JP2011124515A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of raising light extraction efficiency while suppressing deterioration of a molding by reducing light absorption by the molding. <P>SOLUTION: The light-emitting device includes: a first lead; a light-emitting element adhering to the first lead; a second lead which faces one end of the first lead and has one end electrically connected to the light-emitting element; the molding made of a translucent resin which has a recess and in which a reflective filler is dispersedly arranged, wherein the light-emitting element and the one end of the second lead are exposed on the bottom surface of the recess and the other end of the first lead and the other end of the second lead protrudes in mutually opposite directions; and a sealing resin layer which is filled in the recess to cover the light-emitting element and has a higher refractive index than the molding, and is translucent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device.

  A surface mounted device (SMD) type light-emitting device can increase mass productivity when a molded body made of resin having a recess is used as a housing. In this case, when titanium oxide fine particles are mixed in the molded body, the light emitted from the light emitting element strikes the inner wall of the recess and is reflected upward. For this reason, the light extraction efficiency can be increased.

  In addition, when the sealing resin is filled in the concave portion of the molded body, the light emitting element bonded to the bottom surface of the concave portion can be protected, so that reliability can be improved.

  For example, when a thermoplastic resin is used as the resin material of the molded body used as the housing, the refractive index is approximately 1.6. Further, when silicone is used as the sealing resin, the refractive index is about 1.4. When the light emitted from the light emitting element is incident from a sealing resin having a low refractive index toward a molded body having a high refractive index, total reflection does not occur at the interface, so that the emitted light tends to gather on the molded body side and light extraction efficiency is improved. Decreases.

There is a disclosed example of a light emitting device that improves the extraction efficiency of light emitted from a light emitting element (Patent Document 1). In this example, a light-emitting element is formed using a resin sealing layer including a resin layer mainly composed of an epoxy resin or an acrylic resin and a zirconia-dispersed resin layer having a refractive index higher than that of the resin layer. It is sealed.
However, in this example, the resin sealing layer is often surrounded by a resin molded body having a high refractive index, and it is difficult to further increase the light extraction efficiency.

JP 2009-146924 A

  Provided is a light emitting device capable of reducing light absorption in a molded body and increasing light extraction efficiency while suppressing deterioration of the molded body.

  According to an aspect of the present invention, the first lead, the light emitting element bonded to the first lead, the one end of the first lead, and the light emitting element A molded body made of a translucent resin having a second lead having one end portion electrically connected and a concave portion and having a reflective filler dispersed therein, the bottom surface of the concave portion being at least The one end of the light emitting element and the second lead is exposed, and the other end of the first lead and the other end of the second lead are provided so as to protrude in opposite directions. And a sealing resin layer having a refractive index higher than the refractive index of the molded body and having a light-transmitting property, filled in the recess so as to cover the light emitting element. Is provided.

  Provided is a light-emitting device capable of reducing light absorption in a molded body and increasing light extraction efficiency while suppressing deterioration of the molded body.

1 is a schematic cross-sectional view of a light emitting device according to a first embodiment. Schematic sectional view of a light emitting device according to a comparative example Structural formula of silicone resin Schematic sectional view of a light emitting device according to a second embodiment Schematic sectional view of a light emitting device according to a third embodiment Schematic sectional view of a light emitting device according to a fourth embodiment Schematic cross-sectional view of a light emitting device according to a fifth embodiment

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A is a schematic plan view of the light emitting device according to the first embodiment of the present invention, FIG. 1B is a schematic cross-sectional view taken along the line AA, and FIG. 1C is a partially enlarged schematic cross-section. Figure.
The light emitting element 10 capable of emitting visible light or the like is bonded to one end side of the first lead 20 using a conductive adhesive or a metal solder material (not shown). An electrode (not shown) of the light emitting element 10 is electrically connected using one end portion of the second lead 22 facing one end portion of the first lead 20 and a bonding wire 36 made of a gold wire or the like. It is connected to the.

  The first and second leads 20 and 22 are made of copper or an iron-based alloy and have a thickness of 0.1 to 1 mm. Also, the reflectance can be increased by coating the surface of the lead with 100 nm thick Ni and 100 nm thick Ag by plating or the like.

  A molded body 30 having a cup-shaped concave portion that expands upward and made of resin is provided so as to embed one end of the first lead 20 and one end of the second lead 22. ing. The other end of the first lead 20 and the other end of the second lead 22 are provided so as to protrude from the molded body 30 in opposite directions. That is, the molded body 30 is a base material for the package of the light emitting device. The length L of the package can be 10 mm, the width W can be 5 mm, the height H can be 2 mm, and the like.

  On the bottom surface of the concave portion 30a of the molded body 30, the light emitting element 10 bonded to a part of the upper surface 20a of the first lead 20, the part of the upper surface 22a of one end of the second lead 22, and the bonding The wire 36 is exposed. The recessed part 30a of the molded body 30 has a cup part and a notch part 30b. Providing the notch 30b makes it easy to provide the bonding wire 36. Further, the lower surface 20 b of the first lead 20 and the lower surface 22 b of the second lead 22 are exposed from the lower surface of the molded body 30. If the lower surface 20b of the first lead 20, the lower surface 22b of the second lead 22, and the lower surface 30c of the molded body 30 are in the same plane, they can be securely attached to the circuit board.

  Furthermore, when the sealing resin layer 40 having translucency is filled so as to cover the light emitting element 10 in the recess 30a, the light emitting element 10 can be protected and the reliability can be improved.

  The molded body 30 can be molded using a thermosetting resin such as a silicone resin. The molded body 30 may be a white resin in which reflective fillers 32 made of potassium titanate fine particles and the like are dispersed. When the reflective fillers 32 are mixedly arranged in this way and the inclination is provided on the side wall of the recess 30a that forms the interface 31 with the sealing resin layer 40, the emitted light from the light emitting element 10 can be easily reflected upward. It becomes.

  The sealing resin layer 40 can be formed by filling a recess 30 a provided in the molded body 30 with a thermosetting resin such as a silicone resin and thermosetting the resin. In the schematic plan view of FIG. 1A, the region of the sealing resin layer 40 is shown by being filled.

FIG. 1C shows the operation of this embodiment. For example, the refractive index _{n m} of the molded body 30 and the like 1.4, and so 1.6 higher than the refractive index _{n m} of the molded body 30 a refractive index _{n s} of the sealing resin layer 40. Further, an incident angle of incident light from the sealing resin layer 40 filled around the light emitting element 10 to the molded body 30 is defined as θi1. In this case, the incident light is incident from a medium having a refractive index of 1.6 to a medium having a low refractive index of 1.4, so the critical angle θc is approximately 61 degrees. Light G1 having an incident angle θi1 equal to or greater than the critical angle θc is totally reflected at the interface 31 and does not enter the molded body 30.

On the other hand, light G2 with θc> θi1 ≧ 0 can enter the molded body 30. The incident light is reflected and scattered by the reflective filler 32 dispersedly arranged on the molded body 30. Of the scattered light, the incident angle of light from the molded body 30 to the sealing resin layer 40 is θi2. The light G3 of 90 °> θi2 ≧ 0 can return to the sealing resin layer 40 according to Snell's law expressed by the formula (1) without causing total reflection at the interface 31.

sin θt / sin θi = n ₁ / n ₂ formula (1)

Where θi: angle of incidence from medium 1 to medium 2 θt: angle of refraction in medium 2 n ₁ : refractive index of medium 1 n ₂ : refractive index of medium 2

  On the other hand, light that cannot be incident on the interface 31 after being reflected by the reflective filler 32 is difficult to take out effectively by being absorbed in the molded body 30. Note that in this specification, the refractive index is measured at the emission light wavelength of the light emitting element 10.

The light emitting element 10 is, for example, a light emitting diode. Specifically, the light emitting element _{10, In x (Ga y Al 1} -y) 1-x P (0 ≦ x ≦ 1,0 ≦ y ≦ 1) comprising represented by the composition formula InGaAlP based material and Ga _x It has a light emitting layer made of a GaAlAs material represented by a composition formula of Al _1-x As (0 <x ≦ 1) and emits light in the green to red wavelength range. Alternatively, the light-emitting element 10 is a light-emitting layer made of a nitride-based semiconductor represented by a composition formula of In _x Ga _y Al _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1). And emit light in the ultraviolet to green wavelength range.

  For example, when the light emitting element 10 emits blue light, if phosphor particles 42 made of a silicate material are dispersedly arranged in the sealing resin layer 40, the phosphor particles 42 that have absorbed blue light are converted into yellow light as wavelength converted light. Release. For this reason, white light and an incandescent light bulb color can be obtained as a mixed color of blue light and yellow light. Further, using phosphor particles 42 made of a YAG (Yttrium Aluminum Garnet) material, wavelength converted light such as red and green can be generated, and light of three colors or more can be mixed. The average particle diameter of the phosphor particles may be in the range of 1 to 50 μm. The path of the wavelength-converted light is determined by the refraction direction and the critical angle determined by the two refractive indexes of the interface.

FIG. 2A is a schematic plan view of a light emitting device according to a comparative example, and FIG. 2B is a schematic cross-sectional view taken along the line BB.
A light emitting element 110 capable of emitting visible light or the like is adhered to one end portion of the first lead 120 using an adhesive or the like. An electrode (not shown) of the light emitting element 110 is electrically connected to one end portion of the second lead 122 facing the one end portion of the first lead 120 and a bonding wire 136 such as a gold wire. It is connected. A molded body 130 having a recess 130 a having a cup portion and made of resin is provided so as to embed one end portion of the first lead 120 and one end portion of the second lead 122. The light emitting element 110, one end portion of the second lead 122, and the bonding wire 136 are exposed on the bottom surface of the recess 130a. In the molded body 130, fine particles of a reflective filler 132 such as potassium titanate are dispersedly arranged.

  In the comparative example, the molded body 130 is made of polyamide resin, polyphthalamide resin, or the like, and has a refractive index of, for example, 1.6. Further, the sealing resin layer 140 filled in the recess 130 is made of silicone resin, and its refractive index is 1.4. Light traveling from the sealing resin layer 140 around the light emitting element 110 toward the molded body 130 can enter the molded body 130 without causing total reflection at the interface 131. That is, Snell's law of Formula (1) is established between the incident angle θi11 and the refraction angle θt11.

On the other hand, when the light enters the sealing resin layer 140 from the molded body 130, the critical angle is approximately 61 degrees. For this reason, among the light reflected by the reflective filler 132, the light having the incident angle θi 22 in the range represented by the formula (2) can return to the sealing resin layer 140.

61 °> θi22 ≧ 0 Formula (2)

On the other hand, the light G1 having the incident angle θi22 in the range represented by the expression (3) is totally reflected by the interface 131 and absorbed in the molded body 130.

90 ° ≧ θi22 ≧ 61 ° Formula (3)

  That is, total reflection does not occur when incident from the sealing resin layer 140 to the molded body 130, and total reflection occurs when incident from the molded body 130 to the sealing resin layer 140. For this reason, the amount of light remaining in the molded body 130 increases, and it is difficult to increase the light extraction efficiency from above the sealing resin layer 140.

  On the other hand, in this embodiment, the light incident on the molded body 30 is reduced as compared with the comparative example, and further, the ratio of the light returning to the sealing resin layer 30 is lower than that in the comparative example because it is not totally reflected at the interface 31. Many. For this reason, the amount of light absorbed in the molded body 30 can be reduced, and the amount of light emitted from the sealing resin layer 40 to the outside can be increased. That is, light absorption is reduced and light extraction efficiency can be increased.

3A shows a structural formula of a dimethyl silicone resin, and FIG. 3B shows a structural formula of a phenyl silicone resin. For example, the resin used for the molded body 30 may be a dimethyl silicone resin having a refractive index of approximately 1.4 shown in FIG. Further, when one of the methyl groups CH ₃ is substituted with a phenyl group C ₆ H ₅ , a phenyl silicone resin can be obtained. The refractive index of the phenyl silicone resin can be, for example, between 1.4 and 1.6, and can be used as the sealing resin layer 40.

  The inventor examined the luminous intensity and its change with time in the first embodiment and the comparative example. As a light-emitting element, a chip in which a light-emitting layer made of a GaN / InGaN quantum well layer is provided on a SiC substrate is used. First and second leads made of a copper alloy and a reflective filler made of titanium oxide fine particles are dispersed. Light emitting devices each including a molded body that is disposed and made of a silicone-based material and a sealing resin layer in which yellow phosphor particles are dispersedly disposed were prepared.

  As a result, it was found that when the chromaticity was set to 0.3, the luminous intensity of the first embodiment was approximately 5% higher than that of the comparative example. In addition, the luminous intensity after 1000 hours of continuous operation decreased by approximately 12% from the initial value in the comparative example. On the other hand, the luminous intensity of the present embodiment was improved by about 3% lower than the initial value. In general, when the wavelength range of emitted light of the light emitting element 10 is shorter than that of blue light, the resin is likely to be discolored by irradiation of the emitted light. In this embodiment, it has been found that it is easy to suppress a change in reflectance or transmittance of light due to such resin discoloration, and it is possible to suppress a change in luminous intensity even after 1000 hours of operation.

FIG. 4A is a schematic plan view of the light emitting device according to the second embodiment, and FIG. 4B is a schematic cross-sectional view taken along the line AA. Similar to the first embodiment represented in FIG. 1, the refractive index _{n m} of the molded body 30 is 1.4, the refractive index _{n s} of the sealing resin layer 40 to 1.6. In the present embodiment, the first lead 21 has a cup-shaped recess 21a. The depth R of the recess 21a is 0.5 mm, the diameter D of the bottom surface 21c of the recess 21a is 2 mm, and so on. The size of the light emitting element 10 is a square with a side length of 0.5 mm, a thickness of 0.4 mm, and the like. The inclination of the side wall of the recess 21a of the first lead 21 can be set to an appropriate angle in accordance with the required directivity.

  When such a light emitting element 10 is bonded to the bottom surface 21c of the recess 21a, the light G5 emitted from the light emitting element 10 to the side is reflected by the side wall of the recess 21a and travels upward. In the present embodiment, it is possible to reduce the light incident on the side wall of the recess 30a of the molded body 30 at an incident angle smaller than the critical angle, and to reduce light absorption in the molded body 30. Further, when the depth R of the concave portion 21a of the first lead 21 is made larger than the thickness of the light emitting element 10, the light directed to the side can be reflected further upward.

FIG. 5A is a schematic plan view of the light emitting device according to the third embodiment, and FIG. 5B is a schematic cross-sectional view taken along the line AA.
On the top surface 40a of the sealing resin layer 40 filled in the concave portion 30a is made of a silicone-based resin, a refractive index lower than the refractive index n _s of the sealing resin layer 40, the outer space such as air An upper resin layer 28 higher than the refractive index is provided. The upper resin layer 28 does not have to be dispersed with a reflective filler or phosphor particles.

For example, if the refractive index between the sealing resin layer 40 having a refractive index n _s is 1.6 provided upper resin layer 28 having an intermediate refractive index of 1.4 between the first air layer, the sealing resin layer 40 The amount of light staying inside can be reduced, and the light extraction efficiency can be increased. In addition, when a spherical surface or minute unevenness is provided on the upper surface 28a of the upper resin layer 28, it becomes easy to reduce the total reflection on the upper surface 28a and further improve the light extraction efficiency.

FIG. 6A is a schematic plan view of the light emitting device according to the fourth embodiment, and FIG. 6B is a schematic cross-sectional view taken along the line AA. A lower resin layer 26 is provided so as to cover the light emitting element 10. The lower resin layer 26 is made of a silicone-based resin, and its refractive index is 1.6, which is lower than the refractive index of the light emitting element 10 and higher than that of the sealing resin layer 40. The refractive index _{n m} of the molded body 30 is 1.4, the refractive index of the sealing resin layer 40 filled in the concave portion 30a covers the lower resin layer 26 is 1.45, that. In this case, if the lower resin layer 26 is a spherical surface or a spherical surface that protrudes outward, such as an ellipsoidal shape, the upward light G6 is condensed and emitted from the light emitting element 10. Moreover, the light G7 which goes to the side is condensed, hits the side wall of the cup-shaped recess 21a, and is reflected upward. For this reason, high light extraction efficiency is possible.

  In addition, when the light emitting element 10 consists of nitride type semiconductors, the refractive index is between 2.5-2.7. Further, when the light emitting element 10 is made of an InGaAlP-based semiconductor, the refractive index is around 3.2.

  FIG. 7A is a schematic plan view of the light emitting device according to the fifth embodiment, and FIG. 7B is a schematic cross-sectional view taken along the line AA. If the first lead 21 and the second lead 23 protrude from the side surface of the molded body 30 but are not exposed from the bottom surface 30d of the molded body 30, the molded body 30 and the first and second leads 21 are exposed. , 23 can be easily improved.

  According to the first to fifth embodiments, it is possible to provide a light emitting device in which a molded body made of resin is suppressed from being deteriorated by emitted light or wavelength converted light, and light extraction efficiency is increased. Such a light-emitting device can be widely used for lighting devices, display devices, traffic lights, and the like.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments. Those skilled in the art have made design changes with respect to the material, size, shape, arrangement, etc. of the molded body, sealing resin layer, lead, reflective filler, phosphor particles, silicone resin, and light-emitting element constituting the present invention. However, it is included in the scope of the present invention without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Light emitting element, 20, 21 1st lead, 21a (lead) recessed part, 22, 23 2nd lead, 26 Lower resin layer, 28 Upper resin layer, 30 Molded body, 30a (molded body) Recessed part, 32 Reflectivity Filler, 42 phosphor particles

Claims (5)

The first lead,
A light emitting device bonded to the first lead;
A second lead having one end facing one end of the first lead and electrically connected to the light emitting element;
A molded body made of a translucent resin having a recess and a reflective filler dispersedly disposed, wherein the one end of the light emitting element and the second lead is exposed on the bottom surface of the recess, A molded body provided such that the other end of the first lead and the other end of the second lead protrude in opposite directions;
A sealing resin layer filled in the recess so as to cover the light emitting element, having a refractive index higher than the refractive index of the molded body, and having translucency;
A light-emitting device comprising:   The first lead has a bottom surface to which the light emitting element is bonded and a side wall capable of reflecting light emitted from the light emitting element upward, and is more than the recess provided in the molded body when viewed from above. The light emitting device according to claim 1, wherein the light emitting device has a small recess.   It further includes an upper resin layer that is provided on the sealing resin layer and has a refractive index that is higher than the refractive index of the external space and lower than the refractive index of the sealing resin layer, and has translucency. The light emitting device according to claim 1 or 2, characterized in that:   It is provided under the sealing resin layer so as to cover the light emitting element, has a refractive index lower than the refractive index of the light emitting element and higher than the refractive index of the sealing resin layer, and has translucency. The light emitting device according to claim 1, further comprising a lower resin layer.   The light-emitting device according to claim 1, wherein the concave portion of the molded body is expanded upward.

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