JP5724183B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device on which a light emitting element is mounted, and particularly to a light emitting device used for a display device such as an LED display.

  As a result of the development of light-emitting diodes (LEDs) capable of emitting RGB (red, green, blue) colors and LEDs capable of emitting white light with high brightness, LED displays configured by arranging a plurality of LEDs The device is being applied to various fields. For example, LEDs have an extremely long life compared to light bulbs, are highly efficient, and are resistant to vibration. Utilizing these characteristics, LEDs, advertisements, destination information and road information display, traffic light sources, small to large It has been used as a display.

  As such an LED, in order to suppress a decrease in display contrast, an LED in which a dark color paint such as black or amber or a resin layer is provided on the outer surface of a white resin is known (for example, Patent Documents 1 to 3). 3). As an example of such an LED, a package body having a recess made of a white resin, a semiconductor light emitting element mounted on the bottom surface of the recess, a sealing resin filled in the recess, and an upper surface of the package body are formed. And a dark resin layer. Thereby, when a plurality of LEDs are arranged in parallel, it is possible to suppress a decrease in display contrast due to an LED being turned off receiving external light or light of another LED being turned on.

  Further, in order to improve the light extraction efficiency, a light emitting device in which a light diffusing member having a relatively small particle size such as silica is contained in the sealing resin that covers the LED chip, or particulate light on the surface of the package. A light emitting device in which a layer containing a diffusion member is formed has been proposed (see, for example, Patent Document 4).

Japanese Patent Laid-Open No. 06-274378 JP 2000-183405 A JP 2006-108640 A JP 2003-86846 A

  In an LED display device using an LED or a plurality of LEDs at present, the reduction in display contrast is reduced regardless of whether it is outdoors or indoors, as the application field is expanded or higher display quality is required. On the other hand, further improvement is required.

  That is, when the LED is lit, external light such as sunlight or illumination hits at a certain angle, so that light is reflected mainly on the surface of the sealing resin in the LED, and the display contrast is reduced. There was a problem. In addition, even when the LED is not lit, external light hits the upper and side surfaces of the LED on the viewing side, causing reflection of light on the surface, so-called glare, and a whitish appearance. End up. Of course, also in the case of an LED display device in which a plurality of LEDs are arranged on a substrate, the display contrast is lowered for the same reason as described above.

  As a result, as shown in FIG. 4, the LED or LED display device, which originally maintained the display quality because the upper surface of the LED, which is the viewing side, is a dark color system, reflects light on the surface. As a result, not only the display contrast is lowered, but there is a problem that the quality of the LED or the LED display device is deteriorated due to glare or whitish reflection. Further, when the sealing resin crawls up on the dark color layer, light is reflected on the surface of the sealing resin, and the display contrast is lowered.

  FIG. 4 is a schematic cross-sectional view showing a conventional light emitting device. The conventional light emitting device shown in FIG. 4 includes a package main body 31 having a recess, a first lead terminal 32a and a second lead terminal 32b partially covered by the package main body 31, and a bottom surface of the recess. The semiconductor light emitting device 33 is mounted on the exposed lead terminal 32a, and the metal wire 34 electrically connects the semiconductor light emitting device 33 and the lead terminals 32a and 32b. Further, a dark color layer 36 is formed on the upper surface of the package body 31. The recesses of the package body 31 are filled with a sealing resin 35 that covers the semiconductor light emitting element 33 and contains particles that scatter the light emitted from the semiconductor light emitting element 33. Since the sealing resin 35 is filled after the dark color layer 36 is formed, a part of the sealing resin 35 crawls on the dark color layer 37, and the resin coating portion 37 covered with the sealing resin 35 is formed. May be formed. Although light reflection is suppressed in the portion where the dark color layer 36 is exposed, the light is reflected on the surface of the resin coating portion 37, so that the display contrast is lowered.

  In addition, the method of forming a layer containing a light diffusing member on the surface after filling with the sealing resin increases the manufacturing process, which increases the cost. In addition, it is necessary to expose the lead frame for soldering, and coating after solder mounting on the board to avoid soldering defects will result in defective products for each board if coating fails, so the yield will increase. Decrease significantly.

  In order to solve the above problems, a light emitting device includes a package body having a recess, a semiconductor light emitting element mounted on the bottom surface of the recess, and a translucent sealing resin filled in the recess. The sealing resin contains particles and is formed from the recesses to the upper surface of the package body, and at least on the upper surface of the package body, the surface has a protrusion along the shape of the particles, A dark color layer is formed on the upper surface of the package body via the sealing resin.

The following configurations can be combined with the above light-emitting device.
A part of the upper surface has an exposed portion exposed from the sealing resin, and the dark color layer covers at least a boundary between the exposed portion and the sealing resin.
The upper surface has a step composed of a lower step portion covered with the sealing resin and an upper step portion exposed from the sealing resin.
The sealing resin has a convex portion along the shape of the particle on the surface of the concave portion.
The particles are crushed.
The package body is made of a white resin, and the dark color layer is made of a black resin.

  According to the present invention, when external light is irradiated, so-called glare on the upper surface of the light emitting device can be reduced, so that the viewer does not feel uncomfortable and the reduction in display contrast can be greatly reduced. A light-emitting device that can be obtained can be easily obtained. Furthermore, the light from the inside of the light emitting element can be uniformly scattered and emitted to the outside, and the color mixing property of the light from the inside of the light emitting element can be improved.

FIG. 1 is a schematic cross-sectional view showing a light-emitting device according to Embodiment 1 of the present invention. It is typical sectional drawing to which a part of light-emitting device shown in FIG. 1 was expanded. FIG. 3 is a schematic cross-sectional view showing a light-emitting device according to Embodiment 2 of the present invention. FIG. 4 is a schematic cross-sectional view showing a conventional light emitting device.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a semiconductor device and a method for forming the semiconductor device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device and the method for forming the same to the following. Absent.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

[Embodiment 1]
FIG. 1 shows a schematic cross-sectional view of a light emitting device according to Embodiment 1 of the present invention. The light emitting device includes a package body 1 having a recess, a first lead terminal 2a and a second lead terminal 2b that are partially covered and exposed by the package body 1, and a first lead terminal that is exposed at the bottom of the recess. The semiconductor light emitting element 3 mounted on 2a and the sealing resin 4 filled in the recess so as to cover the semiconductor light emitting element 3 are included. The semiconductor light emitting element 3 and the lead terminals 2 a and 2 b are electrically connected by a metal wire 6. The sealing resin 4 contains particles, and the surface has convex portions along the particles. A part of the sealing resin 4 is also formed on the upper surface 1 a of the package body 1, and a dark-colored layer 5 is formed on the sealing resin 4.

  FIG. 2 shows a schematic diagram in which a part of the light emitting device shown in FIG. 1 is enlarged. As shown in FIG. 2, convex portions along the shape of the particles 7 are formed on the surface of the sealing resin 4 so as to cover the surface of the sealing resin 4 formed on the upper surface 1 a of the package body 1. A dark color layer 5 is formed. As a result, the creeping of the sealing resin 4 to the dark color layer 5 can be prevented, and light can be scattered by the convex portions on the surface of the dark color layer 5 formed by the convex portions on the surface of the sealing resin 4. And a reduction in display contrast can be suppressed. The convex portions on the surface of the dark color layer 5 become convex portions along the shape of the particles 7 contained in the sealing resin 4. The convex portion on the surface of the sealing resin 4 is preferably provided at least in a region where the dark color layer 5 is formed, and more preferably, the convex portion is also provided on the surface of the sealing resin 4 on the concave portion. Thus, by arranging the convex portions along the shape of the particles 7 on the entire surface of the sealing resin 4, reflection of external light can be suppressed and a reduction in contrast can be reduced.

(Package body)
As a specific material of the resin constituting the package, an insulating member is preferable. In addition, a member that does not easily transmit light from the semiconductor light emitting element or external light is preferable. Further, it has a certain degree of strength, and a thermosetting resin, a thermoplastic resin, or the like can be used. More specifically, a phenol resin, a glass epoxy resin, a BT resin, PPA, or the like can be given. The package body preferably has a recess in which the semiconductor light emitting element can be placed. The recess has a side surface and a bottom surface. A lead terminal is exposed on the bottom surface, and the semiconductor light emitting element is placed on the exposed lead terminal. Moreover, the reflectance of the light in the wall surface of a recessed part can be improved by comprising a package main body with white resin, and light extraction efficiency can be improved.

(Lead terminal)
The shape of the lead terminal is not particularly limited. A function that can be electrically connected to the semiconductor light-emitting element, and is partly embedded in the base and extended so as to protrude from the outside of the base, and the extended portion can be electrically connected to the outside. As long as it has. As a material for the lead terminal, it is preferable to use a material having a relatively large thermal conductivity. By forming with such a material, the heat generated in the semiconductor element can be efficiently released. For example, those having a thermal conductivity of about 200 W / (m · K) or more are preferable. Furthermore, a material having a relatively large mechanical strength or a material that can be easily punched or etched or etched is preferable. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron, nickel, iron-nickel alloys, phosphor bronze, iron-containing copper, and the like.

  The lead terminal has a first lead terminal and a second lead terminal. As shown in FIG. 1, the semiconductor light emitting element 3 is mounted on the first lead terminal 2a, and the semiconductor light emitting element 3 is connected to the first lead terminal 2a and the second lead terminal 2b by a metal wire 6.

(Semiconductor light emitting device)
A semiconductor light emitting device having an arbitrary wavelength can be selected. For example, as blue and green light emitting elements, those using ZnSe or a nitride semiconductor (In _X Al _Y Ga _1- XYN, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) are used. it can. As the red light emitting element, GaAs, InP, or the like can be used. Furthermore, a semiconductor light emitting element made of a material other than this can also be used. The composition, emission color, size, number, and the like of the light emitting element to be used can be appropriately selected according to the purpose. Further, a light-emitting element that outputs not only light in the visible light region but also ultraviolet rays and infrared rays can be obtained. Furthermore, a light receiving element or the like can be mounted together with the semiconductor light emitting element. Arbitrary light emission can be obtained by arranging a phosphor that converts the wavelength of light emitted from the semiconductor light emitting element around the semiconductor light emitting element. For example, a white light can be obtained by combining a blue light emitting semiconductor light emitting element and a yellow light emitting phosphor.

(Sealing resin)
The inside of the recess in which the semiconductor light emitting element is placed is sealed with a sealing resin. The sealing resin is a member that protects the semiconductor light emitting element and the metal wire placed on the package from dust, moisture, external force, and the like, and a light-transmitting member that can transmit light from the semiconductor light emitting element is used. It is done. Specific examples of the material include a silicone resin and an epoxy resin. The sealing member is preferably used in an amount that completely covers the semiconductor light emitting element.

(particle)
The shape of the particles can be spherical or crushed. Spherical particles are likely to settle, and it is difficult for convex portions corresponding to the shape of the particles to be formed on the surface of the sealing resin. For this reason, the light extraction efficiency from the sealing resin can be improved, but the flat sealing resin surface easily reflects extraneous light, and so-called glare occurs. In order to suppress glare, it is preferable to use crushed particles. By using crushed particles, the surface area can be made larger than spherical particles of the same size and the sedimentation of the particles can be suppressed, so that the resin can be cured in a state where the particles are present above the sealing resin. . The particles 7 shown in FIG. 2 are an example of crushed particles. By arranging the particles 7 in the vicinity of the surface of the sealing resin 4 in this way, the convex portions along the shape of the particles 7 can be distributed and arranged on the surface of the sealing resin 4, and reflection of external light can be performed. It is possible to suppress the reduction in contrast.

  The concentration of the particles is preferably greater than 20%, whereby the particles can be retained in the vicinity of the surface of the sealing resin, and convex portions along the shape of the particles can be formed. On the other hand, if the concentration of the particles is increased, it is difficult to extract light from the sealing resin, resulting in a decrease in luminous intensity and uneven light distribution. Therefore, the particle concentration is preferably 60% or less, more preferably 40% or less, and more preferably. Is 30% or less. The size of the particles can be, for example, about 0.5 to 10 μm.

  The particles are not particularly limited, but inorganic members such as silicon oxide (silica), titanium oxide, barium titanate, aluminum oxide, acrylic resin, urethane resin, melamine resin, CTU guanamine resin, benzoguanamine resin, etc. An organic member can be suitably used. A pigment or a fluorescent material powder may also be used. The particles are preferably a member that can be used as a light scattering agent, and the color unevenness of the light emitting device can be improved by dispersing such particles in the sealing resin to scatter light emitted from the semiconductor light emitting device. In order to achieve both suppression of a decrease in display contrast and light extraction efficiency, the particles are preferably a non-colored translucent member.

(Dark color layer)
The dark color layer can be formed, for example, by adding a dark color pigment to a fluororesin, an acrylic resin, a silicone resin, a urethane resin, or the like. As the dark pigment, for example, an inorganic pigment mainly composed of carbon black can be used. An inorganic pigment containing carbon black as a main component has excellent durability against light deterioration as compared with organic pigments such as dyes, so that color change due to deterioration can be minimized. When the package body is made of resin, it is preferable that the dark color layer is also made of resin from the viewpoint of adhesion, for example, black resin is used. As a means for forming a dark color layer, a known method such as screen printing can be used. The dark color layer covers at least the upper surface of the package body and the sealing resin. When the package body is made of a material that has a higher reflectance to external light than a dark color layer such as a white resin, the reflection of external light is reduced by completely covering the upper surface of the package body with the dark color layer. it can. In consideration of manufacturing accuracy, the dark color layer is preferably formed continuously from the top surface of the package body to the inside of the package body, that is, the surface of the sealing resin located on the recess of the package body. On the other hand, in order to improve the light extraction efficiency, as shown in FIG. 1 and FIG. 2, a dark color layer is formed in the region excluding the sealing resin surface on the concave portion that becomes the light emitting surface of the light emitting device. It is preferable to expose the surface of the sealing resin from the dark color layer.

  The dark-colored layer is formed of a material having a low reflectance with respect to extraneous light. In addition to this, a structure having convex portions along the particles contained in the sealing resin can be used to further reduce the extraneous light. Reflection can be reduced. By making the film thickness of the dark color layer smaller than the average size of the particles, it is possible to easily form convex portions along the particles in the dark color layer. Specifically, for example, the film thickness is 1 to 10 μm. The film thickness referred to here indicates the film thickness of a dark color layer in a region where no convex portion is formed. Furthermore, by forming the dark color layer so thin that the convex portions along the shape of the particles are formed, absorption of light from the semiconductor light emitting element can be reduced, and a decrease in light extraction efficiency can be suppressed.

  By forming the sealing resin up to the upper surface of the package body, as shown in FIG. 1, the peripheral edge of the sealing resin rises. When extraneous light is irradiated, the periphery of the raised portion looks particularly glaring. Therefore, the dark color layer is preferably formed in a region including at least the raised portion of the peripheral portion of the sealing resin. Thereby, the glare on the upper surface of the light emitting device can be effectively reduced.

  The dark color layer is preferably formed so as to cover the boundary between the sealing resin and the package body. Accordingly, moisture can be prevented from entering from the interface between the sealing resin and the package body, and a highly reliable light-emitting device with improved moisture resistance can be obtained. In order to further improve the moisture resistance, it is preferable to increase the thickness of the dark color layer. Specifically, it is preferable to make the film thickness of the dark color layer thicker than the average size of the particles, for example, a film thickness of 10 to 100 μm.

[Embodiment 2]
FIG. 3 shows a schematic cross-sectional view of the light-emitting device according to Embodiment 2 of the present invention. In the light emitting device of the second embodiment, the upper surface 21a of the package body 21 includes a step having a lower step portion 28 and an upper step portion 29, and the sealing resin 24 containing particles is formed from the concave portion to the lower step portion 28. Except for this, the light emitting device is the same as that of the first embodiment. The lower step portion 28 is covered with the sealing resin 24, the upper step portion 29 is exposed from the sealing resin 24, and a dark color layer 25 is formed from the lower step portion 28 to the upper step portion 29.

  By providing the lower step portion 28 and the upper step portion 29 and forming the sealing resin 24 in the lower step portion 28, creeping of the sealing resin 24 can be reduced, manufacturing can be facilitated, and the yield can be improved. Further, by covering the interface between the sealing resin and the package body with the dark color layer 25 and preventing the ingress of moisture, the humidity can be maintained even when the package body 21 and the sealing resin 24 are peeled off due to aging. An effect of suppressing entry into the light emitting device can also be expected.

  The light that has entered the lower stage portion 28 tends to be absorbed by the dark color layer 25 and the package body 21, and is difficult to be taken out of the sealing resin 24. For this reason, in order to suppress a decrease in light extraction efficiency, it is preferable that the thickness of the sealing resin 24 formed in the lower step portion 28 is in the same range as in the first embodiment.

  On the other hand, in consideration of manufacturing accuracy, the step between the lower step portion 28 and the upper step portion 29 and the depth of the lower step portion 28 are preferably set to about 0.1 to 0.5 mm. The film thickness of the sealing resin 24 in the lower step portion 28 is set to about 50 to 100% of the depth of the lower step portion 28 so that the dark color layer 25 can be easily formed and the adhesion with the dark color layer 25 is improved. It can be improved. In order to prevent the sealing resin 24 from creeping up, the thickness of the sealing resin 24 is preferably 90% or less of the depth of the lower step portion 28. When the film thickness of the sealing resin 24 in the lower step portion 28 is larger than the size of the particles, it is preferable that the shape of the particles is crushed, and thereby the convex portions along the shape of the particles on the surface of the sealing resin 24 Can be easily formed.

  The semiconductor device according to the present invention can be used for light emitting devices used for displaying advertisements, destination guidance, road information, etc., light sources for traffic lights, small to large displays, and the like.

1, 21 Package body, 1a, 21a Upper surface 2a, 22a of package body First lead terminal, 2b, 22b Second lead terminal 3, 23 Semiconductor light emitting element 4, 24 Sealing resin 5, 25 Dark color layers 6, 26 Metal wire 7 Particle 28 Lower stage part 29 Upper stage part 31 Package body 32a, 32b Lead terminal 33 Semiconductor light emitting element 34 Metal wire 35 Sealing resin 36 Dark color layer 37 Resin coating part

Claims (5)

A package body having a recess, a semiconductor light emitting element mounted on the bottom surface of the recess, and a translucent sealing resin filled in the recess,
The sealing resin contains particles and is formed from the concave portion to the upper surface of the package body, and at least on the upper surface of the package body, the surface has a convex portion along the shape of the particles,
A dark color layer is formed on the upper surface of the package body via the sealing resin,
The film thickness of the dark color layer is thicker than the average size of the particles,
The dark color layer is formed on the upper surface of the package body so as to cover a boundary between the sealing resin and the package body,
A light emitting device in which a sealing resin surface on the concave portion is exposed from the dark color layer. The light emitting device according to claim 1, wherein the upper surface has a step including a lower step portion covered with the sealing resin and an upper step portion exposed from the sealing resin. The sealing resin, the light emitting device according to claim 1 or 2 having convex portions along the shape of the particles to the surface on the recess. The light emitting device according to any one of claims 1 to 3, wherein said particles are crushed. The package body is made of white resin, the light emitting device according to any one of claims 1-4 wherein the dark color layer of consisting of black resin.

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