JP2005064419A - Light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting diode that firmly fixes a resinous package as well as improving brightness by efficiently condensing beams emitted laterally. <P>SOLUTION: In a light emitting diode 1 having a semiconductor light emitting device 3 mounted on a printed-wiring board 2 and a translucent resinous package 4 that covers the semiconductor light emitting device 3, the resinous package 4 has an expansion part 12 having a first curved surface 11 that slowly expands toward the surface, and the printed-wiring board 2 has a recessed part 5 having a second curved surface 7 that slowly expands toward the surface such that the beams emitted laterally from the semiconductor light emitting device 3 are reflected on the surface side. Moreover, the peel strength is improved by increasing the contact area between the resinous package 4 and the printed-wiring board 2, and further, the beams emitted laterally from the semiconductor light emitting device are reflected by the second curved surface as well as by the first curved surface, thus reflecting all the laterally emitted beams toward the surface side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting diode including a semiconductor light emitting element mounted on a printed wiring board and a translucent resin package covering the semiconductor light emitting element.

  2. Description of the Related Art Conventionally, domestic mobile phones with cameras are becoming mainstream, and for this reason, there is a demand for a compact, thin, high-intensity strobe light source that can take a picture even in a dark place. Light emitting diodes (LEDs) are the most powerful light sources that meet this requirement, but light emitting diodes that do not adjust the light distribution range often have insufficient luminance. A lens is formed with a resin package covering a light emitting element.

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

  In addition, the device 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 the light extraction surface of the resin package and a convex lens portion formed inside the concave portion. In this structure, light emitted in the front direction of the semiconductor light emitting element is extracted through a convex lens portion and condensed.

Further, what is described in Patent Document 3 has a structure in which a light emitting diode and a transparent portion made of a synthetic resin material are provided on the surface of a substrate, and the light emitted from the light emitting diode is totally reflected by the transparent portion.
JP-A-1-273367 (page 1-4, FIG. 3) JP-A-8-306959 (page 2-3, FIG. 2) Japanese Utility Model Publication No. 52-7580 (1-8 pages, Fig. 6)

  However, since the light-emitting diode described in Patent Document 1 is blocked by the light reflected by the concave mirror hitting the semiconductor light-emitting element and the lead member that supports the semiconductor light-emitting element, the light-emitting diode cannot perform uniform light emission and the light emission efficiency deteriorates. In particular, when the diameter is reduced, the ratio of the blocking area to the light emitting area is relatively increased, and thus there is a problem that it is not possible to cope with downsizing.

  Further, in the light emitting diode described in Patent Document 2, light emitted from the semiconductor light emitting device to the side is emitted to the outside as it is from the side surface of the resin package.

  Moreover, since the transparent part on a board | substrate is formed so that the light emission of the light emitting diode may be totally reflected in the light emitting diode described in patent document 3, the front part of the transparent part becomes larger than the base part, and the base part is There is a problem that it is easy to peel off from the substrate.

  Accordingly, an object of the present invention is to provide a light emitting diode in which light emitted to the side is condensed without waste to improve luminance and a resin package is firmly fixed.

  In the light emitting diode of the present invention, the resin package includes a widened portion having a first curved surface that is gradually widened toward the front side so that the light emitted from the semiconductor light emitting element sideways is totally reflected to the front side. Provided on the printed wiring board is a recess having a second curved surface that gradually expands toward the front side so that the light emitted from the semiconductor light emitting element to the side is reflected to the front side.

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

  As described above, according to the present invention, the resin package is provided with the enlarged portion having the first curved surface that totally reflects light, and the printed wiring board is provided with the concave portion having the second curved surface that reflects light. Therefore, the concave portion formed in the substrate can make the shape of the contact surface between the resin package and the substrate more complex than the flat surface, increase the contact area, improve the peel strength, and firmly fix the resin package. In addition, the light emitted from the semiconductor light emitting device to the side can be reflected by the second curved surface together with the first curved surface, and the light emitted from the side can be condensed without waste to improve the luminance. .

  Moreover, when the base end of the first curved surface is connected to the front side end of the second curved surface, the light reflected by the first curved surface and the second curved surface out of the light emitted to the front side of the resin package By reducing the boundary with the reflected light, the reduction in luminance can be reduced.

  In addition, when the semiconductor light emitting element is mounted on the printed wiring board via the submount element, the light emitting surface of the semiconductor light emitting element is moved to the front side, and the light incident on the first curved surface is increased from the semiconductor light emitting element. Can be improved.

  Further, when the first curved surface and the second curved surface are rotational paraboloids, the light incident on the first curved surface is totally reflected on the surface side, and the light incident on the second curved surface is directed on the surface side. The light can be reflected to prevent the light from being emitted to the outside of the concave portion, and all the light emitted from the semiconductor light emitting element can be emitted to the surface side to improve the luminance.

  In addition, when the second curved surface is formed by covering the same metal as the electrode, the electrode and the reflecting surface can be used together to improve the light reflectance and the manufacturing efficiency.

  The invention according to claim 1 is a light emitting diode comprising a semiconductor light emitting element mounted on a printed wiring board and a translucent resin package covering the semiconductor light emitting element, wherein the resin package is the semiconductor light emitting element. A widened portion having a first curved surface gradually widened toward the front side so as to totally reflect light emitted sideways from the front side, and the printed wiring board is laterally extended from the semiconductor light emitting element. A light emitting diode comprising a concave portion having a second curved surface that gradually expands toward the front side so as to reflect the light emitted to the front side. Makes the shape of the contact surface between the resin package and the substrate more complex than a flat surface, increases the contact area, improves the peel strength, and emits from the semiconductor light emitting element to the side The light in conjunction with the first curved surface is reflected by the second curved surface has the effect that reflects all the front light emitted laterally.

  The invention according to claim 2 is the light emitting diode according to claim 1, wherein a base end of the first curved surface is connected to a front side end of the second curved surface. In addition, of the light emitted to the front side of the resin package, the boundary between the light reflected by the first curved surface and the light reflected by the second curved surface is reduced.

  The invention according to claim 3 is the light emitting diode according to claim 1 or 2, wherein the semiconductor light emitting element is mounted on the printed wiring board via a submount element. The light emitting surface of the semiconductor light emitting element is moved to the front side to increase the amount of light incident on the first curved surface from the semiconductor light emitting element.

  The invention according to claim 4 is the light emitting diode according to any one of claims 1 to 3, wherein the first curved surface and the second curved surface are rotational paraboloids. The light incident on the first curved surface from the semiconductor light emitting element is totally reflected to the surface side, and the light incident on the second curved surface is prevented from escaping outside the recess, and the semiconductor light emitting element is emitted. It has the effect of emitting all light to the surface side.

  The invention according to claim 5 is characterized in that the second curved surface is formed by coating a metal of the same material as that of the electrode. The light emitting diode according to any one of claims 1 to 4 It has the effect of improving the light reflectance and manufacturing efficiency by combining the electrode and the reflective surface.

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

(First embodiment)
FIG. 1A is a plan view of the light emitting diode according to the first embodiment, and FIG. 1B is a side sectional view of the light emitting diode.

  As shown in FIG. 1, the light emitting diode 1 includes a semiconductor light emitting element 3 mounted on a printed wiring board 2 and a translucent resin package 4 that covers the semiconductor light emitting element 3.

  The printed wiring board 2 is formed in a rectangular shape, and electrode patterns 8 and 9 are formed on both ends.

  A non-penetrating recess 5 is formed on the surface of the printed wiring board 2. The recess 5 has a circular bottom surface 6 and a curved surface 7 that is a rotating paraboloid formed around the bottom surface 6. The center line of the paraboloid of revolution passes through the center of the bottom surface 6 and is arranged in parallel to the normal direction of the printed wiring board 2. An insulating white paint (reflective paint) containing a reflective material such as titanium oxide is applied to the bottom surface 6 and the curved surface 7 of the recess 5.

  The electrode patterns 8 and 9 of the printed wiring board 2 extend from both ends of the printed wiring board 2 into the recess 5 and are opposed to both sides in the longitudinal direction of the printed wiring board 2. The electrode patterns 8 and 9 are obtained by performing an Ni / Au plating process on an etching pattern of Cu, and both wire bonding property and reflow soldering property at the time of surface mounting are achieved.

  The semiconductor light emitting element 3 is connected to the electrode pattern 8 of the printed wiring board 2 via the submount element 10 by die bonding. Specifically, the semiconductor light emitting element 3 is disposed at the center of the bottom surface 6, and the wire bonding region of the submount element 10 is disposed on one side of the semiconductor light emitting element 3.

  The electrode pattern 9 is disposed on the opposite side of the wire bonding region of the submount element 10 with the semiconductor light emitting element 3 interposed therebetween, and the wire passes through the front side of the semiconductor light emitting element 3 and is connected to the electrode pattern 9 and the submount. The element 10 is connected.

  The front side refers to the direction in which the concave portion 5 of the printed wiring board 2 is provided.

  Since the wire is thin, it does not disturb all the light emitted from the semiconductor light emitting element 3, and most of the light can be emitted from the semiconductor light emitting element 3. 1A, the electrode pattern 9 is formed to extend to a position adjacent to the wire bonding region of the submount element on the bottom surface 6 as indicated by a two-dot chain line and a hatched line, and the wire is formed on the extended portion. When connected, the light emitted from the semiconductor light emitting element 3 is not obstructed, and the light emitted from the semiconductor light emitting element 3 to the front side can be increased.

  Since the semiconductor light emitting element 3 is disposed in the recess 5 of the printed wiring board 2, it is possible to prevent light emitted from the semiconductor light emitting element 3 from leaking to the back side of the printed wiring board 2.

  The resin package 4 is made of, for example, a resin such as transparent epoxy, and a base portion that covers and solidifies the entire semiconductor light emitting element 3 and part of the electrode patterns 8 and 9 in the recess 5 of the printed wiring board 2, and the printed wiring board 2. An enlarged portion 12 having a curved surface 11 which is disposed so as to protrude from the surface to the front side and gradually expands toward the front side so as to totally reflect light emitted from the semiconductor light emitting element 3 to the front side. I have.

  The curved surface 11 forms a first curved surface that is a paraboloid of revolution, and the curved surface 7 formed in the concave portion 5 of the printed wiring board 2 forms a second curved surface. The base end of the curved surface 11 is connected to the front end of the curved surface 7.

  An annular flat surface portion 13 orthogonal to the optical axis of the semiconductor light emitting element 3 is formed on the outer peripheral portion of the surface of the resin package 4, and an adjustment concave portion 14 for adjusting a light distribution range is formed inside the annular flat surface portion 13. Further, a convex lens portion 15 having the same optical axis as the optical axis of the semiconductor light emitting element 3 is formed in the adjustment concave portion 14.

  A circular flat surface portion 16 is formed at the tip of the convex lens portion 15, and the circular flat surface portion 16 is disposed on the same plane as the annular flat surface portion 13. That is, the convex lens portion 15 is provided in a state where it does not protrude from the adjustment concave portion 14. Further, the circular flat portion 16 is formed in a size that includes the entire circumference of the rectangular semiconductor light emitting element 3 when viewed from the front. The adjustment concave portion 14 has an outer peripheral edge of the convex lens portion 15 and a concave curved surface portion 17 connecting the inner peripheral edge of the annular flat surface portion 13.

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

  First, the surface of the printed wiring board 2 is cut with a bit matched to the shape of the curved surface 7, and then electrode patterns 8 and 9 are formed by plating, etching, or the like. Then, an insulating white paint is applied to the bottom surface 6 and the curved surface 7 of the recess 5.

  Next, the semiconductor light emitting element 3 is mounted on the electrode patterns 8 and 9, but this procedure is the same as the conventional light emitting diode manufacturing procedure, and thus the description thereof is omitted.

  For the production of the resin package 4, a transfer mold is used. In this case, a pair of molds that can move to the front side and the back side of the printed wiring board 2 and a mold that slides to both sides to form the curved surface 11 are used. By using a slide mold, it is possible to manufacture even in a shape in which the curved surface 11 protrudes on the back surface side.

  Next, the usage state of the light emitting diode 1 will be described.

  The light emitting diode 1 can be used as a surface mount type device. A part of the light emitted from the semiconductor light emitting element 3 in the optical axis direction is emitted to the outside from the circular flat portion 16 and goes straight. Further, the light hitting the peripheral surface of the convex lens portion 15 is refracted to the front side in the optical axis direction and is emitted from the convex lens portion 15 to the outside. The convex lens portion 15 and the concave curved surface portion 17 are formed so that the light emitted outward from the convex lens portion 15 does not enter the concave curved surface portion 17 again.

  Light emitted laterally from the semiconductor light emitting element 3 hits the curved surface 7 or the curved surface 11, but the curved surface 7 and the curved surface 11 are paraboloids, and the curved surface 7 and the curved surface 11 of the light emitted from the semiconductor light emitting element 3. The incident angle is designed to be almost 40 ° or more.

  The reason for this design is that the total reflection angle is 40 ° when the refractive index of the package resin is 1.55. If the resin material is changed, the total reflection angle is designed according to the total reflection angle. The angle can be changed. Thereby, almost all the light incident on the curved surface is totally reflected by the curved surface 7 and the curved surface 11 and is emitted to the front side in the optical axis direction.

  When light is applied to another member and reflected, the light diffusely reflected at the interface is absorbed by the other member and the reflection efficiency is deteriorated. Therefore, it is more efficient that the light is totally reflected and reflected by the surface of the resin. On the other hand, when the incident angle of light with respect to the surface of the resin is reduced, the light is transmitted to the outside, and the reflection efficiency is extremely lowered.

  In the present embodiment, since two types of curved surfaces 7 and 11 are provided, the light incident on the curved surface 11 from the semiconductor light emitting element 3 is incident at a larger incident angle than the light incident on the curved surface 7, so that Reflected. Further, light emitted obliquely backward from the semiconductor light emitting element 3 and incident on the curved surface 7 has a small incident angle of less than 40 °. However, since the curved surface 7 is formed on the printed wiring board 2, the light is curved. It does not go out from 7 and is reflected efficiently. Further, light emitted more backward from the semiconductor light emitting element 3 is reflected to the front side by the bottom surface 6 and the surfaces of the electrode patterns 8 and 9.

  In the present embodiment, since the semiconductor light emitting element 3 is mounted on the bottom surface 6 of the recess 5 via the submount element 10, the light emitting surface of the semiconductor light emitting element 3 moves to the front side and enters the curved surface 11. And the light can be reflected more efficiently.

  Further, since the base portion of the resin package 4 is formed by being fitted into the recess 5, the peel strength can be increased as compared with the case where the resin package is formed in a planar shape on the substrate.

(Second Embodiment)
FIG. 2A is a plan view before forming the resin package of the light emitting diode of the second embodiment, and FIG. 2B is a side sectional view before forming the resin package of the light emitting diode.

  The light-emitting diode 18 according to the second embodiment is different from the light-emitting diode according to the first embodiment only in the configuration of the electrode pattern and the arrangement of the wires, and the configuration of the other parts is the same.

  In the light emitting diode 18, a reflective surface 23 is formed by covering a curved surface (second curved surface) formed in the concave portion 20 of the printed wiring board 19 with a metal of the same material as the electrode patterns 21 and 22.

  The electrode pattern 21 covers one end of the printed wiring board 19, covers a substantially half circumference of the curved surface in the recess 20, and further covers a substantially half of the bottom surface 24 in the recess 20. The electrode pattern 22 covers the other end of the printed wiring board 19, covers a substantially half circumference of the curved surface in the recess 20, and covers a substantially half of the bottom surface 24 in the recess 20. The electrode patterns 21 and 22 in the recess 20 are formed with a slight gap that does not cause a short circuit.

  The semiconductor light emitting element 3 is mounted on the submount element 10, and the submount element 10 is connected to the electrode pattern 21 by die bonding and connected to the electrode pattern 22 by wire bonding. The wires are connected to positions adjacent to the wire bonding region of the submount element 10 and are arranged so as not to interfere with the light emitted from the semiconductor light emitting element 3 to the front side.

  The light emitting diode of the present invention has a concave portion formed on the substrate, which makes the shape of the contact surface between the resin package and the substrate more complex than a flat surface, increases the contact area, improves the peel strength, and firmly fixes the resin package. In addition, the light emitted laterally from the semiconductor light emitting element is reflected by the second curved surface together with the first curved surface, thereby concentrating the light emitted laterally without waste and improving the luminance. It is useful as a light emitting diode comprising a semiconductor light emitting element mounted on a lead frame and a translucent resin package covering the semiconductor light emitting element.

(A) is a top view of the light emitting diode of 1st Embodiment, (B) is a sectional side view of the light emitting diode. (A) is a plan view before forming the resin package of the light emitting diode of the second embodiment, (B) is a side sectional view before forming the resin package of the light emitting diode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode 2 Printed wiring board 3 Semiconductor light emitting element 4 Resin package 5 Recessed part 6 Bottom surface 7 Curved surface 8 Electrode pattern 9 Electrode pattern 10 Submount element 11 Curved surface 12 Enlarged part 13 Annular plane part 14 Adjustment recessed part 15 Convex lens part 16 Circular shape Planar portion 17 Concave curved surface portion 18 Light emitting diode 19 Printed wiring board 20 Recessed portion 21 Electrode pattern 22 Electrode pattern 23 Reflecting surface 24 Bottom surface

Claims (5)

In a light emitting diode comprising a semiconductor light emitting element mounted on a printed wiring board, and a translucent resin package covering the semiconductor light emitting element,
The resin package includes a widened portion having a first curved surface gradually widened toward the front side so as to totally reflect light emitted from the semiconductor light emitting element sideways to the front side,
The printed wiring board includes a recess having a second curved surface that gradually expands toward the front side so as to reflect light emitted from the semiconductor light emitting element to the side to the front side. Light emitting diode. 2. The light emitting diode according to claim 1, wherein a base end of the first curved surface is connected to a front side end portion of the second curved surface. The light emitting diode according to claim 1 or 2, wherein the semiconductor light emitting element is mounted on the printed wiring board via a submount element. The light emitting diode according to any one of claims 1 to 3, wherein the first curved surface and the second curved surface are paraboloids. 5. The light-emitting diode according to claim 1, wherein the second curved surface is formed by coating a metal made of the same material as that of the electrode.

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