JP2019003978A - Semiconductor light-emitting device - Google Patents

Abstract

To provide a semiconductor light-emitting device capable of preventing generation of cracks even when a silicone resin is exposed to a high temperature.SOLUTION: A semiconductor light-emitting device has: a substrate 20; a light-emitting element 30 placed on the substrate; a first silicone resin 40 placed on the substrate so as to cover the light-emitting element; and a second silicone resin 50 placed on the substrate so as to cover the first silicone resin. The first silicone resin has a hardness within a first hardness range. The second silicone resin has a hardness within a second hardness range beyond the first hardness range.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor light emitting device.

  A semiconductor light emitting device equipped with a light emitting element such as an LED (Light Emitting Diode) is used for illumination or the like. In such a semiconductor light emitting device, after the light emitting element is mounted on the substrate, it is electrically connected to the substrate by a bonding wire and sealed with resin.

  As such a semiconductor light emitting device, for example, a support substrate having a recess, a light emitting element disposed in the recess, a sealing layer filled in the recess so as to seal the light emitting element, An optical lens layer formed on the sealing layer so as to cover the concave portion, the sealing layer mainly comprising a silicone gel having a penetration of 10 to 200, and Patent Document 1 discloses a light emitting device in which the optical lens layer is mainly composed of silicone rubber having a hardness of 30 to 97 (JIS type A hardness meter; 23 ° C.).

JP 2007-180284 A

  In the light emitting device of Patent Document 1, the sealing layer is heated by heat generated from the light emitting element and heat generated from the phosphor particles. For this reason, deterioration of the silicone resin is accelerated and a crack is generated in the sealing layer.

  When a crack is generated in the sealing layer, air enters from the crack and there is no heat dissipation path toward the optical lens layer, and the temperature of the sealing layer increases. In addition, when an air layer is formed, the reflection of light increases. For this reason, the temperature of the phosphor particles also increases, and as a result, there is a problem that the deterioration of the silicone resin is further accelerated.

  Further, when the sealing layer is heated to a high temperature, the temperature is transmitted to the optical lens layer, and a crack is generated in the optical lens layer.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor light emitting device capable of preventing the occurrence of cracks even when a silicone resin is exposed to a high temperature.

  In order to achieve the above-described object, a semiconductor light emitting device according to the present invention includes a substrate, a light emitting element placed on the substrate, and a first placed on the substrate so as to cover the light emitting element. And a second silicone resin placed on the substrate so as to cover the first silicone resin, wherein the first silicone resin is within a first hardness range. The second silicone resin has a hardness within a second hardness range exceeding the first hardness range.

1 is a top view of a semiconductor light emitting device according to Example 1. FIG. It is the sectional view on the AA line of FIG. 6 is a cross-sectional view illustrating another configuration example of the semiconductor light emitting device according to Example 1. FIG. 6 is a top view of a semiconductor light emitting device according to Example 2. FIG. It is the BB sectional view taken on the line of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description and the accompanying drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

  As shown in FIGS. 1 and 2, the semiconductor light emitting device 10 covers a mounting substrate 20 as a substrate, a light emitting element 30 placed on the main surface 21 of the mounting substrate 20, and the light emitting element 30. A first silicone resin 40 placed on the mounting substrate 20; and a second silicone resin 50 placed on the mounting substrate 20 so as to cover the first silicone resin 40. It is configured.

  The mounting substrate 20 is made of a ceramic material such as alumina or AlN. The mounting substrate 20 includes a connection electrode 22 that is electrically connected to the light emitting element 30. A wiring (not shown) for connecting the light emitting element 30 and a power source (not shown) is provided on the surface of the mounting substrate 20.

  There are two types of wirings, one that connects one end side of the power source and the connection electrode 22 and one that connects the other end side of the power source and the light emitting element 30.

  The light emitting element 30 is placed on the central portion of the mounting substrate 20. The light emitting element 30 includes a semiconductor structure layer 31 and a support substrate 32 that supports the semiconductor structure layer 31.

  The semiconductor structure layer 31 has a surface electrode 34 provided on the upper surface (light extraction surface 33) side, and a back electrode (not shown) provided on the surface of the semiconductor structure layer 31 on the support substrate 32 side.

  The support substrate 32 is made of a conductive material such as Si and SiC. The support substrate 32 is fixed to the mounting substrate 20 by using, for example, a conductive adhesive such as a die attach agent.

  The surface electrode 34 and the connection electrode 22 are connected to one end side of the power source by wire bonding using a bonding wire 60 formed of gold or the like. The bonding wire 60 is entirely covered with the first silicone resin 40.

  The back electrode and the wiring of the mounting substrate 20 are connected to the other end side of the power supply via the support substrate 32.

Phosphor particles 70 are provided on the light emitting element 30. For example, the phosphor particles 70 are excited by blue light and emit yellow fluorescence. Such phosphor particles 70 include Ce-activated yttrium aluminum garnet (YAG: Ce), Ce-activated terbium aluminum garnet (TAG: Ce), orthosilicate phosphor ((BaSrCa) SiO ₄ , etc. ), Α sialon phosphors (Ca-α-SiAlON: Eu, etc.) and the like can be used.

  The first silicone resin 40 seals the phosphor particles 70 and is provided in contact with the light emitting element 30, the mounting substrate 20, and the second silicone resin 50. The first silicone resin 40 is formed in a hemispherical dome shape so as to protrude in a direction perpendicular to the main surface 21.

  As the first silicone resin 40, a dimethyl silicone resin or a phenyl silicone resin can be used.

  The first silicone resin 40 has a hardness within the first hardness range. As for the first hardness range, in the case of dimethyl silicone resin, the Shore A hardness is 10 or more and less than 60. In the case of phenyl silicone resin, the first hardness range has a Shore A hardness of 25 or more and less than 90.

  The first silicone resin 40 has a characteristic that the hardness changes due to the influence of heat generated from the light emitting element 30 or the like. The change in the hardness of the first silicone resin 40 is equal to or higher than the hardness before heat reception after the hardness before the heat reception decreases from the hardness before heat reception with the heat generation time of the light emitting element 30. Becomes higher.

  Table 1 shows changes in hardness when the first silicone resin 40 is placed on a hot plate at 250 ° C.

  The first silicone resin 40 whose hardness change was measured is two types of dimethyl silicone resins and phenyl silicone resins having different components. In Table 1, one dimethyl silicone resin is represented as dimethyl A, and the other dimethyl silicone resin is represented as dimethyl B. In Table 1, the phenyl silicone resin is described as phenyl A.

  As shown in Table 1, the first silicone resin 40 showed a softening tendency that the hardness of each resin was lower than the hardness before heating until 240 minutes after the start of heating. When the heating time was 670 minutes, dimethyl A became equivalent to the hardness before heating. Dimethyl B and phenyl A were higher in hardness than before the heating.

  Such a hardness characteristic of the first silicone resin 40 is based on the fact that the first silicone resin 40 receives a heat to cause a hydrolysis polymerization reaction. That is, the first silicone resin 40 has a characteristic that the reaction rate of the hydrolysis polymerization reaction is faster than the reaction rate of the polymerization. For this reason, the hardness of the first silicone resin 40 continues to decrease until the hydrolysis reaction converges. Next, the polymerization reaction becomes dominant, and the hardness of the resin increases again.

  The second silicone resin 50 is formed in a hemispherical dome shape so as to protrude in a direction perpendicular to the main surface 21. Note that the second silicone resin 50 may function as a lens layer.

  As the second silicone resin 50, a dimethyl silicone resin or a phenyl silicone resin can be used. The second silicone resin 50 has a hardness in a second hardness range that exceeds the first hardness range. The second hardness range is a Shore A hardness of 60 or more and 70 or less in the case of dimethyl silicone resin. In the case of phenyl silicone resin, the second hardness range is Shore A hardness 90 or more and Shore D hardness 75 or less. The second hardness range is a hardness range that does not overlap with the first hardness range.

  The second silicone resin 50 has a characteristic that the hardness changes due to the influence of heat generated from the light emitting element 30 or the like. The change in the hardness of the second silicone resin 50 increases with the heat receiving time from the hardness before the heat receiving.

  Table 2 shows the change in hardness when the second silicone resin 50 is placed on a hot plate at 250 ° C.

  The second silicone resin 50 whose hardness change was measured is three kinds of dimethyl silicone resins and phenyl silicone resins having different components. In Table 2, the dimethyl silicone resins are represented as dimethyl C, dimethyl D, and dimethyl E, respectively. In Table 2, the phenyl silicone resin is described as phenyl B.

  As shown in Table 2, the hardness of the second silicone resin 50 gradually increased from the start of heating until cracking occurred or until 670 minutes when the measurement of hardness change was completed.

  Such a hardness characteristic of the second silicone resin 50 is based on the fact that the hydrolysis polymerization reaction occurs when the second silicone resin 50 receives heat. That is, the second silicone resin 50 has a characteristic that the reaction rate of the hydrolysis polymerization reaction is slower than the reaction rate of the polymerization. For this reason, the polymerization reaction becomes dominant after the start of heating, and the hardness of the second silicone resin 50 continues to rise.

Thus, dimethyl silicone resin and phenyl silicone resin can be used for the first silicone resin 40 and the second silicone resin 50. Therefore, each of the first silicone resin 40 and the second silicone resin 50 can be combined as follows.
(1) When the first silicone resin 40 and the second silicone resin 50 are dimethyl silicone resins First hardness range: Shore A hardness 10 or more and less than 60 Second hardness range: Shore A hardness 60 or more and 70 or less (2) When the first silicone resin 40 is a dimethyl silicone resin and the second silicone resin 50 is a phenyl silicone resin First hardness range: Shore A hardness 10 or more and less than 60 Second hardness range: Shore A hardness of 90 or more and Shore D hardness of 75 or less (3) When the first silicone resin 40 is a phenyl silicone resin and the second silicone resin 50 is a dimethyl silicone resin First hardness range: Shore A hardness 25 or more and less than 60 Second hardness range: Shore A hardness 60 or more and 70 or less (4) First silicone resin 40 and first When the silicone resin 50 is a phenyl silicone resin, the first hardness range: Shore A hardness 25 or more and less than 90 Second hardness range: Shore A hardness 90 or more and Shore D hardness 75 or less As described above, By providing the first silicone resin 40 inside the second silicone resin 50, the second silicone resin 50 can be kept away from the light emitting element 30 and the phosphor particles 70 that are heat sources. For this reason, it becomes possible to prevent the second silicone resin 50 from cracking. Therefore, it is possible to extend the life of the semiconductor light emitting device 10.

  Even if the first silicone resin 40 is covered with the second silicone resin 50 and the first silicone resin 40 is softened by heat, the first silicone resin is covered by the second silicone resin 50 covering the first silicone resin 40. Since the deformation of 40 is suppressed, the position of the phosphor particles 70 can be made constant. Therefore, the chromaticity of the semiconductor light emitting device 10 can be made constant over a long period.

  By covering the entire bonding wire 60 with the first silicone resin 40 having a lower hardness than the second silicone resin 50, the force transmitted to the bonding wire 60 due to thermal deformation of the resin can be reduced. For this reason, disconnection of the bonding wire 60 can be prevented.

  A resin layer may be formed by the phosphor particles 70 and the silicone resin, and the first silicone resin 40 may be provided only on this resin layer.

  For example, as shown in FIG. 3, a resin layer 80 including phosphor particles 70 and first silicone resin 40 is placed on the mounting substrate 20 so as to cover the upper surface of the light emitting element 30. May be.

  In the above-described embodiment, one light emitting element 30 is provided on the mounting substrate 20. However, the mounting substrate 20 may be provided with a plurality of light emitting elements 30. Further, the semiconductor light emitting device 10 may have a housing.

  As shown in FIGS. 4 and 5, four light emitting elements 30 </ b> A to 30 </ b> D are provided on the main surface 21 of the mounting substrate 20. The mounting substrate 20 includes a housing 23 (cavity) that accommodates the light emitting elements 30A to 30D.

  The housing 23 is formed in a frame shape by the mounting substrate 20 and a frame-shaped reflector 24 provided so as to surround the periphery of the mounting substrate 20. In other words, the mounting substrate 20 is formed as a housing 23 having a recess.

  The reflector 24 is made of a so-called white resin in which a light scattering material is dispersed in a resin material such as silicone resin. The reflector is fixed to the mounting substrate 20 with an adhesive made of, for example, an epoxy resin.

  The light emitting element 30A is a light emitting element that outputs red. The light emitting element 30B is a light emitting element that outputs blue. The light emitting element 30C is a light emitting element that outputs green. The light emitting element 30D is a light emitting element that outputs white.

  The light emitting element 30A that outputs red is, for example, a light emitting element using aluminum gallium arsenide. The light emitting element 30B that outputs blue is, for example, a light emitting element using indium gallium nitride. The light emitting element 30C that outputs green is, for example, a light emitting element using indium gallium nitride. The light emitting element 30 </ b> D that outputs white is configured by providing phosphor particles 70 on the light emitting element 30 that outputs blue.

  On the main surface 21 of the mounting substrate 20, a region R <b> 1 in which a light emitting element 30 </ b> A that outputs red is provided, a region R <b> 2 in which a light emitting element 30 </ b> B that outputs blue is provided, and a light emitting element 30 </ b> C that outputs green is provided. The region R3 is provided, and the region R4 provided with the light emitting element 30D that outputs white is provided.

  In each of these regions R1 to R4, the first silicone resin 40 is individually provided so as to cover the respective light emitting elements 30A to 30D.

  The first silicone resin 40 is formed in a hemispherical dome shape so as to protrude from the main surface 21. Moreover, each 1st silicone resin 40 provided between each area | region R1-R4 is provided so that a mutual edge part may not contact | connect, respectively.

  In addition, the height H1 of the perpendicular direction with respect to the main surface 21 of the 1st silicone resin 40 which covers the light emitting element 30D which outputs white is with respect to the main surface 21 of the 1st silicone resin 40 which covers the other light emitting elements 30A-30C. It is lower than the height H2 in the vertical direction.

  The refractive index of the first silicone resin 40 may be, for example, 1.4 or more in the case of dimethyl silicone resin and 1.5 or more in the case of phenyl silicone resin.

  The second silicone resin 50 is provided so as to cover the entire regions R <b> 1 to R <b> 4 so as to embed the first silicone resin 40 and to fill the housing 23.

  The refractive index of the second silicone resin 50 is, for example, 1.4 or more in the case of dimethyl silicone resin, and 1.5 or more in the case of phenyl silicone resin, and the refractive index of the second silicone resin is the first silicone. It is preferable that the refractive index of the resin 40 be higher.

  As described above, according to the semiconductor light emitting device 10 according to the present embodiment, it is possible to prevent the second silicone resin 50 from being cracked as in the first and second embodiments. In addition, the life of the semiconductor light emitting device 10 can be extended. Furthermore, it becomes possible to make the chromaticity of the semiconductor light emitting device 10 constant over a long period of time.

  In addition, since the refractive index of the second silicone resin 50 is higher than the refractive index of the first silicone resin 40, the light of the other light emitting elements 30 can be reflected on the surface of the first silicone resin 40. . In addition, since the directivity of light emitted from the other light emitting elements 30 is narrowed, the amount of heat generated by the phosphor particles 70 can be suppressed. Therefore, it is possible to prevent the temperatures of the first silicone resin 40 and the second silicone resin 50 in the usage state of the semiconductor light emitting device 10 from becoming higher than necessary and to slow down the deterioration rate of these resins. . As a result, the life of the semiconductor light emitting device 10 can be extended.

  Further, the height H1 in the vertical direction with respect to the main surface 21 of the first silicone resin 40 covering the white light emitting element 30D is the height in the vertical direction with respect to the main surface 21 of the first silicone resin 40 covering the other light emitting elements 30. By being lower than the height H2, the phosphor particles 70 are less excited by light emitted from the other light emitting elements 30A to 30C, so that the calorific value of the phosphor particles 70 can be suppressed.

DESCRIPTION OF SYMBOLS 10 Semiconductor light-emitting device 20 Mounting board 21 Main surface 30 Light emitting element 40 1st silicone resin 50 2nd silicone resin 60 Bonding wire 70 Phosphor particle

Claims (9)

A substrate, a light emitting element placed on the substrate, a first silicone resin placed on the substrate so as to cover the light emitting element, and the first silicone resin so as to cover the first silicone resin A second silicone resin placed on the substrate,
The first silicone resin has a hardness within a first hardness range;
The semiconductor light emitting device according to claim 2, wherein the second silicone resin has a hardness in a second hardness range exceeding the first hardness range. The first silicone resin and the second silicone resin are dimethyl silicone resins,
In the first hardness range, the Shore A hardness is 10 or more and less than 60,
The semiconductor light emitting device according to claim 1, wherein the second hardness range is a hardness range of Shore A hardness of 60 to 70. The first silicone resin is a dimethyl silicone resin;
The second silicone resin is a phenyl silicone resin,
In the first hardness range, the Shore A hardness is 10 or more and less than 60,
2. The semiconductor light emitting device according to claim 1, wherein the second hardness range is a Shore A hardness of 90 or more and a Shore D hardness of 75 or less. The first silicone resin is a phenyl silicone resin,
The second silicone resin is a dimethyl silicone resin,
In the first hardness range, the Shore A hardness is 25 or more and less than 60,
The semiconductor light emitting device according to claim 1, wherein the second hardness range is a hardness range of Shore A hardness of 60 to 70. The first silicone resin and the second silicone resin are phenyl silicone resins,
In the first hardness range, the Shore A hardness is 25 or more and less than 90,
2. The semiconductor light emitting device according to claim 1, wherein the second hardness range is a Shore A hardness of 90 or more and a Shore D hardness of 75 or less. A plurality of the light emitting elements are provided on the main surface of the substrate,
The first silicone resin is provided in a plurality of regions on the main surface of the substrate so as to individually cover the light emitting elements,
The semiconductor light-emitting device according to claim 1, wherein the second silicone resin is provided so as to cover the entire plurality of regions.   The semiconductor light emitting device according to claim 6, wherein the second silicone resin has a higher refractive index than that of the first silicone resin. The first silicone resin on at least one light emitting element of the plurality of light emitting elements has a phosphor disposed on the at least one light emitting element,
The first silicone resin covering the at least one light emitting element is formed in a hemispherical shape so as to protrude from the main surface,
The height of the first silicone resin in the direction perpendicular to the main surface covering the light emitting element on which the phosphor on the at least one light emitting element is provided is the main height of the other first silicone resin. 8. The semiconductor light emitting device according to claim 6, wherein the semiconductor light emitting device is lower than a height in a direction perpendicular to the surface. The light emitting element and the substrate are electrically connected by a bonding wire,
The semiconductor light emitting device according to claim 1, wherein the bonding wire is entirely embedded in the first silicone resin.

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