A light-emitting device with high luminance which has high uniformity in color and intensity can be provided. The light-emitting device includes a mounting substrate, a plurality of light-emitting elements disposed on the mounting substrate side by side, a wavelength conversion plate provided over the plurality of light-emitting elements and having a side surface, and a plurality of bumps disposed on the mounting substrate to abut against the side surface of the wavelength conversion plate, so as to determine a position of the wavelength conversion plate.

This application claims the priority benefit under 35 U.S.C. § 119 of Japanese Patent Application No. 2017-231601 filed on Dec. 1, 2017, which is hereby incorporated in its entirety by reference.

TECHNICAL FIELD

The presently disclosed subject matter relates to a light-emitting device including a light-emitting element.

BACKGROUND ART

Conventionally, a light-emitting device having a light-emitting element and a wavelength converter configured to convert the wavelength of light emitted from the light-emitting element has been known. For example, Japanese Patent Application Laid Open No. 2016-066680 discloses a light-emitting device including an LED element and a wavelength conversion layer.

The light-emitting device may include, for example, a semiconductor light-emitting element such as a light-emitting diode or a semiconductor laser as the light-emitting element. Further, in the case of the light-emitting device used for illumination, the light-emitting device may include a phosphor plate having a wavelength converter, for example, a phosphor, which can convert a wavelength from a light-emitting element to generate white light as illumination light. For example, the wavelength converter can receive light emitted from the light-emitting element and convert the wavelength of part of the light. The wavelength converter can generate outgoing light, for example, illumination light, which is output to the outside by mixing the wavelength-converted light and the light emitted from the light-emitting element.

Here, it is preferable that light having small color unevenness and intensity unevenness be emitted from the wavelength converter. For example, when the wavelength converter is disposed on the light-emitting element, it is preferable that the wavelength converter has a shape and a size so as to uniformly receive light emitted from the light-emitting element, and that the wavelength converter is securely fixed at a preferable position on the light-emitting element.

SUMMARY

The presently disclosed subject matter was devised in view of these and other problems and features in association with the conventional art. According to an aspect of the presently disclosed subject matter, a light-emitting device with high luminance in which a wavelength converter is securely fixed to a desired position on a light-emitting element and which has high uniformity in color and intensity can be provided.

According to another aspect of the presently disclosed subject matter, a light-emitting device can include: a mounting substrate; a plurality of light-emitting elements disposed on the mounting substrate side by side; a wavelength conversion plate provided over the plurality of light-emitting elements and having a side surface; and a plurality of bumps disposed on the mounting substrate to abut against the side surface of the wavelength conversion plate, so as to determine a position of the wavelength conversion plate.

In the light-emitting device with the above-described configuration, each of the bumps may be configured to include a bottom portion, an intermediate portion on the bottom portion, and a top portion on the intermediate portion, and the bottom portion may have a width smaller than those of the intermediate portion and the top portion. In this case, the intermediate portion of each of the bumps may have a width larger than that of the top portion, and each of the bumps may abut against the side surface of the wavelength conversion plate at the intermediate portion thereof.

Alternatively, in the light-emitting device with the above-described configuration, each of the bumps may be configured to include a first metal bump formed on the mounting substrate, and a second metal bump formed on the first metal bump and disposed on a side closer to the wavelength conversion plate than the first metal bump, and each of the bumps may abut against the side surface of the wavelength conversion plate at the second metal bump thereof.

Alternatively, in the light-emitting device with the aforementioned configuration, each of the bumps may be configured to include a first metal bump formed on the mounting substrate and having a stepped structure, and a second metal bump formed on the first metal bump and having a stepped structure and a width larger than that of the first metal bump, and each of the bumps may abut against the side surface of the wavelength conversion plate at the second metal bump thereof.

In the light-emitting device with the above-described configurations, the light-emitting elements may be arranged in a row, the bumps may be arranged in a direction in which the light-emitting elements are arranged, and the wavelength conversion plate may have a rectangular upper surface whose long side direction is the direction in which the light-emitting elements are arranged. In this configuration, the mounting substrate may include a pad terminal; each of the light-emitting elements may include a light-emitting portion disposed on a support substrate, and a pad electrode disposed on the support substrate to connect to the light-emitting portion and connected to the pad electrode of the mounting substrate by a bonding wire; the pad electrodes of the respective light-emitting elements may be aligned in the direction in which the light-emitting elements are arranged; and each of the bumps may be disposed on the pad electrode at a position closer to the light-emitting portion than the bonding wire.

Furthermore, the light-emitting device with the above-described configurations may further include: a base substrate to which the mounting substrate is fixed; a frame disposed on the base substrate to surround the mounting substrate; and a sealing portion configured to fill inside the frame to seal the light-emitting elements and expose the wavelength conversion plate.

According to still another aspect of the presently disclosed subject matter, a light-emitting device can include: a mounting substrate; a light-emitting element disposed on the mounting substrate; a wavelength conversion plate disposed on the light-emitting element and having a side surface; and a plurality of bumps disposed on the mounting substrate to abut against the side surface of the wavelength conversion plate, so as to determine a position of the wavelength conversion plate.

In the light emitting device with the above-described configuration, the side surface of the wavelength conversion plate may include side surfaces extending in mutually different directions, and the bumps may abut against the side surfaces correspondingly.

In the light emitting device with the above-described configurations, the mounting substrate may include a pad terminal; the light-emitting element may include a light-emitting portion disposed on a support substrate, and a pad electrode disposed on the support substrate to connect to the light-emitting portion and connected to the pad electrode of the mounting substrate by a bonding wire; and each of the bumps may be disposed on the support substrate at a position closer to the light-emitting portion than the bonding wire.

In the light emitting device with the above-described configuration, each of the bumps may be disposed on the support substrate in a region between the light-emitting portion and the pad electrode.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A description will now be made below to light-emitting devices of the presently disclosed subject matter with reference to the accompanying drawings in accordance with exemplary embodiments. In this description, the phrase “disposed/provided on” or the like phrase means to include cases where an object is directly disposed/provided on a corresponding object or indirectly disposed/provided above the corresponding object with another object interposed therebetween.

First Exemplary Embodiment

FIG. 1Ais a schematic top plan view of a light-emitting device10according to a first exemplary embodiment made in accordance with the principles of the presently disclosed subject matter.FIG. 1Bis a cross-sectional view of the light-emitting device10according to the first exemplary embodiment, taken along line V-V inFIG. 1A.FIG. 1Cis a cross-sectional view illustrating an enlarged part A surrounded by dashed line inFIG. 1B. The light-emitting device10will next be described with reference to these drawings.

First, as shown inFIGS. 1A and 1B, the light-emitting device10includes a base substrate (sometimes referred to as a first substrate or a wiring substrate)11on which wirings (first and second wirings) T1and T2are formed, and a plurality of light-emitting elements20mounted on the base substrate11.

In this exemplary embodiment, the light-emitting device10includes an insulating layer12formed on the base substrate11. The insulating layer12has an opening for exposing the upper surface of the base substrate11. The light-emitting device10includes a submount substrate13, which may be referred to as a second substrate or a mounting substrate, fixed inside the opening of the insulating layer12.

The light-emitting device10includes the plurality of light-emitting elements20mounted on the submount substrate13in a juxtaposed manner (side by side). In this exemplary embodiment, four light-emitting elements20are arranged in a row on the submount substrate13. Each of the light-emitting elements20is connected to wirings T1and T2formed on the base substrate11. The wirings T1and T2are connected to, for example, a connection terminal to the outside, for example, a driving circuit.

In this exemplary embodiment, the base substrate11may be made of a material having high thermal conductivity, for example, a metal material such as Cu. However, the base substrate11is not limited to the material, and may be made of, for example, an insulating material. When the base substrate11is made of an insulating material, the insulating layer12need not be provided, and the wirings T1and T2may be formed on the base substrate11. The submount substrate13may be made of a material having high thermal conductivity, for example, ceramics.

Here, each part of the light-emitting elements20will be described with reference toFIG. 1C. In this exemplary embodiment, each of the light-emitting elements20includes a p-type semiconductor layer (first semiconductor layer)22, an active layer23, and an n-type semiconductor layer (second semiconductor layer)24stacked on a support substrate (sometimes referred to as a third substrate)21. For example, each of the p-type semiconductor layer22, the active layer (light-emitting layer)23, and the n-type semiconductor layer24may be made of a nitride-based semiconductor.

In this exemplary embodiment, the p-type semiconductor layer22, the active layer23, and the n-type semiconductor layer24can constitute a light-emitting portion EM of the light-emitting element20. The upper surface of the n-type semiconductor layer24is an upper surface of each of the light-emitting elements20, and thus can function as a light extraction surface of each of the light-emitting elements20.

Each of the light-emitting elements20is connected to the wirings T1and T2on the base substrate11. In this exemplary embodiment, a p-side pad terminal (a first pad terminal) PP connected to the wiring T1of the base substrate11via a bonding wire BW is formed on the submount substrate13. In addition, on the submount substrate13, an n-side pad terminal (second pad terminal) PN connected to the wiring T2of the base substrate11via a bonding wire BW is formed.

Each of the light-emitting elements20has a p-side pad electrode P1formed on the support substrate21. A bump (connection bump) BP is formed on the p-side pad electrode P1. The p-side pad terminal PP and the bump BP are connected to each other via a bonding wire BW. In this exemplary embodiment, as shown inFIG. 1A, two bumps BP are formed on the p-side pad electrode P1of each of the light-emitting element20, and the p-side pad terminal PP and the bumps BP are connected by two bonding wires BW.

In this exemplary embodiment, the light-emitting elements20are connected to each other between the support substrate21and the submount substrate13.

Referring toFIG. 1A, in this exemplary embodiment, the light-emitting portion EM in each of the light-emitting elements20has a rectangular upper surface shape. Further, on the submount substrate13, the light-emitting portions EM are arranged so as to be aligned in one row, and the p-side pad electrodes P1are arranged so as to be aligned in one row along the arrangement direction of the light-emitting portions EM.

Next, as shown inFIG. 1A, the light-emitting device10includes a wavelength conversion plate30integrally formed over the respective light-emitting elements20. The wavelength conversion plate30is configured to perform wavelength conversion on the light emitted from each of the light-emitting elements20. The wavelength conversion plate30may include, for example, a plate-like member including phosphor particles and a binder, or a single crystal phosphor plate. In this exemplary embodiment, the wavelength conversion plate30has a rectangular upper surface shape in which the arrangement direction of the light-emitting elements20is the long side direction.

As shown inFIG. 1B, in this exemplary embodiment, one of the main surfaces of the wavelength conversion plate30is bonded to the upper surfaces of the light-emitting elements20, and the other main surface faces the outside. That is, the one main surface of the wavelength conversion plate30can function as a light receiving surface for the light emitted by the light-emitting elements20, and the other main surface thereof can function as a light extraction surface of the light-emitting device10.

The light-emitting device10includes bumps14that abut against the side surface of the wavelength conversion plate30to determine the position of the wavelength conversion plate30on each of the light-emitting elements20. In this exemplary embodiment, as shown inFIGS. 1A and 1B, the bumps14may be formed of cylindrical metal bumps (metal protrusions) provided on the p-side pad electrode P1of the support substrate21in each of the light-emitting elements20. Each of the bumps14is arranged in a row along the arrangement direction of the light-emitting elements20.

In other words, in this exemplary embodiment, the submount substrate13has the p-side pad terminals PP. Each of the light-emitting elements20includes the light-emitting portion EM disposed on the support substrate21, and the p-side pad electrode P1disposed on the support substrate21and connected to the light-emitting portion EM and connected to the p-side pad terminal PP of the submount substrate13by the bonding wire BW.

The respective p-side pad electrodes P1of the light-emitting elements20are aligned along the arrangement direction of the light-emitting element20, and each of the bumps14is disposed on the p-side pad electrode P1at a position closer to the light-emitting portion EM than the bonding wire BW.

Since the light-emitting device10has the bumps14, the position of the wavelength conversion plate30on the light-emitting elements20can be reliably determined. Accordingly, even when the wavelength conversion plate30is formed in a shape and size that substantially covers only the upper surfaces of the light-emitting portions EM, the high positioning accuracy allows the plate to be disposed without displacement.

If the bump14is not provided, the wavelength conversion plate may need to be prepared in a shape and size such that the wavelength conversion plate certainly covers the light-emitting portions EM, for example, not only the light-emitting portions EM but also the entire light-emitting elements20.

More specifically, when a wavelength conversion plate having a shape and size adapted only to the light-emitting portions EM on the light-emitting elements20is disposed without using the bump14, the upper surface of the light-emitting elements20may be partially exposed when viewed from the wavelength conversion plate side. In this case, there is a possibility that remarkable color unevenness will occur by emitting a large amount light whose wavelength is not converted from the exposed portion. When this issue is considered, a wavelength conversion plate having a relatively large size may have to be prepared.

Further, as a result of making the shape and size of the wavelength conversion plate sufficiently larger than the light-emitting portions EM, a region in which the light from the light-emitting portions EM does not directly enter, such as a region on the p-side pad electrode P1, is formed in the wavelength conversion plate. This causes unevenness in the intensity of light incident on the wavelength conversion plate, resulting in wavelength conversion unevenness, i.e., color unevenness.

However, in this exemplary embodiment, it is possible to accurately position the wavelength conversion plate30by the bumps14. Therefore, even if the wavelength conversion plate30is relatively small corresponding only to the light-emitting portions EM, the wavelength conversion plate30can be reliably fixed on the light-emitting elements20. Therefore, the wavelength conversion plate30may be prepared in a necessary shape and size without waste. Therefore, the light emitted from the light-emitting element20is received over almost the entire surface of the wavelength conversion plate30, and the light is extracted with a uniform color and intensity. In addition, the wavelength conversion plate30is miniaturized, resulting in a compact light-emitting device10.

In this exemplary embodiment, the bumps BP and the bonding wires BW for connection to the outside (in this exemplary embodiment, the p-side pad terminals PP on the submount substrate13) are formed on the p-side pad electrode P1. As shown inFIGS. 1A and 1B, the bumps14are provided on the p-side pad electrodes P1at respective positions closer to the wavelength conversion plate30than the bumps BP and the bonding wires BW. As a result, the wavelength conversion plate30is prevented from being brought into contact with the bonding wires BW, and damage to the bonding wires BW and connection failure resulting therefrom are prevented.

In addition, as shown inFIG. 1B, in this exemplary embodiment, the light-emitting device10includes a sealing portion15configured to seal the respective light-emitting elements20and the components, including the bonding wires BW and the p-side pad terminals PP and PN, on the submount substrate13and expose the upper surface of the wavelength conversion plate30. The sealing portion15may be made of a resin material, for example, a resin material having reflectivity with respect to light emitted from the light-emitting element20and the wavelength conversion plate30. For example, the sealing portion15may be made of a white resin. Note that illustration of the sealing portion15is omitted inFIG. 1A.

In this exemplary embodiment, a frame16is formed on the base substrate11to define a sealing region of the sealing portion15. The frame16is annularly formed on the base substrate11so as to surround the entire region of the light-emitting elements20and the submount substrate13. The frame16is made of a material such as ceramics, for example. The sealing portion15is formed to fill a region surrounded by the frame16on the base substrate11.

In other words, in this exemplary embodiment, the light-emitting device10includes the base substrate11to which the submount substrate13is fixed, the frame16disposed on the base substrate11so as to surround the submount substrate13, and the sealing portion15filled in the frame16to seal each of the light-emitting elements20and expose the wavelength conversion plate30.

By providing the frame16on the base substrate11, the position of the wavelength conversion plate30can be determined more reliably. For example, the sealing portion15can be formed by pouring a thermosetting resin into the frame16and then heating and curing the resin. By the thermosetting resin remaining in the frame16, unintended displacement of the wavelength conversion plate30is prevented, and the state in which the wavelength conversion plate30is reliably positioned is maintained even after the product is completed.

In addition, as in the light-emitting device10, since the light-emitting elements20are arranged in one row and the wavelength conversion plate30has a rectangular upper surface shape in which the arrangement direction of the light-emitting elements20is a long side direction, a line-shaped light distribution having high uniformity in color and intensity can be formed. For example, such a light-emitting device10is suitable as a lamp for a vehicle.

In this exemplary embodiment, the light-emitting device10has the base substrate11and the submount substrate13, and the light-emitting elements20are mounted on the submount substrate13. However, the light-emitting device10may not include the base substrate11.

The structure of the light-emitting element20described above is merely an example. For example, the light-emitting element20may have a structure in which the n-type semiconductor layer24, the active layer23, and the p-type semiconductor layer22are stacked on a growth substrate, and the growth substrate is mounted on the base substrate11or the submount substrate13. In addition, the light-emitting element20may not have the p-side pad electrode P1, but may be connected to the wiring T1by another connection means.

In this exemplary embodiment, a case where the bump14is formed of a cylindrical metal bump formed on the p-side pad electrode P1has been described, but the configuration of the bump14is only an example. For example, the bump14may be made of a resin material, and may have a prism shape, a pyramid shape, or other appropriate shapes.

In this exemplary embodiment, a case where the bump14is provided on each of the light-emitting elements20has been described, but the bump14may not be provided on each (all) of the light-emitting elements20. For example, the bumps14may be provided on the p-side pad electrodes P1of any two of the four light-emitting elements20.

In this exemplary embodiment, a case where the light-emitting device10has the sealing portion15and the frame16has been described, but the light-emitting device10may not have the sealing portion15and the frame16.

As described above, in this exemplary embodiment, the light-emitting device10includes the plurality of light-emitting elements20formed on the submount substrate (mounting substrate)13, the wavelength conversion plate30formed over the plurality of light-emitting elements20, and the bumps14configured to abut against the side surface of the wavelength conversion plate30to determine the position of the wavelength conversion plate30on the light-emitting element20. Accordingly, the wavelength conversion plate30can be securely fixed to a desired position on the light-emitting element20, and the light-emitting device10with high luminance and high uniformity in color and intensity can be provided.

Second Exemplary Embodiment

FIG. 2Ais a cross-sectional view of a light-emitting device10A according to a second exemplary embodiment.FIG. 2Bis an enlarged cross-sectional view illustrating a part AA surrounded by a dashed line inFIG. 2A. The light-emitting device10A will be described in detail with reference toFIGS. 2A and 2B. The light-emitting device10A has the same configuration as that of the light-emitting device10except for the configuration of a bump14A.

In this exemplary embodiment, as illustrated inFIG. 2B, the bump14A is configured to include a bottom portion41, an intermediate portion42, and a top portion43, and be formed on the p-side pad electrode P1as a metal bump having a substantially cylindrical shape as a whole. The intermediate portion42of the bump14A has a width larger than those of the bottom portion41and the top portion43in the direction parallel to the submount substrate13, i.e., a diameter in this exemplary embodiment. In the light-emitting device10A, the side surface of the wavelength conversion plate30abuts against the side surface of the intermediate portion42of the bump14A.

Also, as shown inFIG. 2B, the wavelength conversion plate30is bonded to the surface of the light-emitting portion EM (n-type semiconductor layer24) by an adhesive AD while a portion of its side is abutting against the bump14A. In addition, in this exemplary embodiment, part of the adhesive AD is disposed on the support substrate21so as to be in contact with a lower part of the side surface of the wavelength conversion plate30and embed the bump14A. Although not clearly shown in these drawings, the sealing portion15seals the light-emitting elements20, the bonding wires BW, and the like while being in contact with the upper surface of the adhesive AD.

Next, with reference toFIGS. 3A to 3C, a production process of the light-emitting device10A, in particular, a forming step of the bump14A and a bonding step of the wavelength conversion plate30to the light-emitting element20will be described. Each ofFIGS. 3A to 3Cis a cross-sectional view showing a part AA surrounded by a dashed line inFIG. 2Ain the production process of the light-emitting device10A.

First, a step of forming the bump14A (step A) will be described with reference toFIG. 3A. In this exemplary embodiment, the bump14A is a metal bump made of Au. The bump14A can be formed by using a bonding apparatus, for example, after a step of mounting the light-emitting element20on the submount substrate14, and during a step of connecting the p-side pad terminal PP on the submount substrate13and the p-side pad electrode P1on the support substrate21by wire bonding.

For example, the bump14A can be formed by stacking two Au bumps on a side closer to the light-emitting portion EM than the connection bump BP on the p-side pad electrode P1when the connection bump BP, such as inFIG. 1A, is formed. The bump14A can be stably formed by reducing the bump size in the first stage of the two-stage bump formation and increasing the bump size in the second stage. Further, by shifting the second-stage bump closer to the light-emitting portion EM than the first-stage bump, the bump14A can be stably formed.

Next, an adhesive AD is applied onto the light-emitting portion EM (step B). In this exemplary embodiment, as the adhesive AD, a viscous thermosetting resin is applied onto the surface of the n-type semiconductor layer24. At this time, as shown inFIG. 3A, the adhesive AD is preferably disposed only on the light-emitting portion EM.

Next,FIG. 3Bis a diagram illustrating a state in which the wavelength conversion plate30is provisionally disposed on the light-emitting element20. The wavelength conversion plate30is disposed on the light-emitting portion EM by using a conveying device, and is pressed against the adhesive AD (step C). As a result, the adhesive AD is brought into contact with the entire bottom surface of the wavelength conversion plate30, so that the wavelength conversion plate30is provisionally positioned on the light-emitting portion EM. At this time, the adhesive AD overflows from the light-emitting portion EM toward the bump14A on the support substrate21. In this exemplary embodiment, the entire bump14A is thus embedded in the adhesive AD.

Next,FIG. 3Cis a view illustrating a state in which the wavelength conversion plate30is made abut against the bump14A to be fixed. After the aforementioned step C, the wavelength conversion plate30is moved to the bump14A in a self-aligned manner to abut against the bump14A, thereby being positioned (step D). Specifically, the wavelength conversion plate30is disposed on the adhesive AD, so that the adhesive AD overflows toward the bump14A, whereby the wavelength conversion plate30is gradually moved (displaced) toward the bump14A. As a result, the side surface of the wavelength conversion plate30can abut against the bump14A, so that the position of the wavelength conversion plate30is determined.

Here, in this exemplary embodiment, only the side surface of the intermediate portion42of the bump14A can abut against (be brought into contact with) the wavelength conversion plate30. Therefore, the side surfaces of the bottom portion41and the top portion43of the bump14A are not in contact with the wavelength conversion plate30. By forming the bump14A with this configuration in this manner, the wavelength conversion plate30can stably abut against the bump14A, so that the position thereof is reliably determined.

Specifically, first, since the bottom portion41of the bump14A has a width smaller than that of the intermediate portion42, the adhesive AD stably moves toward the region between the wavelength conversion plate30and the bottom portion41of the bump14A when the wavelength conversion plate30is displaced. That is, the bottom portion41ensures the escape of the adhesive AD (moving path for the adhesive AD). Therefore, the intermediate portion42and the wavelength conversion plate30reliably abut against each other.

Similarly, since the intermediate portion42of the bump14A has a width larger than that of the top portion43, it is possible to secure the escape of the adhesive AD in the case where the adhesive AD is applied in an amount to bury the bump14A as in this exemplary embodiment, for example. Therefore, since the bump14A has the intermediate portion42, and the bottom portion41and the top portion43having a smaller width than that of the intermediate portion42, the wavelength conversion plate30surely abuts against the bump14A, so that the position of the wavelength conversion plate30is surely determined.

In this exemplary embodiment, a case where the bump14A is composed of the bottom portion41, the intermediate portion42, and the top portion43, and the bottom portion41and the top portion43each have a width smaller than that of the intermediate portion42has been described, but the configuration of the bump14A is not limited to this aspect as long as the bump14A has the bottom portion41with a width smaller than those of the intermediate portion42and the top portion43. For example, the top portion43of the bump14A may have a width larger than that of the intermediate portion42, and the top portion43may abut against the wavelength conversion plate30.

Thus, in this exemplary embodiment, the bump14A has the bottom portion41, the intermediate portion42provided on the bottom portion41, and the top portion43provided on the intermediate portion42, and the bottom portion41has a smaller width than the intermediate portion42and the top portion43. Therefore, the wavelength conversion plate30can be securely fixed to a desired position on the light-emitting element20, and thereby the light-emitting device10A with high luminance and high uniformity in color and intensity can be provided.

Third Exemplary Embodiment

FIG. 4Ais an enlarged cross-sectional view illustrating the vicinity of a bump14B in a light-emitting device10B according to a third exemplary embodiment in an enlarged manner. The light-emitting device10B has the same configuration as that of the light-emitting device10except for the configuration of the bump14B.

In this exemplary embodiment, the bump14B is formed of a metal bump having a two-stage structure. The bump14B is configured to include a lower bump (first metal bump)44formed on the p-side pad electrode P1(mounting substrate13) and an upper bump (second metal bump)45formed on the lower bump44on a side closer to the wavelength conversion plate30with respect to the lower bump44.

In this exemplary embodiment, as shown inFIG. 4A, the lower bump44has a stepped cylindrical shape whose upper portion is thinner than the bottom portion. Like the lower bump44, the upper bump45has a stepped cylindrical shape whose upper portion is thinner than the lower portion. The upper bump45is disposed such that the vertically extending central axis AX2of the cylindrical shape thereof is located closer to the light-emitting portion EM (wavelength conversion plate30) than the vertically extending central axis AX1of the cylindrical shape of the lower bump44. In this case after the formation of the upper bump45, the entire height should be higher than the EM height.

The bump14B can be formed, for example, by stacking two stepped Au bumps in two stages at different center positions, and corresponds to a case where the bump shape of the first stage (stepped shape) is maintained to a certain extent after stacking the Au bump in the second stage, which will be discussed later.

Therefore, in this exemplary embodiment, the bump14B has a substantially four-stepped structure, and has a cylindrical shape in which the upper portion with the step, or the upper bump45, is eccentric toward the light-emitting portion EM. In addition, the wavelength conversion plate30abuts against the side surface of the upper bump45(in this exemplary embodiment, the side surface on the bottom portion side (the side close to the lower bump44) of the upper bump45).

This exemplary embodiment corresponds to a configuration in consideration of a case where the side surface of the bump and the side surface of the wavelength conversion plate30do not surely abut against each other in two stages of metal bumps having the same size and the same center position. For example, in general, when a bump is to be formed in two stages, the bump in the first stage is deformed so as to slightly collapse at the time of forming the bump in the second stage. In this case, the height of the bump in the first stage is slightly reduced, and the width of the bump is slightly enlarged. Therefore, for example, when the upper bump45is formed with the same size and center position as the lower bump44, the position of the side surface of the first-stage bump or the lower bump44is shifted toward the light-emitting portion EM and at the same time the height thereof may be formed lower. As a result, the wavelength conversion plate30may ride over the lower bump44.

On the other hand, in this exemplary embodiment, the bump14B has the upper bump45, which is certainly higher than the light-emitting portion EM (and the adhesive AD). The upper bump45is also formed in an eccentric manner relative to the lower bump44so that its central axis AX2is disposed on the side closer to the wavelength conversion plate30than the central axis AX1of the lower bump44. Therefore, the wavelength conversion plate30surely abuts against the bump14B without riding on the bump14B, so that the wavelength conversion plate30can be surely positioned and bonded.

Although a case where the bump14B has a two-stage structure has been described in this exemplary embodiment, the configuration of the bump14B is not limited to this. In another aspect, the bump14B may a stacked structure of three or more layers as long as they are eccentric to each other. For example, an intermediate bump having a central axis disposed between those of the lower bump44and the upper bump45may be provided. The bump14B is not limited to a cylindrical shape, and may have, for example, a prism shape or a cone shape.

As described above, in this exemplary embodiment, the bump14B has the lower bump (first metal bump)44formed on the mounting substrate13, and the upper bump (second metal bump)45disposed on the lower bump44on a side closer to the wavelength conversion plate30with respect to the lower bump44. The bump14B is also configured to abut against the wavelength conversion plate30on the side surface of the upper bump45. Therefore, the wavelength conversion plate30is securely fixed to a desired position on the light-emitting element20, so that the light-emitting device10B having high luminance and high uniformity of color and intensity can be provided.

Fourth Exemplary Embodiment

FIG. 4Bis an enlarged cross-sectional view illustrating the vicinity of a bump14C in a light-emitting device10C according to a fourth exemplary embodiment in an enlarged manner. The light-emitting device10C has the same configuration as that of the light-emitting device10except for the configuration of the bump14C.

First, the bump14C has, for example, a two-stage structure similarly to the bump14B. On the other hand, in this exemplary embodiment, the bump14C is configured to include a lower bump (first metal bump)46formed on the p-side pad electrode P1(mounting substrate13) and an upper bump (second metal bump)47formed on the lower bump46and having a larger width than that of the lower bump44.

In this exemplary embodiment, as shown inFIG. 4B, the lower bump46has a stepped cylindrical shape in which the top portion is thinner than the bottom portion. The upper bump47has a stepped cylindrical shape whose upper portion is thinner than its bottom portion and whose overall width (diameter) thereof is larger than that of the lower bump46. In this exemplary embodiment, the bump14C can be formed, for example, by stacking two stepped Au bumps with the use amounts of Au different from each other, and corresponds to a case where the bump shape of the first stage (stepped shape) is maintained to a certain extent after stacking the Au bump in the second stage.

In this exemplary embodiment, the bump14C has a substantially four-stage structure, and when the side close to the mounting substrate13is referred to as the first stage, the third stage has a cylindrical shape having the largest diameter. In this state, the wavelength conversion plate30abuts against the side surface of the upper bump47of the bump14C (in this exemplary embodiment, the side surface on the bottom portion side (the side close to the lower bump46) of the upper bump47).

Similar to the bump14B, the bump14C is configured to include the upper bump47larger than the lower bump46in consideration of a case where the wavelength conversion plate30is not reliably positioned by means of a two-stage bump of the same size and center position or a case where the wavelength conversion plate30rides on the lower bump46. Therefore, the wavelength conversion plate30can be reliably positioned.

FIG. 4Billustrates a case where the upper bump47is arranged on the same central axis as the lower bump46. However, the upper bump47and the lower bump46may be arranged so that their center axes are different from each other, as shown inFIG. 4A, for example. Furthermore, the bump14C is not limited to a cylindrical shape, and may have, for example, a prism shape or a cone shape.

As described above, in this exemplary embodiment, the bump14C is configured to include the stepped lower bump (first metal bump)46formed on the mounting substrate13, and the stepped upper bump (second metal bump)47formed on the lower bump46and having a larger width than that of the lower bump46. The bump14C abuts against the wavelength conversion plate30on the side surface of the upper bump47. Therefore, the wavelength conversion plate30is securely fixed to a desired position on the light-emitting element20, and the light-emitting device10C having high luminance and high uniformity of color and intensity can be provided.

FIG. 5Ais a schematic top plan view of a light-emitting device50according to according to a fifth exemplary embodiment. The light-emitting device50has the same configuration as that of the light-emitting device10except that it includes only one light-emitting element20. The light-emitting device10includes the single light-emitting element20formed on the submount substrate13, a wavelength conversion plate30formed on the light-emitting element20, and a plurality of bumps51formed on the submount substrate13and configured to abut against the side surface of the wavelength conversion plate30to determine the position of the wavelength conversion plate30on the light-emitting element20.

Like the light-emitting device50, only one light-emitting element20to be mounted may be adopted. In this exemplary embodiment, two bumps51are provided for the single light-emitting element20. Thus, for example, when the columnar bumps51are used, the position of the wavelength conversion plate30is reliably determined by using two or more bumps51. As a result, the wavelength conversion plate30is reliably fixed to a desired position on the light-emitting element20, and the light-emitting device50with high luminance and high uniformity in color and intensity can be provided.

FIG. 5Bis a schematic top view of a light-emitting device50A according to a modified example of the fifth exemplary embodiment. The light-emitting device50A has the same configuration as that of the light-emitting device50except for the configuration of the light-emitting element20A and the wavelength conversion plate30A as well as the configuration of the bump51A. In the present modified example, the light-emitting element20A has a light-emitting portion EM1having a rectangular upper surface from which a corner is removed. The wavelength conversion plate30A also has a rectangular upper surface shape from which a corner is removed in accordance with the upper surface shape of the light-emitting portion EM1.

The light-emitting element20A has a rectangular p-side pad electrode P1arranged at the removed corner. In the present modified example, one connection bump BP to which one bonding wire BW is connected is disposed on and connected to the p-side pad electrode P1.

Further, the light-emitting device50A is configured to include two bumps51A configured to two-dimensionally determine the position of the wavelength conversion plate30A at the removed corner position. In the light-emitting device50described above, the two bumps51abut against one side surface of the wavelength conversion plate30, thereby determining the position of the wavelength conversion plate30in the direction perpendicular to the side surface.

On the other hand, specifically in the present modified example, one of the two bumps51A abuts against one side surface of the wavelength conversion plate30A along one direction in a top view at the removed corner position. The other bump51A abuts against another side surface of the wavelength conversion plate30A along a direction different from the one direction, that is, a direction perpendicular to the one direction at the removed corner position.

Therefore, the bumps51A can two-dimensionally determine the position of the wavelength conversion plate30A on the light-emitting element20A within the plane of the light-emitting portion EM. Thus, for example, when the wavelength conversion plate30A is provisionally disposed on the adhesive, only the distance in the height direction between the wavelength conversion plate30A and the light-emitting portion EM, i.e., the gap between the wavelength conversion plate30A and the light-emitting element20, needs to be accurately controlled. Therefore, the wavelength conversion plate30A is reliably fixed to a desired position on the light-emitting element20A, so that the light-emitting device50A with high luminance and high uniformity of color and intensity can be provided.

Sixth Exemplary Embodiment

FIG. 6Ais a schematic top plan view of a light-emitting device60according to a sixth exemplary embodiment.FIG. 6Bis a cross-sectional view of the light-emitting device60according to the sixth exemplary embodiment taken along line W-W inFIG. 6A. The light-emitting device60has the same configuration as that of the light-emitting device50except that it has bumps61formed in a region between the light emitting unit EM and the p-side pad electrode P1.

As shown inFIGS. 6A and 6B, in the light-emitting device60, the bumps61are formed in the region between the light-emitting portion EM and the p-type pad electrode P1on the support substrate21. In this exemplary embodiment, the bump61is made of an insulating material, for example, is a resin bump made of a resin material.

For example, when the bump51is formed of a conductive material as in the light-emitting device50according to the fifth embodiment, it is preferable to dispose the bumps51at a certain distance in consideration of the fact that an electrical connection may be formed between the light-emitting element20and the bump51. On the other hand, when the bumps61are formed of an insulating material, as shown inFIG. 6B, the bumps61can be disposed closer to the light-emitting portion EM, that is, the p-type semiconductor layer21, the active layer23, and the n-type semiconductor layer24.

Therefore, as shown inFIG. 6A, the wavelength conversion plate30B can be formed to have substantially the same size as that of the light-emitting portion EM. Therefore, it is possible to provide a high-quality light-emitting device60in which color unevenness and intensity unevenness are greatly suppressed.

The above-described embodiments can be selected and combined with one another. For example, the light-emitting device10may include the bumps61used in the light-emitting device60. In another aspect, the light-emitting device60may include a plurality of light-emitting elements20.

It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter cover the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related art references described above are hereby incorporated in their entirety by reference.