. The method for manufacturing a surface emitting light source according to claim 14, further comprising a protective member forming step of forming a protective member that covers the conductive member from one surface side of the wiring board after the press working step is performed. The method for manufacturing a surface-emitting light source according to claim 14 , wherein the filling step includes screen-printing the conductive member. The method for manufacturing a surface emitting light source according to claim 14 , wherein the wiring layer is further provided on a surface of the base material.

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