WO2014104035A1

WO2014104035A1 - Reflective substrate

Info

Publication number: WO2014104035A1
Application number: PCT/JP2013/084533
Authority: WO
Inventors: 優介畠中
Original assignee: 富士フイルム株式会社
Priority date: 2012-12-27
Filing date: 2013-12-24
Publication date: 2014-07-03

Abstract

The purpose of the present invention is to provide a reflective substrate which has excellent heat dissipation properties, while exhibiting excellent adhesion to an inorganic reflective layer. A reflective substrate of the present invention comprises a metal base and an inorganic reflective layer that is provided on at least a part of the surface of the metal base. The metal base contains at least one metal that is selected from the group consisting of gold, silver and copper. The inorganic reflective layer contains inorganic particles and an inorganic binder that contains phosphoric acid and/or a metal phosphate.

Description

Reflective substrate

The present invention relates to a reflective substrate, and more specifically to a reflective substrate used for mounting a light emitting element such as a light emitting diode (hereinafter referred to as “LED”).

In general, LEDs are said to have a power consumption of 1/100 and a lifespan of 40 times (40000 hours) compared to fluorescent lamps. Such a feature of power saving and long life is an important factor in adopting LEDs in an environment-oriented flow.
In particular, white LEDs are excellent in color rendering properties and have a merit that a power supply circuit is simpler than fluorescent lamps, and therefore, expectations for light sources for illumination are increasing.
In recent years, white LEDs (30 to 150 Lm / W) with high luminous efficiency, which are required as illumination light sources, have appeared one after another, and in terms of light use efficiency in practical use, the fluorescent lamps (20 to 110 Lm / W) have been reversed. is doing.
As a result, the flow of practical use of white LEDs instead of fluorescent lamps has increased rapidly, and the number of cases in which white LEDs are employed as backlights or illumination light sources for liquid crystal display devices is increasing.

As a substrate that can be used for such a white LED, Patent Document 1 discloses that “an inorganic reflective layer is provided on at least a part of a valve metal substrate, and the inorganic reflective layer is made of aluminum phosphate, aluminum chloride, and sodium silicate. For light-emitting elements, comprising at least one inorganic binder selected from the group consisting of and inorganic particles having a refractive index of 1.5 to 1.8 and an average particle size of 0.1 to 5 μm Reflective substrate "is described.

International Publication No. 2012/133173

As a result of studying the reflective substrate for a light emitting element described in Patent Document 1, the present inventor has sufficiently secured the adhesion (adhesion) between the valve metal substrate and the inorganic reflective layer. It has been clarified that there is room for improvement in the property (thermal conductivity).
And when this inventor employ | adopted the metal (gold, silver, or copper) with high heat conductivity as a metal base material, although heat dissipation became favorable, depending on the inorganic binder to be used, an inorganic reflective layer and It has been clarified that the adhesion to the metal substrate may be inferior.

Therefore, an object of the present invention is to provide a reflective substrate that is excellent in heat dissipation and adhesiveness with an inorganic reflective layer.

As a result of earnest research to achieve the above object, the inventor of the present invention provides a metal having high thermal conductivity by providing an inorganic reflective layer containing a specific inorganic binder containing a metal phosphate or the like together with inorganic particles. The inventors have found that the adhesiveness is excellent also with respect to the substrate, and completed the present invention.
That is, the present invention provides a reflective substrate having the following configuration.

(1) having a metal substrate and an inorganic reflective layer provided on at least a part of the surface of the metal substrate;
The metal substrate is composed of at least one metal selected from the group consisting of gold, silver and copper;
A reflective substrate, wherein the inorganic reflective layer contains an inorganic binder containing phosphoric acid and / or a metal phosphate and inorganic particles.
(2) The reflective substrate according to (1), wherein the metal phosphate is at least one selected from the group consisting of gold phosphate, silver phosphate, and copper phosphate.
(3) The reflective substrate according to (1) or (2), wherein the metal constituting the metal substrate and the metal constituting the metal phosphate are the same type of metal.
(4) The reflective substrate according to any one of (1) to (3), wherein the refractive index of the inorganic particles is from 1.5 to 1.8, and the average particle diameter is from 0.1 μm to 5 μm.
(5) The reflective substrate according to any one of (1) to (4), wherein the inorganic particles are at least one selected from the group consisting of oxides, hydroxides, and inorganic salts.
(6) The reflective substrate according to any one of (1) to (5), wherein the inorganic particles are at least one selected from the group consisting of aluminum oxide, calcium hydroxide, and barium sulfate.
(7) The reflective substrate according to any one of (1) to (6), wherein the metal substrate has a thickness of 0.1 to 3 mm.
(8) The reflective substrate according to any one of (1) to (7), wherein the arithmetic average roughness Ra of the surface is 0.50 to 1.00 μm and the average interval Psm of the unevenness is 10 to 20 μm.
(9) An LED package comprising the reflective substrate according to any one of (1) to (8) and an LED light emitting element mounted on the surface.

According to the present invention, it is possible to provide a reflective substrate that is excellent in heat dissipation and adhesiveness with an inorganic reflective layer.

It is typical sectional drawing which shows an example of suitable embodiment of the reflective substrate of this invention. It is typical sectional drawing which shows an example of the suitable embodiment of the LED package of this invention. It is the schematic explaining the wiring pattern used for evaluation.

[Reflective substrate]
Hereinafter, the reflective substrate of the present invention will be described in detail.
The reflective substrate of the present invention has a metal base material and an inorganic reflective layer provided on at least a part of the surface of the metal base material, and the metal base material is selected from the group consisting of gold, silver and copper. A reflective substrate suitably used for mounting a light emitting device, comprising at least one metal, and wherein the inorganic reflective layer contains an inorganic binder containing phosphoric acid and / or a metal phosphate and inorganic particles. .
Next, the configuration of the reflective substrate of the present invention will be described with reference to FIG.

FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the reflective substrate of the present invention.
As shown in FIG. 1, the reflective substrate 1 of the present invention has a metal base 2 and an inorganic reflective layer 3 provided on at least a part of the surface of the metal base 2, and the inorganic reflective layer 3 is inorganic. A reflective substrate containing particles 4 and an inorganic binder 5.

[Metal base material]
The metal substrate used for the reflective substrate of the present invention is not particularly limited as long as it is composed of at least one metal selected from the group consisting of gold, silver, and copper.
Here, “consisting of metal” means not only a metal substrate composed of only the above metal but also a metal substrate composed of an alloy of these metals (for example, an alloy of copper and silver). Is included.
By using a metal substrate composed of such a metal, the heat dissipation of the reflective substrate of the present invention is improved.
Of these, copper is preferable from the viewpoints of easy workability and high weather resistance.

In the present invention, the thickness of the metal substrate is preferably 0.1 to 3 mm, more preferably 0.15 to 1.5 mm, for the reason that heat dissipation is better. More preferably, it is 1.0 mm. This thickness can be appropriately changed according to the user's wishes or the like.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Inorganic reflective layer]
The inorganic reflective layer included in the reflective substrate of the present invention is a reflective layer containing an inorganic binder containing phosphoric acid and / or a metal phosphate and inorganic particles.
Hereinafter, the inorganic binder and the inorganic particles contained in the inorganic reflective layer will be described in detail.

<Inorganic binder>
The inorganic binder contained in the inorganic reflective layer is not particularly limited as long as it contains at least phosphoric acid and / or a metal phosphate.
By using such an inorganic binder, the adhesiveness between the inorganic reflective layer and the metal substrate is improved.
This is because the inorganic binder binds inorganic particles to be described later, and also enters the gap between the metal substrate and the inorganic particles, and reacts with the metal substrate when forming the inorganic reflective layer. It is thought that a network of phosphate bonds is formed also at the interface, and a stronger bond is expressed.

In the present invention, the inorganic binder preferably contains 50% by mass or more of phosphoric acid and / or metal phosphate, more preferably 80% by mass or more, and 100% by mass, that is, the inorganic binder. It is more preferable to use only phosphoric acid and / or metal phosphate.

(Metal phosphate)
The phosphoric acid metal salt is not particularly limited, and examples of the phosphoric acid in the phosphoric acid metal salt include phosphoric acid, metaphosphoric acid, orthophosphoric acid, polyphosphoric acid, sesquiphosphoric acid, and the like. As the metal in the phosphoric acid metal salt, For example, gold, silver, copper, aluminum, zirconium, titanium, zinc, cerium, and the like can be given. As the metal phosphate, a combination of these can be used as appropriate.
Here, the phosphoric acid metal salt is the above-described phosphoric acid and an oxide or hydroxide containing the above-described metal (for example, gold hydroxide, silver oxide, copper hydroxide, aluminum hydroxide) in the presence of water. It can be obtained by reaction.

Of these, the metal phosphate is preferably gold phosphate, silver phosphate, copper phosphate, or aluminum phosphate. Among them, gold phosphate and silver phosphate are preferable because the adhesion between the inorganic reflective layer and the metal substrate is better, and the adhesion to the metal wiring layer (wiring adhesion) is unexpectedly better. More preferably, it is copper phosphate.

In the present invention, the metal constituting the metal substrate and the metal constituting the metal phosphate are the same type of metal because the adhesion between the inorganic reflective layer and the metal substrate is better. Is preferred. Among these, for reasons such as easy workability and high weather resistance, a mode in which a copper base is used as the metal base and copper phosphate is used as the inorganic binder (phosphate metal salt) is more preferable.

(Sodium silicate)
In the present invention, as an inorganic binder, sodium silicate as an optional component may be used in combination with the above-described phosphoric acid and / or metal phosphate.
The above-mentioned sodium silicate is also called sodium silicate or water glass, and Na ₂ SiO _3, which is a sodium salt of metasilicate, is commonly used. In addition, Na ₄ SiO ₄ , Na ₂ Si ₂ O ₅ , Na ₂ Si ₄ O ₉ or the like can also be used.
The sodium salt of metasilicic acid can be obtained by melting silicon dioxide with sodium carbonate or sodium hydroxide.
In addition, content in the case of using sodium silicate together is less than 50 mass% with respect to the total mass of an inorganic binder.

(Aluminum chloride)
In the present invention, as the inorganic binder, aluminum chloride may be used in combination with the above-described phosphoric acid and / or metal phosphate as an optional component.
The aluminum chloride may be any of anhydrous aluminum chloride, aluminum chloride hexahydrate, and polyaluminum chloride (a polymer of basic aluminum chloride formed by dissolving aluminum hydroxide in hydrochloric acid).
In addition, content in the case of using aluminum chloride together is less than 50 mass% with respect to the total mass of an inorganic binder.

<Inorganic particles>
The inorganic particles contained in the inorganic reflective layer are not particularly limited, but are preferably inorganic particles having a refractive index of 1.5 to 1.8 and an average particle diameter of 0.1 μm to 5 μm.
Here, the refractive index means a value measured at 25 ° C. according to “5. Measuring method of solid sample” of JIS K 0062: 1992.
The average particle diameter refers to the average value of the particle diameters of the inorganic particles. In the present invention, the average particle diameter refers to a 50% volume cumulative diameter (D50) measured using a laser diffraction particle size distribution analyzer.

By using inorganic particles satisfying such a refractive index and an average particle diameter, the reflectance of the reflective substrate of the present invention is increased, and the inorganic binder described above is a gap between inorganic particles or an inorganic particle and a metal group. Since it can enter into the gap with the material, the strength of the inorganic reflective layer is improved, and the adhesion between the inorganic reflective layer and the metal substrate is improved.
In the present invention, from the viewpoint of reflectance, the refractive index of the inorganic particles is preferably 1.55 or more and 1.75 or less, and the strength of the inorganic reflection layer and the adhesion between the inorganic reflection layer and the metal substrate. From this viewpoint, the average particle diameter of the inorganic particles is preferably 0.5 to 2 μm.

The kind of the inorganic particles is not particularly limited, and conventionally known oxides (for example, metal oxides), hydroxides (for example, metal hydroxides), inorganic salts (for example, carbonates, sulfates, etc.) , Fluoride (eg, lanthanum fluoride), silicon dioxide (silica), and the like can be used.
Of these, oxides, hydroxides, and inorganic salts are preferred because the reflectance of the reflective substrate of the present invention is high.

Specific examples of the inorganic particles include aluminum oxide (alumina) (refractive index n = 1.65 to 1.76, the numbers in parentheses in this paragraph indicate the refractive index), hydroxide Aluminum (1.58 to 1.65 to 1.76), calcium hydroxide (1.57 to 1.6), calcium carbonate (1.58), calcite (1.61), calcium carbonate (1.61) , Light calcium carbonate (1.59), heavy calcium carbonate (1.56), ultrafine calcium carbonate (1.57), gypsum (1.55), calcium sulfate (1.59), marble (1.57 ), Barium sulfate (1.64), barium carbonate (1.6), magnesium oxide (1.72), magnesium carbonate (1.52), magnesium hydroxide (1.58), strontium carbonate (1.52) , Orinkley (1.56), calcined clay (1.62), talc (1.57), sericite (1.57), optical glass (1.51-1.64), glass beads (1.51), etc. These may be used alone or in combination of two or more.
Among these, aluminum oxide, calcium hydroxide, and barium sulfate are preferable because the inorganic particles themselves have high whiteness and are advantageous in reflection characteristics.

In the present invention, two or more kinds of particles or two or more kinds of particles having an average particle diameter may be used in combination as the inorganic particles.
By using particles having different types and average particle diameters in combination, it is possible to improve the strength of the inorganic reflective layer and further improve the adhesion between the inorganic reflective layer and the metal substrate.

In the present invention, the shape of the inorganic particles is not particularly limited. For example, the shape is spherical, polyhedral (for example, icosahedron, dodecahedron, etc.), cubic, tetrahedral, or uneven on the surface of the sphere. Or a shape having a plurality of convex protrusions (hereinafter also referred to as “compete shape”), a plate shape, a needle shape, or the like may be used.
Among these, spherical, polyhedral, cubic, tetrahedral, and complex shapes are preferred for the reason of excellent heat insulation, and spherical is more preferred for reasons of easy availability and excellent heat insulation.

The inorganic reflective layer containing the inorganic binder and inorganic particles described above is preferably provided on the surface of the metal substrate in an amount such that the mass after heat drying is 20 g / m ² to 500 g / m ² .
The content of the inorganic binder and the inorganic particles in the inorganic reflective layer is preferably 5 to 100 parts by mass of the inorganic binder with respect to 100 parts by mass of the inorganic particles. Is more preferable.
Further, the inorganic reflective layer may contain other compounds in addition to the inorganic binder and the inorganic particles. Examples of other compounds include a dispersant and a reaction accelerator.

<Method for forming inorganic reflection layer>
In the present invention, the method for forming the inorganic reflective layer is not particularly limited. For example, a coating liquid (composition) containing the inorganic particles and the inorganic binder is screened on the surface of the metal substrate. It can be formed by a method such as applying and drying by printing or the like, and specifically, a method described in [0021] to [0023] of Patent Document 1.

[Surface shape]
The reflective substrate of the present invention has an arithmetic average roughness Ra (hereinafter referred to as the surface of the inorganic reflective layer), that is, the surface (excluding the surface of the portion where the light emitting element is mounted when the light emitting element is mounted). In addition, it is preferable that the average interval Psm (hereinafter also simply referred to as “Psm”) is 10 to 20 μm.
Here, “Ra” and “Psm” refer to surface property parameters described in JIS B0601: 2001, and in the present invention, both are stylus type surface roughness meters (for example, SURFCOM 480A, (Manufactured by Tokyo Seimitsu Co., Ltd.).

When the Ra of the surface of the reflective substrate is in the above range, the regular reflectance and the diffuse reflectance are good, and a reflective substrate for a light emitting device that can achieve high light emission efficiency can be obtained.
Similarly, when Psm on the surface of the reflective substrate is in the above range, the diffuse reflectance is improved, and the ratio of diffuse reflectance to regular reflectance (diffuse reflectance / regular reflectance) is to be greater than 95%. Can do.
From these viewpoints, in the present invention, Ra on the surface of the reflective substrate is preferably 0.65 to 0.90 μm, and Psm on the surface of the reflective substrate is preferably 10 to 15 μm.

(Wiring layer)
The reflective substrate of the present invention may have a wiring layer (metal wiring layer) when mounting the light emitting element.
In the present invention, the wiring layer may be provided on a part of the surface on which the light emitting element is mounted, or the surface on which the light emitting element is mounted (hereinafter referred to as “mounting surface” in this paragraph). .) May be provided on a part of the front surface (back surface) opposite to that and electrically connected to the mounting surface of the LED light emitting element via a through hole.

The material of the wiring layer is not particularly limited as long as it is a material that conducts electricity. Specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), Nickel (Ni) etc. are mentioned, These may be used individually by 1 type and may use 2 or more types together.
Of these, Cu is preferably used because of its low electrical resistance. Note that an Au layer or a Ni / Au layer may be provided on the surface layer of the wiring layer made of Cu from the viewpoint of improving the ease of wire bonding.

The thickness of the wiring layer is preferably 0.5 to 1000 μm, more preferably 1 to 500 μm, and particularly preferably 5 to 250 μm from the viewpoint of conduction reliability and package compactness.

As a method of forming the wiring layer, in addition to various plating processes such as an electrolytic plating process, an electroless plating process, and a displacement plating process, a sputtering process, a vapor deposition process, a vacuum bonding process for metal foil, and an adhesion process with an adhesive layer provided. Etc.
Among these, from the viewpoint of high heat resistance, the metal-only layer formation is preferable, and from the viewpoint of thick film / uniform formation and high adhesion, layer formation by plating is particularly preferable.

Since the plating process is a plating process for an inorganic material, it is preferable to use a technique in which a reduced metal layer called a seed layer is provided and then a thick metal layer is formed using the metal layer.
In addition, it is preferable to use electroless plating for the formation of the seed layer. The plating solution includes a main component (for example, a metal salt and a reducing agent) and an auxiliary component (for example, a pH adjusting agent, a buffering agent, a complex). It is preferable to use a solution composed of an agent, accelerator, stabilizer, improver, etc. As plating solutions, SE-650, 666, 680, SEK-670, 797, SFK-63 (all manufactured by Nihon Kanisen Co., Ltd.), Melplate NI-4128, Enplate NI-433, Enplate NI- Commercially available products such as 411 (all manufactured by Meltex Co., Ltd.) can be used as appropriate.
Further, when copper is used as the material for the wiring layer, various electrolytic solutions containing sulfuric acid, copper sulfate, hydrochloric acid, polyethylene glycol and a surfactant as main components and other various additives can be used.

The wiring layer thus formed is patterned by a known method according to the mounting design of the light emitting element. Further, a metal layer (including solder) is again provided at a place where the light emitting element is actually mounted, and can be appropriately processed so as to be easily connected by thermocompression bonding, flip chip, wire bonding, or the like.
As a suitable metal layer, a metal material such as solder or gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni) is preferable. From the viewpoint of mounting reliability, a method of providing Au or Ag via solder or Ni is preferable from the viewpoint of connection reliability.

If a pattern is formed by an inkjet printing method or a screen printing method using a metal ink described below as a method for forming a wiring layer, a wiring layer having a pattern can be easily formed without requiring many steps on an uneven surface. Can be formed.

<Inkjet printing method>
A wiring layer can be formed on a desired portion of the surface of the reflective substrate by ink jet printing using a metal ink containing a conductive metal. Specifically, a wiring pattern is formed with metal ink, and then fired to form a wiring.
Examples of the metal ink include those obtained by uniformly dispersing fine particles of a conductive metal in a solvent containing a binder, a surfactant, and the like. In this case, the solvent needs to have both affinity for the conductive metal and volatility.

Conductive metals contained in the metal ink include fine particles of metals such as silver, copper, gold, platinum, nickel, aluminum, iron, palladium, chromium, molybdenum, tungsten; silver oxide, cobalt oxide, iron oxide, ruthenium oxide, etc. Metal oxide fine particles; Cr—Co—Mn—Fe, Cr—Cu, Cr—Cu—Mn, Mn—Fe—Cu, Cr—Co—Fe, Co—Mn—Fe, Co—Ni—Cr—Fe, etc. Fine particles of a composite alloy of the above; fine particles of a plating composite such as silver plating and copper; and the like. These may be used alone or in combination of two or more.
Among these, metal fine particles are preferable, silver, copper, and gold are more preferable, oxidation resistance is excellent, it is difficult to form a high-insulation oxide, and the cost is low, and the conductivity after firing the wiring pattern is improved. For this reason, silver is particularly preferable.

The shape of the conductive metal that is a fine particle is not particularly limited, and examples thereof include a spherical shape, a granular shape, and a scaly shape. From the viewpoint of increasing the contact area between the fine particles and improving the conductivity, the scaly shape is preferable. preferable.
The average size of the conductive metal contained in the metal ink is preferably 1 to 20 nm, and more preferably 5 to 10 nm from the viewpoint of improving the conductivity by increasing the filling rate in the wiring pattern formed with the metal ink.

<Screen printing method>
A wiring pattern is formed on a desired portion of the surface of the reflective substrate by screen printing using a metal ink containing a conductive metal, and then fired to form a wiring.
The supply of the metallic ink by the screen printing method can be performed by providing a transmissive portion according to the wiring pattern on the screen and squeezing the metallic ink from the transmissive portion.
As a metal ink containing a conductor metal, what was used by the inkjet printing method mentioned above can be used.

[LED package]
Hereinafter, the LED package of the present invention will be described in detail.
The LED package of the present invention is an LED package having the above-described reflective substrate of the present invention and an LED light emitting element mounted on the surface thereof.
Next, the configuration of the LED package of the present invention will be described with reference to FIG.

FIG. 2 is a schematic cross-sectional view showing an example of a preferred embodiment of the LED package of the present invention.
As shown in FIG. 2, the LED package 20 has an LED light emitting element 12 mounted on the surface (inorganic reflective layer 3) of the reflective substrate 1 with an adhesive 11. The LED light emitting element 12 is molded with a transparent resin 14 mixed with fluorescent particles 13 and wire-bonded to the reflective substrate 1 of the present invention having the metal wiring layer 10 also serving as an electrode for external connection.

In the present invention, the LED light emitting element is a substrate in which a semiconductor such as GaAlN, ZnS, ZnSe, SiC, GaP, GaAlAs, AlN, InN, AlInGaP, InGaN, GaN, and AlInGaN is formed as a light emitting layer on a substrate. be able to.
Examples of the semiconductor structure include a homostructure, a heterostructure, or a double heterostructure having a MIS junction, a PIN junction, or a PN junction. Various emission wavelengths can be selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal.

The material of the transparent resin is preferably a thermosetting resin.
The thermosetting resin is preferably formed of at least one selected from the group consisting of epoxy resins, modified epoxy resins, silicone resins, modified silicone resins, acrylate resins, urethane resins, and polyimide resins. , Modified epoxy resin, silicone resin, and modified silicone resin are preferable.
Further, the transparent resin is preferably hard to protect the blue LED.
Moreover, it is preferable to use resin excellent in heat resistance, a weather resistance, and light resistance for transparent resin.
The transparent resin may be mixed with at least one selected from the group consisting of a filler, a diffusing agent, a pigment, a fluorescent material, a reflective material, an ultraviolet absorber, and an antioxidant so as to have a predetermined function. it can.

Furthermore, the said fluorescent particle should just absorb the light from blue LED and wavelength-convert it into the light of a different wavelength.
Specific examples of the fluorescent particles include nitride-based phosphors, oxynitride-based phosphors, sialon-based phosphors, and β-sialon-based phosphors that are mainly activated by lanthanoid elements such as Eu and Ce. An alkaline earth halogen apatite phosphor, an alkaline earth metal borate phosphor, an alkaline earth metal aluminate phosphor mainly activated by a lanthanoid group such as Eu, or a transition metal group element such as Mn; Alkaline earth silicate phosphor, alkaline earth sulfide phosphor, alkaline earth thiogallate phosphor, alkaline earth silicon nitride phosphor, germanate phosphor; mainly activated by lanthanoid elements such as Ce Rare earth aluminate phosphors, rare earth silicate phosphors, organic complexes mainly activated by lanthanoid elements such as Eu, etc., and these may be used alone, It may be used in combination with more species.

On the other hand, the LED package of the present invention can also be used as a phosphor-mixed white LED package using an ultraviolet to blue LED and a fluorescent light emitter that absorbs the LED and emits fluorescence in the visible light region.
These fluorescent light emitters absorb blue light from the blue LED to generate fluorescence (yellowish fluorescent light), and white light is emitted from the light emitting element by the fluorescent light and the afterglow of the blue LED.
The above-described method is a so-called “pseudo white light emission type” in which a blue LED light source chip and one kind of yellow phosphor are combined. In addition, for example, an ultraviolet to near ultraviolet LED light source chip and a red / green / blue fluorescence. The LED of the present invention as a light-emitting unit using a known light-emitting method such as “ultraviolet to near-ultraviolet light source type” in which several kinds of bodies are combined and “RGB light source type” that emits white light with three red / green / blue light sources Package can be used.

In the LED package of the present invention, the method of mounting the LED light emitting element on the reflective substrate of the present invention involves mounting by heating, but the thermocompression bonding including solder reflow and the mounting method by flip chip provide uniform and reliable mounting. In view of the above, the maximum reached temperature is preferably 220 to 350 ° C, more preferably 240 to 320 ° C, and particularly preferably 260 to 300 ° C.
The time for maintaining these maximum temperatures is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.

Also, the temperature at the time of mounting by wire bonding is preferably 80 to 300 ° C., more preferably 90 to 250 ° C., and particularly preferably 100 to 200 ° C. from the viewpoint of reliable mounting. The heating time is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

(Preparation of binder liquid)
Binder liquids A to D used for the inorganic reflection layer forming solution were prepared.

<Binder liquid A (inorganic binder: copper phosphate)>
Phosphoric acid 85% (Wako Pure Chemical) 48g
Copper hydroxide (II) (Wako Pure Chemical Industries) 9g
Water 41g

<Binder liquid B (inorganic binder: silver phosphate)>
Phosphoric acid 85% (Wako Pure Chemical) 48g
Silver oxide (Wako Pure Chemical) 16g
Water 41g

<Binder liquid C (inorganic binder: gold phosphate)>
Phosphoric acid 85% (Wako Pure Chemical) 48g
Gold hydroxide (III) (Wako Pure Chemical) 35g
Water 41g

<Binder liquid D (inorganic binder: aluminum phosphate)>
Phosphoric acid 85% (Wako Pure Chemical) 48g
Aluminum hydroxide (Wako Pure Chemicals) 11g
Water 41g

[Production of reflective substrate]
<Examples 1 to 19 and Comparative Examples 1 to 5>
An inorganic reflective layer forming solution was prepared by adding 100 g of inorganic particles shown in Table 1 below to 100 g of binder liquid having the composition shown in Table 1 below and stirring.
After the prepared inorganic reflective layer forming solution is applied on the metal substrate shown in Table 1 below to form a coating film, the inorganic reflective layer is formed on the metal substrate by drying at 200 ° C. for 5 minutes. A reflective substrate was prepared.
The presence of the metal phosphate (inorganic binder) in the inorganic reflective layer was confirmed by infrared spectroscopy (IR).

<Measurement of surface shape>
About the surface shape of the produced reflective board | substrate, Ra and Psm were measured using the stylus type surface roughness meter (SURFCOM480A, Tokyo Seimitsu Co., Ltd. make). These results are shown in Table 1 below.

<Heat dissipation (thermal conductivity)>
About the produced reflective board | substrate, the thermal diffusivity was computed according to the t1 / 2 method using TC-9000 / laser flash type thermal diffusivity measuring apparatus by ULVAC-RIKO Inc., and the thermal conductivity was computed from the following formula. The results are shown in Table 1 below.
Thermal conductivity λ = α × Cp × ρ
(In the formula, α represents thermal diffusivity, Cp represents specific heat, and ρ represents density.)

<Adhesiveness>
The adhesiveness (adhesion) between the inorganic reflective layer and the metal substrate of the produced reflective substrate was cut into 30 mm × 30 mm (planar square shape) with a push cutter, and the substrate that did not peel off was 3 m in height from the concrete. It was dropped on the ground and evaluated according to the following criteria.
Further, the temperature rise and fall between −50 ° C. and 400 ° C. was set to one cycle (4 hours / cycle), and the same test was performed on the reflective substrate after 100 cycles (after the heat cycle).
These results are shown in Table 1 below.
A: not peeled B: partially peeled but no problem in practical use C: peeled D: peeled off when cut with a push cutter

<Reflectance>
With respect to the produced reflective substrate, the total reflectance (total average in the SPIN mode) of 400 to 700 nm was measured using a reflection densitometer (CM2600D, manufactured by Konica Minolta, Inc.). The results are shown in Table 1 below.

<Wiring adhesion>
A diluted metal nanoparticle ink (XA-436, manufactured by Fujikura Kasei Co., Ltd.) using an ink jet apparatus (DMP-2831, manufactured by Fuji Film Co., Ltd.) is applied to the surface of the prepared reflective substrate. Ag wiring (wiring width: 100 μm) was formed by droplet ejection with 10 patterns.
Thereafter, the entire reflective substrate was pressed with a roller to flatten the surface of the Ag wiring, and a nickel layer was formed on the Ag wiring. Specifically, using an electroless nickel plating solution (ICP-Nicolon GM (NP)) manufactured by Okuno Pharmaceutical Co., Ltd., the surface was flattened by immersion treatment at a temperature of 75 ° C. and a pH of 7.5 for 25 minutes. A nickel layer was formed on the Ag wiring. The treated substrate was carefully washed with pure water.
Next, a substitution type electroless gold plating solution (non-electric noble AU) manufactured by Okuno Pharmaceutical Industry Co., Ltd. was used to form an Au layer on the nickel layer, and then a reduced electroless gold plating solution manufactured by Okuno Pharmaceutical Industry Co., Ltd. (self Gold OKT-IT) was used to increase the thickness of the Au layer. Note that the substrate was carefully washed with pure water after each treatment.
The formed metal wiring layer was evaluated according to the following criteria. The results are shown in Table 1 below.
A: When observed with an optical microscope, the wiring is almost straight, and the wiring layer cannot be peeled off when the tape is applied and peeled B: The wiring shape is disturbed when the tape is attached and peeled off C: Tape Wiring peels off when affixed and peeled off D: Wiring is not continuous and missing

In Table 1, the following were used as inorganic particles.
Aluminum oxide (refractive index: 1.65, average particle size: 0.52 μm): AL-160SG-3 (manufactured by Showa Denko KK)
Aluminum oxide (refractive index: 1.65, average particle size: 0.10 μm): AL-160SG-3 (average particle size: 0.52 μm, manufactured by Showa Denko KK) with a zirconia bead using a ball mill After pulverizing and using a particle size measuring device, the average particle size becomes 0.10 μm.
Aluminum oxide (refractive index: 1.65, average particle size: 4.70 μm): A42-2 (manufactured by Showa Denko KK)
Calcium hydroxide (refractive index: 1.57, average particle size: 1.00 μm): CSH (manufactured by Ube Materials Corporation)
Barium sulfate (refractive index: 1.64, average particle size: 0.30 μm): B-30 (manufactured by Toshin Kasei Co., Ltd.)
Lanthanum fluoride (refractive index: 1.59, average particle size: 0.90 μm): # 124-03532 (manufactured by Wako Pure Chemical Industries, Ltd.)
Barium carbonate (refractive index: 1.60, average particle size: 0.85 μm): # 022-111792 (manufactured by Wako Pure Chemical Industries, Ltd.)
Silicon dioxide (refractive index: 1.45, average particle size: 0.80 μm): # 199-00625 (manufactured by Wako Pure Chemical Industries, Ltd.)

From the results shown in Table 1, it was found that when an aluminum substrate was used, the adhesion to the inorganic reflective layer was good, but the heat dissipation was poor (Comparative Examples 1 to 5).
On the other hand, when an inorganic reflective layer is formed using gold, silver or copper as a base material and a metal phosphate as an inorganic binder, the heat dissipation is excellent, and the adhesive between the inorganic reflective layer and the base material is excellent. (Examples 1 to 19).
In particular, from the comparison between Examples 1 to 10 and Examples 11 to 13, by using copper phosphate, silver phosphate or gold phosphate as the inorganic binder, the adhesion between the inorganic reflective layer and the metal substrate is improved. It was found that (especially before the heat cycle) was good, and adhesion (wiring adhesion) with the metal wiring layer was good.
Further, from the comparison between Examples 1 to 9 and Examples 10 to 13 (particularly Example 10), it is found that the metal constituting the metal substrate and the metal constituting the metal phosphate are the same type of metal It was found that the adhesion between the reflective layer and the metal substrate (particularly after heat cycle) was good.
Further, from the comparison between Examples 1 to 5 and Examples 14 and 15, when the inorganic particles are oxides, hydroxides or inorganic salts, particularly aluminum oxide, calcium hydroxide or barium sulfate, reflection It was found that the rate was improved.
Further, from the comparison between Example 1 and Example 16, it was found that the heat dissipation was further improved when the thickness of the metal substrate was 0.10 to 3 mm.
Further, in comparison with Example 1 and Example 17, when the arithmetic average roughness Ra of the surface is 0.50 to 1.00 μm and the average interval Psm of the unevenness is 10 to 20 μm, the metal wiring layer It was found that the adhesiveness (wiring adhesiveness) was improved.
Further, from the comparison between Example 1 and Examples 18 and 19, when the refractive index of the inorganic particles is 1.5 or more and 1.8 or less and the average particle diameter is 0.1 μm or more and 5 μm or less, reflection It was found that the rate was improved.

DESCRIPTION OF SYMBOLS 1 Reflective substrate 2 Metal base material 3 Inorganic reflective layer 4 Inorganic particle 5 Inorganic binder 6 Thermosetting resin 10 Metal wiring layer 11 Adhesive 12 LED light emitting element 13 Fluorescent particle 14 Transparent resin 20 LED package

Claims

A metal substrate and an inorganic reflective layer provided on at least a part of the surface of the metal substrate;
The metal substrate is composed of at least one metal selected from the group consisting of gold, silver and copper;
A reflective substrate, wherein the inorganic reflective layer contains an inorganic binder containing phosphoric acid and / or a metal phosphate and inorganic particles.
The reflective substrate according to claim 1, wherein the metal phosphate is at least one selected from the group consisting of gold phosphate, silver phosphate and copper phosphate.
The reflective substrate according to claim 1 or 2, wherein the metal constituting the metal substrate and the metal constituting the metal phosphate are the same kind of metal.
The reflective substrate according to any one of claims 1 to 3, wherein the inorganic particles have a refractive index of 1.5 or more and 1.8 or less and an average particle diameter of 0.1 µm or more and 5 µm or less.
The reflective substrate according to any one of claims 1 to 4, wherein the inorganic particles are at least one selected from the group consisting of oxides, hydroxides, and inorganic salts.
6. The reflective substrate according to claim 1, wherein the inorganic particles are at least one selected from the group consisting of aluminum oxide, calcium hydroxide, and barium sulfate.
The reflective substrate according to any one of claims 1 to 6, wherein the metal substrate has a thickness of 0.1 to 3 mm.
The reflective substrate according to any one of claims 1 to 7, wherein the arithmetic average roughness Ra of the surface is 0.50 to 1.00 µm, and the average interval Psm of the unevenness is 10 to 20 µm.
9. An LED package comprising the reflective substrate according to any one of claims 1 to 8 and an LED light emitting element mounted on a surface thereof.