JP2013110179A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED device having improved light distribution characteristics.SOLUTION: An LED device 10 comprises two rectangular LED dies 15, 16 including n-side electrodes 15a, 16a at positions displaced from the center of an electrode plane, and arranged at positions such that long sides of both LED dies 15, 16 become parallel with each other and the n-side electrodes 15a, 16a become rotationally symmetric with each other with respect to the center of the circuit board 12 when flip-chip bonded on a circuit board 12. As a result, light distribution of the LED device 10 becomes rotationally symmetric and radiation light becomes easy to handle.

Description

  The present invention relates to a semiconductor light emitting device in which a semiconductor light emitting element is mounted on a circuit board to form a package.

  2. Description of the Related Art Semiconductor light-emitting devices (hereinafter referred to as LED devices unless otherwise specified) in which a semiconductor light-emitting element cut out from a wafer (hereinafter referred to as an LED die unless otherwise specified) is packaged on a circuit board or the like are widely used. In a lighting device having a plurality of LED devices, improvement of the light distribution is one of the issues for improving the performance and quality, and the cause of the deterioration of the light distribution is the failure of the LED device itself. There is a uniform light distribution.

  For example, in the LED panel array 1 shown in FIG. 3 of Patent Document 1, each LED element 3 (LED device) emits light with a biased intensity (light distribution) distribution. It arrange | positions around the optical axis 72 at an angle which differs 90 degree | times, and it is trying to obtain uniform light distribution on a screen by superimposing the light emission of each LED element 3. FIG.

JP 2002-374004 A (FIG. 3)

  The illumination device (LED array panel 1) shown in FIG. 3 of Patent Document 1 has a plurality of LED devices (LED elements 3) arranged so as to be rotationally symmetric with each other, and the non-uniformity originally possessed by the LED device. By compensating the light distribution, the light distribution as an illuminating device is made uniform. However, when the light distribution of the LED device has a strong bias, in order to make the light distribution of the lighting device using the LED device uniform, there is a limit to improvement only by devising the relative arrangement relationship of the LED device. There is an entity that has to rely heavily on other optical members such as lenses and diffusers. That is, in order to easily improve the light distribution of the lighting device, the bias of the light distribution of the LED device itself must be reduced.

  Accordingly, an object of the present invention is to provide a semiconductor light emitting device with improved light distribution characteristics in order to solve this problem.

In order to solve the above problems, a semiconductor light emitting device of the present invention is a semiconductor light emitting device in which a plurality of semiconductor light emitting devices are mounted on a circuit board, and the semiconductor light emitting devices are covered with a resin or the like to form a package.
The plurality of semiconductor light emitting elements have the same shape,
The electrode arrangement on the electrode surface of the semiconductor light emitting device is not rotationally symmetric with respect to the center of the electrode surface,
The electrode of one of the semiconductor light emitting elements is disposed on the circuit board so as to be rotationally symmetric with the electrode of the other semiconductor light emitting element.

The semiconductor light emitting device has an electrode surface, and has an n-side electrode and a p-side electrode on the electrode surface. That is, an n-type semiconductor layer and a p-type semiconductor layer are stacked on an insulating substrate, a p-side electrode is provided on the p-type semiconductor layer, and a part of the p-type semiconductor layer is shaved and exposed. An n-side electrode is provided. Since the light emitting layer is at the boundary between the n-type semiconductor layer and the p-type semiconductor layer, the exposed region of the n-type semiconductor layer does not emit light. Therefore, the n-side electrode may be arranged at inconspicuous positions such as corners and sides of the electrode surface. As a result, the electrode arrangement on the electrode surface loses rotational symmetry with respect to the center of the electrode surface, and the semiconductor light emitting device The light distribution is strongly biased. When a plurality of semiconductor light emitting elements are prepared and mounted on a circuit board, the arrangement position of the n-side electrode of one semiconductor light emitting element is rotationally symmetric with the arrangement position of the n electrode of another semiconductor light emitting element on the circuit board. By doing so, the light distribution of the semiconductor light emitting device is also rotationally symmetric. Thus, even if a semiconductor light emitting element having a large bias in the light distribution is used, the light distribution of the semiconductor light emitting device becomes rotationally symmetric and improves.

  The electrode surface of the semiconductor light emitting element may be rectangular, the two semiconductor light emitting elements may be mounted on the circuit board, and the long sides of the two semiconductor light emitting elements may be parallel to each other.

  A reflective layer may be provided on the top, the circuit board may be rectangular, and the short side of the semiconductor light emitting element may be on the long side of the circuit board.

  A reflective layer may be provided on the top.

  Two of the semiconductor light emitting elements may be mounted on the circuit board, and the two semiconductor light emitting elements may be arranged linearly.

  The four semiconductor light emitting elements may be mounted on the circuit board, and the four semiconductor light emitting elements may be arranged in a cross shape.

  As described above, the semiconductor light-emitting device of the present invention is configured so that even if the light distribution of the semiconductor light-emitting elements is strongly biased, the semiconductor light-emitting devices are arranged on the circuit board so that the electrode positions of the semiconductor light-emitting elements are rotationally symmetric. The light distribution of the device is also rotationally symmetric and improved. As a result of improving the light distribution of the semiconductor device as described above, the illumination device using the semiconductor light emitting device of the present invention can obtain a uniform light distribution with a simple optical member such as a diffusion plate.

The front view of the LED device in 1st Embodiment of this invention. The perspective view of the state which removed the resin sealing material in the LED device shown in FIG. FIG. 2 is an explanatory diagram of an arrangement of LED dies included in the LED device shown in FIG. 1. FIG. 4 is a detailed cross-sectional view of a mounting portion of the LED die shown in FIG. 3. The front view of the LED device in 2nd Embodiment of this invention. Sectional drawing of the LED device shown in FIG. The arrangement plan of the LED die in a 3rd embodiment of the present invention. The layout plan of the LED die in a 4th embodiment of the present invention. The layout plan of the LED die in a 5th embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. For the sake of explanation, the scale of the members is changed as appropriate. Furthermore, the relationship with the invention specific matter described in the claims is described in parentheses.
(First embodiment)

  The appearance of the LED device 10 (semiconductor light-emitting device) in the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a front view of the LED device 10. A resin sealing material 11 is provided on the upper side of the circuit board 12, and two external connection electrodes 13 and 14 are provided on the lower side.

  The internal structure of the LED device 10 will be described with reference to FIG. FIG. 2 is a perspective view of the LED device 10 of FIG. 1 with the resin sealing member 11 removed. Two LED dies 15 and 16 (semiconductor light emitting elements) are arranged on the circuit board 12. The LED dies 15 and 16 are rectangular and are arranged so that their long sides are parallel to each other. The short sides of the LED dies 15 and 16 are arranged on a straight line and are on the long side of the rectangular circuit board 12. In FIG. 2, internal connection electrodes (described in FIG. 3) on the circuit board 12 are not shown.

  The internal structure of the LED device 10 will be described in more detail with reference to FIG. 3 is an explanatory view of the arrangement of the LED dies 15 and 16 included in the LED device 10 shown in FIG. 1, (a) is a plan view of the circuit board 12, and (b) is the LED die 15 on the circuit board 12. , 16 are flip-chip mounted states, and (c) is a sectional view taken along line AA in (b).

  As shown in (a), there are internal connection electrodes 31, 32 and 33 on the circuit board 12. The internal connection electrodes 31 and 33 cover the through-hole electrodes 34 and 35 and are connected to the external connection electrodes 13 and 14 through the through-hole electrodes 34 and 35, respectively. The internal connection electrode 32 is isolated on the circuit board 12.

  As shown in (b), the LED dies 15 and 16 are flip-chip mounted on the circuit board 12. In (b), the n-side electrodes 15a and 16a and the p-side electrodes 15b and 16b of the LED dies 15 and 16 formed on the lower surface are indicated by dotted lines. The p-side electrode 15 b of the LED die 15 is connected to the internal connection electrode 31, and the n-side electrode 15 a of the LED die 15 is connected to the internal connection electrode 32. Similarly, the p-side electrode 16 b of the LED die 16 is connected to the internal connection electrode 32, and the n-side electrode 16 a of the LED die 16 is connected to the internal connection electrode 33. That is, the LED die 15 and the LED die 16 are connected in series, the external connection electrode 13 is an anode of the LED device 10 (see FIGS. 1 and 2), and the external connection electrode 14 is a canode of the LED device 10. The n-side electrodes 15a and 16a are smaller than the p-side electrodes 15b and 16b because they are not directly related to light emission or heat dissipation.

  In the LED die 15 and the LED die 16, the electrode arrangement is rotationally symmetric about the center of the circuit board 12. That is, when the LED die 15 is rotated 180 degrees about this axis, the n-side electrode 15 a of the LED die 15 overlaps with the n-side electrode 16 a of the LED die 16. Similarly, the p-side electrode 15b of the LED die 15 also overlaps with the p-side electrode 16b of the LED die 16.

  The laminated structure concerning the LED dies 15 and 16 will be described with reference to (c). As described above, (c) is a sectional view taken along the line AA in (b), and the external connection electrodes 13 and 14 are visible on the lower surface of the circuit board 12 in this section. There is an internal connection electrode 32 on the upper surface of the circuit board 12, the n-side electrode 15 a of the LED die 15 is connected to the internal connection electrode 32, and the p-side electrode 16 b of the LED die 16 is simultaneously connected to the internal connection electrode 32. .

  The laminated structure around the connection portion of the LED die 15 will be described in more detail with reference to FIG. FIG. 4 is a cross-sectional view taken along the line BB in FIG. The LED die 15 includes a sapphire substrate 41 (insulating substrate), an n-type semiconductor layer 42, a p-type semiconductor layer 43, an insulating film 44, an n-side electrode 15a, and a p-side electrode 15b. An n-type semiconductor layer 42 is formed under the sapphire substrate 41, and a p-type semiconductor layer 43 is formed under the n-type semiconductor layer 42. The insulating film 44 covers the n-type semiconductor layer 42 and the p-type semiconductor layer 43 except for the opening. In the drawing, the p-type semiconductor layer 43 and the p-side electrode 15b are connected in the opening on the left side of the insulating film 44, and the n-type semiconductor layer 42 and the n-side electrode 15a are connected in the opening on the right side. The p-side electrode 15b and the n-side electrode 15a are connected to the internal connection electrode 31 and the internal connection electrode 32 formed on the circuit board 12, respectively. In this cross section, only the external connection electrode 13 is visible.

  The sapphire substrate 41 is a transparent insulating substrate and has a thickness of 80 to 120 μm. The n-type semiconductor layer 42 includes a GaN buffer layer and an n-type GaN layer and has a thickness of about 5 μm. The p-type semiconductor layer 43 is composed of a metal multilayer film including a reflective layer and an atomic diffusion prevention layer and a p-type GaN layer, and has a thickness of about 1 μm. Although not shown, the light emitting layer is at the boundary between the p-type semiconductor layer 43 and the n-type semiconductor layer 42, and the planar shape is substantially the same as that of the p-type semiconductor layer 43. The insulating film 44 is made of SiO2 or polyimide and has a thickness of about several hundred nm to 1 [mu] m. The n-side electrode 15a and the p-side electrode 15b are bumps having Au or Cu as a core, and are formed by electrolytic plating and have a thickness of about 10 to 30 μm. The internal connection electrodes 31 and 32 and the external connection electrode 13 are copper foils plated with Au and Ni and have a thickness of several μm to several tens of μm. The member of the circuit board 12 has a thickness of several tens of μm to several hundreds of μm, and is selected from resin, ceramics, metal and the like in consideration of thermal conductivity, reflectance, and the like.

  Next, the light emission characteristics of the LED device 10 (see FIGS. 1 and 2) will be described with reference to FIGS. As shown in FIG. 4, in the LED die 15, a part of the p-type semiconductor layer 43 is cut away to expose the n-type semiconductor layer 42 from the p-type semiconductor layer 43. Since this exposed portion does not emit light, it is made as small as possible. That is, in FIG. 3B, the region occupied by the n-side electrodes 15a and 16a and its peripheral portion do not emit light. As a result, in the LED device 10, the vicinity of the n-side electrodes 15 a and 16 a becomes dark, resulting in uneven emission characteristics.

  If the n-side electrodes 15a and 16a are both on the upper side of the circuit board 12 in FIG. 3B, the emitted light on the upper side becomes extremely weak. On the other hand, in this embodiment, the n-side electrode 15a is disposed on the lower side of the circuit board 12 and the n-side electrode 16a is disposed on the upper side of the circuit board 12 as shown in FIG. In this way, the n-side electrode 15a and the n-side electrode 16a do not interfere with each other, and the distribution of the emitted light (light distribution) does not extremely decrease. Further, since the orientation distribution is rotationally symmetric with respect to the center of the circuit board 12, the lighting device incorporating the LED device 10 can easily correct the light distribution with a simple optical member such as a diffusion plate.

  As described above, even if the n-side electrodes 15a and 16a of the LED dies 15 and 16 are at positions deviating from the center of the electrode surface, and the LED dies 15 and 16 have a light distribution with a strong bias, In the device 10, since the n-side electrodes 15a and 16a are rotationally symmetric with respect to the center of the circuit board 12, the light distribution is also rotationally symmetric and the bias is reduced. The LED device 10 is easy to handle because the light distribution is rotationally symmetric when incorporated in a lighting device. If the resin sealing material 11 that covers the LED dies 15 and 16 is made to contain a fluorescent material, the emission of the fluorescent material is isotropic, so that the uneven distribution of light distribution is further reduced.

In the LED device 10 of this embodiment, the LED dies 15 and 16 are flip-chip mounted. However, the mounting method is not limited to flip-chip mounting, and may be face-up mounting in which the circuit board and the electrode surface are not opposed. In the case of face-up mounting, the wire bonding shadow also causes the light distribution to be biased, but if the LED die is arranged so that the n-side and p-side electrodes are rotationally symmetric, the wire is also rotationally symmetric. The same effect as in the present embodiment can be obtained. Further, the LED device 10 uses the plate-like circuit board 12 provided with the electrode layer, but the circuit board may be a lead frame.
(Second Embodiment)

In the LED device 10 shown in FIG. 1 and the like, when the circuit board 12 is on the lower side, even if the plane is rotationally symmetric, strong radiated light appears on the upper side, and the radiated light rapidly increases as the azimuth angle increases. It tends to have a distribution distribution that weakens. In general, a lens is used to widen the light distribution, but the lens shape is often complicated when trying to obtain a wide and uniform light distribution for an LED device that is not a point light source. Further, when the LED device and the lens are stacked, there is a problem that the lighting device becomes thick. In response to these problems, an LED device that forms a reflective layer on the top and emits light only from the side surface is prepared, and a reflector or a light guide plate is disposed on the side of the LED device to make the lighting device thinner. This method eliminates the need for a lens on the LED device, so that the cost can be reduced. Therefore, as a second embodiment, an LED device 50 having a reflective layer on the top will be described with reference to FIGS. 5 and 6.

  The appearance of the LED device 50 will be described with reference to FIG. FIG. 5 is a front view of the LED device 50. A resin sealing material 11 is provided on the upper side of the circuit board 12, and two external connection electrodes 13 and 14 are provided on the lower side. The resin sealing material 11, the circuit board 12, and the external connection electrodes 13 and 14 are the same as those of the LED device 10 of FIG. 1, and the LED device 50 has a reflective layer 51 on the resin sealing material 11 with respect to the LED device 10. Only where it has. The reflective layer 51 is obtained by kneading reflective fine particles such as titanium oxide in a silicone resin, and has a thickness of about several tens of μm to 100 μm. The reflective layer 51 can be replaced with a metal layer or transflective reflection. In this case, it is more preferable that the reflective layer 51 has a diffusivity.

  The internal structure of the LED device 50 will be described with reference to FIG. FIG. 6 is a cross-sectional view of the LED device 50. FIG. 6 is obtained by adding the resin sealing material 11 and the reflective layer 51 to the cross-sectional view shown in FIG. Further, the arrangement of the upper surface of the circuit board 12 and the LED dies 15 and 16 is the same as that of the LED device 10 of the first embodiment (see FIGS. 3A and 3B).

  In FIG. 6, the long sides of the LED dies 15 and 16 (left and right direction in the figure) radiate light strongly toward the short side of the circuit board 12 (left and right direction in the figure), but before reaching the side surface of the LED device 50. The amount of light emitted from the short side of the circuit board 12 is reduced due to the direction change of the light beam due to the diffuse reflection by the reflection layer 51 and other losses. On the other hand, on the short sides of the LED dies 15 and 16 (front and back directions in the figure), the light emission amount is small due to the fact that the portions related to light emission are short and the n-side electrodes 15a and 16a (see FIG. 3) are present. However, since the distance to the long side of the circuit board 12 is short, the amount of light emitted from the LED device 50 is less attenuated. Further, the light emitted upward from the LED dies 15 and 16 is distributed to the short side and the long side of the LED device 50 by the diffuse reflection of the reflective layer 51, so that the light emitted from the short side and the long side of the LED device 50 is emitted. It works to correct the unevenness of the light.

That is, in the LED device 50, not only the light distribution is improved by arranging the n-side electrodes 15a, 16a and the p-side electrodes 15b, 16b of the LED dies 15, 16 to be rotationally symmetric, The reflective layer 51 disposed on the side is intended to make the light distribution in the side surface direction uniform. Furthermore, the fact that the long sides of the circuit board 12 and the short sides of the LED dies 15 and 16 are close also attempts to make the light distribution uniform. As described above, in the LED device 50, the horizontal orientation distribution is improved.
(Third embodiment)

  In the LED devices 10 and 50 according to the first and second embodiments, rectangular LED dies 15 and 16 are arranged in parallel on the circuit board 12, and the direction from the p-side electrode 15b toward the n-side electrode 15a and the p-side electrode The direction from 16b to the n-side electrode 16a was the reverse direction (see FIG. 3B). However, in order to improve the orientation distribution, the electrodes of one LED die and the electrodes of the other LED die may be arranged in a rotationally symmetrical manner. Therefore, the arrangement is not limited to the arrangement of the LED dies 15 and 16 as described above. FIG. 7 shows another arrangement example as the third embodiment.

  FIG. 7 is a layout view of the LED dies 75 and 76 in the LED device 70 according to the third embodiment of the present invention. FIG. 7 shows an upper surface of the circuit board 72 in a state where a resin sealing material (not shown) is removed from the LED device 70. LED dies 75 and 76 are flip-chip mounted on the upper surface of the circuit board 72. The internal connection electrodes are not shown. The n-side electrodes 75a and 76a and the p-side electrodes 75b and 76b are indicated by dotted lines.

As shown in FIG. 7, the LED dies 75 and 76 have n-side electrodes 75a and 76a at the corners, and the remaining regions surround the n-side electrodes 75a and 76a and occupy a large area. There is. The n-side and p-side electrodes 75 a and 75 b of the LED die 75 and the n-side and p-side electrodes 76 a and 76 b of the LED die 76 are arranged so as to be rotationally symmetric about the center of the circuit board 72. At the same time, the LED dies 75 and 76 are linearly arranged in the horizontal direction of the figure.
(Fourth embodiment)

  In the LED devices 10, 50, 70 in the first to third embodiments, there are two LED dies 15, 16, 75, 76 mounted on the circuit boards 12, 72. However, the number of LED dies to be mounted on the circuit board is not limited to two because the electrodes of one LED die and the electrodes of the other LED die may be rotationally symmetrical and the orientation distribution may be rotationally symmetric. Accordingly, an LED device 80 including four LED dies 85 will be described as a fourth embodiment with reference to FIG.

  FIG. 8 is a layout view of the LED die 85 in the LED device 80 according to the fourth embodiment of the present invention. FIG. 8 shows an upper surface of the circuit board 82 in a state where a resin sealing material (not shown) is removed from the LED device 80. Four LED dies 85 are flip-chip mounted on the upper surface of the circuit board 82. The internal connection electrodes are not shown. The n-side and p-side electrodes 85a and 85b are indicated by dotted lines.

As shown in FIG. 8, the LED die 85 has an n-side electrode 85a at a corner and a p-side electrode 85b occupying a large area so as to surround the n-side electrode 85a in the remaining region. The n-side and p-side electrodes 85 a and 85 b of each LED die 85 are arranged so as to be rotationally symmetric about the center of the circuit board 82. At the same time, the four LED dies 85 are arranged in a cross shape.
(Fifth embodiment)

  In the LED devices 10, 50, 70, 80 according to the first to fourth embodiments, when the electrode arrangement is ignored, the LED dies 15, 16, 75, 76, 85 mounted on the circuit boards 12, 72, 82 are shown in FIG. 3 (b), as shown in FIGS. 7 and 8, when the circuit boards 12, 72, 82 are viewed from the top, they are arranged so as to be symmetric with respect to center lines (not shown) in the vertical and horizontal directions with respect to the outline. doing. However, since the electrodes of one LED die and the electrodes of another LED die may be rotationally symmetrical and the orientation distribution may be rotationally symmetric, the arrangement of the LED die mounted on the circuit board is not limited to line symmetry. Accordingly, an LED device 90 including four LED dies 95 will be described as a fifth embodiment with reference to FIG.

  FIG. 9 is a layout view of the LED die 95 in the LED device 90 according to the fifth embodiment of the present invention. FIG. 9 shows an upper surface of the circuit board 92 in a state where a resin sealing material (not shown) is removed from the LED device 90. Four LED dies 95 are flip-chip mounted on the upper surface of the circuit board 92. The internal connection electrodes are not shown. The n-side and p-side electrodes 95a and 95b are indicated by dotted lines.

  As shown in FIG. 9, the LED die 95 has an n-side electrode 95a on the short side and a p-side electrode 95b so as to occupy a large area in the remaining region. The n-side and p-side electrodes 95a and 95b of each LED die 95 are arranged so as to be rotationally symmetric with respect to the center of the circuit board 92, respectively. At this time, the arrangement of the four LED dies 95 is not line-symmetric.

10, 50, 70, 80, 90 ... LED device (semiconductor light emitting device),
11 ... Resin sealing material,
12, 72, 82, 92 ... circuit board,
13, 14 ... external connection electrodes,
15, 16, 75, 76, 85, 95 ... LED elements (semiconductor light emitting elements),
15a, 16a, 75a, 76a, 85a, 95a ... n-side electrode,
15b, 16b, 75b, 76b, 85b, 95b ... p-side electrode,
31, 32, 33 ... internal connection electrodes,
34, 35 ... through-hole electrodes,
41 ... sapphire substrate (insulating substrate),
42 ... n-type semiconductor layer,
43 ... p-type semiconductor layer,
44. Insulating film.

Claims (6)

In a semiconductor light emitting device in which a plurality of semiconductor light emitting elements are mounted on a circuit board and the semiconductor light emitting elements are covered with a resin or the like to form a package,
The plurality of semiconductor light emitting elements have the same shape,
The electrode arrangement on the electrode surface of the semiconductor light emitting device is not rotationally symmetric with respect to the center of the electrode surface,
A semiconductor light emitting device, wherein an electrode of one semiconductor light emitting element is disposed on the circuit board so as to be rotationally symmetric with an electrode of another semiconductor light emitting element.   2. The electrode surface of the semiconductor light emitting element is rectangular, the two semiconductor light emitting elements are mounted on the circuit board, and the long sides of the two semiconductor light emitting elements are parallel to each other. The semiconductor light-emitting device described in 1.   3. The semiconductor light emitting device according to claim 2, further comprising a reflective layer on an upper portion, wherein the circuit board is rectangular, and the short side of the semiconductor light emitting element is on the long side of the circuit board.   The semiconductor light emitting device according to claim 1, further comprising a reflective layer on an upper portion.   5. The semiconductor light emitting device according to claim 1, wherein the two semiconductor light emitting elements are mounted on the circuit board, and the two semiconductor light emitting elements are arranged in a straight line.   6. The semiconductor light emitting device according to claim 1, wherein the four semiconductor light emitting elements are mounted on the circuit board, and the four semiconductor light emitting elements are arranged in a cross shape.

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