JP4654577B2 - Ceramic substrate for mounting photoelectric conversion elements - Google Patents

Description

  The present invention relates to a ceramic substrate for mounting a photoelectric conversion element on which a photoelectric conversion element such as an LED is mounted.

  Conventionally, photoelectric conversion elements such as light-emitting diodes (LEDs) have been used for applications such as electronic device indicators, but in recent years their luminous efficiency and luminance have improved, and the luminance per unit input has been incandescent. LEDs that are superior to lamps have been developed, and by combining a plurality of LEDs, it has become possible to apply them to lighting applications.

  Also, since LEDs have a long service life, they have merit of maintenance such as labor saving of lamp replacement, and illumination that does not emit infrared rays that damage fresh food due to a narrow emission wavelength range (for example, show in a fish shop) For example), and can be used for lighting that does not emit ultraviolet light that causes deterioration of the work of art (eg, museum lighting).

  In addition, photoelectric conversion elements such as LEDs are also used in optical exchanges, optical interconnection devices, and the like, and contribute to realization of a large communication capacity and high speed.

Such a photoelectric conversion element is often used by being mounted on a substrate in order to be coupled with electric wiring. As a substrate for mounting a photoelectric conversion element, as disclosed in Patent Document 1, for example, it is proposed to use a ceramic substrate made of alumina, aluminum nitride, silicon carbide, beryllium oxide, or the like.
JP 2000-357770 A

  When the ceramic substrate as described above is mounted with a photoelectric conversion element, if a material that absorbs light emitted from the photoelectric conversion element is used, the light emitted from the photoelectric conversion element mounted on the substrate is actually observed. The light emission brightness is reduced. In addition, it is necessary to provide a conductor wiring made of a metal or the like for connecting the photoelectric conversion element and the electric wiring on the ceramic substrate. For this reason, it is necessary to provide excellent adhesion strength between the ceramic substrate and the metal film. is there.

  However, it has been difficult to impart high adhesion between the ceramic substrate and the metal, and there has been no conventional one that has also imparted high light reflectivity to the ceramic substrate.

  The present invention has been made in view of the above points, and improves the light emission efficiency by reflecting the light emitted from the photoelectric conversion element with high efficiency while ensuring sufficient adhesion strength with the conductor wiring. An object of the present invention is to provide a ceramic substrate for mounting a photoelectric conversion element.

A ceramic substrate 1 for mounting a photoelectric conversion element according to the present invention is a ceramic substrate 1 for mounting a photoelectric conversion element for mounting a photoelectric conversion element that emits light, and is formed by molding and firing a ceramic powder, alumina, containing silica and magnesia, and silica content of 0.1 to 1% by weight with alumina as a main component, magnesia content Ri 0.01% by mass, and silica, magnesia and alumina the content of components other than is characterized by having 2 wt% or less der Ru high reflectivity phase 2. As a result, the high reflectivity phase 2 has high light reflectivity, and when a metal film is formed on the surface, it has a high peel strength with the metal film, and has good fluidity during molding. And has high moldability.

It is preferable that the average particle size of alumina powder before Symbol ceramic powder is in the range of 0.3～1Myuemu. In this case, further improvement in moldability and smoothing of the surface can be achieved.

It is also preferred that the average particle size of the silica powder before Symbol ceramic powder is made to be 1μm or less. In this case, surface smoothing and strength improvement can be achieved.

  Further, it is preferable to form a cover phase having a silica content smaller than that of the high reflectance phase 2 outside the high reflectance phase 2. In this case, the peel strength when the conductor wiring is formed on the ceramic substrate 1 is improved, and the light is reflected at a high reflectance at the interface between the cover phase and the high reflectance phase 2, so that the ceramic substrate 1 as a whole is sufficient. Light reflectance can be ensured.

  The cover phase is preferably formed by subjecting a layer having the same composition as that of the high reflectivity phase 2 to a chemical treatment to elute silica. In this case, a thin film cover phase can be easily formed.

  ADVANTAGE OF THE INVENTION According to this invention, the ceramic substrate for photoelectric conversion element mounting which can reflect the light emitted from a photoelectric conversion element with high efficiency, and can improve luminous efficiency, ensuring sufficient adhesive strength between conductor wiring. Can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The ceramic substrate 1 according to the present invention has a high reflectivity phase 2 containing 0.1 to 1% by mass of silica and 0.01 to 0.5% by mass of magnesia, with the balance being made of alumina. The ceramic substrate 1 may be formed only from the high reflectance phase 2 or may be formed by integrating the ceramic phase having another composition and the high reflectance phase 2. The shape of the high reflectivity phase 2 is not particularly limited.

  The high reflectivity phase 2 can be formed by molding ceramic powder. As the ceramic powder, a ceramic powder having a desired high reflectance phase 2 composition can be used. That is, alumina powder, magnesia powder, and silica powder are used as the ceramic powder. The amount of silica powder used is 0.1 to 1% by mass in the total ceramic powder, and the amount of magnesia powder used is 0.01 to It can be made 0.5 mass%.

  FIG. 3 schematically shows an example of the manufacturing process of the ceramic substrate 1 using the ceramic powder.

  When the high reflectance phase 2 is formed using ceramic powder, for example, the ceramic powder and an appropriate binder are mixed with a kneader 6 such as a heating kneader (see FIG. 3A), and the obtained molding is obtained. The high reflectivity phase 2 can be formed by forming the material into a desired shape, heating and degreasing the material, and firing the material. The composition of the binder is not particularly limited, and it is possible to appropriately select and use one that can form the molding material and can be decomposed and volatilized by heat degreasing. For example, polystyrene 60% by mass, paraffin wax What has a composition of 20 mass% and stearic acid 20 mass% can be used.

  Moreover, although the usage-amount of a binder is also adjusted suitably, it is preferable to make a binder into the range of 15-25 mass parts with respect to 100 mass parts of ceramic powder.

  The molding material is prepared by mixing alumina powder, magnesia powder, silica powder, and a binder. At this time, alumina powder, magnesia powder, and silica powder may be premixed and then mixed with the binder. However, the magnesia powder and silica powder are very small, and the particle size is small and the specific surface area is large. It becomes difficult to mix uniformly. For this reason, preferably, alumina powder, magnesia powder, silica powder and a binder are blended and mixed at the same time. In this case, the binder serves as a dispersing agent, and the dispersibility of a minute amount of fine powder components is improved. A homogeneous molding material can be obtained. At this time, for example, when using a raw material containing two kinds of components in advance among alumina, magnesia, and silica, such as alumina powder containing pre-magnesia (manufactured by Sumitomo Chemical Co., Ltd., “AES-11”, etc.) A ceramic powder containing two kinds of components, the remaining powder, and a binder are mixed at the same time.

  The high reflectivity phase 2 can be formed by an appropriate technique using the molding material as described above, but it is preferable to apply CIM (ceramic injection molding). In this case, the pelletized molding material obtained by mixing the ceramic powder and the binder as described above is injected into a molding die 8 using an injection unit 7 of an injection molding machine, and injection molding is performed. It shape | molds in the molded article 9 of a shape (refer FIG.3 (b)).

  Next, the obtained molded product 9 is heated and degreased (see FIG. 3C). In the illustrated example, the molded product 9 is arranged on the arrangement table 11 (setter), and the arrangement table 11 is stacked in multiple stages, and this is arranged in the degreasing furnace 10 and degreased by heating.

  Next, the molded product 9 after heat degreasing is fired and sintered to obtain the ceramic substrate 1 (see FIG. 3D). In the illustrated example, the molded product 9 after heat degreasing is heated and fired in the sintering furnace 15 in a state where the molded product 9 is placed in multiple stages on the arrangement table 11.

  The ceramic substrate 1 provided with such a high reflectivity phase 2 has a high light reflectivity in the high reflectivity phase 2 and a high peel strength with the metal film when a metal film is formed on the surface. In addition, it has good flowability during molding and high moldability.

  Here, when the silica content in the high reflectance phase 2 is less than the above range (that is, when the amount of silica powder in the ceramic powder is less than the above range), the light reflectance of the high reflectance phase 2 is high. When the silica content exceeds the above range (that is, when the amount of silica powder used in the ceramic powder exceeds the above range), the surface of the high reflectivity phase 2 is made of metal. When a film is formed, sufficient peel strength cannot be obtained (see Example 5 and FIG. 5).

  When the magnesia content in the high reflectivity phase 2 is less than the above range (that is, when the amount of magnesia powder in the ceramic powder is less than the above range), a metal film is formed on the surface of the high reflectivity phase 2. When sufficient peel strength is not obtained, and the magnesia content in the high reflectance phase 2 exceeds the above range (that is, when the amount of magnesia powder used in the ceramic powder exceeds the above range), The viscosity of the molding material is increased, the fluidity is lowered, and the moldability is lowered. In particular, sufficient moldability cannot be obtained at the time of injection molding when CIM is applied (Example 6 and FIG. 6). reference).

  The high reflectivity phase 2 is mainly composed of alumina and contains silica and magnesia. However, the inclusion of other components is not prohibited. For example, inevitable impurities are mixed. Permissible. At this time, the content of components other than silica, magnesia and alumina in the high reflectivity phase 2 is preferably 2% by mass or less.

  In addition, it is preferable that the alumina powder in the ceramic powder in the molding material has an average particle size in the range of 0.3 to 1 μm. In this case, further improvement of moldability and smoothing of the surface And can be achieved. If the average particle size of the alumina powder is less than 0.3 μm, the specific surface area becomes too large, leading to an increase in the viscosity of the molding material, resulting in a decrease in fluidity and a decrease in moldability. If the average particle size exceeds 1 μm, sintering at high temperature is required for sintering, which leads to a decrease in productivity and equipment for high-temperature sintering, The surface roughness of the molded body obtained after firing becomes large, and it becomes difficult to form fine conductor wiring 14 on the surface, and the void density between the particles becomes large because the voids between the internal particles become large. In addition, there is a risk of lowering the strength (see Example 7 and FIG. 7).

  The silica powder in the ceramic powder in the molding material preferably has an average particle size of 1 μm or less. In this case, surface smoothing and strength improvement can be achieved. If the average particle diameter of the silica powder exceeds 1 μm, voids generated by melting of the silica powder during firing increase, resulting in an increase in surface roughness and an increase in internal voids, which may lead to a decrease in strength. (See Example 8 and FIG. 8). The lower limit of the average particle diameter of the silica powder is not particularly limited, but is preferably 0.3 μm or more in order to ensure good fluidity of the molding material at the time of molding by CIM.

  In the ceramic substrate 1 formed in this way, it is preferable to form a recess 4 for mounting an element as shown in FIGS. If such a recessed part 4 is formed, when the photoelectric conversion element 3 mounted on the ceramic substrate 1 emits light, the inner surface of the recessed part 4 serves as a reflector, and the photoelectric conversion efficiency is improved. That is, as shown in FIG. 1B, the photoelectric conversion element 3 may be mounted on the ceramic substrate 1 in which the recess 4 is not provided. In this case, light emitted from the photoelectric conversion element 3 is diffused to the surroundings. As a result, sufficient luminance may not be obtained. On the other hand, as shown in FIG. 1A, if the concave portion 4 for element mounting is provided in the ceramic substrate 1 and the photoelectric conversion element 3 is mounted in the concave portion 4, the photoelectric conversion element 3 can be removed. Of the emitted light L, the light L emitted laterally is reflected by the inner surface of the recess 4, and the light emission luminance can be improved by aligning the direction of light emission from the photoelectric conversion element 3. At this time, the inner surface of the concave portion 4 is preferably formed so as to incline downward from the outer edge side of the concave portion 4, and the photoelectric conversion element 3 is preferably disposed at the bottom portion of the concave portion 4. The light L emitted laterally from the photoelectric conversion element 3 is reflected by the inclined surface of the recess 4, and the reflected light is emitted toward the opening direction of the recess 4, so that the light L emitted from the photoelectric conversion element 3. The light emission luminance can be improved by aligning the directions of.

  The ceramic substrate 1 for mounting a photoelectric conversion element is provided with a core phase 5 containing alumina and having a lower silica content than the high reflectivity phase 2 with respect to the high reflectivity phase 2 having the above composition. Can be formed. At this time, the high reflectivity phase 2 is provided so as to cover a part or all of the core phase 5. FIG. 2 shows an example of the ceramic substrate 1 provided with the high reflectivity phase 2 and the core phase 5. In the illustrated example, a recess 4 for mounting an element is formed on one surface of the high reflectivity phase 2. The core phase 5 is embedded in the high reflectivity phase 2 so that the core phase 5 is covered with the high reflectivity phase 2, and the core phase 5 is exposed on the other surface of the high reflectivity phase 2. It has become. The core phase 5 is formed so as to be disposed inside the recess 4 for mounting the element. Thereby, the surface on which the conductor wiring 14 is formed and the surface on which the photoelectric conversion element 3 is mounted are formed in the high reflectivity phase 2, and the core phase 5 is disposed on the inside thereof.

  In this way, ensuring the light reflectance and maintaining the peel strength of the conductor wiring 14 are maintained in the high reflectance phase 2. Further, since the core phase 5 has a low silica content and a high purity of alumina, the thermal conductivity is larger than that of the high reflectivity phase 2, and heat generated from the photoelectric conversion element 3 mounted on the ceramic substrate 1 is dissipated. This improves the heat radiation characteristics.

  The core phase 5 may be any material as long as it contains alumina and has a silica content smaller than that of the high reflectivity phase 2 as described above, but preferably the silica content is 0.2% by mass or less. More preferably, it is formed so as not to contain silica. Moreover, magnesia can be contained as components other than the alumina and silica of the core phase 5, and the content thereof is preferably in the range of 0.01 to 0.5% by mass.

  In order to form the ceramic substrate 1 having such a high reflectivity phase 2 and the core phase 5, it is preferable to apply an appropriate two-color molding method such as two-color injection molding. That is, using a two-color injection molding machine, for example, a molding material for forming the high reflectivity phase 2 is first injected, and then a molding material for forming the core phase 5 is injected.

  In addition, it is conceivable to form only the core phase 5 by firing and then form the high reflectivity phase 2 by insert molding or the like. In this case, however, cracks occur at the interface between the core phase 5 and the high reflectivity phase 2. May occur. For this reason, it is preferable that the high reflectance phase 2 and the core phase 5 are fired and sintered simultaneously by performing two-color molding as described above, thereby preventing the occurrence of cracks.

  Further, the ceramic substrate 1 for mounting a photoelectric conversion element is formed by providing a cover phase containing alumina and having a lower silica content than the high reflectance phase 2 outside the high reflectance phase 2 having the above composition. You can also That is, for example, the cover phase is formed so as to cover one surface outside the high reflectivity phase 2 where the conductor wiring 14 is formed (one surface where the element mounting recess 4 is formed). Further, a cover phase may be formed so as to cover the entire surface of the high reflectivity phase 2.

  In this way, the silica content on the surface of the ceramic substrate 1 that is in close contact with the conductor wiring 14 is reduced, so that the peel strength of the conductor wiring 14 is improved. Here, the cover phase itself with a reduced silica content has a light reflectivity that is lower than the high reflectivity, but the light is reflected at a high reflectivity at the interface between the cover phase and the high reflectivity phase 2. Therefore, the ceramic substrate 1 as a whole can secure a sufficient light reflectance.

  The cover phase only needs to contain alumina and have a silica content lower than that of the high reflectivity phase 2 as described above, and is preferably formed so as not to contain silica. Moreover, magnesia can be contained as components other than the alumina and silica of the cover phase, and the content is preferably in the range of 0.01 to 0.5 mass%. Further, the thickness of the cover phase is not particularly limited.

  In order to form the ceramic substrate 1 having such a high reflectance phase 2 and a cover phase, an appropriate two-color molding method such as two-color injection molding can be applied. More preferably, after molding a molded body having the same composition as the high reflectivity phase 2, a cover phase is formed by elution of silica by applying a chemical treatment to the outer layer, and the inside of the cover phase. A portion not subjected to the chemical treatment is formed as the high reflectance phase 2. When such chemical treatment is performed, the cover phase can be easily formed, and the cover phase can be easily formed into a thin film.

  As the chemical used in the chemical treatment, any suitable chemical can be used as long as it can elute silica. For example, an aqueous sodium hydroxide solution can be used. In this case, a molded body having the same composition as that of the high reflectance phase 2 is immersed in an aqueous sodium hydroxide solution and the outer layer thereof is subjected to a chemical treatment, thereby forming a cover phase and a high reflectance inside the cover phase. Phase 2 is formed.

  In forming the conductor wiring 14 on the ceramic substrate 1 formed in this manner, an appropriate method can be adopted.

  A preferred example of a method for forming the conductor wiring 14 is shown in FIG. First, a conductive thin film 12 made of copper or the like is formed on the surface of the ceramic substrate 1, and the conductive thin film 12 is partially removed by irradiating the conductive thin film 12 with an electromagnetic wave such as a laser beam. At this time, the region 13 surrounded by the portion from which the conductor thin film 12 has been removed is made to have a desired conductor pattern (see FIG. 4A).

  Next, the conductor pattern 14 is formed by thickening the conductor pattern-shaped portion by electrolytic plating. At this time, the conductive thin film 12 which is not thickened remains (see FIG. 4B).

  Since the remaining conductive thin film 12 is electrically insulated from the conductor wiring 14, it may be left as it is, or may be removed by performing a soft etching process (FIG. 4 ( c)).

  When forming the conductor wiring 14 as described above, it is preferable to clean the surface of the ceramic substrate 1 by performing a heat treatment in advance when forming the conductor thin film 12. In order to improve the adhesion between the conductor wiring 14 and the ceramic substrate 1, it is also preferable to perform a surface treatment such as a plasma treatment in advance. The conductor thin film 12 can be formed by adopting an appropriate method, but can be formed by DC magnetron sputtering using, for example, copper or the like as a target. At this time, the thickness of the conductor thin film 12 is desirably formed in the range of 100 to 1000 nm.

  Moreover, in the partial removal of the conductor thin film 12 by electromagnetic waves, for example, a third harmonic of a YAG laser (THG-YAG laser) can be used.

  Moreover, at the time of formation of the conductor wiring 14 by electrolytic plating, for example, electrolytic copper plating can be performed to form the copper conductor wiring 14. Moreover, it is preferable that the thickness of this conductor wiring 14 is the range of 5-20 micrometers.

[Example 1]
The following materials were put into a heating kneader so as to have a mass ratio of powder raw material: binder = 100: 20 and kneaded to prepare pellets.

Powder raw material composition-Alumina powder (containing 0.1% by weight of magnesia, manufactured by Sumitomo Chemical Co., Ltd., "AES-11", average particle size φ0.5 µm) ... 99.5 parts by mass-Silica powder (manufactured by Admatech, "SO- C2 ”, particle size 0.4 to 0.6 μm)... 0.5 part by mass Here, the alumina powder“ AES-11 ”contains 0.1% by mass of magnesia. Contains 0.0995% by mass of magnesia.

Binder composition ・ Polystyrene… 60% by mass
・ Paraffin wax: 20% by mass
・ Stearic acid: 20% by mass.

By using the above pellets and injection molding under the conditions of a material temperature of 180 ° C., a mold temperature of 20 ° C., and an injection rate of 40 cm ³ / s on an injection molding machine (manufactured by FANUC, “ROBOSHOT-α50iAp”), 40 mm × A rectangular flat plate shaped product 9 having a size of 30 mm × 2 mm was obtained.

  The molded product 9 was degreased by heating from room temperature to 550 ° C. over 72 hours, and then heated and sintered at 1600 ° C. for 1 hour.

(Viscosity measurement)
The fluidity of the molding material was measured using a flow tester (manufactured by Shimadzu Corporation, “CFT-500D”). At this time, when the die shape is 1 mm in diameter and 1 mm in length, and the amount of pressurization is 0.98 MPa, the measured value at 180 ° C. is 0.1 ml / s or more, and the less than that Rated as bad.

(Reflectance measurement)
The ceramic substrate 1 obtained by sintering was measured for reflectance with respect to light having a wavelength of 470 nm using an ultraviolet / visible spectrophotometer (manufactured by Shimadzu Corporation, “UV3100PC”).

(Surface roughness)
About the ceramic substrate 1 obtained by sintering, the arithmetic average roughness (Ra) was measured using the non-contact three-dimensional measuring machine (the product made by Mitaka Kogyo, "NH-3N").

(density)
About the ceramic substrate 1 obtained by sintering, using an electronic balance, the dry mass, the mass in water, and the mass of the saturated test piece are measured in accordance with JIS C2141. Based on this, the apparent density and the bulk density are determined. Was calculated.

(Thermal conductivity)
About the ceramic substrate 1 obtained by sintering, a test piece having a diameter of 10 mm was cut out from this, and the thermal conductivity of the test piece was measured according to JIS R1611 using a thermal constant measuring device (“TC-3000” manufactured by Vacuum Riko). The measurement was performed in accordance with the laser flash method.

(Peel strength)
The ceramic substrate 1 obtained by sintering was heated at 1000 ° C. for 1 hour to clean the surface, then the surface was subjected to plasma treatment, and a conductive thin film was formed using a DC magnetron sputtering apparatus. That is, first, the ceramic substrate 1 obtained by sintering was set in a chamber of a plasma processing apparatus, the inside of the chamber was depressurized to about 10 ⁻⁴ Pa, and then preheated at 150 ° C. for 3 minutes. Thereafter, oxygen gas is circulated in the chamber, the gas pressure in the chamber is controlled to about 10 Pa, and in this state, a 1 kW high-frequency voltage (RF: 13.56 MHz) is applied between the electrodes to generate plasma. For 300 seconds to perform plasma treatment. Next, the pressure in the chamber is set to 10 ⁻⁴ Pa or less, and after introducing argon gas into the chamber to a gas pressure of 0.6 Pa in this state, a DC voltage of 500 V is further applied to bombard the copper target. Thus, a conductive thin film 12 made of copper having a thickness of 500 nm was formed.

  Next, using a third harmonic of a YAG laser (THG-YAG laser) in the atmosphere, with an average output of 6 W, a spot diameter of 40 μm, and a scanning speed of 200 mm / s, the laser is linearly spaced on the sintered body surface at intervals of 5 mm. Scanned.

  Thus, after forming the pattern by a laser, the electrolytic copper plating process was performed and the conductor wiring 14 which consists of a 15-micrometer-thick copper film was formed.

  A peel strength test (90 degree peel test) was performed on the conductor wiring 14 formed on the ceramic substrate 1 in this manner. At this time, using a universal material testing machine (manufactured by Shimadzu Corp., “Autograph AG10TD”), the test is performed at a constant speed of 50 mm / s under a room temperature / atmospheric pressure atmosphere, and the unit is based on JIS C6481 The peel strength per width (90 degree peel strength) was calculated.

[Example 2]
As a silica powder, “SO-C5” (particle size: 1.3 to 2.0 μm) manufactured by Admatech Co., Ltd. was used.

  Other than that was carried out similarly to Example 1, and produced the sample and the evaluation test (except heat conductivity measurement).

Example 3
A molding material for forming the core phase 5 was prepared using only “AES-11” manufactured by Sumitomo Chemical Co., Ltd., which is a magnesia-containing alumina powder, as a powder raw material.

  The molding material for forming the high reflectivity phase 2 was the same as that of Example 1.

Then, using an injection molding machine (manufactured by FANUC, “ROBOSHOT-α50iAp”), two-color injection molding is performed under the conditions of a material temperature of 180 ° C., a mold temperature of 20 ° C., and an injection rate of 40 cm ³ / s, 40 mm × 30 mm A rectangular flat plate-shaped body having a size of 2 mm was obtained. This molded body was formed in a form in which the core phase 5 having a volume ratio of about 1/2 was embedded in the high reflectivity phase 2.

  The molded body was degreased by heating from room temperature to 550 ° C. over 72 hours, and then sintered by heating at 1600 ° C. for 1 hour.

  About the obtained sample, the same evaluation test as Example 1 was implemented.

Example 4
A sample formed by the same method as in Example 1 was subjected to a chemical treatment that was immersed in an aqueous solution of sodium hydroxide having a concentration of 20% and a temperature of 30 ° C. for 30 minutes to elute the surface silica to form a cover phase.

  About the obtained sample, the same evaluation test (except heat conductivity measurement) as Example 1 was implemented.

[Comparative Example 1]
A molding material was prepared using only “AES-11” manufactured by Sumitomo Chemical Co., Ltd., which is a magnesia-containing alumina powder, as a powder raw material.

  Other than that was carried out similarly to Example 1, and produced the sample and the evaluation test (except heat conductivity measurement).

[Comparative Example 2]
The powder raw material composition was changed as follows.

・ Alumina powder (containing 0.1% by weight of magnesia, manufactured by Sumitomo Chemical Co., Ltd., “AES-11”, average particle size φ0.5 μm) ... 98 parts by mass ・ Silica powder (manufactured by Admatech, “SO-C2”, particle size) 0.4 to 0.6 μm)... 2 parts by mass Except that, sample preparation and evaluation tests (excluding thermal conductivity measurement) were performed in the same manner as in Example 1.

[Comparative Example 3]
A molding material was prepared using only “AES-12” (average particle diameter φ0.5 μm) manufactured by Sumitomo Chemical Co., Ltd., which is an alumina powder containing no magnesia as a powder raw material.

  Other than that was carried out similarly to Example 1, and produced the sample and the evaluation test (except heat conductivity measurement).

[Comparative Example 4]
The powder raw material composition was changed as follows.

Alumina powder (manufactured by Sumitomo Chemical Co., Ltd., “AES-12”, average particle diameter φ0.5 μm) 99 parts by mass Magnesia powder (manufactured by Tateho Chemical Co., “# 500”) 1 part by mass Other than that, Example 1 In the same manner, sample preparation and evaluation tests (excluding thermal conductivity measurement) were performed.

  The results are shown in Table 1.

Example 5
As ceramic materials, alumina powder (containing 0.1% by mass of magnesia, manufactured by Sumitomo Chemical Co., Ltd., “AES-11”, average particle diameter φ0.5 μm) and silica powder (manufactured by Admatech Co., “SO-C2”, particle size of 0. 4 to 0.6 μm), the amount of silica powder used was changed, and the other conditions were changed in the same manner as in Example 1 to change the silica content in the sample.

  About the obtained sample, the result of having performed peel strength measurement and reflectance measurement is shown in FIG. As shown in this result, the reflectance rapidly decreases when the silica content is less than 0.1% by mass, and the peel strength increases rapidly when the silica content becomes 1% by mass or less. In order to obtain reflectance and peel strength, it was confirmed that the silica content should be in the range of 0.1 to 1.0 mass%.

Example 6
Alumina powder (manufactured by Sumitomo Chemical Co., Ltd., “AES-12”, average particle size φ0.5 μm) and silica powder (manufactured by Admatech, “SO-C2”, particle size 0.4-0.6 μm) and magnesia as ceramic raw materials Using powder (manufactured by Tateho Chemical Co., “# 500”), the silica content was fixed at 0.5 mass%, the magnesia content was varied, and other conditions were the same as in Example 1. The magnesia content in the sample was changed.

  The results of measuring the fluidity of the molding material and the peel strength of the sample are shown in FIG. As shown in this result, the peel strength decreases rapidly when the magnesia content is less than 0.01% by mass, and the viscosity measurement result (flow value) decreases as the magnesia content increases. In order to achieve 1 ml / s or more, the magnesia content had to be 0.5% by mass or more. That is, it was confirmed that the magnesia content should be in the range of 0.01 to 0.5% by mass in order to ensure high peel strength and good fluidity (moldability).

Example 7
Alumina powder (manufactured by Sumitomo Chemical Co., Ltd., “AES-12”, average particle diameter φ0.5 μm) and magnesia powder (manufactured by Tateho Chemical Co., “# 500”) as a ceramic raw material, and various silicas with different average particle diameters The powder was used so that the silica content was 0.5% by mass and the magnesia content was 0.1% by mass. The particle size was changed.

  FIG. 7 shows the results of measuring the fluidity of the molding material and the bulk density of the sample. As shown in this result, good fluidity (formability) is obtained when the average particle diameter of alumina is 0.3 μm or more, but when this average particle diameter increases, the bulk density decreases and the amount of voids in the sample increases. In order to maintain good moldability and prevent an increase in void volume and a decrease in strength and an increase in surface roughness, the average particle diameter of alumina should be in the range of 0.3 to 1 μm. It was confirmed that it was preferable.

Example 8
While using alumina powder (containing 0.1% by weight of magnesia, “AES-11”, average particle diameter φ0.5 μm) as a ceramic raw material, various silica powders with varying average particle diameters were used, The silica content was 0.5% by mass, and the other conditions were the same as in Example 1, and the average particle size of the silica particles used for preparing the sample was varied.

  About the obtained sample, the result of having measured arithmetic mean roughness Ra is shown in FIG. As the result, the larger the particle size of the silica powder, the larger the surface roughness. In order to obtain a smooth ceramic substrate 1, the average particle size of the silica powder is preferably 1 μm or less. ,confirmed.

The ceramic substrate which concerns on this invention is shown, (a) (b) is sectional drawing. It is sectional drawing which shows the other example of the ceramic substrate which concerns on this invention. It is a schematic sectional drawing which shows the manufacturing process of the ceramic substrate which concerns on this invention. An example of the manufacturing process of the conductor wiring in the ceramic substrate which concerns on this invention is shown, (a) to (c) is the fracture | ruptured perspective view which concerns on this invention. It is a graph which shows the test result of Example 5, a horizontal axis is a silica content in a ceramic substrate, a left vertical axis is a measurement result of light reflectance of this ceramic substrate, and a right vertical axis is this ceramic substrate and The peel strength between the conductor wires is shown. It is a graph which shows the test result of Example 6, a horizontal axis | shaft is magnesia content in a ceramic substrate, a left vertical axis | shaft is the flow volume measured at the time of a viscosity measurement, and a right vertical axis | shaft is this ceramic substrate, conductor wiring, Each peel strength is shown. It is a graph which shows the test result of Example 7, a horizontal axis is an average particle diameter of the alumina powder used in order to produce a ceramic substrate, a left vertical axis is a flow amount measured at the time of viscosity measurement, and a vertical axis on the right side. Each axis indicates the measurement result of the bulk density of the produced ceramic substrate. It is a graph which shows the test result of Example 8, a horizontal axis is an average particle diameter of the silica powder used in order to produce a ceramic substrate, and a vertical axis is a measurement result of arithmetic average roughness of the produced ceramic substrate, respectively. Show.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 High reflectance phase 3 Photoelectric conversion element 4 Recessed part

Claims (5)

A ceramic substrate for mounting a photoelectric conversion element for mounting a photoelectric conversion element that emits light, is formed by molding and firing ceramic powder, contains alumina, silica, and magnesia, and contains alumina as a main component. silica content of 0.1 to 1 wt%, magnesia content of Ri 0.01% by mass, and silica, the content of components other than magnesia and alumina following der Ru high 2 wt% A ceramic substrate for mounting a photoelectric conversion element, characterized by having a reflectance phase.   2. The ceramic substrate for mounting a photoelectric conversion element according to claim 1, wherein an average particle diameter of alumina powder in the ceramic powder is in a range of 0.3 to 1 μm.   The ceramic substrate for mounting a photoelectric conversion element according to claim 1 or 2, wherein an average particle diameter of silica powder in the ceramic powder is 1 µm or less.   The ceramic substrate for mounting a photoelectric conversion element according to any one of claims 1 to 3, wherein a cover phase having a silica content smaller than that of the high reflectance phase is formed outside the high reflectance phase. . 5. The photoelectric conversion element mounting device according to claim 4 , wherein the cover phase is formed by subjecting a layer having the same composition as the high reflectivity phase to a chemical treatment to elute silica. Ceramic substrate.

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