JP5478404B2 - Manufacturing method of alumina ceramic - Google Patents

Description

The present invention relates to a method for producing an alumina ceramic, and more particularly to a method for producing an alumina ceramic containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase that is less likely to have voids therein.

  Ceramic packages are used as packages (substrates) for housing light-emitting elements such as high-intensity light-emitting diodes (LEDs) and semiconductor lasers (LDs). Such a package includes a base body on which the light emitting element is mounted and a frame body provided on the base body and having a through hole. And a light emitting element is accommodated in the through-hole of a frame, and is arrange | positioned on a base | substrate. The base is provided with a power distribution conductor for energizing from the outside, and the light emitting element is electrically connected to the power distribution conductor by a bonding wire. The light emitting element emits light when it is energized from the outside through the power distribution conductor and the bonding wire, and the light emitted from the light emitting element is directly emitted to the outside or reflected on the surface of the base or the inner peripheral surface of the frame. And released to the outside. Accordingly, the shape and composition of the surface of the substrate and the inner peripheral surface of the frame greatly affect the light emission efficiency of the light emitting device.

  As a frame of the light emitting device as described above, a frame made of a metal having a high reflectance is known. However, such a frame body has a coefficient of thermal expansion different from that of a ceramic substrate, and may be peeled off from the substrate by heat generated from the light emitting element. Therefore, in the frame body of Patent Document 1 below, in order to prevent such peeling between the substrate and the frame body, metal plating is applied to the ceramic frame body. In this frame, silver (Ag) is used as a plating material, and the reflectance of light having a wavelength of about 460 nm is about 90% of the reflectance of barium sulfate. However, this frame has a low reflectance of light having a wavelength of about 460 nm or less, and an average reflectance of 77% in the wavelength range of 250 nm to 800 nm.

Therefore, Patent Document 2 listed below describes an alumina ceramic excellent in light reflectivity and a manufacturing method thereof. This alumina ceramic is an alumina ceramic containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase, and is obtained by firing a material containing at least a mixed material of a barium compound, alumina, and silica. According to this alumina ceramic, it is said that a reflectance exceeding 90% can be realized at a wavelength of 300 nm or more.

Japanese Patent Laid-Open No. 2004-228531 International Publication No. 2010/001760

  However, the alumina ceramic described in Patent Document 2 has excellent reflection characteristics, but when a material containing a mixed material of a barium compound, alumina, and silica is fired, a gas resulting from the barium compound is generated. For this reason, an unintended void is generated in the manufactured alumina ceramic, and the warp of the alumina ceramic and the bending strength may be reduced, which may result in failure to obtain the alumina ceramic as designed.

Accordingly, the present invention is, internal void hardly occurs _in, and an object thereof is to provide a method for producing an alumina ceramic containing a Ba _0.808 Al _{1.71 Si 2.29} O ₈ phase.

The method for producing an alumina ceramic of the present invention includes a first firing step of firing a frit containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase, and crushing the frit to obtain Ba _0.808 Al. _1.71 Si _2.29 O ₈ pulverized powder containing alumina ceramic particles containing a phase, mixing at least the frit powder, alumina containing alumina powder, silica containing silica powder And a mixing step of forming a mixed material, a forming step of forming the mixed material, and a second firing step of sintering the formed mixed material.

According to such an alumina ceramic manufacturing method, the frit containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase is once fired in the first firing step. At this time, gas due to the barium compound is generated, and voids or the like may be generated in the frit. However, since the frit is pulverized in the pulverization step after the first firing step, It doesn't matter. Then, in the mixing step, alumina powder and silica powder are mixed with the frit powder obtained by pulverizing the frit, and then molded in the molding step. In the second firing step, the molded mixed material is fired to obtain an alumina ceramic. Further, in the second baking step, since the gas due to the barium compound has already been generated in the first baking step, generation of new gas can be suppressed. Therefore, it is possible to obtain an alumina ceramic having a desired porosity by suppressing the generation of voids in the second firing step. Thus, since it can suppress that a void arises, the alumina ceramic by which the fall of the warp and bending strength was suppressed can be obtained. Moreover, since the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase is formed in the obtained alumina ceramic, it can have excellent reflection characteristics.

In the method for producing an alumina ceramic, in the first firing step, the mixed material containing at least alumina, silica, and a barium compound is fired, and the mixed material used in the first firing step includes: When the compounding ratio by the weight parts of the alumina, the silica, and the barium compound is calculated by converting the weight parts of the barium compound by BaO,
4/96 <(BaO + SiO ₂ ) / (Al ₂ O ₃ ) <24/76
It is preferable that

Furthermore, in the alumina ceramic, the mixing molar ratio of the silica and the barium compound (in terms of BaO) in the mixed material used in the first firing step is:
BaO / SiO ₂ = 8/1 to 8/32
It is preferable that

  In the alumina ceramic, the barium compound is preferably barium carbonate.

  According to such a method for producing an alumina ceramic, it can be produced at a relatively low cost while having high reflection characteristics.

As described above, according to the present invention, there is provided a method for producing an alumina ceramic containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase, in which voids are not easily generated.

It is sectional drawing which shows the light emitting element mounting substrate which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the manufacturing method of an alumina ceramic and a light emitting element mounting substrate. FIG. 3 is a diagram showing the reflectance of Example 1 and Comparative Example 1 at each wavelength.

  Hereinafter, preferred embodiments of an alumina ceramic according to the present invention and a light-emitting element mounting substrate using the same will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a light emitting element mounting substrate according to an embodiment of the present invention.

  As shown in FIG. 1, the light emitting element mounting substrate 1 includes a base 11 and a frame 12 formed on the base 11. The base 11 is formed in a plate shape. The frame body 12 on the base 11 is formed in a cylindrical shape, and an opening 13 is formed. The outer peripheral surface of the frame 12 is formed substantially perpendicular to one surface of the base 11, and the inner peripheral surface is inclined with respect to the one surface of the base 11. The peripheral surface is formed so as to face the side opposite to the base 11 side, that is, the opening 13 side. The base 11 and the frame 12 are made of alumina ceramic and are integrally molded.

  In the light emitting device using the light emitting element mounting substrate 1, the light emitting elements are arranged on the base 11 in the opening 13 of the light emitting element mounting substrate 1, and the light emitting elements are placed on the base 11. It is connected to a wiring (not shown) provided by a bonding wire.

In this alumina ceramic, alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing the phase containing Ba are dispersed. Therefore, in this alumina ceramic, as a whole, alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing the phase containing Ba are adjacent to each other. The interface by each particle is formed.

The average particle size of these alumina ceramic particles is preferably 1.5 μm to 3.5 μm from the viewpoint of obtaining stable light reflection characteristics, and more preferably 1.5 μm to 2.0 μm. The alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase have a particle size distribution in which 30% or more of the particles are within a range of ± 1.5 μm of the average particle size. It is preferable from the viewpoint of obtaining high strength, and it is more preferable that 50% or more of the particles have a particle size distribution that is within a range of ± 1.0 μm of the average particle size.

  In addition, the measurement of the above-mentioned alumina ceramic particles was performed according to the following procedure using particle analysis software A Image-kun (registered trademark) manufactured by Asahi Chemical Engineering Co., Ltd. First, the cut surface of the alumina ceramic of the present invention is mirror-polished using an appropriate apparatus. Then, carbon is vapor-deposited on the polished cut surface, and the crystal structure is photographed with a scanning electron microscope (SEM). The photographing magnification at this time is 2,000 times, and the number of pixels is 960 pixels in the vertical direction and 1280 pixels in the horizontal direction. The image was analyzed with the above particle analysis software, and the crystal diameter was determined. A plurality of the crystal diameters were measured and averaged to obtain an average particle diameter.

Moreover, this alumina ceramic has a molar ratio of barium to silica in the whole ceramic,
Ba / Si = 8/1 to 8/32
It is preferable from the viewpoint that it can have more excellent reflection characteristics with respect to light having a wavelength of 300 to 400 nm. Furthermore, the molar ratio of barium to silica in the entire ceramic is
Ba / Si = 8/3 to 8/32
It is more preferable from the viewpoint that it can have more excellent reflection characteristics with respect to light having a wavelength of 300 to 400 nm.

Furthermore, the ceramic has a molar ratio of barium to silica in alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase.
Ba / Si = 10/15 to 10/27
It is preferable from the viewpoint that it can have more excellent reflection characteristics, and further Ba / Si = 10/18 to 10/24.
It is preferable from the viewpoint that it is possible to have more excellent reflection characteristics.

In the light of wavelength 589 nm, alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing the phase containing Ba dispersed throughout the ceramic in this way. A refractive index difference of 0.1 to 0.3 is preferable from the viewpoint of providing an appropriate refractive index difference at the interface between the respective particles and having excellent reflection characteristics with respect to light having a wavelength of 300 nm to 400 nm.

As described above, according to the alumina ceramic of the present embodiment, excellent light reflection characteristics can be obtained. In such an alumina ceramic, alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing the phase containing Ba are dispersed, and Ba ₀ It is known that alumina ceramic particles containing _.808 Al _1.71 Si _2.29 O ₈ phase have a higher refractive index than alumina ceramic particles not containing a phase containing Ba. Therefore, the alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase having a high refractive index and the alumina ceramic particles not containing a phase containing Ba having a low refractive index are dispersed. Overall, an interface is formed in which particles having a high refractive index and particles having a lower refractive index than these particles are adjacent to each other. In this way, at the interface where the difference in refractive index between adjacent particles is large, the reflection of light is large, so that it can have excellent light reflection characteristics.

  Next, the manufacturing method of such an alumina ceramic and the light emitting element mounting substrate 1 will be described.

FIG. 2 is a flowchart showing a procedure of a manufacturing method of the alumina ceramic and the light emitting element mounting substrate 1. As shown in FIG. 2, the manufacturing method of the light emitting element mounting substrate 1 is a preparation step P1, Ba _0.808 in which raw material powders containing a barium compound, alumina, and silica are prepared, and these raw material powders are mixed and then molded. A first firing step P2 for firing a frit containing an Al _1.71 Si _2.29 O ₈ phase, and this frit is pulverized to contain a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase. A pulverization step P3 for producing a frit powder containing alumina ceramic particles, a mixing step P4 for mixing at least a frit powder, an alumina powder containing alumina, and a silica powder containing silica to obtain a mixed material, and a mixed material And a second firing step P6 for sintering the molded mixed material as main steps.

(Preparation process P1)
First, a barium compound, alumina, and silica are prepared, and the prepared barium compound, alumina, and silica are powdered and mixed.

  Note that barium compound, alumina, and silica may be charged into a ball mill or the like during mixing, and the respective barium compound, alumina, and silica may be mixed while being pulverized and powdered. At this time, a dispersing agent, a plasticizer, or a dye may be added to a ball mill or the like together with each material. In this way, a mixed material of barium compound powder, alumina powder, and silica powder is obtained.

  Although it does not specifically limit as a material of a barium compound, Barium hydride, barium fluoride, barium hydroxide, barium oxide, barium chloride, barium carbonate, barium sulfate, barium nitrate etc. can be mentioned, especially barium oxide, carbonic acid Barium is preferable, and barium carbonate is particularly preferable from the viewpoint of high raw material purity and low price. In addition, the average particle diameter of the barium compound powder in a state where the barium compound powder, the alumina powder, and the silica powder are mixed is 1.0 to 2.0 μm, so that the barium compound powder can be sufficiently dispersed. To preferred.

  The average particle size of the alumina powder in a state where the barium compound powder, the alumina powder, and the silica powder are mixed is 5 μm or less, so that a frit that is more uniformly sintered can be obtained by the first sintering step P2. It is preferable from the viewpoint. In addition, considering the light reflection performance of the alumina ceramic after production, flexibility, sinterability at the time of production, etc., the average particle size of the alumina powder in the state where the barium compound powder, alumina powder, and silica powder are mixed is Particularly preferably, the thickness is 0.1 μm to 3 μm.

  Moreover, in alumina powder, in order to adjust the above-mentioned light reflection performance, flexibility, and sinterability, alumina powder having different average particle diameters can be mixed and used. For example, the combination of particle sizes of two types of alumina powders having different average particle sizes is not particularly limited, but 3 μm and 0.2 μm, 3 μm and 0.3 μm, 3 μm and 0.4 μm, 3 μm and 0.5 μm, and 3 μm. And 0.6 μm, 2 μm and 0.2 μm, 2 μm and 0.3 μm, 2 μm and 0.4 μm, 2 μm and 0.5 μm, 2 μm and 0.6 μm, and the like. Further, the combination is not limited to two kinds of alumina powders having different average particle diameters, and three or more kinds of alumina powders having different average particle diameters may be combined. When two types of alumina having different average particle diameters are used, the blending ratio by weight parts of (large particle diameter alumina powder) / (small particle diameter alumina powder) is 100/1 to 60/40. preferable. In particular, in order to obtain excellent light reflection performance, flexibility, and sinterability by mixing alumina powders having different average particle diameters, (alumina powder having a large particle diameter) / (alumina having a small particle diameter) The blending ratio by weight parts of the powder is preferably 85/15 to 65/35, more preferably 80/20 to 70/30.

  In addition, the average particle diameter of the silica powder in a state where the barium compound powder, the alumina powder, and the silica powder are mixed is preferably 1 μm or less from the viewpoint of reducing the hygroscopicity of the alumina ceramic after the production, More preferably, it is -0.7 micrometer, and it is further more preferable that it is 0.3-0.6 micrometer.

Moreover, the compounding ratio by the weight part of the alumina, silica, and barium compound in the state where the barium compound powder, the alumina powder, and the silica powder are mixed is, when the weight part of the barium compound is converted by BaO,
4/96 <(BaO + SiO ₂ ) / (Al ₂ O ₃ ) <24/76
It is preferable that By mixing in this way, it can be set as the alumina ceramic which can have high board | substrate intensity | strength, having a high reflective characteristic.

Moreover, the compounding molar ratio of the barium compound (in terms of BaO) and silica (SiO ₂ ) in a state where the barium compound powder, the alumina powder, and the silica powder are mixed,
BaO / SiO ₂ = 8/1 to 8/32
It is preferable that By mixing in this way, it can be set as the alumina ceramic which can suppress the hygroscopic property of a board | substrate, having a high reflective characteristic.

  Next, a mixed material in which barium compound powder, alumina powder, and silica powder are mixed is formed. In molding, the mixed material may be molded by a powder molding method or a green sheet method.

  In the case of molding by the powder forming method, a mixed material of barium compound powder, alumina powder, and silica powder is molded densely by a molded body such as a mold. Specifically, a mixed material of a barium compound powder, alumina powder, and silica powder, a binder, a lubricant, and a solvent are mixed to form a slurry. Then, the slurry-like mixed material is granulated using a spray dryer or the like. At this time, the diameter of the granulated particles is preferably 25 μm to 200 μm, and more preferably 30 μm to 15 μm. In addition, after granulation, it is preferable to classify the granulated particles using a sieve or the like. This is to improve the filling property of the particles into the molded body and to suppress the occurrence of burrs and the like by entering the clearance of the molded body.

  Although it does not restrict | limit especially as a binder used at this time, For example, an acrylic type, PVA (polyvinyl alcohol) type etc. can be mentioned. Moreover, it is preferable that it is 0.5 mass%-5.0 mass%, and, as for content of binder resin with respect to solid content of a slurry, it is more preferable that it is 1.5 mass%-3.5 mass%.

  Further, the lubricant is not particularly limited, and for example, a stearic acid emulsion can be exemplified, and the content in the solid content is preferably 0.05% by mass to 0.5% by mass, and 0.1% by mass. It is further more preferable that it is% -0.3 mass%.

  Moreover, it does not specifically limit as a solvent, However When using a solvent as mentioned above, water can be mentioned. The amount of the solvent is not particularly limited, but is preferably 20% by mass to 80% by mass, for example, 40% by mass to 60% by mass with respect to the total amount of barium compound powder, alumina powder, and silica powder. Is more preferable.

Further, when the granulated particles are densely molded by a molded body such as a mold, the granulated particles are filled in the mold and molded by applying pressure at room temperature. In this case, pressure applied to the granulated particles ^is preferably from ^{0.5t / cm 2 ~2.0t / cm 2} , and further preferably from ^{0.7t / cm 2 ~1.5t / cm 2} .

  In this way, a material in which the molded barium compound powder, alumina powder, and silica powder are mixed is obtained.

  In the case of molding by the green sheet method, a slurry is obtained by adding and kneading a solvent, a binder resin, a dispersant, a plasticizer and the like to a mixed material of barium compound powder, alumina powder, and silica powder.

  Examples of the binder resin include acrylic and PVB (polyvinyl butyral) binder resins. Further, the content of the binder resin with respect to the solid content of the slurry is preferably 4.0% by mass to 20% by mass, and more preferably 6.0% by mass to 8.0% by mass.

  Moreover, as a dispersing agent, surfactant can be used, 0.1 mass%-1.0 mass% are preferable, and, as for the content rate with respect to solid content, 0.3 mass%-0.5 mass% More preferably, it is mass%.

  Moreover, as a plasticizer, DOP (Dioctyl Phthalate), DBP (Dibutyl Phthalate) etc. can be used, for example, It is preferable that content in solid content is 3.0 mass%-15 mass%. It is more preferable that it is 4.0 mass-6.0 mass%.

  As a solvent, alcohol, toluene, etc. can be used, for example, and it is preferable that solid content becomes 70 mass%-80 mass%. The viscosity of the slurry is preferably 3,000 cps to 30,000 cps, and more preferably 10,000 cps to 20,000 cps.

  Next, the obtained slurry is poured into a film coated with a release agent, and the solvent is evaporated by drying. At this time, the drying temperature is preferably 80 to 130 ° C, more preferably 100 to 120 ° C. Moreover, it is preferable that a drying rate shall be 0.2 m / min-2.0 m / min.

  Then, a green sheet is produced | generated by peeling a film. This green sheet is punched into a desired shape with a press molding machine to obtain a material in which the molded barium compound powder, alumina powder, and silica powder are mixed.

(First firing step P2)
Next, the mixed material of the barium compound powder, alumina powder, and silica powder is fired. The firing temperature at this time is preferably 1400 ° C. to 1600 ° C. from the viewpoint of obtaining a frit sufficiently containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase. More preferably. Thus, the frit containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase is fired.

(Crushing process P3)
Next, the obtained frit is pulverized. In the pulverization, the obtained frit can be pulverized by an appropriate method, for example, about 2 mm square, and then charged into a ball mill together with a solvent, and further pulverized. In this case, the frit is pulverized by a ball mill to form a frit powder, and then the frit powder is taken out together with the solvent and dried to remove the solvent. In this way, a frit powder is obtained.

(Mixing process P4)
Next, alumina powder and silica powder are prepared, and at least the frit powder obtained previously, alumina powder, and silica powder are mixed to obtain a mixed material. In the mixing step P4, the respective powders having a desired particle diameter in the pulverizing step P3 may be prepared and mixed. At this time, you may mix a dispersing agent, a plasticizer, dye, etc. with each powder.

  Note that at least one part of the pulverization step P3 and at least one part of the mixing step P4 may be performed simultaneously. That is, the frit pulverized to each appropriate size, alumina, and silica may be charged into, for example, a ball mill and mixed while pulverizing each material. At this time, when the dispersant, the plasticizer, and the dye are mixed together with the respective materials, the dispersant, the plasticizer, and the dye may be added to the ball mill together with the respective materials.

  The average particle size of the frit powder in a state where the frit powder, the alumina powder and the silica powder are mixed is preferably 2.0 μm to 3.0 μm from the viewpoint of obtaining an alumina ceramic having higher reflection characteristics. Therefore, when the frit, alumina, and silica are mixed while being pulverized as described above, the particle size of the prepared frit is set to be larger than the above particle size. On the other hand, when each powder having a desired particle size is prepared and mixed without further pulverization, in the pulverization step P3, the frit powder is pulverized so as to have the above particle size. To do.

  Moreover, what is necessary is just to use the alumina similar to the alumina used in the above-mentioned preparatory process P1. And the particle diameter of the alumina powder in the state where each powder was mixed may be the same as that of the alumina powder in the state where barium compound powder, alumina powder and silica powder are mixed in the preparation step P1.

  Moreover, what is necessary is just to use the silica similar to the silica used in the above-mentioned preparatory process P1. And the particle diameter of the silica powder in the state in which each powder is mixed may be the same as that in the state in which the barium compound powder, alumina powder, and silica powder are mixed in the preparation step P1.

In addition, the blending ratio by weight parts of alumina, silica, and barium compound after mixing frit powder, alumina powder, and silica powder is as follows when the weight part of barium compound is converted to BaO:
4/96 <(BaO + SiO ₂ ) / (Al ₂ O ₃ ) <24/76
It is preferable that By mixing in this way, it is possible to obtain an alumina ceramic that has higher reflection characteristics and can maintain high substrate strength.

Further, the barium compound in a state where each of the powders are mixed (BaO equivalent) and the blending molar ratio of silica (SiO _2),
BaO / SiO ₂ = 8/1 to 8/32
It is preferable that By mixing in this way, it is possible to obtain an alumina ceramic that has higher reflection characteristics and can suppress the hygroscopicity of the substrate.

  Furthermore, in order to produce an alumina ceramic excellent in the reflectance of light having a wavelength of 300 to 400 nm, the frit is adjusted so that the molar ratio of Ba and Si in the sintered alumina ceramic is 8/1 to 8/32. It is preferable to mix | blend powder and a silica powder, and it is more preferable to set it as 8 / 3-8 / 32.

(Molding process P5)
Next, a material in which frit powder, alumina powder, and silica powder are mixed is formed. In the molding, the light emitting element mounting substrate 1 shown in FIG. For example, the light emitting element mounting substrate 1 is formed into a shape in which a plurality of prototypes are connected.

  In this molding, the material mixed with the powder may be molded by a powder forming method in which the material mixed with the frit powder, alumina powder, and silica powder is densely molded into a molded body such as a mold. In this case, the frit powder, alumina powder, silica powder, binder, lubricant and solvent are mixed to form a slurry. Then, the slurry material is granulated using a spray dryer or the like. At this time, the diameter of the granulated particles is preferably 25 μm to 200 μm, and more preferably 30 μm to 15 μm. In addition, after granulation, it is preferable to classify the obtained granulated particles for the same reason and means as the classification of the granulated particles in the preparation step P1.

  Further, the binder used at this time is not particularly limited, but the same amount of the same binder as in the preparation step P1 may be used. The lubricant is not particularly limited, but the same amount of the same lubricant as in the preparation step P1 is used. The solvent may be used, and the solvent is not particularly limited, but the same amount of the solvent as in the preparation step P1 may be used.

  Further, when the material mixed with the granulated frit powder, alumina powder, and silica powder is densely formed by a molded body such as a mold, the barium compound powder, alumina powder, and silica powder are mixed in the preparation step P1. What is necessary is just to carry out like the dense material.

  Thus, a mixed material of the formed frit powder, alumina powder, and silica powder is obtained.

(Second firing step P6)
Next, the mixed material of the formed frit powder, alumina powder, and silica powder is fired. The firing temperature at this time is lower than the first firing temperature, preferably 1450 ° C. to 1600 ° C., and more preferably 1520 ° C. to 1590 ° C.

  Thus, an alumina ceramic including the light emitting element mounting substrate 1 shown in FIG. 1 is obtained.

  Next, unnecessary portions of the obtained alumina ceramic are shaved or divided into a plurality of light emitting element mounting substrates 1. In this way, the light emitting element mounting substrate 1 shown in FIG. 1 is obtained.

As described above, according to the method for producing an alumina ceramic of the present embodiment, the frit containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase is once fired in the first firing step P2. . At this time, gas due to the barium compound is generated, and voids or the like may be generated in the frit. However, since the frit is pulverized in the pulverization step P3 after the first firing step P2, voids and the like are generated. It doesn't matter. Then, in the mixing step P4, alumina powder and silica powder are mixed with the frit powder obtained by pulverizing the frit, molded in the molding step P5, and in the second firing step P6, the molded mixed material is fired to obtain an alumina ceramic. obtain. In the second firing step P6, since the gas due to the barium compound has already been generated in the first firing step P2, the generation of new gas can be suppressed. Therefore, in the second firing step P6, it is possible to suppress the generation of voids and unnecessary porous portions, and to obtain an alumina ceramic having a desired porosity. Therefore, it is possible to obtain an alumina ceramic in which warpage and bending strength are suppressed.

Further, in the second firing step P6, since the mixed material mixed with the frit powder containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase is fired, the barium compound powder and the alumina powder are conventionally used. And the firing temperature can be made lower than the case where the mixed powder in which the silica powder is mixed is fired to obtain an alumina ceramic containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase. On the other hand, the 1st baking process P2 is made the same with the baking temperature of said conventional alumina ceramic, and generally requires the expensive high temperature furnace. However, in the first firing step P2, a high-temperature furnace having the same scale as that for producing the conventional alumina ceramic is used to fire the same amount of frit as that of the conventional alumina ceramic. Higher amounts of alumina ceramic can be produced. In other words, when producing the same amount of alumina ceramic as in the prior art, it can be a high-temperature furnace with a small scale, and alumina containing Ba _0.808 Al _1.71 Si _2.29 O ₈ phase at low cost. Ceramic can be produced.

Further, by this alumina ceramic manufacturing method, alumina ceramic particles containing Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing a phase containing Ba are dispersed. A ceramic can be obtained, and according to such an alumina ceramic, excellent light reflection characteristics can be obtained as described above.

  As mentioned above, although this invention was demonstrated to the example for embodiment, this invention is not limited to these.

  For example, in the above embodiment, in the molding step P5, a material in which frit powder, alumina powder, and silica powder are mixed is molded so as to include the prototype of the light emitting element mounting substrate 1 shown in FIG. When alumina ceramic is not used as the light emitting element mounting substrate 1, it may be molded into another shape. For example, in the forming step P5, a material in which frit powder, alumina powder, and silica powder are mixed can be formed into a sheet shape. In the case of forming the material and the sheet in this way, the material mixed with the barium compound powder, the alumina powder, and the silica powder in the preparation step P1 may be formed in the same manner as the sheet is formed.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Example 1>
First, 31.0 parts by weight (52.7 kg) of high-purity barium carbonate (product name: LSR, manufactured by Nippon Chemical Industry Co., Ltd.) and low soda alumina (product name: HQ-C, Sumitomo Chemical) 48.0 parts by weight (81.6 kg) and 21.0 parts by weight (35.7 kg) of synthetic spherical silica (product name: Admafine SO-C2, manufactured by Admatechs) were prepared. . Next, barium carbonate, low soda alumina, and synthetic spherical silica were charged into a 200-liter alumina liner ball mill. At this time, 0.4 parts by weight (0.68 kg) of sorbitan sesquioleate (product name: Sorgen 30, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 5.0 parts by weight of a plasticizer (DOP) as a dispersant together with the above materials Part (8.5 kg), 0.02 part by weight (0.035 kg) of dye (product name: Aminyl Blue E-2GL, manufactured by Taoka Chemical Co., Ltd.), and mixed organic solvent (toluene 50% by weight) , 33.2 parts by weight (56.5 kg) of ethanol was added. And it mixed for 24 hours at 26 rotations per minute.

  Next, 10.0 parts by weight (17.0 kg) of polyvinyl butyral (product name: a mixture of S-REC BL-S and BM-SZ, manufactured by Sekisui Chemical Co., Ltd.) is added and further rotated at 26 rpm for 24 hours. Mixing to give a blue suspension.

  The obtained suspension was applied by the doctor blade method to produce a plurality of green sheets for frits having a width of 30 cm, a length of 1 m, and a thickness of about 0.34 mm. The green sheets thus obtained were rolled into a roll shape, arranged in an alumina mortar without gaps, and placed in a firing furnace (apparatus name: HST-30-17F, manufactured by Chugai Prox). Frit was obtained by firing in air for a minute.

  Next, the obtained frit was roughly pulverized to about 2 mm square using an appropriate tool, and 0.4446 kg was put into an alumina pot mill having a capacity of 2 liters. Further, 0.2966 kg of mixed organic solvent (50% by weight of toluene and 50% by weight of ethanol) was added as a solvent (solid content 60%), and mixed and ground for 96 hours at 50 rpm. Thereafter, the contents were put into a stainless steel vat to dry the solvent, and the frit powder was recovered. The recovered frit powder was measured with a particle size distribution analyzer (manufactured by Nikkiso Co., Ltd .: Microtrac MT-3000), and D50 was 2.6 μm.

  Next, 25.5 parts by weight (240.0 g) of the previously obtained frit powder and 73.8 parts by weight (693.5 g) of low soda alumina (product name: HQ-C, manufactured by Sumitomo Chemical Co., Ltd.) Then, 0.6 parts by weight (6.0 g) of synthetic spherical silica (product name: Admafine SO-C2, manufactured by Admatex Co., Ltd.) was prepared, and charged into an alumina pot mill having a capacity of 2 liters. At this time, 0.4 parts by weight (3.8 g) of sorbitan sesquioleate (product name: Sorgen 30, manufactured by Daiichi Kogyo Kagaku Co., Ltd.) and 2.5 parts by weight of plasticizer (DOP) (23. 23) as dispersants. 5 g), 0.020 parts by weight (0.2 g) of a dye (product name: Aminyl Blue E-2GL, manufactured by Taoka Chemical Co., Ltd.), and a mixed organic solvent (toluene 50% by weight, ethanol 50% by weight) %) Was charged at 31.0 parts by weight (291.0 g). And it mixed for 24 hours at 50 rpm.

  Next, 5.0 parts by weight (47.0 g) of polyvinyl butyral (a product name: a mixture of ESREC BL-S and BM-SZ, manufactured by Sekisui Chemical Co., Ltd.) was added. The mixture was further mixed for 24 hours at 50 revolutions per minute to obtain a blue suspension.

  Next, the obtained suspension was taken out into a 2 liter disc and stirred and defoamed at 0.04 MPa for 10 minutes. The viscosity after defoaming was 15,000 cps when measured using a B-type viscometer under the conditions of rotor number 4, rotor rotational speed 6 rpm, and temperature 4 ° C.

  Next, the defoamed suspension was applied by a doctor blade method to obtain a green sheet. At this time, the gap between the doctor blade and the carrier film is 0.850 mm, the line speed is 0.1 m / min, the drying temperature is 50 ° C. in the first zone, the second zone is 100 ° C., and the air volume is 4. 0 m / sec, the second zone was 5.6 m / sec. The coated green sheet was carefully peeled off from the carrier film, cut to a length of about 240 mm, and collected. When the thickness at the top of the green sheet was measured, it was about 880 μm. No abnormalities such as coating streaks and bubbles were observed on the green sheet surface.

  Next, the thickness of the obtained green sheet was measured, and a green sheet having a thickness in the range of 640 μm to 760 μm was cut out. And the cut-out green sheet was shape | molded with the press. At the time of molding, the outer punching dimensions were 72 mm in length and 84 mm in width.

Next, the formed green sheets are stacked on an alumina shelf board in a stack of three so that the dry surface and the carrier surface are alternately stacked, and a firing furnace (product name: HST-30-17F, manufactured by Chugai Prox Co., Ltd.) ) And baked in the atmosphere at 1580 ° C. for 40 minutes. Thus, the alumina ceramic of Example 1 was obtained. In this alumina ceramic, the blending ratio by weight parts of alumina, silica, and barium is Al ₂ O ₃ : SiO ₂ : BaO = 85.7%: 4.1% when the weight part of barium is converted to BaO: 10.2%.

<Comparative Example 1>
First, 8.0 parts by weight (80.0 g) of high-purity barium carbonate (product name: LSR, manufactured by Nippon Chemical Industry Co., Ltd.) was prepared. Then, a high-purity barium carbonate and a mixed organic solvent (toluene 50% by weight, ethanol 50% by weight) as a solvent together with 13.8 parts by weight (138.2 g) are charged into a 2 liter alumina pot mill. For 10 hours at 50 rpm.

  Next, 68.8 parts by weight (688.2 g) of low soda alumina (product name: HQ-C, manufactured by Sumitomo Chemical Co., Ltd.) and 17 of fine particle alumina (product name: AES-12, manufactured by Sumitomo Chemical Co., Ltd.) are used. .2 parts by weight (171.8 g) and 6.0 parts by weight (60.0 g) of synthetic spherical silica (product name: Admafine SO-C2, manufactured by Admatechs Co., Ltd.) were prepared. Then, together with the prepared low soda alumina, fine particle alumina, and synthetic spherical silica, 0.4 part by weight (4.0 g) of sorbitan sesquioleate (product name: Sorgen 30, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersant. ) And 5.0 parts by weight (50.0 g) of bis (2-ethylhexanoic acid) triethylene glycol (product name: G-260, manufactured by Sumitomo Chemical Co., Ltd.) as a plasticizer, and a dye (product name: Aminyl) Blue E-2GL, manufactured by Taoka Chemical Co., Ltd., 0.020 parts by weight (0.2 g), and a mixed organic solvent (toluene 50% by weight, ethanol 50% by weight) as a solvent, 20.7 parts by weight (207 4 g) The mixture was put into a pot mill and mixed at 50 rpm for 15 hours.

  Next, 9.0 parts by weight (90.0 g) of polyvinyl butyral (a product name: a mixture of ESREC BL-S and BM-SZ, both manufactured by Sekisui Chemical Co., Ltd.) is charged at 50 rpm. Further mixing for 24 hours gave a blue suspension.

  The obtained suspension was taken out into a 2 liter disc and stirred and degassed at 0.04 MPa for 10 minutes. The viscosity after defoaming was measured using a B-type viscometer under the conditions of rotor number 4, rotor rotational speed 6 rpm, and slurry temperature 11 ° C., and was 20,500 cps.

  Next, the defoamed suspension was applied by a doctor blade method to obtain a green sheet. At this time, the gap between the doctor blade and the carrier film is 1.200 mm, the line speed is 0.1 m / min, the drying temperature is 50 ° C. in the first zone, the second zone is 100 ° C., and the air volume is 4.0 m in the first zone. / Second, the second zone was 5.6 m / second. Then, the coated green sheet was carefully peeled off from the carrier film, cut to a length of about 240 mm, and collected. When the thickness of the head of this green sheet was measured, it was about 970 μm. No abnormalities such as coating streaks and bubbles were observed on the surface of the green sheet.

Next, the obtained green sheet was molded in the same manner as in Example 1. And the green sheet was baked like Example 1 except a calcination temperature being 1615 degreeC. Thus, an alumina ceramic of Comparative Example 1 was obtained. In this alumina ceramic, the compounding ratio by weight parts of alumina, silica, and barium is the same as in Example 1 when the weight part of barium is converted to BaO, and Al ₂ O ₃ : SiO ₂ : BaO = 85. 7%: 4.1%: 10.2%.

<Water absorption measurement>
The water absorption measurement was performed according to the following procedure according to the procedure defined as the water absorption test of JIS C2141 (2002), which is a ceramic material test for electrical insulation.

First, the alumina ceramics of Example 1 and Comparative Example 1 were dried in a thermostatic bath set at 110 ° C., and when they reached a constant weight, they were removed from the thermostatic bath, placed in a desiccator and returned to room temperature, and then the mass was measured with a balance. Weigh and dry weight m ₁ .

  Next, the dried and constant weight alumina ceramic is put in a metal container containing water and boiled for 30 minutes. At this time, the amount of water is sufficient to sufficiently immerse the alumina ceramic. Further, an appropriate jig is used so that the alumina ceramic is positioned about 1 cm above the bottom of the metal container.

Then removed alumina ceramic from the water, after wiping water droplets quickly surface with a damp gauze, weighed mass, and the mass m ₂ of water-saturated test substrate.

The water absorption rate (%) is obtained by calculating {(m ₂ −m ₁ ) / m ₁ } × 100.

  As a result, the water absorption of the alumina ceramic of Example 1 is 0.001%, and the water absorption of the alumina ceramic of Comparative Example 1 is 0.004%. There was no significant difference in water absorption.

<Reflectance evaluation>
The reflectance of the alumina ceramic obtained in Example 1 and Comparative Example 1 was measured. For the measurement of reflectance, a spectrophotometer U-4000 manufactured by Hitachi, Ltd. was used, and the reflectance for light in the wavelength region of 250 nm to 800 nm was measured. At this time, the measurement conditions were a band pass of 5 nm and a scan speed of 300 nm / min.

  The result is shown in FIG. FIG. 3 is a diagram showing the reflectance of Example 1 and Comparative Example 1 at each wavelength. In FIG. 3, the numerical value indicating the reflectance indicates a relative value when the reflectance of a standard white plate made of barium sulfate is 100. As shown in FIG. 3, although the alumina ceramic of Example 1 and the alumina ceramic of Comparative Example 1 do not change much in water absorption as described above, the alumina ceramic of Example 1 is the alumina of Comparative Example 1. Compared with ceramics, it showed high reflectance in all measured wavelength regions.

<Bending strength measurement>
The measurement was performed using a 3-point bending indicator with a desktop material testing machine STA-1225 manufactured by Orientec. The measurement conditions were a test speed of 0.5 mm / min, a load full scale of 50 N, and a fulcrum distance of 30 mm.

  As a result, the bending strength of Example 1 is 303.5 MPa, the bending strength of Comparative Example 1 is 284.1 MPa, and the alumina ceramic of Example 1 and the alumina ceramic of Comparative Example 1 are as described above. Although the water absorption rate did not change so much, it was found that the alumina ceramic of Example 1 had a higher bending strength than the alumina ceramic of Comparative Example 1. This is considered to be because in the alumina ceramic of Comparative Example 1, voids that affect the bending strength are generated by the gas generated during firing.

<Measurement of sled>
The warpage of the alumina ceramics of Example 1 and Comparative Example 1 was measured using a measuring device (trade name: E-RC-S01B) manufactured by Tokyo Seimitsu Co., Ltd. As the measurement site, a vertical warp at 7 mm from each of the left and right ends, an upper end in the vertical direction of the alumina ceramic, and a horizontal warp at 7 mm from the lower end were measured on the front side and the back side of the alumina ceramic. The results are shown in Table 1.

  As shown in Table 1, it was found that the alumina ceramic of Example 1 has a smaller warp than the alumina ceramic of Comparative Example 1, and has an external shape close to the design value.

As mentioned above, according to the alumina ceramic of this invention, it has confirmed that a reflectance was higher than the conventional alumina ceramic. This is because the alumina ceramic particles of Example 1 are generally composed of alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase and alumina ceramic particles not containing the phase containing Ba. It is thought that it is because it is doing. Further, it was confirmed that the alumina ceramic of Example 1 had a high bending strength and a small warp. This is considered to be because the production of the alumina ceramic of Example 1 can suppress the occurrence of unintended voids inside.

According to the present invention, the internal voids are unlikely to occur in the _method of alumina ceramics containing Ba _0.808 Al _{1.71 Si 2.29} O ₈ phase is provided.

DESCRIPTION OF SYMBOLS 1 ... Light emitting element mounting substrate 11 ... Base 12 ... Frame 13 ... Opening P1 ... Preparatory process P2 ... Firing process P3 ... Grinding process P4 ... Mixing process P5 ... Molding process P6 ... Firing process

Claims (2)

Firing a material mixed with barium compound powder, alumina powder, and silica powder to obtain a frit containing a Ba _0.808 Al _1.71 Si _2.29 O ₈ phase;
Crushing the frit into a frit powder comprising alumina ceramic particles containing the Ba _0.808 Al _1.71 Si _2.29 O ₈ phase;
A mixing step of mixing at least the frit powder, an alumina powder containing alumina, and a silica powder containing silica;
A molding step of molding the mixed material;
A second firing step of sintering the molded mixed material;
A method for producing an alumina ceramic, comprising: The method for producing an alumina ceramic according to claim 1, wherein the barium compound is barium carbonate.

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