JP2010263152A - Reflective light emitting diode - Google Patents

Abstract

The present invention provides a reflective light emitting diode capable of outputting light with uniform intensity by scattering light on a reflective surface.
A support body 6 made of a liquid crystal polymer and having a concave reflecting surface 2 inside, and a light emitting element 10 disposed at an upper central portion of the reflecting surface with a light emitting surface facing the reflecting surface. When a liquid crystal polymer is used for the support, the reflective surface becomes a surface with moderate roughness due to micro unevenness, so that the light emitted from the light emitting element is scattered by the reflective surface, and the emitted light is light of uniform intensity. It becomes.
[Selection] Figure 1

Description

  The present invention relates to a surface-mounted reflective light-emitting diode mounted on the surface of a printed circuit board or the like.

  A reflective light emitting diode having a light emitting element and a support having a concave reflecting surface fixed to the light emitting element and reflecting the light emitted from the light emitting element at the reflecting surface and outputting the light to the outside It is known (see, for example, Patent Document 1). When the support of the reflective light emitting diode is formed of a material such as polyether ether ketone (PEEK) resin, the concave bottom surface of the reflective surface can be finished to a highly smooth surface.

  However, in order to output light of uniform intensity from the reflective light emitting diode, it is effective that the light is scattered to some extent on the reflecting surface. For this reason, it is preferable that the surface of the reflecting surface has an appropriate roughness, that is, has irregularities. When PEEK resin is used for the support, there is a problem that the mirror surface is too smooth and light is not scattered on the reflecting surface, and the light output from the reflective light emitting diode does not have a uniform intensity.

Japanese Patent No. 3968235

  In view of the above problems, an object of the present invention is to provide a reflective light emitting diode capable of outputting light with uniform intensity by scattering light on a reflecting surface.

  According to one aspect of the present invention, a support body made of a liquid crystal polymer and having a concave reflecting surface therein, and a light emitting element arranged with the light emitting surface facing the reflecting surface at an upper central portion of the reflecting surface, A reflective light emitting diode is provided.

  According to the present invention, it is possible to provide a reflection type light emitting diode capable of outputting light with uniform intensity by scattering of light on a reflection surface.

It is a perspective view which shows the structure of the reflection type light emitting diode which concerns on the 1st Embodiment of this invention. It is the bottom view which looked at the light emitting element mounting part of the reflection type light emitting diode which concerns on the 1st Embodiment of this invention from the bottom. 3A and 3B are external views of the light-emitting element used in the first embodiment of the present invention. FIG. 3A is a front view of the light-emitting element, and FIG. 3B is a side view of the light-emitting element. It is an equivalent circuit schematic of the light emitting element used for the 1st Embodiment of this invention. It is a perspective view of the support body of the reflection type light emitting diode which concerns on the 1st Embodiment of this invention. It is sectional drawing along the VI-VI direction of the reflection type light emitting diode shown in FIG. 1 is a partially cutaway plan view of a lead frame used in manufacturing a reflective light emitting diode according to a first embodiment of the present invention. It is process drawing for demonstrating the manufacturing method of the reflection type light emitting diode which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the structure of the reflection type light emitting diode which concerns on the 2nd Embodiment of this invention. It is the bottom view which looked at the light emitting element mounting part of the reflection type light emitting diode which concerns on the 2nd Embodiment of this invention from the bottom.

  Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  As shown in FIG. 1, the reflective light emitting diode 1 according to the first embodiment of the present invention is composed of a liquid crystal polymer, a support 6 having a concave reflective surface 2 inside, and an upper center of the reflective surface 2. The first electrode lead 7 having an anode connection arm 7a extending horizontally from the first portion toward the first wall surface 61 of the support 6 and the first wall surface 61 of the support 6 from the upper central portion of the reflection surface 2 are opposed to each other. The second electrode lead 8 having the cathode connection arm 8a extending horizontally toward the second wall surface 62, the anode electrode electrically connected to the tip of the anode connection arm 7a, and the tip of the cathode connection arm 8a and the electricity And a light emitting element 10 having a cathode electrode connected to the light emitting surface and disposed at the upper central portion of the reflecting surface 2 with the light emitting surface facing the reflecting surface 2.

  The support 6 is formed of a liquid crystal polymer as a single body. “Liquid crystal polymer” is a thermoplastic resin having regularity in a molten state and exhibiting liquid crystal-like properties. The structure of the liquid crystal polymer is basically unchanged even when solidified. For this reason, a molded article having a regular molecule can be obtained without molding change such as shrinkage. Examples of the liquid crystal polymer that can be used for the support 6 include polycondensates of ethylene terephthalate and parahydroxybenzoic acid, polycondensates of phenol and phthalic acid and parahydroxybenzoic acid, 2,6-hydroxynaphthoic acid and para And polycondensates with hydroxybenzoic acid.

  When the liquid crystal polymer is cured by casting into a convex mold in order to perform a mirror finish of the parabolic concave curved surface formed on the upper surface side of the support 6, as much as when PEEK resin is used for the support 6. The parabolic concave surface does not become a smooth mirror surface. That is, the parabolic concave curved surface becomes a surface state having an appropriate roughness due to micro unevenness. When the parabolic concave curved surface is rough, the reflective surface 2 after silver or aluminum is deposited on the parabolic concave curved surface is also rough. That is, when PEEK resin is used for the support 6, the reflective surface 2 becomes almost perfect mirror surface, whereas when the liquid crystal polymer is used for the support 6, the reflective surface 2 is moderate due to micro unevenness. It becomes a rough surface.

  For this reason, by using a liquid crystal polymer for the support 6, the light emitted from the light emitting element 10 is scattered when reflected by the reflecting surface 2, and the scattered light is output to the outside of the reflective light emitting diode 1. The As a result, the light L output from the reflective light emitting diode 1 becomes light of uniform intensity.

  The light emitting element 10 shown in FIG. 1 has a light emitting surface that emits light and an electrode surface 100 that faces the light emitting surface. On the electrode surface 100, an anode electrode in contact with the tip of the anode connection arm 7a and a cathode electrode in contact with the tip of the cathode connection arm 8a are disposed.

  FIG. 2 shows a state in which the light emitting element 10 is mounted on a pair of leads including the first electrode lead 7 and the second electrode lead 8. FIG. 2 is a view of the mounting location of the light emitting element 10 as viewed from the reflective surface 2 side. The light emitting element 10 has the first electrode lead with the light emitting surface 110 that emits light directed toward the reflective surface 2 of the support 6. 7 and the second electrode lead 8. In FIG. 2, the anode electrode 101 and the cathode electrode 102 are indicated by broken lines through the light emitting element 10. The anode electrode 101 is in contact with the tip of the anode connection arm 7a, and the cathode electrode 102 is in contact with the tip of the cathode connection arm 8a. That is, in the reflective light emitting diode 1 shown in FIG. 1, the anode electrode and the cathode electrode of the light emitting element 10 are in direct contact with the first electrode lead 7 and the second electrode lead 8, respectively, and bonding wires are used. Absent.

  As the light emitting element 10, for example, a box-type light emitting diode (LED) chip in which a light emitting unit 11 and a fluorescent light emitting unit 12 are stacked as shown in FIGS. 3A to 3B can be adopted. . An anode electrode 101 and a cathode electrode 102 are formed on one main surface of the light emitting unit 11, and a fluorescent light emitting unit 12 having a configuration in which a phosphor is mixed into a resin or a configuration in which a phosphor is applied to glass is disposed on the other main surface. Has been.

  For example, a blue light emitter that outputs blue light having a wavelength of about 470 nm is used for the light emitting portion 11, and a yellow phosphor such as yttrium, aluminum, garnet (YAG) is used for the fluorescent light emitting portion 12. When a predetermined voltage is applied between the anode electrode 101 and the cathode electrode 102, blue light is output from the light emitting unit 11. The blue light is incident on the fluorescent light emitting unit 12 of the yellow phosphor, and the light L transmitted through the fluorescent light emitting unit 12 is emitted from the light emitting element 10 as white light.

  As shown in FIG. 4, it is effective to employ a configuration in which a light emitting diode 10a that emits light L and a protective element 10b are connected in parallel to the light emitting element 10 to protect the light emitting diode 10a. As the protection element 10b, a Zener diode or the like connected in reverse parallel to the light emitting diode 10a can be used.

  As shown in FIGS. 1 and 2, the first electrode lead 7 has an anode connection arm 7a, a wide lead side surface portion 71 and a wide lead bottom surface portion 72, and the second electrode lead 8 includes a cathode connection arm 8a, A wide lead side surface portion 81 and a wide lead bottom surface portion 82 are provided. The wide lead side surface portion 71 and the wide lead side surface portion 81 are disposed along the wall surface of the support body 6, and the wide lead bottom surface portion 72 and the wide lead bottom surface portion 82 are disposed along the bottom surface of the support body 6. That is, the first electrode lead 7 and the second electrode lead 8 are each bent along the outer surface of the support 6.

  As shown in FIG. 5, the support 6 has a groove 31 formed in the upper part of the first wall surface 61 in the surrounding wall portion 3 surrounding the concave reflecting surface 2, and faces the first wall surface 61. The groove 32 is formed in the upper part of the second wall surface 62.

  As shown in FIG. 1, the anode connection arm 7 a of the first electrode lead 7 is fitted into the groove 31, and the cathode connection arm 8 a of the second electrode lead 8 is fitted into the groove 32. Further, in the groove 31 of the support 6, a dam 301 is formed so as to block the step from the upper surface of the fitting portion of the first electrode lead 7 to the upper edge surface of the support 6. Similarly, a dam 302 is formed in the groove 32 of the support 6 so as to block the step from the upper surface of the fitting portion of the second electrode lead 8 to the upper edge surface of the support 6. The weirs 301 to 302 are formed, for example, by filling and curing a UV curable resin in a stepped portion. Thereby, the base part of the anode connection arm 7a and the cathode connection arm 8a is fixed.

  Further, a transparent epoxy resin such as a cationic polymerization type transparent epoxy resin or a transparent resin 14 such as a transparent silicon resin is filled in the recesses of the support 6 to a depth reaching the upper edge surface of the support 6 and cured. Let Thereby, the light emitting element 10, the anode connection arm 7a, and the cathode connection arm 8a are fixed in a state of being buried in the transparent resin 14.

  The wide lead bottom surface portion 72 of the first electrode lead 7 and the wide lead bottom surface portion 82 of the second electrode lead 8 arranged on the bottom surface of the support 6 are connected to a wiring pattern on a printed circuit board (not shown). Then, the reflective light emitting diode 1 is surface-mounted on the printed circuit board. For example, the wide lead bottom surface portion 72 and the wide lead bottom surface portion 82 are connected to the printed circuit board using solder or the like. Thereby, in order to output the light L from the reflective light emitting diode 1, a predetermined voltage can be applied between the first electrode lead 7 and the second electrode lead 8 through the wiring pattern on the printed circuit board.

  As shown in FIG. 6, most of the light L emitted from the light emitting element 10 is directed downward and reflected by the reflecting surface 2 having a parabolic curved surface. After being reflected by the reflecting surface 2, the light L becomes a substantially parallel light beam and is emitted from the upper surface of the support 6 in a direction perpendicular to the upper surface. For this reason, the light L emitted from the reflective light emitting diode 1 is light having a strong directivity with a uniform orientation compared to a light emitting diode or the like having a bullet-shaped light emitting surface. Therefore, according to the reflective light emitting diode 1, it is possible to obtain light with high luminance at the position where the light L is irradiated.

  Further, no bonding wire is used to connect the light emitting element 10 to the first electrode lead 7 and the second electrode lead 8. For this reason, the light emitted from the light emitting element 10 is not blocked by the bonding wire or the like.

  As described above, in the reflective light emitting diode 1 according to the first embodiment of the present invention, the light L scattered on the reflective surface 2 is reflected by using the liquid crystal polymer for the support 6. 1 is output. As a result, the light L output from the reflective light emitting diode 1 shown in FIG. 1 becomes light of uniform intensity.

  Further, in the reflective light emitting diode 1 shown in FIG. 1, heat generated in the light emitting element 10 is external to the reflective light emitting diode 1 through the wide lead side surface portions 71 and 81 arranged along the outer surface of the support 6. Heat is dissipated. For this reason, the thermal resistance of the reflective light emitting diode 1 can be reduced, and the light emitting element 10 can be energized with a large current. Therefore, there is an advantage that the output of the reflective light emitting diode 1 can be increased.

  A method for manufacturing the reflective light-emitting diode 1 according to the first embodiment of the present invention will be described with reference to FIGS. 7 and 8A to 8D. In addition, the manufacturing method of the reflection type light emitting diode 1 described below is an example, and it is needless to say that it can be realized by various other manufacturing methods including this modified example.

  In mass production, as shown in FIG. 7, a lead frame 20 formed such that a large number of first electrode leads 7 and second electrode leads 8 are arranged side by side on both sides is used. Specifically, a highly conductive material, for example, containing 98% to 99% of copper (Cu) as a main component, including some iron (Fe) and sulfur (S), and further silver-plated to a thickness of 2 μm to 6 μm. The lead frame 20 is formed by etching or punching on a thin plate to which is applied.

  In the lead frame 20, a stress relief hole for relaxing the bending stress is formed in a portion corresponding to the boundary between the portion that becomes the wide lead side surface portion 71 and the portion that becomes the wide lead bottom surface portion 72 of the first electrode lead 7. May be. Similarly, a stress relief hole may be formed in a portion corresponding to the boundary between the portion that becomes the wide lead side surface portion 81 and the portion that becomes the wide lead bottom surface portion 82 of the second electrode lead 8.

  In FIG. 7, flat elliptical holes 21, 22 formed at positions corresponding to the ends of the wide lead bottom surface portion 72 of the first electrode lead 7 and the wide lead bottom surface portion 82 of the second electrode lead 8. Is for reducing the cutting resistance when the cutting process is performed at the break lines 23 and 24.

  In the lead frame 20, the light emitting element 10 is mounted on the anode connection arm 7a and the cathode connection arm 8a as shown in FIG. For example, the anode electrode 101 of the light emitting element 10 is fixed to the front end portion of the anode connection arm 7a with silver paste, and the cathode electrode 102 of the light emitting element 10 is fixed to the front end portion of the cathode connection arm 8a with silver paste.

  8A to 8D show a procedure for attaching each pair of first electrode lead 7 and second electrode lead 8 of the lead frame 20 to the support 6.

  (A) As shown in FIG. 8A, the pair of first electrode lead 7 and second electrode lead 8 on which the light emitting element 10 is mounted are arranged with the light emitting surface 110 of the light emitting element 10 facing the reflecting surface 2. Attach to support 6. At this time, the anode connection arm 7 a of the first electrode lead 7 is fitted into the groove 31, and the cathode connection arm 8 a of the second electrode lead 8 is fitted into the groove 32. As a result, the anode connection arm 7 a and the cathode connection arm 8 a are positioned above the reflecting surface 2 inside the support 6. The wide lead side surface portions 71 and 81 and the wide lead bottom surface portions 72 and 82 are located outside the support 6.

  (B) As shown in FIG. 8B, a weir 301 is formed so as to block the step from the upper surface of the fitting portion of the first electrode lead 7 to the upper edge surface of the support 6, and the second electrode lead The dam 302 is formed so as to block the step from the upper surface of the fitting portion 8 to the upper edge surface of the support 6. As already described, UV curable resin or the like can be used for the weirs 301 to 302.

  (C) As shown in FIG. 8C, a transparent resin 14 such as a high-viscosity transparent epoxy resin or a transparent silicon resin containing a curing catalyst is filled in the concave portion of the support 6 up to its upper edge surface. Thereafter, the transparent resin 14 is cured in an atmosphere furnace at 80 ° C. to 130 ° C. Thereby, the anode connection arm 7 a, the cathode connection arm 8 a, and the light emitting element 10 are integrated with the support 6.

  (D) As shown in FIG. 8 (d), the first electrode lead 7 and the second electrode lead 8 are bent on the portions of the support 6 that are outside. In this bending process, the base portion of the anode connection arm 7 a connected to the portion corresponding to the wide lead side surface portion 71 and the base portion of the cathode connection arm 8 a connected to the portion corresponding to the wide lead side surface portion 81 are connected to the side surface of the support 6. Fold it down along the bottom. Further, the first electrode lead 7 and the second electrode lead 8 are bent inward so that portions corresponding to the wide lead bottom surface portions 72 and 82 are in contact with the bottom surface of the support 6. In this way, each of the first electrode lead 7 and the second electrode lead 8 is bent, and the bending process is completed. When this bending process is completed, the reflection type light emitting diode 1 shown in FIG. 1 is completed. If necessary, the wide lead bottom surface portion 72 of the first electrode lead 7 and the wide lead bottom surface portion 82 of the second electrode lead 8 may be fixed to the bottom surface of the support 6 with solder.

  According to the manufacturing method of the reflection type light emitting diode 1 according to the first embodiment of the present invention as described above, the reflection type light emission in which the light L is scattered on the reflection surface 2 and the light L having a uniform intensity is output. A diode 1 can be provided.

(Second Embodiment)
As shown in FIG. 9, in the reflective light emitting diode 1 </ b> A according to the second embodiment of the present invention, the light emitting element 10 </ b> A mounted on the first electrode lead 70 is connected to the second electrode lead 80 via the bonding wire 901. It is connected. About another structure, it is the same as that of 1st Embodiment.

  That is, the support 6 is made of a liquid crystal polymer and has a concave reflecting surface 2 inside. The light emitting element 10 </ b> A is disposed in the upper center portion of the reflecting surface 2 with the light emitting surface facing the reflecting surface 2. The first electrode lead 70 has an anode connection arm 70 a that extends horizontally from the upper central portion of the reflective surface 2 toward the first wall surface 61, and the second electrode lead 80 is an upper central portion of the reflective surface 2. To a second wall surface 62 of the cathode connection arm 80a extending horizontally.

  The light emitting element 10A is an LED in which an anode electrode and a cathode electrode are disposed on each of a pair of opposed main surfaces, and the main surface on which the cathode electrode is disposed is a light emitting surface. As shown in FIG. 10, the light emitting element 10A is mounted on the first electrode lead 70 so that the anode electrode contacts the tip of the anode connection arm 70a, and the cathode electrode connects the tip of the cathode connection arm 80a and the bonding wire 901. Connected through. For example, the anode electrode of the light emitting element 10A is fixed to the tip of the anode connection arm 70a with silver paste. Next, the cathode electrode of the fixed light emitting element 10A and the cathode connection arm 80a are connected by the bonding wire 901. A gold wire or the like can be used for the bonding wire 901.

  Since the liquid crystal polymer is used for the support 6, the light emitted from the light emitting element 10 </ b> A is scattered when reflected by the reflecting surface 2, and the scattered light is output to the outside of the reflective light emitting diode 1 </ b> A. As a result, the light L output from the reflective light emitting diode 1A becomes light of uniform intensity.

  9 to 10 show an example in which the light emitting element 10A is an LED having a main surface 110A on which a cathode electrode is disposed as a light emitting surface. When the light emitting surface of the light emitting element 10A is the main surface on which the anode electrode is disposed, the light emitting element 10A is mounted on the tip of the cathode connection arm 80a in contact with the cathode electrode of the light emitting element 10A. And the anode electrode of 10 A of light emitting elements is connected with the front-end | tip part of the anode connection arm 70a by the bonding wire.

  As shown in FIG. 10, the first electrode lead 70 and the second electrode lead 80 to which the light emitting element 10A is electrically connected are attached to the support 6 in the same manner as described with reference to FIG. . That is, the anode connection arm 70 a is fitted in the groove 31 of the support 6, and the cathode connection arm 80 a is fitted in the groove 32 of the support 6. After filling the concave portion of the support 6 with the transparent resin 14, the first electrode lead 70 is bent along the outer surface of the support 6, and the wide lead side surface portion 701 is disposed along the first wall surface 61. The lead bottom surface portion 702 is disposed along the bottom surface of the support 6. Similarly, the second electrode lead 80 is bent along the outer side surface of the support body 6, the wide lead side surface portion 801 is disposed along the second wall surface 62, and the wide lead bottom surface portion 802 is formed on the bottom surface of the support body 6. Arrange along.

  The tip ends of the anode connection arm 70 a and the cathode connection arm 80 a shown in FIG. 9 are arranged along a direction parallel to the first wall surface 61 and the second wall surface 62. For this reason, the bonding wire 901 is wired along a direction perpendicular to the extending direction of the anode connection arm 70a and the cathode connection arm 80a. Therefore, the bonding wire 901 is not pulled by a force that separates the tip portion generated during the process of bending the first electrode lead 70 and the second electrode lead 80. As a result, disconnection of the bonding wire 901 during manufacturing can be prevented, and the manufacturing yield of the reflective light emitting diode 1A can be improved. Others are substantially the same as those in the first embodiment, and redundant description is omitted.

  According to the reflective light emitting diode 1A according to the second embodiment of the present invention, when the light emitting element 10A connected to the first electrode lead 70 or the second electrode lead 80 with a bonding wire is used, the reflective surface 2 Scattering of the light L occurs, and the light L output from the reflection type light emitting diode 1A can be made into light of uniform intensity.

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the description of the above-described embodiment, an example in which white light is output by the light emitting element 10 in which the light emitting unit 11 that outputs blue light and the fluorescent light emitting unit 12 that uses yellow phosphor is laminated is shown. By combining various light emitting units 11 and fluorescent light emitting units 12, the color of the light L output from the reflective light emitting diode 1 can be arbitrarily set. Further, the emission color of the light emitting element 10A is not limited.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

L: Light 1, 1A ... Reflective light emitting diode 2 ... Reflecting surface 3 ... Wall 6 ... Support body 7, 70 ... First electrode lead 7a, 70a ... Anode connection arm 8, 80 ... Second electrode lead 8a, 80a ... Cathode connection arm 10, 10A ... Light emitting element 10a ... Light emitting diode 10b ... Protection element 11 ... Light emitting part 12 ... Fluorescent light emitting part 14 ... Transparent resin 31, 32 ... Groove 61 ... First wall surface 62 ... Second wall surface 71, 81 , 701, 801... Wide lead side surface portion 72, 82, 702, 802... Wide lead bottom surface portion 100... Electrode surface 101 .. Anode electrode 102.

Claims (1)

A support made of a liquid crystal polymer and having a concave reflecting surface inside;
A reflective light emitting diode, comprising: a light emitting element disposed at an upper central portion of the reflective surface with the light emitting surface facing the reflective surface.

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