JP2012012251A - Dielectric ceramic, method for producing the same and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic which can be obtained by fired at a low temperature, and nonetheless ensures sinterability, maintains flexural strength and has excellent dielectric characteristics, and to provide a method for producing the dielectric ceramic, and an electronic component.SOLUTION: The dielectric ceramic includes a main component which contains MgSiOand additives which contain a zinc oxide and a glass component, wherein in X-ray diffraction, the peak intensity ratio, I/I, of the X-ray diffraction peak intensity Iof zinc oxide remaining unreacted, for which 2θ is between 31.0° and 32.0° and between 33.0° and 34.0°, with respect to the peak intensity Iof MgSiOas the main phase, for which 2θ is between 36.0° and 37.0°, is ≤10%, and wherein the dielectric ceramic has a relative density of ≥96%.

Description

  The present invention relates to a dielectric ceramic used for an electronic component used in a high frequency region, a method for manufacturing the dielectric ceramic, and an electronic component.

  2. Description of the Related Art In recent years, mobile communication devices such as cellular phones, for which demand is increasing, use a so-called quasi-microwave high frequency band of about several hundred MHz to several GHz. For this reason, electronic components such as capacitors, filters, resonators, and circuit boards used in mobile communication devices are required to have various characteristics suitable for use in a high frequency band.

  A circuit board, which is one of the electronic components used in the high frequency band, is equipped with a conductor such as an electrode or wiring (hereinafter referred to as “conductor material”), an LC filter composed of a combination of a magnetic material and a dielectric material, Capacitors made by combining dielectric constant materials and low dielectric constant materials are built in to form circuits such as LC filters and capacitors.

  In the circuit board, it is necessary to reduce the relative dielectric constant εr of the board in order to reduce the signal delay due to the inter-wiring capacitance in the wiring layer. Further, in the circuit board, since the high frequency signal is not attenuated, it is necessary to increase the Qf value of the board (that is, to reduce the dielectric loss). Therefore, as a material for the circuit board, a dielectric material having a low relative dielectric constant εr at a use frequency and a large Qf value is required. Q is the reciprocal of the tangent tan δ of the loss angle δ, which is the difference between the actual current and voltage phase difference in the dielectric and the ideal current and voltage phase difference of 90 degrees, and f is the resonance frequency. The Qf value is represented by the product of the quality factor Q = 1 / tan δ and the resonance frequency f. As the Qf value increases, the dielectric loss decreases.

  In general, many materials having a low dielectric constant have a small dielectric loss and are used in devices in the microwave region. For example, an LC filter is formed by simultaneously firing a high dielectric constant material and a low dielectric constant material. The LC filter uses a low dielectric constant material having a high Q value so that a high self-resonant frequency can be obtained in the ceramic material of the portion constituting the L part, and a temperature characteristic is obtained by using a material having a good temperature characteristic and a high dielectric constant in the C part. An LC element having good characteristics and a high Q value can be realized.

  As such a dielectric material, for example, a dielectric ceramic containing forsterite (Mg2SiO4) as a main component and zinc oxide, boron oxide, alkaline earth metal oxide, copper compound, and lithium compound as subcomponents. A composition (hereinafter referred to as “forsterite composition”) has been proposed (see, for example, Patent Document 1). The forsterite-based composition can be fired at a temperature (low temperature) lower than the melting point of the metal Ag or Ag-based alloy (hereinafter referred to as Ag-based metal), which is a conductor material, and increases the strength as a substrate. Therefore, it is suitable for a dielectric material for a circuit board.

  Since the sintering temperature of the forsterite-based composition is about 1000 ° C. or lower and is lower than the sintering temperature of the conventional dielectric ceramic composition, the melting point is higher than that of conventionally used conductor materials such as Pd and Pt. Low, low resistance, and inexpensive Ag-based metal can be used as the conductor material. Therefore, the forsterite composition can be co-fired at a low temperature (a temperature lower than the melting point of the Ag metal). Therefore, when forming a circuit board using a forsterite-based composition, the forsterite-based composition is used as a low-temperature firing material (LTCC) that can be fired simultaneously with a conductor material such as an Ag-based metal. Circuits such as capacitors can be formed.

JP 2009-132579 A

  However, in the conventional forsterite composition, after sintering, the added sintering aid such as zinc oxide remains unreacted, so that the dielectric loss of the obtained dielectric ceramic increases. There's a problem.

  Also, when the amount of sintering aid added is reduced and the amount of unreacted sintering aid is reduced, the sintering property of the fired material obtained by firing the forsterite composition is impaired, the dielectric loss of the substrate, There is a problem of deteriorating the strength.

  For this reason, it is possible to prevent unreacted sintering aid from remaining after firing at a low temperature using a forsterite-based composition, and at the same time to completely react the sintering aid to ensure sinterability and resist bending. There is a need for dielectric ceramics that maintain strength and have excellent dielectric properties.

  The present invention has been made in view of the above, and is a dielectric having excellent dielectric characteristics while ensuring sinterability and maintaining bending strength while being able to be obtained by firing at a low temperature. It is an object of the present invention to provide a porcelain, a dielectric porcelain manufacturing method, and an electronic component.

In order to solve the above-described problems and achieve the object, the present inventors have intensively studied dielectric ceramics, dielectric ceramic manufacturing methods, and electronic parts. As a result, the dielectric ceramic comprising as a main component Mg2SiO4, in X-ray diffraction, while suppressing the peak intensity ratio of the zinc oxide present remains unreacted for Mg ₂ SiO ₄ which is the main phase, the dielectric ceramic relative It has been found that by increasing the density, the dielectric ceramic can secure sinterability, maintain the bending strength, and have excellent dielectric properties. The present invention has been completed based on such findings.

The dielectric ceramic according to the present invention includes a main component including Mg ₂ SiO ₄ and a subcomponent including zinc oxide and a glass component. In X-ray diffraction, 2θ of Mg ₂ SiO ₄ as a main phase is 36. The unreacted zinc oxide 2θ is 31.0 ° to 32.0 ° and 33.0 ° to 34.0 to the X-ray diffraction peak intensity I _A between .0 ° and 37.0 °. with the peak intensity ratio I _B / I _a of the X-ray diffraction peak intensity I _B is 10% or less in °, relative density, characterized in that 96% or more.

According to the above composition, the glass component contained as an auxiliary component plays a role as a liquid phase, promotes the reactivity between the unreacted sintering aid and Mg ₂ SiO ₄ , and fires the dielectric ceramic composition. The sintering aid remaining unreacted later can be reduced, and the sintering aid can be completely reacted, so that the sinterability of the dielectric ceramic can be ensured. In this case, the peak intensity ratio I _B / I _A in the X-ray diffraction of the dielectric ceramic is 10% or less, the relative density is 96% or more. As a result, the Q value of the dielectric ceramic can be increased, and the dielectric loss can be reduced. In addition, according to the above composition, the dielectric ceramic composition can be co-fired with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal), and the firing temperature of the dielectric ceramic composition decreases. A decrease in the bending strength of the dielectric ceramic produced can be suppressed.

  The dielectric ceramic composition is a raw material composition for dielectric ceramic, and the dielectric ceramic is a sintered body obtained by sintering the dielectric ceramic composition. Sintering is a phenomenon in which a dielectric ceramic composition becomes a sintered body (dielectric ceramic) and becomes a dense object by heating the dielectric ceramic composition. In general, the density, mechanical strength, etc. of the sintered body (dielectric ceramic) are increased as compared with the dielectric ceramic composition before heating. The sintering temperature is the temperature of the dielectric ceramic composition when the dielectric ceramic composition is sintered. Further, firing means a heat treatment for the purpose of sintering, and the firing temperature is the temperature of the atmosphere to which the dielectric ceramic composition is exposed during the heat treatment.

As a preferred embodiment of the present invention, the glass component preferably contains at least one glass containing Li ₂ O. When the glass component contains Li ₂ O, the reaction between the unreacted sintering aid and Mg ₂ SiO ₄ is further promoted, and after firing the dielectric ceramic composition, the unreacted firing remaining in the dielectric ceramic. Since the binder can be further reduced and the sintering assistant can be completely reacted, the sinterability of the dielectric ceramic can be secured more stably. For this reason, the Q value of the obtained dielectric ceramic can be further increased, and the dielectric loss can be further reduced. In addition, the bending strength of the dielectric ceramic can be further stabilized.

  As a preferred embodiment of the present invention, the content of the zinc oxide is preferably 10 parts by mass or more and 16 parts by mass or less. The zinc oxide (particularly ZnO) contributes to firing at a low temperature (a temperature lower than the melting point of the Ag-based metal) when the dielectric ceramic composition is fired simultaneously with the Ag-based metal. By setting the content of the product within the above range, the dielectric ceramic composition can be stably co-fired with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal) to obtain a dielectric ceramic. .

The production method of a dielectric ceramic according to the present invention includes the production of a dielectric ceramic containing a main component containing Mg ₂ SiO ₄ and a subcomponent containing zinc oxide and a glass component. heat treated by mixing the raw material powder of silicon, to prepare a Mg ₂ SiO ₄ crystal powder, the Mg ₂ SiO ₄ crystal powder, adding the zinc oxide and a glass component as a subcomponent material powder, the dielectric ceramic A dielectric ceramic composition producing step for obtaining a composition, and a firing step for obtaining a sintered body by firing the dielectric ceramic composition at a temperature of 800 ° C. or higher and 1000 ° C. or lower in an oxygen atmosphere, Zinc oxide that remains unreacted with respect to X-ray diffraction peak intensity I _{A when} 2θ of Mg ₂ SiO ₄ , which is the main phase of the sintered body, is between 36.0 ° and 37.0 ° in line diffraction 2θ of 31. ° with 32.0 ° and 33.0 peak intensity ratio I _B / I _A of the X-ray diffraction peak intensity I _B in ° from 34.0 ° is less than 10%, the relative density of 96% or more It is characterized by.

The dielectric ceramic composition having the above composition can be fired at a temperature of 800 ° C. or higher and 1000 ° C. or lower in an oxygen atmosphere, and can be simultaneously fired with an Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal). In addition, when the dielectric ceramic composition is fired at a low temperature (a temperature lower than the melting point of the Ag-based metal), the zinc oxide and glass component contained as subcomponents serve as a liquid phase, and the sintering aid that remains unreacted. The reaction between the agent and Mg ₂ SiO ₄ can be promoted. Thus, after firing the dielectric ceramic composition, the sintering aid remaining unreacted on the dielectric ceramic can be reduced and the sintering aid can be completely reacted. Sinterability can be ensured. At this time, the resulting dielectric porcelain, the peak intensity ratio I _B / I _A is 10% or less, the relative density is 96% or more. Thereby, the Q value of the obtained dielectric ceramic can be increased, and the dielectric loss can be reduced. In addition, when the dielectric ceramic composition is simultaneously fired with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal), the bending strength of the dielectric ceramic generated as the firing temperature of the dielectric ceramic composition is decreased. The decrease can be suppressed. For this reason, the bending strength of the dielectric ceramic obtained by firing at a low temperature (temperature lower than the melting point of the Ag-based metal) is improved as compared with the dielectric ceramic obtained by firing the conventional forsterite composition. Can do.

As a preferred embodiment of the present invention, it is preferable that at least one glass containing Li ₂ O is contained as the glass component. Since the glass component contains Li ₂ O, the reaction between the unreacted sintering aid and Mg ₂ SiO ₄ is further promoted, and after firing the dielectric ceramic composition, the unreacted sintering remains in the dielectric ceramic. Since the auxiliary agent can be further reduced and the sintering auxiliary agent can be completely reacted, the sinterability of the dielectric ceramic can be secured more stably. For this reason, the Q value of the obtained dielectric ceramic can be further increased, and the dielectric loss can be further reduced. In addition, the bending strength of the dielectric ceramic can be further stabilized.

  As a preferred embodiment of the present invention, the content of the zinc oxide is preferably 10 parts by mass or more and 16 parts by mass or less. The zinc oxide (particularly ZnO) contributes to firing at a low temperature (a temperature lower than the melting point of the Ag-based metal) when the dielectric ceramic composition is fired simultaneously with the Ag-based metal. By setting the content of the product within the above range, the dielectric ceramic composition can be stably fired simultaneously with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal).

  An electronic component according to the present invention includes a dielectric layer made of the dielectric ceramic according to any one of the above. Since the dielectric ceramic according to the present invention is used for the dielectric layer, the Q value is large and the dielectric loss is small. Therefore, characteristics suitable for use in a high frequency band can be obtained, and a highly reliable electronic component can be obtained. Can be provided.

  ADVANTAGE OF THE INVENTION According to the present invention, it is possible to obtain by firing at a low temperature, while ensuring sinterability, maintaining bending strength, and having excellent dielectric properties, a method for manufacturing the dielectric ceramic, and Electronic components can be provided.

FIG. 1 is a flowchart showing a method for manufacturing a dielectric ceramic according to the present embodiment. FIG. 2 is a conceptual cross-sectional view schematically showing one embodiment when the electronic component of this embodiment is an LC filter. FIG. 3 is a flowchart illustrating an example of a method for manufacturing an electronic component according to the present embodiment. FIG. 4 is an X-ray diffraction chart of Example 4 and Comparative Example 7.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes for suitably carrying out the present invention (hereinafter referred to as embodiments) will be described in detail. In addition, this invention is not limited by the content described in the following embodiment. In addition, constituent elements in the embodiments described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the components disclosed in the embodiments described below can be appropriately combined.

<Dielectric porcelain>
The dielectric ceramic according to the present embodiment includes a main component including Mg ₂ SiO ₄ and a subcomponent including ZnO and a glass component. In X-ray diffraction, 2θ of Mg ₂ SiO ₄ as a main phase is 36. The unreacted zinc oxide 2θ of 31.0 ° to 32.0 ° and 33.0 ° to 34.0 ° with respect to the X-ray diffraction peak intensity I _A between 0 ° and 37.0 ° with the peak intensity ratio I _B / I _a of the X-ray diffraction peak intensity I _B is 10% or less in and a relative density of 96% or more.

  In the present embodiment, the dielectric ceramic composition is a raw material composition for dielectric ceramic, and the dielectric ceramic is a sintered body obtained by sintering the dielectric ceramic composition. Sintering is a phenomenon in which a dielectric ceramic composition becomes a sintered body (dielectric ceramic) and becomes a dense object by heating the dielectric ceramic composition. In general, the density, mechanical strength, etc. of the sintered body (dielectric ceramic) are increased as compared with the dielectric ceramic composition before heating. The sintering temperature is the temperature of the dielectric ceramic composition when the dielectric ceramic composition is sintered. Further, firing means a heat treatment for the purpose of sintering, and the firing temperature is the temperature of the atmosphere to which the dielectric ceramic composition is exposed during the heat treatment.

  Whether the dielectric ceramic composition can be fired at a low temperature (low temperature sinterability) is evaluated by gradually lowering the firing temperature of the dielectric ceramic composition and firing the dielectric ceramic composition according to the present embodiment. The determination can be made based on whether the dielectric ceramic composition is sintered to such an extent that the desired ceramic high-frequency characteristics can be obtained. In addition, the dielectric characteristics of the dielectric ceramic according to the present embodiment can be evaluated by the Qf value, the change in the resonance frequency due to the temperature change (temperature coefficient τf of the resonance frequency), and the relative dielectric constant εr. The Qf value and the relative dielectric constant εr can be measured according to Japanese Industrial Standard “Test Method for Dielectric Properties of Fine Ceramics for Microwaves” (JIS R1627 1996).

<Main component>
The dielectric ceramic according to the present embodiment contains Mg ₂ SiO ₄ (forsterite) as a main component. Mg ₂ SiO ₄ has a function of reducing the dielectric loss of the dielectric ceramic because the single Qf value is 200,000 GHz or more and the dielectric loss is small. Mg ₂ SiO ₄ also has a function of lowering the relative dielectric constant εr of the dielectric ceramic because its relative dielectric constant εr is as low as about 6 to 7. Here, dielectric loss is a phenomenon in which part of high-frequency energy is dissipated as heat. As described above, the magnitude of the dielectric loss is the reciprocal Q (Q = 1 / tan δ) of the tangent tan δ of the loss angle δ, which is the difference between the actual current and voltage phase difference and the ideal current and voltage phase difference of 90 degrees. ). Evaluation of the dielectric loss of the dielectric ceramic uses a Qf value which is a product of the Q and the resonance frequency f. The Qf value increases as the dielectric loss decreases, and the Qf value decreases as the dielectric loss increases. Since the dielectric loss means the power loss of the high frequency device, it is preferable that the Qf value of the dielectric ceramic is large. In the present embodiment, the Q value is used for evaluating the dielectric loss.

From the viewpoint of reducing the dielectric loss of the dielectric ceramic, the proportion of Mg ₂ SiO _{4 in} the main component is preferably 100 parts by mass. However, in order to adjust the relative permittivity εr, main components other than Mg ₂ SiO ₄ Can be used in combination with Mg ₂ SiO ₄ . Examples of main components other than Mg ₂ SiO ₄ include magnesium titanate (MgTiO ₃ ) having a relative dielectric constant εr of about 17, and calcium titanate (CaTiO ₃ ) having a relative dielectric constant εr of about 200. .

The molar ratio of MgO and SiO ₂ which constitutes the mg ₂ SiO _4, the stoichiometrically MgO pair SiO ₂ is 2 to 1, this embodiment is not limited thereto, the present embodiment You may remove | deviate from stoichiometry within the range which does not impair the effect of the dielectric ceramic which concerns on a form. For example, MgO to SiO ₂ can be in the range of 1.9 to 1.1 to 2.1 to 0.9.

The content of Mg ₂ SiO ₄ in the dielectric ceramic according to the present embodiment is preferably the remainder obtained by removing each subcomponent described later from the entire dielectric ceramic. When the dielectric ceramic contains the main component Mg ₂ SiO ₄ under such conditions, the effect of reducing the dielectric loss and the relative permittivity εr can be obtained with certainty. In addition, when a component other than the above Mg ₂ SiO ₄ is included as a main component, the total of the main component is the remainder obtained by removing each subcomponent described later from the entire dielectric ceramic.

<Subcomponent>
The dielectric ceramic of the present embodiment is composed of a composition containing zinc oxide and a glass component as subcomponents with respect to Mg ₂ SiO _{4 as} the main component. The auxiliary component is used as a sintering aid for forming a liquid phase when the dielectric ceramic composition is fired. In particular, the glass component contained as a subsidiary component plays a role as a liquid phase, and promotes the reactivity between the unreacted sintering aid and the main component Mg ₂ SiO ₄ . As a result, the sintering aid remaining unreacted on the dielectric ceramic after firing the dielectric ceramic composition can be reduced and the sintering aid can be completely reacted. Consistency is ensured. As a result, the Q value of the obtained dielectric ceramic can be increased, and the dielectric loss can be reduced.

  In addition, zinc oxide and a glass component are added as a sintering aid for forming a liquid phase during firing of the dielectric ceramic composition, and are contained in the dielectric ceramic composition as subcomponents. The sintering temperature decreases. For this reason, when the dielectric ceramic composition is fired to produce the dielectric ceramic, the dielectric ceramic composition can be fired simultaneously with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal). A low temperature firing can be achieved, and a decrease in the bending strength of the dielectric ceramic caused by a decrease in the firing temperature of the dielectric ceramic composition can be suppressed. Therefore, the dielectric porcelain obtained by firing the conventional forsterite composition can be obtained with the bending strength of the obtained dielectric porcelain while allowing the dielectric ceramic composition to be fired at a low temperature (a temperature lower than the melting point of the Ag-based metal). This can be improved over the body porcelain.

Examples of zinc oxide include ZnO. The glass component preferably contains at least one glass containing Li ₂ O. By including Li ₂ O in the glass component, the reactivity between the unreacted sintering aid and Mg ₂ SiO ₄ is further promoted, and after firing the dielectric ceramic composition, the unreacted firing remaining in the dielectric ceramic. Since the binder can be further reduced and the sintering assistant can be completely reacted, the sinterability of the dielectric ceramic can be secured more stably. Thereby, the Q value of the obtained dielectric ceramic can be further increased, and the dielectric loss can be further reduced. In addition, the dielectric ceramic composition can be fired simultaneously with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal), and the bending strength of the dielectric ceramic can be secured more stably.

As such a glass component, for example, SiO ₂ —RO—Li ₂ O (RO contains at least one alkaline earth metal oxide) glass and B ₂ O ₃ —RO—Li ₂ O glass. What comprises any one or both is preferable. As glass component, _{specifically,} the SiO ₂ -RO-Li 2 O-based _glass, SiO ₂ -CaO-Li 2 O-based glass, SiO ₂ -SrO-Li ₂ O-based glass, SiO ₂ -BaO-Li ₂ O-based _{glass, SiO 2 -CaO-SrO-Li} 2 O -based _{glass, SiO 2 -BaO-CaO-Li} 2 O -based _{glass, SiO 2 -SrO-BaO-Li} 2 O -based glass, SiO ₂ -CaO-SrO such -BaO-Li ₂ O system glass. B ₂ O ₃ as the -RO-Li ₂ O-based _{glass, B 2 O 3 -CaO-Li} 2 O -based _{glass, B 2 O 3 -SrO-Li} 2 O -based _{glass, B 2 O 3 -BaO-Li} 2 O glass, B ₂ O ₃ —CaO—SrO—Li ₂ O glass, B ₂ O ₃ —BaO—CaO—Li ₂ O glass, B ₂ O ₃ —SrO—BaO—Li ₂ O glass, B Examples include ₂ O ₃ —CaO—SrO—BaO—Li ₂ O-based glass. Among these, SiO ₂ —BaO—CaO—Li ₂ O-based glass is preferable.

  The content of the zinc oxide is preferably 8.0 parts by mass or more and 20 parts by mass or less, and preferably 10 parts by mass or more and 16 parts by mass or less with respect to 100 parts by mass of the main component when the mass of the zinc oxide is converted to ZnO. More preferably, it is 1 part by mass or more and 16.0 parts by mass or less. Zinc oxide (particularly ZnO) contributes to firing at a low temperature (a temperature lower than the melting point of the Ag-based metal) when the dielectric ceramic composition is fired simultaneously with the Ag-based metal. Therefore, by setting the content of zinc oxide within the above range, the dielectric ceramic composition can be stably co-fired with the Ag-based metal at a low temperature (a temperature lower than the melting point of the Ag-based metal). Become.

  When the zinc oxide content is less than 8.0 parts by mass, the low-temperature sintering effect (that is, the effect that enables the dielectric ceramic composition to be sintered at a lower temperature) tends to be insufficient. The sintered density of the dielectric ceramic decreases, the quality factor Q decreases, the dielectric loss tends to increase, and the effect of improving the bending strength tends to decrease. On the other hand, when the content of zinc oxide exceeds 20 parts by mass, the quality factor Q tends to decrease and the dielectric loss tends to increase. Therefore, by setting the content of zinc oxide within the above range, these tendencies can be suppressed.

The content of the glass component which is a kind of subcomponent is 100 parts by mass of the dielectric composition excluding the glass component from the subcomponent when the mass of the glass component is converted to SiO ₂ —BaO—CaO—Li ₂ O-based glass. On the other hand, it is preferably 2.0 parts by mass or more and 10.0 parts by mass or less, and more preferably 2.0 parts by mass or more and 7.0 parts by mass or less.

  When the content of the glass component is less than 2.0 parts by mass, the low-temperature sintering effect is insufficient, the sintering is insufficient, the sintered density of the dielectric ceramic according to this embodiment is reduced, and the quality factor Q is The dielectric loss tends to increase and the dielectric loss tends to increase, and the effect of improving the bending strength tends to decrease. Moreover, when content of a glass component exceeds 10.0 mass parts, the quality factor Q will fall and there exists a tendency for a dielectric loss to become large. Therefore, by setting the content of the glass component within the above range, these tendencies can be suppressed.

In the dielectric ceramic according to the present embodiment, for example, a boron oxide, an alkaline earth metal oxide, or the like may be included as a component included in the subcomponent in addition to the zinc oxide and the glass component. Specific examples of the boron oxide include B ₂ O ₃ . Examples of the alkaline earth metal oxide include BaO, SrO, CaO, and MgO.

The content of the boron oxide is preferably 3.0 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the main component when the mass of the boron oxide is converted to B ₂ O ₃ . It is more preferable that it is 4.0 parts by mass or more and 8.0 parts by mass or less.

  If the boron oxide content is less than 3.0 parts by mass, the low-temperature sintering effect tends to be insufficient, the quality factor Q tends to decrease, and the dielectric loss tends to increase. On the other hand, if the content of boron oxide exceeds 10.0 parts by mass, the sintered density of the dielectric ceramic is likely to be lowered, the quality factor Q is lowered to increase the dielectric loss, and the bending strength is improved. The effect tends to be small. Therefore, by setting the content of boron oxide within the above range, these tendencies can be suppressed.

  Content of alkaline-earth metal oxide is 1.0 mass with respect to 100 mass parts of main components, when the mass of alkaline-earth metal oxide is converted into RO (R shows an alkaline-earth metal element). Part or more and 4.0 parts by weight or less is preferable, and 1.0 part by weight or more and 3.0 parts by weight or less is more preferable. By including the alkaline earth metal oxide in the dielectric ceramic composition, the low-temperature sintering effect of the dielectric ceramic composition becomes remarkable.

  When the content of the alkaline earth metal oxide is less than 1.0 part by mass, the low-temperature sintering effect tends to be insufficient, and the sintered density of the dielectric ceramic according to the present embodiment tends to be low. The quality factor Q decreases and the dielectric loss increases, and the effect of improving the bending strength tends to decrease. On the other hand, when the content of the alkaline earth metal oxide exceeds 4.0 parts by mass, although the low-temperature sintering effect becomes remarkable, the quality factor Q tends to decrease and the dielectric loss tends to increase. Therefore, by setting the content of the alkaline earth metal oxide within the above range, these tendencies can be suppressed.

  As R which is an alkaline earth metal, any one of Ba, Sr and Ca is preferable, and two or more of these may be mixed and used. Specific examples of the alkaline earth metal oxide RO include MgO, CaO, SrO, BaO and the like.

The dielectric ceramic according to the present embodiment, the peak intensity ratio I _B / I _A in the X-ray diffraction is 10% or less, preferably 5% or less, more preferably 0%. When the peak intensity ratio I _B / I _A exceeds 10%, sinterability of the dielectric ceramic becomes insufficient and enough strength can not be obtained.

In X-ray diffraction, the X-ray diffraction peak intensity I _A of Mg ₂ SiO ₄ which is the main phase has a maximum peak between 2θ of 36.0 ° and 37.0 °, and the X-ray diffraction peak of zinc oxide Intensity I _B occurs between 2θ between 31.0 ° and 32.0 ° and between 33.0 ° and 34.0 °. The zinc oxide remaining unreacted can be confirmed from the X-ray diffraction peak intensity I _{B. By} comparing with the X-ray diffraction peak intensity I _A , the zinc oxide remaining unreacted in the main component can be confirmed. The ratio of objects can be confirmed. Zinc oxide that remains unreacted in the main component affects the sinterability of the dielectric ceramic when the dielectric ceramic composition is sintered, reduces the sintered density of the dielectric ceramic, and reduces the Q value. Reduce. Accordingly, the peak intensity ratio I _B / I _A is 10% or less, by reducing the proportion of zinc oxide remaining remains unreacted in the main component to ensure sinterability of the dielectric ceramic, dielectric The sintered density of the porcelain can be improved, and the Q value can be increased.

The angle of 2θ of Mg ₂ SiO _{4 having} an X-ray diffraction peak intensity I _A is set in a range between 36.0 ° and 37.0 °, but as described later, when a dielectric ceramic composition is manufactured. In addition, zinc oxide or glass component is added to the Mg ₂ SiO ₄ crystal powder as a subcomponent raw material powder, and slightly varies depending on the composition ratio of subcomponents contained in the dielectric ceramic, so that Mg ₂ SiO ₄ The 2θ angle is preferably in the range between 36.0 ° and 36.5 °, more preferably in the vicinity of 36.3 °.

The 2θ angle of the unreacted zinc oxide with the X-ray diffraction peak intensity I _B is in the range between 31.0 ° to 32.0 ° and 33.0 ° to 34.0 °, respectively. However, in the same manner as described above, since it slightly varies depending on the composition ratio of the subcomponents contained in the dielectric ceramic, 31.0 ° to 32% of the 2θ angle of the zinc oxide remaining unreacted. The value of 0.0 ° is preferably in the range between 31.5 ° and 32.0 °, more preferably around 31.8 °. Of the 2θ angles of the zinc oxide that remains unreacted, the angle of 33.0 ° to 34.0 ° is preferably within the range of 33.3 ° to 33.8 °, and 33.6 ° The vicinity of ° is more preferable.

In the dielectric ceramic according to this embodiment, the relative density is 96% or more, and preferably 99% or more. The relative density indicates the firing property when the dielectric ceramic composition is fired. This is because, when the relative density is less than 96%, the sinterability of the dielectric ceramic becomes insufficient, and the Q value and the strength of the dielectric ceramic are reduced. When the main component of the dielectric ceramic composition is Mg ₂ SiO ₄ and the subcomponents are ZnO, B ₂ O ₃ , CaCO _3, and SiO ₂ —BaO—CaO—Li ₂ O glass, a dielectric having the same composition When the sintering density ρs was measured while changing the firing temperature and time of the porcelain composition, the value of the sintering density ρs was 3.35 g / cm ³ . The value of the sintering density ρs of the dielectric ceramic slightly varies depending on the composition ratio of the main component and the subcomponent of the dielectric ceramic, but the relative density is, for example, the value of the sintering density ρs of the dielectric ceramic is 3. The time of 35 g / cm ³ can be determined by defining the relative density as 100%. Therefore, since the sinterability of the dielectric ceramic can be ensured by setting the relative density of the dielectric ceramic according to the present embodiment to 96% or more, the sintered density of the dielectric ceramic obtained is good, and the Q value is The dielectric loss can be lowered and the bending strength can be raised.

A decrease in the Q value means that the loss of the electronic component becomes large. The larger the Q value, the smaller the loss of the electronic component. The dielectric ceramic according to the present embodiment, the content of zinc oxide and a glass component in a range similar to the dielectric ceramic composition, a peak intensity ratio I _B / I _A in the X-ray diffraction is 10% or less At the same time, the relative density is set to 96% or more. As a result, the dielectric ceramic according to the present embodiment can ensure sinterability and bending strength, increase the Q value, and reduce the dielectric loss. For this reason, the Q value of the dielectric ceramic according to the present embodiment can be maintained at a predetermined value (for example, 1000) or more while achieving low-temperature sintering of the dielectric ceramic composition. Therefore, the dielectric ceramic according to the present embodiment can provide a dielectric ceramic that can be fired at a low temperature and is used for an electronic component having a low melting point conductor material such as an Ag-based metal as an internal electrode.

As described above, the dielectric ceramic according to the present embodiment includes Mg ₂ SiO ₄ as a main component, zinc oxide and a glass component as subcomponents, and has a peak intensity ratio I _B / I _A in X-ray diffraction. In addition to 10% or less, the relative density is 96% or more. The glass component contained as a subcomponent in the dielectric ceramic according to the present embodiment plays a role as a liquid phase when firing the dielectric ceramic composition, and the sintering aid remaining unreacted with Mg ₂ SiO ₄ Reaction can be promoted, and even if the dielectric ceramic composition is fired at a low temperature, the unreacted sintering aid is eliminated and the sintering aid is completely reacted to ensure the sinterability of the dielectric ceramic. can do. In this case, the peak intensity ratio I _B / I _A of the dielectric ceramic according to the present embodiment with 10% or less, relative density is 96% or more. Thereby, the Q value of the obtained dielectric ceramic can be increased, and the dielectric loss can be reduced. In addition, according to the above composition, the dielectric ceramic composition can be fired simultaneously with the Ag-based metal at a low temperature that does not melt the Ag-based metal, and the resistance generated as the firing temperature of the dielectric ceramic composition decreases. A decrease in bending strength can be suppressed. For this reason, the bending strength of the dielectric ceramic obtained by firing at a low temperature can be improved as compared with the dielectric ceramic obtained by firing the conventional forsterite composition. Therefore, the dielectric ceramic according to the present embodiment can be obtained by firing at a low temperature, while ensuring sinterability, maintaining the bending strength, and reducing the dielectric loss.

<Dielectric porcelain manufacturing method>
An example of a method for manufacturing a dielectric ceramic according to the present embodiment will be described. FIG. 1 is a flowchart showing a method for manufacturing a dielectric ceramic according to the present embodiment. As shown in FIG. 1, the method for manufacturing a dielectric ceramic according to the present embodiment includes the following steps when manufacturing a dielectric ceramic including a main component including Mg ₂ SiO ₄ and a subcomponent including ZnO and a glass component. These steps are included.
(A) by mixing a raw material powder of the raw material powder and silicon dioxide magnesium oxide was heat-treated, Mg ₂ SiO ₄ to produce a crystalline powder Mg ₂ SiO ₄ crystal powder manufacturing process (step S11)
(B) Step of producing a dielectric ceramic composition by adding the zinc oxide and glass component as subcomponent raw powder to Mg ₂ SiO ₄ crystal powder to obtain a dielectric ceramic composition (step S12)
(C) A firing step of firing the dielectric ceramic composition at a temperature of 800 ° C. or higher and 1000 ° C. or lower in an oxygen atmosphere to obtain a sintered body (step S13).

<Mg ₂ SiO ₄ crystal powder production process: step S11>
The Mg ₂ SiO ₄ crystal powder production step (step S11) is performed by mixing a magnesium oxide (MgO) raw material powder and a silicon oxide (SiO ₂ ) raw material powder and calcining them to produce forsterite (Mg ₂ SiO ₄ ). This is a process for producing crystal powder. A predetermined amount of raw material powder of MgO and raw material powder of SiO ₂ as raw materials for Mg ₂ SiO ₄ crystal powder are weighed and mixed. Thereby, raw material mixed powder is obtained. The subcomponents are weighed so that the content of each subcomponent is the desired ratio (parts by mass) with respect to the entire dielectric ceramic composition in the finished dielectric ceramic composition. Do. Further, the mixing of the MgO raw material powder and the SiO ₂ raw material powder can be performed by a mixing method such as dry mixing or wet mixing, for example, using a solvent such as pure water or ethanol in a mixing and dispersing machine such as a ball mill. And mix. The mixing time in the case of a ball mill is about 4 to 24 hours.

The raw material mixed powder is preferably dried at 100 ° C. or higher and 200 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower for about 12 to 36 hours, and then heat treatment (calcination). By this calcination, Mg ₂ SiO ₄ crystals are obtained. The calcination temperature is preferably 1100 ° C. or more and 1500 ° C. or less, and preferably 1100 ° C. or more and 1350 ° C. or less. The calcining time is preferably about 1 to 24 hours.

The synthesized Mg ₂ SiO ₄ crystal is pulverized into a powder and then dried. Thereby, Mg ₂ SiO ₄ crystal powder is obtained. This Mg ₂ SiO ₄ crystal powder is used as the main component powder of the dielectric ceramic. The pulverization can be performed by a pulverization method such as dry pulverization or wet pulverization. For example, wet pulverization is performed with a ball mill using a solvent such as pure water or ethanol. The pulverization time is not particularly limited, and it is sufficient that an Mg ₂ SiO ₄ crystal powder having a desired average particle size is obtained. The pulverization time may be, for example, about 4 to 24 hours. The Mg ₂ SiO ₄ crystal powder is preferably dried at a drying temperature of 100 ° C. to 200 ° C., more preferably 120 ° C. to 140 ° C. for about 12 to 36 hours.

In order to increase the effect of Mg ₂ SiO ₄ crystal, it is necessary to reduce the raw material components of unreacted MgO and SiO ₂ contained in Mg ₂ SiO ₄ , so MgO and SiO ₂ were mixed. When preparing the raw material mixed powder, it is preferable to mix MgO and SiO ₂ so that the number of moles of magnesium is twice that of silicon.

The Mg ₂ SiO ₄ crystal powder is not limited to the method of synthesizing the Mg ₂ SiO ₄ crystal from the MgO raw material powder and the SiO ₂ raw material powder, and commercially available Mg ₂ SiO ₄ may be used. In this case, commercially available Mg ₂ SiO ₄ may be pulverized by the same method as described above and dried to obtain Mg ₂ SiO ₄ crystal powder.

After obtaining the Mg ₂ SiO ₄ crystal powder, the process proceeds to the dielectric ceramic composition manufacturing step (step S12).

<Production process of dielectric ceramic composition: Step S12>
In the dielectric ceramic composition manufacturing step (step S12), the zinc oxide and the glass component are added to the Mg ₂ SiO ₄ crystal powder as subcomponent raw powders to obtain a dielectric ceramic composition. This is a manufacturing process.

A predetermined amount of the obtained Mg ₂ SiO ₄ crystal powder and zinc oxide which is a raw material of the accessory component of the dielectric ceramic composition are weighed, and then mixed and heat-treated. The powder after heat treatment of the Mg ₂ SiO ₄ crystal powder and the subcomponent raw material powder is added with a glass component and pulverized to obtain a dielectric ceramic composition. In this embodiment, the glass component is added to the powder obtained by heat treatment after mixing the Mg ₂ SiO ₄ crystal powder and zinc oxide, but this embodiment is limited to this. Instead, the glass component may be mixed when the Mg ₂ SiO ₄ crystal powder and zinc oxide are mixed and heat-treated. Examples of zinc oxide include ZnO as described above. As described above, the glass component preferably contains at least one glass containing Li ₂ O. As the glass component, for example, those composed include one or both of the SiO ₂ -RO-Li ₂ O-based glass and _{B 2 O 3 -RO-Li 2} O system glass is preferred. Since the glass component contains Li ₂ O, the reaction between the sintering aid that remains unreacted and Mg ₂ SiO ₄ can be promoted, so that the sinterability of the dielectric ceramic is further stabilized. The Q value of the dielectric ceramic can be further increased, and the dielectric loss can be further reduced. In addition, the dielectric ceramic composition can be simultaneously fired with the Ag-based metal at a low temperature at which the Ag-based metal is not melted, and the bending strength can be secured more stably.

A compound that becomes a glass containing zinc oxide and Li ₂ O by firing by a heat treatment such as calcining described later can also be used as a raw material for the auxiliary component. In addition to zinc oxide and glass components, raw materials for subcomponents of the dielectric ceramic composition include, for example, boron oxide, alkaline earth metal oxide, or firing (heat treatment such as calcining described later). A compound that becomes an oxide can be used. Examples of the boron oxide include B ₂ O ₃ . Examples of the alkaline earth metal oxide include BaO, SrO, CaO, and MgO. Examples of the compound that becomes the oxide upon firing include carbonates, nitrates, oxalates, hydroxides, sulfides, organometallic compounds, and the like. Examples of the boron oxide include B ₂ O ₃ . Examples of the alkaline earth metal oxide include BaO, SrO, CaO, and MgO.

The weighing of each raw material of zinc oxide and glass component is performed so that the content of zinc oxide and glass component becomes a desired mass ratio (part by mass) with respect to the main component in the finished dielectric ceramic. Do. That is, the content of zinc oxide is preferably 8.0 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the main component when the mass of zinc oxide is converted to ZnO. More preferably, it is at least 1 part by mass and no more than 16.0 parts by mass. The content of the glass component is 2.0 with respect to 100 parts by mass of the dielectric composition excluding the glass component from the subcomponent when the mass of the glass component is converted to SiO ₂ —BaO—CaO—Li ₂ O glass. It is preferable that it is no less than 10.0 parts by mass and more preferably no less than 2.0 parts by mass and no greater than 7.0 parts by mass.

  In addition to zinc oxide and glass component as a component contained in the subcomponent, for example, when boron oxide, alkaline earth metal oxide, etc. are included, for the content of boron oxide and alkaline earth metal oxide, As above-mentioned, it carries out so that it may become the said desired mass ratio (mass part) with respect to a main component, respectively.

  Mixing can be performed by a mixing method such as dry mixing or wet mixing, and for example, can be performed by a mixing method using a solvent such as pure water or ethanol with a mixing and dispersing machine such as a ball mill. The mixing time may be about 4 to 24 hours.

  The raw material mixed powder is preferably dried at a drying temperature of 100 ° C. to 200 ° C., more preferably 120 ° C. to 140 ° C. for about 12 to 36 hours.

The dried raw material mixed powder is heat-treated (calcined) at 800 ° C. or higher and 950 ° C. or lower for about 1 to 10 hours, for example. Thus, by performing calcination at a temperature lower than the firing temperature, it is possible to suppress melting of the forsterite in the raw material mixed powder, and the dielectric ceramic composition contains Mg ₂ SiO ₄ in the form of crystals. be able to.

Li-based glass such as glass containing Li ₂ O is added to the raw material mixed powder after calcination, mixed and pulverized, and then dried. Thereby, a dielectric ceramic composition is obtained. The pulverization can be performed by a pulverization method such as dry pulverization or wet pulverization. The pulverization time may be about 4 to 24 hours. Drying of the raw material mixed powder after pulverization is preferably performed at a treatment temperature of 100 ° C. or higher and 200 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower for about 12 to 36 hours.

  By the above-described method for producing a raw material mixed powder that is a dielectric powder, the main component and subcomponent of the dielectric ceramic composition are uniformly mixed, and a dielectric ceramic composition having a uniform material can be obtained.

  After obtaining the dielectric ceramic composition, the process proceeds to a firing step (step S13) for firing the dielectric ceramic composition.

<Baking process: Step S13>
In the firing step (step S13), the obtained dielectric ceramic composition is fired to obtain a sintered body. Thereby, the dielectric ceramic according to the present embodiment is obtained. Firing is preferably performed, for example, in an oxygen atmosphere like air. The firing temperature is preferably not higher than the melting point of the Ag-based metal used as the conductor material. For example, it is preferably 800 ° C. or higher and 1000 ° C. or lower, more preferably 800 ° C. or higher and 950 ° C. or lower, and 860. It is more preferable that it is 950 degreeC or more, and it is most preferable that it is 880 degreeC or more and 940 degrees C or less.

Thus the dielectric ceramic obtained by using the manufacturing method of a dielectric ceramic according to the present embodiment, the peak intensity ratio I _B / I _A is not more than 10%, a relative density of 96% or more. For this reason, even when firing at a low temperature of 800 ° C. or more and 1000 ° C. or less in the firing step (step S13), the relative density of the dielectric ceramic is increased, and the content of ZnO remaining unreacted is reduced. Therefore, the dielectric ceramic according to the present embodiment can be obtained by firing at a low temperature in the firing step (step S13), ensuring the sinterability of the dielectric ceramic, maintaining the bending strength, and maintaining the dielectric loss. It is an excellent dielectric ceramic. Therefore, the dielectric ceramic according to the present embodiment can be suitably used as a dielectric ceramic constituting a part of electronic components such as a filter, a resonator, a capacitor, and a circuit board.

  The preferred embodiments of the dielectric ceramic according to the present invention have been described above, but the present invention is not necessarily limited to the above-described embodiments. For example, the dielectric ceramic according to the present invention can be fired at a low temperature, while ensuring sinterability, maintaining bending strength, and other compounds within a range that does not hinder the effect of reducing dielectric loss. It may be included.

<Electronic parts>
The dielectric ceramic of the present embodiment can be suitably used as a dielectric layer that constitutes a part of an electronic component such as a filter, a capacitor, a resonator, or a circuit board. FIG. 2 is a conceptual cross-sectional view schematically showing one embodiment when the electronic component of this embodiment is an LC filter. As shown in FIG. 2, the LC filter 10 includes a plurality of dielectric layers 11, a coil 12, capacitor pattern portions 13-1 to 13-3, and vias (via conductors) 14. The dielectric layer 11 uses the dielectric ceramic of this embodiment. The coil 12 and the capacitor pattern portions 13-1 to 13-3 are formed of an Ag conductor. The via 14 is a via hole portion filled with an Ag conductor that makes the coil 12 and the capacitor pattern portion 13-1 conductive, and an LC resonance circuit is formed. Capacitor pattern portion 13-1 is connected to coil 12 by via 14. Although the capacitor portion of the LC filter 10 has a three-layer structure, the LC filter 10 is not limited to a three-layer structure, and can have an arbitrary multilayer structure. In the LC filter 10, since the dielectric ceramic according to the present embodiment is used for the dielectric layer 11, the dielectric layer 21 secures a bending strength and suppresses a decrease in dielectric loss. In addition, the strength of the dielectric layer 11 can be maintained, the Q value is high, and the dielectric loss is small, so that characteristics suitable for use in the high frequency band can be obtained. Therefore, the electronic component of this embodiment can be suitably used as an LC filter.

  The LC filter 10 manufactured in this way is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

  The electronic component according to the present embodiment is not limited to an electronic component in which the dielectric layer 11 and the capacitor pattern portions 13-1 to 13-3 are alternately stacked, like the LC filter 10 illustrated in FIG. However, any electronic component including a dielectric layer can be preferably used. Further, the dielectric ceramic according to the present embodiment can be suitably used even for an electronic component in which elements are further individually mounted outside. Other electronic components of the present embodiment include, for example, a capacitor, a resonator, a circuit board, a low-pass filter (Low-pass filter: LPF), a band-pass filter (BPF), a diplexer. (DPX), coupler (directional coupler), balun (or balun; balanced / unbalanced impedance converter), and the like can also be suitably used.

<Method for manufacturing electronic parts>
An example of a method for manufacturing an electronic component according to this embodiment will be described. FIG. 3 is a flowchart illustrating an example of a method for manufacturing an electronic component according to the present embodiment. As shown in FIG. 3, the manufacturing method of the electronic component according to the present embodiment is obtained by molding, laminating and firing a plurality of dielectric ceramic compositions manufactured by the dielectric ceramic manufacturing method shown in FIG. It is manufactured. In manufacturing the electronic component according to the present embodiment, the following steps are included.
(A) a mixture of magnesium oxide and silicon dioxide was heat-treated, Mg ₂ SiO ₄ to produce a crystalline powder Mg ₂ SiO ₄ crystal powder manufacturing process (step S21)
(B) The dielectric ceramic composition production process of obtaining the dielectric ceramic composition by adding the zinc oxide and the glass component as subcomponent raw powders to the Mg ₂ SiO ₄ crystal powder (step S22)
(C) A molded body manufacturing step of applying a paste containing a dielectric ceramic composition powder onto a substrate to manufacture a molded body (step S23).
(D) Laminate production process (step S24) in which a plurality of green sheets obtained by forming a molded body are laminated to obtain a laminate.
(E) Firing step of firing the laminated body at a temperature of 800 ° C. or higher and 1000 ° C. or lower in an oxygen atmosphere to obtain a sintered body (step S25)

<Mg ₂ SiO ₄ crystal powder manufacturing process steps for manufacturing a (step S21) and the dielectric ceramic composition (Step S22)>
The production process of Mg ₂ SiO ₄ crystal powder (step S21) and the production process of dielectric ceramic composition (step S22) are the production of the Mg ₂ SiO ₄ crystal powder shown in FIG. 1 when manufacturing the above-mentioned dielectric ceramic. Since it is the same as the process (step S11) and the production process of the dielectric ceramic composition (step S12), description thereof is omitted. After obtaining the dielectric ceramic composition, the process proceeds to a molded body manufacturing step (step S23) for manufacturing a molded body.

<Molded body production process: Step S23>
The molded body manufacturing process (step S23) is a process of manufacturing a molded body by applying a paste containing a dielectric ceramic composition powder on a substrate. The obtained dielectric ceramic composition powder is added to an organic binder such as polyvinyl alcohol, acrylic or ethyl cellulose, and then the resulting mixture is molded into a sheet to obtain a green sheet. As a green sheet molding method, there are wet molding methods such as a sheet method and a printing method. After producing a molded object, it transfers to the laminated body production process (step S24) which produces a laminated body.

<Laminated body production process: Step S24>
The laminate manufacturing step (step S24) is a step of obtaining a laminate by laminating a plurality of green sheets obtained by forming a molded body. In the laminate manufacturing step (step S24), a conductive paste containing Ag is applied on the green sheet obtained by molding so that an internal electrode having a predetermined shape is formed. A plurality of green sheets coated with a conductive paste are prepared as necessary, stacked and pressed to obtain a stacked body. After cutting the obtained laminated body into a desired size and chamfering, the process proceeds to a firing step (step S25) in which the chip is fired.

<Baking process: Step S25>
Since the firing process (step S25) is the same as the firing process (step S13) shown in FIG. 1 when manufacturing the above-described dielectric ceramic, the description thereof will be omitted. After cooling the sintered body, an external electrode or the like is formed on the obtained dielectric porcelain as necessary, thereby completing an electronic component in which the external electrode or the like is formed on the dielectric porcelain.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to a following example.

<Production of dielectric ceramic>
[Example 1]
Mg ₂ SiO ₄ as a main component, zinc oxide and glass component as subcomponents, the content of ZnO is 16 parts by mass with respect to 100 parts by mass of the main component, and the content of B ₂ O ₃ Is 6.0 parts by mass, the CaCO ₃ content is 2.0 parts by mass, and SiO ₂ —BaO—CaO—Li _{2 with} respect to 100 parts by mass of the dielectric composition excluding the glass component from the subcomponents. A dielectric porcelain having an O-based glass content of 2.0 parts by mass was produced by the following procedure.

First, MgO and SiO ₂ which are main component materials were weighed so that the number of moles of magnesium atoms was twice the number of moles of silicon atoms. Pure water was added to the weighed raw materials to prepare a slurry having a slurry concentration of 25 parts by mass. This slurry was wet mixed in a ball mill for 16 hours, and then dried at about 120 ° C. for 24 hours to obtain a raw material mixed powder. This raw material mixed powder was calcined in air at about 1200 ° C. for 3 hours to obtain Mg ₂ SiO ₄ crystals. Pure water was added to the Mg ₂ SiO ₄ crystal to prepare a slurry having a slurry concentration of 25%. This slurry was pulverized with a ball mill for 16 hours and then dried at 120 ° C. for 24 hours to produce Mg ₂ SiO ₄ crystal powder, which is the main component of the dielectric ceramic composition.

Next, ZnO, B ₂ O ₃ , CaCO ₃ and glass components which are raw materials of subcomponents of the dielectric porcelain composition are mixed and adjusted with respect to the obtained Mg ₂ SiO ₄ crystal powder, and the dielectric A porcelain composition powder was obtained. The amount of each component of the dielectric ceramic composition is 16 parts by mass of ZnO, 6.0 parts by mass of B ₂ O _{3 and} 2.0 parts by mass of CaCO ₃ with respect to 100 parts by mass of the Mg ₂ SiO ₄ crystal powder. parts, the dielectric composition 100 parts by weight excluding the glass component from subcomponent was adjusted to _{SiO 2 -BaO-CaO-Li 2} O system glass is 2.0 parts by weight.

After adding an organic binder or the like to the dielectric ceramic composition powder, a sheet was molded by the doctor blade method to produce a plurality of molded sheets. A plurality of sheet molded bodies were laminated and then pressed to form a substrate, thereby producing a sheet laminated molded body. After cutting this sheet laminated molded body into a desired size, the chip was chamfered and fired at a firing temperature (900 ° C.) at which Ag does not melt for 2.5 hours to produce a dielectric ceramic. And _Mg 2 SiO ₄ contained as the main component of the produced dielectric ceramic, the amount of each of the ZnO and B ₂ O ₃ and CaCO ₃ and _{SiO 2 -BaO-CaO-Li 2} O system glass contained as a sub-component Is shown in Table 1.

[Examples 2 to 12, Comparative Examples 1 to 10]
Dielectric porcelain compositions were prepared in the same manner as in Example 1 except that the content (% by mass) of Li ₂ O with respect to the entire dielectric porcelain composition was changed to the values shown in Table 1. And the sheet | seat laminated body obtained by carrying out sheet shaping | molding of the obtained dielectric ceramic composition was laminated | stacked, and it pressed after that, and produced the sheet | seat laminated molded object. Each dielectric ceramic was obtained from this sheet laminated molded body in the same manner as in Example 1. Each of Mg ₂ SiO ₄ contained as a main component of the produced dielectric ceramic, ZnO, B ₂ O ₃ , CaCO ₃ , SiO ₂ —BaO—CaO—Li ₂ O-based glass and LiO ₂ contained as subcomponents. Table 1 shows the blending amount.

<Evaluation>
Sintering density ρs of the obtained dielectric ceramic, relative density (100% when the sintering density is 3.35 g / cm ³ ), Q value, bending strength, deformation and sinterability of substrate, Each amount of ZnO relative to the phase was determined.

[Measurement of sintering density ρs]
The test piece after firing is cut and processed so as to be around 4.5 × 3.2 × 0.8 mm in the LWT direction, the dimensions in each direction are measured with a micrometer, the mass is measured with an electronic balance, and from there The bulk density was defined as the sintered density ρs (unit: g / cm ³ ). The measurement results are shown in Table 1. In this example, Mg ₂ SiO ₄ which is a main component of the dielectric ceramic composition used in manufacturing the dielectric ceramic of Example 4, and ZnO, B ₂ O ₃ and CaCO ₃ which are subcomponents are used. When the sintering density ρs was measured while changing the firing temperature and time of the dielectric ceramic composition having the same composition as the SiO ₂ —BaO—CaO—Li ₂ O-based glass, the value of the sintering density ρs was It was 3.35 g / cm ³ . Therefore, the value 3.35 g / cm ³ of the sintering density in Example 4 was defined as a relative density of 100%, and when the relative density was less than 96%, it was evaluated that the sintering was insufficient.

[Q value]
(Identification of the amount of unreacted ZnO by X-ray diffraction)
The calcined sample was ground into a powder using an agate mortar and XRD measurement was performed by X-ray diffraction spectroscopy (XRD) to measure the X-ray diffraction peak intensity. XRD measurement was performed using an X-ray diffractometer (trade name: RINT2000 / PC, manufactured by Rigaku Corporation) using a Cu tube. Example 4 and Comparative Example 7 were used as measurement samples. The measurement conditions were as follows. The X-ray diffraction charts of Example 4 and Comparative Example 7 are shown in FIG.
(Measurement condition)
・ Voltage: 50kV
・ Current: 300mA
・ Scanning speed: 4 ° / min
Range: 2θ = 10-70 (deg)

As shown in FIG. 4, from the XRD measurement results, in Example 4, the X-ray diffraction peak intensity was confirmed around 36.5 °, and in Comparative Example 7, the X-ray diffraction peak intensity I _A was around 36.4 °. Was confirmed. This X-ray diffraction peak intensity I _A is found due to the main phase Mg ₂ SiO ₄ . In Comparative Example 7, X-ray diffraction peak intensities I _B were confirmed at around 31.8 ° and around 33.6 °. This X-ray diffraction peak intensity I _B is found due to ZnO remaining unreacted. On the other hand, in Example 4, the X-ray diffraction peak intensity I _B was not confirmed in the vicinity of 31.8 ° and 33.6 °. Therefore, in a dielectric ceramic containing Mg ₂ SiO ₄ as a main component and ZnO, B ₂ O ₃ , CaCO _3, and SiO ₂ —BaO—CaO—Li ₂ O glass as subcomponents, the X-ray diffraction peak intensity I peak intensity ratio I _B / I _a of the X-ray diffraction peak intensity I _B for _a was 0%. _Meanwhile, a main component Mg 2 SiO _4, the dielectric ceramic containing ZnO and B ₂ O ₃ and CaCO ₃ and Li ₂ O as an auxiliary component, the peak intensity ratio I _B / I _A was about 15% . Therefore, like the dielectric ceramic of Example 4, Mg ₂ SiO ₄ is the main component, and ZnO, B ₂ O ₃ , CaCO _3, and SiO ₂ —BaO—CaO—Li ₂ O-based glass are included as subcomponents. In dielectric ceramics, zinc oxide does not exist unreacted and can be said to be completely reacted.

(Measurement of Q value)
The Q value was measured by the cavity resonator perturbation method. A test piece having a size of 0.8 mm square was inserted into the cavity resonator, and the change in the Q value in the cavity resonator was measured. The measurement frequency was 1.9 GHz, and the Q value was the average value of the Q values obtained three times. The measurement results are shown in Table 1.

[Measurement of bending strength]
The test pieces of each dielectric ceramic were cut so that the thickness was about 0.4 mm and the width was about 2.6 mm, and the three-point bending strength was measured. Three-point bending strength was measured using a measuring instrument (trade name: 5543, manufactured by Instron). The bending strength was determined from the results obtained by measurement by a three-point bending strength test. The jig distance between the two points that support the test piece at the time of measurement is 15 mm, the measurement speed is 0.5 mm / min, the measurement is performed at 10 points, and the average value of the values obtained by measuring 10 tests ( The unit was MPa). The measurement results are shown in Table 1.

[Deformation and sintering of substrate]
The deformation of the substrate was visually determined for each sample used for measuring the sintered density ρs. For sinterability, each sample used for the measurement of the sintered density ρs was broken, and the surface was observed with a scanning electron microscope (Scanning Electron Microscope, trade name: JSM-6700, manufactured by JEOL Datum) by SEM. It was judged whether or not the sinterability was sufficient with the degree of pore amount for a sample having a relative density of 100%. The results are shown in Table 1.

[Amount of unreacted ZnO remaining in the main phase]
The amount of ZnO remaining unreacted with respect to the main phase after calcination is the X-ray diffraction peak intensity I _A when 2θ of Mg ₂ SiO ₄ contained in the main phase is between 36.0 ° and 37.0 °, X-ray diffraction peak intensities I _B when 2θ of ZnO present in the reaction is 31.0 ° to 32.0 ° and 33.0 ° to 34.0 ° are obtained, and X-rays with respect to the X-ray diffraction peak intensities I _A It was determined from the peak intensity ratio I _B / I _{A of the} diffraction peak intensity I _B. The measurement results are shown in Table 1. The peak intensity ratio I _B / I _A was set to a suitable range of 10% or less.

As shown in Table 1, in Examples 1 12, the value of the sintered density ρs is in the range of ± 0.02 g / cm ³ from 3.35 g / cm ^3, the value of the sintered density ρs is 3. It was confirmed that the relative density value was 99% or more when 35 g / cm ³ was defined as a relative density of 100%. At this time, each of the dielectric ceramics of Examples 1 to 12 had a Q value of 1000 or more, a bending strength of 280 MPa or more, and there was no deformation of the substrate, and the sinterability was good. confirmed. Further, it was confirmed that the amount of ZnO remaining unreacted with respect to the main phase after firing was 0%. Therefore, by adding Li-based glass such as SiO ₂ —BaO—CaO—Li ₂ O-based glass, the amount of unreacted ZnO can be suppressed, and the Q value can be increased to 1000 or more. It can be said.

In contrast, in Comparative Example 1 and Comparative Examples 3 to 6, it was confirmed that the value of the sintered density ρs was smaller than 3.35 g / cm ^{3 and} the value of the relative density was smaller than 96%. In particular, when the value of the relative density is 90% or more and less than 96%, the Q value and the bending strength are low, and the base material may not be deformed, but both are insufficiently sintered. Was confirmed (see Comparative Examples 3 and 4). Moreover, when the value of relative density was smaller than 90%, Q value and bending strength became impossible to measure, and it was confirmed that the sintering was insufficient (see Comparative Examples 5 and 6). At this time, it was confirmed that the amount of ZnO with respect to the main phase was 0%. This is presumably because the dielectric ceramic composition was insufficiently sintered and a dielectric ceramic could not be obtained. In Comparative Examples 2 and 7 to 10, the relative density value was 96% or more, but the Q value was low, and the amount of unreacted ZnO remaining in the main phase was 15% or more. confirmed. This is considered to be because when Li ₂ O is added, unreacted ZnO remains to some extent, and the Q value cannot be increased to 1000 or more. Therefore, it can be said that ZnO remains in the dielectric ceramic if the Q value is low even if the sintering density ρs is good.

Thus, all firing the ZnO contained in the dielectric ceramic composition, while the peak intensity ratio I _B / I _A of the dielectric ceramic 10% or less, the relative density by 96% or more, the resulting dielectric It has been found that the sinterability of the body porcelain can be secured, the bending strength can be maintained, the Q value can be increased, and the dielectric loss can be decreased.

  As described above, the dielectric porcelain, the dielectric porcelain manufacturing method and the electronic component according to the present invention can be used for LTCC because it can improve the dielectric characteristics while enabling low-temperature firing. It can be suitably used for a circuit board or the like.

DESCRIPTION OF SYMBOLS 10 LC filter 11 Dielectric layer 12 Coil 13-1 to 23-3 Capacitor pattern part 14 Via (via conductor)

Claims (7)

A main component including Mg ₂ SiO ₄ and a subcomponent including zinc oxide and a glass component;
In X-ray diffraction, the unreacted zinc oxide 2θ is 31 with respect to the X-ray diffraction peak intensity I _A between 26.0 and 37.0 ° of Mg ₂ SiO _{4 as} the main phase. with the peak intensity ratio of X-ray diffraction peak intensity I _B at 32.0 ° and 34.0 ° from 33.0 ° from .0 ° I _B / I _a is not more than 10%,
A dielectric ceramic having a relative density of 96% or more. The dielectric ceramic according to claim 1, wherein the glass component includes at least one glass containing Li ₂ O.   The dielectric ceramic according to claim 1, wherein a content of the zinc oxide is 10 parts by mass or more and 16 parts by mass or less. In producing a dielectric ceramic containing a main component containing Mg ₂ SiO ₄ and a subcomponent containing zinc oxide and a glass component,
A raw material powder of the raw material powder and silicon dioxide magnesium oxide mixed and heat-treated to prepare a Mg ₂ SiO ₄ crystal powder, the Mg ₂ to SiO ₄ crystal powder, the zinc oxide and a glass component as a subcomponent material powder And a dielectric porcelain composition production step of obtaining a dielectric porcelain composition,
Firing the dielectric ceramic composition at a temperature of 800 ° C. or higher and 1000 ° C. or lower in an oxygen atmosphere to obtain a sintered body,
In X-ray diffraction, unreacted zinc oxidation with respect to X-ray diffraction peak intensity I _{A when} 2θ of Mg ₂ SiO ₄ which is the main phase of the sintered body is between 36.0 ° and 37.0 ° The peak intensity ratio I _B / I _A of the X-ray diffraction peak intensity I _{B when} the 2θ of the object is 31.0 ° to 32.0 ° and 33.0 ° to 34.0 ° is 10% or less,
A method for manufacturing a dielectric ceramic, wherein the relative density is 96% or more. The method for manufacturing a dielectric ceramic according to claim 4, wherein the glass component includes at least one glass containing Li ₂ O.   The method for manufacturing a dielectric ceramic according to claim 4 or 5, wherein a content of the zinc oxide is 10 parts by mass or more and 16 parts by mass or less.   An electronic component comprising a dielectric layer made of the dielectric ceramic according to any one of claims 1 to 3.

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