JP2006156643A - Surface-mounted light-emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounted light-emitting diode capable of securing a wide bonding portion with a solder member and suppressing a mounting space when soldering and mounting, on a mount substrate such as a mother board, a light-emitting diode comprised of a thin substrate such as a flexible substrate. <P>SOLUTION: A surface-mounted light-emitting diode 21 comprises: a thin plate shaped circuit board 22 with a wiring electrodes formed on its front face and with external connecting electrodes 27, 28, conducted with the wiring electrode, formed on its rear face; a light-emitting element 25 mounted approximately in the center of the upper surface of the circuit board 22; and a reflection frame 31 disposed above the circuit board 22 to surround the light-emitting element 25, on the circuit board 22. Electrode extension parts 22c, 22d are integrally formed while extend to the outer peripheral surface of the reflection frame 31 and include, on its rear faces, electrodes conducted with the external connecting electrodes 27, 28. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface-mounted light-emitting diode that can be surface-mounted on a mother board, and more particularly, to a surface-mounted light-emitting diode that includes an external connection electrode portion for stably performing bonding with solder.

  FIG. 7 shows the structure of a typical conventional surface-mounted light emitting diode (see Patent Document 1). This surface-mounted light emitting diode (light emitting diode) 1 is formed by patterning a pair of electrodes (for example, a cathode electrode 3 and an anode electrode 4) on the upper surface of a rectangular glass epoxy substrate (glass epoxy substrate) 2. After the light emitting element 5 is mounted thereon, the upper portion thereof is sealed with resin. These electrodes 3 and 4 go to the back side through through-hole electrodes 6a and 6b provided at both ends of the glass epoxy substrate 2, and the back electrodes 7a and 7b are electrically connected to the printed wirings 9a and 9b provided on the mother board 8. It is supposed to be.

  As shown in FIG. 7, the cathode electrode 3 extends to the central portion 10 on the glass epoxy substrate 2, and the light emitting element 5 is bonded to the central portion 10. In addition, a reflective frame 11 is disposed in the central portion 10 so as to surround the light emitting element 5. The inner surface of the reflecting frame 11 is inclined in a mortar shape, and the light emitted from the light emitting element 5 is reflected on the inner surface and condensed upward.

  The light emitting element 5 is a substantially cubic microchip, and has electrodes on the lower surface and the upper surface, respectively. The lower surface electrode is joined to the cathode electrode 3 in the reflection frame 11 by a solder member 12, and one upper surface electrode is connected to the anode electrode 4 by a bonding wire 13. The light-emitting element 5 is sealed above the glass-epoxy substrate 2 including the reflective frame 11 with a light-transmitting resin material, and light emitted from the light-emitting element 5 is disposed above the resin material. A lens portion 14 for further condensing the light is provided.

  As shown in FIG. 7, the light-emitting diode 1 having the above structure has the back electrodes 7a and 7b placed on the printed wiring electrodes 9a and 9b formed on the mother board 8, and the upper surfaces of the printed wiring electrodes 9a and 9b. A solder member 12 is applied and joined to the side surfaces of the through-hole electrodes 6a and 6b.

Further, in recent light emitting diodes, the material of the circuit board is changing from the glass epoxy substrate shown above to a thin film flexible substrate due to the demand for thinning. According to this flexible substrate, it is possible to perform three-dimensional molding by pressing or the like, and has advantages such as easy processing and low thermal resistance.
JP 2000-261041 A

  However, when the circuit board on which the light emitting element is mounted is configured by a flexible board, the board thickness is very thin compared to the glass epoxy board, so that the solder member cannot be sufficiently applied when surface-mounted on the motherboard. . If the applied amount of the solder member is small, poor conduction is likely to occur, and there is a problem that the yield of the product is lowered or the reliability is lowered due to aging. Further, there is a problem in that it is not easy to confirm the applied shape (solder fillet) of the solder member when inspecting the product.

  In addition, when the light emitting diode constituted by the flexible substrate is mounted so that the light emitting surface is oriented sideways, the bonding surface of the solder member is further narrowed, so that the side light emitting type light emitting diode having sufficient solder bonding strength is provided. It was difficult to realize.

  Accordingly, an object of the present invention is to increase the formation of a solder fillet when mounting a light-emitting diode constituted by a thin substrate such as a flexible substrate on a mounting substrate such as a mother board via a solder member, thereby enabling conductive connection. It is an object of the present invention to provide a surface-mount type light emitting diode capable of improving the reliability and ease of inspection and reducing the mounting space.

  In order to solve the above problems, a surface-mounted light-emitting diode according to the present invention comprises a thin circuit board having a wiring electrode on the front surface and an external connection electrode connected to the wiring electrode on the back surface, and an upper surface of the circuit board. In a surface-mounted light-emitting diode including a light-emitting element mounted at a substantially central portion and a reflection frame body disposed above the circuit board so as to surround the light-emitting element, the circuit board includes The electrode extension part which has an electrode part which extends to the outer peripheral surface of the reflection frame body and is electrically connected to the external connection electrode is integrally formed on the back surface.

  According to the surface mount type light emitting diode according to the present invention, the external connection electrode connected to the mounting substrate such as the mother board via the solder member is extended outward from the outer peripheral surface of the reflecting frame surrounding the light emitting element. In addition, since it is formed over the extended electrode portion, the application surface of the solder member can be widened. As a result, the surface-mounted light-emitting diode can be stably connected to the mounting substrate and the reliability can be improved. In addition, the application shape of the solder member can be easily confirmed.

  In addition, the electrode extension is integrally formed with the circuit board on which the reflection frame is placed, and the electrode extension is bent and fixed to the outer peripheral surface of the reflection frame. It is not necessary to take extra mounting space.

  Furthermore, since the circuit board is formed of a thin flexible board, the electrode extension can be folded and accommodated in a compact manner without reducing conductivity or strength.

  Hereinafter, embodiments of a surface-mounted light emitting diode according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a surface-mounted light-emitting diode (light-emitting diode) 21 according to this embodiment includes a circuit board 22 on which a wiring electrode is formed on the front surface and an external connection electrode that is electrically connected to the wiring electrode is formed on the back surface. The light-emitting element 25 is mounted on the circuit board 22, and the reflection frame 31 is disposed on the circuit board 22 so as to surround the light-emitting element 25.

  For the circuit board 22, a single flexible board having electrode patterns formed on both the front and back sides of a thin film member is used, and the circuit body 22a on which the reflection frame 31 is placed, and the arranged reflection. A pair of electrode extensions 22c and 22d that are bent on the left and right outer peripheral surfaces of the frame 31 are provided. The wiring electrodes on the front surface side are a cathode electrode 23 and an anode electrode 24 formed with a light emitting element 25 mounted at the center of the circuit board 22 as a boundary, and the back surface side is the cathode electrode 23 and the anode electrode 24, respectively. The external connection electrodes 27 and 28 are electrically connected. The cathode electrode 23 and the anode electrode 24 are formed from the circuit main body portion 22a to the electrode extension portions 22c and 22d, and are electrically connected to the external connection electrodes 27 and 28 through the through holes 26, respectively.

  The circuit board 22 is formed with a pedestal portion 22b in which a substantially central portion of the circuit main body portion 22a is pressed from the rear surface side to protrude, and the light emitting element 25 is mounted on the pedestal portion 22b.

  The light emitting element 25 mounted on the pedestal portion 22b is a substantially cubic microchip, and has a pair of element electrode portions on the lower surface. The pair of element electrode portions are conductively connected to the base portion 22b via a solder member. The light emitting element 25 is composed of a gallium nitride compound semiconductor light emitting element or a quaternary light emitting element. Moreover, in order to improve the protection and light condensing property of the light emitting element 25, it is sealed in a hemispherical shape by the translucent resin material 33 on the base portion 22b.

  The reflective frame 31 is provided with a mortar-shaped recess 32. The recess 32 is provided to reflect upward the light emitted from the light emitting element 25 exposed at the bottom, and a metal film is formed on the inner peripheral surface of the recess 32 in order to increase the reflection efficiency. The The reflection frame 31 is fixed on the circuit body 22a via an insulating adhesive, and a translucent sealing resin material for protecting the light emitting element 25 is formed in the recess 32 in the reflection frame. It is applied so as to be flush with the upper surface of 31.

  FIG. 2 shows a mounting form when the light emitting diode 21 is used as a top emission type. In this mounting form, the back surface of the circuit body 22a is placed on the mother board 29, and the electrode extensions 22c and 22d are bent vertically along the outer peripheral surface of the reflection frame 31 and fixed with an adhesive. . Then, a solder member 30 is applied to the outer surfaces of the bent electrode extensions 22c and 22d to form a solder fillet 30a. According to this mounting form, since the solder fillet 30a can be widely formed along the width direction and the thickness direction of the reflection frame 31, the reliability of the conductive connection is ensured and the shape inspection of the solder member 30 is facilitated. .

  FIG. 3 shows a mounting form when the light-emitting diode 21 is used as a side-emitting type. In this mounting form, one side surface of the reflection frame 31 is placed on the mother board 29, and the electrode extensions 22c and 22d are bent toward the side surface of the reflection frame body 31 in the same manner as the mounting form shown in FIG. , Fixed through an adhesive. And the solder member 30 is apply | coated and joined centering | focusing on the lower end part of the outer surface of this bent electrode extension part 22c, 22d. This mounting form is often used as a side-emitting backlight source that emits light from the side of the light guide plate. However, in the conventional light-emitting diode structure, the area where the solder member can be applied is centered on the through hole. The side surface of the circuit body 22a was limited. In this respect, since the electrode extension portions 22c and 22d are provided like the light emitting diode 21 of the present embodiment, the solder fillet 30a can be widely formed. As a result, more reliable conduction can be achieved, and the light emitting diode 21 can be bonded to the mother board 29 in a stable state.

  In addition, since the pair of electrode extension portions 22c and 22d is formed of a flat plate having substantially the same size as the side surface of the reflection frame 31, as shown in FIGS. In any mounting form of the mold, it is possible to secure a sufficient coating area of the solder member 30. In addition, since the electrode extension portions 22c and 22d are bent to the vicinity of the side surface of the reflection frame 31 when mounting, the mounting space does not take extra space compared to the conventional case.

  Since the light emitting diode 21 is provided with through holes 26 at the four corners of the circuit body 22a, the conventional mounting can be performed using the through holes. At that time, the pair of electrode extension portions 22c and 22d may be bent toward the side surface of the reflection frame 31 so as not to get in the way.

  Next, a method for manufacturing the light-emitting diode 21 having the above configuration will be described with reference to FIGS. FIG. 4 shows a collective flexible substrate (collective FPC) 41 which is the base of the light emitting diode 21. In the collective FPC 41, a plurality of formation regions of the light emitting diodes 21 are set, and a cathode electrode 23 and an anode electrode 24, and a pair of external connection electrodes corresponding to the cathode electrode 23 and the anode electrode 24 according to each formation region. 27 and 28 and through-holes 26 are collectively formed by etching. The formation region is set by cutting lines (X1, Y1, Y2) with the circuit body 22a and the pair of electrode extensions 22c, 22d as a unit.

  Next, as shown in FIG. 5, a pedestal portion 22 b for mounting the light emitting element 25 is formed from the back side of the collective FPC 41 by pressing. This processing is performed using a mold after the assembly FPC 41 is heated and softened. Then, the light emitting elements 25 are mounted one by one on the pedestal portion 22b via solder members.

  Next, as shown in FIG. 6, the collective reflecting frame 42 in which a plurality of mortar-shaped concave portions 32 are provided on the upper surface of the collective FPC 41 according to the arrangement position of the light emitting elements 25 is joined with an insulating adhesive. . The collective reflection frame 42 is formed in a separate process from the collective FPC 41. For example, a set of temporarily arranged adhesive sheets (not shown) in which the recesses 32 are continuously formed in the X-axis direction are arranged in the Y-axis direction at regular intervals, and are temporarily fixed to the adhesive sheet. There is a method of aligning and fixing the lower surface of the reflecting frame 42 on the collective FPC 41. Further, a translucent sealing resin material is applied in each of the recesses 32.

  Finally, the collective FPC 41 and the collective reflecting frame body 42 are diced simultaneously along the X-axis cutting line (X1), and then the collective FPC 41 is diced along the Y-axis cutting lines (Y1, Y2). By this dicing process, the single light emitting diode 21 is divided and formed.

  As described above, in the surface-mounted light-emitting diode 21 of the present invention, the circuit board 22 serving as a base is extended to provide the electrode extension portions 22c and 22d, and the electrode extension portions 22c and 22d are soldered to the motherboard. Since the structure is a part, the application area of the solder member can be expanded. In particular, in the side emission type mounting form as shown in FIG. 3, it is possible to improve the reliability of conduction bonding by the solder member 30. Further, since the electrode extension portions 22c and 22d are folded when mounting, there is no need for extra mounting space.

  In addition, in the light emitting diode 21 of the present embodiment, the through holes 26 are provided at the four corners of the circuit main body portion 22a so that the conventional mounting connection form is possible. However, when the electrode extension portions 22c and 22 are used, It does not necessarily have to be formed. Furthermore, the electrode extension portions 22c and 22d do not have to be formed in the same size as the side surface size of the reflection frame body 31 and may be of a size that can sufficiently hold the application of the solder member. It is set appropriately according to the mounting form. Further, the circuit board provided with the electrode extension of the present invention is not limited to the flexible board as shown in the above embodiment, but can be applied to a thin and flexible board using other materials. .

1 is a perspective view of a surface-mounted light emitting diode according to the present invention. It is sectional drawing which shows the mounting form at the time of using the said surface mount type light emitting diode as a top emission type. It is a side view which shows the mounting form at the time of using the said surface mount type light emitting diode as a side surface light emission type. It is a perspective view of collective FPC used as the base of the said surface mount type light emitting diode. It is a figure which shows the process of mounting a light emitting element in the said collective FPC. It is a figure which shows the process of dividing the said collective FPC and taking out a single surface-mounted light emitting diode. It is sectional drawing of the conventional surface mount type light emitting diode.

Explanation of symbols

21 Light-emitting diode 22 Circuit board (flexible board)
22a Circuit body 22b Base 22c, 22d Electrode extension (external connection electrode)
DESCRIPTION OF SYMBOLS 23 Cathode electrode 24 Anode electrode 25 Light emitting element 26 Through hole 27 External connection electrode 28 External connection electrode 29 Mother board 30 Solder member 30a Solder fillet 31 Reflective frame 32 Concave part 33 Translucent resin material

Claims (3)

A thin circuit board on which wiring electrodes are formed on the front surface and external connection electrodes that are electrically connected to the wiring electrodes are formed on the back surface, a light-emitting element mounted at a substantially central portion on the upper surface of the circuit board, and surrounding the light-emitting element Thus, in the surface-mounted light emitting diode provided with a reflective frame disposed above the circuit board,
The surface-mount type light emitting diode, wherein an electrode extension portion having an electrode portion that extends to the outer peripheral surface of the reflection frame body and is electrically connected to the external connection electrode is integrally formed on the circuit board. The surface-mount light-emitting diode according to claim 1, wherein the electrode extension portion extends in a left-right direction from a lower surface of the reflection frame body, and a surface side is bent and fixed to an outer peripheral surface of the reflection frame body. The surface-mount light-emitting diode according to claim 1, wherein the circuit board is formed of a flexible board integrally with the electrode extension.

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