JP5851680B2 - Light emitting module - Google Patents

Description

  The present invention relates to a light emitting module.

  In recent years, vehicle headlamps using semiconductor light emitting elements such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes) have been proposed (for example, see Patent Document 1). In a vehicle headlamp, it is necessary to irradiate white light in a white light region defined by the automotive headlamp standard (JIS D5500).

  As a method for generating white light using a semiconductor light emitting element, a method using a phosphor is often employed. For example, when the YAG phosphor is irradiated with blue light emitted from a blue LED as excitation light, white light can be obtained by mixing yellow light obtained as fluorescence and blue light transmitted through the phosphor.

JP 2004-241142 A

  By the way, the LED emits isotropically light emitted from the light emitting layer. When the light from the LED reaches the phosphor, the light is wavelength-converted and isotropically emitted as fluorescence. That is, not all light emitted from the LED light or the fluorescent light emitted from the phosphor is emitted in a desired irradiation direction. Therefore, the light emitted toward the opposite side to the desired irradiation direction out of the light emitted from the LED and the fluorescence emitted from the phosphor does not contribute to illumination.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for improving the utilization efficiency of light emitted from a semiconductor light emitting element.

  In order to solve the above problems, a light emitting module according to an aspect of the present invention includes a semiconductor light emitting element and a mounting substrate on which the semiconductor light emitting element is mounted. In the mounting substrate, a reflective film that reflects light emitted from the semiconductor light emitting element is formed on the side on which the semiconductor light emitting element is mounted. The reflective film is entirely made of an insulating inorganic material.

  According to this aspect, of the light emitted from the semiconductor light emitting element, the light directed to the mounting substrate is reflected by the reflective film and irradiated in a predetermined irradiation direction. Therefore, the light use efficiency can be improved. Moreover, since the reflection film is entirely made of an insulating inorganic material, deterioration due to light emitted from the semiconductor light emitting element is suppressed. For example, even when the semiconductor light emitting element is a high-brightness LED, deterioration is suppressed. Moreover, even if the light emitted from the LED is ultraviolet light or short-wavelength visible light, since the reflective film is mainly composed of an inorganic material, deterioration is suppressed as compared with the case where the reflective film contains a large amount of resin components, Reliability of the light emitting module is improved. In addition, since the deterioration of the reflective film is suppressed, the continuous lighting time of the light emitting module in the range satisfying the desired luminance is extended, and the lifetime is extended. Note that “the whole is made of an insulating inorganic material” means not only the case where it is made entirely of an inorganic material, but also the case where the inorganic material contains impurities that are mixed in the raw material manufacturing or film formation process. Also good.

  The reflective film may be made of an inorganic material having a refractive index of 1.4 or more. As a result, light traveling from the semiconductor light emitting element to the mounting substrate is easily reflected by the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved.

  The reflective film may be a multilayer film in which a first inorganic material having a refractive index of 1.4 or more and a second inorganic material having a refractive index higher than that of the first inorganic material are stacked. Thereby, the light traveling from the semiconductor light emitting element to the mounting substrate is more easily reflected by the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved. Further, the reflective film may be a multilayer film controlled to have a thickness of about ¼ wavelength of emitted light. In this case, the light utilization efficiency can be dramatically increased. The multilayer film may further include a layer made of a material having a refractive index different from that of the first inorganic material and the second inorganic material.

  The reflective film may have a surface roughness Ra on the side facing the semiconductor light emitting element of 0.1 μm to 80 μm. As a result, light traveling from the semiconductor light emitting element to the mounting substrate is diffusely reflected on the roughened surface of the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved.

  The semiconductor light emitting element may be flip-chip connected to the mounting substrate. The semiconductor light emitting device flip-chip connected to the mounting substrate is provided with protruding electrodes such as bumps between the mounting substrate. Therefore, part of the light generated in the semiconductor light emitting element is likely to be emitted from the gap between the protruding electrodes toward the mounting substrate. Therefore, by forming the above-described reflective film on the mounting substrate, the light directed toward the mounting substrate is reflected again toward the semiconductor light emitting element and irradiated forward from the emission surface of the semiconductor light emitting element. Therefore, in the case of such a configuration, the effect of improving the utilization efficiency of light emitted from the semiconductor light emitting element becomes more remarkable.

  A translucent underfill filled between the reflective film of the mounting substrate and the semiconductor light emitting element may be further provided. When there is a gap (air layer) between the mounting substrate and the semiconductor light emitting element, light is not easily extracted from the semiconductor light emitting element. Therefore, by filling the gap with a light-transmitting underfill, light is easily extracted from the semiconductor light emitting element.

  ADVANTAGE OF THE INVENTION According to this invention, the utilization efficiency of the light which a semiconductor light emitting element emits can be improved.

It is a schematic structure figure of the lamp body unit which constitutes the vehicular headlamp device concerning this embodiment. It is a figure which shows the structure of the 2nd lamp unit contained in the lamp main body unit of this Embodiment. It is the figure which put together the structure and brightness | luminance of the light emitting module which concern on each Example and each comparative example on the table | surface. It is sectional drawing which showed typically the principal part of the light emitting module which concerns on Example 1-1. It is sectional drawing which showed typically the principal part of the light emitting module which concerns on Example 4-1. It is sectional drawing which showed typically the principal part of the light emitting module which concerns on Example 5-1. It is sectional drawing which showed typically the principal part of the light emitting module which concerns on Example 6-1. It is sectional drawing which showed typically the principal part of the light emitting module which concerns on Example 7-1. It is sectional drawing of the lighting fixture which can employ | adopt the light emitting module which concerns on this Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  In recent years, various lighting devices using LEDs and LDs have been developed. Some of these lighting devices require high luminance as a characteristic. For example, when a light emitting module using an LED or LD as a light source is used for a vehicle headlight or a lighting fixture, higher brightness is required. Thus, as a result of intensive studies to achieve high luminance of the light emitting module, the present inventors have devised a light emitting module represented by the embodiment described below.

[Vehicle headlamp device]
First, an outline of a vehicle headlamp device (vehicle lamp) that is required to have high luminance will be described as a suitable application of a light emitting module according to an embodiment described later. The vehicle headlamp device according to the present embodiment includes a lamp unit that emits light capable of forming a partial region of a high beam light distribution pattern, and an irradiation control unit that controls the light irradiation state of the lamp unit. Prepare. And an irradiation control part controls the irradiation state of light so that the partial area | region of the light distribution pattern for high beams may be formed by the partial area | region divided | segmented into multiple at least by the vehicle width direction. In addition, the intensity of the irradiation light corresponding to each partial area is individually adjusted to switch between the high beam irradiation mode and the daytime lighting irradiation mode to form a light intensity distribution suitable for the high beam irradiation mode and a light intensity distribution suitable for the daytime lighting irradiation mode. . The light emitting module according to each embodiment can be applied not only to a lamp unit that forms a high beam light distribution pattern, but also to a lamp unit that forms a low beam light distribution pattern.

  FIG. 1 is a schematic structural diagram of a lamp body unit constituting the vehicle headlamp device according to the present embodiment. The vehicle headlamp device according to the present embodiment includes a pair of lamp body units at the left and right ends in the vehicle width direction of the front portion of the vehicle. And the irradiation as a vehicle headlamp apparatus is completed by superimposing the light distribution pattern irradiated from the left and right lamp body units in front of the vehicle. FIG. 1 shows a configuration of a lamp body unit 10 arranged on the right side of the left and right lamp body units. FIG. 1 shows a sectional view of the lamp body unit 10 cut from a horizontal plane and seen from above for easy understanding. The lamp body unit arranged on the left side has a symmetrical structure with the lamp body unit 10 arranged on the right side, and the basic structure is the same. Therefore, the description of the lamp body unit 10 disposed on the left side is omitted by describing the lamp body unit 10 disposed on the right side. In the following description, for the sake of convenience, the direction in which the light from the lamp is irradiated may be described as the vehicle front (front side) and the opposite side as the vehicle rear (rear side).

  The lamp body unit 10 includes a translucent cover 12, a lamp body 14, an extension 16, a first lamp unit 18, and a second lamp unit 20. The lamp body 14 is formed into a cup shape having a long and narrow opening with resin or the like. The translucent cover 12 is formed of a translucent resin or the like, and is attached to the lamp body 14 so as to close the opening of the lamp body 14. Thus, the lamp body 14 and the translucent cover 12 form a lamp chamber that is substantially a closed space, and the extension 16, the first lamp unit 18, and the second lamp unit 20 are disposed in the lamp chamber.

  The extension 16 has an opening for passing the irradiation light from the first lamp unit 18 and the second lamp unit 20 and is fixed to the lamp body 14. The first lamp unit 18 is disposed outside the second lamp unit 20 in the vehicle width direction of the vehicle. The first lamp unit 18 is a so-called parabolic lamp unit, and forms a low beam light distribution pattern to be described later.

  The first lamp unit 18 includes a reflector 22, a light source bulb 24, and a shade 26. The reflector 22 is formed in a cup shape, and an insertion hole is provided in the center. In the present embodiment, the light source bulb 24 is configured by an incandescent lamp having a filament such as a halogen lamp. The light source bulb 24 may employ other types of light sources such as a discharge lamp. The light source bulb 24 is inserted into the insertion hole of the reflector 22 so as to protrude inside, and is fixed to the reflector 22. The reflector 22 has a curved inner surface so as to reflect the light emitted from the light source bulb 24 toward the front of the vehicle. The shade 26 blocks light that travels directly from the light source bulb 24 toward the front of the vehicle. Since the structure of the 1st lamp unit 18 is well-known, the detailed description regarding the 1st lamp unit 18 is abbreviate | omitted. In addition, you may use the below-mentioned light emitting module as a light source of the 1st lamp unit 18. FIG.

  FIG. 2 is a diagram showing a configuration of the second lamp unit 20 included in the lamp body unit 10 of the present embodiment. FIG. 2 shows a cross-sectional view of the second lamp unit 20 cut from a horizontal plane and viewed from above. The second lamp unit 20 includes a holder 28, a projection lens 30, a light emitting module 32, and a heat sink 38. The 2nd lamp unit 20 is a lamp unit which irradiates the light which can form all or one part area | regions of the high beam light distribution pattern. That is, the second lamp unit 20 forms the high beam light distribution pattern on the low beam light distribution pattern formed by the first lamp unit 18 in the high beam irradiation mode. By adding the high-beam light distribution pattern to the low-beam light distribution pattern, the irradiation range is widened as a whole, and the distance viewing performance is improved. Further, the second lamp unit 20 irradiates light alone in the daytime lighting irradiation mode, so that it is easy to recognize the presence of the vehicle by an oncoming vehicle or a pedestrian during daytime, so-called daylighting lamp. It functions as a time running lamp (DRL).

  The projection lens 30 is a plano-convex aspheric lens having a convex front surface and a flat rear surface, and projects a light source image formed on the rear focal plane onto a virtual vertical screen in front of the lamp as a reverse image. To do. The projection lens 30 is attached to one opening of a holder 28 formed in a cylindrical shape. The light emitting module 32 corresponds to the light emitting modules according to the following embodiments and examples.

[Light emitting module]
Next, the configuration of the light emitting module according to the present embodiment will be described in detail. The light emitting module according to the present embodiment includes a semiconductor light emitting element and a mounting substrate on which the semiconductor light emitting element is mounted. In the mounting substrate, a reflective film that reflects light emitted from the semiconductor light emitting element is formed on the side on which the semiconductor light emitting element is mounted. The reflective film is entirely made of an insulating inorganic material. A copper wiring pattern is formed on the reflective film. A part of the wiring pattern functions as an electrode, and the electrode and the semiconductor light emitting element are connected by a bump or a bonding wire.

  In addition, a phosphor layer is provided around the semiconductor light emitting element or on the emission surface, and is excited by light emitted from the semiconductor light emitting element to emit visible light. The light emitting module configured as described above irradiates, for example, white light forward by mixing light emitted from the semiconductor light emitting element and light from the phosphor layer excited by the light.

  Next, each member constituting the light emitting module will be described in detail.

[Mounting board]
The mounting substrate according to the present embodiment is not limited to a specific type or material as long as electrical wiring can be provided on the surface, upper part, or inside thereof. For example, a resin substrate, a resin composite substrate, an oxide ceramic substrate, a nitride ceramic substrate, a carbide ceramic substrate, a silicide ceramic substrate, a boride ceramic substrate, a metal substrate, or a combination of these materials Can be employed as a mounting substrate.

  As resin substrates, epoxy resin, phenol resin, acrylic resin, polyethylene terephthalate, polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aramid, polycarbonate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, natural rubber And a substrate made of a material such as.

  Examples of the resin composite substrate include a paper phenol substrate in which paper is impregnated with phenol resin or epoxy resin, a paper epoxy substrate, a substrate in which glass cloth, carbon fiber cloth, or the like is impregnated with epoxy resin or the like.

Examples of oxide ceramic substrates include glass, quartz, alumina, titania, zirconia, zinc oxide, bismuth oxide, germanium oxide, lead oxide, lead dioxide, tantalum pentoxide, calcium titanate, barium titanate, lead titanate, PZT. , PLZT, magnesium oxide, YAG (yttrium aluminum garnet), ThO ₂ , BeO, Cr ₂ O ₃ , and the like.

Examples of the nitride-based ceramic substrate include substrates made of materials such as tantalum nitride, zirconium nitride, titanium nitride, silicon nitride, aluminum nitride, HfN, Si ₃ N ₄ , and SiAlON. Examples of the carbide-based ceramic substrate include substrates made of materials such as silicon carbide, Cr ₃ C ₂ , TiC, NbC, ZrC, HfC, TaC, B ₄ C, and WC. In addition, examples of the silicide ceramic substrate include a substrate made of a material such as MoSi ₂ , WSi ₂ , SiB ₆ .

As the boride-based ceramic substrate, TaB ₂ , NbB ₂ , TiB ₂ , UB ₂ , ZrB ₂ , ThB ₆ , HfB ₂ , UB ₄ , VB ₂ , CaB ₆ , SrB ₆ , BaB ₆ , ThB ₄ , WB, etc. And a substrate made of the above material. In addition, examples of the metal substrate include metal substrates such as iron, copper, aluminum, and stainless steel, or a substrate in which the above materials are combined.

  When the light-emitting module according to this embodiment is manufactured using a mounting substrate selected from the above various substrates, a thin resin substrate (film substrate), ceramic substrate, or metal substrate is preferable from the viewpoint of heat dissipation. In terms of insulation, a ceramic substrate is particularly preferable.

  The mounting substrate described above may have a roughened surface in order to diffusely reflect the light emitted from the semiconductor light emitting element or the phosphor layer, or to improve adhesion. The surface of the mounting substrate is roughened by, for example, mechanical polishing, grinding, or etching. For mechanical polishing and grinding, for example, sandblasting, abrasive grains, files, drills, and the like are used. Examples of the etching include plasma etching such as oxygen, nitrogen, argon, and chlorine, etching using chemicals including alkali such as sodium hydroxide and potassium hydroxide, and acids such as hydrochloric acid, sulfuric acid, and chromic acid.

  On the surface of these mounting substrates, members and layers such as electrodes, insulating films, solder resists, etching resists, underfills, reflectors, and solder pastes are formed in a single layer and / or multiple layers.

[Insulating layer (reflective film)]
The reflective layer according to the present embodiment is preferably one that is electrically insulating and can be provided with electric wiring on the surface thereof. In particular, the entire reflective layer is preferably an insulating inorganic material. Examples of the inorganic material include oxide ceramics, nitride ceramics, carbide ceramics, silicide ceramics, boride ceramics, and composite materials obtained by combining these materials.

Examples of oxide ceramics include glass, quartz, alumina, titania, zirconia, zinc oxide, bismuth oxide, germanium oxide, lead oxide, lead dioxide, tantalum pentoxide, calcium titanate, barium titanate, lead titanate, PZT, PLZT. , magnesium oxide, YAG (yttrium aluminum _{garnet), ThO 2, BeO, Cr} 2 O 3, include materials etc. it is.

Examples of the nitride ceramic include materials such as tantalum nitride, zirconium nitride, silicon nitride, aluminum nitride, HfN, Si ₃ N ₄ , and SiAlON. Examples of the carbide-based ceramic include silicon carbide, Cr ₃ C ₂ , NbC, ZrC, HfC, TaC, and B ₄ C. Examples of silicide ceramics include MoSi ₂ , WSi ₂ , SiB ₆ , and the like.

Examples of boride-based ceramics include TaB ₂ , NbB ₂ , TiB ₂ , UB ₂ , ZrB ₂ , ThB ₆ , HfB ₂ , UB ₄ , VB ₂ , CaB ₆ , SrB ₆ , BaB ₆ , ThB ₄ , WB, and the like. Materials.

  Then, an insulating reflective film made of an inorganic material is formed by depositing these substances on the surface of the mounting substrate in a single layer and / or multiple layers. Note that the reflective film is not limited to being made entirely of an inorganic material, but may be a case where an impurity mixed in a raw material manufacturing or film forming process is contained in the inorganic material. In addition, an electrically conductive film or an electronic component may be provided inside as long as the reflective film as a whole can satisfy insulating properties. A reflective film that is an insulator can be formed on the surface of the mounting substrate by bonding such a sheet-like or film-like reflective film made of an inorganic material to the mounting substrate by thermal lamination or lamination using an adhesive.

  These insulating materials can be dissolved in an appropriate solvent such as water and ketones, or an insulating reflective film can be formed on the substrate surface by a method of applying to the substrate while melting by heating. Such film forming methods include roll applicator, liquid reservoir applicator, immersion applicator, fountain applicator, extrusion applicator, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater Examples thereof include a roll coater, a gravure coater, a kiss roll coater, a cast coater, a spray coater, a curtain coater, a calendar coater, an extrusion coater, an electrostatic coater, a spray coater, a slot orifice coater, and an electrodeposition coater.

  Also, vacuum deposition, thermal evaporation, sputtering, ion plating, plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), aerosol deposition (AD), plasma ion assist (PIA), Etc. can also be used to form an insulating reflective film on the substrate surface.

  The reflective film preferably has a refractive index of 1.4 or more at sodium D-line (wavelength 589 nm) from the viewpoint of reflecting visible light. When the refractive index is low, light traveling from the semiconductor light emitting element or the fluorescent layer to the mounting substrate passes through the insulating layer (reflection film) or the mounting substrate and is lost. On the other hand, when the refractive index of the reflective film is 1.4 or more, the light traveling from the semiconductor light emitting element to the mounting substrate is easily reflected by the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved.

  The reflective film is preferably roughened so that the surface roughness Ra on the side facing the semiconductor light emitting element is in the range of about 0.1 μm to about 80 μm. For the roughening, the surface of the reflective film may be directly roughened, or the surface of the reflective film provided thereon may be indirectly roughened by roughening the underlying mounting substrate.

  When the surface roughness Ra is smaller than 0.1 μm, the light from the semiconductor light emitting element is hardly diffusely reflected, and passes through the reflection film or the mounting substrate as it is and is lost. On the other hand, when the surface roughness Ra is larger than 80 μm, it is difficult to form an electrical wiring on the surface of the reflective film, and even if the electrical wiring can be formed, it is easily peeled off. On the other hand, when the surface roughness Ra of the reflective film is about 0.1 μm to about 80 μm, light traveling from the semiconductor light emitting element to the mounting substrate is irregularly reflected on the surface of the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved.

  The roughening of the surface of the formed reflective film is performed by, for example, mechanical polishing, grinding, or etching. For mechanical polishing and grinding, sandblasting, abrasive grains, files, drills and the like are used. Examples of the etching include plasma etching such as oxygen, nitrogen, argon, and chlorine, etching using chemicals including alkali such as sodium hydroxide and potassium hydroxide, and acids such as hydrochloric acid, sulfuric acid, and chromic acid.

The reflective film is preferably a multilayer film of a high refractive index film and a low refractive index film each having a layer thickness of about ¼ wavelength of the light of the semiconductor light emitting element from the viewpoint of reflection of visible light. Examples of the low refractive index film include calcium fluoride, cryolite (Na ₃ AlF ₆ ), lanthanum fluoride, lithium fluoride, magnesium fluoride, thorium fluoride, and the like, silicon trioxide, and silicon dioxide.

  High refractive index films to be combined include antimony trioxide, beryllium oxide, bismuth trifluoride, cerium oxide, hafnium dioxide, lanthanum oxide, lead chloride, lead fluoride, magnesium oxide, neodymium oxide, praseodymium oxide, tantalum pentoxide, Examples thereof include titanium dioxide, thallium chloride, thorium oxide, yttrium oxide, zinc sulfide, and zirconium dioxide.

[Underfill]
The light-transmitting underfill is not limited to a specific type or material as long as it has a light-transmitting property by penetrating into the gap between the semiconductor light emitting element and the mounting substrate. In the case of a light emitting module without an underfill, light is not easily emitted to the outside at the interface with the air of the semiconductor light emitting element, so that a part of the light generated in the semiconductor light emitting element disappeared as heat while being confined inside. However, since the refractive index of the underfill is higher than that of air, the underfill covers the surface of the semiconductor light emitting element on the mounting substrate side, so that light is easily emitted from the semiconductor light emitting element.

  Underfill includes epoxy resin, acrylic resin, silicone resin, silica-based sol / gel material, titania-based sol / gel material, polystyrene, polyacrylonitrile, polytetrafluoroethylene, TPX, vinyl chloride, polycarbonate, nylon, polyester, poly Examples include sulfone, polyimide, polypropylene, polyethylene, polycycloolefin, and silsesquioxane. In particular, a silicone resin, a silica-based sol / gel material, a titania-based sol / gel material, and silsesquioxane having excellent photodegradability are suitable as the underfill.

[Semiconductor light emitting device]
The semiconductor light emitting device according to the present embodiment may emit light in any wavelength range such as visible light emission, ultraviolet light emission, infrared light emission. Examples of the semiconductor light emitting element include an LED and an LD. The LED is manufactured, for example, by crystal growth on a sapphire substrate in the order of n-GaN / InGaN active layer / p-GaN and producing electrode pads on the n-GaN layer and the p-GaN layer, respectively.

[Phosphor layer]
Examples of the phosphor layer according to the present embodiment include a resin composition, a glass composition, and a fluorescent ceramic in which a powdered phosphor is dispersed. As the phosphor, YAG (Yttrium Aluminum Garnet) powder excited by blue light can be used. The phosphor is not limited to a phosphor excited by blue light, and may be a phosphor excited by near ultraviolet light or ultraviolet light, for example.

  The thickness of the phosphor layer may be appropriately set in consideration of the color and brightness of light required for the light emitting module, the type of semiconductor light emitting element (for example, LED chip) to be combined, and the like. For example, if the thickness is 1 μm or more, the light emitted from the LED chip can be sufficiently wavelength-converted. Moreover, if thickness is 1000 micrometers or less, the light of an LED chip can fully be permeate | transmitted.

  Hereinafter, the luminance of the light emitting module in which the above-described various configurations are combined will be described with reference to each example and each comparative example. FIG. 3 is a table in which the configurations and luminances of the light emitting modules according to the examples and the comparative examples are summarized in a table. In addition, the optical characteristic of the unit of the light emitting module produced in each following Example was shown by the relative value by making the value of the light emitting unit produced in Comparative Example 1-1 into 100. In an automotive lamp, it is necessary to illuminate 100m to 200m ahead, and it is preferable that both luminance and luminous flux are higher than those of the comparative example.

  The optical characteristics were measured by attaching the light emitting module to an aluminum die cast heat sink, driving at a constant current of 700 mA, and lighting for 10 minutes until stabilized. Thereafter, the luminance of the upper surface of the light emitting module was measured using a spectroradiometer SR-3 manufactured by Topcon Corporation. The total luminous flux was measured using a spectrophotometer MCPD-1000 manufactured by Otsuka Electronics Co., Ltd. with a 700 mA current flowing in a integrating sphere of φ150 for 10 milliseconds.

  The reliability was defined as the time required for the total luminous flux to fall to 70% of the initial value when the LED package was continuously lit. As reliability sufficient for an automotive lamp, it is preferably 3000 hours or more. 3000 hours corresponds to 10 years when converted into actual use of a car.

(Example 1-1, Comparative example 1-1, Comparative example 1-2)
FIG. 4 is a cross-sectional view schematically showing a main part of the light emitting module according to Example 1-1. The light emitting module 40 shown in FIG. 4 is provided so as to cover the LED chip 42 as a semiconductor light emitting element, the LED chip 42, and a phosphor layer 44 that converts light emitted from the LED chip 42, and the LED chip 42. A mounting substrate 46 and a wiring layer 48 are provided. The reflective film 50 described above is formed on the surface of the mounting substrate 46 on which the LED chip 42 is mounted.

  A part of the wiring layer 48 formed on the surface of the reflective film 50 is processed as electrodes 52 and 54. The electrode 52 is electrically connected to the bottom surface of the LED chip 42, and the electrode 54 is electrically connected to the electrode on the upper surface of the LED chip 42 by a gold wire 56. The LED chip 42 is a so-called vertical (VC) type LED.

  In the light emitting module 40 according to Example 1-1, a silica film is formed as an insulating reflective film 50 on an aluminum mounting substrate 46. The silica film is formed by a CVD (chemical vapor deposition) method using tetraethoxysilane as a raw material. Copper wiring is applied on the silica film. The LED chip 42 is a blue LED having a light emission wavelength center at 450 nm and a size of 1 × 1 mm, and is fixed to the electrode 52 with a silver paste with the conductive substrate facing down. The LED chip 42 is covered with a paste-like phosphor layer 44 obtained by kneading YAG (yttrium aluminum garnet) phosphor powder in dimethyl silicone resin. The thickness of the phosphor layer 44 is 200 μm. The phosphor layer 44 covers the periphery of the LED chip 42 so that the projected area when viewed from the direction A shown in FIG. 4 is about 1.2 times the area of the LED chip 42. In the light emitting module according to Example 1-1, the reliability reached 3000 hours.

  On the other hand, in Comparative Example 1-1, a polyimide resin (Toray Industries, Inc. Semicofine SP-300) was applied as an insulating film on an aluminum substrate, and copper wiring was applied thereon to produce a mounting substrate. Using this mounting substrate, a light emitting module having the same configuration as that of Example 1-1 was manufactured. In the light emitting module according to Comparative Example 1-1, the reliability was 1000 hours.

  On the other hand, in Comparative Example 1-2, a white solder resist (PSR-4000 manufactured by Taiyo Ink Manufacturing Co., Ltd.) was applied as an insulating film on an aluminum substrate, and copper wiring was applied thereon to produce a mounting substrate. Using this mounting substrate, a light emitting module having the same configuration as that of Example 1-1 was manufactured. In the light emitting module according to Comparative Example 1-2, the reliability was 100 hours.

  As described above, in the light emitting module 40 according to Example 1-1, the light emitted from the LED chip 42 toward the mounting substrate 46 is reflected by the reflective film 50 and irradiated in a predetermined irradiation direction. Therefore, the light use efficiency can be improved. Moreover, since the reflection film 50 is entirely made of an insulating inorganic material, deterioration due to light emitted from the LED chip 42 is suppressed. Even if the light emitted from the LED chip 42 is ultraviolet light or short-wavelength visible light, the reflection film 50 is mainly composed of an inorganic material, so that the reflection film is deteriorated as compared with the case where the reflection film contains a large amount of resin components. It is suppressed and the reliability of the light emitting module is improved. Further, as is clear from the evaluation results of the light emitting module according to Example 1-1, the reliability was significantly improved by using inorganic silica for the reflective film (insulating film).

(Examples 2-1 to 2-4, Comparative examples 2-1 to 2-3)
The light emitting modules according to Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 are different from the light emitting modules according to Example 1-1 in that the surface roughness of the reflective film is different. Is a big difference in configuration. The light emitting module according to Comparative Example 2-1 has a reflective film with a refractive index different from that of other light emitting modules.

  In the mounting substrates of Example 2-1 and Example 2-2, the surface of the aluminum nitride substrate was adjusted by the sandblasting method so that the surface roughness Ra was 0.1 and 10 μm, respectively, and reflected on the surface. As a film, a silica film is formed by a CVD (chemical vapor deposition) method using tetraethoxysilane as a raw material. And the light emitting module of the structure similar to Example 1-1 was produced using the mounting substrate which confirmed that the surface roughness of the reflecting film was 0.1 and 10 micrometers.

  In the mounting substrates of Example 2-3 and Example 2-4, the surface of the aluminum nitride substrate was adjusted by the sand blasting method so that the surface roughness Ra was 0.1 and 10 μm, respectively, and reflected on the surface. As the film, a titanium oxide film is formed by a CVD (chemical vapor deposition) method using tetraisopropoxy titanium as a raw material. And the light emitting module of the structure similar to Example 1-1 was produced using the mounting substrate which confirmed that the surface roughness of the reflecting film was 0.1 and 10 micrometers.

  In the mounting substrate of Comparative Example 2-1, the surface of the aluminum nitride substrate is adjusted by a sandblast method so that the surface roughness Ra is 0.1 μm, and magnesium fluoride is sputtered as a reflective film thereon. Is used to form a film. And the light emitting module of the structure similar to Example 1-1 was produced using the mounting substrate which confirmed that the surface roughness of the reflecting film was 0.1 micrometer.

  In the mounting substrates of Comparative Example 2-2 and Comparative Example 2-3, the surface of the aluminum nitride substrate is made to have a surface roughness Ra of 0.05 and 100 μm, respectively, by a sandblast method, and a reflective film is formed thereon. As described above, a silica film is formed by a CVD (chemical vapor deposition) method using tetraethoxysilane as a raw material. And the light emitting module of the structure similar to Example 1-1 was produced using the mounting substrate which confirmed that the surface roughness of the reflecting film was 0.05 and 100 micrometers.

  In the light emitting module of Comparative Example 2-1, since the reflective film was magnesium fluoride (refractive index 1.38), the light from the LED chip toward the mounting substrate could not be sufficiently reflected. On the other hand, in the light emitting module according to Example 2-1, since the reflection film is silica (refractive index 1.45), the light from the LED chip 42 toward the mounting substrate is sufficiently reflected, and the luminance and the total luminous flux are improved.

  Comparison between Comparative Example 2-2 and Example 2-1 suggests that surface roughness is important. That is, in the insulating film transparent to visible light, the unevenness having a wavelength equal to or less than ¼ wavelength of the light of the LED chip does not diffusely reflect and transmits to the lower side of the aluminum nitride substrate, so that neither luminance nor total luminous flux is improved. However, in the light emitting modules according to Example 2-1 and Example 2-2, the visible light was irregularly reflected on the surface of the reflective film, so both the luminance and the total luminous flux were improved.

  On the other hand, in the light emitting module according to Comparative Example 2-3, since the surface roughness was too large, the LED chip was peeled after the LED chip was mounted on the mounting substrate.

(Example 3-1 and Example 3-2)
In the mounting substrate according to Example 3-1, silica (refractive index of 1.45) and titanium oxide (refractive index of about 2) having a thickness of about ¼ wavelength of the light of the LED chip as a reflective film on the surface of the aluminum substrate, respectively. A multilayer film in which .2 to 2.3) are alternately laminated is formed. Using this mounting substrate, a light emitting module having the same configuration as that of Example 1-1 was manufactured.

  In the mounting substrate according to Example 3-2, the surface of the aluminum substrate is adjusted by the sandblast method so that the surface roughness Ra becomes 10 μm, and a reflective film is formed on the surface of the aluminum substrate as a quarter of the light of the LED chip. A multilayer film in which silica and titanium oxide having a thickness of about a wavelength are alternately laminated is formed. Using this mounting substrate, a light emitting module having the same configuration as that of Example 1-1 was manufactured.

  As described above, in the reflective film of Example 3-1, the first inorganic material having a refractive index of 1.4 or more and the second inorganic material having a refractive index higher than that of the first inorganic material are alternately stacked. A multilayer film. Therefore, the light traveling from the LED chip toward the mounting substrate is more easily reflected by the reflective film. Since the reflected light is emitted from the emission surface of the semiconductor light emitting device, the light utilization efficiency is improved. In addition, by setting the thickness of each layer of the reflective film, which is a multilayer film, as described above, the reflection efficiency can be increased, and the light utilization efficiency of the light emitting module can be dramatically increased.

  As described above, in the light emitting module according to Example 3-1, since the reflection film itself reflects visible light, the luminance and the total luminous flux are significantly increased even when the surface is smooth. Further, as in the light emitting module according to Example 3-2, when the surface was roughened, the luminance and the total luminous flux were further increased.

(Example 4-1 and Comparative example 4-1)
FIG. 5 is a cross-sectional view schematically illustrating the main part of the light emitting module according to Example 4-1. The description of the same configuration and operation as those of the light emitting module according to Example 1-1 illustrated in FIG. 4 will be omitted as appropriate. The light emitting module 60 shown in FIG. 5 includes a so-called flip chip (FC) type LED chip 62, an aluminum nitride mounting substrate 64, a copper wiring layer 66, and electrode portions of the LED chip 62 and the copper wiring layer 66. And a phosphor layer 70 that converts light emitted from the LED chip 62. The reflection film 72 described above is formed on the surface of the mounting substrate 64 on the side where the LED chip 62 is mounted.

  In the light emitting module 60 according to Example 4-1, a reflective film similar to the multilayer film of Example 3-1 is formed on a mounting substrate 64 made of aluminum nitride. A copper wiring layer 66 is formed on the multilayer film. The LED chip 62 is a blue LED having a light emission wavelength center at 450 nm and a size of 1 × 1 mm, and is fixed to the mounting substrate with the sapphire substrate facing up. The LED chip 62 and the mounting substrate 64 are electrically connected to each other via gold balls 68 and are fixed to each other. The upper surface of the LED chip 42 is covered with a paste-like phosphor layer 70 obtained by kneading YAG (yttrium aluminum garnet) phosphor powder in dimethyl silicone resin. The thickness of the phosphor layer 44 is 200 μm. The phosphor layer 70 is processed so that the projected area when viewed from the B direction shown in FIG. 5 is the same area as the LED chip 42.

  The light emitting module according to Comparative Example 4-1 has the same configuration as that of the light emitting module 60 according to Example 4-1, except that the reflective film is not formed.

  Since the light emitting module according to Example 4-1 has a flip chip structure, there is no electrode on the upper surface of the LED chip 62, and all the electrodes exist on the mounting substrate side, so that the area covered with the phosphor layer 70 can be reduced, High brightness can be achieved. For example, as shown in FIG. 3, the luminance is increased to about 1.5 times the luminance of the light emitting module according to Example 3-1.

  In addition, the LED chip 62 flip-chip connected to the mounting substrate 64 is provided with gold balls 68 between the mounting substrate 64. Therefore, part of the light generated by the LED chip 62 is likely to be emitted from the gap between the gold balls 68 toward the mounting substrate 64. Therefore, by forming the above-described reflective film 72 on the mounting substrate 64, the light directed toward the mounting substrate 64 is reflected again toward the LED chip 62 and irradiated forward from the emission surface 62 a of the LED chip 62. Therefore, in the case of such a configuration, the effect of improving the utilization efficiency of light emitted from the LED chip 62 becomes more remarkable.

(Example 5-1)
FIG. 6 is a cross-sectional view schematically showing the main part of the light emitting module according to Example 5-1. The description of the same configuration and operation as those of the light emitting module according to Example 4-1 illustrated in FIG. In the light emitting module 80 according to Example 5-1, a transparent dimethyl silicone resin was poured as an underfill 82 into the space between the LED chip 62 and the reflective film 72 and heated at 150 ° C. for 1 hour to heat the dimethyl silicone resin. Cured.

  Since the light emitting module according to Example 5-1 has a flip chip structure, there is no electrode on the upper surface of the LED chip 62, and all the electrodes exist on the mounting substrate side, so that the area covered with the phosphor layer 70 can be reduced, High brightness can be achieved. In addition, light that leaks out to the lower side of the LED chip 62 can be efficiently extracted toward the mounting substrate side by the action of the translucent underfill 82. Therefore, the luminance and total luminous flux are reflected by reflecting the light on the reflective film. Can be improved.

(Example 6-1)
FIG. 7 is a cross-sectional view schematically showing a main part of the light emitting module according to Example 6-1. The description of the same configuration and operation as those of the light emitting module according to Example 4-1 illustrated in FIG. In the light emitting module 90 according to Example 6-1, a part of the aluminum nitride mounting substrate 92 is processed into a concave shape, and a reflective film 94 is formed on the mounting substrate 92 along the shape. The LED chip 62 is mounted on the portion processed into the concave shape. The reflective film 94 is the multilayer film described in Example 3-1.

  In the light emitting module 90 according to Example 6-1, the light leaking from the side surface of the LED chip 62 is reflected by the reflective film 94a formed on the concave slope of the mounting substrate 92 so that the light is directed upward. The luminous flux can be improved. Therefore, the light emitting module 90 is particularly suitable for vehicle lamps and lighting equipment.

(Example 7-1)
FIG. 8 is a cross-sectional view schematically showing a main part of the light emitting module according to Example 7-1. The description of the same configuration and operation as those of the light emitting module according to Example 6-1 shown in FIG. In the light emitting module 100 according to Example 7-1, four recesses 104 are formed in an aluminum nitride mounting substrate 102, and a reflective film 106 is formed on the mounting substrate 102 along the shape. The LED chip 62 is mounted in each recess 104. The reflective film 106 is the multilayer film described in Example 3-1.

  In the light emitting module 100 according to Example 7-1, the light leaking from the side surface of the LED chip 62 is also reflected by the reflective film 106a formed on the slope of the concave portion 104 of the mounting substrate 102, so that the light is directed upward. , The total luminous flux can be improved. Further, the copper wiring layer 108 has a wiring pattern capable of individually dimming the LED chip 62. Therefore, the light emitting module 100 is particularly suitable for a vehicular lamp that can change the light distribution and a lighting device that can adjust the brightness.

  FIG. 9 is a cross-sectional view of a lighting fixture that can employ the light emitting module according to the present embodiment. The lighting fixture 110 includes a light emitting module 112, a heat dissipation substrate 114, a front cover 116, a housing 118, a control circuit unit 120, and a mounting member 122. The light emitting module 112 can take various configurations described in the above embodiments and examples. The heat dissipation board 114 is made of a material having high heat dissipation properties such as metal, and plays a role of absorbing heat generated by the light emitting module 112 and dissipating heat to the outside. The front cover 116 is provided so as to cover the light emitting module 112 and protects the light emitting module 112. The front cover 116 is made of a transparent or translucent material so that light from the light emitting module 112 can be transmitted forward or diffused.

  The casing 118 is mainly made of a resin material and houses the control circuit unit 120. The control circuit unit 120 controls lighting of the light emitting module 112. The attachment member 122 fixes the control circuit unit 120 to the heat dissipation board 114 and the housing 118.

  In the above, this invention was demonstrated based on each embodiment and each Example. Those skilled in the art will understand that these embodiments and examples are merely examples, and various modifications can be made to the combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. It is where it is done.

  10 lamp body unit, 40 light emitting module, 42 LED chip, 44 phosphor layer, 46 mounting substrate, 48 wiring layer, 50 reflective film, 52,54 electrode, 56 gold wire, 62 LED chip, 62a emitting surface.

Claims (3)

A semiconductor light emitting device;
A mounting substrate on which the semiconductor light emitting element is mounted;
The mounting substrate has a reflective film that reflects light emitted from the semiconductor light emitting element on the side on which the semiconductor light emitting element is mounted,
The reflective film is entirely made of an insulating inorganic material,
The reflective film is Ri multilayer der the first inorganic material having a refractive index of more than 1.4, and the higher refractive index than the first inorganic material second inorganic material is at least stacked,
Light emitting module and further comprising said Rukoto a light-transmitting underfill is filled between the reflection film and the semiconductor light emitting element.   2. The light emitting module according to claim 1, wherein the reflective film has a surface roughness Ra on the side facing the semiconductor light emitting element of 0.1 μm to 80 μm.   The light emitting module according to claim 1, wherein the semiconductor light emitting element is flip-chip connected to the mounting substrate.

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