JP2018006704A - Light-emitting device and illumination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device which reduces decrease in volume of a reflective member and suppresses color non-uniformity of light distribution even if used for a long time.SOLUTION: A light-emitting device comprises: a substrate; a light-emitting element which is mounted on the substrate; a wavelength conversion member which is disposed on a top face of the light-emitting element; a transparent member which fills the surroundings of the light-emitting element and covers at least a part of a side face of the light-emitting element; and a reflective member which is disposed on the transparent member so as to fill the surroundings of the wavelength conversion member. The reflective member covers at least an entire side face of the wavelength conversion member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device, and particularly to a light emitting device including a reflective member that reflects light emitted from a light emitting element around the light emitting element.

  Light-emitting devices using light-emitting elements are used in various lighting devices such as headlamps, street lamps, backlights, displays, and general lighting. In such a light emitting device, in order to obtain light of a desired color such as white light, a combination of a light emitting element and a phosphor as a wavelength conversion material is frequently used.

  Patent Document 1 discloses a light emitting element mounted on a substrate, a phosphor plate adhered on the light emitting element via a light guide member that guides light of the light emitting element, and a space around the light emitting element. And a partition disposed on a substrate. The inside of the screen is filled with a reflective member such as white resin. The white resin covers from the side surface of the phosphor plate to the side surface of the light emitting element, prevents leakage of blue light emitted from the side surface, and improves the incidence of blue light on the phosphor plate.

  Patent Document 2 discloses a light-emitting device including a light-emitting element mounted on a substrate and a phosphor plate bonded onto the light-emitting element through an adhesive that guides light of the light-emitting element. Yes. The side surface of the light emitting element is covered with a first reflective member, and the side surfaces of the first reflective member and the phosphor plate are covered with a second reflective member. White resin or the like is used for the first and second reflective members. By forming the reflective member in such a two-layer structure and applying the adhesive after forming the first reflective member, the light emitting device described in Patent Document 2 is a case where the amount of the adhesive is large. Further, the side surface of the light emitting element can be prevented from being covered with the protruding adhesive. Thereby, the propagation of light in the side surface direction due to the sticking out of the adhesive can be prevented, and the amount of light incident on the phosphor plate can be increased.

JP 2010-219324 A JP 2010-192629 A

However, when the light emitting element and the light emitting element covering the periphery of the phosphor plate with a reflective member are made of a resin in which titanium dioxide particles are dispersed as the reflective member, the reflective member is formed by the photocatalytic property of the titanium dioxide particles. This causes a problem that the resin to be decomposed is decomposed and the volume of the reflective member is reduced. Therefore, a technique is generally used in which the volume of the reflective member is prevented from decreasing by using a crystal system having no photocatalytic property as the titanium dioxide particles. However, when the light-emitting device is used for a long time, the volume of the reflective member may be reduced even if crystalline titanium dioxide particles having no photocatalytic property are used, although the reason is unknown. When the volume of the reflective member is reduced, the side surface of the phosphor plate is partially exposed, and light with a large amount of fluorescent component is emitted from the side surface, which differs from the chromaticity of the light directly above the light emitting element. Become light. This problem of color unevenness appears remarkably in a light-emitting device that uses light with a wide emission angle.
In addition, in the case where a bonding wire is used to electrically connect the light emitting element and the substrate, when the volume of the reflective member is reduced, the bonding wire is exposed and the bonding wire cannot be protected.

  An object of the present invention is to provide a light-emitting device in which the volume of a reflective member is small even when used for a long time and the color unevenness of light distribution is suppressed.

  In order to solve the above problem, a light emitting device of the present invention is filled around a light emitting element, a light emitting element mounted on the substrate, a wavelength conversion member disposed on the upper surface of the light emitting element, The transparent member which covers at least one part of the side surface of a light emitting element, and the reflective member arrange | positioned so that the circumference | surroundings of a wavelength conversion member may be filled on a transparent member are included. The reflective member covers at least the entire side surface of the wavelength conversion member.

  According to the present invention, even when it is used for a long time, the volume of the reflective member is reduced little, and uneven color distribution can be suppressed.

(A) is a top view of a light emitting device as an example of this embodiment, (b) is a diagram for explaining the outline of the AA ′ cross-sectional structure of (a), the emission angle, and a part of the top surface of the transparent member. FIG. 1B is an enlarged view of a part and a diagram for explaining an optical path (A) Cross-sectional view of a conventional light-emitting device provided with a reflective member single-layer structure, (b) The cross-sectional structure, emission angle, and light of the light-emitting device of (a) in which the thickness of the reflective member is reduced by long-term use Diagram explaining the course of Sectional drawing of the part by which the bonding wire of the light-emitting device of this embodiment is not arrange | positioned The figure explaining other examples of the thickness of the reflective member in the light-emitting device of this embodiment, and a part of upper surface of a transparent member The figure explaining the result of the color unevenness in external appearance observation, chromaticity difference, and lamp light distribution in this embodiment and the conventional light emitting device in a tabular format

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, components having the same function are given the same reference numerals, and repeated description thereof is omitted.

  A configuration according to the light emitting device 1 of the present embodiment will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 1 and FIG. 2, the light emitting device 1 of the present embodiment is mainly arranged on a substrate 2, a light emitting element 3 mounted on the substrate 2, and an upper surface of the light emitting element 3. The space around the wavelength converting member 4 and the light emitting element 3 is filled, the transparent member 5 covering at least a part of the side surface of the light emitting element 3, and the space around the wavelength converting member 4 is filled on the transparent member 5. And a reflective member 6 arranged to do so. The reflective member 6 covers at least the entire side surface of the wavelength conversion member 4.

  As described above, the light emitting device 1 has a two-layer structure in which the transparent member 5 is disposed under the reflective member 6 that covers the side surface of the wavelength conversion member 4. It becomes thinner than the case where the periphery of the wavelength conversion member 4 is filled only with a reflective member (see FIG. 3A). Therefore, when the reduction ratio of the volume of the reflective member caused by long-time use is the same regardless of the thickness, the amount of reduction of the reflective member 6 is a light emitting device having a reflective member single-layer structure (FIG. 3A). Smaller. Further, the transparent member 5 hardly decreases even when used for a long time. Therefore, since the total reduction amount of the reflective member 6 and the transparent member 5 can be reduced, the state in which the side surface of the wavelength conversion member 4 is covered with the reflective member 6 can be substantially maintained even when used for a long time. Therefore, it is possible to prevent the emission of the light 24 having a large ratio of wavelength-converted light from the side surface of the wavelength conversion member 4, and even when using light having a wide emission angle, the chromaticity and the emission angle of the light 31 directly above the light emitting element 3. It is possible to suppress the occurrence of color unevenness in the chromaticity of the light 32 having a large θ.

  Moreover, although the light 26 emitted from the side surface of the light emitting element 3 is incident on the transparent member 5, since the reflective member 6 is disposed on the transparent member 5, it is reflected by the reflective member 6 and the wavelength conversion member 4. It is not emitted upward from the surroundings. Alternatively, even if the light is emitted, it is reflected multiple times by the reflective member 6 and the output is considerably reduced, so that the color unevenness does not occur.

  As described above, the light emitting device 1 of the present embodiment can reduce the angle dependency of chromaticity even when used for a long time, and as a result, can prevent uneven color in the light distribution of the emitted light.

  As a comparative example, the light-emitting device having a single-layer structure of the reflective member shown in FIG. 3A selects crystalline reflective particles that are not photocatalytic when used for a long time as shown in FIG. 3B. Even if used, the volume of the reflective member 6 is reduced, and a part of the side surface of the wavelength conversion member 4 is exposed. For this reason, the chromaticity of the light 24 emitted from the exposed side surface is different from the chromaticity of the light 31 directly above the light emitting element 3, and the light distribution is uneven.

  With reference to FIGS. 1 to 4, the configuration of the present embodiment will be further described in detail.

  The light emitting device 1 of the present embodiment includes a mounting substrate 7 on which the substrate 2 is mounted, and a partition member 8 in addition to the above-described substrate 2, light emitting element 3, wavelength conversion member 4, transparent member 5, and reflective member 6. And comprising. The partition member 8 is disposed on the mounting substrate 7 with a space on the side surface of the light emitting element 3. The wavelength conversion member 4 is bonded onto the light emitting element 3 through the adhesive layer 9. The transparent member 5 is filled between the side surface of the light emitting element 3 and the partition member 8 and covers at least a part of the side surface of the light emitting element 3. In the example of FIG. 1B, the transparent member 5 covers the entire side surface of the light emitting element 3. The reflective member 6 is disposed on the transparent member 5 so as to fill a space between the side surface of the wavelength conversion member 4 and the partition member 8. The light emitting element 3 and the substrate 2 are electrically connected by a bonding wire 10.

In order to prevent the uncured transparent member 5 from creeping up on the side surface of the wavelength conversion member 4, the upper end of the transparent member 5 on the side surface of the light emitting element 3 is located on the side surface of the wavelength conversion member 4 as shown in FIG. 4. It is preferable to be located below the lowest part. In consideration of the adhesive layer 9, the upper end of the transparent member 5 is preferably positioned below the upper surface of the adhesive layer 9. Further, in the portion where the bonding wire 10 is connected to the upper surface of the light emitting element 3, the upper end of the transparent member 5 on the side surface of the light emitting element 3 is positioned at least below the uppermost part of the side surface of the light emitting element 3 as shown in FIG. It is preferable to do so.
Thereby, the whole side surface of the wavelength conversion member 4 can be covered with the reflective member 6.

In addition, the upper surface of the transparent member 5 is positioned below the upper surface of the light emitting element 3 at a position away from the side surfaces of the light emitting element 3 and the wavelength conversion member 4 (see, for example, the portion indicated by the dotted ellipse C in FIG. 1B). It is preferable to do. Thereby, since the thickness of the reflective member 6 can be increased at least at a part of the position away from the side surface of the wavelength conversion member, the light 26 emitted from the side surface of the light emitting element 3 can be prevented from passing through the reflective member 6.
In addition, in this embodiment, it is not restricted to the structure of FIG.1 (b), The structure which decreases monotonously as the thickness of the reflective member 6 leaves | separates from the wavelength conversion member 4 like FIG.

  As the material of the transparent member 5, a material that hardly causes a decrease in volume even when the light emitting device 1 is used for a long time is used. As an example, a transparent resin such as a silicon resin, an epoxy resin, or an inorganic binder can be given.

As the reflective member 6, a material in which reflective particles are dispersed in a resin as a base material is used. As a material for the reflective particles, at least one of titanium oxide, zinc oxide, tantalum oxide, and niobium oxide can be used. In this embodiment, titanium oxide is used as an example.
As the resin material, a resin containing a silicon resin or an inorganic binder can be used. The same resin as the transparent member 5 may be used, or a resin different from the transparent member 5 may be used.
The content of the reflective particles with respect to the resin is set so that the side light emitted from the wavelength conversion member 4 can be reflected and the side light from the light emitting element 3 can be prevented from passing through the reflective member 6. Specifically, the content of the reflective particles with respect to the resin is set to, for example, more than 15% by weight and 35% by weight or less. In addition, when it is less than 15% by weight, the reflection effect is weakened, and the light emitted from the side surface of the wavelength conversion member 4 leaks. On the other hand, if it is 35% by weight or more, the resin used as the binder becomes too hard and cracks are generated.

  As the light emitting element 3, a desired element such as an LED element, an LD element, and an EL element can be used. As an example, an LED element that emits blue light having a predetermined wavelength is used.

  As the material for the adhesive layer 9, a material having transparency to the light emitted from the light emitting element 3 is used. Transparent resins such as silicon resin, epoxy resin, and inorganic binder can be used.

  The wavelength conversion member 4 includes a sheet-like or plate-like member formed of a resin or inorganic substance in which a phosphor is dispersed, a phosphor plate composed of a phosphor or a sintered body of a phosphor and another inorganic compound, and Any of plate members made of fluorescent glass can be used. As the phosphor, one that converts light emitted from the light emitting element 3 into fluorescence having a desired wavelength is used. For example, a YAG phosphor or a SiAlON phosphor is used. As the resin, for example, a silicon resin or an epoxy resin is used. In the present embodiment, a YAG phosphor-containing phosphor plate is used as an example.

  In such a light emitting device 1, when power is supplied to the light emitting element 3 through the wiring pattern of the mounting substrate 7 and the substrate 2 and the bonding wire 10, the light emitting element 3 emits light (blue light) 25 and 26 from the upper surface and side surfaces. Emits light. A part of the light 25 from the upper surface passes through the adhesive layer 9 and enters the wavelength conversion member 4, and a part of the blue light is converted into yellow fluorescence 22 by the phosphor, and yellow fluorescence is converted from the upper surface of the wavelength conversion member 4. Mixed light (white light) 23 with blue light is emitted upward. The light 24 emitted from the side surface of the wavelength conversion member 4 is reflected by the reflective member 6 and returned into the wavelength conversion member 4.

  On the other hand, the light 26 from the side surface of the light emitting element 3 enters the transparent member 5, is reflected by the reflective member 6 and the partition member 8, and returns to the light emitting element side. Thus, the light emitting device 1 can prevent the light 26 emitted from the side surface of the light emitting element 3 from passing through the reflective member 6 and being emitted upward from the periphery of the upper surface of the wavelength conversion member 4.

  Moreover, according to this embodiment, since the reduction | decrease of the reflective member 6 can be suppressed, it can prevent that a part of bonding wire 10 is exposed by the reduction | decrease of the reflective member 6. FIG. Thereby, damage to the bonding wire 10 is prevented and the reliability of the light emitting device 1 is increased.

  The mounting method of the light emitting element 3 and the board | substrate 2 can also apply the mounting method of a face down type or a face up type other than the method mentioned above.

  Next, a method for manufacturing the light emitting device 1 of the present embodiment will be described.

(Step 1: Light emitting element mounting process)
A substrate 2 made of AlN ceramics or the like having circuit wiring patterned with Au or the like is prepared, and a back electrode of the light emitting element 3 and a circuit pattern on the substrate 2 are bonded to a predetermined position on the substrate 2 with a bonding material 11 such as AuSn. Use to join. If there is a concern about the flux of the bonding material, the flux may be cleaned. Next, the light emitting element 3 and the wiring pattern of the substrate 2 are wire-bonded with a bonding wire 10 made of gold or the like so that power can be supplied.

(Step 2: wavelength conversion member placement step)
A transparent resin such as silicon resin is applied to the surface of the light emitting element 3 as the adhesive layer 9. After that, the phosphor plate to which the YAG phosphor is added is mounted on the adhesive layer 9 as the wavelength conversion member 4 and heat bonded.
Next, the substrate 2 on which the wavelength conversion member 4 is arranged is mounted on a predetermined position of the mounting substrate 7 on which the circuit wiring is patterned using an adhesive material 12 such as silicon resin. Thereafter, the substrate 2 and the mounting substrate 7 are wire-bonded with a bonding wire (not shown) made of gold or the like so that power can be supplied.

(Step 3: Transparent member placement process)
A partition member 8 having a ring shape and a height equivalent to that of the wavelength conversion member 4 is disposed at a predetermined position on the mounting substrate 7 by bonding with an adhesive. The material of the partition member 8 is ceramic. Next, a predetermined amount of uncured transparent member 5 such as silicon resin is filled into the partition member 8 by a potting method. At this time, the transparent member 5 is prevented from creeping up on the side surface of the wavelength conversion member 4. When the side surface of the wavelength conversion member 4 is wetted, light propagates from the portion adhering to the side surface into the transparent member 5, resulting in a loss of light and a decrease in light taken into the wavelength conversion member 4 and a decrease in luminous flux. The amount of the transparent member 5 only needs to be applied to at least a part of the side surface of the light emitting element 3. Actually, when the transparent member 5 is filled to the same height as the upper surface of the adhesive layer 9, the transparent member 5 is spread and spreads to the height above the partition member 8, so that the surface of the transparent member 5 has a concave shape (FIG. 1). (See (b)). As for the filling amount, it is desirable that a part of the surface of the transparent member 5 (refer to a part indicated by a dotted ellipse D in FIG. 5) has the same height as the upper surface of the adhesive layer 9 at the maximum. Thereafter, the transparent member 5 is cured by heating or the like under predetermined conditions.

(Step 4: Reflective member placement step)
Next, a resin paste in which a predetermined amount of titanium oxide is dispersed in a resin such as a silicon resin is prepared as the reflective member 6. In the same manner as the transparent member 5, the prepared resin paste is filled in the partition member 8 by the potting method so that the reflective member 6 does not crawl up on the upper surface of the wavelength conversion member 4. Further, when the transparent member 5 has a recessed shape, the recess is also filled with the reflective member 6. Thereafter, the reflective member 6 is cured by heating or the like under predetermined conditions.

  In the transparent member arrangement process described above, the case where the ceramic ring is used as the partition member 8 has been described. However, the partition member 8 may be manufactured using a reflective resin or the like instead of the ceramic ring. Further, the transparent member 5 and the reflective member 6 may be formed by a printing method instead of the potting method.

  The light emitting device manufactured according to the above manufacturing method was subjected to a high temperature and high humidity current test as a reliability test. Further, as a comparative example, a conventional light emitting device shown in FIG. 3A was manufactured in the same manner as in the example except that the transparent member 5 was changed to the reflective member 6.

<High temperature and high humidity current test>
Each light emitting device was continuously turned on for 2000 hours in an environment of 85 degrees and humidity of 85%.

<Appearance observation>
The appearance of the reflective member of each light emitting device was visually observed. The result is shown in FIG.
As shown in FIG. 6, there was almost no decrease in the reflective member 6 of the light emitting device of the example. On the other hand, in the light emitting device of the comparative example, the volume of the reflective member 6 is greatly reduced, and a part of the side surface of the wavelength conversion member 4 is exposed.

<Chromaticity difference>
The light-emitting element 3 of the light-emitting device was caused to emit light, and the light emission chromaticity was measured from the direction directly above the light-emitting element 3 (normal direction) and the direction inclined by 80 degrees from the direction directly above, and the chromaticity difference was evaluated. As a result, as shown in FIG. 6, the chromaticity difference between the direction directly above the example and the direction inclined obliquely by 80 degrees was small, but the chromaticity difference of the comparative example was large.

<Color unevenness in light distribution>
Each light emitting device was put in a lamp, and the color unevenness in the lamp light distribution was visually confirmed.
As a result, as shown in FIG. 6, no color unevenness was observed in the light emitting device of the example, but color unevenness was observed in the light emitting device of the comparative example.

  From the above results, the light emitting device 1 of the present invention has a two-layer structure in which the transparent member 5 is provided under the reflective member 6 that covers the side surface of the wavelength conversion member 4, thereby reducing the volume of the reflective member 6. The amount could be suppressed from the comparative example. As a result, it is possible to suppress the deterioration of the bonding wire protection function due to the decrease in the volume of the reflective member, and to suppress the emission of light with high chromaticity from the side surface of the wavelength conversion member 4, thereby suppressing the color unevenness of the lamp light distribution. did it.

  The light emitting device 1 of the present embodiment can be used as an in-vehicle light source and a general illumination light source. In particular, it is suitable for an illuminating device that emits light in an angle range of 80 degrees or more from a direction directly above the light emitting device 1.

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device, 2 ... Board | substrate, 3 ... Light emitting element, 4 ... Wavelength conversion member, 5 ... Transparent member, 6 ... Reflective member, 7 ... Mounting board, 8 ... screen members, 9 ... adhesive layer, 10 ... bonding wire

Claims (8)

A substrate,
A light emitting device mounted on the substrate;
A wavelength conversion member disposed on an upper surface of the light emitting element;
A transparent member filled around the light emitting element and covering at least a part of a side surface of the light emitting element;
A reflective member disposed on the transparent member so as to fill the periphery of the wavelength conversion member;
The light-emitting device, wherein the reflective member covers at least the entire side surface of the wavelength conversion member. The light-emitting device according to claim 1,
An upper end of the transparent member on a side surface of the light emitting element is located below a lowermost portion of the side surface of the wavelength conversion member. The light-emitting device according to claim 1 or 2,
The light-emitting device, wherein the reflective member is obtained by dispersing at least one of titanium oxide, zinc oxide, tantalum oxide, and niobium oxide in a resin. The light emitting device according to any one of claims 1 to 3,
Between the light emitting element and the wavelength conversion member, an adhesive layer transparent to the light emitted from the light emitting element is disposed, and the upper end of the transparent member on the side surface of the light emitting element and the adhesive layer is bonded to the light emitting element. A light-emitting device, which is located below the upper surface of the layer. The light-emitting device according to any one of claims 1 to 4,
A part of the upper surface of the transparent member at a position away from the side surfaces of the light emitting element and the wavelength conversion member is located below the upper surface of the light emitting element. The light-emitting device according to any one of claims 1 to 5,
In the case where the light emitting device includes a bonding wire that electrically connects the light emitting element and the substrate, the upper ends of the transparent members on the side surfaces of the light emitting element and the wavelength conversion member are at least the outermost side surfaces of the light emitting element. A light-emitting device, which is located below the upper part. A mounting board;
A substrate mounted on the mounting substrate;
A light emitting device mounted on the substrate;
A wavelength conversion member disposed on an upper surface of the light emitting element via an adhesive layer;
On the mounting substrate, a partition member disposed with a space on the side surface of the light emitting element,
A transparent member that is filled between the side surface of the light emitting element and the partition member and covers at least a part of the side surface of the light emitting element;
A reflective member disposed on the transparent member so as to fill a space between the side surface of the wavelength conversion member and the partition member;
The light-emitting device, wherein the reflective member covers at least the entire side surface of the wavelength conversion member.   An illuminating device using the light emitting device according to any one of claims 1 to 7 to emit light in an angle range of 80 degrees or more from a direction directly above the light emitting device.

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