Light emitting device

Abstract

Disclosed is a light emitting device that comprises: a pair of conductive members; a solder that is arranged on the respective upper surfaces of the pair of conductive members; a light emitting element which comprises a semiconductor laminate, and a pair of electrodes that are arranged on the lower surface of the semiconductor laminate, wherein the lower surfaces of the electrodes are joined to the upper surfaces of the pair of conductive members by the intermediary of the solder; and a light reflective coating member which covers the conductive members, the light emitting element, and the solder. The lower surfaces of the electrodes each have a first lower surface and a second lower surface that is located above the first lower surface. The coating member is disposed between the solder that covers the second lower surfaces of the electrodes and the upper surfaces of the conductive members.

Description

Light-emitting device

[0001] The present disclosure relates to a light emitting device.

[0002] A light emitting device is known that includes a light emitting element soldered onto a conductive member (see, for example, Patent Document 1).

[0003] JP 2019-161108 A

[0004] An object of an embodiment of the present disclosure is to provide a light-emitting device with good light extraction efficiency.

[0005] A light emitting device according to an embodiment has the following configuration: A light emitting element including a pair of conductive members, solder respectively arranged on upper surfaces of the pair of conductive members, a semiconductor laminate, and a pair of electrodes arranged on a lower surface of the semiconductor laminate, wherein the upper surfaces of the pair of conductive members and lower surfaces of the electrodes are joined via the solder, and a light reflective covering member that covers the conductive members, the light emitting element, and the solder, wherein a lower surface of the electrode has a first lower surface and a second lower surface located above the first lower surface, and the covering member is arranged between the solder covering the second lower surface of the electrode and the upper surface of the conductive member.

[0006] According to the embodiment of the present disclosure, a light emitting device with excellent heat dissipation properties can be provided.

[0007] 1A is a schematic top view of a light emitting device according to an embodiment of the present disclosure; FIG. 1B is a schematic cross-sectional view and a partial enlarged view taken along line IB-IB shown in FIG. 1A; FIG. 1C is a schematic cross-sectional view of a light emitting device according to another embodiment of the present disclosure; FIG. 1D is a schematic cross-sectional view of a light emitting device according to another embodiment of the present disclosure;

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper," "lower," "right," "left," and other terms including these terms) will be used as necessary. The use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Furthermore, a plan view refers to a view directly or through-view from the top or bottom. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same parts or members.

[0009] As shown in Figures 1A and 1B, the light-emitting device 100 of the embodiment comprises a conductive member 20, at least one light-emitting element 10 arranged on the conductive member 20 via solder 30, a translucent member 40 arranged on the light-emitting element 10, and a covering member 50 covering the side surface of the light-emitting element 10.

[0010] The conductive member 20 includes a first conductive member 21 and a second conductive member 22. The first conductive member 21 and the second conductive member 22 each have an upper surface 20U, a lower surface 20L opposite the upper surface 20U, and a side surface 20S between the upper surface 20U and the lower surface 20L. The upper surfaces 20U of the first conductive member 21 and the second conductive member 22 may each have a roughened region 20R.

[0011] The solder 30 is disposed between the upper surface 20U of the first conductive member 21 and the first lower surface 12L1 of the electrode 12, and between the upper surface 20U and the second lower surface 12L2 of the second conductive member 22. The light-emitting element 10 is joined to the upper surface 20U of the first conductive member 21 and the upper surface 20U of the second conductive member 22 via the solder 30.

[0012] The light-transmitting member 40 is disposed on the upper surface of the light-emitting element 10 .

[0013] The covering member 50 directly or indirectly covers the upper surfaces 20U of the first conductive member 21 and the second conductive member 22 and the side surfaces of the light-emitting element 10. Furthermore, the covering member 50 covers the side surfaces of the light-transmitting member 40.

[0014] The lower surface of the electrode 12 of the light-emitting element 10 includes a first lower surface 12L1 and a second lower surface 12L2. The second lower surface 12L2 is located above the first lower surface 12L1. In other words, the first lower surface 12L1 is located below the second lower surface 12L2.

[0015] The solder 30 is arranged so as to continuously cover the upper surface 20U of the conductive member 20 and the first lower surface 12L1 and second lower surface 12L2 of the electrode 12. Below the solder 30, there is a portion of the upper surface 20U of the conductive member 20 exposed from the solder 30. In other words, the lower surface of the solder 30 and the upper surface 20U of the conductive member 20 are located apart. In addition, a roughened surface region 20R that has poor wettability and spreadability with the solder 30 can be provided. This allows the conductive member 20 to be exposed in the roughened surface region 20R below the second lower surface 12L2 of the electrode 12 without the solder 30 being arranged therein.

[0016] The covering member 50 is disposed between the solder 30 covering the second lower surface 12L2 of the electrode 12 and the upper surface 20U of the first conductive member 21. In other words, the covering member 50 covers the solder 30.

[0017] In order to improve the light extraction efficiency of the light-emitting element 10, it is important to efficiently reflect the light components generated inside the light-emitting element that are directed toward the electrode 12 (downward) toward the light-transmitting member 40 (upward). Therefore, by disposing a highly light-reflecting covering member 50 in the space between the solder 30 covering the second lower surface 12L2 of the electrode 12 and the upper surface 20U of the conductive member 20, it becomes possible to dispose a large amount of highly reflective material below the second surface 20U of the light-emitting element 10. As a result, light that is directed downward from between the two electrodes 12 is more likely to be reflected by the covering member 50. In other words, the amount of reflected light from the electrode 12 (downward) increases, resulting in a light-emitting device 100 with good light extraction efficiency.

[0018] (Conductive Member) The conductive member 20, which includes the first conductive member 21 and the second conductive member 22, is located between the light emitting element 10 and the mounting substrate and electrically connects them via a conductive material. In detail, the conductive member 20 is electrically connected to the light emitting element 10 via solder, and when the light emitting device 100 is placed on the mounting substrate, the conductive member 20 is electrically connected to the wiring of the mounting substrate via a conductive material such as solder.

[0019] The conductive member 20 is a plate-like metal member patterned into a predetermined shape, and includes a base material serving as a base material and a plating layer formed on the surface of the base material. Examples of the base material include Cu, Al, Ag, Au, Zn, Cr, W, Co, Ni, Fe, Rh, and Ru, or alloys thereof. These may be single layers or laminated structures (e.g., clad materials). A metal plate containing 90% or more of Cu as the main component is preferred. Trace elements may also be included, including one or more of Fe, P, Zn, Ni, Si, Mg, Sn, and Cr. The thickness of the base material is preferably, for example, approximately 50 μm to 800 μm, and more preferably approximately 100 μm to 500 μm.

[0020] The plating layer disposed on the surface of the substrate is preferably made of a material with a higher reflectivity than the substrate. For example, the plating layer may have a single layer or a laminate structure made of Ag, Au, Pt, Pd, Al, W, Ti, Sn, Mo, Ru, or Rh. Alloys containing these materials are also included. Examples of laminate structures include Ni / Pd / Au, Ni / Pt / Au, and Ni / Au / Ag, with Ni / Pd / Au being preferred. The thickness of the plating layer is preferably about 1 μm to 10 μm, and more preferably 1.5 μm to 6 μm.

[0021] The conductive member 20 has an upper surface 20U, a lower surface 20L opposite the upper surface 20U, and a side surface 20S between the upper surface 20U and the lower surface 20L. The side surfaces of the conductive member 20 are exposed to the outside at the side surfaces of the light-emitting device 100. Of the side surfaces 20S of the conductive member 20, the side surfaces 20S that are not exposed to the outside are provided with a plating layer and may be curved surfaces as shown in FIG. 1B or flat surfaces. The side surfaces 20S of the conductive member 20 that are exposed to the outside are not curved surfaces but are substantially flat surfaces. The side surfaces 20S of the conductive member 20 that are exposed to the outside are cut surfaces cut with a dicer or the like. This cut surface is composed of a shear surface that is mainly made of the base material of the conductive member 20 and has cut marks such as fine vertical streaks, and a fracture surface that is mainly made of the base material and is slightly rougher than the shear surface. The upper surface 20U of the first conductive member 21 and the upper surface 20U of the second conductive member 22 are flat surfaces that are arranged to be flush with each other and are not exposed to the outside. The lower surface 20L of the first conductive member 21 and the lower surface 20L of the second conductive member 22 are flat surfaces that are arranged to be flush with each other and are exposed to the outside. The light-emitting element 10 is arranged to straddle the upper surface 20U of the first conductive member 21 and the upper surface 20U of the second conductive member 22. In other words, below the light-emitting element 10, the side surface 20S of the first conductive member 21 and the side surface 20S of the second conductive member 22 are arranged to face each other.

[0022] By irradiating the upper surface 20U of the conductive member 20 with laser light, a portion of the plating layer disposed on the surface of the base material can be turned into a roughened region 20R, which has poor solder wettability. This makes it possible to control the position where the solder wets and spreads. Specifically, when irradiated with laser light, a portion of the plating layer on the surface melts, forming the roughened region 20R with multiple irregularities. The irregularities of this roughened region 20R can reduce the wettability and spread of the solder. In other words, a space can be created between the solder 30 and the roughened region 20R.

[0023] Alternatively, instead of irradiating with laser light, resist may be applied in advance to a portion of the upper surface 20U of the conductive member 20, thereby reducing the positions where the solder spreads without forming the roughened surface region 20R.

[0024] Furthermore, if the base material of the conductive member 20 is Cu and the plating layer has a laminated structure, for example, Ni / Pd / Au, the Pd and Au on the surface are partially or completely removed by irradiation with laser light, exposing the Ni from the Pd and Au. Ni has poorer solder wettability than Au or Pd. Exposing such Ni on the surface can further reduce the spread of solder. The unevenness of the roughened surface region 20R and the exposed Ni can more efficiently reduce the spread of solder.

[0025] The roughened surface region 20R is located on the upper surface 20U of the conductive member 20 and is disposed in a planar view where the upper surface 20U of the conductive member 20 and the second lower surface 12L2 of the electrode 12 overlap. The planar shape of the roughened surface region 20R can be any shape as long as it is disposed in a planar view where the upper surface 20U of the conductive member 20 and the second lower surface 12L2 of the electrode 12 overlap. Examples include a linear shape or a rectangular frame shape surrounding the first lower surface 12L1 of the electrode 12. The width of the roughened surface region 20R is preferably approximately 10 μm to 200 μm, and more preferably approximately 40 μm to 100 μm. In the roughened surface region 20R formed by laser light irradiation, the height of the convex portions of the unevenness from the upper surface 20U is preferably approximately 1 μm to 10 μm, and more preferably approximately 4 μm to 10 μm. The surface roughness Ra of the roughened surface region 20R is preferably approximately 1 μm to 10 μm.

[0026] The dominant wavelength, output (intensity), diameter of the irradiation spot, and movement speed of the irradiation spot of the first laser light B1 can be set in consideration of the height of the convex portion that can reduce the wetting and spreading of the solder 30, depending on the composition and thickness of the plating layer placed on the substrate surface or the volume of the solder 30, which is a conductive material.

[0027] The first laser beam B1 may also be set under conditions that allow removal of the plating layer material at the irradiated portion. For example, consider a case where the conductive member 20 is made of Cu as the base material and the plating layer disposed on the surface of the substrate is made of a material containing Ni / Pd / Au. In this case, it is preferable to use a first laser light source L1 capable of emitting green laser light with a dominant wavelength of 532 nm as the first laser beam B1. The output of the first laser light source L1 is preferably 0.1 W to 4 W, and more preferably approximately 1 W. The first laser beam B1 is emitted by continuous oscillation or pulse oscillation. For example, in the case of pulse oscillation, the heat amount per pulse of the first laser beam B1 can be 7 μJ to 10 μJ. The irradiation spot diameter of the first laser beam B1 can be, for example, 15 μm to 30 μm. The irradiation spot movement speed can be, for example, 500 mm / s to 1500 mm / s. Examples of the first laser light source L1 capable of emitting such a first laser beam B1 include a YAG laser, a YVO ４ Examples include second harmonics of lasers.

[0028] (Light-emitting element) The light-emitting element is a semiconductor element that emits light by itself when a voltage is applied, and known semiconductor elements made of nitride semiconductors or the like can be used. For example, a semiconductor light-emitting element such as a light-emitting diode can be used as the light-emitting element 10. The light-emitting element 10 includes a semiconductor laminate 11 and a pair of positive and negative electrodes 12. The semiconductor laminate 11 includes, for example, an element substrate made of sapphire or the like, and a semiconductor layer formed thereon. Alternatively, the semiconductor laminate 11 can be made of only a semiconductor layer without an element substrate.

[0029] The shape of the light-emitting element 10 in a planar view can be a polygon such as a triangle, a rectangle, or a hexagon. The size of the light-emitting element 10 can be, for example, 100 μm or more and 3000 μm or less on a side in a planar view. Specifically, the light-emitting element 10 can be a square with a side of approximately 600 μm, 1000 μm, 1400 μm, or 1700 μm. The light-emitting element 10 can also be a rectangle having long and short sides in a planar view. For example, the size can be 1100 μm x 200 μm.

[0030] The semiconductor stack 11 includes an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer sandwiched between them. ｘ Al ｙ Ga １－ｘ－ｙ N (0≦x, 0≦y, x+y≦1).

[0031] The semiconductor laminate 11 may have a structure including one or more light-emitting layers between an n-type semiconductor layer and a p-type semiconductor layer, or may have a structure in which a structure including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer in that order is repeated multiple times.

[0032] When the semiconductor stack 11 includes multiple light-emitting layers, the light-emitting layers may have different emission peak wavelengths, or may have the same emission peak wavelength. Note that the same emission peak wavelength also includes cases where the emission peak wavelength varies by a few nanometers. The combination of emission peak wavelengths between the multiple light-emitting layers can be appropriately selected. For example, when the semiconductor stack includes two light-emitting layers, the light-emitting layers can be selected from a combination of blue light and blue light, green light and green light, red light and red light, ultraviolet light and ultraviolet light, blue light and green light, blue light and red light, or green light and red light.

[0033] The light-emitting element 10 has at least a pair of electrodes 12 on the lower surface side of the semiconductor laminate. In other words, one light-emitting element 10 has at least one positive electrode and at least one negative electrode as the electrodes 12. In the light-emitting device 100A shown in Fig. 1A, the light-emitting element 10 has one positive electrode and one negative electrode. The positive electrode and negative electrode each have a rectangular shape in a plan view.

[0034] The lower surfaces of the electrodes 12 of the light-emitting element 10 include a first lower surface 12L1 and a second lower surface 12L2, with the first lower surface 12L1 being located below the second lower surface 12L2. As shown in FIG. 1A , the first lower surface 12L1 and the second lower surface 12L2 each have a rectangular shape in plan view, with one long side shared between them. The second lower surfaces 12L2 of the two electrodes 12 may be located on opposing sides, on the opposite side, or on both sides. In FIG. 1A , the first lower surface 12L1 and the second lower surface 12L2 are illustrated with different hatching.

[0035] The electrode 12 of the light-emitting element 10 can be made of a good electrical conductor, such as gold, silver, copper, platinum, iron, nickel, or an alloy thereof. The electrode 12 is electrically connected to an ohmic electrode provided on the semiconductor laminate 11 inside the light-emitting element 10. The thickness of the electrode 12 (here, the maximum thickness, i.e., the distance between the first lower surface 12L1 and the lower surface of the semiconductor laminate 11) can be, for example, 0.5 μm to 100 μm, more preferably 5 μm to 50 μm.

[0036] The distance (thickness) from the lower surface of the semiconductor laminate 11 to the second lower surface 12L2 can be 10% to 80% of the distance (thickness) from the lower surface of the semiconductor laminate 11 to the first lower surface 12L1. By making the distance (thickness) from the lower surface of the semiconductor laminate 11 to the second lower surface 12L2 smaller than the distance (thickness) from the lower surface of the semiconductor laminate 11 to the first lower surface 12L1, a portion of the upper surface 20U of the conductive member 20 can be exposed from the solder 30 when the solder 30 wets and spreads.

[0037] Furthermore, when the first lower surface 12L1 and the second lower surface 12L2 each have a rectangular shape in plan view as shown in FIG. 1A , the length of the short side of the second lower surface 12L2 in plan view can be 10% to 150%, preferably 10% to 100%, and more preferably 10% to 50% of the length of the short side of the first lower surface 12L1. By making the length of the short side of the second lower surface 12L2 in plan view longer than the length of the short side of the first lower surface 12L1, a larger portion of the upper surface 20U of the conductive member 20 is exposed from the solder 30 when the solder 30 wets and spreads, thereby improving light extraction efficiency. Furthermore, by making the length of the short side of the second lower surface 12L2 in plan view shorter than the length of the short side of the first lower surface 12L1, the contact area between the electrode 12 and the upper surface 20U of the conductive member 20 increases, thereby improving heat dissipation.

[0038] (Solder) The solder 30 is a conductive member that electrically and mechanically connects the pair of positive and negative electrodes 12 of the light-emitting element 10 to the conductive member 20. One of the electrodes 12 of the light-emitting element 10 is electrically joined to the first conductive member 21 via the solder 30, and the other of the electrodes 12 of the light-emitting element 10 is electrically joined to the second conductive member 22 via the solder 30. The solder 30 preferably contacts the entire lower surface, including the first lower surface 12L1 and the second lower surface 12L2, of the electrode 12 of the light-emitting element 10. The solder 30 may have a thickness of 1 μm to 20 μm between the light-emitting element 10 and the upper surface 20U of the conductive member 20.

[0039] The solder 30 is disposed in a position where the entire solder 30 overlaps the light-emitting element 10 in a plan view. However, a portion of the solder 30 may not overlap the light-emitting element 10, i.e., a portion may protrude from the light-emitting element 10. The solder 30 is disposed so as to continuously cover the upper surface 20U of the conductive member 20 and the first lower surface 12L1 and second lower surface 12L2 of the electrode 12. At this time, there is a portion on the lower surface of the solder 30 where the upper surface 20U of the conductive member 20 is exposed from the solder 30. In other words, the lower surface of the solder 30 and the upper surface 20U of the conductive member 20 are located at a distance. Examples of materials for the solder 30 include Au—Sn, Sn—Ag—Cu, Sn—Cu, Sn—Sb, Sn—Bi, Sn—In, and Sn—Pb.

[0040] (Coating Member) The covering member 50 is a member that covers the light-emitting element 10 and is provided to protect the light-emitting element 10 from external forces, dust, moisture, etc., and to control excess light leakage and efficiently use the light emitted from the light-emitting element. The covering member 50 covers the upper surface 20U of the first conductive member 21, the upper surface 20U of the second conductive member 22, and the side surface of the light-emitting element 10. When a light-guiding member 60 that joins the light-transmitting member 40 and the light-emitting element 10 is provided, the covering member 50 covers the side surface of the light-emitting element 10 via the light-guiding member 60. The covering member 50 also covers the lower surface of the semiconductor stack 11 of the light-emitting element 10 and the side surface 20S of the conductive member 20. The covering member 50 can be in contact with the lower surface of the light-transmitting member 40. The covering member 50 can also cover the side surface of the light-transmitting member 40. Furthermore, the covering member 50 also covers the area between the solder 30 and the upper surface 20U of the conductive member 20 below the second lower surface 12L2 of the electrode 12. When a highly reflective material is used for the covering member 50, the light components that would conventionally be absorbed by the electrode 12 can be reflected upward, making it possible to improve the light extraction efficiency.

[0041] The covering member 50 may be light-reflective, light-absorbing, or light-transmitting. A resin member can be used as the base material of the covering member 50. Examples of resin members that can be used include thermosetting resins such as silicone resin, silicone-modified resin, epoxy resin, and phenolic resin, and thermoplastic resins such as polycarbonate resin, acrylic resin, methylpentene resin, and polynorbornene resin. Silicone resin, which has excellent light resistance and heat resistance, is particularly suitable. When using a resin member, the covering member 50 can be formed by compression molding or transfer molding after the light-emitting element 10 and the conductive member 20 are joined with solder 30. In this case, the covering member 50 may be formed using a pre-molten resin member, or a powdered resin member may be arranged to cover the light-emitting element 10, the conductive member 20, and the like, and then molded.

[0042] The covering member 50 may contain a light-reflecting material such as titanium oxide or zinc oxide. Alternatively, the covering member 50 may contain a light-absorbing material such as carbon black or titanium black. The covering member 50 may contain both a light-reflecting material and a light-absorbing material. In this case, both the light-reflecting material and the light-absorbing material may be contained in a single base material. Alternatively, the covering member 50 may include a light-reflective first covering member in contact with the light-emitting element 10 and a light-absorbing second covering member on the outside of the first covering member. The covering member 50 may also be composed of an inorganic material containing, for example, an alkali metal silicate. In this case, the covering member 50 may further contain boron nitride, aluminum oxide, titanium oxide, or zirconium oxide. The covering member 50 may also include both a resin material and an inorganic material. When the covering member 50 is light-reflective, its reflectance at the emission peak wavelength of light emitted from the light-emitting element 10 is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more.

[0043] (Light-Transmitting Member) The light-transmitting member 40 is disposed on the upper surface of the light-emitting element 10 and is a member capable of transmitting light emitted from the light-emitting element 10 and emitting it to the outside. The light-transmitting member 40 is disposed so as to cover the upper surface of the semiconductor laminate 11 of the light-emitting element 10. The light emitted from the light-emitting element 10 is emitted to the outside through the light-transmitting member 40. The shape of the light-transmitting member 40 may be flat, or may be convex so that the area through which light emitted from the light-emitting element 10 is emitted to the outside is smaller than the area through which light enters the light-transmitting member 40. When the light-transmitting member 40 has a convex shape in cross section, it is desirable to cover it with a reflective covering member 50 so that the top surface is exposed. By covering the convex-shaped light-transmitting member 40 with the covering member 50 so that the top surface is exposed, the amount of light per light extraction area can be increased.

[0044] When the light-transmitting member 40 has a convex shape in cross section, the upper surface other than the top surface may be covered with a light-transmitting diffusing member containing a diffusing material or the like. When such a diffusing member covering a portion of the upper surface of the light-transmitting member 40 is provided, the side surfaces of the diffusing member are preferably covered with a light-reflective covering member 50. By covering the upper surface other than the top surface of the convex light-transmitting member 40 with the light-transmitting covering member 50, the amount of light per light extraction area can be partially adjusted. In other words, by providing the upper surface of the light-transmitting member 40 with a portion exposed to the outside (the top surface) and a portion covered with the diffusing member that is more difficult to extract light than the top surface, the light-emitting surface of the light-emitting device can be made into a light-emitting surface having portions with different brightnesses.

[0045] The shapes of the upper and lower surfaces of the light-transmitting member 40 as viewed from above are preferably the same and substantially the same as those of the light-emitting element 10. By making the area the same as that of the light-emitting element 10, light from the light-emitting element 10 can be efficiently incident into the light-transmitting member 40, and the light can be efficiently transmitted without being affected by absorption by the covering member 50. Furthermore, the shapes of the upper and lower surfaces of the light-transmitting member as viewed from above can be the same and can be slightly larger than the upper surface of the light-transmitting member. By making the area slightly larger than that of the light-emitting element 10, it is possible to reduce incident loss due to misalignment when placing the light-transmitting member on the light-emitting element 10.

[0046] Furthermore, the side surfaces of the light-transmitting member 40 may be exposed from the covering member 50. In other words, the entire upper surface of the light-emitting device 100 may be made of the light-transmitting member 40. By exposing the side surfaces of the light-transmitting member 40 from the covering member 50, light can also be extracted from the side surfaces of the light-transmitting member 40, thereby improving the amount of light.

[0047] 1B and other figures, light is emitted to the outside from the upper surface of the light-transmitting member 40. The light-transmitting member 40 may be made of a resin material, an inorganic material, glass, or a combination thereof. The light-transmitting member 40 preferably has a transmittance of 60% or more, more preferably 70% or more, and even more preferably 80% or more, for light of the peak wavelength emitted from the light-emitting element 10.

[0048] The resin material for the translucent member 40 can be a thermosetting resin such as silicone resin, silicone-modified resin, epoxy resin, or phenolic resin, or a thermoplastic resin such as polycarbonate resin, acrylic resin, methylpentene resin, or polynorbornene resin. Silicone resin, which has excellent light resistance and heat resistance, is particularly suitable. The inorganic material for the translucent member 40 can be silicon oxide, aluminum oxide, or the like. The glass material can be alkali-free glass, soda glass, soda-lime glass, borosilicate glass, aluminosilicate glass, quartz glass, low-alkali borosilicate glass, or the like.

[0049] The light-transmitting member 40 may be made of only these light-transmitting members, or may be made of these light-transmitting members as a base material containing a phosphor that is excited by light from the light-emitting element and converts it into light of a different wavelength, a light-scattering agent, etc. Furthermore, the light-transmitting member 40 may be made by sintering a phosphor, or by sintering a phosphor to which a light-scattering agent has been added.

[0050] Examples of the phosphor that can be used include yttrium aluminum garnet phosphors, lutetium aluminum garnet phosphors, terbium aluminum garnet phosphors, CCA phosphors, SAE phosphors, chlorosilicate phosphors, silicate phosphors, oxynitride phosphors such as β-sialon phosphors and α-sialon phosphors, nitride phosphors such as LSN phosphors, BSESN phosphors, SLA phosphors, CASN phosphors and SCASN phosphors, fluoride phosphors such as KSF phosphors, KSAF phosphors and MGF phosphors, quantum dots having a perovskite structure, II-VI quantum dots, III-V quantum dots, and quantum dots having a chalcopyrite structure.

[0051] Examples of light scattering agents that can be used include particles of titanium oxide, silicon oxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass.

[0052] (Light-guiding member) The light-guiding member 60 is a member for joining the light-emitting element 10 and the light-transmissive member 40 arranged above the light-emitting element. The light-guiding member 60 can guide light from the light-emitting element 10 to the light-transmissive member 40, thereby improving the light extraction efficiency. The light-guiding member 60 is arranged between the light-emitting element 10 and the light-transmissive member 40, and may cover part or all of the side surface of the light-emitting element 10.

[0053] When the size of the light-transmitting member 40 is larger than the light-emitting element 10 in a plan view, the light-guiding member 60 is formed in a triangular cross section so as to widen toward the light-transmitting member 40. However, the cross section of the outer surface of the light-guiding member 60 is not limited to a linear shape and may be curved. For example, the curved shape of the light-guiding member 60 may be a curved shape that bulges toward the covering member 50 side or a curved shape that is recessed toward the light-emitting element 10 side.

[0054] From the viewpoint of ease of handling and processing, it is preferable to use a resin material for the light guide member 60. As the resin material, a resin material made of a hybrid resin or the like containing one or more of silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, acrylic resin, and fluororesin can be used. The viscosity of the resin material used to form the light guide member 60 and the wettability of the resin material with the light emitting element 10 can be adjusted as appropriate.

[0055] DESCRIPTION OF SYMBOLS 100... Light emitting device 10... Light emitting element 11... Semiconductor laminate 12... Electrode 12L... Lower surface of electrode (12L1... First lower surface, 12L2... Second lower surface) 20... Conductive member (20U... Upper surface, 20L... Lower surface, 20S... Side surface, 20R... Rough surface area) 21... First conductive member 22... Second conductive member 30... Solder 40... Light-transmitting member 50... Covering member 60... Light-guiding member

Claims

1. A light-emitting element comprising: a pair of conductive members; solder respectively arranged on the upper surfaces of the pair of conductive members; a semiconductor laminate; and a pair of electrodes arranged on the lower surface of the semiconductor laminate, wherein the upper surfaces of the pair of conductive members and the lower surfaces of the electrodes are joined via the solder; and a light-reflective covering member that covers the conductive members, the light-emitting element, and the solder, wherein the lower surfaces of the electrodes have a first lower surface and a second lower surface located above the first lower surface, and the covering member is arranged between the solder that covers the second lower surface of the electrode and the upper surface of the conductive members.

2. The light emitting device according to claim 1, wherein the upper surface of the conductive member has a roughened area at a position overlapping the second lower surface of the electrode in a plan view.

3. The light emitting device according to claim 1 or 2, wherein the second lower surface of the electrode is located on a side where the pair of electrodes face each other.

4. The light emitting device according to any one of claims 1 to 3, wherein the second lower surface of the electrode is located on the side opposite to the side where the pair of electrodes face each other.

5. The light emitting device according to any one of claims 1 to 4, wherein the second lower surface of the electrode is positioned so as to surround the first lower surface in a plan view.

Images