JP6569217B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light-emitting device using a light-emitting element, and more particularly to a surface-mounted light-emitting device in which a protective element is mounted.

For light emitting devices used as various light sources, light emitting elements such as light emitting diodes and semiconductor lasers are used.
In such a light-emitting device, a protective element such as a Zener diode may be mounted on the light-emitting device in order to protect the light-emitting element from destruction due to overvoltage. When such a protective element is disposed adjacent to the light emitting element, light from the light emitting element is absorbed by the protective element or shielded by the protective element, thereby reducing light extraction efficiency as a whole of the light emitting device. Sometimes.
Therefore, as in the light emitting device disclosed in Patent Document 1 below, it has been proposed to provide a recess for placing the protective element on the surface opposite to the surface on which the light emitting element is placed. The light-emitting device configured in this manner has sufficient brightness by arranging the light-emitting element at substantially the center of the light-emitting device without the light from the light-emitting element being absorbed by the protective element or shielded by the protective element. While being held, it is possible to obtain a small surface mount light emitting device with anti-static measures.

JP 2001-36140 A JP 2007-227882 A

  However, in the light emitting device disclosed in Patent Document 1, since the mold resin is filled in the concave portion for placing the protective element provided in the region immediately below the light emitting element, sufficient heat dissipation of the light emitting device can be secured. However, there is a problem that the input power must be controlled.

  A light-emitting device according to an embodiment of the present invention has been made in view of the above problems, and in a light-emitting device equipped with a protective element, without reducing the light extraction efficiency of the light-emitting device and having heat dissipation properties. An object is to provide a secured light emitting device.

  A light-emitting device according to an embodiment of the present invention is a light-emitting device including a lead frame, a light-emitting element placed on the lead frame, and a resin package that holds the lead frame, and the lead frame includes: A first lead and a second lead that are spaced apart from each other in the resin package, the first lead and the second lead each having a first recess and a second recess, A protective element is placed in at least one of the first concave portion and the second concave portion, and the protective element and a protective element conductive member that electrically connects the protective element and the lead frame are the resin. It is covered with a package.

  A light-emitting device according to another embodiment of the present invention is a light-emitting device including a protection element, a lead frame, a light-emitting element placed on the lead frame, and a resin package that holds the lead frame. The lead frame has a recess for mounting the protection element, and the recess and the protection element are covered with the resin package.

  In the light emitting device in which the protective element is mounted, it is possible to provide a light emitting device in which heat dissipation is ensured without reducing light extraction efficiency.

1 is a plan view showing a light emitting device according to Embodiment 1. FIG. 2 is a bottom view showing the light emitting device according to Embodiment 1. FIG. 1 is a cross-sectional view illustrating a light emitting device according to Embodiment 1. FIG. 6 is a plan view showing a light emitting device according to Embodiment 2. FIG. 6 is a bottom view showing a light emitting device according to Embodiment 2. FIG. 6 is a cross-sectional view showing a light emitting device according to Embodiment 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the embodiment of the present invention, the resin package means having a resin for holding the lead frame. Moreover, that the recess and the protection element are covered with the resin package means that the recess and the protection element are covered with the resin portion of the resin package.

[Light Emitting Device 100 According to Embodiment 1]
1A, 1B, and 1C are a plan view, a cross-sectional view, and a bottom view, respectively, showing a light-emitting device 100 according to Embodiment 1. As shown in FIGS. 1A to 1C, the light emitting device 100 includes a lead frame 10, a light emitting element 21 placed on the lead frame 10, and a resin package 31 that holds the lead frame 10. Further, the lead frame 10 includes a first lead 11 and a second lead 12 that are spaced apart from each other in the resin package 31, and the light emitting element 21 is placed on the first lead 11. Each of the first lead 11 and the second lead 12 has a first recess 13 and a second recess 14 in a part thereof, and a protection element 41 is placed in the second recess 14. The protective element 41 and the protective element conductive member 51 that electrically connects the protective element 41 and the lead frame are covered with a resin package 31. That is, the protection element 41 and the protection element conductive member 51 are embedded in the resin package.

  With such a configuration, in the light emitting device including the protection element, the light emitted from the light emitting element 21 can be extracted outside without being absorbed by the protection element. Will improve. Furthermore, in the light emitting device 100 according to the first embodiment, since the region directly under the light emitting element is exposed from the resin package 31 on the back surface of the first lead on which the light emitting element is placed, the light emitting device with higher heat dissipation and It becomes possible to do.

  Hereinafter, it demonstrates in order.

(Lead frame)
The light emitting device 100 according to the first embodiment includes a lead frame 10. The lead frame includes a first lead on which the light emitting element 21 is placed and a second lead that is paired with the first lead. The first lead and the second lead each include a first recess 13 and a second lead in a part of each. Two recesses 14 are provided. The first concave portion 13 and the second concave portion 14 are provided to accommodate the protective element 41 and the protective element conductive member 51 for electrically connecting the protective element and the lead frame. In the first embodiment, the protection element 41 is placed in the second recess. The place where the protective element is placed is not limited to the second recess but may be in the first recess.

The lead frame is preferably a flat lead frame. The plate shape may be substantially plate shape, and may be a plate shape having a corrugated shape and fine irregularities on the surface of the plate shape.
A first recess and a second recess are formed in each of the first lead and the second lead of the flat lead frame. A protection element and a protection element conductive member are accommodated in the first recess and the second recess, respectively, and are covered with a resin package described later. For this reason, it is preferable that the depth of the recess is deeper than the combined height of the protection element and the protection element conductive member. The concave portion can be formed by punching using a press, etching, or the like.

  In the present specification, the “concave portion” is not limited to a case where the bottom surface of the concave portion is surrounded by a continuous inner side surface, and may be a concave portion in which a part of the inner side surface is opened. In the sense that it also contains the case of a thin-walled portion provided in.

It is preferable that a 1st recessed part and a 2nd recessed part are a pair of recessed part arrange | positioned facing each other. The pair of concave portions means that the first concave portion and the second concave portion are formed so as to straddle regions where the first lead and the second lead arranged to face each other face each other. Furthermore, it is more preferable that the first recess and the second recess are formed in a substantially symmetrical shape.
In the light emitting device 100, the first concave portion and the second concave portion are a pair of concave portions arranged to face each other, and each is provided at a corner portion of the first lead and the second lead. Not surrounded by Such a recess is preferable because the length of the protective element conductive member can be kept short.

  The depths of the recesses of the first recess and the second recess are not necessarily the same depth, and suitable depths can be determined depending on the height of the protection element, the material of the protection element conductive member, and the like. In addition, when using the protective element in which the positive and negative electrodes are arranged on the same surface, the protective element is placed on the first lead and the second lead by setting the concave depth of the first concave portion and the second concave portion to the same depth. Can be flip-chip mounted.

  It is preferable that the first concave portion and the second concave portion are disposed outside the bottom surface of the resin concave portion described later in plan view. Furthermore, it is preferable that the first recess and the second recess are arranged at the end of the lead frame in plan view. This arrangement is preferable because a region immediately below the light emitting element can be widely used as a heat dissipation region of the light emitting device.

The material of the lead frame is not particularly limited, but it is preferable that the lead frame be formed of a material that can supply appropriate power to the light emitting element. Moreover, it is preferable to form with a material with comparatively large thermal conductivity. By forming with such a material, the heat generated from the light emitting element 21 can be efficiently released. For example, a material having a thermal conductivity of about 200 W / (m · K) or more, a material having a relatively large mechanical strength, and a material that can be easily punched or etched are preferable. For example, metal such as copper, aluminum, gold, silver, tungsten, iron, nickel or iron-nickel alloy, phosphor bronze, iron-containing copper, etc. or a metal plating film such as silver, aluminum, copper, gold, etc. is applied to the surface. And the like.
The thickness of the lead frame is not particularly limited, but is preferably about 1.5 to 3 times the depth of the recess in consideration of the above-described recess depth and the like. Specifically, about 300-600 micrometers is mentioned.

(Light emitting element)
The light emitting element 21 is usually a light emitting diode. The light emitting element can be appropriately selected according to the purpose, such as its composition, emission color or wavelength, size, number, and the like. For example, as a blue and green light emitting element, a semiconductor layer such as ZnSe, nitride semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1), GaP, or the like is used. Examples of the red light emitting element include those using a semiconductor layer such as GaAlAs and AlInGaP.

The light emitting element is usually formed by stacking a semiconductor layer on a growth substrate (for example, a sapphire substrate). The growth substrate may have irregularities on the bonding surface with the semiconductor layer. This makes it possible to intentionally change the critical angle when the light emitted from the semiconductor layer hits the substrate and easily extract the light to the outside of the substrate.
In the light emitting element, the growth substrate may be removed after the semiconductor layers are stacked. The removal can be performed by, for example, polishing, LLO (Laser Lift Off), or the like.
The light emitting element may be either one having a pair of positive and negative electrodes on the same surface side with respect to the active layer or one having positive and negative electrodes on different sides with respect to the active layer.

  The light emitting element is usually placed on a lead, and a joining member is used for that purpose. For example, in the case of a light-emitting element having blue and green light emission and formed by growing a nitride-based semiconductor layer on a sapphire substrate, epoxy resin, silicone, or the like can be used. In consideration of deterioration from light or heat from the light emitting element, the back surface of the light emitting element may be metal-plated, or solder such as Au—Sn eutectic, low melting point metal, etc., without using resin. A material may be used. Furthermore, in the case of a light emitting element made of GaAs or the like and having electrodes formed on both sides thereof, such as a light emitting element that emits red light, die bonding may be performed using a conductive paste such as silver, gold, or palladium.

It is preferable that the light emitting element is disposed at substantially the center of the resin package in a plan view. By disposing the light emitting element substantially at the center, deviation from the center of the directivity of the light emitting device can be suppressed. Further, since the protective element is not exposed in the resin recess in which the light emitting element is placed, light emitted from the light emitting element can be extracted outside without being absorbed by the protective element. Extraction efficiency is improved.
Only one light emitting element may be placed in one light emitting device, but a plurality of light emitting elements may be placed. When a plurality of light emitting elements are mounted, the connection form is not particularly limited, such as parallel, series, or a combination thereof. By mounting a plurality of light emitting areas, the light emitting area can be increased, and the luminous flux can be improved.

  The light emitting device 100 according to Embodiment 1 includes a wire that connects a light emitting element and a lead. A pair of electrodes formed on the light emitting element is electrically connected to the lead by a wire in order to supply power to the light emitting element. The material, diameter, etc. of the wire in this case are not particularly limited, and those normally used in the field can be used. In particular, it is preferable that the ohmic property with the electrode of the light emitting element is good, the mechanical joining property is good, or the electrical conductivity and the thermal conductivity are good.

  As the wire, for example, a wire using a metal such as gold, silver, copper, platinum, or aluminum and an alloy thereof, or a wire coated with silver or a silver alloy can be used. Especially, when selecting a material with a high reflectance, silver, copper, lead, aluminum, platinum, or these alloys are preferable, and silver or a silver alloy is more preferable. Although the diameter of a wire is not specifically limited, About 10 micrometers-70 micrometers are mentioned. Preferably it is about 15-50 micrometers, More preferably, it is about 18-30 micrometers.

(Resin package)
The resin package is a member for holding the lead frame. The resin package includes a resin recess that houses the light emitting element. The light emitting element is disposed on the bottom surface of the resin recess. Specifically, the light emitting element is placed on a lead frame exposed at the bottom surface of the resin recess. The bottom surface of the resin recess is mainly composed of a first lead, a second lead, and a surface of the resin package that fills the space between the first lead and the second lead. In the first embodiment, the bottom surface of the resin recess is substantially flat, but, for example, a protrusion may be provided on the separation region. The side wall surface of the resin recess may be perpendicular to the bottom surface of the resin recess, but in order to efficiently extract the light emitted from the light emitting element, the opening becomes narrower as it approaches the bottom surface of the resin recess. It is preferable to be inclined. The resin recess, that is, the side wall of the recess can be saved, and for example, the resin package can be formed in a flat plate shape having the same thickness as the lead frame.

  The base material of the resin package is aliphatic polyamide resin, semi-aromatic polyamide resin, polyethylene terephthalate, polycyclohexane terephthalate, unsaturated polyester, liquid crystal polymer, polycarbonate resin, syndiotactic polystyrene, polyphenylene ether, polyphenylene sulfide, polyether sulfone resin Thermosetting resins such as thermoplastic resins such as polyether ketone resins and polyarylate resins, epoxy resins, epoxy modified resins, silicone resins, silicone modified resins, polybismaleimide triazine resins, polyimide resins, polyurethane resins, etc. . In these base materials, as a filler or a coloring pigment, glass, silica, titanium oxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium hydroxide, calcium silicate, magnesium silicate, wollastonite, Mica, zinc oxide, barium titanate, potassium titanate, aluminum borate, aluminum oxide, zinc oxide, silicon carbide, antimony oxide, zinc stannate, zinc borate, iron oxide, chromium oxide, manganese oxide, carbon black, etc. Particles or fibers can be incorporated.

(Protective element)
The protection element (1) suppresses a reverse voltage that can be applied to the light emitting element. (2) Suppressing application of a forward voltage equal to or higher than a predetermined voltage higher than the operating voltage of the light emitting element to the light emitting element. This means an element having at least one of the two functions. By using the protective element, the electrostatic withstand voltage of the light emitting device can be improved.

  The protective element disposed in the recess is not particularly limited and may be any known element mounted on the light emitting device. For example, a Zener diode, a capacitor, a varistor, a red light emitting diode, and the like can be given. If the positive and negative electrodes of the protective element are provided on the upper surface side and the back surface side, one electrode can be die-bonded to the lead frame via a bonding member, which is preferable because it can be formed relatively easily. . When positive and negative electrodes are provided on the same surface side, flip chip mounting can be performed via wire bonding or bumps. The flip chip mounting can be conducted by connecting each electrode to the lead frame across the first lead and the second lead.

(Protective element conductive member)
The protective element conductive member is a bonding member for mounting the protective element on the lead frame, a wire for electrically connecting the protective element and the lead frame, or the like.
As a bonding member for mounting the protective element on the lead frame and a wire for electrically connecting the protective element and the lead frame, the same member as the bonding member and the wire of the light emitting element described above can be used. .

(Sealing resin)
In the light emitting device 100 according to the first embodiment, the resin package has a resin recess that houses the light emitting element, and the resin resin recess is filled with the sealing resin 61. The sealing resin is a member that seals part of the light emitting element, the wire, and the lead to protect it from dust, smoke, moisture, external force, and the like. The material of the sealing resin is preferably a material having an insulating property and capable of transmitting light emitted from the light emitting element (preferably a transmittance of 70% or more). Specific examples include an epoxy resin, a silicone resin, a silicone-modified resin, a phenol resin, a polycarbonate resin, an acrylic resin, a TPX resin, a polynorbornene resin, or a hybrid resin containing one or more of these resins. Of these, silicone resins and epoxy resins are preferred.

The sealing resin may contain a diffusing agent or a phosphor. The diffusing material diffuses light, can reduce the directivity from the light emitting element, and can increase the viewing angle. The phosphor can convert the wavelength of light emitted from the light emitting element.
As the diffusing material, those known in the art can be used. Specifically, silica, titanium oxide, zirconium oxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium hydroxide, calcium silicate, zinc oxide, barium titanate, aluminum oxide, iron oxide, chromium oxide, Examples thereof include manganese oxide, glass, and carbon black.

As the phosphor, those known in the art can be used. Specifically, yttrium-aluminum-garnet (YAG) phosphors activated with cerium, lutetium-aluminum-garnet (LAG) phosphors activated with cerium, nitrogen-containing with europium and / or chromium Calcium aluminosilicate (CaO—Al ₂ O ₃ —SiO ₂ ) phosphor, europium activated silicate ((Sr, Ba) ₂ SiO ₄ ) phosphor, β sialon phosphor, CASN phosphor and SCASN phosphor And nitride-based phosphors such as KSF-based phosphors (K ₂ SiF ₆ : Mn) and sulfide-based phosphors. When the light emitting device is used for a backlight of a liquid crystal display or the like, a phosphor that is excited by blue light and emits red light (for example, KSF phosphor) and a phosphor that emits green light (for example, β sialon phosphor) are used. It is preferable. Thereby, the color reproduction range of the display using a light-emitting device can be expanded. Moreover, when used for illumination etc., the element which light-emits blue-green, and a red fluorescent substance can be used in combination.

  For example, the phosphor preferably has a center particle size of 50 μm or less. The central particle size can be measured and calculated by a commercially available particle measuring device or particle size distribution measuring device. In particular, when YAG or the like is used as the phosphor, a bulk body (for example, a plate-like body) in which these ultrafine particles are dispersed and sintered extremely uniformly is preferable. With such a form, a high degree of transparency can be ensured by reducing voids and impurity layers as a single crystal structure and / or a polycrystalline structure.

The phosphor may be, for example, a so-called nanocrystal or a light-emitting substance called a quantum dot. Examples of these materials include semiconductor materials such as II-VI, III-V, and IV-VI semiconductors. Specifically, CdSe, core-shell CdS _x Se _1-x / ZnS, and GaP Examples include highly dispersed particles of size. Examples of such a phosphor include a particle size of about 1 to 20 nm (10 to 50 atoms). By using such a phosphor, internal scattering can be suppressed and the light transmittance can be further improved. Since the quantum dot phosphor is unstable, it may be surface modified or stabilized with a resin such as PMMA (polymethyl methacrylate). These may be a bulk body (for example, a plate-like body) mixed and molded with a transparent resin (for example, an epoxy resin, a silicone resin, etc.), or a plate-like body sealed with a transparent resin between glass plates. May be.

  In addition, you may use 2 or more types of sealing resin as needed.

  As described above, in the light emitting device 100 according to the first embodiment, the light emitted from the light emitting element 21 can be extracted outside without being absorbed by the protective element, so that the light extraction efficiency is improved. Furthermore, since the region directly under the light emitting element is exposed from the resin package 31 on the back surface of the first lead on which the light emitting element is placed, a light emitting device with higher heat dissipation can be obtained.

[Light Emitting Device 200 According to Embodiment 2]
2A, 2B, and 2C are a plan view, a cross-sectional view, and a bottom view, respectively, showing the light-emitting device 200 according to Embodiment 2. As shown in FIGS. 2A to 2C, the light emitting device 200 is surrounded by an inner side surface where the concave portion 15 on which the protective element 41 is placed is provided on the light emitting surface side of the light emitting device and the bottom surface of the concave portion 15 is continuous. This is different from the light emitting device 100 according to the first embodiment in which the first concave portion and the second concave portion are provided on the back side facing the light emitting surface of the light emitting device.

  Similarly to the light emitting device 100 according to the first embodiment, the light emitting device 200 according to the second embodiment can extract the light emitted from the light emitting element 21 to the outside without being absorbed by the protective element. Efficiency is improved. Furthermore, since the region directly under the light emitting element is exposed from the resin package 31 on the back surface of the first lead on which the light emitting element is placed, a light emitting device with higher heat dissipation can be obtained.

  Although the embodiments have been described above, these descriptions are merely examples, and do not limit the configurations described in the claims.

  The light emitting device according to the embodiment of the present invention is applied to various lighting devices such as a light source for illumination, a backlight light source such as an LED display and a mobile phone, a traffic light, an illumination type switch, an in-vehicle light source, an amusement, various sensors and various indicators. Can be used.

DESCRIPTION OF SYMBOLS 10 Lead frame 11 1st lead 12 2nd lead 13 1st recessed part 14 2nd recessed part 15 Recessed part 21 Light emitting element 31 Resin package 32 Resin recessed part 41 Protection element 51 Protection element conductive member

Claims (3)

A protective element;
A lead frame;
A light emitting device mounted on the surface of the lead frame;
A resin package for holding the lead frame,
The resin package includes a resin recess that houses the light emitting element,
The light emitting element is disposed on the bottom surface of the resin recess,
In the lead frame, a region immediately below the light emitting element is exposed on the back surface of the resin package, and the protection element is placed only on the front surface side of the lead frame and outside the bottom surface of the resin recess in plan view. Having a recess to
The resin recess has a side wall portion having a side wall surface on the surface side of the lead frame,
The side wall surface is inclined so that the opening becomes narrower as it approaches the bottom surface of the resin recess,
The light emitting device, wherein the recess and the protection element are covered with a side wall portion of the resin package. The light emitting device according to claim 1 , wherein the recess has a depth greater than a height of the protection element. The light emitting device, light emitting device according to claim 1 or claim 2 is positioned substantially at the center of the resin package in plan view.

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