JP2016170410A - Method for producing reflection substrate and reflection substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate having a high reflectance of light in a near-ultraviolet region.SOLUTION: A method for producing a reflection substrate includes a step of forming a reflection layer on at least a part of a region on a base substrate with spherical inorganic particles by a powder spray coating method.SELECTED DRAWING: None

Description

  The present invention relates to a method for manufacturing a reflective substrate and a reflective substrate.

  Generally, an LED (Light Emitting Diode) device includes a substrate, an LED element mounted on the substrate, and a sealing member including a phosphor that seals the LED element. Light from the LED element (hereinafter also referred to as “LED light”) is emitted in all directions, and the LED light excites the phosphor, and the desired color is obtained by the excitation light or the combination of the excitation light and the LED light. Created.

  Of the LED light, light directed to the substrate is reflected by the substrate and becomes reflected light. However, a conventionally used substrate has a low reflectance of light in the near ultraviolet region (near ultraviolet light). For this reason, when a near-ultraviolet LED element is used, the amount of reflected light in the near-ultraviolet region is reduced, so that the efficiency of exciting the phosphor is considered to be low. Therefore, in the prior art, measures such as increasing the content of the phosphor in the sealing member or increasing the output of the LED element are taken.

  For example, as in Patent Document 1, in the near-ultraviolet region, obtained by spraying an adherend containing inorganic particles and a binder onto the surface of a base material by a spray coating method and then performing preliminary firing to form a porous layer. A reflective member having a high reflectance is known.

JP 2011-180618 A

  The porous layer of Patent Document 1 is formed by sintering at a temperature of 950 ° C. or higher. However, if an adhering material layer is formed on an aluminum substrate or a resin substrate and pre-baked, the metal or wiring on the substrate is thermally oxidized due to the influence of heat. Various troubles such as shape distortion occur.

The present inventors have intensively studied to solve the above problems. As a result, for example, it has been found that the above problem can be solved by the following configuration, and the present invention has been completed.
The present invention relates to the following [1] to [8], for example.

[1] A method for producing a reflective substrate, comprising using a spherical inorganic particle to form a reflective layer in at least a partial region on a base substrate by a powder spray coating method.
[2] The method for producing a reflective substrate according to [1], wherein 70% or more (number basis) of the spherical inorganic particles are particles having a particle diameter in a range of 20 to 60 μm.
[3] The method for producing a reflective substrate according to [1] or [2], wherein the spherical inorganic particles are spherical granulated powder obtained by a spray drying method.
[4] The spherical inorganic particles according to any one of [1] to [3], wherein the spherical inorganic particles are particles containing at least one selected from ZrO ₂ , SiO ₂ , Al ₂ O ₃ and AlN. A method for manufacturing a reflective substrate.
[5] The method for manufacturing a reflective substrate according to any one of [1] to [4], wherein the material of the reflective layer forming region in the base substrate is aluminum, titanium, or stainless steel.
[6] The method for manufacturing a reflective substrate according to any one of [1] to [5], wherein the thickness of the reflective layer is in a range of 1 μm or more.
[7] A reflective substrate having a base substrate and a reflective layer formed in at least a partial region on the base substrate by a powder spray coating method using spherical inorganic particles.
[8] The reflective substrate according to [7], which is an LED element mounting substrate.

  According to the present invention, it is possible to form a reflective layer having a high reflectance of light in the near ultraviolet region on an existing substrate without performing a high-temperature heat treatment step, and the reflectance of light in the near ultraviolet region is high. A reflective substrate can be provided.

FIG. 1 is a diagram illustrating a film forming apparatus used in a powder gasification deposition method. FIG. 2 is an SEM image of spherical inorganic particles used in the examples. FIG. 3 is an SEM image of non-spherical inorganic particles used in the comparative example. FIG. 4 is a graph showing the reflectance of a single inorganic particle used in the examples and the reflectances of an aluminum substrate, a titanium substrate, and a SUS substrate. FIG. 5A is a graph showing the reflectivity of the reflective substrate and the like obtained in Examples and Comparative Example A. FIG. 5B is a graph showing the reflectance of the reflective substrate and the like obtained in the example and the comparative example A. FIG. 5C is a graph showing the reflectivity of the reflective substrate and the like obtained in Examples and Comparative Example A. FIG. 6A is a graph showing the reflectivity of the reflective substrate and the like obtained in Examples and Comparative Example B. FIG. FIG. 6B is a graph showing the reflectivity of the reflective substrate and the like obtained in Example and Comparative Example B. FIG. 6C is a graph showing the reflectivity of the reflective substrate and the like obtained in Example and Comparative Example B. FIG. 7A is a graph showing the reflectivity of the reflective substrate and the like obtained in Example and Comparative Example C. FIG. FIG. 7B is a graph showing the reflectivity of the reflective substrate and the like obtained in Example and Comparative Example C. FIG. 7C is a graph showing the reflectivity of the reflective substrate and the like obtained in Examples and Comparative Example C.

Hereinafter, the present invention will be described in detail.
In this specification, the near-ultraviolet region means a range of wavelengths from 360 nm to 400 nm and the visible light region means a range of wavelengths exceeding 400 nm to 740 nm or less.

[Method of manufacturing reflective substrate]
The method for producing a reflective substrate of the present invention includes a step of forming a reflective layer in at least a partial region on a base substrate by powder injection coating using spherical inorganic particles.

<Inorganic particles>
In the present invention, spherical inorganic particles are used to form the reflective layer on the base substrate. The spherical inorganic particles used in the present invention preferably have a reflectance higher than the reflectance of the base substrate on which the reflective layer is formed in at least a part of the wavelength range of 360 nm to 400 nm.

  The reflectance of the inorganic particles in the near ultraviolet region is measured as follows. After sufficiently disposing the inorganic particles on the substrate so that the substrate is not visible, another substrate is placed on the inorganic particle layer to flatten the inorganic particle layer. After planarization, the substrate placed on the layer of inorganic particles is removed. The reflectance in the wavelength range of 360 to 740 nm is measured using a spectrocolorimeter for the inorganic particle layer thus obtained. In this manner, the reflectance of the inorganic particles in the wavelength range of 360 nm to 400 nm is obtained. In addition, the layer of an inorganic particle should just be planarized, and should just planarize an inorganic particle with flat members other than a board | substrate.

  The reflectance of the spherical inorganic particles used to form the reflective layer is higher than the reflectance of the base substrate on which the reflective layer is formed in at least a part of the near ultraviolet region (360 nm to 400 nm). Is preferred. Here, it is more preferable that the reflectance of the spherical inorganic particles exceeds the reflectance of the base substrate in the above-described all near-ultraviolet region, but it is only necessary to partially exceed the reflectance. For example, spherical inorganic particles whose reflectance in the range of 380 to 400 nm is higher than that of the base substrate, or spherical inorganic particles whose reflectance near 360 nm is higher than that of the base substrate may be used. Or the spherical inorganic particle whose average reflectance in a near ultraviolet region is higher than a base substrate may be sufficient.

As the inorganic particles, particles containing at least one selected from ZrO ₂ , SiO ₂ , Al ₂ O ₃ and AlN are more preferably used.
Moreover, 1 type of inorganic particles may be used and 2 or more types of inorganic particles may be used.

In the present specification, particles having a content ratio of a certain component X constituting the particles of 50% by mass or more are referred to as X particles. For example, particles having a ZrO ₂ content of 50% by mass or more constituting the particles are described as ZrO ₂ particles.

Examples of the inorganic particles include ZrO ₂ particles, SiO ₂ particles, Al ₂ O ₃ particles, and AlN particles. Among these, ZrO ₂ particles and Al ₂ O ₃ particles are used from the viewpoint of high reflectance in the near ultraviolet region. Particles are preferable, and ZrO ₂ particles are more preferable from the viewpoint of high reflectance in the visible light region. When considering thermal conductivity such as heat dissipation in addition to the purpose of reflectivity, the thermal conductivity is higher for AlN particles, followed by Al ₂ O ₃ particles, then ZrO ₂ particles, to ensure heat dissipation Is preferably AlN particles or Al ₂ O ₃ particles.

  By using spherical inorganic particles, it is possible to form a low-density reflective layer containing a large amount of voids inside on the base substrate. Thereby, the reflectance in the near ultraviolet region can be improved. In the present invention, it is more preferable to use spherical (granular) ceramic particles obtained by granulating primary particles and / or secondary particles in which primary particles are aggregated.

  The spherical inorganic particles preferably have a circularity of 0.9 or more, more preferably 0.95 or more. In particular, the circularity of the particle diameter in the range of 20 to 60 μm is preferably in the above range. Such circular particles are obtained, for example, by a spray drying method described later.

  As the spherical inorganic particles, it is preferable to use particles having 70% or more and a particle diameter in the range of 20 to 60 μm. Here, the ratio is based on the number, and is a ratio with respect to all inorganic particles having a particle diameter of 5 μm or more. Inorganic particles containing particles having a particle diameter of 20 μm or more in the above range are preferable for forming a reflective layer having a low density. In addition, when inorganic particles containing particles having a particle diameter of more than 60 μm in excess of 30% are used, the present invention adopting a powder injection coating method as a film forming method tends to be difficult to deposit without forming a film. The ratio of the inorganic particles having the particle diameter can be calculated, for example, by measuring the particle diameter of an arbitrary particle from a scanning electron microscope (SEM) photograph.

  As the spherical inorganic particles, it is preferable to use inorganic particles having a median diameter (D50; number basis) in the range of 20 μm or more, and more preferable to use inorganic particles in the range of 20 to 60 μm. The median diameter is measured by an SEM observation image.

  The spherical inorganic particles are preferably spherical granulated powder obtained by spray drying. Specifically, it is preferably a spherical (granular) powder obtained by granulating the primary particles and / or secondary particles formed by agglomerating the primary particles as a raw material by a spray drying method. . The spray drying method is preferable for obtaining spherical inorganic particles. The conditions of the spray drying method are not particularly limited as long as particles having a spherical shape and a particle diameter in the above range are obtained. Since a known technique can be used for the spray drying method, description thereof is omitted. The shape and size of the prepared particles can be changed by appropriately setting, for example, the spraying amount and spraying state of spray drying, and the temperature.

<Base substrate>
Examples of the material of the reflective layer formation region in the base substrate include metals (including alloys) such as aluminum, titanium, and stainless steel (for example, SUS430, SUS304, and SUS316 defined in JIS standards). Examples of the base substrate include a metal substrate such as an aluminum substrate, a titanium substrate, and a stainless steel substrate; a synthetic resin substrate such as an epoxy resin substrate; an aluminum layer, a titanium layer, and a stainless steel layer on the surface of the synthetic resin substrate. A laminated substrate in which a metal layer such as aluminum is formed; an alloy substrate mainly composed of aluminum, titanium, and iron; and a laminated substrate; a substrate in which a protective layer such as a glass film is formed on these substrates. When a metal substrate is used as the base substrate, heat dissipation from the back surface of the base substrate is enhanced. For example, when an LED element is mounted on the base substrate, the temperature distribution of the base substrate during light emission can be equalized. . For this reason, it is preferable at the point which can suppress the dispersion | variation in LED light.

Among these, an aluminum substrate is preferable as a base substrate because it has a high reflectance at a wavelength exceeding 400 nm and not exceeding 740 nm. For example, an aluminum substrate having an average reflectance of more than 80 nm and not more than 740 nm is preferably 80% or more, more preferably 90% or more.
Although a base substrate is not specifically limited, As a shape, flat shape is mentioned, for example. The thickness of the base substrate is usually about 0.5 to 2 mm.

<Film formation method>
In the present invention, a powder spray coating method is used as a film forming method for forming the reflective layer in at least a part of the region on the base substrate. In the present invention, the “powder spray coating method” means that a raw material powder is dispersed in a carrier gas to form a powder gas, and the powder in the powder gas collides with the target substrate by spraying the powder gas toward the target substrate. It means a method of depositing and forming a film made of a material constituting the powder on a target substrate. In addition, powder gas means the mixture of the glass powder which floats in gas, and the gas.

  The powder spray coating method does not require any heating means and can form a film at room temperature. Further, by using the powder spray coating method, the reflective layer can be directly formed on the base substrate without using, for example, an adhesive layer or the like. In the powder spray coating method, film formation can be performed only by powder spraying, and firing is not required. Therefore, damage to the base substrate is small, and the number of substrate options can be increased.

  Specific examples of the powder spray coating method include a powder gasification deposition method (GD method) and a powder jet deposition method (PJD method). Generally, the GD method is a method performed in a film formation environment under reduced pressure, and the PJD method is a method performed in a film formation environment under atmospheric pressure. Any method can be adopted in the present invention.

In the present invention, the spherical inorganic particles are used as the raw material powder, and the base substrate is used as the target substrate.
The pressure in the film forming chamber is preferably 10 to 1000 Pa, more preferably 10 to 400 Pa, and still more preferably 20 to 200 Pa. When the pressure is in the above range, the resulting film does not become too dense, which is preferable for obtaining a substrate having a high reflectance of light in the near ultraviolet region.

Examples of the carrier gas include an inert gas such as helium (He), argon (Ar), and nitrogen (N ₂ ), and dry air. The gas flow rate of the carrier gas is not particularly limited as long as it is a flow rate capable of maintaining the generation and conveyance of the desired powder gas, but is preferably 0.1 to 10 L / min, more preferably 0.5 to 5 L / min, and still more preferably. Is 0.5-2 L / min. When the gas flow rate is within the above range, the resulting film does not become too dense, which is preferable for obtaining a substrate having a high reflectance of light in the near ultraviolet region.

The atmospheric temperature in the film forming chamber is usually about 5 to 35 ° C.
The thickness of the reflective layer to be formed is usually 1 μm or more, preferably 10 to 1000 μm, more preferably 100 to 300 μm. If the thickness of the reflection layer to be formed is not less than the lower limit of the above range, a high reflectance tends to be obtained in the near ultraviolet region, and it is preferable from the viewpoint of film formation control.

When ZrO ₂ particles, SiO ₂ particles, Al ₂ O ₃ particles, AlN particles and the like are used as the inorganic particles, the formed reflective layer has high insulating properties. Therefore, according to the present invention, it is possible to obtain a reflective substrate having a reflective layer having high insulating properties and high near-UV reflectance.

  FIG. 1 shows an example of a schematic diagram of a film forming apparatus for forming a film by the GD method. The film forming apparatus 1 includes a gas cylinder 120, a gas introduction unit 40, a mixing unit 110, a powder tank 10, a film formation chamber 20, a vacuum pump 30, a powder gas introduction unit 50, and an exhaust pipe 60. .

  The mixing unit 110 is a container in which powder gas is generated, and the mixing unit 110 is connected to the powder tank 10 containing the raw material powder 70. A gas introduction unit 40 and a powder gas introduction unit 50 are connected to the mixing unit 110.

  The gas introduction unit 40 introduces a carrier gas used for conveying the raw material powder 70 into the mixing unit 110. The raw material powder 70 and the carrier gas are mixed in the mixing unit 110 to generate a powder gas. The powder gas introduction unit 50 sucks the generated powder gas and introduces it into the film forming chamber 20. An injection nozzle 80 having a slit is provided at the tip of the powder gas introduction unit 50.

  In the film formation chamber 20, film formation is performed by the GD method. A mixing unit 110 is connected to the film forming chamber 20 by a powder gas introduction unit 50, and a vacuum pump 30 is connected by an exhaust pipe 60. The pressure inside the film forming chamber 20 can be controlled to an arbitrary reduced pressure state by the vacuum pump 30.

  A movable stage 90 is provided inside the film forming chamber 20, and the target substrate 100 is fixed to the movable stage 90. The movable stage 90 is movable in order to adjust the relative position between the target substrate 100 and the ejection nozzle 80.

  The powder gas generated in the mixing unit 110 passes through the powder gas introducing unit 50, is introduced into the film forming chamber 20 from the spray nozzle 80, and is sprayed toward the target substrate 100 fixed to the movable stage 90.

  By the above film forming method, for example, a reflective layer having a high reflectance with respect to near ultraviolet rays emitted from the LED element can be formed in an arbitrary region on the base substrate. Therefore, the reflective substrate obtained by the production method of the present invention can be suitably used as an LED element mounting substrate.

  Since the reflectance in the near ultraviolet region can be increased by using the reflective substrate obtained in the present invention as the LED element mounting substrate, the probability of exciting the phosphor is improved. Thereby, content of the fluorescent substance in a sealing member can be reduced, For this reason, the extraction efficiency of the synthetic light of excitation light or excitation light and LED light can be raised. In addition, the output of the LED element can be lowered, which can contribute to power saving.

[Reflective substrate]
The reflective substrate of the present invention includes a base substrate and a reflective layer formed on at least a part of the region on the base substrate by a powder spray coating method using spherical inorganic particles.

  In the reflective substrate of the present invention, the reflectance of light in at least a part of the wavelength range of 360 to 400 nm on the reflective layer surface is preferably higher than the reflectance of the base substrate alone.

  For example, pseudo white light can be obtained by combining a near-ultraviolet LED element and a red, green, or blue phosphor. If a reflective substrate having a high light reflectance at a wavelength of 360 to 400 nm is used as the LED element mounting substrate, the probability that the reflected light of the LED light reflected by the substrate in the above wavelength range also contributes to the excitation of the phosphor is high. Get higher. Therefore, it is preferable in terms of reducing the amount of phosphor used and saving power.

  The higher the average reflectance of light in the visible light region, the higher the luminance of the LED element. Moreover, when obtaining the above-mentioned pseudo white light, it is preferable that the reflectance of light is substantially constant in the visible light region.

The reflective substrate of the present invention can be produced based on the above-mentioned [Production method of reflective substrate].
Hereinafter, an example in which the reflective substrate of the present invention is used as an LED element mounting substrate will be described. Specifically, a method for manufacturing the LED device will be described. The LED device includes, for example, a step of mounting an LED element on a reflective layer of an LED element mounting substrate (hereinafter also referred to as “substrate Z”) on which a reflective layer and a circuit pattern are formed, and the LED element mounted on the substrate Z And a circuit pattern of the substrate Z, and a step of sealing the LED element using a translucent sealing material.

The configuration of the substrate Z is, for example, as follows.
When the base substrate is a metal substrate such as an aluminum substrate, a reflective layer also serving as an insulating layer is formed on the base substrate, a metal foil is laminated on the reflective layer, and an etching process is performed on the metal foil. Thus, a circuit pattern can be formed. An example of the metal foil is a copper foil. In addition, a circuit pattern can be formed by a known means.

  When the base substrate is a laminated substrate in which a metal layer such as an aluminum layer is formed on a synthetic resin substrate, an electrode layer to be a circuit pattern is formed by the metal layer, and the LED element and the electrode layer are The reflective layer described above can be formed in a region other than the portion to be conducted.

  For example, the LED element is mounted on the substrate Z via a translucent adhesive. Examples of the translucent adhesive include die bond agents such as epoxy resins, urea resins, acrylic resins, and silicone resins.

The LED element mounted on the substrate Z is electrically connected to a circuit pattern formed on the substrate Z by a known means such as wire bonding or flip chip.
The LED element is resin-sealed using a sealing material containing a translucent resin and a phosphor. Since the LED device has a substrate with a high reflectance of light in the near ultraviolet region, as described above, the amount of phosphor in the sealing material can be reduced. For this reason, since the excitation light of the phosphor is extracted without being absorbed by another phosphor, the light emission efficiency from the LED device is increased.

  In one embodiment of the LED device, since the plurality of LED elements are bonded on the reflective layer via a translucent adhesive, it is not necessary to form the reflective layer so as to correspond to the individual LED elements. .

  In the LED device described above, part of the light emitted from the LED element is directed to the reflective layer of the LED element mounting substrate, contrary to the normal light extraction direction. The light traveling toward the reflective layer is reflected toward the normal light extraction direction on the reflective layer surface.

Hereinafter, the present invention will be described more specifically based on examples.
[Preparation Example 1]
A method for preparing spherical ZrO ₂ granulated particles will be described.

First, the zirconium hydroxide powder is put into a furnace set at 900 ° C. to 1000 ° C. and calcined for about 2 hours to obtain ZrO ₂ fine powder. Next, ZrO ₂ fine powder is mixed with a liquid composed of water and an organic solvent to prepare a slurry. Here, the mixing ratio is such that the mass of ZrO _{2 and} the mass of the liquid are approximately the same. Then, secondary particles formed by agglomerating primary particles and / or primary particles having a small particle diameter by mixing and pulverizing the slurry and balls for pulverization with a stirring tank type medium agitation pulverizer for 6 hours. It becomes a slurry containing. When the slurry thus prepared is sprayed in a high-temperature air flow at 150 ° C. by a spray drying method, secondary particles formed by agglomeration of primary particles and / or primary particles having a small particle diameter due to surface tension are further agglomerated. It becomes a spheroidized droplet. The droplets are dried as they are to obtain ZrO ₂ granulated particles.

With respect to the obtained granulated particles of ZrO ₂ , photographs taken with a scanning electron microscope (SEM) are shown in FIG. 2 (a) (5 kV, 1000 times) and FIG. 2 (b) (5 kV, 200 times). It was confirmed that the obtained ZrO ₂ granulated particles were spherical (granular).

As a result of measuring and calculating the particle diameter of an arbitrary particle from the SEM photograph, the particle diameter of the spherical (granular) ZrO ₂ granulated particles is about 77% (number basis) of 20 to 20 μm or more. It was in the range of 60 μm, and the median diameter (D50) was 29 μm. In addition, the circularity of the particle diameter in the range of 20 to 60 μm was 0.9 or more. Thus the powder of the granulated particles of ZrO ₂ obtained is referred to as a ZrO ₂ granulated powder.

[Preparation Example 2]
Granulated particles of Al ₂ O ₃ are obtained according to Preparation Example 1 except that aluminum hydroxide powder is used instead of zirconium hydroxide powder. The obtained granulated particles of Al ₂ O ₃ were observed with a scanning electron microscope (SEM) and confirmed to be spherical (granular). As a result of measuring and calculating the particle diameter of an arbitrary particle from the SEM photograph, the particle diameter of spherical (granular) Al ₂ O ₃ granulated particles is about 81% (number basis) of particles of 5 μm or more. The median diameter (D50) was 46.8 μm. In addition, the circularity of the particle diameter in the range of 20 to 60 μm was 0.9 or more. Thus the powder of the granulated particles of Al ₂ O ₃ obtained is referred to as Al ₂ O ₃ granulated powder.

[Preparation Example 3]
After obtaining a spherical granule according to Preparation Example 1 by spray drying method using alumina powder or alumina hydrate powder instead of zirconium hydroxide powder, it is 1200 to 1800 ° C. in a nitrogen atmosphere containing a reducing agent. The granulated particles of AlN are obtained by performing heat treatment and reductive nitriding treatment at a temperature of The obtained granulated particles of AlN were observed with a scanning electron microscope (SEM) and confirmed to be spherical (granular). As a result of measuring and calculating the particle diameter of an arbitrary particle from the SEM photograph, the particle diameter of the spherical (granular) AlN granulated particles is about 60% to about 83% (number basis) of particles of 5 μm or more. The median diameter (D50) was 40.5 μm. In addition, the circularity of the particle diameter in the range of 20 to 60 μm was 0.9 or more. The powder of the granulated particles of AlN obtained in this way is called AlN granulated powder.

[Comparative Preparation Example 1]
Next, a method for preparing sintered and pulverized particles of ZrO ₂ will be described as a comparative example.
First, a ZrO ₂ fine powder raw material is pressed by a mold press at a molding pressure of 500 to 700 kgf / cm ² to produce a powder compact. This is fired at 1200 to 1900 ° C. for 2 hours to obtain a high-density sintered body. The sintered body is pulverized with a pulverizer and then classified to obtain ZrO ₂ pulverized particles.

FIG. 3 shows a photograph of the ZrO ₂ pulverized particles thus obtained by a scanning electron microscope (SEM; 5 kV, 1000 times). It was confirmed that the ZrO ₂ pulverized particles were not spherical but angular. Further, the median diameter (D50) was determined in the same manner as described above. As a result, D50 was 13.6 μm. The powder of ZrO ₂ pulverized particles thus obtained is referred to as ZrO ₂ pulverized powder.

[Comparative Preparation Example 2]
Al ₂ O ₃ pulverized particles are obtained according to Comparative Preparation Example 1 except that an Al ₂ O ₃ fine powder raw material is used instead of the ZrO ₂ fine powder raw material. When the obtained Al ₂ O ₃ pulverized particles were observed with a scanning electron microscope (SEM), it was confirmed that they were not spherical but angular. Further, the median diameter (D50) was determined in the same manner as described above. As a result, D50 was 0.6 μm. The Al ₂ O ₃ pulverized powder thus obtained is referred to as Al ₂ O ₃ pulverized powder.

[Comparative Preparation Example 3]
AlN pulverized particles are obtained according to Comparative Preparation Example 1 except that an AlN fine powder raw material is used instead of the ZrO ₂ fine powder raw material. When the obtained AlN pulverized particles were observed with a scanning electron microscope (SEM), it was confirmed that they were not spherical but square. Further, the median diameter (D50) was determined in the same manner as described above. As a result, D50 was 0.5 μm. The powder of AlN pulverized particles thus obtained is called AlN pulverized powder.

  The reflectance of each of the spherical (granular) granulated powder and non-spherical pulverized powder obtained above was measured. The reflectance was measured as follows. After the granulated powder or pulverized powder is sufficiently placed on the slide glass so that the slide glass cannot be seen, another layer of the slide glass is placed above the granulated powder or pulverized powder layer to flatten the layer. And the upper glass slide was removed. The layer thus obtained was 15 mm in diameter and 1 mm in thickness. The reflectance of the layer was measured at intervals of 10 nm over a wavelength of 360 to 740 nm using a spectrocolorimeter “CM-2600d” (manufactured by Konica Minolta Co., Ltd.).

  Reflectivity for spherical granulated powder and non-spherical pulverized powder, and reflectivity for aluminum substrate, titanium substrate and SUS430 substrate (hereinafter referred to as “SUS substrate”) used in the following Examples and Comparative Examples Is shown in FIG. Table 1 shows the average reflectance in the near ultraviolet region and the visible light region.

In FIG. 4, the reflectance data line R11 of the ZrO ₂ granulated powder as a spherical granulated powder is marked with ■, the data line R21 of the Al ₂ O ₃ granulated powder alone is marked with ▲, and the data of the AlN granulated powder alone. The line R31 is indicated by ●, the data line R12 of the ZrO ₂ pulverized powder as a non-spherical pulverized powder is □, the data line R22 of the Al ₂ O ₃ pulverized powder is △, and the data line R32 of the AlN pulverized powder is ◯ Is shown. Further, the data line S1 of the aluminum substrate is indicated by a broken line, the data line S2 of the titanium substrate is indicated by a one-dot chain line, and the data line S3 of the SUS substrate is indicated by a two-dot chain line.

As shown in Table 1 and Figure 4, the granulated powder of ZrO ₂ is an aluminum substrate has a reflectance higher than the reflectance of the substrate at any titanium substrate, the SUS substrate, forming the Al ₂ O ₃ The grain powder has a reflectance higher than that of the substrate in the case of a titanium substrate or a SUS substrate, and has a reflectance higher than that of the substrate in the range of 360 to 420 nm in the case of an aluminum substrate. . The granulated powder of AlN has a reflectance higher than that of the substrate in the case of a titanium substrate or a SUS substrate, and has a reflectance higher than that of the substrate in the vicinity of 360 nm in the case of an aluminum substrate. Yes.

Next, the reflectance when a reflective layer is formed on each of an aluminum substrate, a titanium substrate, and a SUS substrate using the granulated powder or pulverized powder of ZrO ₂ , Al ₂ O ₃ , and AlN as a raw material will be described. In Example and Comparative Example A, an aluminum substrate is used as a base substrate, in Example and Comparative Example B, a titanium substrate is used, and in Example and Comparative Example C, a SUS substrate is used.

[Measurement of reflectance]
With respect to the reflective substrates obtained in the following examples and comparative examples, the reflectance was measured with a spectrocolorimeter “CM-2600d” (manufactured by Konica Minolta Co., Ltd.) at intervals of 10 nm over a wavelength of 360 to 740 nm. The average value in the numerical range mentioned later was calculated about the obtained measured value, and it was set as the average reflectance.

[Example and Comparative Example A: FIGS. 5A to 5C]
First, an example in which an aluminum substrate generally used for LEDs is used as a base substrate constituting the reflective substrate will be described in detail with reference to FIGS.

[Example Reflective Substrate A11]
On the aluminum substrate, a film was formed by the GD method using the spherical ZrO ₂ granulated powder obtained in Preparation Example 1 as a raw material powder. The pressure in the chamber which is a film formation chamber was adjusted to 60 Pa with a rotary pump. Nitrogen gas is used as the carrier gas, the carrier gas flow rate is 1 L / min, nitrogen gas is introduced from the nitrogen gas cylinder to the mixing part through a gas pipe as a gas introduction part, and ZrO ₂ granulated powder is converted into nitrogen in the mixing part. A powder gas dispersed in the gas was generated. The powder gas was transported to the nozzle through a powder gas transport pipe serving as a powder gas introduction section, and ZrO ₂ granulated powder was sprayed from the nozzle opening toward the aluminum substrate. A nozzle having a rectangular opening with a nozzle width of 10 mm and a nozzle slit width of 0.8 mm was employed. As the nozzle scanning method during film formation, the distance between the aluminum substrate / nozzle was 20 mm, the scanning speed was 10 mm / second, and scanning was performed for a total of 10 cycles. The above process was performed at room temperature. As described above, a reflective layer having a thickness of about 100 μm was formed on an aluminum substrate, and Example reflective substrate A11 was obtained. The thickness of the reflective layer was the same in the following examples and comparative examples, but was confirmed with a contact-type film thickness meter.

[Example Reflective Substrate A21, A31]
This was performed in the same manner as the formation of the reflective layer except that the Al ₂ O ₃ granulated powder or AlN granulated powder obtained in Preparation Examples 2 to 3 was used as the raw material powder. As a result, a reflective layer having a thickness of about 100 μm was formed on the aluminum substrate, and an example reflective substrate A21 using Al ₂ O ₃ granulated powder and an example reflective substrate A31 using AlN granulated powder were obtained, respectively. It was.

[Comparison reflective substrates A12, A22, A32]
The ZrO ₂ pulverized powder, Al ₂ O ₃ pulverized powder or AlN pulverized powder obtained in Comparative Preparation Examples 1 to 3 was used as the raw material powder. Other than that was performed like Example reflective board | substrate A11. Thereby, a reflective layer having a film thickness of about 10 to 20 μm was formed on the aluminum substrate, and comparative reflective substrates A12, A22, and A32 were obtained, respectively. Here, when a non-spherical pulverized powder was used, it was difficult to increase the film thickness, so the thickness of the reflective layer was about 10 to 20 μm.

  5A to 5C show the relationship between the wavelength and the reflectance of the aluminum substrate used as the base substrate, the example reflective substrates A11, A21, and A31 and the comparative reflective substrates A12, A22, and A32. FIG. 5A is a diagram showing the reflectance in the range of 360 to 740 nm of the example reflective substrate A11 (■), the comparative reflective substrate A12 (□), and the aluminum substrate S1 (dashed line). ) Is a diagram showing the reflectance in the range of 360 to 740 nm of the reflective substrate A21 (▲), the reflective substrate A22 (△) for comparison, and the aluminum substrate S1 (dashed line), and FIG. It is the figure which showed the reflectance of the range of 360-740 nm of reflective board | substrate A31 (-), comparative reflective board | substrate A32 ((circle)), and aluminum substrate S1 (dashed line). In FIGS. 5A to 5C, the reflectance data line of the aluminum substrate is denoted by reference numeral S1, and the reference number of the data line of each reflective substrate indicates the reflectance measurement object (implementation) for easy understanding. Example: The same reference numerals are used for the reflective substrates A11, A21, A31 and the comparative reflective substrates A12, A22, A32).

  As shown to Fig.5 (a), Example reflective board | substrate A11 has a reflectance (average reflectance 93.7%) higher than the reflectance of aluminum substrate S1 in 360-410 nm, and exceeds 410 nm. Even in the range of 740 nm or less, a high reflectance of 90% or more (average reflectance of 93.2%) is almost maintained. In addition, the reflective substrate A11 of the example has a high average reflectance of 93.6% in the range of 360 to 740 nm, and the difference between the maximum value and the minimum value of the reflectance is about 5% and is constant. Has reflectivity. On the other hand, the reflective substrate A12 for comparison has a reflectance that is 20% or more lower than that of the reflective substrate A11 of the example, which is lower than the reflectance of the pulverized powder alone (R12 in FIG. 4).

If From this, an aluminum substrate is used as the base substrate, the reflective substrate using the granulated powder particles of the ZrO ₂ spherical, higher compared to the reflection substrate using pulverized powder of non-spherical ZrO ₂ reflection Therefore, it is suitable for obtaining a constant reflectance with less wavelength dependence in the range of 360 to 740 nm. In particular, when the reflective substrate using the ZrO ₂ granulated powder is used as an LED substrate having a near-ultraviolet LED element, it has a high reflectance in the range of 360 to 740 nm, so that the amount of fluorescence due to near-ultraviolet light increases. Thus, the light extraction efficiency can be increased.

  As shown in FIG. 5B, the example reflective substrate A21 has a reflectance (average reflectance 92.8%) higher than that of the aluminum substrate S1 at 360 to 400 nm, exceeding 400 nm. Even in the range of 740 nm or less, the average reflectance is as high as 82.8%. On the other hand, the reflective substrate A22 for comparison has a maximum reflectance of 21.1%, which is 45% or more lower than that of the reflective substrate A21 of Example (average reflectance of 360 to 740 nm is 19.8%). It is lower than the reflectance of the pulverized powder alone (R22 in FIG. 4).

From this, when an aluminum substrate is used as the base substrate, the reflective substrate using the granulated powder, which is Al ₂ O ₃ spherical particles, is compared with the reflective substrate using the non-spherical pulverized powder of Al ₂ O _3. Therefore, it has a high reflectance and is suitable for obtaining a high reflectance in the range of 360 to 400 nm.

  As shown in FIG.5 (c), Example reflective board | substrate A31 has a reflectance (76.2%) higher than the reflectance of aluminum board | substrate S1 in 360 nm vicinity, In the range of 360-740 nm, it is an average. The reflectivity is 78.2%, and the difference between the maximum and minimum reflectivity is about 3%, which is a relatively high reflectivity and a constant reflectivity. On the other hand, the comparative reflective substrate A32 has a maximum reflectance of 13.8%, which is lower than that of the reflective substrate A31 in Example by 50% or more (an average reflectance of 360 to 740 nm is 13.7%). It is much lower than the reflectance of the pulverized powder alone (R32 in FIG. 4).

  Thus, when an aluminum substrate is used as the base substrate, the reflective substrate using the granulated powder, which is AlN spherical particles, has a higher reflectance than the reflective substrate using the nonspherical pulverized powder of AlN. Therefore, it is suitable for obtaining a constant reflectivity with less wavelength dependence in the range of 360 to 740 nm, as well as higher reflectivity than the aluminum substrate in the vicinity of 360 nm.

[Examples and Comparative Example B: FIGS. 6A to 6C]
Next, an example in which a titanium substrate is used as the base substrate constituting the reflective substrate will be described in detail with reference to FIGS.

[Example Reflective Substrates B11, B21, B31, Comparative Reflective Substrates B12, B22, B32]
A base substrate is a titanium substrate, and a reflective layer having a film thickness of about 100 μm is formed on the titanium substrate using ZrO ₂ , Al ₂ O ₃ , and AlN granulated powder in the same manner as in Example and Comparative Example A. Example Reflective substrates B11, B21, and B31 were obtained.

The base substrate is a titanium substrate, and a reflective layer having a film thickness of about 10 to 20 μm is formed on the titanium substrate using pulverized powder of ZrO ₂ , Al ₂ O ₃ , and AlN in the same manner as in Example and Comparative Example A. Comparative substrates for comparison B12, B22, and B32 were obtained.

  6A to 6C show the relationship between the wavelength and the reflectance of the titanium substrate S2 used as the base substrate, the example reflective substrates B11, B21, and B31 and the comparative reflective substrates B12, B22, and B32. . FIG. 6A is a diagram showing the reflectance in the range of 360 to 740 nm of the example reflective substrate B11 (■), the comparative reflective substrate B12 (□), and the titanium substrate S2 (broken line). ) Is a diagram showing the reflectance in the range of 360 to 740 nm of the reflective substrate B21 (▲), the reflective substrate B22 (△) for comparison, and the titanium substrate S2 (broken line), and FIG. It is the figure which showed the reflectance of the 360-740 nm range of reflective board | substrate B31 (-), comparative reflective board | substrate B32 ((circle)), and titanium board | substrate S2 (dashed line). In FIGS. 6A to 6C, the reflectance data line of the titanium substrate is indicated by reference numeral S2, and the reference number of the data line of each reflective substrate indicates the reflectance measurement object (implementation) for easy understanding. Example: The same reference numerals are used for the reflective substrates B11, B21, B31 and the comparative reflective substrates B12, B22, B32).

  As shown in FIG. 6A, the example reflective substrate B11 has an average reflectivity of 94.9% at 360 to 740 nm, which is higher than the reflectivity of the titanium substrate S2 (average reflectivity of 55.7%). Even in the range of 360 to 400 nm, the average reflectance is as high as 93.2%. Further, the reflective substrate B11 of the example has a constant reflectance with a difference between the maximum and minimum reflectances of about 3.4% in the range of 360 to 740 nm. On the other hand, the reflective substrate B12 for comparison has an average reflectance of 55.7%, which is 10% or more lower than that of the reflective substrate B11 of the example, and the reflection of the pulverized powder alone (R12 in FIG. 4). It is lower than the rate.

If this than was used titanium substrate as the base substrate, the reflective substrate using the granulated powder particles of the ZrO ₂ spherical, higher compared to the reflection substrate using pulverized powder of non-spherical ZrO ₂ reflection Therefore, it is suitable for obtaining a constant reflectance with less wavelength dependence in the range of 360 to 740 nm. In particular, the reflective substrate using the ZrO ₂ granulated powder has a high reflectance in the range of 360 to 740 nm when used as an LED substrate for a near ultraviolet LED element. Increase the light extraction efficiency.

  As shown in FIG. 6 (b), the example reflective substrate B21 has a reflectivity higher than that of the titanium substrate S2 at 360 to 680 nm, and the average is also in the range from 680 nm to 740 nm. The reflectance is 56.8%. On the other hand, the reflective substrate B22 for comparison has a maximum reflectance of 26.1%, which is 35% or more lower than that of the reflective substrate B21 in the above-described range (an average reflectance 20.5 at 360 to 740 nm). %), Which is lower than the reflectance of the pulverized powder alone (R22 in FIG. 4).

Compare this, in the case of using the titanium substrate as the base substrate, the reflective substrate using the granulated powder are spherical particles of Al ₂ O ₃ is a reflective substrate with a pulverized powder of non-spherical Al ₂ O ₃ Therefore, it has a high reflectance and is suitable for obtaining a high reflectance in the range of 360 to 680 nm.

  As shown in FIG. 6C, the example reflective substrate B31 has a higher reflectivity than the titanium substrate S2 in the range of 360 to 740 nm, an average reflectivity of 75.9%, and a maximum and minimum reflectivity. The difference is about 5.1%, and it has a relatively high reflectance and a constant reflectance. On the other hand, the comparative reflective substrate B32 has a maximum reflectance of 17.0%, which is lower than that of the reflective substrate B31 of Example by 50% or more (an average reflectance of 360 to 740 nm is 14.0%). It is much lower than the reflectance of the pulverized powder alone (R32 in FIG. 4).

  Thus, when a titanium substrate is used as the base substrate, the reflective substrate using the granulated powder, which is AlN spherical particles, has a higher reflectance than the reflective substrate using non-spherical pulverized powder of AlN. Therefore, it is suitable for obtaining a constant reflectance less dependent on the wavelength in the range of 360 to 740 nm as well as having a higher reflectance than the titanium substrate in the range of 360 to 740 nm.

[Examples and Comparative Example C: FIGS. 7A to 7C]
Next, an example using a SUS substrate as a base substrate for forming a reflective substrate will be described in detail with reference to FIGS.

[Example Reflective Substrates C11, C21, C31, Comparative Reflective Substrates C12, C22, C32]
The base substrate is a SUS substrate, and the reflective layer having a film thickness of about 100 μm is formed on each SUS substrate using granulated powder of ZrO ₂ , Al ₂ O ₃ , and AlN, as in the example and the comparative example A. Example Reflective substrates C11, C21, and C31 were obtained.

The base substrate is a SUS substrate, and a reflective layer having a film thickness of about 10 to 20 μm is formed on each SUS substrate using pulverized powder of ZrO ₂ , Al ₂ O ₃ , and AlN in the same manner as in Example and Comparative Example A. Comparative substrates C12, C22, and C32 for comparison were obtained.

  7A to 7C show the relationship between the wavelength and the reflectance of the SUS substrate used as the base substrate, the example reflective substrates C11, C21, and C31 and the comparative reflective substrates C12, C22, and C32. FIG. 7A is a diagram showing the reflectance in the range of 360 to 740 nm of the example reflective substrate C11 (■), the comparative reflective substrate C12 (□), and the SUS substrate S3 (broken line). ) Is a diagram showing the reflectance in the range of 360 to 740 nm of the reflective substrate C21 (▲), the reflective substrate C22 (△) for comparison, and the SUS substrate S3 (broken line), and FIG. It is the figure which showed the reflectance of the range of 360-740 nm of reflective board | substrate C31 (-), comparative reflective board | substrate C32 ((circle)), and SUS board | substrate S3 (dashed line). 7A to 7C, the reflectance data line of the SUS substrate is denoted by reference numeral S <b> 3, and the reference number of the data line of each reflective substrate indicates the reflectance measurement object (implementation) for easy understanding. Example: The same reference numerals are used for the reflective substrates C11, C21, C31 and the comparative reflective substrates C12, C22, C32).

  As shown in FIG. 7A, the reflective substrate C11 of the example has an average reflectance of 92.2% at 360 to 740 nm, which is higher than the reflectance of the SUS substrate S3 (average reflectance 48.7%). Even in the range of 360 to 400 nm, the average reflectance is as high as 92.9%. Further, the reflective substrate C11 of the example has a constant reflectance with a difference between the maximum and minimum reflectances of about 3.3% in the range of 360 to 740 nm. On the other hand, the reflective substrate C12 for comparison has an average reflectance of 47.6%, which is 30% or more lower than that of the reflective substrate C11 of the example, and the reflection of the pulverized powder alone (R12 in FIG. 4). It is lower than the rate.

If this than was used SUS substrate as the base substrate, the reflective substrate using the granulated powder particles of the ZrO ₂ spherical, higher compared to the reflection substrate using pulverized powder of non-spherical ZrO ₂ reflection It is suitable for obtaining a constant reflectance with less wavelength dependence in the range of 360 to 740 nm as well as higher reflectance than the SUS substrate at 360 to 400 nm. In particular, the reflective substrate using the ZrO ₂ granulated powder has a high reflectance in the range of 360 to 740 nm when used as an LED substrate for a near ultraviolet LED element. Increase the light extraction efficiency.

  As shown in FIG. 7B, the example reflective substrate C21 has a reflectance (average reflectance 65.1%) higher than that of the SUS substrate S3 at 360 to 580 nm. On the other hand, the comparative reflective substrate C22 has an average reflectance of 18.5% in the above-mentioned range, and is a reflectance that is 30% or lower lower than that of the reflective substrate C21 of Example. R22) is lower than the reflectance.

Compare this, when using a SUS substrate as the base substrate, the reflective substrate using the granulated powder are spherical particles of Al ₂ O ₃ is a reflective substrate with a pulverized powder of non-spherical Al ₂ O ₃ Therefore, it has a high reflectance and is suitable for obtaining a high reflectance in the range of 360 to 580 nm.

  As shown in FIG.7 (c), Example reflective board | substrate C31 has a reflectance higher than SUS board | substrate S3 in the range of 360-460 nm, and an average reflectance is 44.5%. In addition, the reflective substrate C31 of Example has a constant reflectance with a difference between the maximum and minimum reflectances of about 2.0% in the range of 360 to 740 nm. On the other hand, the reflective substrate for comparison C32 has a maximum reflectance of 15.9%, which is 20% or more lower than that of the reflective substrate C31 of the example (average reflectance of 360 to 460 nm: 14.5%, 360 to 360%). The average reflectance at 740 nm is 14.8%), which is much lower than the reflectance of the pulverized powder alone (R32 in FIG. 4).

  Thus, when a SUS substrate is used as the base substrate, the reflective substrate using the granulated powder, which is AlN spherical particles, has a higher reflectance than the reflective substrate using the nonspherical pulverized powder of AlN. Therefore, it is suitable for obtaining a constant reflectance less dependent on the wavelength in the range of 360 to 740 nm, while obtaining a higher reflectance than the SUS substrate in the range of 360 to 460 nm.

  In the above example, the reason why the reflectance was greatly improved in the near-ultraviolet region was that the use of spherical inorganic particles enabled the formation of a low-density reflective layer on the base substrate containing many voids inside. It is estimated that.

  As described above, by using spherical inorganic particles and forming a reflective layer on the base substrate by a powder spray coating method, compared with non-spherical inorganic particles without performing a high-temperature heat treatment step such as firing. And high reflectivity can be obtained. Thereby, a base substrate, a wiring metal, etc. weak to a heat treatment process can be used.

  In particular, in at least a part of the wavelength range of 360 nm or more and 400 nm or less, the reflectance of the spherical inorganic particles is higher than that of the base substrate. In a device using near-ultraviolet light, the reflection efficiency can be increased.

  DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus, 10 ... Powder tank, 20 ... Film-forming chamber, 30 ... Vacuum pump, 40 ... Gas introduction part, 50 ... Powder gas introduction part, 60 ... Exhaust pipe, 70 ... Raw material powder, 80 ... Injection nozzle, 90 ... movable stage, 100 ... target substrate, 110 ... mixing unit, 120 ... gas cylinder

Claims (8)

  A method for producing a reflective substrate, comprising using a spherical inorganic particle to form a reflective layer in at least a partial region on a base substrate by a powder spray coating method.   2. The method for producing a reflective substrate according to claim 1, wherein 70% or more (on a number basis) of the spherical inorganic particles are particles having a particle diameter in a range of 20 to 60 μm.   The method for producing a reflective substrate according to claim 1, wherein the spherical inorganic particles are spherical granulated powder obtained by a spray drying method. The method for manufacturing a reflective substrate according to claim 1, wherein the spherical inorganic particles are particles containing at least one selected from ZrO ₂ , SiO ₂ , Al ₂ O _3, and AlN.   The method for manufacturing a reflective substrate according to any one of claims 1 to 4, wherein a material of a reflective layer forming region in the base substrate is aluminum, titanium, or stainless steel.   The method for manufacturing a reflective substrate according to claim 1, wherein the thickness of the reflective layer is in a range of 1 μm or more. A base substrate;
A reflective layer formed in at least a partial region on the base substrate by a powder spray coating method using spherical inorganic particles;
A reflective substrate.   The reflective board | substrate of Claim 7 which is a board | substrate for LED element mounting.