JP6805505B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting device.

In recent years, various electronic components have been proposed and put into practical use, and the performance required for them is also increasing. In particular, electronic components are required to maintain their performance for a long time even in a harsh usage environment. Such a requirement is no exception to a light emitting device using a semiconductor light emitting element such as a light emitting diode (LED: Light Emitting Diode). That is, in the general lighting field and the in-vehicle lighting field, the performance required for the light emitting device is increasing day by day, and further high output (high brightness) and high reliability are required. In particular, in order to increase the output, operation at a high operating temperature is inevitably required. Further, light diffusivity is also required in fields such as backlight light sources and lighting fixtures. In order to improve the light diffusivity of the light emitting device, a method of mixing a light diffusing material with the sealing resin is known.

For example, Patent Document 1 discloses that unevenness in light radiation intensity is suppressed by arranging a light scattering member on the upper surface of a light emitting element. Further, Patent Document 1 also discloses a form including a wavelength conversion material.

JP-A-2007-266356

However, in a light emitting device in which a coating resin contains a wavelength conversion material in addition to a light scattering material, the emission color may change when the temperature changes.

Therefore, it is an object of the light emitting device of the embodiment according to the present invention to provide a light emitting device in which the change in emission color is small even if the temperature changes.

The light emitting device according to the embodiment of the present invention is a light emitting device having a light emitting element, a coating resin covering the light emitting element, a wavelength conversion material contained in the coating resin, and a light diffusing material contained in the coating resin. There,
The light diffusing material contains glass particles
The first refractive index n1 at 25 ° C. at the peak wavelength of the light emitting element of the coating resin is 1.48 or more and 1.60 or less.
The second refractive index n2 of the coating resin at 100 ° C. at the peak wavelength of the coating resin is lower than the first refractive index n1, and the difference in refractive index between the first refractive index n1 and the second refractive index n2 is 0. .0075 and above,
The third refractive index n3 of the light diffusing material at 25 ° C. at the peak wavelength of the light diffusing material is higher than the first refractive index n1.

According to the light emitting device according to the embodiment of the present invention, it is possible to provide a light emitting device in which the change in emission color due to a temperature change is small.

It is a top view which shows an example of the light emitting device of 1st Embodiment. It is sectional drawing which shows an example of the light emitting device of 1st Embodiment. It is an image figure which shows the refractive index with respect to the temperature change of a coating resin, a light diffusing material, and a light scattering particle. It is a top view which shows an example of the light emitting device of 2nd Embodiment. It is sectional drawing which shows an example of the light emitting device of 2nd Embodiment. It is a top view which shows an example of the light emitting device of 3rd Embodiment. It is sectional drawing which shows an example of the light emitting device of 3rd Embodiment. It is a top view which shows an example of the light emitting device of 4th Embodiment. It is an end view which shows an example of the light emitting device of 4th Embodiment. It is sectional drawing which shows an example of the light emitting device of 5th Embodiment. It is a figure which shows the light distribution characteristic of the light emitting device of 5th Embodiment. It is sectional drawing which shows an example of the light emitting device of 6th Embodiment. It is sectional drawing which shows an example of the light emitting device of 7th Embodiment. It is a figure which shows the CIE chromaticity coordinates in the temperature change of Example 1. FIG. It is a figure which shows the CIE chromaticity coordinates in the temperature change of Example 2. It is a figure which shows the CIE chromaticity coordinates in the temperature change of Example 3. It is a figure which shows the luminous flux in the temperature change of Example 3.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the light emitting device described below is for embodying the technical idea, and the present invention is not limited to the following. Further, the contents described in one embodiment and the embodiment can be applied to other embodiments and the examples.
Further, in the following description, members having the same or the same quality are shown with the same name and reference numeral, and duplicate detailed description will be omitted as appropriate. Further, each element constituting the present invention may be configured such that a plurality of elements are composed of the same member and the plurality of elements are combined with one member, or conversely, the function of one member is performed by the plurality of members. It can also be shared and realized.

[First Embodiment]
1A and 1B are schematic structural views showing an example of the light emitting device of the first embodiment, FIG. 1A is a top view, and FIG. 1B is a sectional view taken along line I-I of FIG. 1A. FIG. 2 is an image diagram showing the refractive index of the coating resin, the light diffusing material, and the light scattering particles in a temperature change. The light scattering particles are used in the second embodiment described later.

The light emitting device 100 according to the first embodiment includes a light emitting element 14, a coating resin 19, and a light diffusing material 17.

The light emitting element 14 is flip-chip mounted via a connecting member 13 so as to straddle a pair of conductor wirings 12 provided on the surface of the substrate 11. Although most of the conductor wiring 12 is covered with the insulating member 15, the region of the upper surface of the conductor wiring 12 that is electrically connected to the light emitting element 14 is exposed from the insulating member 15. An underfill 16 is formed on the lower portion of the light emitting element 14 (that is, between the light emitting element 14 and the substrate 11) and on the side surface of the light emitting element 14.

A coating resin 19 containing a light diffusing material 17 is formed on the upper portion (light extraction surface side) of the light emitting element 14.

The refractive index of the coating resin 19 is lower at 100 ° C. than at 25 ° C. Therefore, the difference in refractive index between the coating resin 19 and air is smaller at 100 ° C. than at 25 ° C. Therefore, the amount of light emitted from the light emitting element 14 is surface-reflected and totally reflected at the interface between the coating resin 19 and the air at 100 ° C. than at 25 ° C. As a result, the amount of light scattered by the light diffusing material 17 is reduced by returning to the coating resin 19 again.

Therefore, in order to suppress the change in the light distribution characteristics, it is preferable that the difference in the refractive index of the coating resin 19 at 25 ° C. and 100 ° C. is small. However, according to the embodiment of the present invention, even if a material in which the refractive index of the coating resin 19 at 100 ° C. is 0.0075 or more lower than the refractive index of the coating resin at 25 ° C. is selected, the light distribution characteristics change with respect to temperature. Can be reduced.

The coating resin 19 contains a light diffusing material 17 having a refractive index equal to or higher than that of the coating resin 19 at 25 ° C. Further, by selecting a material in which the temperature coefficient of the refractive index of the light diffusing material 17 is smaller than the temperature coefficient of the refractive index of the coating resin 19, the difference in the refractive index between the coating resin 19 and the light diffusing material 17 is 25 ° C. It is larger at 100 ° C than at times. Therefore, the ratio of the light emitted from the light emitting element 14 reflected at the interface between the coating resin 19 and the light diffusing material 17 increases at 100 ° C. than at 25 ° C.

By doing so, as the temperature rises, the amount of light reflected on the surface and totally reflected at the interface between the coating resin 19 and the air decreases, but the amount of light reflected at the interface between the coating resin 19 and the light diffuser 17 increases. , The amount of light scattered in the coating resin 19 can be made substantially constant. As a result, even if the temperature changes, the change in the light distribution characteristics can be reduced.

However, if the difference in refractive index between the light diffusing material 17 and the coating resin 19 at 25 ° C. is made too large, the relative change in the refractive index due to the temperature difference becomes small, and the rate of increase in the amount of light scattering accompanying the temperature rise becomes small. Therefore, the refractive index of the light diffusing material 17 at 25 ° C. is preferably the same or higher in the range of 0 to 0.15 than the refractive index of the coating resin 19, more preferably in the range of 0 to 0.1, and further preferably. Is in the range 0-0.05.

The difference in the refractive index of the coating resin 19 at 25 ° C. and 100 ° C. is not particularly limited, but the refractive index of the coating resin 19 at 100 ° C. is 0, rather than the refractive index of the coating resin 19 at 25 ° C. It is preferably as low as 0075 to 0.075. By setting the difference in the refractive index of the coating resin 19 between 25 ° C. and 100 ° C. within this range, it becomes easier to control light scattering.

As for the refractive index of the coating resin 19, the higher the refractive index, the smaller the difference in the refractive index from the light emitting element 14, and the efficiency of light extraction from the light emitting element 14 is improved, which is preferable. Therefore, the refractive index of the coating resin 19 at 25 ° C. is not particularly limited, but is preferably 1.45 or more, and more preferably 1.5 or more.

When the temperature coefficient of the refractive index of the light diffusing material 17 is smaller than the temperature coefficient of the refractive index of the coating resin 19, the difference in the refractive index of the light diffusing material 17 between 25 ° C. and 100 ° C. is 25 ° C. It is smaller than the difference in the refractive index of the coating resin 19 at 100 ° C.

As described above, according to the light emitting device 100 according to the first embodiment, by containing the light diffusing material 17 in the coating resin 19, even if the refractive index of the coating resin 19 changes with temperature, the light distribution characteristics depend on the temperature. The sex can be reduced.

[Second Embodiment]
3A and 3B are schematic structural views showing an example of the light emitting device of the second embodiment, FIG. 3A is a top view, and FIG. 3B is a sectional view taken along line II-II of FIG. 3A. FIG. 2 is an image diagram showing the refractive index of the coating resin, the light diffusing material, and the light scattering particles in a temperature change. The present embodiment is different from the light emitting device 100 according to the first embodiment in that the coating resin 19 contains light scattering particles 18 in addition to the light diffusing material 17. Except for the others, the structure is substantially the same as that described in the first embodiment.

The light emitting device 200 according to the second embodiment includes a light emitting element 14, a coating resin 19, a light diffusing material 17, and light scattering particles 18.

A coating resin 19 containing a light diffusing material 17 and light scattering particles 18 is formed on the upper portion (light extraction surface side) of the light emitting element 14.

The coating resin 19 contains light scattering particles 18 having a refractive index equal to or lower than that of the coating resin 19 at 100 ° C. Since the temperature coefficient of the refractive index of the light scattering particles 18 is smaller than the temperature coefficient of the refractive index of the coating resin 19, the difference in refractive index between the coating resin 19 and the light scattering particles 18 is 25 ° C. than at 100 ° C. It becomes larger at the time of. Therefore, the light emitted from the light emitting element 14 at 25 ° C. is scattered at the interface between the coating resin 19 and the light scattering particles 18 at 25 ° C. than at 100 ° C. That is, by including the light scattering particles 18, the light scattering property at 25 ° C. is higher than that at 100 ° C.

By doing so, even when the concentration of the light diffusing material 17 in the coating resin 19 is increased to increase the light scattering at 100 ° C. in order to further widen the light distribution angle, the light scattering at 25 ° C. is also high. This makes it easier to control the scattering of light.

That is, as the temperature rises, the amount of light reflected at the interface between the coating resin 19 and the light diffusing material 17 increases, but the amount of light reflected at the interface between the coating resin 19 and the light scattering particles 18 decreases, so that the coating resin Even if the refractive index of 19 changes with temperature, the temperature dependence of the light distribution characteristics can be reduced.

However, if the difference in refractive index between the light diffusing material 17 and the coating resin 19 at 25 ° C. is made too large, the relative change in the refractive index due to the temperature difference becomes small, and the rate of increase in the amount of light scattering accompanying the temperature rise becomes small. When the light scattering particles 18 are contained, the refractive index of the light diffusing material 17 at 25 ° C. is not particularly limited, but is the same or higher than the refractive index of the coating resin 19 in the range of 0 to 0.15. It is more preferable, more preferably in the range of 0 to 0.1, and further preferably in the range of 0 to 0.05.

If the difference in refractive index between the light-scattering particles 18 and the coating resin 19 at 100 ° C. is made too large, the relative change in the refractive index due to the temperature difference becomes small, and the reduction rate of the amount of light scattering due to the temperature rise becomes small. Therefore, the refractive index of the light scattering particles 18 at 100 ° C. is not particularly limited, but it is preferably the same or lower than the refractive index of the coating resin 19 at 100 ° C. in the range of 0 to 0.1.

Further, the difference in refractive index between the coating resin 19 and air is smaller at 100 ° C. than at 25 ° C. Therefore, when the difference in refractive index between the coating resin 19 and the light diffusing material 17 at 100 ° C. is larger than the difference in refractive index between the coating resin 19 and the light scattering particles 18 at 25 ° C., the temperature change in the light distribution characteristics can be suppressed. Therefore, it is preferable.

When the temperature coefficient of the refractive index of the light scattering particles 18 is smaller than the temperature coefficient of the refractive index of the coating resin 19, the difference in the refractive index of the light scattering particles 18 between 25 ° C. and 100 ° C. is 25. It is smaller than the difference in the refractive index of the coating resin 19 between ° C. and 100 ° C.

As described above, according to the light emitting device 200 according to the second embodiment, the refractive index of the coating resin 19 changes depending on the temperature by containing the light diffusing material 17 and the light scattering particles 18 in the coating resin 19. Even so, the temperature dependence of the light distribution characteristics can be reduced.

In the present specification, unless otherwise specified, the measurement wavelength of the refractive index is D line (589 nm). Further, unless otherwise specified, the difference in refractive index is an absolute value.

The refractive index can be measured, for example, with an Abbe refractometer. If it is not possible to measure with an Abbe refractometer due to the size of the member or the like, the member can be specified and the refractive index can be obtained from the measurement results of a member similar to the specified member.

Hereinafter, preferred embodiments of the light emitting device according to the first and second embodiments described above and the components in the third to seventh embodiments described below will be described.
(Hypokeimenon 11)
The substrate is a member on which a light emitting element is placed. The substrate has a conductor wiring on its surface for supplying electric power to the light emitting element.

Examples of the material of the substrate include resins such as phenol resin, epoxy resin, polyamide resin, polyimide resin, BT resin, polyphthalamide (PPA), and polyethylene terephthalate (PET), and ceramics. Among them, it is preferable to select a resin as an insulating material from the viewpoint of low cost and ease of molding. Alternatively, in order to obtain a light emitting device having excellent heat resistance and light resistance, it is preferable to select ceramics as the material of the substrate.

Examples of the material of the ceramics include alumina, mullite, forsterite, glass ceramics, nitride-based (for example, AlN), and carbide-based (for example, SiC). Of these, ceramics made of alumina or containing alumina as a main component are preferable.
When a resin is used as the material constituting the substrate 11, glass fibers and inorganic fillers such as SiO ₂ , TiO ₂ and Al ₂ O ₃ are mixed with the resin to improve the mechanical strength and reduce the coefficient of thermal expansion. , It is also possible to improve the light reflectance. Further, as the substrate, a so-called metal substrate in which an insulating layer is formed on a metal member may be used as long as the pair of conductor wiring can be insulated and separated.

(Conductor wiring 12)
The conductor wiring is a member that is electrically connected to the electrodes of the light emitting element and supplies a current (electric power) from the outside. That is, it plays a role as an electrode or a part thereof for energizing from the outside. It is usually formed at least two apart, positive and negative.

The conductor wiring is formed on at least the upper surface of the substrate which is the mounting surface of the light emitting element. The material for the conductor wiring can be appropriately selected depending on the material used as the substrate, the manufacturing method, and the like. For example, when ceramic is used as the material of the substrate 11, the material of the conductor wiring is preferably a material having a high melting point that can withstand the firing temperature of the ceramic sheet, and for example, a metal having a high melting point such as tungsten or molybdenum is used. Is preferable. Further, it may be coated with another metal material such as nickel, gold, or silver by plating, sputtering, vapor deposition, or the like.

When a glass epoxy resin (an epoxy resin filled with glass fibers) is used as the base material, the conductor wiring material is preferably a material that is easy to process, and for example, copper can be used. When an injection-molded epoxy resin is used, the material of the conductor wiring is preferably a member that is easily punched, etched, bent, etc., and has a relatively large mechanical strength, for example. , Copper can be used. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron and nickel, metal layers such as iron-nickel alloys, phosphor bronze, iron-containing copper and molybdenum, and lead frames. Further, the surface thereof may be further coated with a metal material. This material is not particularly limited, and may be, for example, silver alone, an alloy of silver and copper, gold, aluminum, rhodium, or the like, or a multilayer film using these silver or each alloy. Further, as a method of arranging the metal material, a sputtering method, a vapor deposition method or the like can be used in addition to the plating method.

(Connecting member 13)
The connecting member is a member for fixing the light emitting element to the substrate or the conductor wiring. As the connecting member, an insulating resin or a conductive member can be used. In the case of flip-chip mounting, a conductive member is used as the connecting member. Specifically, Au-containing alloys, Ag-containing alloys, Pd-containing alloys, In-containing alloys, Pb-Pd-containing alloys, Au-Ga-containing alloys, Au-Sn-containing alloys, Sn-containing alloys, Sn-Cu-containing alloys, Sn- Examples thereof include Cu-Ag-containing alloys, Au-Ge-containing alloys, Au-Si-containing alloys, Al-containing alloys, Cu-In-containing alloys, and mixtures of metals and fluxes.

As the connecting member, a liquid, a paste, or a solid (sheet, block, powder, wire) can be used, and can be appropriately selected depending on the composition, the shape of the substrate, and the like. Further, these connecting members may be formed of a single member, or may be used in combination of several kinds.

(Insulation member 15)
It is preferable that the conductor wiring is covered with an insulating member except for the portion that is electrically connected to the light emitting element and other materials. That is, a resist for insulatingly coating the conductor wiring may be arranged on the substrate, and the insulating member can function as a resist.

When arranging the insulating member, not only for the purpose of insulating the conductor wiring, but also by containing a white filler similar to the underfill material described below, light leakage and absorption are prevented, and a light emitting device is used. It is also possible to increase the light extraction efficiency of.
The material of the insulating member is a material that absorbs less light from the light emitting element, and is not particularly limited as long as it has insulating properties. For example, epoxy, silicone, modified silicone, urethane resin, oxetane resin, acrylic, polycarbonate, polyimide and the like can be used.

(Light emitting element 14)
The light emitting element mounted on the substrate is not particularly limited, and known ones can be used, but in this embodiment, it is preferable to use a light emitting diode as the light emitting element.
As the light emitting element, one having an arbitrary wavelength can be selected. For example, as the blue and green light emitting elements, nitride-based semiconductors (In _x Al _y Ga _1-x-y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1), GaP and ZnSe are used. be able to. Further, as the red light emitting element, GaAlAs, AlInGaP and the like can be used. Further, a semiconductor light emitting device made of a material other than this can also be used. The composition, emission color, size, number, etc. of the light emitting element to be used can be appropriately selected according to the purpose.

Various emission wavelengths can be selected depending on the material of the semiconductor layer and its mixed crystalliteness. It may have positive and negative electrodes on the same surface side, or it may have positive and negative electrodes on different surfaces.

The light emitting device of the present embodiment has a translucent substrate and a semiconductor layer laminated on the substrate. An n-type semiconductor layer, an active layer, and a p-type semiconductor layer are formed in this semiconductor layer in this order, an n-type electrode is formed on the n-type semiconductor layer, and a p-type electrode is formed on the p-type semiconductor layer. ing.

The electrodes of the light emitting element are flip-chip mounted on the conductor wiring on the surface of the substrate via a connecting member, and the surface facing the surface on which the electrodes are formed, that is, the main surface of the translucent substrate is used as the light extraction surface. .. When the surface facing the surface on which the electrode is formed is face-up mounted on the surface of the substrate, the light extraction surface is the surface on which the electrode is formed.

The light emitting element is arranged so as to straddle two conductor wirings separated by positive and negative insulation, and is electrically connected by a conductive connecting member and mechanically fixed. As the mounting method of this light emitting element, in addition to the mounting method using solder paste, for example, a mounting method using bumps can be used. Further, as the light emitting element, it is possible to use a small packaged product in which the light emitting element is sealed with a coating resin or the like, and the shape and structure are not particularly limited.

As will be described later, in the case of a light emitting device provided with a wavelength conversion material, a nitride semiconductor capable of emitting a short wavelength capable of efficiently exciting the wavelength conversion material can be preferably mentioned.

(Underfill 16)
When the light emitting element is flip-chip mounted, it is preferable that an underfill is formed between the light emitting element and the substrate. The underfill contains a filler for the purpose of efficiently reflecting the light from the light emitting element and bringing the coefficient of thermal expansion closer to that of the light emitting element.

The underfill material is not particularly limited as long as it absorbs less light from the light emitting element. For example, epoxy, silicone, modified silicone, urethane resin, oxetane resin, acrylic, polycarbonate, polyimide and the like can be used.

If the filler contained in the underfill is a white filler, the light is more easily reflected, and the light extraction efficiency can be improved. Moreover, it is preferable to use an inorganic compound as a filler. The white color here includes a material that appears white due to scattering even when the filler itself is transparent when there is a difference in refractive index from the material around the filler.

Here, the reflectance of the filler is preferably 50% or more, more preferably 70% or more with respect to the light having the peak wavelength of the light emitting element. In this way, the light extraction efficiency of the light emitting device 100 can be improved. The particle size of the filler is preferably 1 nm or more and 10 μm or less. By setting the particle size of the filler in this range, the resin fluidity as an underfill is improved, and even a narrow gap can be covered without any problem. The particle size of the filler is preferably 100 nm or more and 5 μm or less, and more preferably 200 nm or more and 2 μm or less. Further, the shape of the filler may be spherical or scaly.

It is preferable that the side surface of the light emitting element is not covered with the underfill by appropriately selecting and adjusting the particle size of the filler and the material of the underfill. This is to secure the side surface of the light emitting element as a light extraction surface.

(Coating resin 19)
The coating resin is a member arranged on the light extraction surface side of the light emitting element in order to protect the light emitting element from the external environment and optically control the light output from the light emitting element. The coating resin may directly coat the light emitting element, or may not be directly coated and may pass through an air layer or the like.

As the material of the coating resin, a material such as an epoxy resin, a silicone resin, or a resin in which they are mixed can be used. Of these, it is preferable to select a silicone resin in consideration of light resistance and ease of molding. In particular, when gas barrier properties are required, a phenyl silicone resin is preferable.

The coating resin contains a light diffusing material for diffusing the light from the light emitting element. By having the light diffusing material, the light emitted from the light emitting element is diffused in all directions by the light diffusing material.

In addition to the light diffusing material, the coating resin can be used as a wavelength conversion material such as a phosphor that absorbs light from a light emitting element and emits light having a wavelength different from the output light from the light emitting element, or as a light emitting color of the light emitting element. Correspondingly, a colorant can also be contained.

The coating resin can be formed by compression molding or injection molding so as to cover the light emitting element. In addition, the viscosity of the material of the coating resin can be adjusted and dropped or drawn on the light emitting element to form a convex shape by the surface tension of the material itself.

In the case of the latter forming method, the coating resin can be formed by a simpler method without requiring a mold. Further, as a means for adjusting the viscosity of the coating resin material by such a forming method, in addition to the original viscosity of the material, a light diffusing material, a wavelength conversion material, and a colorant as described above are used to obtain a desired viscosity. It can also be adjusted.

(Light diffuser)
Specific examples of the material of the light diffusing material (light diffusing material 17, light scattering particles 18) include SiO ₂ , Al ₂ O ₃ , Al (OH) ₃ , MgCO ₃ , TiO ₂ , ZrO ₂ , ZnO, and so on. Oxide of Nb ₂ O ₅ , MgO, Mg (OH) ₂ , SrO, In ₂ O ₃ , TaO ₂ , HfO, SeO, Y ₂ O ₃ , CaO, Na ₂ O, B ₂ O ₃ , SnO, ZrSiO _{4 and the} like. Examples thereof include nitrides such as SiN, AlN and AlON, and fluorides such as MgF ₂ , CaF ₂ , NaF, LiF and Na ₃ AlF ₆ . These may be used alone, or various types may be melt-mixed and used as glass or the like. Alternatively, they may be divided into a plurality of layers and laminated.

In particular, the refractive index can be arbitrarily controlled by using glass. The particle size of the light diffusing material can be arbitrarily selected from 0.01 to 100 um. Further, the content of the light diffusing material needs to be adjusted, and cannot be uniquely determined by the volume of the coating resin and the particle size of the light diffusing material.

[Third Embodiment]
4A and 4B are schematic structural views showing an example of the light emitting device of the third embodiment, FIG. 4A is a top view, and FIG. 4B is a cross-sectional view taken along the line III-III of FIG. 4A. The present embodiment is different from the light emitting device 200 according to the second embodiment in that the coating resin 19 contains the wavelength conversion material 20 in addition to the light diffusing material (light diffusing material 17, light scattering particles 18). To do.

That is, the light emitting device 300 according to the third embodiment is excited by the light emitting element 14 that emits the first light, the coating resin 19, the light diffusing material 17, and the first light emitted by the light emitting element 14. It has a wavelength conversion material 20 that emits a second light having a wavelength longer than that of the above light. Further, the light emitting device 300 according to the third embodiment may include light scattering particles 18 if necessary.

In the light emitting device 300, a coating resin 19 containing a light diffusing material 17 and a wavelength conversion material 20 is formed on the upper portion (light extraction surface side) of the light emitting element 14.

The light emitting device 300 is, for example, a white LED, for example, the light emitting element 14 includes a blue LED, and the wavelength conversion material 20 includes a yellow phosphor. In a light emitting device including a blue LED and a yellow phosphor, white light is obtained by mixing the blue light emitted by the blue LED and the yellow light emitted by the wavelength conversion material 20 excited by a part of the blue light emitted by the blue LED. Be done.

In this way, in the light emitting device that realizes a desired emission color by mixing the first light emitted by the light emitting element and the second light emitted by the wavelength conversion material, the first light and the second light are mixed. The emission color changes when the ratio changes. In general, the fluorescence luminous efficiency of the wavelength conversion material decreases as the temperature rises, and when the temperature of the light emitting device rises due to driving or the like, the fluorescence luminous efficiency of the wavelength conversion material decreases. In a light emitting device including a blue LED and a yellow phosphor, when the temperature of the light emitting device rises, the amount of yellow light decreases, the ratio of the amount of blue light to yellow light changes, and the chromaticity of white light shifts to the blue side. Shift (the x and y values of the CIE chromaticity coordinates become smaller).

Also in the light emitting device 300 of the third embodiment, the fluorescence luminous efficiency of the wavelength conversion material 20 decreases as the temperature rises. Therefore, when the temperature of the light emitting device 300 rises due to driving or the like, the fluorescence luminous efficiency of the wavelength conversion material 20 decreases.
However, in the light emitting device 300 of the third embodiment, the refractive index of the coating resin 19, the rate of change in the refractive index, and the refractive index of the light diffusing material are taken into consideration in consideration of the decrease in the luminous efficiency of the wavelength conversion material 20 due to the temperature rise. By setting the content and the light amount ratio (mixing ratio) of the first light emitted by the luminous element and the second light emitted by the wavelength conversion material, the light amount ratio (mixing ratio) is less likely to change.

Specifically, the present inventors pay attention to the following points so that the mixing ratio of the first light and the second light is unlikely to change even when the fluorescence luminous efficiency of the wavelength conversion material 20 decreases. The light emitting device 300 of the third embodiment was configured.
First, when the fluorescence luminous efficiency of the wavelength conversion material 20 decreases due to a temperature rise, if the ratio of the first light that excites the wavelength conversion material 20 is unlikely to change due to the temperature rise, the ratio of the first light is relatively high. Increases and the emission color changes.
In this regard, it is considered that the proportion of the first light that excites the wavelength conversion material 20 increases by increasing the amount of light scattered by the light diffusing material 17 of the first light. That is, when the amount of light scattered by the light diffusing material 17 of the first light is increased, the probability that the first light is irradiated to the wavelength conversion material 20 increases, and the ratio of absorption by the wavelength conversion material 20 increases. The second light can be increased.
Therefore, in the light emitting device 300 of the third embodiment, as the temperature rises, the amount of light scattered by the light diffusing material 17 of the first light increases, and the fluorescence emission efficiency of the wavelength conversion material 20 decreases. The change in emission color is suppressed.

Hereinafter, a more specific description will be given.
First, as shown in FIG. 2, the resin constituting the coating resin 19 has a lower refractive index (has a negative temperature coefficient) as the temperature rises.
On the other hand, when an inorganic substance is used as the light diffusing material 17, the temperature dependence of the refractive index of the light diffusing material 17 is smaller than that of the resin and can be regarded as substantially constant.
Further, the amount of light scattered by the light diffusing material 17 contained in the coating resin 19 increases as the reflectance of the light diffusing material 17 increases, and the reflectance of the light diffusing material 17 increases by refraction of the coating resin 19 and the light diffusing material 17. The larger the rate difference, the larger.

More than,
(A) The refractive index of the coating resin 19 has a negative temperature dependence.
(B) The refractive index of the light diffusing material 17 using an inorganic substance is substantially independent of temperature.
(C) The amount of light scattered by the light diffusing material 17 contained in the coating resin increases as the difference in refractive index between the coating resin 19 and the light diffusing material 17 increases.
In consideration of the above, in the light emitting device 300 of the third embodiment,
The material and light diffusion of the coating resin 19 so that the refractive index (third refractive index n3) of the light diffusing material 17 at room temperature (25 ° C.) is higher than the first refractive index n1 of the coating resin 19 at room temperature (25 ° C.). The material of the material 17 is selected.
In this way, as the temperature rises, the difference in refractive index between the light diffusing material 17 and the coating resin 19 increases.
As a result, as the temperature rises, the amount of light scattered by the light diffusing material 17 of the first light can be increased, and the change in emission color due to the decrease in the fluorescence emission efficiency of the wavelength conversion material 20 can be suppressed. become.
Here, in particular, considering the content of the light diffusing material 17 described later, the third refractive index n3 of the light diffusing material 17 at room temperature (25 ° C.) and the first refractive index n1 of the coating resin 19 at room temperature (25 ° C.) The difference in refractive index between them is preferably 0.01 or more and 0.1 or less, and more preferably 0.02 or more and 0.08 or less.

In the light emitting device of the third embodiment, the content of the light diffusing material 17 with respect to the coating resin 19 changes in temperature in consideration of the refractive index of the coating resin 19, the temperature dependence of the refractive index, and the refractive index of the light diffusing material 17. It is set so that the change in emission color with respect to is small.
For example, when the content of the light diffusing material 17 with respect to the coating resin 19 is increased, the rate of increase in the amount of light scattered by the light diffusing material 17 by the light diffusing material 17 increases with increasing temperature. Further, when the content of the light diffusing material 17 with respect to the coating resin 19 is reduced, the rate of increase in the amount of light scattered by the light diffusing material 17 by the light diffusing material 17 as the temperature rises becomes small.

Therefore, when the effect of suppressing the change in emission color based on the difference in refractive index between the coating resin 19 and the light diffusing material 17 is relatively small, it is desired to increase the content of the light diffusing material 17 with respect to the coating resin 19. It becomes possible to obtain the effect of suppressing the change in the emission color.
Further, when the effect of suppressing the change in emission color based on the difference in refractive index between the coating resin 19 and the light diffusing material 17 is relatively large, it is desired to reduce the content of the light diffusing material 17 with respect to the coating resin 19. It becomes possible to obtain the effect of suppressing the change in the emission color.

For example, as shown in Example 1 described later, a silicone resin having a refractive index of 1.51 at room temperature is used as the coating resin 19, and a glass filler having a refractive index of 1.52 at room temperature is used as the light diffusing material 17. When 5 parts by weight of the glass filler was added to 100 parts by weight of the resin, the effect of suppressing the change in the emission color was obtained, but compared with the case where the glass filler having a refractive index of 1.56 at room temperature was used. Then, the effect of suppressing the change in emission color is small. However, even in such a case, a desired effect of suppressing the change in emission color can be obtained by increasing the amount of the glass filler added to the resin.

As described above, in the light emitting device of the third embodiment, the coating resin is considered in consideration of the refractive index of the coating resin 19, the temperature dependence of the refractive index, and the effect of suppressing the emission color change based on the refractive index of the light diffusing material 17. By adjusting the content of the light diffusing material 17 with respect to 19, it becomes possible to provide a light emitting device whose emission color does not easily change with respect to a temperature change.
If the content of the light diffusing material 17 with respect to the coating resin 19 cannot be increased in order to satisfy other required characteristics, the content of the light diffusing material 17 with respect to the coating resin 19 is set to be small, and then the coating resin 19 is set. By appropriately setting the refractive index and the temperature dependence of the refractive index and the refractive index of the light diffusing material 17, it is possible to provide a light emitting device in which the change in emission color with respect to a temperature change is small.

Case of Containing Light Scattering Particles In the light emitting device of the third embodiment, the coating resin 19 may contain light scattering particles 18.
However, when the light scattering particles 18 are included, the refractive index of the light diffusing material 17 and the refractive index and the refractive index of the coating resin 19 are further considered in consideration of the relationship between the light scattering particles 18 and the coating resin 19. It is necessary to set the temperature dependence of the index and the content of the light diffusing material 17 with respect to the coating resin 19.

For example, a silica filler may be contained in order to impart the thixophilicity required for forming the coating resin 19 in the manufacturing process. This silica filler is a light scattering particle 18 having a light diffusing property.
The refractive index of the light-scattering particles 18 made of the silica filler is 1.46.
For example, when a silicone resin having a refractive index of 1.51 at room temperature is used as the coating resin 19 and light scattering particles 18 having a refractive index of 1.46 are contained in the coating resin 19, the coating resin 19 and the light diffusing material are used. The relationship between the refractive indexes of 17 and the light scattering particles 18 is as shown in FIG.

Focusing on the amount of light scattered by the light-scattering particles 18 contained in the coating resin 19 based on the relationship shown in FIG. 2, the difference in refractive index between the coating resin 19 and the light-scattering particles 18 as the temperature rises. Decreases, and the amount of light diffused by the light-scattering particles 18 decreases as the temperature rises. This tendency is opposite to the tendency of the light diffusing material 17 in which the amount of light diffusing increases as the temperature rises, and the light scattering particles 18 having a refractive index smaller than that of the coating resin 19 are coated on the coating resin 19 over a desired temperature range. When it is contained therein, the effect of suppressing the change in emission color by the light diffusing material 17 is canceled out.

Therefore, when the light scattering particles 18 having a refractive index smaller than that of the coating resin 19 are contained in the coating resin 19, in addition to the decrease in the fluorescence emission efficiency of the wavelength conversion material 20 due to the temperature rise, the light contained in the coating resin 19 is further reduced. The refractive index of each of the light diffusing material 17 and the coating resin 19, the temperature dependence of the refractive index of the coating resin 19, and the light diffusing material contained in the coating resin 19 so as to compensate for the decrease in the amount of light scattered by the scattering particles 18. It is necessary to set the content of 17.

Further, when the light scattering particles 18 having a refractive index higher than that of the coating resin 19 are contained in the coating resin 19 over a desired temperature range, the refraction between the coating resin 19 and the light scattering particles 18 increases as the temperature rises. The rate difference becomes large, and like the light diffuser 17, it works to suppress the change in emission color due to the decrease in the fluorescence emission efficiency of the wavelength conversion material 20. Therefore, in this case, for example, the content of the light-scattering particles 18 in the coating resin 19 may be reduced in consideration of the effect of suppressing the emission color change by the light-scattering particles.

In the light emitting device 300 of the third embodiment, the resin material constituting the coating resin 19 can be arbitrarily selected as long as the above-mentioned relationship with the light diffusing material 17 can be satisfied. For example, the coating resin 19 can be selected. Considering the light extraction efficiency emitted through the coating resin 19, the refractive index (referred to as the first refractive index n1) of the coating resin 19 at room temperature is preferably in the range of 1.48 or more and 1.60 or less. Further, the refractive index of the coating resin 19 at 100 ° C. (referred to as the second refractive index n2) is lower than the first refractive index n1 at room temperature of the coating resin 19, and the refractive index of the first refractive index n1 and the second refractive index n2. The rate difference is preferably 0.0075 or more. By constructing the coating resin 19 with a resin having a refractive index and a difference in refractive index in such a range, the change in emission color can be effectively suppressed by the coating resin 19 containing the light diffusing material 17 having a content usually used. Can be done. Here, the normally used light diffusing material 17 content means that the light diffusing material 17 content is in the range of 2 parts by weight to 15 parts by weight with respect to 100 parts by weight of the resin, and preferably light diffusing. The content of the material 17 is in the range of 3 parts by weight to 10 parts by weight, more preferably 4 parts by weight to 7 parts by weight.

Further, the second refractive index n2 of the coating resin 19 at 100 ° C. is lower than the first refractive index n1 of the coating resin 19 at room temperature, and the difference between the first refractive index n1 and the second refractive index n2 of the coating resin 19. Is preferably 0.03 or less. When the difference in refractive index between the first refractive index n1 and the second refractive index n2 of the coating resin 19 is larger than 0.03, the content of the light diffusing material 17 in the coating resin 19 fluctuates (variation in the content) or The variation in the amount of light diffusion due to the variation in the distribution of the light diffusing material 17 (variation in distribution) in the coating resin 19 becomes large.

In the present specification, the first refractive index n1, the second refractive index n2, and the third refractive index n3 are values at the peak wavelength of the light emitting element 14. The first refractive index n1, the second refractive index n2, and the third refractive index n3 may be obtained by directly measuring at the peak wavelength of the light emitting element 14, or are linear based on two values measured at different wavelengths. It may be obtained by approximation.

The resin satisfying the above-mentioned refractive index condition can be selected from various resins such as an epoxy resin, a silicone resin, or a resin in which they are mixed, and a phenyl-based silicone resin is preferable. In the present specification, the phenyl-based silicone resin refers to a silicone resin containing a phenyl group, and may partially contain an alkyl group such as a methyl group. With the phenyl silicone resin, the refractive index and the temperature dependence of the refractive index can be easily set within a range that satisfies the above-mentioned relationship of the refractive index. The phenyl-based silicone resin has a low gas permeability as compared with other silicone resins such as a methyl-based silicone resin, and is suitable as a coating resin 19 for a light emitting device.

Further, the light diffusing material 17 preferably contains glass particles, whereby a light diffusing material having a desired refractive index can be formed. In the present specification, the glass refers to an amorphous inorganic substance, and may contain partially precipitated crystals.
The glass particles contained in the light diffusing material 17 preferably have a refractive index of 1.50 or more and 1.65 or less at the peak wavelength of the light emitting element, and preferably 1.52 or more and 1.60 or less. It is more preferable to have a refractive index of 1.54 or more and 1.58 or less. By using glass particles having a refractive index in such a range, the emission color due to a decrease in the fluorescence emission efficiency of the wavelength conversion material 20 can be easily combined with the coating resin 19 having the refractive index in the specified range and the temperature coefficient thereof. Can suppress changes in.

Examples of the glass particles having a refractive index of 1.50 or more and 1.65 or less at the peak wavelength of the light emitting element include SiO ₂ , Al ₂ O ₃ , Al (OH) ₃ , MgCO ₃ , and TIO described above. ₂ , ZrO ₂ , ZnO, Nb ₂ O ₅ , MgO, Mg (OH) ₂ , SrO, In ₂ O ₃ , TaO ₂ , HfO, SeO, Y ₂ O ₃ , CaO, Na ₂ O, B ₂ O ₃ , One or more materials selected from oxides such as SnO and ZrSiO ₄ , nitrides such as SiN, AlN and AlON, and fluorides such as MgF ₂ , CaF ₂ , NaF, LiF and Na ₃ AlF ₆ are melt-mixed. Examples thereof include glass particles crushed by. In the third embodiment, particularly, it is preferable to use glass particles comprising the SiO ₂ and _Al 2 _{O 3,} the glass particles, the mixing ratio of SiO ₂ and _Al 2 _{O 3,} and / or, further, _{B 2} By containing at least one selected from the group consisting of O ₃ , CaO, Na ₂ O, ZrO ₂ , SrO, F ₂ , MgO, ZnO, the refractive index is in the range of 1.50 or more and 1.65 or less. Can be set arbitrarily.

As described above, in the light emitting device of the third embodiment, in addition to the wavelength conversion material 20, the coating resin 19 contains a light diffusing material 17 having a higher refractive index than the coating resin 19 at 25 ° C. As a result, at 100 ° C., the difference in refractive index between the coating resin 19 and the light diffusing material 17 becomes large, and the amount of light scattered in the coating resin 19 increases. For example, in a light emitting device including a blue LED and a yellow phosphor as the light emitting element 14 and the wavelength conversion material 20, the probability that the blue light from the light emitting element 14 hits the wavelength conversion material 20 increases, and the amount of yellow light increases. Therefore, the ratio of blue light and yellow light can be controlled, and the change in chromaticity due to temperature can be suppressed.

The change in the emission color (chromaticity) can be expressed by, for example, the amount of change in the x value and the y value of the CIE chromaticity coordinate with respect to the temperature change. The smaller the x-value and y-value of the CIE chromaticity coordinates with respect to the temperature change, the more preferable, and the difference between the x-value of the CIE chromaticity coordinates at 25 ° C. and the x-value of the CIE chromaticity coordinates at 100 ° C. is not particularly limited. However, 0.01 or less is preferable, and 0.005 or less is more preferable. The difference between the y value of the CIE chromaticity coordinates at 25 ° C. and the y value of the CIE chromaticity coordinates at 100 ° C. is not particularly limited, but is preferably 0.01 or less, more preferably 0.005. It is as follows.

Further, within the range of the preferable amount of change in chromaticity, the x value of the CIE chromaticity coordinate at 25 ° C. may be smaller than the x value of the CIE chromaticity coordinate at 100 ° C. By doing so, the chromaticity can be shifted in the direction of increasing the visual sensitivity, and the decrease in the light beam at a high temperature can be suppressed.

In the present specification, the difference between the values of the CIE chromaticity coordinates is an absolute value unless otherwise specified. In addition, the light distribution and chromaticity are measured by a photometric method according to JIS standards.

In the third embodiment, an example containing the light-scattering particles 18 is also shown, but the light-scattering particles 18 are not always necessary, and may be added for the purpose of imparting tincture, for example.

(Wavelength conversion material 20)
The wavelength conversion material 20 may be, for example, a material that absorbs light from a light emitting element having a nitride semiconductor as a light emitting layer and converts the wavelength into light having a different wavelength. As the fluorescent substance, for example, a nitride-based phosphor, an acid-nitride-based phosphor, or the like, which is mainly activated by a lanthanoid-based element such as Eu or Ce, can be used. More specifically, it is preferably at least one or more selected from the following (D1) to (D3).
(D1) The following phosphors mainly activated by lanthanide-based elements such as Eu and transition metal-based elements such as Mn.
Fluorescent materials such as alkaline earth halogen apatite, alkaline earth metal borate halogen, alkaline earth metal aluminate, alkaline earth metal sulfide, alkaline earth metal thiogalate, alkaline earth metal silicon nitride, germanate, etc. D2) The following phosphors that are mainly activated by lanthanoid elements such as Ce.
Fluorescent materials such as rare earth aluminates, rare earth silicates, and alkaline earth metals rare earth silicates (D3) Fluorescent materials such as organic or organic complexes that are mainly activated by lanthanoid elements such as Eu.

Of these, a YAG (Yttrium Aluminum Garnet) -based phosphor, which is a rare earth aluminate phosphor that is mainly activated by a lanthanoid-based element such as Ce in (D2), is preferable. The YAG-based phosphor is represented by a composition formula such as (D21) to (D24) below.
(D21) Y ₃ Al ₅ O ₁₂ : Ce
(D22) (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce
(D23) Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce
(D24) (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce

Further, for example, a part or all of Y may be replaced with Tb, Lu or the like. Specifically, Tb ₃ Al ₅ O ₁₂ : Ce, Lu ₃ Al ₅ O ₁₂ : Ce, or the like may be used. Further, a fluorescent substance other than the above-mentioned fluorescent substance, which has the same performance, action and effect, can also be used.

The particle size of such a phosphor is preferably, for example, about 2.5 to 30 μm.
In addition, in this specification, "particle size" means an average particle diameter, and the value is the F.A. which used the air permeation method. S. S. S. No (Fisher-SubSieve-Sizers-No.).

The wavelength conversion material may be, for example, a so-called nanocrystal or a light emitting substance called a quantum dot. Examples of such a material include nano-sized highly dispersed particles such as semiconductor materials such as II-VI group, III-V group, IV-VI group, and I-III-VI group semiconductors. More specifically, CdSe, core-shell type CdS _X Se _1-X / ZnS, GaP, InAs, InP, GaN, PbS, PbSe, Cu (In, Ga) S ₂ , Ag (In, Ga) S _2, etc. Nano-sized highly dispersed particles can be mentioned. Such quantum dots can have, for example, a particle size of 1 to 100 nm, preferably about 1 to 20 nm (about 10 to 50 atoms). By using quantum dots having such a particle size, internal scattering can be suppressed, and light scattering in the wavelength conversion region can be suppressed.

[Fourth Embodiment]
5A and 5B are schematic structural views showing an example of the light emitting device of the first embodiment, FIG. 5A is a top view, and FIG. 5B is an end view taken along line IV-IV of FIG. 5A.

In the light emitting device 400 according to the fourth embodiment, the coating resin 19 has a cap shape, and the light emitting element 14 and the coating resin 19 are separated from each other via the air layer 21. It is different from the light emitting device 300.

In the light emitting device of the fourth embodiment, the refractive index of the light diffusing material 17, the refractive index of the coating resin 19, and the temperature thereof so that the change in the emission color becomes small with respect to the temperature change, as in the third embodiment. Dependency, the content of the light diffusing material 17 with respect to the coating resin 19 is set. As a result, in the light emitting device according to the fourth embodiment of the structure in which the light emitting element 14 and the coating resin 19 are separated via the air layer 21, the light emitting color can be prevented from changing with respect to the temperature change.

Further, with such a configuration, it is possible to make the optical path length of the first light (for example, blue light) emitted from the light emitting element 14 passing through the coating resin 19 substantially the same in the entire area. As a result, the ratio of exciting the wavelength conversion material 20 with the first light (blue light) is almost the same over the entire region, so that color unevenness can be suppressed. Although the coating resin 19 has a dome shape in the fourth embodiment, it is not limited to this and may be, for example, a flat shape.

[Fifth Embodiment]
FIG. 6 is a cross-sectional view showing an example of the light emitting device 500 of the fifth embodiment.
In the light emitting device 500 according to the fifth embodiment, the coating resin 19 has a convex shape (for example, a substantially semi-long spherical shape or a substantially conical shape), and the height A in the optical axis (L) direction is the bottom surface of the coating resin 19. It differs from the light emitting device 200 according to the second embodiment in that it is formed so as to be longer than the width C. The normal line passing through the center of the light emitting element 14 is defined as the optical axis L.

The coating resin 19 having a length longer in the optical axis (L) direction than the width C of the bottom surface can be formed by dropping a resin containing light-scattering particles 18 to enhance the thixophilicity.

In the light emitting device of the fifth embodiment, the length of the coating resin 19 in the optical axis (L) direction is made longer than the width C of the bottom surface, so that the light emitted from the light emitting element 14 is light-scattering with the light diffusing material 17. The light intensity scattered by the particles 18 and emitted from the light emitting device 500 is substantially proportional to the apparent area ratio of the coating resin 19. As a result, the bat wing type light distribution characteristic as shown in FIG. 7 can be realized.

Further, in the light emitting device of the fifth embodiment, the coating resin 19 may contain the wavelength conversion material 20. In the light emitting device of the fifth embodiment, when the coating resin 19 contains the wavelength conversion material 20, the light diffusing material 17 is used so that the change in emission color becomes small with respect to the temperature change in the same manner as in the third embodiment. By setting the refractive index, the refractive index of the coating resin 19 and its temperature dependence, and the content of the light diffusing material 17 with respect to the coating resin 19, the emission color can be made difficult to change with respect to the temperature change.
Further, in the light emitting device of the fifth embodiment, when the light scattering particles 18 are included, the refractive index and coating of the light diffusing material 17 are taken into consideration in consideration of the relationship between the refractive indexes of the light scattering particles 18 and the coating resin 19. It is preferable to set the refractive index of the resin 19 and the temperature dependence of the refractive index, and the content of the light diffusing material 17 with respect to the coating resin 19.

[Sixth Embodiment]
FIG. 8 is a cross-sectional view showing an example of the light emitting device 600 of the sixth embodiment.
The light emitting device 600 of the sixth embodiment is different from the light emitting device 300 of the third embodiment in that the substrate 11 is formed by firing a plurality of laminated ceramic green sheets.

In the light emitting device of the sixth embodiment, the refractive index of the light diffusing material 17, the refractive index of the coating resin 19, and the temperature thereof so that the change in the emission color becomes small with respect to the temperature change, as in the third embodiment. Dependency, the content of the light diffusing material 17 with respect to the coating resin 19 is set. As a result, in the light emitting device according to the sixth embodiment, the light emitting color can be prevented from changing with respect to the temperature change.
Further, in the light emitting device of the sixth embodiment, when the light scattering particles 18 are included, the refractive index and coating of the light diffusing material 17 are taken into consideration in consideration of the relationship between the refractive indexes of the light scattering particles 18 and the coating resin 19. It is preferable to set the refractive index of the resin 19 and the temperature dependence of the refractive index, and the content of the light diffusing material 17 with respect to the coating resin 19.

The substrate 11 has a recess. The recess has an open upper surface and a side surface and a bottom surface. A conductor wiring 12 as an electrode is arranged on the bottom surface of the recess so as to be exposed, and is electrically connected to each of the light emitting elements 14. Further, the recess is sealed with a coating resin 19 containing a light diffusing material 17 and light scattering particles 18. By arranging the light emitting element 14 in the recess of the substrate 11, it is possible to further protect from stress applied from the outside.

In the light emitting device of the first to sixth embodiments described above, the wavelength conversion material 20 may be distributed so as to be contained more on the light emitting element 14 side than on the light extraction surface side of the light emitting device, or may emit light. The light emitting element 14 side may be distributed so as to be smaller than the light extraction surface side of the apparatus.
Further, in the light emitting device of the first to sixth embodiments described above, the light diffusing material 17 may be distributed so as to be contained more on the light emitting element 14 side than on the light extraction surface side of the light emitting device. , The light emitting element 14 side may be distributed so as to be smaller than the light extraction surface side of the light emitting device.

[7th Embodiment]
FIG. 9 is a cross-sectional view showing an example of the light emitting device 700 of the seventh embodiment.
In the light emitting device 700 of the seventh embodiment, the light emitting element 14 is covered with the coating resin 19a containing the wavelength conversion material 20, and the coating resin 19a containing the wavelength conversion material 20 (first coating resin portion). The coating resin 19 (second coating resin portion) b containing the light diffusing material 17 and the light scattering particles 18 on the light extraction surface side (that is, the outside) of the light emitting device 700 is separate from the coating resin 19a (wavelength conversion). It differs from the light emitting device 600 according to the sixth embodiment in that it is formed (separated into a layer containing the material 20 and a layer containing the light diffusing material 17 and the light scattering particles 18).
The coating resin 19b may contain light-scattering particles 18 as required, or may contain only the light diffusing material 17.

That is, the coating resin 19 is divided into two or more layers, and the distance between the layer of the coating resin 19a contained in the wavelength conversion material 20 and the light emitting element 14 is the layer of the coating resin 19b contained in the light diffusing material 17. The configuration is shorter than the distance between the light emitting element 14 and the light emitting element 14.

However, the coating resin 19b containing both the light diffusing material 17 and the light scattering particles 18 does not have to be formed independently. That is, at least the light diffusing material 17 or the light scattering particles 18 need to be distributed in a large amount in a portion away from the light emitting element 14.

Further, the resin material constituting the coating resin 19b containing the light diffusing material 17 or the light scattering particles 18 and the resin material constituting the coating resin 19a containing the wavelength conversion material 20 may be formed of the same material. However, it may be formed of another material.

In the light emitting device of the seventh embodiment described above, the refractive index of the light diffusing material 17, the refractive index of the coating resin 19b and its temperature dependence, and the temperature dependence of the coating resin 19b so that the change in emission color becomes small with respect to the temperature change. The content of the light diffusing material 17 is set. As a result, in the light emitting device according to the seventh embodiment, it is possible to make it difficult for the light emitting color to change with respect to a temperature change.
Further, in the light emitting device of the seventh embodiment, when the light scattering particles 18 are included, the refractive index and coating of the light diffusing material 17 are taken into consideration in consideration of the relationship between the refractive indexes of the light scattering particles 18 and the coating resin 19b. It is preferable to set the refractive index of the resin 19b and the temperature dependence of the refractive index, and the content of the light diffusing material 17 with respect to the coating resin 19.

[Example 1]
The light emitting device according to the first embodiment will be examined. The light emitting device according to the first embodiment is an example of the light emitting device 300 according to the third embodiment. FIG. 4B is a cross-sectional view showing an example of the light emitting device 300. FIG. 10 is a diagram showing CIE chromaticity coordinates in the temperature change of Example 1. The value of the refractive index in the examples is a value at 25 ° C. unless otherwise specified.

As the configuration of the first embodiment, a blue LED having a peak wavelength of 450 nm is used for the light emitting element 14, and a green phosphor (YAG) and a red phosphor (SCASN) are used for the wavelength conversion material 20. As a result, white light having a correlated color temperature of 2700 K was controlled. Further, the coating resin 19 is provided with a silicone resin having a refractive index of 1.51 (25 ° C., wavelength 589 nm), and the light scattering particles 18 (low refractive index) are provided with a silica filler having a refractive index of 1.46 (25 ° C., wavelength 589 nm). Has. Then, apart from the light scattering particles 18, there are three types of refractive indexes: 1.48 (25 ° C., wavelength 589 nm), 1.52 (25 ° C., wavelength 589 nm), and 1.56 (25 ° C., wavelength 589 nm). The temperature is changed from -40 ° C to 130 ° C (-40 ° C, 0 ° C, 25 ° C, 60 ° C, 105 ° C) in a total of four types, one in which the glass filler is contained in the coating resin 19 and the other in which the glass filler is not contained. , 130 ° C.), and the change in chromaticity was confirmed. Here, the glass filler corresponds to the light diffusing material 17 in the third embodiment. The refractive index of the silicone resin at wavelengths of 450 nm and 25 ° C., the refractive index of the silica filler at wavelengths of 450 nm and 25 ° C., and the refractive index of the glass filler at wavelengths of 450 nm and 25 ° C. are, for example, measurements of the refractive index at 589 nm and 25 ° C. It can be obtained by linear approximation based on the value and the measured refractive index at 486 nm and 25 ° C., and based on the measured refractive index at 486 nm and 25 ° C. and the measured refractive index at 435 nm and 25 ° C. It can also be obtained by linear approximation. The refractive indexes calculated by these linear approximations are as follows.
Here, the glass filler 1 shown below is a glass filler having a refractive index of 1.48 (25 ° C., wavelength 589 nm), and the glass filler 2 is a glass filler having a refractive index of 1.52 (25 ° C., wavelength 589 nm). Yes, the glass filler 3 is a glass filler having a refractive index of 1.56 (25 ° C., wavelength 589 nm).
Refractive index of silicone resin: 1.52 (wavelength 450 nm, 25 ° C)
Refractive index of silica filler: 1.47 (wavelength 450 nm, 25 ° C)
Refractive index of glass filler 1: 1.49 (25 ° C, wavelength 450 nm)
Refractive index of glass filler 2: 1.53 (25 ° C, wavelength 450 nm)
Refractive index of glass filler 3: 1.57 (25 ° C, wavelength 450 nm)
In Example 1, the glass filler was contained in an amount of 5 parts by weight based on 100 parts by weight of the resin component of the coating resin 19.

According to Example 1, it was confirmed that the change in emission color can be reduced by incorporating the glass filler (light diffusing material 17) having a refractive index higher than that of the coating resin 19 in the coating resin 19.
Further, as shown in FIG. 10, when the content of the glass filler is 5 parts by weight with respect to 100 parts by weight of the coating resin, the chromaticity increases as the refractive index increases in the light diffusing material having a refractive index higher than that of the coating resin 19. It can be seen that the change is small. The refractive index of the light diffusing material 17 and the content of the light diffusing material 17 are optimized based on the volume and shape of the light scattering particle coating resin 19 in addition to the difference in refractive index from the coating resin and the like. is necessary.

[Example 2]
The light emitting device according to the second embodiment will be examined. The light emitting device according to the second embodiment is an example of the light emitting device 300 according to the third embodiment. FIG. 4B is a cross-sectional view showing an example of the light emitting device 300. FIG. 11 is a diagram showing CIE chromaticity coordinates in the temperature change of Example 2.

In Example 2, the content of the light diffusing material 17 contained in the coating resin 19 was changed, and the content dependence of the emission color suppressing effect was evaluated. Specifically, the content of the glass filler (light diffusing material 17) having a refractive index of 1.56 is set to 3 parts by weight, 5 parts by weight, 10 parts by weight, and 15 parts by weight with respect to 100 parts by weight of the coating resin. The four types of light emitting devices were prepared and the temperature was changed from -40 ° C to 130 ° C (-40 ° C, 0 ° C, 25 ° C, 60 ° C, 105 ° C, 130 ° C), and the change in chromaticity was confirmed.
The configuration of the light emitting device other than the configuration related to the light diffusing material 17 is the same as that of the first embodiment.

From Example 2, the light emitting device having a light diffusing material 17 containing 10 parts by weight and 15 parts by weight with respect to 100 parts by weight of the coating resin has a large amount of blue component when the temperature is low, and a blue component as the temperature rises. Is decreasing and the yellow component is increasing. On the other hand, in the light emitting device having a light diffusing material 17 content of 3 parts by weight with respect to 100 parts by weight of the coating resin, the yellow component is large when the temperature is low, and the yellow component is reduced as the temperature is high to produce a blue component. There are many.
As described above, the content of the light diffusing material 17 is 10 parts by weight with respect to 100 parts by weight of the coating resin, and the content of the light emitting device and the light diffusing material 17 of 15 parts by weight is 3 parts by weight with respect to 100 parts by weight of the coating resin. The direction of change of the color component with respect to temperature is different from that of the light emitting device of.
Further, in the light emitting device in which the content of the light diffusing material 17 is 10 parts by weight with respect to 100 parts by weight of the coating resin, the amount of change in the blue component and the yellow component is changed to 100 parts by weight of the coating resin. On the other hand, it is smaller than the light emitting device of 15 parts by weight.
The reason for such a result is that when the content of the light diffusing material is increased, the interface between the coating resin 19 and the light diffusing material 17 increases and the amount of light scattering increases. That is, the blue light scattered at a high temperature excessively excites the wavelength conversion material 20 and the yellow component becomes too large, which greatly exceeds the amount of decrease in the fluorescence efficiency due to the temperature of the wavelength conversion material 20. From these facts, it can be seen that it is necessary to control not only the difference between the refractive index of the glass filler and the refractive index of the coating resin but also the amount of addition in order to suppress the amount of change in chromaticity.

[Example 3]
The light emitting device according to the third embodiment will be examined. The light emitting device according to the third embodiment is an example of the light emitting device 300 according to the third embodiment. FIG. 4B is a cross-sectional view showing an example of the light emitting device 300. FIG. 12A is a diagram showing CIE chromaticity coordinates in the temperature change of Example 3. FIG. 12B is a diagram showing a luminous flux in the temperature change of Example 3.

Example 3 is carried out in that a yellow-green phosphor (LAG phosphor) and a red phosphor (SCASN) are used as the wavelength conversion material 20 and the blending amount is controlled to obtain white light having a correlated color temperature of 5000 K. It is different from Example 1. Further, in Example 3, a light emitting device containing 5 parts by weight of a glass filler having a refractive index of 1.56 with respect to 100 parts by weight of the coating resin and a light emitting device containing no glass filler were produced and evaluated. Other than that, the same as the light emitting device of Example 1 was used. For these two types of light emitting devices, change the temperature from -40 ° C to 130 ° C (-40 ° C, 0 ° C, 25 ° C, 60 ° C, 105 ° C, 130 ° C) and confirm the change in chromaticity and the change in luminous flux. did.

From Example 3, it was confirmed that even if the correlated color temperature of white light was changed from 2700 K to 5000 K, the change in chromaticity could be suppressed by adding the light diffusing material 17 as in Example 1. Further, when observing the temperature change of the luminous flux, it can be seen that the decrease in the luminous flux at high temperature can be suppressed by adding the light diffusing material 17. It is considered that the main reason for this is that when the light diffusing material 17 is not present, it shifts to the high color temperature side where the visual sensitivity is low at high temperature.

The light emitting device of the present invention can be used as a backlight source for a liquid crystal display, various lighting fixtures, and the like.

100, 200, 300, 400, 500, 600, 700 Light emitting device 11 Base 12 Conductor wiring 13 Connecting member 14 Light emitting element 15 Insulating member 16 Underfill 17 Light diffusing material 18 Light scattering particles 19 Coating resin 20 Wavelength conversion material 21 Air Layer L optical axis

Claims (15)

Light emitting element and
The coating resin that covers the light emitting element and
The wavelength conversion material contained in the coating resin and
The light diffusing material contained in the coating resin and
Light-scattering particles contained in the coating resin and
It is a light emitting device having
The light diffusing material and the light scattering particles include glass particles.
The first refractive index n1 at 25 ° C. at the peak wavelength of the light emitting element of the coating resin is 1.48 or more and 1.60 or less.
The second refractive index n2 of the coating resin at 100 ° C. at the peak wavelength of the coating resin is lower than the first refractive index n1, and the difference in refractive index between the first refractive index n1 and the second refractive index n2 is 0. .0075 and above,
The third refractive index n3 of the light diffusing material at 25 ° C. at the peak wavelength of the light diffusing material is higher than the first refractive index n1.
A light emitting device characterized in that the fourth refractive index n4 of the light scattering particles at 100 ° C. at the peak wavelength of the light scattering particles is lower than the second refractive index n2 . The light emitting device according to claim 1, wherein the difference in refractive index between the first refractive index n1 and the third refractive index n3 is 0.01 or more and 0.1 or less. The light emitting device according to claim 1 or 2, wherein the coating resin contains a phenyl silicone resin. The light emitting device according to any one of claims 1 to 3, wherein the difference in refractive index between the first refractive index n1 and the second refractive index n2 is 0.025 or less. The light emitting device according to any one of claims 1 to 3, wherein the third refractive index n3 of the light diffusing material is 1.50 or more and 1.65 or less. The light emitting device according to any one of claims 1 to 5, wherein the glass particles include SiO ₂ and Al ₂ O ₃ . The light emitting device according to claim 6, wherein the glass particles further include at least one selected from the group consisting of B ₂ O ₃ , CaO, Na ₂ O, ZrO ₂ , SrO, F ₂ , MgO, and ZnO. The light emitting device according to any one of claims 1 to 7, wherein the difference between the x values of the CIE chromaticity coordinates between 25 ° C. and 100 ° C. is 0.01 or less. The light emitting device according to any one of claims 1 to 8, wherein the difference between the x values of the CIE chromaticity coordinates between 25 ° C. and 100 ° C. is 0.005 or less. The light emitting device according to any one of claims 1 to 9, wherein the difference between the y values of the CIE chromaticity coordinates between 25 ° C. and 100 ° C. is 0.01 or less. The light emitting device according to any one of claims 1 to 10, wherein the difference between the y values of the CIE chromaticity coordinates between 25 ° C. and 100 ° C. is 0.005 or less. The light emitting device according to any one of claims 1 to 11, wherein the x value of the CIE chromaticity coordinates at 25 ° C. is smaller than the x value of the CIE chromaticity coordinates at 100 ° C. The light emitting device according to any one of claims 1 to 12, wherein the light scattering particles are made of a silica filler . The coating resin is located on the light emitting element side and includes a first coating resin portion containing the wavelength conversion material and a second coating resin portion containing the light diffusing material and located on the light extraction surface side of the light emitting device. The light emitting device according to any one of claims 1 to 13, which includes. The light emitting device according to any one of claims 1 to 13, wherein the wavelength conversion material is contained in a larger amount on the light emitting element side than on the light extraction surface side of the light emitting device in the coating resin.

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