JP2013098427A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that in a conventional stacked LED device having a plurality of LED dies stacked therein, the type and the number of the LED dies to be stacked are limited, and an increase in luminance and an adjustable range of color tones are limited.SOLUTION: In an LED device 10 having a plurality of LED dies 1a to 1d stacked on a circuit board 3 having a wiring electrode, phosphor layers 2a to 2c and dichroic mirrors 6 and 7 are interposed between the LED dies 1a to 1d, and thereby reduction in the size and improvement in the luminance are achieved and stability of color tones and a change with time is achieved.

Description

  The present invention relates to a semiconductor light emitting device used for a backlight of a display device or a lighting device, and more particularly to a semiconductor light emitting device in which a plurality of semiconductor light emitting elements are stacked and packaged.

  In recent years, semiconductor light-emitting elements have long life and excellent driving characteristics, are small in size, have high light emission efficiency, and have bright emission colors, so that they are widely used in backlights of display devices, lighting devices, and the like. It has become. Hereinafter, unless otherwise specified, a semiconductor light emitting device cut out from a wafer is referred to as an LED die, and a semiconductor light emitting device in which the LED die is mounted on a circuit board, covered with a resin, and packaged is referred to as an LED device.

  Some LED devices have a plurality of LED dies mounted on a single circuit board. For example, a red light emitting LED die (R-LED die), a green light emitting LED die (G-LED die), and a blue light emitting LED die (B-LED die) have been developed. The device has been put into practical use. This additive color mixing type LED device can be used for a white illumination device by causing an R-LED die, a G-LED die, and a B-LED die to emit light simultaneously, or can be used for an R-LED die, a G-LED die, and a B -It may be used as an element for a display device that emits light in full color by adjusting the balance of the LED die.

  In an additive color mixed LED device, an R-LED die, a G-LED die, and a B-LED die are usually mounted and arranged in a plane on a single circuit board. At this time, light emission of each color may appear to be separated, and in order to perform additive color mixing, a diffusion plate or the like is disposed on the light emitting surface. That is, since the LED dies are dispersedly arranged to emit light, it is difficult to increase the color mixing property.

  In order to solve this drawback, there has been proposed an LED device in which R-LED dies, G-LED dies, and B-LED dies are stacked to superimpose light emission points to improve color mixing (for example, Patent Documents). 1, Patent Document 2, Patent Document 3).

  In the LED device shown in FIG. 1 of Patent Document 1, R-LED dies, G-LED dies, and B-LED dies having the same area are stacked. At this time, the long wavelength light emitted from the lower LED die is transmitted through the upper LED die that emits short wavelength light, and absorption by the light emitting layer included in the upper LED die is reduced to improve efficiency. . As described above, this LED device enables white light emission or full color light emission while having good luminous efficiency and a small mounting area.

  In the LED device shown in FIG. 60 of Patent Document 2, the areas of the R-LED die, the G-LED die, and the B-LED die are sequentially set to small, medium, and large, and the B-LED having the largest area. G-LED dies and R-LED dies are stacked on the die. In this LED device, a light emitting layer is formed in a region where the lower LED die does not become a shadow of the upper LED die, thereby realizing a small and high luminance light source.

  In the LED device shown in FIG. 4 of Patent Document 3, an R-LED die and a B-LED die having the same area are stacked on a B-LED die, and a spacer is disposed between the LED dies. By this spacer, a hollow portion is formed between the LED dies, and heat generated by each LED die is released into the air by the hollow portion. In this manner, the LED device shown in FIG. 4 of Patent Document 3 prevents the light emission efficiency from decreasing and achieves high brightness.

JP 2002-43627 A (FIGS. 1 and 4) Japanese Patent No. 3378465 (FIG. 60) JP2011-192672A (FIG. 4)

  The LED devices shown in Patent Documents 1 to 3 suggested that the LED device can be reduced in size and brightness by stacking LED dies. However, since these LED devices combine R-LED dies, G-LED dies, and B-LED dies, it is difficult to balance R, G, and B when whitening, and the lifetime and aging of each LED die. The problem is that the changes are different from each other and that it is difficult to conceive a configuration other than the three-layer structure.

  Accordingly, an object of the present invention is to provide a semiconductor light emitting device in which, when a plurality of semiconductor light emitting elements are stacked to achieve miniaturization and luminance improvement, chromaticity and change with time are stable, and the number of layers to be stacked is not limited. To do.

  In order to achieve the above object, a semiconductor light emitting device according to the present invention is characterized in that a plurality of semiconductor light emitting elements are stacked on a circuit board having wiring electrodes, and a phosphor layer is interposed between the semiconductor light emitting elements. And

  According to the above configuration, all or most of the light emitted upward from the semiconductor light emitting element on the lower layer side is wavelength-converted to the longer wavelength side by the phosphor layer. Of the wavelength-converted light, the upward light is incident on the upper semiconductor light-emitting element, but is wavelength-converted to the longer wavelength side, so it is hardly reabsorbed by the light-emitting layer and passes through the upper semiconductor light-emitting element. To do. Moreover, even if it is incident on another phosphor layer, it passes through the phosphor layer without being absorbed by the phosphor. In this way, the light once wavelength-converted to the long wavelength side and going upward is directly emitted from the semiconductor light emitting device. That is, even if the semiconductor light emitting elements are stacked, if the phosphor layer is provided between the semiconductor light emitting elements, the wavelength-converted light can be efficiently extracted.

  At this time, the semiconductor light emitting element may emit light at a relatively short wavelength. That is, since the phosphor emits white light (or longer wavelength), three types of semiconductor light emitting devices are prepared: a semiconductor light emitting device emitting red light, a semiconductor light emitting device emitting green light, and a semiconductor light emitting device emitting blue light. There is no need to do. For this reason, it is easy to balance the colors, and the change with time is equalized. There is no limit on the number of stacked semiconductor light emitting elements.

  A phosphor layer may be interposed between the lowermost semiconductor light emitting element of the plurality of semiconductor light emitting elements and the circuit board.

  According to the said structure, the light radiate | emitted from the semiconductor light emitting element of the lowest layer is converted into the long wavelength side by the fluorescent substance layer provided between the circuit boards. Of the light converted to the long wavelength side, the component that goes up as it is and the component that is reflected by the upper surface of the circuit board and goes up are hardly absorbed by the light emitting layer of the lowermost semiconductor light emitting device. Pass through and head upward. By adding this component, the amount of light emitted from the semiconductor light emitting device can be increased.

  Of the plurality of semiconductor light emitting elements, the lowermost semiconductor light emitting element is preferably flip-chip mounted on the wiring electrode on the circuit board.

  According to the above configuration, the lowermost semiconductor light emitting element is flip-chip mounted on the wiring electrode on the circuit board, and the upper semiconductor light emitting element is wire bonded to the wiring electrode on the circuit board. Since flip chip mounting does not require a wire for connection, the mounting area is reduced, so that the semiconductor light emitting device can reduce the wire bonding process and improve the mounting efficiency.

  A dichroic mirror is disposed on the lower surface of a part of the plurality of semiconductor light emitting elements, and the dichroic mirror reflects light having a wavelength shorter than the emission wavelength of the semiconductor light emitting element on which the dichroic mirror is disposed. It is preferable to have a characteristic of transmitting light having a long wavelength.

  According to the above configuration, the short wavelength light emitted downward by the semiconductor light emitting element provided with the dichroic mirror is reflected upward by the dichroic mirror. At this time, the upward component of the light emitted from the semiconductor light emitting element and the phosphor layer below the dichroic mirror passes through the dichroic mirror as it is. As a result, the light emitting component directed downward from the semiconductor light emitting element in which the dichroic mirror is substantially disposed is eliminated, so that the emission efficiency as the semiconductor light emitting device is improved.

  A dichroic mirror is disposed on an upper surface of a part of the plurality of semiconductor light emitting elements, and the dichroic mirror transmits light having a wavelength shorter than the light emission wavelength of the semiconductor light emitting element on which the dichroic mirror is disposed. It is desirable to have a characteristic of reflecting light having a long wavelength.

  According to the above configuration, the light having a short wavelength emitted upward from the semiconductor light emitting element provided with the dichroic mirror passes through the dichroic mirror and enters the phosphor layer above the dichroic mirror. Here, the long wavelength light which is converted in wavelength by the phosphor layer and goes downward is reflected by the dichroic mirror and goes upward. Similarly, when light having a short wavelength emitted downward from the semiconductor light emitting element above the dichroic mirror through the phosphor layer is converted into light having a long wavelength by the phosphor layer, the light converted to this long wavelength The component going downward is reflected by the dichroic mirror and goes upward. In this way, light reflected by the dichroic mirror and added upward is added, so that the emission efficiency of the semiconductor light emitting device is improved.

  As described above, according to the semiconductor light-emitting device of the present invention, even if a plurality of semiconductor light-emitting elements are stacked in order to reduce the size and improve the luminance, the chromaticity and the change with time are stable, and the number of stacked layers can be eliminated. .

It is sectional drawing of the LED apparatus 10 in 1st Embodiment of this invention. It is a top view of the LED apparatus 10 shown in FIG. It is sectional drawing of the LED apparatus 20 in 2nd Embodiment of this invention. It is sectional drawing of the LED apparatus 30 in 3rd Embodiment of this invention. It is sectional drawing of the LED apparatus 40 in 4th Embodiment of this invention. It is sectional drawing of the LED apparatus 50 in 5th Embodiment of this invention. It is sectional drawing of the LED apparatus 60 in 6th Embodiment of this invention.

(First embodiment)
The details of the present invention will be described below with reference to the drawings. 1 and 2 show a stacked LED device according to a first embodiment of the present invention. FIG. 1 is a sectional view of an LED device 10, FIG. 2 is a plan view, and FIG. It corresponds to.

  1 and 2, reference numeral 10 denotes an LED device, in which four layers of LED dies 1a, 1b1c, and 1d are interposed via three phosphor layers 2a, 2b, and 2c stacked between the LED dies 1a to 1d. The circuit board 3 is laminated. Each LED die 1a to 1d has a rectangular shape, the LED dies 1a and 1c are arranged in the same direction, and the LED dies 1b and 1d are arranged orthogonal to the LED dies 1a and 1c. The electrode pads provided on the short sides of the LED dies 1 a to 1 d are connected to wiring electrodes (not shown) formed on the circuit board 3 by wires 4.

  The LED device 10 uses a near-ultraviolet-emitting UV-LED die or a blue-emitting B-LED die having a short emission wavelength as the LED dies 1a to 1c, and emits a short wavelength of the LED die as the phosphor layers 2a to 2c. Is converted into light having a long wavelength. In this way, the short wavelength light emitted by the lower LED die is converted into long wavelength light by the upper phosphor layer, so that absorption when passing through the upper LED die is reduced. As a result, the LED device 10 emits mixed-color light in which short-wavelength light emitted by the uppermost (or uppermost layer side) LED die and long-wavelength light converted by the lower phosphor layer are mixed.

  Further, since the absorption spectrum of the phosphor layer is on the shorter wavelength side than the emission spectrum, the light converted to the wavelength side by the lower phosphor layer is difficult to be reabsorbed by the upper phosphor layer. As described above, when an LED die having a short wavelength emission is used as the LED die and the long wavelength conversion is performed with the phosphor layer, the number of LED die and phosphor layer to be stacked is not limited, and various combinations can be performed. It becomes like this.

  For example, the LED device 10 uses B-LED dies for all LED dies 1a, 1b, 1c, and 1d, and uses YAG phosphor layers for all the phosphor layers 2a, 2b, and 2c. The yellow light from the layers 2a, 2b, and 2c and the blue light of the uppermost B-LED die 1d can be mixed to emit white light. That is, it is only necessary to prepare two parts, ie, a B-LED die and a YAG phosphor layer as constituent parts, and the management of the members can be simplified. Further, by increasing the number of stacked layers, it is possible to achieve high brightness as an LED device.

  Further, in the LED device 10, the LED dies 1a, 1b, and 1c are UV-LED dies (LED dies that emit ultraviolet light), and only the uppermost LED die 1d is a blue-light B-LED die, and all phosphors. The layers 2a, 2b, and 2c may be YAG phosphor layers. In this case as well, a high-brightness white light LED device can be provided.

  Further, in the LED device 10, the LED dies 1a, 1b, 1c are UV-LED dies, only the uppermost LED die 1d is a blue-light B-LED die, and the phosphor layers 2a, 2b, 2c are red phosphors. It may be a combination of a layer and a green phosphor layer. In this case, a high-luminance white light LED device in which the R, G, and B components are balanced can be provided. Alternatively, all of the LED dies 1a to 1d may be UV-LED dies, and a phosphor layer that emits blue light may be added on the LED die 1d.

(Second Embodiment)
Next, an LED device according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a cross-sectional view of the LED device 20 of the second embodiment. The basic configuration is the same as that of the LED device 10 of the first embodiment shown in FIG. Description is omitted. The LED device 20 is different from the LED device 10 in that the fourth phosphor layer 2d is sandwiched between the lowermost LED die 1a and the circuit board 3. In the configuration of the LED device 20, as in the configuration of the LED device 10, B-LED dies are used for all the LED dies 1a, 1b, 1c, 1d, and YAG phosphor layers are used for the phosphor layers 2a, 2b, 2c. By using it, it is the same that the white light by the mixed color of the yellow light by each phosphor layer 2a, 2b, 2c and the blue light of the uppermost B-LED die 1d is emitted.

  As described above, the fourth phosphor layer 2d is provided between the lowermost LED die 1a and the circuit board 3 as described above, and this phosphor layer 2d is also a YAG phosphor layer similar to the other phosphor layers. It is. As a result, the light directed from the lowermost LED die 1a toward the circuit board 3 is wavelength-converted by the phosphor layer 2d, then reflected by the surface of the circuit board 3, and returns to the emission surface side of the LED device 20 (this In this case, it is preferable that the surface of the circuit board has good reflection characteristics). Therefore, as compared with the LED device 10, the LED device 20 can effectively utilize the light directed from the lowermost LED die 1a toward the circuit board 3 and has higher emission efficiency.

(Third embodiment)
Next, an LED device according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a cross-sectional view of the LED device 30 according to the third embodiment. The basic configuration is the same as that of the LED device 10 according to the first embodiment shown in FIG. Description is omitted. The LED device 30 is different from the LED device 10 in that a phosphor layer 2e is further laminated on the uppermost LED die 1d.

  In this LED device 30, UV LED dies are used for all LED dies 1a, 1b, 1c, and 1d, the phosphor layer 2a is a red phosphor layer, the phosphor layers 2b and 2c are green phosphor layers, and fluorescence. By using the blue phosphor layer for the body layer 2e, the LED device 30 that emits white light with a good color tone obtained by converting the wavelength of the light emitted from the UV-LED die by the R, G, B phosphor layers.

(Fourth embodiment)
Next, an LED device according to a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a cross-sectional view of the LED device 40 of the fourth embodiment. In the LED device 40, an embodiment in which one phosphor layer 2a is stacked between two LED dies 1a and 1b is shown. The lower-layer LED die 1a has lower surface electrodes 5a. 5b, which is flip-chip mounted on the wiring pattern of the circuit board 3. The upper LED die 1b has an electrode pad on the upper surface and is wire-bonded to the wiring pattern of the circuit board 3 by a wire 4. In the present embodiment, the lower surface electrodes 5a. A phosphor layer 2d is provided between the LED die 1a and the circuit board 3 around 5b.

  In the configuration of the LED device 40, the lowermost LED die 1a is flip-chip mounted on a wiring pattern on the circuit board 3, and the upper LED die 1b is wire-bonded to the wiring pattern on the circuit board 3. By adopting flip-chip mounting for the LED die 1a, a connecting wire is not required, so that the mounting area can be reduced. For the LED device 40, the wire bonding process is reduced and the mounting efficiency is improved. It is done.

  Various combinations of LED dies and phosphor layers in the LED device 40 are possible, but as an example, B-LED dies are used for the LED dies 1a and 1b in substantially the same manner as the LED device 10, and fluorescence By adopting a YAG phosphor layer for the body layers 2a and 2d, it is possible to efficiently emit white light by mixing yellow light from the phosphor layers 2a and 2d and blue light from the uppermost B-LED die 1b. Yes. Further, in the present embodiment, an example of a two-layer LED die configuration is shown, but it is a matter of course that an LED die and a phosphor layer may be further laminated.

(Fifth embodiment)
Next, an LED device according to a fifth embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a cross-sectional view of the LED device 50 according to the fifth embodiment of the present invention. The basic configuration is the same as that of the LED device 40 according to the fourth embodiment shown in FIG. The duplicated explanation is omitted. The LED device 50 is different from the LED device 40 in that the dichroic mirror 6 is disposed on the lower surface of the LED die 1b. It has a characteristic of reflecting short wavelength light and transmitting long wavelength light.

  According to the above configuration, the short wavelength light beam PS emitted downward by the LED die 1b provided with the dichroic mirror 6 is reflected by the dichroic mirror 6 and travels upward. At this time, the light beam PL going upward from the light emitted by the phosphor layer 2 a below the dichroic mirror 6 passes through the dichroic mirror 6 as it is. As a result, since the light emitting component directed downward from the LED die 1b in which the dichroic mirror 6 is substantially disposed is eliminated, the emission efficiency as the LED device is improved.

(Sixth embodiment)
Next, an LED device according to a sixth embodiment of the present invention will be described with reference to FIG.
FIG. 7 is a cross-sectional view of the LED device 60 of the sixth embodiment. The basic configuration is the same as that of the LED device 50 of the fifth embodiment shown in FIG. Description is omitted. The LED device 60 is different from the LED device 50 in that the dichroic mirror 7 is disposed on the upper surface of the LED die 1a. It has a characteristic of transmitting light having a short wavelength and reflecting light having a long wavelength.

  According to the above configuration, the short wavelength light beam PS emitted upward from the LED die 1a on which the dichroic mirror 7 is disposed passes through the dichroic mirror 7 and enters the phosphor layer 2a above the dichroic mirror 7 to emit fluorescence. Wavelength conversion is performed by the body layer 2a. In the phosphor layer 2a, long wavelength light (not shown) emitted by the light beam PS and traveling downward is reflected by the dichroic mirror 7 and travels upward. Similarly, light PL having a short wavelength emitted downward from the LED die 1b above the dichroic mirror 7 through the phosphor layer 2a is converted into light having a long wavelength by the phosphor layer 2a and converted to this long wavelength. Of the emitted light, the downward light beam PL is reflected by the dichroic mirror 7 and travels upward. In this way, light reflected from the dichroic mirror 7 and added upward is added, so that the emission efficiency of the LED device 60 is improved.

  In the LED devices 50 and 60 including the dichroic mirrors 6 and 7, various combinations of the LED die and the phosphor layer are possible as in the LED device 40. For example, similarly to the LED device 40, both the LED dies 1a and 1b use B-LED dies, and adopt a YAG phosphor layer for the phosphor layers 2a and 2d, so that yellow light from the phosphor layers 2a and 2d It is possible to efficiently emit white light by mixing with the blue light of the uppermost B-LED die 1b. In the present embodiment, an example of a two-layer LED die configuration is shown, but it is natural that the LED die and the phosphor layer may be further multilayered.

  As described above, according to the present invention, an LED die having a relatively short emission wavelength, such as a UV-LED die or a B-LED die, is used, and a phosphor layer is laminated between the LED dies. Miniaturization and high brightness can be achieved. Further, since there is no limit on the number of stacked layers, the luminance can be improved without increasing the arrangement area, and the color tone can be adjusted by changing various combinations of the phosphor layers. Furthermore, since the same LED die and the same phosphor layer can be used, the variation in characteristics can be reduced and the change with time can be made the same, so that the product can be stabilized as an LED device.

1a, 1b, 1c, 1d LED die 2a, 2b, 2c, 2d, 2e Phosphor layer 3 Circuit board 4 Wire 5a, 5b Bottom electrode 6, 7 Dichroic mirror 10, 20, 30, 40, 50, 60 LED device

Claims (5)

  A semiconductor light emitting device comprising a plurality of semiconductor light emitting elements stacked on a circuit board having wiring electrodes, and a phosphor layer interposed between the semiconductor light emitting elements.   2. The semiconductor light emitting device according to claim 1, wherein a phosphor layer is also interposed between a semiconductor light emitting element in the lowest layer among the plurality of semiconductor light emitting elements and the circuit board.   3. The semiconductor light emitting device according to claim 1, wherein a lowermost semiconductor light emitting element among the plurality of semiconductor light emitting elements is flip-chip mounted on a wiring electrode on the circuit board.   A dichroic mirror is disposed on the lower surface of a part of the plurality of semiconductor light emitting elements, and the dichroic mirror reflects light having a wavelength shorter than the emission wavelength of the semiconductor light emitting element on which the dichroic mirror is disposed. The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting device has a characteristic of transmitting light having a long wavelength. A dichroic mirror is disposed on an upper surface of a part of the plurality of semiconductor light emitting elements, and the dichroic mirror transmits light having a wavelength shorter than the light emission wavelength of the semiconductor light emitting element on which the dichroic mirror is disposed. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device has a characteristic of reflecting light having a long wavelength.

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