JP4818300B2 - Electronic component firing setter and method for manufacturing the same - Google Patents

Description

  The present invention relates to a setter for firing electronic components and a method for producing the same.

  Electronic parts such as ceramic capacitors are mainly used as built-in parts of mobile phones, and have a structure in which ceramic sheets such as titanium oxide and barium titanate and comb electrodes such as Ni are alternately stacked. The setter used for firing electronic components such as a ceramic capacitor having such a structure has the mechanical strength and heat resistance characteristics required for a general ceramic firing setter, It is necessary that no reaction is induced between electronic components such as capacitors, and that impurities contained in the setter for firing electronic components do not diverge or emit.

Conventionally, as a setter for firing an electronic part such as a ceramic capacitor having such a property, ZrO an _Al 2 _{O 3} quality mineral and _{Al 2 O} 3 -SiO 2 quality minerals on the upper surface of the substrate to aggregate _A setter for firing provided with a surface coat layer such as _two layers has been used.

In the setter for firing electronic parts and the like, it is important to improve the thermal shock resistance during actual use. In general, it is effective to increase the strength of the base material in order to improve the thermal shock resistance, but the base material using the Al ₂ O ₃ mineral and the Al ₂ O ₃ —SiO ₂ mineral as an aggregate is Since the aggregate particles are relatively large, such as several 100 μm to several mm, cracks tend to occur and the strength tends to be low. In such a low-strength material, in order to increase the thermal shock resistance, it is common to contain pores in the base material to some extent, thereby inhibiting crack propagation and increasing the thermal shock resistance. Also in the setter, the thermal shock resistance was improved by setting the porosity of the base material to around 20%. (Patent Document 1).

Since the ZrO ₂ layer used as the surface coat layer has a porosity of about 20%, the chemical substance derived from the capacitor can permeate from the setter surface layer to the substrate. Therefore, when a capacitor is fired using a setter having the above structure, a chemical reaction is induced between the capacitor and the chemical substance derived from the capacitor in the base material of the setter. There was a problem that became shorter.

  Further, along with the recent trend toward miniaturization and higher functionality of mobile phones, electronic components such as ceramic capacitors are also required to be smaller and higher performance. From the viewpoint of firing kiln efficiency, a setter used for firing such a small and lightweight electronic component is desired to have a thin setter to reduce the heat capacity.

  Conventionally, molding of electronic component firing setters is generally performed by casting from the viewpoint of securing strength. However, in casting molding, the water in the mud is adsorbed by the gypsum mold during the pouring process, increasing the viscosity of the slurry and losing fluidity. . In addition, in order to obtain a homogeneous molded body by general press molding, a thickness of 5 mm or more is required. Therefore, in a conventional setter in which the aggregate particle size of the base material is several hundred μm to several mm, press molding is used. It was difficult to achieve sufficient thinning.

As a thinning technique, for example, a technique is disclosed in which a film formed by thermal spraying on a stainless steel plate is peeled off by a difference in thermal expansion coefficient to manufacture a thin setter. However, according to this method, the electrode component adheres to the sprayed film during spraying and becomes an impurity, and the purity of the surface part that comes into contact with the object to be fired is considerably lower than the purity of the input material. There is a problem that is difficult. (Patent Document 2).
JP 2002-145672 A Japanese Patent Laid-Open No. 10-47867

  An object of the present invention is to solve the problems of the prior art described above, and to prevent deterioration of the setter due to a chemical reaction inside a setter for firing an electronic component such as a ceramic capacitor, and to improve the durability, the setter for firing an electronic component And a method of manufacturing the same.

  Another object of the present invention is to provide a setter for firing an electronic component and a method for producing the same that can reduce the heat capacity without impairing the durability.

The electronic component firing setter manufacturing method according to claim 1, which has been made to solve the above-described problems, includes a main body having an electronic component mounting surface and legs that form a column for forming a space between a plurality of stacked setters. Is a manufacturing method of integrally forming a setter for firing an electronic component having a part by gel casting , and firing a slurry mainly composed of an alumina raw material having a particle size of submicron to several tens of μm and a purity of 90% or more After the thin plate is formed so that the subsequent plate thickness is 2 mm or less, sintering is performed until the porosity becomes 1% or less. The invention according to claim 2 is characterized in that, in the method for manufacturing a setter for firing electronic parts according to claim 1, the purity of the alumina raw material is 95% or more, and the invention according to claim 3 Is a method for producing a setter for firing electronic parts according to claim 1, wherein the purity of the alumina raw material is 99.5% or more.

  The setter for firing electronic parts according to claim 4 is a setter for firing electronic parts manufactured by the method according to any one of claims 1 to 3, wherein the porosity is 1% or less and the bending strength is 250 MPa or more. It is characterized by being.

  The invention according to claim 5 is characterized in that the electronic component firing setter according to claim 4 is used as a base material, and the surface layer in contact with the object to be fired has a coating layer mainly composed of stabilized zirconia. It is.

  According to a sixth aspect of the present invention, in the electronic component firing setter according to the fifth aspect, one or more intermediate layers are provided between the substrate and the surface layer.

  The invention according to claim 7 is the electronic component firing setter according to any one of claims 4 to 6, wherein Ra of the electronic component placement surface is a rough surface of 5 to 50 inclusive. is there.

  Invention of Claim 8 is the setter for electronic component baking in any one of Claims 4-7, The main body which has an electronic component mounting surface, The support | pillar for forming space between the setters stacked in multiple numbers It has the leg part which becomes, It is characterized by the above-mentioned.

In the present invention, when manufacturing a setter for firing an electronic component having a main body having an electronic component mounting surface and a leg portion as a support for forming a space between a plurality of stacked setters, the particle size is submicron to several A slurry mainly composed of an alumina raw material having a thickness of 10 μm and a purity of 90% or more is integrally formed by a gel casting method so that the plate thickness after firing becomes 2 mm or less, and then fired until the porosity becomes 1% or less. With this structure, it is possible to improve the durability by suppressing the deterioration inside the setter due to the chemical reaction during the firing of electronic parts, and at the same time to realize thinning. In addition, production efficiency is improved by simplifying the setter manufacturing process.

Here, if the purity is less than 90%, the base material is deformed by its own weight and product load when the setter is used. Therefore, the higher the purity, the more effective. Further, the higher the purity, the more effective the reaction with the object to be fired. Specifically, the purity is required to be 90% or more, preferably 95% or more, and more preferably 99.5% or more. Here, when the base material is a single material of alumina of 99.5% or more, it is possible to avoid the problem that the SiO ₂ derived from the base material has become a contamination source that deteriorates the characteristics of the ceramic capacitor. An intermediate layer or a surface layer provided for the purpose of suppressing the reaction at the time becomes unnecessary, and the setter manufacturing process can be shortened.

Further, the strength can be increased by densifying so that the porosity is 1% or less. The strength is preferably 250 MPa or more. If it is less than this, the frequency of breakage due to thermal shock increases. Preferably, it is 300 MPa or more. Increased strength is expected to improve thermal shock resistance, and the setter can be made thinner. Specifically, by setting the thickness of the setter to 2 mm or less, the heat capacity of the setter is reduced and the firing kiln efficiency is improved. As a result, CO ₂ emission reduction and cost reduction are possible.

According to the invention described in claim 5, when the purity of the base material is 99.5% or less, it is possible to avoid the problem that SiO ₂ derived from the base material becomes a contamination source that deteriorates the characteristics of the ceramic capacitor. Specifically, when the purity is lower than 99.5%, the main impurity is SiO ₂ , but SiO ₂ derived from this substrate is a contamination source that deteriorates the characteristics of barium titanate used as a dielectric of a ceramic capacitor. It can be. Then, by providing the coat layer concerning the invention of Claim 2, it can prevent that the impurity in a base material and a to-be-fired material contact directly, and can maintain the quality of a to-be-fired material.

According to the invention described in claim 6, when the alumina purity of the substrate is low, it is possible to avoid the problem that SiO ₂ derived from the substrate becomes a contamination source that deteriorates the characteristics of the ceramic capacitor. Specifically, the substrate-derived SiO ₂ is blocked by providing an Al ₂ O ₃ layer as an intermediate layer, and a stabilized ZrO ₂ layer stabilized by Y ₂ O ₃ , MgO, and CaO is provided as a surface layer. This makes it possible to control the reaction during firing of the ceramic capacitor.

  According to the invention described in claim 7, by setting Ra of the electronic component mounting surface to a rough surface of 5 or more and 50 or less, when Ra is 5 or less, the electronic component to be fired and the setter are in close contact with each other, Problems such as insufficient debinding during firing occur, and the problem that the characteristics are not satisfied is solved.On the other hand, when it is Ra50 or more, it is not preferable from the viewpoint of the efficiency of debinding of electronic parts. It is possible to solve the problem that the defect rate such as the surface of the setter fluttering increases and the cost becomes high.

  According to the eighth aspect of the present invention, it is possible to improve workability at the time of firing without separately requiring a support column when firing the electronic component.

  The setter according to the present invention is used for manufacturing electronic parts such as ceramic capacitors which are mainly used as built-in parts of mobile phones. Among these, ceramic capacitors are small and light electronic components, and high functionality is required. Therefore, the setter according to the present invention needs to completely prevent the ceramic capacitor from reacting with the setter material. On the other hand, improvement in firing kiln efficiency is required from the standpoint of improving productivity, demand for products superior in economic efficiency, and environmental considerations. On the other hand, the setter of the present invention solves the above problems by improving the forming material and shape thereof.

Hereinafter, the configuration of the present invention will be described in detail.
As described above, the setter of the present invention is made of an alumina sintered body having a purity of 90% or more, a porosity of 1% or less, and a bending strength of 250 MPa or more. Since this alumina sintered body is dense, it has the property that the reactants are difficult to diffuse. Further, since this alumina sintered body is dense and has a higher strength than a setter having a low alumina purity, for example, even when the plate thickness of the mounting surface is 2 mm or less, it is mechanical. A setter having excellent strength and a long life can be obtained.

The shape of the setter according to the present invention is such that, as shown in FIG. 1, a leg portion that becomes a support for forming a space between a plurality of setters is joined to a main body having an electronic component placement surface by integral molding. It consists of a plate with legs. The present invention enables integral molding into such a complicated shape by performing setter molding by a gel casting method.

  Here, the gel casting method will be described in detail. The gel cast method is a powder molding method according to the applicant's invention, and is produced by dispersing one or more powders selected from ceramic, glass, or metal in a dispersion medium using a dispersant. In this method, a slurry is cured by adding a reactive material that reacts with the dispersant to cause the dispersing function of the dispersant to disappear or decrease, thereby obtaining a powder compact having an arbitrary shape.

  The gel casting method is similar to mud casting, but mud casting loses fluidity and solidifies due to absorption of the solvent into the gypsum mold, whereas gel casting adds a hard resin. The difference is that the solvent in the molded body is solidified without being removed. According to the gel casting method, fluidity is ensured during pouring so that the molded body is faithfully transferred from the mold. Therefore, there exists an advantage that the freedom degree is high with respect to the shape of a molded object.

In the present invention, the adoption of the above-described method makes it possible to manufacture a thin-walled plate-shaped electronic component firing setter that is difficult with the conventional manufacturing method by integral molding.

  The Ra of the electronic component mounting surface is preferably a rough surface of 5 to 50, but the rough surface is processed by a mold used for gel cast molding, or is roughened after setter firing. But you can.

  Here, the electric discharge machining method uses a conductive material such as copper or graphite that is relatively easy to process as a tool electrode, and applies an impulse voltage of about 60 to 300 V between the workpiece material such as copper or cemented carbide. This is a processing method that makes intermittent spark discharge occur while applying, and utilizes the abnormal consumption phenomenon that occurs at that time.

Below, the manufacturing method suitable for manufacturing the setter which concerns on this invention is demonstrated.
First, as a material for forming a setter, a high-purity alumina raw material having a purity of 90% to 99.99% is used.

  Since the setter according to the present invention is molded by the gel cast method, first, the molding slurry is adjusted. The molding slurry is prepared by dispersing the powder in a dispersion medium to make a slurry and then adding a gelling agent, or by simultaneously adding and dispersing the powder and the gelling agent in the dispersion medium. That's fine.

  The dispersion medium is a liquid substance that can be chemically bonded to the gelling agent and solidify the slurry, and may be any liquid substance that can form a highly fluid slurry that is easy to cast. That is, any material having at least one reactive functional group for chemically bonding with the gelling agent may be used, while a liquid material having a viscosity as low as possible is used for forming a highly fluid slurry. It is preferable. In particular, in the present invention, it is preferable to use an ester having a total carbon number of 20 or less.

  The gelling agent may be any material that can be chemically bonded to the dispersion medium and solidify the slurry. Any gelling agent may be used as long as it has a reactive functional group capable of chemically reacting with the dispersion medium in the molecule, and any of a monomer, a polymer, a prepolymer, and the like may be used. However, the gelling agent of the present invention preferably uses a material having a low viscosity, specifically, a material having a viscosity at 20 ° C. of 3000 cps or less from the viewpoint of ensuring slurry fluidity. In particular, in the present invention, MDI (4,4′-diphenylmethane diisocyanate) -based isocyanate (resin) is preferably used. Here, “viscosity” means the viscosity of the gelling agent itself (viscosity when the gelling agent is 100%), and does not mean the viscosity of a commercially available gelling agent diluted solution.

  The viscosity of the molding slurry is preferably 30000 cps or less at 20 ° C., more preferably 20000 cps or less in consideration of workability during casting. The viscosity of the slurry can be adjusted not only by the viscosity of the dispersion medium or the gelling agent but also by the slurry concentration (powder percentage with respect to the total volume of the slurry). Usually, the slurry concentration is preferably 25 to 75% by volume, and more preferably 35 to 75% by volume in consideration of reducing cracks due to drying shrinkage.

  The molding slurry is cast with a mold that has been previously processed into the shape of the setter according to the present invention, and then the slurry is gelled and solidified to obtain a molded body. In order to make Ra of the mounting surface of the setter of the present invention a rough surface of 5 or more and 50 or less, a method of performing electric discharge machining on the mold surface in advance can be used.

  In the present invention, the molded product obtained as described above is then dried at a temperature of about 60 ° C. to 100 ° C. for 2 hours. Baking is preferably performed at a maximum temperature of 1650 ° C.

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

  In Example 1, the forming material is a high-purity alumina powder having an average particle size of 0.9 μm (purity 99.99%), and the sintering aid is magnesium oxide having an average particle size of 0.5 μm (purity 99.0%). Was used. As the dispersion medium, a mixture (hereinafter referred to as “ester”, viscosity (20 ° C.): 24 cps) having a mass ratio of triacetylene: dimethyl glutarate of 10:90 was used. MDI (4,4′-diphenylmethane diisocyanate) modified product (trade name: SBU0775: manufactured by Sumitomo Bayer Urethane) (hereinafter referred to as “MDI modified product”) was used as the gelling agent. Polymeric sunray copolymer A: trade name: Floren G700: manufactured by Kyoeisha Chemical Co., Ltd. (hereinafter referred to as “dispersant A”) is used as the dispersant.

  The molding slurry was added at room temperature (around 20 ° C.) with a dispersion medium (“Ester”) (24) mass% and a dispersant (“Dispersant A”) (1.8) mass% added and mixed. It was prepared by adding and dispersing a pure alumina powder (100) mass% and magnesium oxide (0.02) mass% to form a slurry, and further adding and dispersing a gelling agent (1.9) mass%.

  The prepared molding slurry was poured into a molding die and allowed to stand for 10 minutes to be gelled and solidified to obtain a molded body. The compact size was 200x200x2t. The molding die is such that the shape of the setter according to the present invention is formed in a joining space where two aluminum plates are subjected to electric discharge machining and the two aluminum plates after machining are joined.

  In the present invention, the mold processing applied to one of the two aluminum plates is transferred to the surface of the setter, that is, the mounting surface on which the electronic component is loaded, and the other aluminum mold plane is It is transferred to the back of the setter. Therefore, when the setter according to the present invention is a setter in which the leg portion is integrally molded, the leg portion is integrally molded by subjecting a piece of aluminum transferred to the surface of the setter to a recess in the leg portion. A setter can be easily obtained. Also, when the electronic component mounting surface of the setter is a rough surface with Ra of 5 or more and 50 or less, by performing electric discharge machining on one aluminum surface transferred to the surface of the setter, setter molding and roughening are performed. Surface processing can be facilitated in the same process.

  The cured product gelated by the above process is taken out from the mold and dried in the atmosphere at 60 to 100 ° C. for 2 hours. And a setter for firing electronic parts according to the present invention was obtained. When the plate thickness of the mounting surface on which the electronic components of the obtained setter were loaded was measured, the plate thickness was 2 mm or less, and when the bending strength was measured, it had a bending strength of 280 MPa.

  In Example 3, alumina powder (purity 99.5%) was used as a forming material. The following is the same as in Example 1.

  In Example 4, alumina powder (purity 95%) was used as a forming material. The following is the same as in Example 1.

  In Example 5, alumina powder (purity 90%) was used as a forming material. The following is the same as in Example 1.

  In Comparative Example 1, alumina powder (purity 85%) was used as the forming material. The following is the same as in Example 1.

  In the comparative example 2, it implemented using the manufacturing method similar to patent document 2. FIG.

  The amount of impurities in the fired bodies obtained in each Example was quantified by ICP, and the amount of deformation of the same lot sample in an electric furnace at 1350 ° C. was confirmed by its own weight.

  From the above results, it was found that a product having an alumina purity of 90% or less has a particularly large deformation amount and is not suitable for use. Moreover, in the comparative example 2 manufactured with the manufacturing method of patent document 2, the purity after baking will fall, and in the environment where a high purity jig is required, based on the purity of the original raw material, It turned out to be difficult to control the purity.

It is sectional drawing of the setter for electronic component baking by which the leg part was joined to the main body.

DESCRIPTION OF SYMBOLS 1 Electronic component mounting surface which is a rough surface of Ra 5 or more and 50 or less 2 Electronic component firing setter 3 A dense single layer structure made of alumina having a purity of 99.9% or more 4 Leg of electronic component firing setter

Claims (8)

An electronic component firing setter having a main body having an electronic component placement surface and a leg portion as a support for forming a space between a plurality of stacked setters is integrally formed by gel casting. ,
Slurry mainly composed of an alumina raw material having a particle size of submicron to several tens of μm and a purity of 90% or more is formed into a thin wall so that the plate thickness after firing is 2 mm or less, and until the porosity becomes 1% or less. A method for producing a setter for firing electronic parts, comprising sintering.   The method for producing a setter for firing electronic parts according to claim 1, wherein the purity of the alumina raw material is 95% or more.   The method for producing a setter for firing electronic parts according to claim 1, wherein the purity of the alumina raw material is 99.5% or more.   A setter for firing an electronic component manufactured by the method according to any one of claims 1 to 3, wherein the porosity is 1% or less and the bending strength is 250 MPa or more. .   A setter for firing an electronic component comprising the setter for firing an electronic component according to claim 4 as a base material and having a coating layer mainly composed of stabilized zirconia on a surface layer in contact with the object to be fired.   6. The electronic component firing setter according to claim 5, wherein one or more intermediate layers are provided between the base material and the surface layer.   7. The electronic component firing setter according to claim 4, wherein Ra of the electronic component placement surface is a rough surface of 5 to 50.   The electronic device according to any one of claims 4 to 7, further comprising: a main body having an electronic component placement surface; and a leg portion serving as a support for forming a space between a plurality of stacked setters. Setter for firing parts.

Images