JP2007110060A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device which emits light uniformly in high brightness utilizing a light emitting element. <P>SOLUTION: The light emitting device includes: a light emitting element; a wavelength changing member where a fluorescent substance is contained which absorbs at least a part of light from the light emitting element and emits light having a different wavelength; and a supporter having a recess. The recess has: an opening figure similar to the plane figure of the light emitting element; a bottom surface on which the light emitting element is located; and a side wall orthogonal to the bottom surface. At least a part of the wavelength changing member located on the recess reaches the upper surface of the side wall, the depth from the opening of the recess to the bottom surface is 1.2 to 30 times the thickness of the light emitting element, and the space between the side wall of the recess and the side of the light emitting element is 1 to 5 times the thickness of the light emitting element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting device that can be used for a backlight source of a lighting fixture, a display, a liquid crystal display, and the like, and more particularly, to a light-emitting device with high brightness and suppressed light distribution chromaticity unevenness.

  For example, as disclosed in Japanese Patent Laid-Open No. 2005-166937, in a light emitting device including a light emitting element and a fluorescent material, the fluorescent material is contained in a sealing member that covers the light emitting element. The light emitting element is disposed in a concave portion of a support body provided with a conductor wiring for supplying power to the light emitting element. Furthermore, the fluorescent material is contained in the sealing member filled in the recess. More specifically, the side wall of the recess has an inner diameter that increases toward the opening direction of the recess in order to improve the light extraction efficiency from the light emitting element. Such a bowl-shaped recess is filled with a sealing member made of a translucent resin so as to cover the light emitting element. Furthermore, the fluorescent substance is mixed with the material of the sealing member and filled in the recess, and a wavelength conversion member in which the fluorescent substance is bound by the sealing member is formed.

Japanese Patent Application Laid-Open No. 2005-166937.

  However, the arrangement of the fluorescent material in the periphery of the light emitting element is affected by the shape of the sealing member formed by the shape of the recess. Therefore, it is difficult for the conventional light-emitting device to be contained in the sealing member so that the fluorescent material is in a good distribution state in each light emission observation direction. Therefore, a difference occurs in the chromaticity of the light emitting device for each light emission observation direction. In addition, there has been a demand for a light emitting device that can further improve the wavelength conversion efficiency of a fluorescent material and obtain wavelength conversion light with high luminance.

  Accordingly, an object of the present invention is to provide a light emitting device that emits light with high luminance and uniform chromaticity for each light emission observation direction.

  In order to achieve the above object, a light-emitting device according to the present invention includes a light-emitting element, a wavelength conversion member containing a fluorescent material that emits light having a wavelength different from that of the light-emitting element, and a support having a recess. In the light emitting device, the concave portion has an opening shape similar to a planar shape of the light emitting element, and a side wall surface perpendicular to a bottom surface on which the light emitting element is disposed, and a depth from the opening portion to the bottom surface of the concave portion. Is 1.2 to 30 times the thickness of the light emitting element, and the distance between the side wall surface of the recess and the side surface of the light emitting element is 1 to 5 times the thickness of the light emitting element. At least a part of the outermost surface of the wavelength conversion member disposed in the recess reaches the upper surface of the side wall of the recess.

  The light emitting element preferably has a rectangular shape.

  The support is preferably made of ceramics, and the side wall surface of the recess preferably has a metal layer containing at least one metal selected from silver, aluminum, and rhodium.

  It is preferable that the electrode of the light emitting element is connected to a conductor wiring provided outside the concave portion of the support via a conductive wire.

  It is preferable that the light emitting device further includes a translucent member that covers the conductive wire. Furthermore, the translucent member preferably has a convex shape in the emission observation direction.

  The semiconductor element different from the light emitting element is preferably disposed outside the recess in which the light emitting element is disposed.

  The present invention can suppress a chromaticity shift due to a light emission observation direction and can be a high-luminance light-emitting device.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

A light emitting element, a wavelength conversion member containing a fluorescent material that emits light having a different wavelength by absorbing at least part of the light from the light emitting element, and a recess for disposing the light emitting element and the wavelength conversion member The present inventor has made various studies in order to obtain a light emitting device that emits high-luminance light without causing a difference in chromaticity in the light emission observation direction. As a result, the light emitting device having at least the following configurations (A) to (C) is used to solve the above-described problems.
(A) The recess provided in the support is formed of an opening shape similar to the planar shape of the light emitting element, a bottom surface on which the light emitting element is disposed, and a side wall surface perpendicular to the bottom surface.

For example, when the opening shape of the recess is rectangular, the planar shape of the light emitting element is also a rectangle similar to the opening shape. At this time, it is preferable that the major axis direction of the opening shape of the concave portion coincides with the major axis direction of the planar shape of the light emitting element. This is to improve the distribution state of the wavelength conversion member filled in the recesses.
(B) At least a part of the wavelength conversion member covering the light emitting element disposed in the recess reaches the upper surface of the sidewall of the recess.

“At least a part of the wavelength conversion member disposed in the recess reaches the upper surface of the side wall of the recess” means that the entire outermost surface of the wavelength conversion member disposed in the recess is flush with the upper surface of the side wall of the recess. It is not limited to. That is, the wavelength conversion member includes a wavelength conversion member in which the central portion of the outermost surface of the wavelength conversion member is recessed in the direction of the light emitting element and the peripheral portion of the outermost surface of the wavelength conversion member reaches the upper surface of the side wall of the recess. Among these, it is particularly preferable that the outermost surface of the wavelength conversion member arranged in the recess is flush with the upper surface of the sidewall of the recess. This is because the distribution state of the fluorescent substance can be improved by making the outermost surface of the wavelength conversion member flush with the upper surface of the side wall of the recess. This also allows the fluorescent material to be arranged at high density around the light emitting element.
(C) The depth from the opening to the bottom of the recess is 1.2 to 30 times the thickness of the light emitting element, and the distance between the side wall surface of the recess and the side of the light emitting element is the thickness of the light emitting element. 1 to 5 times.

  In order to arrange the fluorescent material at a high density around the light emitting element, the side wall surface of the concave part and the side surface of the light emitting element are formed without increasing the size of the opening shape of the concave part with respect to the size of the planar shape of the light emitting element. Is preferably 1 to 5 times the thickness of the light emitting element. The depth from the opening to the bottom of the recess is more preferably 1.2 to 5 times the thickness of the light emitting element in consideration of further improving the light extraction efficiency. Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a light-emitting device in this embodiment, and FIG. 2 is a cross-sectional view. Moreover, FIG. 4 is the figure which expanded the cross section of the recessed part of the support body in this form.

  As shown in FIG. 4, the thickness t of the light emitting element in this embodiment refers to the height from the bottom surface of the recess where the light emitting element is disposed to the top surface of the light emitting element. Further, the interval between the light emitting element and the side wall of the recess means the distance W between the side surface of the light emitting element disposed in the recess and the side wall surface of the recess. Here, it is assumed that the light emitting element is bonded to the bottom surface of the recess with an adhesive such as resin or eutectic solder. Moreover, the depth D of a recessed part means the perpendicular distance from the bottom face of a recessed part to the side wall upper surface of a recessed part. Moreover, when arrange | positioning a metal layer on the inner wall face of a recessed part, the side wall surface of a recessed part, a bottom face, and a side wall upper surface shall each be the outermost surface of a metal layer. Moreover, it is preferable that the light emitting element is arranged at the center of the recess. This is because the distribution state of the fluorescent material contained around the light emitting element is improved.

  Hereinafter, the effects of the present invention will be described in detail. For example, when the thickness of the light emitting element is the same as the depth of the concave portion, that is, when the upper surface of the side wall of the concave portion and the upper surface of the light emitting element are on the same plane, the wavelength conversion member is disposed in a well distributed state above the light emitting element. I can't. In addition, if the wavelength conversion member is too thick around the light emitting element, the light output of the light emitting device is reduced. Therefore, it is preferable that the wavelength conversion member surrounding the light emitting element is thin. By setting the relationship between the concave portion of the support and the light emitting element to the above-described configurations (A) to (C), the fluorescent substance is concentrated around the light emitting element, so that the wavelength conversion efficiency by the fluorescent substance is improved. Therefore, a light-emitting device that emits light with high luminance can be obtained.

  In addition, by adopting the above-described configurations (A) to (C), the light extraction efficiency is improved and high brightness is achieved without forming a bowl-shaped recess having an inner diameter that increases in the opening direction as in the prior art. And it can be set as the light-emitting device which light-emits uniformly. That is, in order to improve the distribution state of the fluorescent material, if the side wall is perpendicular to the bottom surface of the recess in consideration of the shape of the wavelength conversion member, the light extraction efficiency utilizing the reflection of the side wall is lowered. However, by setting the size of the concave portion having the configuration (C) of the present invention, it is possible to obtain a light emitting device that emits light with uniform chromaticity in each light emission observation direction while improving light extraction efficiency.

  The planar shape of the light emitting element includes all shapes that can be formed in the manufacturing process of the semiconductor element, such as a rectangle and a polygon such as a hexagon. In particular, the planar shape of the light emitting element is preferably a rectangle such as a square or a rectangle. These shapes are because a process for manufacturing a light-emitting element by dividing a semiconductor wafer into individual light-emitting elements is easy, and thus a light-emitting device with high mass productivity can be obtained.

  Further, the support is made of ceramic, and the ceramic base exposed on the side wall surface of the recess is preferably covered with a metal layer containing at least one metal selected from silver, aluminum, and rhodium. . By using such a metal layer containing a highly reflective metal, light passing through porous ceramics is suppressed to improve light extraction efficiency from the light emitting device, and a light emitting device with higher brightness can be obtained. Can do.

  Moreover, it is preferable that the electrode of a light emitting element is connected with the conductor wiring outside a recessed part with the electroconductive wire. That is, the conductive wire of the support is connected to the outside of the recess without providing a region for connecting the conductive wire in the recess. Thereby, the relationship between the recess and the light emitting element can be easily made the configuration of the present invention without considering the region where the conductive wire is wire-bonded in the recess.

  Moreover, it is preferable that the light-emitting device further includes a translucent member that covers the conductive wire. The material of the translucent member can be selected from translucent resins such as epoxy resins and silicone resins, and translucent inorganic members such as glass. Moreover, a translucent member can be formed by various molding methods, such as compression molding, injection molding, or transfer molding, using them as a material. By providing the light-transmitting member in the light-emitting device of this embodiment, the conductive wire exposed to the outside of the concave portion can be protected from the external environment by the light-transmitting member, and a highly reliable light-emitting device can be obtained. . In addition, since the translucent member has a convex shape in the light emission observation direction, the light emitted from the concave portion can be condensed and a light emitting device with high luminance can be obtained. Hereinafter, each structure of this form is explained in full detail.

(Support)
The support in this embodiment is a member that has a recess for mounting a light emitting element and can be arranged with a light reflection wall or a metal layer as a conductor wiring. Therefore, the support body of this embodiment can be a lead frame mainly made of aluminum or iron-containing copper, or a package in which such a lead frame is insert-molded into a resin.

  Examples of the base material in this embodiment include glass epoxy resin, ceramics, and glass. In particular, by using ceramics as a material, a support having high heat resistance can be obtained.

  The ceramic is preferably alumina, aluminum nitride, mullite, silicon carbide or silicon nitride. In particular, 90 to 96% by weight of the raw material powder is alumina, and 4 to 10% by weight of viscosity, talc, magnesia, calcia, silica and the like are added as sintering aids and sintered in a temperature range of 1500 to 1700 ° C. 40-60% by weight of ceramics and raw material powder is alumina, and 60-40% by weight of borosilicate glass, cordierite, forsterite, mullite, etc. are added as sintering aids and sintered in the temperature range of 800-1200 ° C. And ceramic substrates.

  By laminating and firing ceramic green sheets obtained by molding a ceramic powder and a material obtained by mixing a binder resin into a sheet shape, a plate-shaped support can be obtained. Or it can be set as the support body which has a recessed part by forming and laminating | stacking through-hole of various magnitude | sizes in a ceramic green sheet. The first metal underlayer disposed on such a support was coated with a predetermined pattern of conductive paste containing fine particles of a refractory metal such as tungsten or molybdenum at the stage of an unfired ceramic green sheet. It can be obtained by firing. Furthermore, after firing the ceramic green sheet, nickel, gold, or silver can be plated in order on the pre-formed base layer to form a metal layer or conductor wiring disposed on the side surface of the recess.

  As described above, the support made of ceramic material can be formed by arranging the conductor wiring on a pre-fired ceramic plate in addition to integrally forming the conductor wiring and the insulating portion. .

(Light emitting element)
The light emitting element in this embodiment can be a light source of a light emitting device such as a light emitting diode or a laser diode. The support in this embodiment can be equipped with a light-emitting element, a light-receiving element, and a protective element (for example, a Zener diode or a capacitor) that protects these semiconductor elements from destruction due to overvoltage, or a combination thereof.

  In this embodiment, it is preferable that the semiconductor element not covered with the wavelength conversion member is disposed outside the concave portion in which the light emitting element that outputs the irradiation light to the wavelength conversion member is disposed. As such a semiconductor element, for example, a light emitting element that directly uses emitted light as part of light of a light emitting device without converting the wavelength by a wavelength conversion member, or mounted on a support together with the light emitting element of this embodiment. Examples thereof include a light receiving element and a protective element to be obtained. These elements are arranged on the outside of the concave portion without being provided with a region in the concave portion in which the light emitting element for outputting the light to be irradiated to the wavelength conversion member is arranged, and are provided on the support. Connected with wiring. Furthermore, these elements may be arranged in another recess provided outside the recess. Thereby, elements other than the light emitting element that outputs the irradiation light to the wavelength conversion member do not affect the optical characteristics of the light subjected to wavelength conversion by the wavelength conversion member. Therefore, it is not necessary to consider the size of the elements other than the light emitting element that outputs the irradiation light to the wavelength conversion member and the region for die bonding the same for the same recess. For this reason, the configuration of the present invention can be easily set to the relationship between the light emitting element and the concave portion in which the light emitting element that outputs the irradiation light to the wavelength conversion member is disposed.

In this embodiment, an LED chip will be described as an example of a light emitting element. Examples of the semiconductor light-emitting element that constitutes the LED chip include those using various semiconductors such as ZnSe and GaN. However, in the case of a light-emitting device having a fluorescent material, the short-circuit that can efficiently excite the fluorescent material. wavelength capable of emitting nitride semiconductor _{(in X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is preferably exemplified. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. For example, the LED chip can be a light emitting element that outputs not only visible light but also ultraviolet rays and infrared rays.

  The semiconductor element can also be electrically and mechanically connected to a conductor of an auxiliary member called a support or a submount via a conductive material called a bump.

(Conductive wire)
In this embodiment, the conductive wire that connects the electrode of the semiconductor element and the conductor wiring of the support is required to have good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the conductor wiring. Preferably ^{0.01cal / (s) (cm 2} ) (℃ / cm) or higher as heat conductivity, and more preferably ^{0.5cal / (s) (cm 2} ) (℃ / cm) or more. In consideration of workability and the like, the diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less. Specific examples of such conductive wires include conductive wires using metals such as gold, copper, platinum, and aluminum, and alloys thereof. Such a conductive wire can easily connect the wire bonding region formed in the conductor wiring and the electrode of the semiconductor element by a wire bonding apparatus.

(Wavelength conversion member)
The wavelength conversion member in this embodiment is a member containing a fluorescent material that emits light having different wavelengths by absorbing at least a part of light from the light emitting element. Such a wavelength conversion member includes a fluorescent substance, a transparent resin such as an epoxy resin or a silicone resin, which is a binder for fixing the fluorescent substance, and a transparent inorganic member such as glass. The concave portion is filled and molded into a wavelength conversion member.

  The fluorescent material that can be used in this embodiment converts light from the light emitting element, and it is more efficient to convert light from the light emitting element to a longer wavelength. When the light from the light-emitting element is short-wavelength visible light with high energy, YAG: Ce, which is a kind of aluminum oxide phosphor, is preferably used. In particular, the YAG: Ce phosphor absorbs part of the blue light from the LED chip depending on its content and emits yellow light that is a complementary color. Can be formed relatively easily. Note that the fluorescent material can be contained in a translucent member covering the conductive wire in addition to those contained in the wavelength conversion member.

  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.

  FIG. 1 is a perspective view of a light emitting device 100 according to the present embodiment, and FIG. 2 is a cross-sectional view of the light emitting device according to the present embodiment. FIG. 4 is an enlarged view showing the cross section of the recess of this embodiment.

  The light emitting device 100 according to the present embodiment includes a support having a recess for arranging the LED chip 101 and the wavelength conversion member 108, and a conductor in which the electrode of the LED chip 101 die-bonded to the bottom of the recess is applied to the support. A conductive wire 104 for connecting to the wiring 103 and a translucent member 102 covering the wavelength conversion member 108 and the conductive wire 104 are provided.

  The support in this example is obtained by applying conductor wiring to a base material 105 made of ceramics. This conductor wiring is electrically connected from the wire bonding region 103 exposed on the upper surface of the side wall of the recess to the electrode 106 provided on the back side of the support through the through hole provided in the base material 105. ing.

  The LED chip 101 of this embodiment has a square planar shape with a dimension of 600 μm square. The thickness t of the LED chip 101 is 85 μm.

  The opening shape of the concave portion of the support in the present embodiment is a square similar to the planar shape of the LED chip 101. Moreover, this opening shape is the same size and shape from the opening part of a recessed part to a bottom face. Furthermore, a metal layer 107 is disposed on the side wall of the recess so that the outermost surface is silver.

  The depth D of the recess is 102 μm (1.2 times the thickness t), and the interval W between the side surface of the LED chip 101 and the outermost surface of the metal layer 108 is 85 μm (1.0 times the thickness t). is there.

  The wavelength conversion member 107 is formed by filling a concave portion with a mixture in which an aluminum oxide phosphor is contained in a silicone resin. The outermost surface of the wavelength conversion member 108 formed in the recess is flush with the upper surface of the sidewall of the recess.

  According to this embodiment, a chromaticity shift due to the emission observation direction is suppressed, and a light-emitting device with high luminance can be obtained.

  The LED chip 101 of the present embodiment has a square planar shape with a dimension of 800 μm square. The thickness t of the LED chip 101 is 85 μm.

  The opening shape of the concave portion of the support in the present embodiment is a square similar to the planar shape of the LED chip 101. In this embodiment, the depth D of the concave portion is 1360 μm (16 times the thickness t), and the distance W between the side surface of the LED chip 101 and the outermost surface of the metal layer 108 is 212.5 μm (2.5 mm of the thickness t). Times).

  Otherwise, the light emitting device is formed in the same manner as in Example 1. According to this embodiment, a chromaticity shift due to the emission observation direction is suppressed, and a light-emitting device with high luminance can be obtained.

  The LED chip 101 of the present embodiment has a rectangular planar shape with dimensions of 240 μm × 420 μm. The thickness t of the LED chip 101 is 85 μm.

  In this embodiment, the opening shape of the concave portion of the support is a rectangle similar to the planar shape of the LED chip 101. The LED chip 101 is arranged at the center of a rectangular recess bottom similar to the planar shape of the LED chip 101. The depth D of the recess in this example is 2550 μm (30 times the thickness t), and the interval W between the side surface of the LED chip 101 and the outermost surface of the metal layer 108 is 425 μm (5.0 times the thickness t). It is.

  Otherwise, the light emitting device is formed in the same manner as in Example 1. According to this embodiment, a chromaticity shift due to the emission observation direction is suppressed, and a light-emitting device with high luminance can be obtained.

  The LED chip 101 of this embodiment has a square planar shape with a dimension of 600 μm square. The thickness t of the LED chip 101 is 120 μm.

  The opening shape of the concave portion of the support in the present embodiment is a square similar to the planar shape of the LED chip 101. The depth D of the recess is 300 μm (2.5 times the thickness t), and the distance W between the side surface of the LED chip 101 and the outermost surface of the metal layer 108 is 200 μm (1.67 times the thickness t). is there.

  Otherwise, the light emitting device is formed in the same manner as in Example 1. According to this embodiment, a chromaticity shift due to the emission observation direction is suppressed, and a light-emitting device with high luminance can be obtained.

  FIG. 3 is a cross-sectional view of the light emitting device 200 according to this example. In the light emitting device 200 according to the present embodiment, the shape of the translucent member 102 according to the first embodiment is a lens shape convex in the emission observation direction. Thereby, a light-emitting device with high luminance can be obtained.

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

FIG. 1 is a perspective view showing an embodiment of a light emitting device of the present invention. FIG. 2 is a cross-sectional view showing an embodiment of the light emitting device of the present invention. FIG. 3 is a cross-sectional view showing an embodiment of the light emitting device of the present invention. FIG. 4 is an enlarged view showing a cross section of an embodiment of the light emitting device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200 ... Light-emitting device 101 ... Light-emitting element 102 ... Translucent member 103 ... Conductor wiring 104 ... Conductive wire 105 ... Base material 106 ... Electrode 107 ... Metal layer 108 ... wavelength conversion member

Claims (7)

A light-emitting device comprising: a light-emitting element; a wavelength conversion member containing a fluorescent material that emits light having a wavelength different from that of the light-emitting element; and a support having a recess.
The recess has an opening shape similar to the planar shape of the light emitting element and a side wall surface perpendicular to the bottom surface on which the light emitting element is disposed, and the depth from the opening to the bottom surface of the recess is the light emission The thickness of the element is 1.2 to 30 times, and the distance between the side wall surface of the recess and the side surface of the light emitting element is 1 to 5 times the thickness of the light emitting element,
At least a part of the outermost surface of the wavelength conversion member disposed in the recess reaches the upper surface of the side wall of the recess.   The light emitting device according to claim 1, wherein the light emitting element has a rectangular shape.   3. The light emitting device according to 1 or 2, wherein the support is made of ceramics, and the side wall surface of the recess has a metal layer containing at least one metal selected from silver, aluminum, and rhodium.   4. The light emitting device according to claim 1, wherein the electrode of the light emitting element is connected to a conductor wiring provided outside the concave portion of the support via a conductive wire. 5.   The light-emitting device according to claim 4, further comprising a translucent member that covers the conductive wire.   The light-emitting device according to claim 5, wherein the translucent member has a convex shape in a light emission observation direction. The light emitting device according to claim 1, wherein the semiconductor element different from the light emitting element is disposed outside a recess in which the light emitting element is disposed.

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