JP6589259B2 - Light emitting element and light emitting device using the same - Google Patents

Description

  The present disclosure relates to a light emitting element and a light emitting device using the same.

  A part of the light emitted from the semiconductor light emitting element, comprising a semiconductor light emitting element (LED chip) having a transparent insulating substrate and a semiconductor layer formed on the lower surface thereof, and a connection electrode for connecting to the mother substrate As a semiconductor light emitting device for converting the wavelength of a semiconductor light emitting device, a semiconductor light emitting device having a white reflecting member covering a side portion of the semiconductor light emitting element is known (see Patent Document 1).

JP 2012-227470 A

  However, in the above conventional light emitting device, the bonding member used when mounting on the mother board protrudes from the gap between the LED chip or the white reflective member and the mounting board and spreads outside the LED chip. There was a problem that the light emitted from was absorbed.

  The above problem is solved by the following means.

  An LED chip having a pair of electrodes on the lower surface, and light that covers the side surfaces of the LED chip and covers the surface of the LED chip so that the upper surface of the LED chip and the lower surfaces of the pair of electrodes included in the LED chip are exposed. A light emitting device comprising a reflective member, wherein the light reflective member is provided with a recess on a lower surface thereof.

  According to the above-described light emitting element, light absorption by the bonding member can be suppressed and the light extraction efficiency of the light emitting device can be improved.

It is the schematic diagram of the light-emitting device which concerns on Embodiment 1, (a) is a perspective view, (b) is AA sectional drawing in (a), (c) is formed in the dent X and the upper surface of a mounting substrate. It is a figure explaining the positional relationship of a mounting electrode. It is the schematic diagram of the light-emitting device which concerns on Embodiment 2, (a) is a perspective view, (b) is AA sectional drawing in (a), (c) is formed in the dent X and the upper surface of a mounting substrate. It is a figure explaining the positional relationship of a mounting electrode.

[Light Emitting Device According to Embodiment 1]
1A and 1B are schematic views of a light-emitting device according to Embodiment 1, wherein FIG. 1A is a perspective view, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. It is a figure explaining the positional relationship of the mounting electrode formed in FIG.

  As illustrated in FIG. 1, a light emitting device 100 according to Embodiment 1 includes a light emitting element 10, a mounting substrate 20 on which the light emitting element 10 is mounted, a bonding member 30 that bonds the light emitting element 10 and the mounting substrate 20, and It is the light-emitting device provided with. The light emitting element 10 includes an LED chip 12 including a pair of electrodes 121 and 122 on the lower surface, a side surface of the LED chip 12, and an upper surface of the LED chip 12 and a lower surface of the pair of electrodes 121 and 122 included in the LED chip 12. A light reflective member 14 covering the surface of the LED chip 12 so as to be exposed. According to the first embodiment, even if the bonding member 30 protrudes from the gap between the LED chip 10 and the mounting substrate 20, the side surface of the LED chip 12 is not covered with the bonding member 30. Therefore, light absorption by the bonding member 30 can be suppressed, and the light extraction efficiency of the light emitting device can be improved. Details will be described below.

(Light emitting element 10)
The light emitting element 10 includes an LED chip 12 and a light reflecting member 14. The light emitting element 10 may be mounted on the mounting substrate 20 as a top surface light emitting element as shown in FIG. 1 or may be mounted on the mounting substrate 20 as a side surface light emitting element.

<LED chip 12>
As the LED chip 12, for example, one having a pair of electrodes 121 and 122 formed on the lower surface of a substantially rectangular semiconductor layer 120 (also the lower surface of the LED chip 12) can be used. The semiconductor layer 120 includes, for example, an n-type semiconductor layer 120a, an active layer 120b as a light emitting layer, and a p-type semiconductor layer 120c. The n-type semiconductor layer 120a, the active layer 120b, and the p-type semiconductor layer 120c include, for example, ZnSe, a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) GaP or the like can be used. Note that the active layer 120b is a layer that emits light, but the wavelength of the light emitted from the active layer 120b is not limited.

  The LED chip 12 may include a growth substrate 120d on which the semiconductor layer 120 is grown as shown in FIG. However, the LED chip 12 may be configured not to include the growth substrate 120d. In this case, for example, after the semiconductor layer 120 is grown on the growth substrate 120d, the laser lift-off method, the metric method, and the chemical lift-off method are used. The growth substrate 120d is peeled off or removed from the semiconductor layer 120 by a method or a polishing method.

  As described above, the pair of electrodes 121 and 122 included in the LED chip 12 are formed on the lower surface of the semiconductor layer 120 (also the lower surface of the LED chip 12). Here, the electrode 121 of the pair of electrodes 121 and 122 is, for example, a p-side electrode of the LED chip 12, and the electrode 122 of the pair of electrodes 121 and 122 is, for example, an n-side electrode of the LED chip 12. Note that the lower surface of the LED chip 12 faces the upper surface of the mounting substrate 20 when the light emitting element 10 is mounted on the mounting substrate 20. The upper surface (light emitting surface) of the LED chip 12 is a light emitting surface from which light from the LED chip 12 is extracted, and is provided on the side opposite to the lower surface of the LED chip 12.

  The pair of electrodes 121 and 122 included in the LED chip 12 are bonded to the mounting electrodes 201 and 202 provided on the upper surface of the mounting substrate 20 via the bonding member 30, so that the light emitting element 10 is mounted on the mounting substrate 20. The That is, among the mounting electrodes 201 and 202 provided on the upper surface of the mounting substrate 20, when the mounting electrode 201 is a positive electrode and the mounting electrode 202 is a negative electrode, for example, the electrode 121 of the LED chip 12 is the mounting electrode 201 of the mounting substrate 20. The electrode 122 of the LED chip 12 is bonded to the mounting electrode 202 of the mounting substrate 20 via the bonding member 30.

  The shape and material of the pair of electrodes 121 and 122 included in the LED chip 12 can be variously changed. However, since the pair of electrodes 121 and 122 are members bonded to the mounting electrodes 201 and 202, it is preferable that the pair of electrodes 121 and 122 have a material / shape that considers wettability with the bonding member 30 and bonding reliability. The pair of electrodes 121 and 122 can be formed by sputtering, vapor deposition, plating, or the like.

<Light Reflective Member 14>
The light reflective member 14 covers the surface of the LED chip 12, that is, at least the outer surface of the LED chip 12 so that the upper surface of the LED chip 12 and the lower surfaces of the pair of electrodes 121 and 122 are exposed. Further, the outer surfaces of the pair of electrodes 121 and 122 are also optionally covered. This prevents the bonding member 30 from contacting the side surfaces of the LED chip 12 (particularly the side surfaces of the pair of electrodes 121 and 122). In addition, since the light reflecting member 14 is provided not only on the side surface of the LED chip 12 but also on the lower side, light transmitted downward from the LED chip 12 is reflected by the light reflecting member 14. Transmission of light from below the LED chip 12 is suppressed. In this case, the light reflective member 14 may cover the lower surface of the LED chip 12 where the pair of electrodes 121 and 122 are not formed. Further, the inner surfaces of the pair of electrodes 121 and 122 may be covered.

  A recess X is provided on the lower surface of the light reflective member 14, more specifically on the lower surface of the outer peripheral portion of the light reflective member 14. The bonding member 30 protruding from the gap between the LED chip 12 and the mounting substrate 20 is accommodated in the recess X, and the side surface of the LED chip 12 is not covered by the bonding member 30. When the recess X is provided on the lower surface of the light reflective member 14, the protrusion of the bonding member 30 can be reduced and the area required for mounting one light emitting element 10 can be reduced. Can be mounted on the mounting substrate 20, the distance between the light emitting elements 10 (mounting pitch) can be reduced. Further, when the plurality of light emitting elements 10 are arranged and mounted on the mounting substrate 20, the light absorption of the light emitting device 100 as a whole can be reduced and the light extraction efficiency of the light emitting device 100 can be increased. This is because when a plurality of light emitting elements 10 are arranged and mounted on the mounting substrate 20, light emitted from a certain light emitting element 10 may be absorbed by the bonding member 30 of the adjacent light emitting element 10. This is because the protrusion of the bonding member 30 can be reduced and the light absorption by the bonding member 30 can be reduced if the ten bonding members 30 are accommodated in the recesses X of the adjacent light emitting elements 10. .

  The shape of the recess X is not particularly limited as long as it can accommodate the joining member 30. For example, the recess X is provided, for example, in a hole shape having an opening on the lower surface of the light emitting element 10 or on the lower surface of the outer peripheral portion of the light reflecting member 14 as shown in FIG. It can have a stepped shape. When the recess X has such a stepped shape, the bonding member 30 is moved from the lower surface of the light emitting element 10 to the side surface side of the light emitting element 10 without confining the bonding member 30 in the hole formed in the lower surface of the light emitting element 10. Since it can form continuously, the joint strength with respect to the mounting substrate 20 of the light emitting element 10 can be raised. Further, if the bonding member 30 is continuously formed from the lower surface of the light emitting element 10 to the side surface side of the light emitting element 10, the bonding inspection and confirmation of the light emitting element 10 with respect to the mounting substrate 20 can be easily performed by visual recognition. .

  The recess X is preferably formed along the outer peripheral edge of the mounting electrodes 201 and 202 formed on the upper surface of the mounting substrate 20 (there may be a shift that can be said to be an error. The same applies hereinafter). In this way, the bonding member 30 can be easily provided on the upper surfaces of the mounting electrodes 201 and 202, so that the bonding strength and heat dissipation of the light emitting element 10 to the mounting substrate 20 can be increased. Further, when the bonding member 30 is solder, a self-alignment effect can be obtained between the light emitting element 10 and the mounting electrodes 201 and 202, but the recess X extends along the outer peripheral edge of the mounting electrodes 201 and 202. If formed, the dent X does not hinder the self-alignment effect (or the degree of hindrance is reduced), so that the light emitting element 10 can be easily and accurately mounted on the mounting substrate 20. .

  The recess X can be formed, for example, by selectively removing or patterning the light reflective member 14 into the shape of the recess X. Further, when the light reflective member 14 is obtained by curing a liquid material (for example, when the light reflective member 14 uses a thermosetting resin as a base material), a pair of LED chips 12 is used. With the electrodes 121 and 122 facing upward, the material of the light reflecting member 14 is applied to the bottom surface of the LED chip 12, so that the material of the light reflecting member 14 is raised on the pair of electrodes 121 and 122. Thus, the light reflective member 14 having the recess X can be formed.

  For the light reflective member 14, for example, a white member containing a white filler or white powder can be used. As an example of such a white member, a resin having insulating properties, high light reflectance, and high heat resistance and light resistance can be given. More specifically, for example, silicone resins containing titanium oxide, silicon oxide, barium sulfate, aluminum oxide or the like, modified types thereof, resists, and the like can be given as examples.

(Mounting board 20)
As the mounting board 20, for example, a printed board in which mounting electrodes are provided on an insulating base material such as glass epoxy, polyimide, or ceramic can be used. The mounting substrate 20 may be a flexible substrate. As the mounting electrodes 201 and 202 provided on the upper surface of the mounting substrate 20, for example, a thin film such as copper or aluminum can be used. The light emitting element 10 is mounted on the mounting substrate 20 by, for example, flip chip mounting. The shape of the mounting substrate 20 is not particularly limited, and for example, a plate shape, a strip shape, a film shape, a tape shape, and the like are examples of the shape of the mounting substrate 20.

(Jointing member 30)
As the bonding member 30, for example, an adhesive (see FIG. 2) based on a metal material such as solder (see FIG. 1) or a resin such as a conductive resin or an anisotropic conductive paste can be used. The joining member 30 is provided in a gap between the LED chip 12 and the mounting substrate 20 (a space where the lower surface of the LED chip 12 and the upper surface of the mounting substrate 20 face each other), and joins the light emitting element 10 and the mounting substrate 20.

(Phosphor layer 16)
As shown in FIG. 1, a phosphor layer 16 covering the LED chip 12 may be provided on the upper surface of the LED chip 12. In this case, the light reflecting member 14 preferably covers the lower surface of the phosphor layer 16 (more specifically, the region of the lower surface of the phosphor layer 16 that does not face the upper surface of the LED chip 12). By doing so, it is possible to reduce light from being emitted from the lower surface of the phosphor layer 16 to the lower side of the light emitting element 10, so that the light extraction efficiency of the light emitting device 100 can be increased. When the lower surface of the phosphor layer 16 (more specifically, the region of the lower surface of the phosphor layer 16 that does not face the upper surface of the LED chip 12) is covered with the light reflective member 14, the recess X is formed. The lower surface of the phosphor layer 16 is preferably provided below the region covered with the light reflective member 14. In this way, since the distance between the phosphor layer 16 and the bonding member 30 is reduced, the heat dissipation from the phosphor layer 16 to the mounting substrate 20 via the bonding member 30 can be improved. In this case, it is preferable to use a material (for example, a metal material such as solder) having higher thermal conductivity than the light reflective member 14 as the bonding member 30.

  As the phosphor layer 16, for example, a translucent resin mixed with a phosphor can be used. Such a translucent resin can be formed by, for example, coating, printing, sticking a sheet-like phosphor-containing molded body, and coating by spraying a slurry in which a phosphor, a resin, and a solvent are mixed. The phosphor layer 16 may be formed of only phosphor without being mixed with resin or the like. In addition, as the phosphor layer 16, a plate in which a phosphor is mixed with glass, a plate-like member formed by sintering a phosphor, or the like can be used.

The phosphor constituting the phosphor layer 16 is a fluorescent member that emits light having a different wavelength by absorbing at least part of the light emitted from the LED chip 12 as a wavelength conversion member. Specific examples of such fluorescent members include yttrium aluminum garnet (YAG) phosphors, nitride phosphors mainly activated by lanthanoid elements such as Eu and Ce, and oxynitride materials. A phosphor or the like can be used. For example, when blue light is emitted from the LED chip 12, a phosphor that emits light in the wavelength range from green to yellow (eg, YAG phosphor, LAG phosphor, M ₂ SiO ₄ : Eu ( M is a silicate phosphor of Sr, Ca, Ba, etc., or a combination thereof), or a phosphor that emits light in the red wavelength region (eg, (Sr, Ca) AlSiN ₃ : SCASN type such as Eu) A phosphor, a CASN phosphor such as CaAlSiN ₃ : Eu, a SrAlSiN ₃ : Eu, a KSF phosphor, or a combination thereof may be used in a combination or a blending ratio suitable for a desired color tone. In addition, in addition to a phosphor that emits light in the green or yellow wavelength region, a color rendering property and color reproducibility can be improved by using a phosphor that emits light in the red wavelength region.

  Of the entire surface of the LED chip 12, the surface not covered with the light reflective member 14 is preferably covered with a protective layer. For example, the above-described phosphor layer 16 and a translucent layer that does not include the phosphor (for example, a translucent resin or a translucent inorganic layer) are examples of the protective layer. In this way, the LED chip 12 can be protected. In addition, as an example of the thickness of such a protective layer or / and the fluorescent substance layer 16, 10-200 micrometers can be mentioned, for example.

  As described above, according to the first embodiment, even if the bonding member 30 protrudes from the gap between the LED chip 10 and the mounting substrate 20, the side surface of the LED chip 12 is not covered with the bonding member 30. Therefore, according to the first embodiment, since light absorption by the bonding member 30 is suppressed, the light extraction efficiency of the light emitting device can be improved.

  The first embodiment is a light-emitting device in which the side surface of the LED chip is covered with the light-reflecting member 14, and therefore is particularly preferably applied when the light-emitting element 10 is configured as a chip-size package (CSP: Chip Size Package). Can do. The chip size package is “a package that is equal to or slightly larger than the size of the LED chip 12”.

[Light Emitting Device According to Embodiment 2]
2A and 2B are schematic views of a light-emitting device according to Embodiment 2, wherein FIG. 2A is a perspective view, FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A, and FIG. It is a figure explaining the positional relationship of the mounting electrode formed in FIG.

  As shown in FIG. 2, the light emitting device 200 according to the second embodiment is an embodiment in which a metal material is used as the joining member 30 in that an adhesive based on a resin is used as the joining member 30. 1 is different from the light emitting device 100 according to 1. Also in the second embodiment, the light extraction efficiency of the light emitting device can be improved as in the first embodiment. In the case of using a resin-based adhesive as the bonding member 30, unlike the case of using a metal material as the bonding member 30, the mounting electrodes 201 and 202 are not formed in the entire area of the upper surface of the mounting substrate 20. The joining member 30 is also formed in the region. Below, the joining member 30 different from Embodiment 1 is demonstrated. Since members other than the joining member 30 are the same as those in the first embodiment, the description thereof is omitted.

(Jointing member 30)
In the second embodiment, an anisotropic conductive paste in which conductive particles are contained in a base material of a thermosetting resin (for example, an epoxy resin) is used as the bonding member 30. When such an anisotropic conductive paste is used, it is necessary to press the light emitting element 10 against the mounting substrate 20 when the light emitting element 10 is bonded to the mounting substrate 20. Easy to spread. However, according to the second embodiment, the spread of the joining member 30 is reduced by the recess X.

  When the joining member 30 is a metal material such as solder as in the first embodiment, the joining member 30 easily protrudes from the gap between the LED chip 12 and the mounting substrate 20 because the wettability with the light reflective member 14 is low. However, if the bonding member 30 protruding from the gap between the LED chip 12 and the mounting substrate 20 is accommodated in the recess X, the LED chip 12 and the mounting substrate are used even when these members are used as the bonding member 30. The amount of the joining member 30 that protrudes from the gap 20 is reduced. As described above, when the bonding member 30 is solder, the recess X does not hinder the self-alignment effect by forming the recess X along the outer peripheral edge of the mounting electrodes 201 and 202. (Or because the degree of hindrance is reduced), the light emitting element 10 can be easily and accurately mounted on the mounting substrate 20.

  On the other hand, when the joining member 30 is a resin-based material, such as an anisotropic conductive paste or silver paste, as in the second embodiment, the wettability with the light reflective member 14 is high. The member 30 tends to adhere to the side surface of the light reflective member 14. However, if the joining member 30 that protrudes from the gap between the LED chip 12 and the mounting substrate 20 is accommodated in the recess X, even if these members are used as the joining member 30, The amount of the bonding member 30 attached to the side surface is reduced.

  In addition, when the mounting electrode is provided on the film-like base material as described above as the mounting substrate 20 and a flexible substrate having flexibility is used, the mounting substrate 20 emits light when the mounting substrate 20 is bent. The element 10 may be peeled off or the light emitting element 10 may be destroyed. However, as in the second embodiment, the bonding member 30 is made of a resin-based material, such as an anisotropic conductive paste or silver paste, and the bonding member 30 is recessed from the lower side of the light emitting element 10 into the recess of the light emitting element 10. By providing and bonding up to X, the mounting substrate 20 and the light emitting element 10 can be firmly bonded, and the reliability of the light emitting device can be improved.

  The embodiments have been described above. However, these descriptions relate to examples, and the configurations described in the claims are not limited by these descriptions.

DESCRIPTION OF SYMBOLS 10 Light emitting element 12 LED chip 120 Semiconductor layer 120a n-type semiconductor layer 120b active layer 120c p-type semiconductor layer 120d Growth substrate 121 Electrode 122 Electrode 14 Light reflective member 16 Phosphor layer 20 Mounting substrate 201 Mounting electrode 202 Mounting electrode 30 Bonding member 100 light emitting device 200 light emitting device X dent

Claims (13)

An LED chip comprising a semiconductor layer and a pair of electrodes formed on the lower surface of the semiconductor layer;
As the lower surface of the upper surface and the pair of electrodes of the LED chip is exposed, with a, a light reflecting member covering at least an outer surface and inner surface of the side and lower surfaces and the pair of electrodes of said semiconductor layer A light emitting device,
A recess having a step shape is provided on the lower surface of the outer peripheral portion of the light reflecting member ,
The light-emitting element is characterized in that the recess is not formed on an inner surface of the pair of electrodes, but is formed along an outer peripheral edge of the pair of electrodes . A phosphor layer covering the upper surface of the LED chip;
The light reflecting member covers a lower surface of the phosphor layer;
The light-emitting element according to claim 1 . The light emitting device according to claim 2 , wherein the recess is provided below a region covered with the light reflective member on a lower surface of the phosphor layer. 4. The light emitting device according to claim 1, wherein the light reflective member further covers a portion of the lower surface of the LED chip where the pair of electrodes are not formed. 5. 5. The light emitting device according to claim 1 , wherein the light reflective member covers all of the side surfaces of the pair of electrodes. The recess is provided on the lower surface of the light reflecting member so that the material of the light reflecting member is pushed up with the respective side surfaces of the pair of electrodes facing the lower surface of the pair of electrodes. The light emitting element according to claim 1 . An LED chip and a pair of electrodes formed on a lower surface of the semiconductor layer and the semiconductor layer, such that the upper surface of the LED chip and the lower surface of the pair of electrodes is exposed, said the side surface and the lower surface of said semiconductor layer A light-reflective member that covers at least the outer side surface and the inner side surface of the pair of electrodes;
A mounting substrate on which the light emitting element is mounted;
A bonding member for bonding the light emitting element and the mounting substrate,
A recess having a step shape is provided on the lower surface of the outer peripheral portion of the light reflecting member,
The recess is not formed on the inner surface of the pair of electrodes, but is formed along the outer peripheral edge of the pair of electrodes,
At least a part of a portion of the bonding member that protrudes from a gap between the LED chip and the mounting substrate is accommodated in the recess. The light emitting device according to claim 7 , wherein the light reflective member further covers a portion of the lower surface of the LED chip where the pair of electrodes are not formed. The light emitting device according to claim 7 , wherein the light reflective member covers all of the side surfaces of the pair of electrodes. A mounting electrode is provided on the upper surface of the mounting substrate,
The recess is formed along the outer peripheral edge of the mounting electrode.
The light emitting device according to claim 7 , wherein the light emitting device is a light emitting device. The light-emitting device according to claim 7 , wherein the joining member is one of solder, conductive resin, and anisotropic conductive paste. The light emitting device according to claim 7, wherein the light emitting element is a chip size package. The recess is provided on the lower surface of the light reflecting member so that the material of the light reflecting member is pushed up with the respective side surfaces of the pair of electrodes facing the lower surface of the pair of electrodes. The light emitting device according to any one of claims 7 to 12 .

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