JP4991029B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device capable of multicolor light emission used for light sources such as various pilot lamps, display devices, backlights, and displays, and more particularly to a light emitting device having a high contrast ratio.

  In a large display device using light emitting diodes (hereinafter also referred to as LEDs) of three primary colors of red (R), green (G), and blue (B), these colors are arranged in a matrix, for example, and the respective light emission Full color display can be achieved by combining colors.

  For example, when a surface-mounted LED is used in such a display device, it is known that a light absorption layer is provided on the light emission observation surface of the package excluding the light emitting portion in order to increase the contrast ratio (for example, Patent Documents). 1).

  It is also known to improve the contrast by using a coloring member that is substantially the same as each emission color on the surface of the substrate that reflects the light from the light emitting element (for example, Patent Document 2), and to contain a coloring member in the mold member. (For example, Patent Document 3).

JP 2000-183405 A JP 2000-22221 A JP-A-9-283806

  However, when using a colored member as in Patent Document 2, if the LED itself is small, it is difficult to provide the colored member. In particular, in the case of a multicolor light emitting LED on which RGB semiconductor light emitting elements (hereinafter also referred to as light emitting elements) are mounted, it is difficult to provide different colored members for each light emitting element. The same applies to the case where a colored member is contained in the mold member as described in Patent Document 3. Such a colored member is effective for a single color light emitting LED, but if a single color light emitting LED is used, the display device becomes large and it is difficult to obtain a high-definition image.

  In view of the above, an object of the present invention is to provide a light-emitting device that can provide a high-definition display device with high contrast ratio by reducing dark luminance.

  In order to achieve the above object, a light-emitting device of the present invention includes a plurality of light-emitting elements having different emission wavelengths, a base having a plurality of recesses on which the light-emitting elements are placed, and a sealing member provided in each recess. The recesses are spaced apart from each other, and a sealing member containing a colored member having the same color as the emission wavelength of the light emitting element is provided. Accordingly, a light-emitting device in which light-emitting elements with different emission wavelengths are arranged at high density can be obtained, and thus a display device with a high contrast ratio and capable of displaying a higher-definition image can be obtained. .

  In the light-emitting device according to claim 2 of the present invention, the concave portion is composed of three concave portions having openings having substantially the same shape, and a green light-emitting element, a red light-emitting element, and a blue light-emitting element are mounted on each concave portion. It is characterized by being placed. Accordingly, a light-emitting device that can have a high contrast ratio and a high-definition full-color display can be obtained.

  The light emitting device according to claim 3 of the present invention is characterized in that the base has a black upper surface provided with the recess. Accordingly, a light-emitting device that can be a display device with a higher contrast ratio can be obtained.

  According to the present invention, a light-emitting device capable of realizing a display device with high contrast ratio and high-definition display can be provided.

  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 member shown in the claims as the member of the embodiment. In particular, 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 extent that there is no specific description. It is just an example. It should be noted that the size and positional relationship of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof 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.

  1A shows a front view (top view) of a light-emitting device 100 according to the embodiment, and FIG. 1B shows a cross-sectional view taken along line X-X ′ of FIG. 1A. In the present embodiment, the base 101 of the light emitting device is made of resin, and has three concave portions 101A, 101B, and 101C spaced from each other on the upper surface thereof. In each recess, the conductive member 102 is exposed on the bottom surface, and the conductive member is partially included in the base 101 and provided so as to protrude from the side surface of the base. The protruding conductive member is bent along the bottom surface of the base 101, and functions as a conductor wiring of the light emitting elements 103A, 103B, and 103C disposed on the base. Each light emitting element is fixed on the conductive member 102 by a joining member such as resin or metal paste. The conductive electrode 104 electrically connects the p electrode and the n electrode of each light emitting element to the conductive member. In addition, sealing members 105A, 105B, and 105C such as resin are filled in the respective concave portions of the base 101 so as to seal them.

  In this embodiment, the light emitting elements placed in the recesses 101A (first recess), 101B (second recess), and 101C (third recess) are the green light emitting element 103A, the red light emitting element 103B, The blue light emitting element 103C includes a sealing member 105A containing a green coloring member, a sealing member 105B containing a red coloring member, and a blue coloring member. The sealing member 105 </ b> C is characterized. As described above, the contrast ratio can be further improved by including in the sealing member a colored member having the same color as the emission wavelength of the light emitting element to be mounted.

(Concave)
The recess has an opening on the upper surface (light emission observation surface) side of the substrate, and a light emitting element can be placed on the bottom surface of the recess, and a bonding region such as a wire for conducting with the conductive member is provided. It has a size that can be secured. The depth of the recess needs to be higher than at least the height of the light emitting element, and can be appropriately selected in consideration of optical characteristics such as light distribution characteristics.

  In the present embodiment, there are a plurality of recesses, and the recesses are provided so as to be separated from each other. For example, as shown in FIG. 1A and FIG. 1B, the first concave portion 101A, the second concave portion 101B, and the third concave portion 101C having the same opening shape are arranged so as to be spaced apart at equal intervals. The shape of each recess may be a track shape as shown in FIG. 1A, a circle, an ellipse, a square, a rectangle, other polygons, or a combination of these. In addition, the size of the opening of the recess, the area of the bottom surface, the inclination of the side surface of the recess, and the like can be appropriately selected according to desired light distribution characteristics.

  Moreover, as another form, it can also be set as the shape which has the level | step-difference part 206 on the upper surface of the base | substrate 201 as shown to FIG. 2A and FIG. 2B. The recesses 201A, 201B, and 201C are separated from each other at the bottom of the stepped portion 206, and sealing members 205A, 205B, and 205C containing a colorant having the same color as the emission wavelength of the light emitting elements 203A, 203B, and 203C are provided. . A covering member 207 may be provided on the step portion 206 above each of the recesses. By including a diffusing member or the like in the covering member 207, the color mixing property can be improved. As the covering member, a member similar to a resin used for a sealing member described later can be used.

(Sealing member)
The sealing member is a member that protects a semiconductor light emitting element or a conductive wire mounted on the upper surface of the plate-like base or a base having a concave portion from dust, moisture, external force, etc., and protects light from the light emitting element. What has translucency which can permeate | transmit is preferable. In the present embodiment, the sealing member contains a coloring member having the same color as the emission wavelength of the light emitting element placed in the recess. For example, a sealing member containing a blue coloring member is provided in the recess where the blue light emitting element is placed. Specifically, as shown in FIGS. 1A and 1B, a green light emitting element 103A is placed in the recess 101A, and a sealing member 105A containing a green coloring member is provided. Similarly, a red light emitting element 103B is placed in the recess 101B, a sealing member 105B containing a red colored member is provided, a blue light emitting element 103C is placed in the recess 101C, and a sealing member 105C containing a blue colored member is placed. Is provided. Thus, by providing a sealing member containing a different colored member for each recess, a light-emitting device with a high contrast ratio can be obtained.

  Specific examples of the sealing member include silicone resin, epoxy resin, and urea resin. The filling amount of the sealing member may be an amount that covers a protective element such as a body light emitting element or a Zener diode, and a conductive wire. For example, as shown in FIG. 1B, the sealing members 105A, 105B, and 105C The filling can be performed so as to reach the upper surface of the substrate 101. Moreover, as a sealing member, you may make it laminate | stack the sealing member which does not contain a coloring member with the sealing member containing a coloring member. That is, different sealing members may be laminated instead of filling the entire recess with a single sealing member.

  The sealing member is cured by heating. In this case, the sealing member may be heated at the same time after all the recesses are filled with the sealing member, whereby the curing can be efficiently performed with fewer steps. Or you may pass through several heating processes, such as heating after filling a sealing member in one recessed part, and filling a sealing member in another recessed part, and heating after that. Accordingly, it is possible to reduce a problem that a sealing member containing a colored member of a different color is mixed in an adjacent recess.

(Coloring member)
The coloring member contained in the sealing member has a color tone similar to the emission wavelength of the light emitting element, and examples thereof include pigments and dyes. It is preferable that the sealing member is uniformly dispersed, and a material that hardly inhibits the curing of the sealing member is preferable. Moreover, a thing with the high light transmittance is preferable. In the case of a pigment, it is preferable to use a pigment having a particle size of 3.0 μm or less, preferably 2.5 μm or less and uniformly dispersed in a solvent or the like before being mixed with the sealing member. These are variously selected in consideration of the composition, specific gravity, viscosity and the like of the sealing member to be used, and the addition amount can be appropriately selected according to the purpose and application.

  As long as the pigment satisfies the above conditions, the composition is not particularly limited, and organic pigments, inorganic pigments, and the like can be used. For example, specific examples of organic pigments include phthalocyanine-based and anthraquinone-based pigments as blue pigments. Examples of the green pigment include phthalocyanine-based pigments. Examples of red pigments include perylene, azo lake, quinacridone, pyrrolo-peel, and azo. These can be used singly or in combination depending on the color.

(Substrate and conductive member)
In the present embodiment, the substrate is provided with a conductive member for protecting electronic parts such as a light emitting element and a protective element and supplying an electric current from the outside to the electronic parts. Since the substrate is used as a display device, the substrate is preferably mounted at a high density with an adjacent light emitting device, and preferably has a square shape or a shape close to this. However, it is not particularly limited to this, and may be a triangle, a quadrangle, a polygon, or a shape close to these in a plan view (top view).

  As the base material, an insulating member is preferable, and a member that hardly transmits light from the light emitting element, external light, or the like is preferable. Moreover, what has a certain amount of intensity | strength is preferable, and a ceramic, a phenol resin, a glass epoxy resin, BT resin, PPA, etc. are mentioned more specifically.

  By using ceramic as the substrate, a substrate with high heat resistance can be obtained. As the ceramic, alumina, aluminum nitride, mullite, silicon carbide, silicon nitride or the like is preferable. A ceramic green sheet obtained by molding a ceramic powder and a material obtained by mixing a binder resin into a sheet shape is laminated and fired to obtain a substrate having a desired shape. At this time, by forming and laminating through holes of various sizes on the ceramic green sheet, a substrate having a recess can be obtained. The metal underlayer disposed on the base is fired by applying a conductive paste containing fine particles of a high melting point metal such as tungsten or molybdenum in a predetermined pattern at an unfired ceramic green sheet stage. Can be obtained.

  In addition, as described above, the substrate made of ceramic can be formed by forming the conductive member on a previously fired ceramic plate, in addition to integrally forming the conductive member and the insulating portion.

  In addition, the substrate having the recesses is formed integrally with the substrate constituting the bottom surface and the side surface like the ceramic substrate exemplified above, and the plate substrate (for example, a glass epoxy resin substrate) has a plate shape having a through hole. A base member on which a semiconductor light emitting element can be placed in the recess can be used by attaching a member to the recess.

  Further, when a resin is used as the base material, the resin base can be formed by injection molding or the like by using a lead terminal made of a plate-like metal as the conductive member. In this case, it can be set as the structure similar to the said ceramic base | substrate by providing a coating | coated member after shape | molding so that a lead terminal may be exposed to the bottom face of the recessed part of a base | substrate. In addition, as a specific material of the resin, an insulating member is preferable, and a member that does not easily transmit light from the semiconductor light emitting element or external light is preferable. Further, it has a certain degree of strength, and a thermosetting resin, a thermoplastic resin, or the like can be used. More specifically, a phenol resin, a glass epoxy resin, a BT resin, PPA, or the like can be given.

  As a material for the conductive member (lead terminal), a material using a material having a relatively large thermal conductivity is preferable. By forming with such a material, heat generated in the light-emitting element can be efficiently released. For example, it is preferable to have a thermal conductivity of about 200 W / (m · K) or more. Furthermore, a material having a relatively large mechanical strength or a material that can be easily punched or etched or etched is preferable. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron, nickel, iron-nickel alloys, phosphor bronze, iron-containing copper, and the like.

  Further, the base may be provided with a black member for improving contrast. In that case, the contrast can be improved by making the upper surface (the surface provided with the recesses) at least black. The black member can be easily provided by a method such as applying a black colored member, or the substrate itself may be black. In that case, a white material having a high reflectance can be used for the sidewall of the recess. As the black member, when the base itself is black, a black additive, for example, PPA or ceramic added with carbon can be used, and when it is provided to be applied to the surface of the base, the black member is black. Phenol ink, black epoxy resin, etc. can be used.

(Light emitting element)
A light emitting element having an arbitrary wavelength can be selected. For example, in order to obtain a display device used as a full-color display, light emitting devices of three colors of blue, green, and red are used for the light emitting device. As the blue and green light-emitting elements, those using ZnSe or a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) can be used. As the red light emitting element, GaAs, InP, or the like can be used. Furthermore, a semiconductor light emitting element made of a material other than this can also be used. The composition, emission color, size, number, and the like of the light emitting element to be used can be appropriately selected according to the purpose.

  Further, a light-emitting element that outputs not only light in the visible light region but also ultraviolet rays and infrared rays can be obtained. In addition to the semiconductor light emitting element, a light receiving element, a protective element (for example, a Zener diode or a capacitor) that protects the semiconductor element from destruction due to overvoltage, or a combination thereof can be mounted.

(Die bond member)
The die bond member is a bonding member for mounting a light emitting element, a protection element, or the like on a base body or a conductive member. Either a conductive die bond member or an edge die bond member can be selected depending on the substrate of the mounted element. it can. For example, in the case of a semiconductor light emitting device in which a nitride semiconductor layer is laminated on sapphire, which is an insulating substrate, it can be used either insulating or conductive. When a conductive substrate such as a SiC substrate is used, a conductive die bond Conduction can be achieved by using a member. As the insulating die bond member, an epoxy resin, a silicone resin, or the like can be used. In the case of using these resins, a metal layer having a high reflectance such as an Al film can be provided on the back surface of the semiconductor light emitting element in consideration of deterioration due to light or heat from the semiconductor light emitting element. In this case, a method such as vapor deposition, sputtering, or bonding a thin film can be used. In addition, as the conductive die bond member, a conductive paste such as silver, gold, or palladium, solder such as Au—Sn eutectic, or a brazing material such as a low melting point metal can be used.

(Conductive wire)
The conductive wire that connects the electrode of the semiconductor light emitting element and the conductive member provided on the support is required to have good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the conductive member. 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.

  The light-emitting device according to the present invention is a light-emitting device capable of providing a high-definition display device by increasing the contrast ratio and arranging light-emitting elements capable of emitting light of different wavelengths at high density. A display device, a display, etc. can be used.

FIG. 1A is a front view showing an example of a light emitting device according to the present invention. 1B is a cross-sectional view taken along the line X-X ′ of FIG. 1A. FIG. 2A is a front view showing an example of a light emitting device according to the present invention. FIG. 2B is a cross-sectional view taken along the line Y-Y ′ of FIG. 2A.

Explanation of symbols

100, 200... Light emitting device 101, 201... Base 101A, 201A.
101B, 201B ... concave portion (second concave portion)
101C, 201C... Recess (third recess)
102, 202 ... conductive members 103A, 203A ... light emitting element (green light emitting element)
103B, 203B... Light emitting element (red light emitting element)
103C, 203C ... Light emitting element (blue light emitting element)
104, 204 ... conductive wires 105A, 205A ... sealing member (first sealing member)
105B, 205B ... sealing member (second sealing member)
105C, 205C ... sealing member (third sealing member)
206 ... Step part 206 ... Coating member

Claims (3)

A light-emitting device having a plurality of light-emitting elements having different emission wavelengths, a substrate having a plurality of recesses on which the light-emitting elements are placed, and a sealing member provided in each recess,
The recesses are separated from each other at the bottom of the stepped portion of the base body,
The step portion is provided with a covering member,
The sealing member and the covering member are made of the same resin,
The sealing member contains a colorant having the same color as the emission wavelength of the light emitting element ,
The said coating | coated member contains the diffusion member, The light-emitting device characterized by the above-mentioned .   The light emitting device according to claim 1, wherein the concave portion includes three concave portions having openings having substantially the same shape, and a green light emitting element, a red light emitting element, and a blue light emitting element are placed in each concave portion.   The light emitting device according to claim 1, wherein the base has a black upper surface provided with a recess.

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