Light-emitting device and method for its manufacture

Abstract

Light-emitting device (1) comprising: a substrate (10), a plurality of light-emitting elements (30) mounted on the substrate (10), a first resin layer (50) which integrally seals the plurality of light-emitting elements (30) and which contains a first yellow phosphor (51) which is excited by light from the plurality of light-emitting elements (30), wherein the closer a portion in which the first yellow phosphor is contained from an upper end far from the substrate (10) to a lower end close to the substrate (10) (51), the higher the concentration of the first yellow phosphor (51), and a second resin layer (60) provided on an upper side of the first resin layer (50) and containing a second yellow phosphor (61) excited by light from the plurality of light-emitting elements (30) and which is the same phosphor as the first yellow phosphor (51) in a uniform concentration, wherein the second yellow phosphor (61) is uniformly dispersed in the second resin layer (60) at a concentration lower than the concentration of the first yellow phosphor (51) at the lower end of the first resin layer (50).

Description

Technical area

[0001] The present invention relates to a light-emitting device and a method for manufacturing the same. State of the art

[0002] A chip-on-board (COB) light-emitting device in which light-emitting elements such as light-emitting diode (LED) elements are mounted on a general-purpose substrate such as a ceramic substrate or a metal substrate is known. In such a light-emitting device, by sealing the LED elements with a light-transmitting resin containing a phosphor, and by mixing the light from the LED elements and the light obtained by exciting the phosphor with the light from the LED elements, white light or the like can be obtained depending on the intended use.

[0003] For such a light-emitting device, in order to improve heat dissipation and suppress chromaticity deviations, a manufacturing method is known in which the LED elements are sealed with an uncured resin in which a phosphor is dispersed, into which the phosphor is precipitated (set), and then the resin is cured. For example, Patent Literature 1 discloses a light-emitting diode comprising an LED chip on a support medium and a coating unit containing a phosphor that absorbs at least a portion of the light emission from the LED chip to perform wavelength conversion and emit light, and is formed on the LED chip and the support medium differently from the LED chip. The coating unit is formed by dispersing the phosphor in the gas phase or the liquid phase and depositing the phosphor.

[0004] Patent Literature 2 discloses a light-emitting device in which an LED chip has been sealed on a substrate with a light-transmitting resin not containing a phosphor, and a resin layer containing a phosphor is formed thereon to have a uniform thickness, and accordingly, color unevenness is unlikely to occur compared with the case where the phosphor is dispersed in the light-transmitting resin.

[0005] US 2015 / 340547 A1 discloses a method for manufacturing a light-emitting device, which comprises forming a first phosphor layer including a first phosphor based on KSF or quantum dots on a light-emitting element by a method other than sputtering, and forming a second phosphor layer including a second phosphor different from the first phosphor on the first phosphor layer by sputtering.

[0006] JP 2007 / 042687 A discloses a light-emitting diode device comprising a light-emitting diode chip that emits blue color light, a red phosphor layer, and a yellow phosphor layer. The red light-emitting phosphor layer is formed by dispersing and depositing a red light-emitting phosphor that emits red light when excited by blue light in a resin. A high-concentration layer and a low-density layer of the red light-emitting phosphor are formed in the red light-emitting phosphor layer, with the high-concentration layer being disposed on the light-emitting diode chip side. The yellow light-emitting phosphor layer is formed by dispersing a yellow light-emitting phosphor that emits yellow light when excited by light from the red light-emitting phosphor layer in a resin.The yellow light emitting phosphor layer is arranged on the side of the red light emitting phosphor layer. List of citationsPatent literature Patent Literature 1: Japanese Unexamined Publication (Kokai) JP H11 - 040858 A Patent Literature 2: Japanese Unexamined Publication (Kokai) JP 2003 - 101 074 A Summary of the invention

[0007] When a light-emitting element is sealed with an uncured resin in which a phosphor is dispersed and the phosphor is precipitated, flow occurs in the resin during the process of reducing the viscosity of the resin, and the phosphor also flows. In particular, when a plurality of light-emitting elements are mounted on a single substrate, the flow of the resin may vary depending on the location, and thus, fluctuations in the precipitation state (concentration) of the phosphor are likely to occur.When a plurality of light-emitting elements are mounted on a single substrate, as compared to when a single light-emitting element is mounted on a single substrate, fluctuations in the concentration of the phosphor among the light-emitting elements are caused, and this leads to significant fluctuations (color unevenness) in the light emission.

[0008] An object of the present invention is to provide a light-emitting device and a method for manufacturing the same, which avoid significant color unevenness during light emission even when there are fluctuations in the concentration of the phosphor precipitated in the resin used to seal the light-emitting elements between the light-emitting elements.

[0009] A light-emitting device is provided which includes a substrate, a plurality of light-emitting elements mounted on the substrate, a first resin layer which integrally seals the plurality of light-emitting elements and which contains a first yellow phosphor which is excited by light from the plurality of light-emitting elements, wherein the closer a portion in which the first yellow phosphor is contained is to a lower end near the substrate from an upper end far from the substrate, the higher the concentration of the first yellow phosphor, and a second resin layer which is provided on an upper side of the first resin layer and which contains a second yellow phosphor which is excited by the light from the plurality of light-emitting elements and which is the same phosphor as the first yellow phosphor in a uniform concentration, wherein the second,yellow phosphor is uniformly dispersed in the second resin layer at a concentration lower than the concentration of the first yellow phosphor at the lower end of the first resin layer.

[0010] Preferably, the concentration of the second yellow phosphor in the second resin layer is higher than the concentration of the first yellow phosphor at the upper end of the first resin layer.

[0011] Preferably, in the above-mentioned light-emitting device, the upper end of the first resin layer is a transparent resin layer which does not contain the first yellow phosphor.

[0012] Furthermore, a method for manufacturing a light-emitting device is provided, comprising the steps of: a step of mounting a plurality of light-emitting elements on a substrate, wherein the plurality of light-emitting elements are integrally sealed with an uncured resin containing a first yellow phosphor excited by the plurality of light-emitting elements, thereby forming a first resin layer, a step of precipitating the first yellow phosphor on one side of the substrate, curing the first resin layer, and a step of providing a second resin layer on an upper side of the first resin layer, wherein the second resin layer contains a second yellow phosphor excited by the light from the plurality of light-emitting elements and is the same phosphor as the first yellow phosphor,in a uniform concentration, wherein the second yellow phosphor is uniformly dispersed in the second resin layer in a concentration lower than the concentration of the first yellow phosphor at the lower end of the first resin layer.

[0013] According to the above-mentioned light-emitting device and the method for manufacturing the same, even if there are variations among the light-emitting elements in the concentration of the phosphor precipitated in the resin for sealing the light-emitting elements, significant unevenness of color during light emission is avoided. Short description of the drawings The Fig. 1 is a perspective view of a light-emitting device 1. The Fig. 2 is a cross-sectional view taken along a line II-II of the Fig. 1. The Fig. 3 is a perspective view illustrating the arrangements of the circuit substrate 20 and the LED elements 30. The Fig. 4 is a cross-sectional view taken along a line IV-IV of the Fig. 3. The Fig. 5(A) to 5(D) are drawings showing examples of the concentration distributions of the phosphors in the deposition phosphor layer 50 and the dispersion phosphor layer 60. The Fig. 6 is a flowchart illustrating an example of the manufacturing processes of the light-emitting device 1. The Fig. 7 is a perspective view of another light-emitting device 2. The Fig. 8 is a cross-sectional view taken along a line VIII-VIII of the Fig. 7. Description of the embodiments

[0014] A light-emitting device and a method for manufacturing the same will be explained in detail below with reference to the accompanying drawings. However, it should be noted that the present invention is not limited to the drawings or the embodiments described below.

[0015] The Fig. 1 is a perspective view of a light-emitting device 1. The Fig. 2 is a cross-sectional view taken along a line II-II of the Fig. 1. The light-emitting device 1 includes LED elements as the light-emitting elements and is used, for example, as LED light source devices for various illuminations. The light-emitting device 1 includes, as main components, a mounted substrate 10, a circuit substrate 20, LED elements 30, a resin frame 40, a deposition phosphor layer 50, and a dispersed phosphor layer 60.

[0016] As an example, the attached substrate 10 is a square metal substrate and has a circular attachment area 11 at a center of its upper surface (see the Fig. 3, which will be described later) to which the LED elements 30 are attached. The attached substrate 10 functions as a heat radiation substrate that radiates the heat generated by the LED elements 30 and the particles of the phosphor described later, and thus, it is composed, for example, of aluminum, which has excellent heat tolerance and heat dissipation. However, the material of the attached substrate 10 may also be composed of other metals, such as copper, as long as the material has excellent heat tolerance and heat dissipation.

[0017] The Fig. 3 is a perspective view illustrating the arrangements of the circuit substrate 20 and the LED elements 30. The Fig. 4 is a cross-sectional view taken along a line IV-IV of the Fig. 3.

[0018] As an example, the circuit substrate 20 has the same square shape as the attached substrate 10 and has a circular opening 21 at its center. The lower surface of the circuit substrate 20 is adhered and fixed to the circuit substrate 20, for example, via an adhesive sheet. A conductive pattern 23A is formed on one side of the upper surface of the circuit substrate 20, and a conductive pattern 23B is formed on the other side to surround the opening 21. A connection electrode 24A is formed at one diagonal corner on the upper surface of the circuit substrate 20, and a connection electrode 24B is formed at the other diagonal corner, respectively.One of the connecting electrodes 24A and 24B is an anode electrode and the other is a cathode electrode, and these electrodes are connected to an external power source to receive a voltage so that the light-emitting device 1 emits light.

[0019] The LED elements 30 are an example of the light-emitting elements, and for example, the LED elements are gallium nitride-based compound semiconductors that emit light of wavelengths ranging from the ultraviolet region to the blue region. Hereinafter, it is assumed that the LED elements 30 are blue LEDs that emit blue light with, for example, the light emission wavelength band of approximately 450 to 460 nm. However, the LED elements 30 may be elements that emit light with other wavelengths, such as violet light or ultraviolet light. In the light-emitting device 1, a plurality of LED elements 30 are arranged and mounted in a grid-like arrangement on the mounting region 11 of the mounted substrate 10, which is exposed in the opening 21 of the circuit substrate 20. Fig. 3 illustrates a case where, specifically, twenty-one LED elements 30 are mounted. The lower surfaces of the LED elements 30 are attached to the upper surface of the mounted substrate 10 via, for example, a transparent insulating adhesive.

[0020] Each LED element 30 has a pair of element electrodes on its upper surface, and as shown in the Fig. 2 and the Fig. 4, the element electrodes of adjacent LED elements 30 are electrically connected to each other via a connecting wire 31 (hereinafter simply referred to as a wire 31). The wires 31 from the LED elements 30 located on the outer peripheral side of the opening 21 are connected to the conductive pattern 23A or the conductive pattern 23B of the circuit substrate 20. This supplies a current to each LED element 30 via the wires 31.

[0021] The resin frame 40 is a circular frame formed of, for example, a white resin in accordance with the size of the opening 21 of the circuit substrate 20, and is attached at a position overlapping with the conductive patterns 23A and 23B formed to enclose the opening 21 of the upper surface of the circuit substrate 20. The resin frame 40 is a dam material for preventing the resin of the deposition phosphor layer 50 and the dispersed phosphor layer 60 from leaking out, and causes the light emitted laterally from the LED elements 30 to be reflected toward the upper surface of the light-emitting device 1 (the opposite side of the attached substrate 10 as viewed from the LED elements 30).

[0022] The deposition phosphor layer 50 is an example of the first resin layer and is formed of a transmissive resin containing a phosphor 51, which is a first phosphor. The deposition phosphor layer 50 fills, as shown in the Fig. 2, the deposition phosphor layer 50 forms a space surrounded by the resin frame 40 and is located on the attached substrate 10 up to a position higher than the upper ends of the wires 31, and integrally covers and protects (seals) the LED elements 30 and the wires 31. For the deposition phosphor layer 50, for example, a colorless and transparent thermosetting resin such as an epoxy resin or a silicone resin is used.

[0023] The phosphor 51 is a yellow phosphor such as yttrium aluminum garnet (YAG), and the particles thereof are deposited in the lower part of the deposition phosphor layer 50. In other words, the deposition phosphor layer 50 contains the phosphor 51 excited by the light from the LED elements 30, and the closer a portion containing the first phosphor 51 is to a lower end near the substrate 10 from an upper end far from the substrate 10, the higher the concentration of the first phosphor 51. In the Fig. 2, the precipitation of the particles of the phosphor 51 in the deposition phosphor layer 50 is represented by the pattern of light and shadow. As in the Fig. 2, the phosphor 51 precipitates not only on the upper surface of the attached substrate 10, but also on the upper surfaces of the LED elements 30.

[0024] The light-emitting device 1 emits white light obtained by mixing the blue light from the LED elements 30 with the yellow light obtained by exciting the phosphor 51 in the deposition phosphor layer 50 with the blue light. In the light-emitting device 1, since the LED elements 30 are directly mounted on the mounted substrate 10, which has high heat dissipation, and the phosphor 51 precipitates in the position close to the deposition phosphor layer 50 and the mounted substrate 10, the heat generated by the LED elements 30 and the phosphor 51 can be easily released to an outside of the device via the mounted substrate 10. Accordingly, a decrease in the light emission intensity of the LED elements 30 due to the heat can be prevented, and thus, this is beneficial in terms of improving the light emission intensity.

[0025] The dispersed phosphor layer 60 is an example of the second resin layer. It is formed of a transmissive resin containing a phosphor 61, which is a second phosphor, and is provided on the deposition phosphor layer 50. A colorless and transparent resin such as an epoxy resin or a silicone resin is also used for the dispersed phosphor layer 60. The materials of the dispersed phosphor layer 60 may be the same as or different from those of the deposition phosphor layer 50. Another transparent resin layer may be provided between the deposition phosphor layer 50 and the dispersed phosphor layer 60.

[0026] The phosphor 61, for example, is a yellow phosphor, which is the same as the phosphor 51. The dispersed phosphor layer 60 contains the phosphor 61 excited by the light from the LED elements 30 at a uniform concentration. In other words, the particles of the phosphor 61 in the dispersed phosphor layer 60 are uniformly dispersed regardless of the position in the horizontal direction and the vertical direction, unlike the phosphor 51 in the deposition phosphor layer 50. In the dispersed phosphor layer 60, the blue light from the LED elements 30 and the yellow light obtained by exciting the phosphor 61 with the blue light are mixed, and accordingly, white light is generated.

[0027] In the light-emitting device 1, the dispersive phosphor layer 60 in which the phosphor 61 is uniformly dispersed is provided on the deposition phosphor layer 50, and thus, the blue light from the deposition phosphor layer 50 is converted into white light by passing through the dispersive phosphor layer 60. Even if variations in the concentration of the phosphor 51 in the deposition phosphor layer 50 are found among the LED elements 30 and a part from which a large amount of blue light is emitted, such variations in light emission are attenuated by the emitted light passing through the dispersive phosphor layer 60. Accordingly, by the presence of the dispersive phosphor layer 60, the color unevenness caused by the variations in the phosphor concentration of the deposition phosphor layer 50 is not pronounced.

[0028] Either one or both of the deposition phosphor layer 50 and the dispersed phosphor layer 60 may include, as the phosphors 51 and 61, several types of phosphors, such as a green phosphor and a red phosphor. In this case, the light-emitting device 1 emits white light by mixing the blue light from the LED elements 30, which are blue LEDs, with the green light and the red light obtained by exciting the green phosphor and the red phosphor with the blue light. The green phosphor is a particulate phosphor material such as (BaSr)2SiO4:Eu. 2+ , which absorbs the blue light emitted by the LED elements 30 and converts the wavelengths into green light. The red phosphor is a particulate phosphor material such as CaAlSiN3:Eu 2+which absorbs the blue light emitted by the LED elements 30 and converts the wavelengths into red light.

[0029] Either one or both of the deposition phosphor layer 50 and the dispersed phosphor layer 60 may contain, as the phosphors 51 and 61, the yellow phosphor in addition to the green phosphor and the red phosphor, or they may otherwise contain a combination of the yellow phosphor and the red phosphor, and the like. However, if the types of phosphors are increased too much, the total amount of phosphors is increased and the amount of heat is also large, and therefore, it is disadvantageous in terms of heat radiation. In particular, it is preferable that a phosphor that generates a smaller amount of heat than the phosphor 51 in the deposition phosphor layer 50 be used as the phosphor 61 in the dispersed phosphor layer 60, which is distant from the attached substrate 10.

[0030] The Fig. 5(A) to 5(D) are drawings illustrating examples of concentration distributions of the phosphors in the deposition phosphor layer 50 and the dispersion phosphor layer 60. The left side of each drawing illustrates, with the pattern of light and shadow, the distribution of the particles of the phosphor 51 in the deposition phosphor layer 50 (deposition phosphor layers 50A to 50D). The right side of each drawing illustrates a graph of the concentration distribution f(Z) of the phosphor with respect to the height direction (Z direction). In the following, it is assumed that the upper surface of the attached substrate 10 is the reference (Z = 0) of the height. Although the Fig. 5(A) to 5(D) share the same dispersion phosphor layer 60, the Fig. 5(A) to 5(D) show different concentration distributions of the phosphor 51 in the deposition phosphor layers 50. The relationship of the phosphor concentrations in the deposition phosphor layer 50 and the dispersion phosphor layer 60 may be one of the four patterns shown in the Fig. 5(A) to 5(D).

[0031] In the example of Fig. 5(A), the deposition phosphor layer 50A includes a transparent resin layer 53 located at the top and in a height range from Z1 to Z2 (Z1>Z2), and an intermediate concentration layer 52 containing the phosphor 51 and in a height range from Z2 to zero. In other words, the transparent resin layer 53, which does not contain the phosphor 51, is provided directly below the dispersed phosphor layer 60. The phosphor concentration of the dispersed phosphor layer 60 is f1, and the phosphor concentration of the transparent resin layer 53 is zero. As the height approaches from Z2 to zero, the phosphor concentration of the intermediate concentration layer 52 gradually increases from zero. In particular, near the height zero, the concentration increases rapidly, and near the bottom, the concentration is f2, which is greater than f1.

[0032] In the example of Fig. 5(B) includes the deposition phosphor layer 50B, similar to the case of Fig. 5(A), a transparent resin layer 53 located at the upper end and located in a height range from Z1 to Z2, and an intermediate concentration layer 52' containing the phosphor 51 and located in a height range from Z2 to zero. As the height from Z2 approaches zero, the phosphor concentration of the intermediate concentration layer 52' increases linearly from zero, and near the lower end, f2 is larger than the phosphor concentration f1 of the dispersive phosphor layer 60.

[0033] In the example of Fig. 5(C), the deposition phosphor layer 50C does not contain the transparent resin layer except for the small region of the upper end, and the entire deposition phosphor layer 50C contains the phosphor 51. The phosphor concentration of the deposition phosphor layer 50C increases linearly from zero as the height of the Z1 approaches zero, and near the lower end, the concentration f2 is larger than the phosphor concentrations f1 of the dispersed phosphor layer 60.

[0034] In the example of Fig. 5(D), the deposition phosphor layer 50D does not contain the transparent resin layer at all, and the entire deposition phosphor layer 50D contains the phosphor 51. The phosphor concentration of the deposition phosphor layer 50D is f3, which is smaller than the phosphor concentration f1 of the dispersed phosphor layer 60, at the upper end having the height of Z1, as the height from Z1 approaches zero, the concentration increases linearly from f3, and near the lower end, the concentration is f2, which is larger than f1.

[0035] In all examples of Fig. 5(A) to 5(D), the phosphor concentration f1 of the dispersed phosphor layer 60 is lower than the phosphor concentration f2 of the portion having the highest concentration in the deposition phosphor layer 50. In other words, it is preferable that the concentration of the phosphor 61 in the dispersed phosphor layer 60 be lower than the concentration of the phosphor 51 at the lower end of the deposition phosphor layer 50. Since the dispersed phosphor layer 60 is an auxiliary layer for reducing color unevenness caused by fluctuations in the phosphor concentration during the deposition of the phosphor layer 50, the phosphor concentration of the dispersed phosphor layer 60 is preferably not too high to prevent a decrease in the brightness of the emitted light that has passed through the dispersed phosphor layer 60.Also with regard to heat radiation, the phosphor concentration of the dispersion phosphor layer 60 is preferably not too high.

[0036] In all examples of Fig. 5(A) to 5(D), the phosphor concentration f1 of the dispersed phosphor layer 60 is higher than the phosphor concentration of the zero or the f3 of the portion having the lowest concentration in the deposited phosphor layer 50. In other words, it is preferable that the concentration of the phosphor 61 in the dispersed phosphor layer 60 be higher than the concentration of the phosphor 51 at the upper end (directly below the dispersed phosphor layer 60) of the deposited phosphor layer 50. If the phosphor concentration of the dispersed phosphor layer 60 is too low, an effect of reducing color unevenness cannot be achieved, and thus a certain level of concentration is required.

[0037] In particular, as in the Fig. 5(A) and Fig. 5(B), it is preferable that the upper end (directly below the dispersed phosphor layer 60) of the deposition phosphor layer 50 is the transparent resin layer 53 that does not contain the phosphor 51. When the difference in phosphor concentration between the dispersed phosphor layer 60 and the upper end of the deposition phosphor layer 50 is large, the effect of reducing color unevenness is particularly remarkable. Accordingly, the examples of Fig. 5(A) and Fig. 5(B) is more preferable than the examples of Fig. 5(C) and Fig. 5(D) and in particular the example of Fig. 5(A) is most preferred.

[0038] In contrast to the examples of Fig. 5(A) to 5(D), when the phosphor concentration f1 of the dispersed phosphor layer 60 is lower than the phosphor concentration f3 at the upper end (directly below the dispersed phosphor layer 60) of the deposition phosphor layer 50, the effect of reducing the color unevenness by the dispersed phosphor layer 60 cannot be achieved.

[0039] An upper limit of the phosphor concentration of the dispersed phosphor layer 60 is determined by a relationship between the magnitude of the temperature rise by the phosphor 61 of the dispersed phosphor layer 60 and the heat-resistant temperature of the resin constituting the dispersed phosphor layer 60. A lower limit of the phosphor concentration of the dispersed phosphor layer 60 is determined by a relationship between the degree of fluctuation in the phosphor concentration in the deposition phosphor layer 50, the degree of attenuation of color unevenness by the dispersed phosphor layer 60, and the tolerance range of color unevenness. When the phosphor concentration of the dispersed phosphor layer 60 is high, color unevenness is not pronounced.However, since there is an upper limit to the phosphor concentration as described above, an actual amount of the phosphor 61 dispersed and mixed in the dispersion phosphor layer 60 is determined experimentally.

[0040] When the light-emitting device including the deposition phosphor layer 50 is actually manufactured, since the concentration distribution of the phosphor 51 is different for each product, the chromaticity of the emitted light also varies for each product according to the degree of variation. However, by adjusting the phosphor concentration of the dispersed phosphor layer 60, the differences in chromaticity for each product can be canceled out, so that the chromaticity of the emitted light is within the tolerable range. Accordingly, by providing the dispersed phosphor layer 60 on the deposition phosphor layer 50, the defect rate of the product can be reduced.

[0041] To reduce brightness unevenness, considering providing a diffusion layer instead of the dispersive phosphor layer may be considered. However, for example, if there is a part where a large amount of blue light is locally present, the color unevenness will still exist even if the blue light is diffused with the diffusion layer. In this case, if the yellow light is added to the blue light through the dispersive phosphor layer, the color unevenness will be less obvious, and therefore, for the purpose of reducing color unevenness, it is preferable to use the dispersive phosphor layer instead of the diffusion layer.

[0042] The Fig. Fig. 6 is a flowchart illustrating an example of the manufacturing processes of the light-emitting device 1. In manufacturing the light-emitting device 1, first, as shown in Fig. 3, the LED elements 30 are mounted on the mounting portion 11 of the mounted substrate 10, to which the circuit substrate 20 is adhered (S1). The LED elements 30 are connected to each other via the wires 31, and each LED element 30 is connected to the conductive patterns 23A and 23B via the wires 31 (S2). Next, the resin frame 40 is fixed to the circuit substrate 20 along the edge of the opening 21 (S3).

[0043] Subsequently, all the LED elements 30 are integrally sealed with an uncured sealing resin containing the phosphor 51 excited by the light from the LED elements 30 (S4). While the sealing resin layer is kept in an uncured state, the phosphor 51 is precipitated (settled) in the sealing resin on the side of the attached substrate 10 (S5). Thereafter, the deposition phosphor layer 50 is formed by curing the sealing resin (S6). Finally, the upper surface of the deposition phosphor layer 50 (sealing resin) is covered with the dispersed phosphor layer 60 containing the phosphor 61 excited by the light from the LED elements 30 at a uniform concentration (S7). Accordingly, the manufacture of the light-emitting device 1 obtained by the Fig. 1 and Fig. 2 is completed.

[0044] The Fig. 7 is a perspective view of another light-emitting device 2. The Fig. 8 is a cross-sectional view taken along a line VIII-VIII of the Fig. 7. The light-emitting device 2 differs from the light-emitting device 1 in that a ceramic substrate 20' is included instead of the attached substrate 10 and the circuit substrate 20 of the light-emitting device 1, but the other configurations are the same as those of the light-emitting device 1. The ceramic substrate 20' is a flat substrate and has an upper surface on which the conductive patterns and the connection electrodes 24A and 24B are formed and the LED elements 30 are attached, and the ceramic substrate 20' serves as the attached substrate and the circuit substrate. Even if the ceramic substrate 20' having no opening, as in the Fig.8, the deposition phosphor layer 50 and the dispersed phosphor layer 60, which are the same as those in the light-emitting device 1, can be used. Also, in the light-emitting device 2, similar to the light-emitting device 1, by the presence of the dispersed phosphor layer 60, the color unevenness caused by fluctuations in the phosphor concentration in the deposition phosphor layer 50 is not conspicuous.

Claims

[1] Light-emitting device (1) comprising: a substrate (10), a plurality of light-emitting elements (30) mounted on the substrate (10), a first resin layer (50) which integrally seals the plurality of light-emitting elements (30) and which contains a first yellow phosphor (51) which is excited by light from the plurality of light-emitting elements (30), wherein the closer a portion in which the first yellow phosphor is contained from an upper end far from the substrate (10) to a lower end close to the substrate (10) (51), the higher the concentration of the first yellow phosphor (51), and a second resin layer (60) provided on an upper side of the first resin layer (50) and containing a second yellow phosphor (61) excited by light from the plurality of light-emitting elements (30) and which is the same phosphor as the first yellow phosphor (51) in a uniform concentration, wherein the second yellow phosphor (61) is uniformly dispersed in the second resin layer (60) at a concentration lower than the concentration of the first yellow phosphor (51) at the lower end of the first resin layer (50). [2] The light-emitting device (1) according to claim 1, wherein the concentration of the second yellow phosphor (61) in the second resin layer (60) is higher than the concentration of the first yellow phosphor (51) at the upper end of the first resin layer (50). [3] The light-emitting device (1) according to claim 2, wherein the upper end of the first resin layer (50) is a transparent resin layer not containing the first yellow phosphor (51). [4] A method for producing a light-emitting device (1), comprising the steps of: attaching a plurality of light-emitting elements (30) to a substrate (10), integrally sealing the plurality of light-emitting elements (30) with an uncured resin containing a first yellow phosphor (51) excited by light from the plurality of light-emitting elements (30), thereby forming a first resin layer (50), precipitating the first yellow phosphor (51) on one side of the substrate (10) while keeping the first resin layer (50) in an uncured state, curing of the first resin layer (50) and providing a second resin layer (60) on an upper side of the first resin layer (50) containing a second yellow phosphor (61) excited by light from the plurality of light-emitting elements (30) and which is the same phosphor as the first yellow phosphor (51) in a uniform concentration, wherein the second yellow phosphor (61) is uniformly dispersed in the second resin layer (60) at a concentration lower than the concentration of the first yellow phosphor (51) at the lower end of the first resin layer (50).

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