JP2009032850A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device that makes it possible to accurately mix a desired amount of an additive into a resin material. <P>SOLUTION: The light-emitting device includes a case 2, an element mounting part 22 formed on the bottom face of the case 2 and having a prescribed height, and an LED chip 3 mounted to the element mounting part 22. The case has a reflective part 23 formed with an opening 2a and having a curved reflecting face 21 while being made of a resin material including TiO<SB>2</SB>, coated with a heat-resistant stabilizer or a light-resistant stabilizer, as a filler 200. Light emitted from the LED chip 3 to a part close to the bottom face in a direction of the reflecting face 21 is reflected to the side of the opening 2a by the reflecting face 21 of the case 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device having a case for housing a light emitting element.

  2. Description of the Related Art Conventionally, a surface mount type light emitting device is known in which an LED chip is disposed on the bottom surface of a case having an opening on one surface, and a light transmissive resin is filled in the case. The inner surface of the case serves as a reflection surface for light emitted from the LED chip. The reflection surface is formed so as to expand at a predetermined angle with respect to the bottom surface from the bottom surface side to the opening side of the case. Thereby, the light emitted from the LED chip to the side is reflected to the opening side on the inner surface and taken out from the opening of the case.

  As this type of light emitting device, a material in which a case is formed using a polyamide-based resin (nylon) as a material excellent in moldability is known (for example, see Patent Document 1). In recent years, electronic devices such as the above-described light emitting devices have been miniaturized, and mounting by solder reflow is performed. Therefore, it is required to secure heat resistance and case strength to withstand solder reflow. In the light emitting device described in Patent Document 1, a heat-resistant agent and a reinforcing material are added to the polyamide-based resin material.

Moreover, as this kind of light-emitting device, there is one including a light-reflective filler in a case made of a polyamide-based resin material (for example, see Patent Document 2). The light emitting device described in Patent Document 2 contains a filler such as titanium oxide or potassium titanate that imparts light reflectivity to the polyamide-based resin constituting the case.
JP-A-2-288274 JP 2002-374007 A

  However, according to the light emitting device described in Patent Document 2, since heat is generated in the mixing step of mixing the filler with the polyamide-based resin material, the additive mixed with the filler together with the filler is volatilized by the heat and is required for the case. There is a problem that desired characteristics cannot be obtained. In particular, such a tendency is remarkable in the heat resistance stabilizer and the light resistance stabilizer.

  Accordingly, an object of the present invention is to provide a light emitting device capable of accurately mixing a desired amount of an additive into a resin material.

  In order to achieve the above object, in the present invention, a light emitting device, a case formed of a resin material and including a filler coated on the surface with an additive added to the resin material, and the case are provided integrally. Exposed on the bottom surface of the opening formed on one surface of the case, the lead on which the light emitting element is mounted and electrically connected to the light emitting element, and the light emitting element and the lead housed in the opening are sealed. There is provided a light emitting device including a sealing resin for stopping.

  According to this light-emitting device, since the additive to be added to the resin material constituting the case is coated on the surface of the filler, the heat is generated by mixing during the formation of the resin material that forms the base of the case. , Volatilization of the additive can be suppressed. Moreover, by suppressing the volatilization of the additive, a desired addition amount to be added to the resin material can be accurately added.

  In the light emitting device, the resin material is preferably made of a polyamide resin mixed with the filler.

  In the light emitting device, the filler is preferably titanium oxide.

  In the above light emitting device, the filler preferably has a particle size of 0.01 to 3 μm.

  In the light emitting device, the filler is preferably at least one of calcium silicate and potassium titanate.

  In the light emitting device, the filler has a particle diameter of 0.1 to 5 μm and a length of 1 to 20 μm with respect to the calcium silicate and the potassium titanate, and a fiber length and diameter with respect to the glass fiber. The ratio is preferably 10 to 50.

  In the light emitting device, the additive is preferably at least one of a heat resistance stabilizer composed of a hindered phenol compound and a light resistance stabilizer composed of a hindered amine compound.

  In the above light emitting device, it is preferable that the case has an element mounting portion protruding in the light extraction direction on the bottom surface of the opening.

  ADVANTAGE OF THE INVENTION According to this invention, a desired quantity of additive can be accurately mixed in the resin material which comprises the case of a light-emitting device.

  1 to 4 show an embodiment of the present invention. FIG. 1 is a schematic external perspective view of a light emitting device, and FIG. 2 is a schematic front view of the light emitting device.

  As shown in FIG. 1, the light emitting device 1 includes a reflective case 2 having a reflective portion 23 in which an opening 2 a is formed and a reflective surface 21 is curved. As shown in FIG. 2, the light emitting device 1 includes an element mounting portion 22 having a predetermined height formed on the bottom surface of the reflection case 2 made of a resin material containing the filler according to the present embodiment, and the element mounting portion 22. LED chip 3 as a light-emitting element mounted on the. The LED chip 3 is surrounded by the reflection portion 23 of the reflection case 2. A negative electrode lead 4 and a positive electrode lead 5 connected to the electrodes of the LED chip 3 are disposed on the bottom surface of the reflection case 2. As shown in FIG. 1, the negative electrode lead 4 and the positive electrode lead 5 are formed to the outside of the reflection case 2 and are connected to the wiring portion of the substrate when mounted on the substrate.

  The light emitting device 1 is used in a planar light emitting device used for a liquid crystal backlight, a panel meter, an indicator lamp, a surface emitting switch, and the like. The planar light emitting device includes a light guide plate on which light from the light emitting device 1 is incident on an end surface, and emits light in a planar shape from the light emitting surface of the light guide plate. That is, the light emitting device 1 is relatively thin corresponding to the thickness of the light guide plate. When the substrate is mounted, the opening 2a is directed laterally (in a direction substantially parallel to the substrate), and light is extracted from the opening 2a substantially parallel to the substrate. The opening 2a has a substantially rectangular shape that is long in the horizontal direction when viewed from the front. In the present embodiment, the upper center side of the opening 2a is formed to expand upward.

FIG. 3 is a schematic cross-sectional view of the light emitting device. The reflective case 2 is made of, for example, a polyamide-based resin, and glass fiber as a reinforcing agent and titanium oxide (TiO ₂ ) for enhancing light reflectivity are mixed as a filler 200 in an aromatic polyamide-based resin. TiO ₂ is a polyamide-based resin having a surface coated with a heat stabilizer or a light stabilizer. In addition, in this polyamide-type resin, additives other than glass fiber and titanium oxide can be mixed in the range which does not inhibit the characteristic as a case. The glass fiber has a needle-like or rod-like shape, a diameter of 5 to 10 μm, a length of 150 to 175 μm, and a ratio of the length to the diameter (length / diameter) of 10 to 50 is used. In order to obtain strength, it is preferable that 10 to 25% by weight is mixed with the polyamide resin material. Examples of other additives include fillers, oxidation stabilizers, mold release agents, antistatic agents, and plasticizers.

  As shown in FIG. 3, the reflection surface 21 of the reflection case 2 is formed so as to expand from the bottom surface side of the reflection case 2 toward the opening 2 a side. The reflecting surface 21 includes, in order from the opening 2a side, an inclined section 21a having a constant inclination angle with respect to the bottom surface, a curved section 21b that curves so as to narrow toward the bottom surface side, and an offset section that extends perpendicularly to the bottom surface side. 21c. That is, the reflecting surface 21 is formed in a stepped shape in the offset section 21c, the bottom section is formed in a curved shape, and the opening section is formed in a straight line.

  On the bottom surface of the reflection case 2, an element mounting portion 22 protruding to a predetermined height is formed. In the present embodiment, the height of the element mounting portion 22 is 100 to 150 μm. Moreover, the height from the bottom face of the offset section 21c of the reflective surface 21 is also 100 to 150 μm. The height from the bottom surface of the element mounting part 22 and the offset section 21c is the same, or the element mounting part 22 is configured to be higher. In addition, it is more preferable that the element mounting portion 22 is formed higher than the offset section 21c from the bottom surface, rather than the same height.

  A negative electrode lead 4 and a positive electrode lead 5 are disposed on the bottom surface of the reflection case 2. The negative electrode lead 4 and the positive electrode lead 5 are made of, for example, a copper alloy plated with silver. Here, the offset section 21 c of the reflecting surface 21 extends vertically from the upper surface of each lead 4, 5. One end of each lead 4, 5 is embedded in the side surface of the element mounting portion 22 and insulated by the element mounting portion 22. In the present embodiment, the distance between the leads 4 and 5 in the element mounting portion 22 is 100 to 200 μm.

  As shown in FIG. 3, the element mounting portion 22 is formed integrally with the reflective case 2, and the LED chip 3 is mounted with the die bond paste 7. When the thickness of the die bond paste 7 is 5 to 10 μm and the heights from the bottom surfaces of the element mounting portion 22 and the offset section 21 c are the same, the lower end position of the LED chip 3 is the amount of the die bond paste 7 and the reflection surface 21. It becomes higher than the height of the offset section 21c. The element mounting portion 22 is formed so as to protrude from the bottom surface in the internal space inside the reflection case 2. The element mounting portion 22, the positive electrode lead 4, and the negative electrode lead 5 are exposed on the bottom surface of the reflection case 2 (see FIG. 2).

  Here, the curved section 21b that narrows toward the bottom surface side is suitable for reflecting light traveling obliquely downward upward. In the present embodiment, the light emitting layer as the light emitting portion of the LED chip 3 is disposed at a position higher than the curved surface 21 b of the reflecting surface 21 from the bottom surface. Thereby, the light emitted obliquely downward from the light emitting layer of the LED chip 3 is accurately reflected upward by the reflecting surface 21.

4A and 4B are enlarged views showing a partial cross section of the filler used in this embodiment. FIG. 4A shows the surface of TiO ₂ 210 as a filler 200 coated with a heat-resistant stabilizer 211 as an additive. TiO ₂ 210 has a rutile type and an anatase type, but in this embodiment, a rutile type having a small catalytic action is used. As this rutile TiO ₂ 210, one having a particle diameter of 0.01 to 3 μm can be used. FIG. 4B shows the case where the surface of TiO ₂ 210 as the filler 200 is coated with the light-resistant stabilizer 212 as an additive, and the other is the same as that when the heat-resistant stabilizer 211 is coated. By coating the additive on TiO ₂ 210 in this manner, the additive is mixed with the polyamide-based resin material while being supported on the filler 200. As a result, the volatilization loss of the additive due to heat is smaller than when the additive is added alone and mixed, and the additive is uniformly dispersed in the polyamide resin material together with the filler 200.

The heat stabilizer 211 is coated by diluting a heat stabilizer made of a hindered phenol compound in a solvent and spraying it on the surface of TiO ₂ 210.

  The light-resistant stabilizer 212 is coated by diluting a light-resistant stabilizer that is a hindered amine compound in a solvent and spraying it on the surface of TiO2210.

  The LED chip 3 is a face-up type blue LED chip having a light emitting layer that emits light having a wavelength of 460 nm. Each electrode of the LED chip 3 and each lead 4, 5 are connected by a wire 6. The LED chip 3 is sealed with a resin material 8 filled in the reflection case 2.

  The resin material 8 is a transparent resin containing a yellow phosphor. As the yellow phosphor, for example, a YAG (Yttrium Aluminum Garnet) -based or BOS (Barium ortho-Silicate) -based phosphor is used. When the yellow phosphor is excited by receiving blue light emitted from the LED chip 3, it emits yellow wavelength-converted light. As a result, light is extracted from the opening 2a in a white state in which blue light and yellow light are mixed.

  FIG. 5 is an explanatory diagram illustrating a path of light in the light emitting device. In FIG. 5, the hatching of the resin material is omitted for explanation. In the light emitting device 1 of the present embodiment, since the reflection surface 21 of the reflection case 2 is curved, the light incident on the reflection surface 21 can be accurately collected in the direction of the opening 2a. Further, since the curved section 21b is formed on the bottom surface side of the reflecting surface 21, the light emitted from the LED chip 3 toward the case bottom surface in the direction of the reflecting surface 21 can be accurately reflected toward the opening 2a.

  Further, since the curved section 21b is formed following the offset section 21c, the thickness of the bottom surface side end portion of the reflective surface 21 is not extremely reduced, and the curved shape of the reflective surface 21 can be easily formed. Specifically, when molding the reflective case 2 made of resin, it is not difficult for the resin to flow into the curved shape portion of the mold, and the curved section 21b can be formed in the desired shape. Thereby, the condensing performance by the curved area 21b can be exhibited reliably.

  Further, as shown in FIG. 5, since the element mounting portion 22 protrudes from the bottom surface of the reflection case 2, the light emitted from the LED chip 3 toward the bottom surface in the direction of the reflection surface 21 is reflected in the curved section 21 of the reflection surface 21. It can reflect to the opening 2a side. At this time, the light reflected by the curved section 21 advances to the opening 2a side and does not advance to the LED chip 3 side.

  Further, the light emitted from the LED chip 3 toward the leads 4 and 5 can be reflected by the leads 4 and 5. Here, since the LED chip 3 and the leads 4 and 5 are separated from each other, the light emitted from the LED chip 3 in the direction of the leads 4 and 5 travels a predetermined distance and then reaches the bottom surface of the reflection case 2. Reflected by the arranged leads 4 and 5. As a result, the light reflected by the leads 4 and 5 does not directly enter the LED chip 3 as in the conventional case where the LED chip 3 and the leads 4 and 5 are adjacent to each other. The light reflected by the leads 4 and 5 enters the opening 2a directly or indirectly via the reflecting surface 21.

  Moreover, since each lead | read | reed 4 and 5 is embedded in the element mounting part 22, each lead | read | reed 4 and 5 can be fixed reliably. In addition, the light emitted from the LED chip 3 to the element mounting portion 22 side is reflected using the embedded portion of each lead 4, 5, and the heat generated in the LED chip 3 is released through each lead 4, 5. be able to. The LED chip 3 may be mounted on either the lead 4 or 5 without being provided with the element mounting portion 22 and sealed with resin. In this case, the size of the element mounting portion 22 may be increased. Unlimited design freedom.

As described above, according to the light emitting device 1 of the present embodiment, the surface of the TiO ₂ 210 as the filler 200 is coated with the heat stabilizer 211 and the light stabilizer 212 added to the polyamide resin material constituting the reflective case 2. Therefore, the heat-resistant stabilizer 211 and the light-resistant stabilizer 212 can be prevented from volatilizing due to the heat generated when mixing the resin material that forms the base of the reflective case 2. A desired amount of additive can be accurately mixed with the resin material. In the present embodiment, the configuration in which the heat-resistant stabilizer 211 and the light-resistant stabilizer 212 are coated on TiO ₂ 210 as the filler 200 has been described, but the filler 200 may be, for example, calcium silicate or potassium titanate. Good. Further, by coating and mixing the glass fiber, it is possible to increase the case strength of the reflection case 2 and to mix a preferable amount of additive corresponding to the glass fiber having a large surface area.

Regarding the coating of the additive on the filler, for example, the reinforcing filler has an anisotropic shape so that the resin chain can be easily entangled, and is often biased depending on the flow path at the time of package molding. For this reason, the dispersion | distribution arises also in the dispersion | distribution about the additive to be coated. Therefore, it is preferable to apply the additive to the reflective case 2 to the reflective filler (TiO ₂ ) that hardly causes the above-described bias.

In addition, TiO ₂ 210 has a photocatalytic function, so that it does not decompose the resin material constituting the reflective case 2 to reduce the case strength, and a heat-resistant stabilizer and light-resistant stability that suppress the photocatalytic function. More preferably, the agent is selected.

  In addition, since the light incident on the reflecting surface 21 can be accurately condensed in the direction of the opening 2a, desired condensing characteristics can be obtained. Moreover, since the light radiate | emitted diagonally downward from the LED chip 3 can be reflected in the opening 2a side with the reflective surface 21 of the reflective case 2, light extraction efficiency can be improved.

  In addition, since the reflecting case 2 is made of resin, the curved section 21b can be easily formed as compared with ceramics, and the number of manufacturing steps does not increase because there is no need to laminate frames like ceramics.

  In the above-described embodiment, the LED chip 3 is mounted face-up on the element mounting unit 22. For example, as shown in FIG. 6, the LED chip 103 is flip-chip mounted on the element mounting unit 22. It may be a thing. Here, FIG. 6 is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 6 shows a light emitting device 101 in which a Zener diode 9 is used as a submount, and the electrodes of the Zener diode 9 and the leads 4 and 5 are connected by wires 6. According to this configuration, light emitted from the LED chip 103 can be reflected on the surface of the Zener diode 9, and heat generated in the LED chip 103 can be released through the Zener diode 9.

  Further, in the above-described embodiment, the opening 2a is directed in a direction substantially parallel to the substrate when the substrate is mounted, and light is extracted from the opening 2a substantially in parallel with the substrate. For example, FIGS. As described above, the opening 2a may be oriented in a direction perpendicular to the substrate when the substrate is mounted, and light may be extracted from the opening 2a substantially perpendicular to the substrate.

7 and 8 show a modification of the light emitting device. FIG. 7 is a schematic external perspective view of the light emitting device, and FIG. 8 is a schematic longitudinal sectional view of the light emitting device.
As shown in FIG. 7, the light-emitting device 201 is mounted on the substrate with the opening 202a of the reflection case 202 facing upward. The reflection case 202 has a substantially rectangular shape when viewed from above, and the positive electrode lead 4 and the negative electrode lead 5 extend to the lower surface of the reflection case 202 as shown in FIG. The reflective case 202 is made of a polyamide resin material containing TiO ₂ coated with a heat stabilizer and a light stabilizer.

9 and 10 show a modification of the light emitting device, FIG. 9 is a schematic external perspective view of the light emitting device, and FIG. 10 is a schematic longitudinal sectional view of the light emitting device.
As shown in FIG. 9, the light emitting device 301 is mounted on a substrate in a state where the opening 302a of the reflection case 302 is directed upward. The reflection case 302 has a substantially square shape when viewed from above, and the positive electrode lead 4 and the negative electrode lead 5 extend to the lower surface of the reflection case 302 as shown in FIG. The reflective case 302 is made of a polyamide resin material containing TiO ₂ coated with a heat stabilizer and a light stabilizer.

  In the above embodiment, the element mounting portion 22 is formed integrally with the reflection case 2. However, the element mounting portion 22 may be a separate member from the reflection case 2. In this case, the element mounting portion 22 is preferably a ceramic such as alumina or aluminum nitride.

  Moreover, in the said embodiment, although each lead | read | reed 4 and 5 showed what was embedded in the element mounting part 22, it does not necessarily need to be embedded. For example, when ceramic is used as the element mounting portion 22, a sufficient heat dissipation effect can be obtained without embedding the leads 4 and 5.

  In the above-described embodiment, the blue light LED chip 3 is used as the light emitting element. However, for example, an LED chip such as red light, green light, or ultraviolet light may be used as the light emitting element. For example, an LED chip of ultraviolet light may be used and red, green, and blue phosphors may be included in the resin material 8 to emit light in white.

  Moreover, in the said embodiment, although what curved the one part area of the reflective surface 21 was shown, it is needless to say that all the areas may be curved. Further, the length of the offset section 21c is arbitrary on the bottom surface side of the reflecting surface 21, and the offset section 21c may not be formed. In addition, it is needless to say that specific detailed structures can be changed as appropriate.

1 is a schematic external perspective view of a light emitting device according to an embodiment of the present invention. It is a model front view of a light-emitting device. It is a schematic cross-sectional view of a light-emitting device. It is an enlarged view which shows the partial cross section of the filler used by this embodiment. It is explanatory drawing which shows the path of light. It is a model cross-sectional view of the light-emitting device which shows a modification. It is a general | schematic external appearance perspective view of the light-emitting device which shows a modification. It is a model longitudinal cross-sectional view of the light-emitting device which shows a modification. It is a general | schematic external appearance perspective view of the light-emitting device which shows a modification. It is a model longitudinal cross-sectional view of the light-emitting device which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-emitting device 2 Reflection case 2a Opening 3 LED chip 4 Positive electrode lead 5 Negative electrode lead 6 Wire 7 Die bond paste 8 Resin material 9 Zener diode 21 Reflecting surface 21a Inclined section 21b Curved section 21c Offset section 22 Element mounting part 23 Reflecting part 101 Light emitting apparatus 103 LED chip 200 Filler 201 Light emitting device 202 Reflective case 202a Opening 210 Titanium oxide (TiO ₂ )
211 Heat Stabilizer 212 Light Stabilizer 301 Light Emitting Device 302 Reflective Case 302a Opening

Claims (8)

A light emitting element;
A case including a filler formed on a surface and coated with an additive formed by a resin material and added to the resin material;
A lead provided integrally with the case and exposed at a bottom surface of an opening formed on one surface of the case, the lead mounted with the light emitting element and electrically connected to the light emitting element;
A light emitting device comprising: the light emitting element accommodated in the opening; and a sealing resin for sealing the lead.   The light emitting device according to claim 1, wherein the resin material is made of a polyamide-based resin mixed with the filler.   The light emitting device according to claim 1, wherein the filler is titanium oxide.   The light emitting device according to claim 1, wherein the filler has a particle diameter of 0.01 to 3 μm.   The light-emitting device according to claim 1, wherein the filler is at least one of calcium silicate, potassium titanate, and glass fiber.   The filler has a particle diameter of 0.1 to 5 μm and a length of 1 to 20 μm with respect to the calcium silicate and the potassium titanate, and a fiber length to diameter ratio of 10 to 50 with respect to the glass fiber. The light emitting device according to claim 5.   The light-emitting device according to claim 1, wherein the additive is at least one of a heat-resistant stabilizer made of a hindered phenol-based compound and a light-resistant stabilizer made of a hindered amine-based compound.   The light emitting device according to claim 1, wherein the case has an element mounting portion protruding in a light extraction direction on the bottom surface of the opening.

Images