JP2004158830A - Light emitting diode - Google Patents

Abstract

Provided is a light emitting diode for improving the luminance by condensing light emitted to the side without waste.
A light emitting diode (1) includes a semiconductor light emitting element (4) mounted on lead frames (2) and (3), and a light transmitting resin package (5) covering one end of the lead frames (2) and (3) together with the semiconductor light emitting element (4). In the above, a curved surface is formed so as to protrude from the front surface of the resin package 5 on the back surface side, and both lead frames 2 and 3 are formed by bending in a Gull-Wing shape. In this case, the light-emitting diode 1 that collects the light emitted to the side without waste and improves the luminance can be obtained.
[Selection diagram] Fig. 1

Description

  The present invention relates to a light emitting diode including a semiconductor light emitting device mounted on a lead frame, and a translucent resin package covering the semiconductor light emitting device.

  2. Description of the Related Art Conventionally, mobile phones with a camera have become mainstream in Japan, and therefore, a small, thin, and high-brightness strobe light source capable of taking a picture even in a dark place has been demanded. As a light source that satisfies this requirement, a light-emitting diode (LED) is the most prominent. However, in a normal state, the luminance is often insufficient, and in order to solve the insufficient luminance, a resin package that covers the semiconductor light-emitting element is used. , Forming lenses.

  For example, in the device described in Patent Document 1, a semiconductor light-emitting element mounted on a lead member is covered with a resin package, and a surface formed in a convex shape of the resin package is plated to form a concave mirror. In this structure, the light is reflected by the light source, and the light is extracted and collected on the back side.

Further, the one described in Patent Document 2 covers a semiconductor light emitting element mounted on a lead member with a resin package, and forms a concave portion on a light extraction surface of the resin package and a convex lens portion formed inside the concave portion, This is a structure in which light emitted in the front direction of the semiconductor light emitting element is extracted through a convex lens portion and collected.
Japanese Patent Application Laid-Open No. 1-27367 (pages 1-4, FIG. 3) JP-A-8-306959 (page 2-3, FIG. 2)

  However, in the light emitting diode described in Patent Literature 1, light reflected by the concave mirror hits the semiconductor light emitting element and the lead member supporting the semiconductor light emitting element and is blocked, so that uniform light emission cannot be performed and light emission efficiency deteriorates. In particular, when the diameter is reduced, the ratio of the blocking area to the light emitting area becomes relatively large, so that there is a problem that it is impossible to cope with downsizing. Further, when a metal reflecting surface is formed by plating or metal deposition, there is a problem that the bonding between the resin package and the metal film is peeled off by reflow heating or thermal shock test during surface mounting.

  Further, in the light emitting diode described in Patent Document 2, light emitted to the side from the semiconductor light emitting element is directly emitted to the outside from the side surface of the resin package, so that there is much waste and the efficiency of luminance improvement is poor.

  Therefore, an object of the present invention is to provide a light emitting diode that collects light emitted to the side without waste and improves the luminance.

  In the light emitting diode of the present invention, the light emitting diode is formed by projecting a curved surface on the back surface side of the front surface with respect to the front surface of the resin package.

  According to the present invention, it is possible to obtain a light emitting diode in which light emitted to the side is condensed without waste and luminance is improved.

  As described above, according to the present invention, in a light emitting diode including a semiconductor light emitting element mounted on a lead frame and a resin package covering the semiconductor light emitting element, a curved surface protruding to the back side is formed on the back side of the resin package. The two lead frames are formed to be bent in a Gull-Wing shape, and in the arrangement state of the two lead frames, the other end portions are arranged on both sides, so that the semiconductor light emitting element emits the light laterally. In addition, the light hitting the curved surface can be reflected in the front side, that is, in the main light extraction direction of the semiconductor light emitting element, and the light emitted to the side can be condensed without waste and the luminance can be improved.

  Further, by using a printed circuit board as the lead frame, light emitted from the semiconductor light emitting element to the back side can be reflected to the front side, and light can be prevented from leaking to the back side.

  Further, when the semiconductor light emitting device is mounted in the concave portion formed on the printed circuit board, the light emitted from the back surface side and obliquely backward of the semiconductor light emitting device is all reflected to improve the brightness of the surface in the optical axis direction. Can be.

  The invention according to claim 1 is a light-emitting diode including a semiconductor light-emitting element mounted on a lead frame, and a light-transmitting resin package covering one end of the lead frame together with the semiconductor light-emitting element. On the back side of the front surface, a curved surface is formed so as to protrude from the front surface of the resin package, and both the lead frames are formed by being bent in a Gull-Wing shape, and the other end portions are arranged on both sides. The light emitting diode has a function of reflecting light emitted from the semiconductor light emitting element to the side and hitting the curved surface in the front side, that is, in the main light extraction direction of the semiconductor light emitting element. Have. In this specification, a lead frame includes a printed circuit board having an electrode pattern formed on an insulating substrate, in addition to a metal frame.

  The invention according to claim 2 is a light-emitting diode including a semiconductor light-emitting element mounted on a lead frame and a light-transmitting resin package that covers the semiconductor light-emitting element, with reference to the surface of the resin package. A curved surface is formed to protrude on the back surface side of the front surface, the lead frame is a printed circuit board, and the semiconductor light emitting element is mounted in a recess formed in the printed circuit board. It is a diode, and reflects the light emitted from the semiconductor light emitting element to the back side to the front side, and reflects the light emitted obliquely backward from the curved surface part of the outer periphery of the resin package at the side and bottom surfaces of the recess. This has the effect of further improving the light extraction efficiency on the surface side of the resin package.

  In addition, since the resin package is held on the bottom and side surfaces of the concave portion, the contact area between the resin package and the printed board increases.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.

(First Embodiment)
1A is a plan view of a light emitting diode according to a first embodiment of the present invention, FIG. 1B is a side view of the light emitting diode, FIG. 1C is a front view of the light emitting diode, and FIG. FIG. 4 shows a bottom view of the diode. As shown in FIG. 1, the light emitting diode 1 includes a semiconductor light emitting element 4 mounted on lead frames 2 and 3 and a translucent resin package 5 covering the semiconductor light emitting element 4.

  The lead frames 2 and 3 are each formed by bending into a Gull-Wing shape in which a Cu alloy or the like is subjected to Ni / Ag plating or the like. Are arranged on both sides so as to form a straight line. The rectangular parallelepiped semiconductor light emitting element 4 has a lower surface electrode connected to one lead frame 2 by die bonding, and an upper surface electrode connected to the other lead frame 3 by wire bonding.

  The resin package 5 is made of a resin such as transparent epoxy, for example, and is solidified together with the semiconductor light emitting element 4 so as to cover one end of the lead frames 2 and 3. The outer shape of the resin package 5 is formed in a substantially inverted cannonball shape. Here, in this specification, the front side of the lead frame 2 to which the semiconductor light emitting element 4 is connected, and the main light extraction direction of the semiconductor light emitting element 4 is expressed as the front side or front side, and the reverse direction is expressed as the back side or back side. And

  On the back side of the resin package 5, a curved surface 6 protruding to the back side with respect to the front side is formed. The curved surface 6 is formed of a paraboloid of revolution. The center line of the paraboloid of revolution is arranged perpendicular to the surface of the lead frame 2, and the focus of the paraboloid of revolution is the light of the semiconductor light emitting element 4. It is formed in line with the axis. The protruding portions projecting from the curved surface 6 of the resin package 5 to the rear surface side and covering the lead frames 2 and 3 are formed in a columnar portion at the rear side of the semiconductor light emitting element 4, and the lead frames 2 on both sides thereof are formed. , 3 are formed in a rectangular parallelepiped shape so as to reinforce one end of the lead frames 2, 3.

  An annular flat portion 9 orthogonal to the semiconductor light emitting device 4 is formed on the outer peripheral portion of the surface portion of the resin package 5, a concave portion 7 is formed inside the annular flat portion 9, and the semiconductor light emitting device 4 is further formed in the concave portion 7. The convex lens portion 8 having the same optical axis as the optical axis of the first lens is formed.

  A circular flat portion 11 is formed at the tip of the convex lens portion 8, and the circular flat portion 11 is arranged on the same plane as the annular flat portion 9. That is, the convex lens portion 8 is provided so as not to protrude from the concave portion 7. The circular flat portion 11 is formed to have a size that includes the entire periphery of the rectangular semiconductor light emitting element 4 when viewed from the front. The concave portion 7 has a concave curved surface portion 10 connecting the outer peripheral edge of the convex lens portion 8 and the inner peripheral edge of the annular flat portion 9.

  FIG. 2 is an explanatory diagram illustrating an optical path of light emitted from the semiconductor light emitting element. The shape of the concave curved surface portion 10 is set so as not to hinder the light emitted from the convex lens portion 8. That is, the light emitted from the convex lens portion 8 is designed not to enter the concave curved surface portion 10.

  Thus, the light emitting diode 1 is configured to be usable as a surface mount type.

  Next, a method for manufacturing the light emitting diode 1 will be described.

  The procedure for mounting the semiconductor light-emitting element 4 on the lead frames 2 and 3 is the same as the conventional procedure for manufacturing a light-emitting diode, and a description thereof will be omitted.

  In manufacturing the resin package 5, a transfer mold is used. In this case, a pair of dies that can be moved to the front side and the back side of the lead frames 2 and 3 and a mold that slides to both sides to form the curved surface 6 are used. By using a slide mold, manufacturing can be performed even in a shape in which the curved surface 6 protrudes to the rear surface side.

  Next, a usage state of the light emitting diode 1 will be described with reference to FIG.

  Part of the light emitted from the semiconductor light emitting element 4 in the optical axis direction is emitted outward from the circular flat portion 11 and proceeds straight. Further, the light hitting the peripheral surface of the convex lens portion 8 is refracted to the front side in the optical axis direction, and is emitted outward from the convex lens portion 8. The convex lens portion 8 and the concave curved surface portion 10 are formed such that light emitted from the convex lens portion 8 to the outside does not enter the concave curved surface portion 10.

  The light emitted laterally from the semiconductor light emitting element 4 hits the curved surface 6. The curved surface 6 is a paraboloid of revolution, and the angle of incidence of the light emitted from the semiconductor light emitting element 4 on the curved surface 6 becomes 40 ° or more. It is designed to be. As a result, almost all of the light incident on the curved surface 6 is totally reflected by the curved surface 6 and emitted to the front side in the optical axis direction.

  The reason why the semiconductor light emitting element 4 is arranged at the above position is that the total reflection angle becomes 40 ° when the refractive index of the package resin is 1.55, and when the material of the resin is changed, The position of the semiconductor light emitting element can be changed according to the total reflection angle.

  Light emitted from the light emitting layer of the semiconductor light emitting element 4 to the back side is reflected by the surface of the lead frame 2 and emitted to the front side.

  Thus, most of the light emitted from the semiconductor light emitting element 4 can be extracted in parallel to the front side in the optical axis direction. A part of the light emitted from the light emitting layer of the semiconductor light emitting element 4 in the oblique direction on the back side enters the part of the resin package 5 holding the lead frames 2 and 3, but is obliquely rearward from the semiconductor light emitting element. Since the amount of emitted light is originally small, it has little effect on the entire amount of light.

(Second embodiment)
3A is a plan view of a light emitting diode according to a second embodiment of the present invention, FIG. 3B is a side view of the light emitting diode, FIG. 3C is a front view of the light emitting diode, and FIG. FIG. 4 shows a bottom view of the diode.

  The light emitting diode 12 of the second embodiment is different from the light emitting diode 1 of the first embodiment in that the number of semiconductor light emitting elements is two and the number of lead frames is four.

  Each of the lead frames 13 to 16 is formed in a Gull-Wing shape, and is arranged in a cross shape with one end thereof being close to each other. The two semiconductor light emitting elements 17 and 18 are respectively connected to the opposing lead frames 13 and 15. Die bonded. The semiconductor light emitting device 17 is connected to the lead frame 14 by wire bonding, and the semiconductor light emitting device 18 is connected to the lead frame 16 by wire bonding. As shown in FIG. 3A, the centers of the semiconductor light emitting elements 17 and 18 are arranged at a predetermined distance.

  The resin package 25 is formed in an elliptical shape or a bale shape in plan view. The curved surface 26 on the back side of the resin package 25 is rotated around the optical axis of each of the semiconductor light emitting elements 17 and 18 except for a range a between the center lines of the semiconductor light emitting elements 17 and 18 shown in FIG. It is formed in a shape obtained by dividing the object surface into two parts, and is formed so that the normal section becomes rectangular between the areas a.

  The convex lens portions 19 and 20 are formed so that the optical axes thereof are aligned with the optical axes of the semiconductor light emitting elements 17 and 18. Since the semiconductor light emitting elements 17 and 18 are arranged close to each other, one of the peripheral surfaces to be superimposed. The parts are integrated. Further, the concave portions 21 and 22 and the concave curved surface portions 23 and 24 formed around the convex lens portions 19 and 20 are also overlapped, and each is formed in an annular shape connecting two arcs.

  The light emitted laterally from the light emitting layers of the semiconductor light emitting elements 17 and 18 is reflected by the curved surface 26 and emitted substantially in the optical axis direction. The light emitted to the front side is emitted through the convex lens portions 19 and 20 in a substantially optical axis direction.

  When a current flows through the lead frames 13 and 14 of the light emitting diode 12, the semiconductor light emitting element 17 emits light, and when a current flows through the lead frames 15 and 16, the semiconductor light emitting element 18 emits light. It is also possible to make both semiconductor light emitting elements 17 and 18 emit light at the same time. The semiconductor light-emitting elements 17 and 18 may emit light of two different colors. In this case, the semiconductor light-emitting elements 17 and 18 can generate each color or a mixed color of the two colors.

(Third embodiment)
In the light emitting diode of the third embodiment, three semiconductor light emitting elements are mounted on a lead frame, and each semiconductor light emitting element emits red, green, and blue light. Each semiconductor light emitting element can generate each color of red, green, and blue, a mixed color of two colors, or a mixed color of three colors, and can adjust the luminance of three colors to generate white light. Is also possible.

  White light using a yellow phosphor for blue light has a small amount of red component, so when used in a flash for photography, it emits white light different from natural light, but if it is a mixed color of three colors, it emits white light. Near white light emission can be obtained.

  By mounting three or more white semiconductor light-emitting elements (such as a blue LED coated with a phosphor), a high-power light-emitting diode can be formed. Light can be emitted.

(Fourth embodiment)
FIG. 4A is a plan view of a light emitting diode according to a fourth embodiment, and FIG. 4B is a cross-sectional view of the light emitting diode taken along the line AA.

  The light emitting diode 27 of the fourth embodiment uses a printed circuit board 28 as a lead frame instead of the lead frames 2 and 3 of the light emitting diode 1 of the first embodiment.

  The semiconductor light emitting element 4 is connected to the electrode pattern 29 of the printed board 28 by die bonding, and is electrically connected to the electrode pattern 30 separately formed on the printed board 28 by wire bonding. By using the printed board 28, it is possible to prevent light from leaking to the back surface side of the printed board 28. The electrode patterns 29 and 30 are subjected to Ni / Au plating on the Cu etching pattern to achieve both wire bonding and reflow soldering during surface mounting.

  FIG. 5A is a plan view of a light-emitting diode according to another embodiment, and FIG. 5B is a cross-sectional view of the light-emitting diode taken along the line BB. As shown in FIG. 5, a light emitting diode according to another embodiment has a non-penetrating recess 31 formed on the surface of a printed circuit board 28 of the light emitting diode 27 according to the fourth embodiment. Reflection surfaces formed by plating are formed on the bottom surface and the side surface 32 of the concave portion 31. The semiconductor light emitting element 4 mounted in the recess 31 is electrically connected to another electrode pattern 33 by wire bonding. Light emitted obliquely rearward from the semiconductor light emitting element 4 is totally reflected by the bottom surface and the side surface 32 of the concave portion 31 and is emitted to the surface in the optical axis direction by the resin package 34, so that higher brightness can be achieved.

  The light emitting diode of the present invention can improve the brightness by condensing the light emitted to the side without waste, and a semiconductor light emitting element mounted on a lead frame and a light transmitting resin covering the semiconductor light emitting element. It is useful as a light emitting diode having a package.

(A) is a plan view of the light-emitting diode according to the first embodiment of the present invention, (B) is a side view of the light-emitting diode, (C) is a front view of the light-emitting diode, and (D) is a light-emitting diode of the same. Bottom view Explanatory diagram showing an optical path of light emitted from a semiconductor light emitting element (A) is a plan view of a light emitting diode according to a second embodiment of the present invention, (B) is a side view of the light emitting diode, (C) is a front view of the light emitting diode, and (D) is a light emitting diode of the same. Bottom view (A) is a plan view of the light emitting diode of the fourth embodiment, and (B) is a side sectional view of the light emitting diode. (A) is a plan view of a light emitting diode according to another embodiment, and (B) is a side sectional view of the light emitting diode.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 light emitting diode 2, 3 lead frame 4 semiconductor light emitting element 5 resin package 6 curved surface 7 concave portion 8 convex lens portion 9 annular flat surface portion 10 concave curved surface portion 11 circular flat surface portion 12 light emitting diodes 13 to 16 lead frame 17, 18 semiconductor light emitting device 19 , 20 convex lens portion 21, 22 concave portion 23, 24 concave curved surface portion 25 resin package 26 curved surface 27 light emitting diode 28 printed circuit board 29, 30 electrode pattern 31 concave portion 32 side surface 33 electrode pattern 34 resin package

Claims (2)

In a light emitting diode comprising a semiconductor light emitting element mounted on a lead frame and a light transmitting resin package covering one end of the lead frame together with the semiconductor light emitting element,
With respect to the front surface of the resin package, a curved surface protrudes on the back surface side of the front surface,
A light-emitting diode, wherein both the lead frames are formed by bending into a Gull-Wing shape, and the other end portions are disposed on both sides. In a light emitting diode including a semiconductor light emitting element mounted on a lead frame and a light-transmitting resin package covering the semiconductor light emitting element,
With respect to the front surface of the resin package, a curved surface protrudes on the back surface side of the front surface,
The light emitting diode, wherein the lead frame is a printed circuit board, and the semiconductor light emitting element is mounted in a recess formed in the printed circuit board.

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