JP2011230960A - Glass-ceramic, method for manufacturing the same, and dielectric glass-ceramic molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric material with a high dielectric constant ε and a small absolute value of a temperature characteristic τε, which can be used for purposes such as a circuit board material of a high-frequency electronic component.SOLUTION: A glass-ceramic is provided which contains, in mol%, 5-50% TiO, 3-50% SrO and 15-85% SiO, relative to the total amount of substances in a composition expressed in terms of oxides, and contains SrTiOcrystals and/or a solid solution thereof. The glass-ceramic preferably has a dielectric constant ε of ≥20, a Q value of >1,000 and an absolute value of a temperature characteristic τε of the dielectric constant ε of <300.

Description

  The present invention relates to a glass ceramic, a manufacturing method thereof, and a dielectric glass ceramic molded body.

  A dielectric material for a circuit board mounted on a small communication device or electronic device used in a high frequency band is required to be a low loss material having a large Q value and excellent high frequency transmission characteristics. In addition, in order to achieve high performance and miniaturization of electronic components such as circuit boards and capacitors, it is necessary to have a high dielectric constant ε in the used frequency band. However, generally, the higher the dielectric constant ε of the dielectric material, the worse the temperature characteristic τε of the dielectric constant ε. Therefore, development of a dielectric material having a high dielectric constant ε and a small absolute value of the temperature characteristic τε (that is, close to zero) has been demanded.

  As a dielectric material used for circuit boards and electronic components, proposals have been made to use glass ceramics (for example, Patent Documents 1 to 4). These proposals in Patent Documents 1 to 4 all mix glass powder and inorganic filler, and are molded and fired. Therefore, the denseness is low, and pores and voids are generated, resulting in a uniform material. There is a problem that the inorganic filler reacts with the glass and the desired dielectric constant ε and temperature characteristic τε cannot be obtained.

On the other hand, a dielectric material for capacitors in which BaTiO ₃ crystals are precipitated by applying heat treatment to glass has been proposed (for example, Patent Document 5). However, since glass has a positive temperature characteristic τε, BaTiO ₃ also has a positive temperature characteristic τε. Therefore, in the glass ceramic disclosed in Patent Document 5, the absolute value of the temperature characteristic τε is controlled to a small value. It is difficult.

JP 2004-339049 A JP 2007-217274 A JP 2003-192430 A Japanese Patent No. 3805173 Japanese Patent Laid-Open No. 5-50453

  The present invention has been made in view of the above circumstances, and provides a dielectric material having a high dielectric constant ε and a small absolute value of temperature characteristic τε that can be used for applications such as circuit board materials for high-frequency electronic components. For the purpose.

In order to solve the above problems, the present invention provides the following aspects (1) to (14).
(1) the total amount of substance of the oxide composition in terms of, TiO ₂ 5 to 50% by mole%
SrO 3-50%, and
SiO ₂ 15~85%
Glass ceramics containing SrTiO ₃ crystals and / or solid solutions thereof.

(2) The glass ceramic according to the above (1), further containing one or a combination of two or more alkali metal oxides in a mol% of 35% or less based on the total amount of the oxide-converted composition.

(3) The glass ceramic according to (1) or (2), which has an oxide equivalent composition and further contains CaO and / or BaO.

(4) The glass ceramic according to (3), wherein a part of Sr of the SrTiO ₃ crystal is substituted with Ca and / or Ba.

(5) Oxide equivalent composition, Al ₂ O ₃ component, ZrO ₂ component, ZnO component, Ln ₂ O ₃ component (where Ln is La, Gd, Sc, Y, Ce, Eu, Nd, Dy (1) to (4) containing at least one component selected from the group consisting of Nb ₂ O ₅ and Ta ₂ O _5. The glass ceramic according to any one of the above.

(6) The glass ceramic according to (5), wherein a part of Ti in the SrTiO ₃ crystal is substituted with one or more selected from the group consisting of Al, Zr, Nb, and Ta.

(7) Any one of (1) to (6) above, further containing 5% or less of As ₂ O ₃ component and / or Sb ₂ O ₃ component in mol% with respect to the total amount of the oxide-converted composition Glass ceramics described in 1.

(8) The molar ratio of the oxide conversion composition, wherein the ratio of the content of TiO _{2 to} the content of SrO (TiO ₂ / SrO) is 0.5 or more, according to any one of (1) to (7) Glass ceramics.

(9) The dielectric constant ε at 1 MHz is 20 or more, the Q value is greater than 1000, and the dielectric property is such that the absolute value of the temperature characteristic τε of the dielectric constant ε is less than 300 in the temperature range of 0 ° C. to 100 ° C. Glass ceramics in any one of said (1) to (8).

(10) The glass ceramic according to any one of (1) to (9), wherein the SrTiO ₃ crystal and / or a solid solution thereof is precipitated from the glass by heat-treating the glass.

(11) A dielectric glass-ceramic molded body made of the glass ceramic according to any one of (1) to (10).

A method for producing a glass ceramic according to any one of (1) to (10) above,
A melting step of mixing raw materials to obtain a melt;
A first cooling step for lowering the temperature of the melt to a crystallization temperature range;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A second cooling step of reducing the temperature to outside the crystallization temperature region to obtain a glass ceramic in which crystals are dispersed.

(13) The method for producing a glass ceramic according to any one of (1) to (10) above,
A melting step of mixing raw materials to obtain a melt;
A cooling step of cooling the melt to obtain glass;
A reheating step of raising the temperature of the glass to a crystallization temperature region;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A recooling step of reducing the temperature to outside the crystallization temperature region to obtain a glass ceramic in which crystals are dispersed.

(14) The glass ceramic manufacturing method according to (12) or (13), wherein the crystallization temperature region is 500 ° C. or higher and 1100 ° C. or lower.

Since the glass ceramic of the present invention contains SrTiO ₃ crystal having a negative temperature characteristic τε and / or a solid solution thereof in the glass of the base material having a positive temperature characteristic τε of the dielectric constant ε, the absolute value of the temperature characteristic τε The value can be controlled to be small (close to zero). Therefore, the glass ceramic of the present invention can be used for electronic parts such as circuit boards as a dielectric material having a small absolute value of the temperature characteristic τε while maintaining a high dielectric constant ε and Q value.

In addition, the glass ceramic of the present invention has SrTiO ₃ crystals and / or solid solutions thereof precipitated from the glass by heat-treating the glass. While reducing the number of processes, it is possible to produce a dielectric material that is less likely to generate pores and voids, is uniform and dense, and has excellent durability.

3 is an XRD pattern of the glass ceramic obtained in Example 10. FIG.

The glass ceramic of the present invention contains 5 to 50% of TiO ₂ , 3 to 50% of SrO, and 15 to 85% of SiO ₂ with respect to the total amount of the oxide-converted composition. Furthermore, it contains SrTiO ₃ crystals and / or solid solutions thereof. In addition, in this specification, unless there is particular notice, content of each component which comprises glass ceramics shall be displayed by mol% with respect to the total amount of substances of an oxide conversion composition. Here, the “oxide equivalent composition” is assumed when oxides, composite salts, metal fluorides, etc. used as raw materials of the constituent components of the glass ceramic of the present invention are all decomposed and transformed into oxides when melted. In addition, the total amount of the generated oxide is 100 mol%, and each component contained in the glass is described.

The TiO ₂ component is a component that lowers the expansion of the glass, and when the glass is heat-treated, it is precipitated from the glass as SrTiO ₃ crystals and / or a solid solution thereof, and increases the dielectric constant ε and Q value of the glass ceramic. Further, since the SrTiO ₃ crystal has a negative temperature characteristic τε, the SrTiO ₃ crystal is precipitated in the glass of the base material having the positive temperature characteristic τε, so that the temperature characteristic of the dielectric constant ε of the glass ceramics. The absolute value of τε can be controlled to be small (close to zero). However, if the content of the TiO ₂ component is less than 5%, it becomes difficult to precipitate a sufficient amount of SrTiO ₃ crystals. Therefore, the lower limit of the content of the TiO ₂ component with respect to the total amount of the oxide-converted composition can be 5%, preferably 8%, more preferably 10%. On the other hand, if the content of the TiO ₂ component is too large, vitrification becomes difficult, so the upper limit can be 50%, preferably 45%, more preferably 40%. TiO ₂ component may be incorporated in the glass ceramics used as the starting material for example TiO ₂ or the like.

The SrO component is a component that improves the meltability and stability of the glass, and is deposited from the glass as a SrTiO ₃ crystal and / or its solid solution by heat treating the glass, and the dielectric constant ε and Q value of the glass ceramic To increase. Since the SrTiO ₃ crystal has a negative temperature characteristic τε, by precipitating the SrTiO ₃ crystal in the glass of the base material having the positive temperature characteristic τε, the temperature characteristic τε of the dielectric constant ε of the glass ceramic is obtained. The absolute value can be controlled to be small (close to zero). However, if the content of the SrO component is less than 3%, it becomes difficult to precipitate a sufficient amount of SrTiO ₃ crystals. Therefore, the lower limit of the content of the SrO component with respect to the total amount of the oxide-converted composition can be 3%, preferably 5%, more preferably 7%. On the other hand, if the content of the SrO component is too large, vitrification becomes difficult, so the upper limit can be 50%, preferably 45%, more preferably 40%. The SrO component can be introduced into the glass ceramic using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

From the viewpoint of keeping the temperature characteristic τε low while maintaining the dielectric constant ε high, the glass ceramic of the present invention has a molar ratio of TiO ₂ to SrO (TiO ₂₎ to promote crystallization of the SrTiO ₃ crystal and / or its solid solution. ₂ / SrO ratio) is preferably 0.50 or more, more preferably 0.75 or more, and preferably 0.90 or more. If the TiO ₂ / SrO ratio is less than 0.5, it may be difficult to crystallize the SrTiO ₃ crystal and / or its solid solution.

SiO ₂ component constitutes the network structure of glass and is a component for enhancing the stability and chemical durability of the glass. However, when the content of the SiO ₂ component is too large, crystals other than the intended SrTiO ₃ crystal are precipitated, and the performance as a dielectric becomes unstable. Therefore, the upper limit of the content of the SiO ₂ component with respect to the total amount of the oxide-converted composition can be 85%, preferably 60%, more preferably 50%. If the content of SiO ₂ component is too small, devitrification is likely to occur. Therefore, the lower limit of the content of the SiO ₂ component with respect to the total amount of the oxide conversion composition can be 15%, preferably 20%, more preferably 25%. SiO ₂ component may be incorporated in the glass ceramic is used as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

It is preferable that the glass ceramic of this invention contains the 1 type, or 2 or more types of combination of the alkali metal oxide of 35% or less further by mol% with respect to the total amount of substances of an oxide conversion composition. Here, examples of the alkali metal include Li, Na, K, Rb, and Cs. Accordingly, examples of the alkali metal oxide include Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O. In the glass ceramic of the present invention, in particular, when the total amount of alkali metal oxides is 35% or less, the stability of the glass is improved, and SrTiO ₃ crystals are easily precipitated. Accordingly, the total amount of alkali metal oxides with respect to the total amount of substances in oxide equivalent composition is preferably 35%, more preferably 30%, and most preferably 25%.

Li 2 _O component improves the meltability and stability of glass is a component that hardly generated cracks in the glass ceramics after heat treatment, is a component that can be added optionally. In addition, the Li ₂ O component is a component that lowers the glass transition temperature to easily generate SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Furthermore, Li enters the SrTiO ₃ crystal and forms a solid solution. However, if the content of the Li ₂ O component exceeds 35%, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the Li ₂ O component with respect to the total amount of the oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. Li ₂ O component may be incorporated in the glass ceramic by using, for example, _Li 2 _CO 3 as a raw material, LiNO _3, LiF and the like.

Na 2 _O component improves the meltability and stability of glass is a component that hardly generated cracks in the glass ceramics after heat treatment, is a component that can be added optionally. Further, the Na ₂ O component is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Further, Na substitutes for a part of Sr in the SrTiO ₃ crystal and enters the Sr site to form a solid solution. However, when the content of the Na ₂ O component exceeds 35%, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the Na ₂ O component with respect to the total amount of oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. Na ₂ O component may be incorporated in the glass ceramic is used as a raw material for example _{Na 2 O, Na 2 CO 3} , NaNO 3, NaF, Na 2 S, the Na 2 SiF ₆ or the like.

K 2 _O component improves the meltability and stability of glass is a component that hardly generated cracks in the glass ceramics after heat treatment, is a component that can be added optionally. Further, the K ₂ O component is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Furthermore, K substitutes for a part of Sr in the SrTiO ₃ crystal and enters the Sr site to form a solid solution. However, if the content of the K ₂ O component exceeds 35%, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the K ₂ O component with respect to the total amount of the oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. K ₂ O component may be incorporated in the glass ceramic by using the raw material as for example _{K 2 CO 3, KNO 3,} KF, KHF 2, K 2 SiF 6 and the like.

The Rb ₂ O component is a component that improves the meltability and stability of the glass and makes it difficult to cause cracks in the glass ceramic after the heat treatment, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and lowers the heat treatment temperature. Furthermore, Rb substitutes for a part of Sr in the SrTiO ₃ crystal and enters the Sr site to form a solid solution. However, when the content of the Rb ₂ O component exceeds 35%, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the content of the Rb ₂ O component with respect to the total amount of the oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. The Rb ₂ O component can be introduced into the glass ceramic using, for example, Rb ₂ CO ₃ , RbNO ₃ or the like as a raw material.

Cs 2 _O component improves the meltability and stability of glass is a component that hardly generated cracks in the glass ceramics after heat treatment, is a component that can be added optionally. In addition, it is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and lowers the heat treatment temperature. However, when the content of the Cs ₂ O component exceeds 35%, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total amount of the oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. Cs ₂ O component may be incorporated in the glass ceramics used as the starting material for example _Cs 2 _{CO 3,} CsNO 3, and the like.

  The glass ceramic of the present invention preferably has an oxide equivalent composition and further contains CaO and / or BaO.

The CaO component has an effect of improving the meltability and stability of the glass, and can be optionally added. Further, the CaO component is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Furthermore, Ca substitutes a part of Sr of SrTiO ₃ crystal and enters the Sr site to form a solid solution. However, if the content of the CaO component is too large, the stability of the glass is worsened, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the CaO component with respect to the total amount of substances of the oxide conversion composition is preferably 35%, more preferably 30%, and most preferably 25%. The CaO component can be introduced into the glass ceramic using, for example, CaCO ₃ or CaF ₂ as a raw material.

The BaO component has an effect of improving the meltability and stability of the glass and can be optionally added. Further, the BaO component is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Further, Ba has an effect of replacing a part of Sr of the SrTiO ₃ crystal and entering the Sr site to form a solid solution and increase the dielectric constant ε. However, when the content of the BaO component exceeds 47%, it becomes difficult to precipitate SrTiO ₃ crystals. Therefore, the upper limit of the BaO component content is preferably 47%, more preferably 45%, and most preferably 40% with respect to the total amount of the oxide-converted composition. The BaO component can be introduced into the glass ceramic using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like as a raw material.

Further, the glass ceramic of the present invention has an oxide equivalent composition, and further includes an Al ₂ O ₃ component, a ZrO ₂ component, a ZnO component, and an Ln ₂ O ₃ component (wherein Ln is La, Gd, Sc, Y, Ce). , Eu, Nd, Dy, Yb, Lu)), one or more components selected from the group consisting of Nb ₂ O ₅ and Ta ₂ O ₅ preferable. Furthermore, in the glass ceramic of the present invention, it is preferable that a part of Ti of the SrTiO ₃ crystal is substituted with one or more elements selected from the group consisting of Al, Zr, Nb and Ta.

Al ₂ O ₃ component increases the stability of the glass and the weather resistance of the glass ceramic, promotes the precipitation of SrTiO ₃ crystals from the glass, and Al enters the Ti sites of the SrTiO ₃ crystals to form a solid solution, resulting in a dielectric constant. It is a component that contributes to the improvement of ε and can be added arbitrarily. However, when there is too much the content, melt | dissolution temperature will raise remarkably and it will become difficult to vitrify. Therefore, when the Al ₂ O ₃ component is added, the content of the Al ₂ O ₃ component is preferably 20%, more preferably 15%, and most preferably 10% with respect to the total amount of the oxide-converted composition. To do. The Al ₂ O ₃ component can be introduced into the glass ceramic using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The ZrO ₂ component is a component that enhances the weather resistance of the glass ceramic and contributes to the improvement of the dielectric constant ε by the solid solution of Zr ions in the SrTiO ₃ crystal, and can be optionally added. However, when the content of the ZrO ₂ component is too large, vitrification becomes difficult. Therefore, the upper limit of the content of the ZrO ₂ component with respect to the total amount of substances of the oxide conversion composition is preferably 10%, more preferably 7%, and most preferably 5%. The ZrO ₂ component can be introduced into glass ceramics using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

A ZnO component is a component which improves the meltability and stability of glass, and improves the weather resistance of glass ceramics, and can be added arbitrarily. In addition, the ZnO component is a component that lowers the glass transition temperature to facilitate the formation of SrTiO ₃ crystals and suppresses the heat treatment temperature to a lower level. Furthermore, Zn substitutes for a part of Ti in the SrTiO ₃ crystal and enters the Ti site to form a solid solution. However, when the content of the ZnO component is too large, the stability of the glass is deteriorated, and the precipitation of SrTiO ₃ crystals becomes difficult. Therefore, the upper limit of the content of the ZnO component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 35%, and most preferably 30%. ZnO component may be introduced into the glass ceramic is used as a raw material for example ZnO, the ZnF _2, and the like.

The Ln ₂ O ₃ component (wherein Ln means at least one selected from the group consisting of La, Gd, Sc, Y, Ce, Eu, Nd, Dy, Yb and Lu) is mainly glass ceramics It is a component that enhances the weather resistance of, and can be optionally added. In particular, La, Ce, and Eu substitute for a part of Sr in the SrTiO ₃ crystal to enter the Sr site, and Sc substitutes a part of Ti to enter the Ti site to form a solid solution. However, if the total content of the Ln ₂ O ₃ components is too large, the stability of the glass is deteriorated. Accordingly, the total amount of the Ln ₂ O ₃ component with respect to the total amount of substances in the oxide conversion composition is preferably 30%, more preferably 20%, and most preferably 15%. The Ln ₂ O ₃ component includes, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Sc as raw materials. ₂ O ₃ , CeO ₂ , CeF ₃ , Eu ₂ O ₃ , Nd ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O _3, etc. can be used for introduction into the glass ceramic.

The Nb ₂ O ₅ component is a component that increases the meltability and stability of the glass and increases the dielectric constant ε of the glass ceramic, and forms a solid solution by Nb entering the Ti site of the SrTiO ₃ crystal instead of Ti. It is a component that can be optionally added. However, when the content of Nb ₂ O ₅ component is too large, stability of the glass is deteriorated. Therefore, the upper limit of the content of the Nb ₂ O ₅ component with respect to the total amount of substances in oxide equivalent composition is preferably 35%, more preferably 25%, and most preferably 20%. The Nb ₂ O ₅ component can be introduced into the glass ceramic using, for example, Nb ₂ O ₅ as a raw material.

The Ta ₂ O ₅ component is a component that increases the meltability and stability of the glass, increases the dielectric constant ε of the glass ceramic, and forms a solid solution when Ta enters the Ti site of the SrTiO ₃ crystal instead of Ti. Yes, a component that can be optionally added. However, when the content of Ta ₂ O ₅ component is too large, stability of the glass is deteriorated. Therefore, the upper limit of the content of the Ta ₂ O ₅ component with respect to the total amount of the oxide-converted composition is preferably 30%, more preferably 20%, and most preferably 10%. The Ta ₂ O ₅ component can be introduced into glass ceramics using, for example, Ta ₂ O ₅ as a raw material.

The glass ceramics of the present invention, the total amount of substance of the oxide composition in terms preferably contains As ₂ O ₃ component and / or Sb ₂ O ₃ component of 5% or less by mol%.

The As ₂ O ₃ component and / or the Sb ₂ O ₃ component are components that clarify and degas the glass, and can be optionally added. However, if the content of these components exceeds 5% in total, the stability of the glass will deteriorate. Accordingly, the total content of the As ₂ O ₃ component and / or Sb ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 5%, more preferably 3%, and most preferably 1%. To do. As ₂ O ₃ component and Sb ₂ O ₃ component are, for example, As ₂ O ₃ , As ₂ O ₅ , Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O and the like as raw materials. And can be introduced into glass ceramics.

Further, the glass ceramic of the present invention further includes Ga ₂ O ₃ component, HfO ₂ component, and M _x O _y component (wherein M is V, Cr, Mn, Fe, Co, etc.) as components forming SrTiO ₃ solid solution crystal. One or more selected from the group consisting of Ni and Cu, and x and y are each selected from the group consisting of x: y = 2: the smallest natural number satisfying (the valence of M)) One or more selected from the group consisting of GeO ₂ , TeO ₂ , B ₂ O ₃ , SnO, WO ₃ , Bi ₂ O ₃ as a component for improving glass stability or weather resistance These components may be contained.

  In the glass ceramic of the present invention, as components other than the above components, for example, non-metallic element components such as F component, Cl component and Br component, and metal elements such as Cu component, Ag component, Au component, Pd component and Pt component Components and other components can be added as necessary within the range not impairing the properties of the glass ceramic. However, lead compounds such as PbO, and components of Th, Cd, Tl, Os, Se, and Hg tend to refrain from being used as harmful chemical substances in recent years. Environmental measures are required until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the glass ceramics are substantially free of substances that pollute the environment. Therefore, the glass ceramics can be manufactured, processed, and discarded without taking any special environmental measures.

Since the composition of the glass ceramic of the present invention is expressed in mol% with respect to the total amount of the oxide-converted composition, it cannot be expressed directly in mass%. However, the composition expressed by mass% of each component present in the composition satisfying various properties required in the present invention generally takes the following values in terms of oxide.
TiO ₂ component 5-50% by mass
SrO component 4 to 70% by mass and / or SiO ₂ component 15 to 70% by mass
Li ₂ O component 0-20% by mass and / or Na ₂ O component 0-25% by mass and / or K ₂ O component 0-35% by mass and / or Rb ₂ O component 0-40% by mass and / or Cs ₂ O component 0 to 45% by mass and / or CaO component 0 to 30% by mass and / or BaO component 0 to 50% by mass and / or Al ₂ O ₃ component 0 to 20% by mass and / or ZrO ₂ component 0 to 14% by mass % And / or ZnO component 0-25 mass% and / or Ln ₂ O ₃ component 0-50 mass% in total and / or Nb ₂ O ₅ component 0-40 mass% and / or Ta ₂ O ₅ component 0-40 Mass% and / or As ₂ O ₃ component and Sb ₂ O ₃ component 0 to 3 mass% in total

The glass ceramic of the present invention having the above-described raw glass composition has a perovskite structure SrTiO ₃ crystal and / or a solid solution (Sr _1-x Ca _x ) TiO ₃ crystal, (Sr _1-x Ba _x ) in the crystal phase. ) TiO _{3 crystal, Sr (Ti 1-y Al} y) O 3 _{crystals, Sr (Ti 1-y Zr} y) O 3 _{crystals, Sr (Ti 1-y Nb} y) O 3 crystals, Sr _{(Ti 1-y} Ta _y ) O ₃ crystal or the like can be contained (however, 0 <x <1, 0 <y <1). Since these crystals have a negative temperature characteristic τε, the absolute value of the temperature characteristic τε of the dielectric constant ε of the glass ceramic can be controlled to be small (close to zero).

  Further, the crystallization rate of the glass ceramic of the present invention is preferably 1%, more preferably 2%, most preferably 3% in the volume ratio, preferably 85%, more preferably 83%, most preferably 3%. The upper limit is 80%. When the crystallization rate is 1% or more, the dielectric constant ε of the glass ceramic is improved, and the temperature characteristic τε can be brought close to zero, and the dielectric ceramic has good dielectric properties. On the other hand, when the crystallization rate is 85% or less, the glass ceramic has good mechanical strength.

  The size of the crystal is preferably 10 to 100 nm in average diameter when approximated to a sphere in order to obtain good dielectric properties. By controlling the heat treatment conditions, the size of the precipitated crystals can be controlled. The crystal grain size and the average value can be estimated from Scherrer's formula from the half width of the XRD diffraction peak. If the diffraction peaks are weak or overlap, measure the diameter of the crystal particle area measured using a scanning electron microscope (SEM) or transmission electron microscope (TEM), assuming that this is a circle. it can. When calculating an average value using a microscope, it is preferable to measure 100 or more crystal diameters at random.

  The glass ceramic of the present invention preferably has a dielectric constant (relative dielectric constant) ε at 1 MHz in the range of 20 to 35. When the dielectric constant ε is less than 20, it is difficult to reduce the size and performance of a circuit board or electronic component. If the dielectric constant ε is 20 or more (preferably 20 to 35), glass ceramics can be used as a capacitor. Therefore, when the glass ceramic of the present invention is used as a circuit board material, it can function as a capacitor. it can.

  Further, the glass ceramic of the present invention has a Q value (1 / tan δ; where tan δ is a dielectric loss tangent) at 1 MHz is greater than 1000, and preferably within a range of greater than 1250. When the Q value is 1000 or less, the dielectric loss increases, the high-frequency transmission characteristics deteriorate, and the electronic device cannot be reduced in size.

  Further, the glass ceramic of the present invention has an absolute value of a temperature characteristic (temperature dependence; ppm / ° C.) τε of a dielectric constant ε of less than 300 in a temperature range of 0 ° C. to 100 ° C., preferably 0 to 250. Is within the range. When the absolute value of the temperature characteristic τε exceeds 300, for example, when the glass ceramic of the present invention is used as a circuit board material, the capacitance of the board may change due to a temperature change.

  The glass ceramic of the present invention can be used as a dielectric glass ceramic molded body by processing into an arbitrary shape. Such a dielectric glass-ceramic molded body can be preferably used for high-frequency electronic components such as circuit boards, capacitors and resistors. For example, a high-frequency circuit board can be produced by using a dielectric glass-ceramic molded body as a circuit board, forming a wiring pattern thereon, and mounting necessary components. Further, the substrate made of the dielectric glass-ceramic molded body can be a multilayer substrate by laminating a plurality of layers.

[Glass ceramic production method]
Next, the glass ceramic production method of the present invention will be described by illustrating the first method and the second method. However, the method for producing the glass ceramic of the present invention is not limited to the following first method and second method.

<First method>
The first method is a melting step in which raw materials are mixed to obtain the melt, a first cooling step in which the melt temperature is lowered to the crystallization temperature region, and the melt temperature is maintained in the crystallization temperature region. And a second cooling step of obtaining a glass ceramic in which the crystal is dispersed by lowering the temperature of the melt to outside the crystallization temperature range.

(Melting process)
The melting step is a step of obtaining a melt by mixing raw materials having the above-described composition. More specifically, the raw materials are prepared so that each component of the glass ceramic is within a predetermined content range, mixed uniformly, and the prepared mixture is put into a platinum crucible, quartz crucible or alumina crucible. Melt in a temperature range of 1200 to 1600 ° C. for 1 to 24 hours in an electric furnace or combustion furnace, and homogenize with stirring to prepare a melt. The conditions for melting the raw material are not limited to the above temperature range, and can be appropriately set according to the composition and blending amount of the raw material composition.

(First cooling process)
In the first cooling step, the temperature of the melt is lowered to the crystallization temperature region and vitrified. Here, the conditions for vitrification are not particularly limited, and may be appropriately set according to the composition and amount of the raw material. In addition, the shape of the glass body obtained in this step is not particularly limited, and cooling may be performed by pouring into a mold, and plate drawing or the like may be performed as necessary.

(Crystallization process)
In the crystallization process, by maintaining the temperature of the glass body within the crystallization temperature region, crystals such as SrTiO ₃ crystals having a desired size from nano to micron are dispersed uniformly within the glass body. it can. The crystallization temperature region is, for example, a temperature region exceeding the glass transition temperature, and the glass transition temperature varies depending on the glass composition. Therefore, it is preferable to set the crystallization temperature according to the glass transition temperature. The lower limit of the crystallization temperature region is preferably 500 ° C., more preferably 550 ° C., and most preferably 580 ° C. On the other hand, if the crystallization temperature is too high, the glass phase is deformed, and the tendency to deposit an unknown phase other than the target becomes strong, and desired dielectric properties cannot be obtained. Therefore, the upper limit of the crystallization temperature region is 1100 ° C. Preferably, 1050 ° C is more preferable, and 1000 ° C is most preferable. Accordingly, although it varies depending on the glass composition, the crystallization temperature region is preferably 500 ° C. or higher and 1100 ° C. or lower, more preferably 550 ° C. or higher and 1050 ° C. or lower, and 580 ° C. or higher and 1000 ° C. or lower. Is most preferred. The holding time in the crystallization temperature region can be, for example, 1 to 48 hours.

(Second cooling step)
In the second cooling step, glass melt in which crystals are dispersed is obtained by lowering the temperature of the melt to outside the crystallization temperature range (for example, room temperature). If the cooling rate is too high, the glass ceramics may be damaged due to the difference in thermal expansion between the precipitated crystal phase and the glass matrix phase. Therefore, the cooling rate is preferably 1200 K / hr or less, more preferably 600 K / hr or less, and 300 K / Most preferred is hr or less. In particular, when the glass body has a large diameter, it is slowly cooled as necessary.

<Second method>
The second method includes a melting step of mixing raw materials to obtain the melt, a cooling step of cooling the melt to obtain glass, a reheating step of raising the glass temperature to the crystallization temperature range, and glass A crystallization step for generating crystals by maintaining the temperature in the crystallization temperature region, and a recooling step for reducing the temperature of the glass to outside the crystallization temperature region to obtain glass ceramics in which the crystals are dispersed. Can do. Note that description of steps similar to those of the first method is omitted as appropriate.

  The melting step can be performed in the same manner as in the first method.

(Cooling process)
The cooling step is a step of producing glass by cooling and vitrifying the melt obtained in the melting step. Specifically, a vitrified glass body is formed by flowing out the melt and appropriately cooling it. Here, the conditions for vitrification are not particularly limited, and may be appropriately set according to the composition and amount of the raw material. Moreover, the shape of the glass body obtained at this process is not specifically limited, Although it may be plate shape, a granular form, etc., it is preferable that it is plate shape at the point which can produce a glass body rapidly and in large quantities. Since devitrification occurs when the cooling rate is low, the cooling rate from the melting temperature to the yield point is preferably 100 K / min or more. Moreover, if the strain removal is necessary, the strain may be removed by holding at a temperature between the yield point and the glass transition point for 1 minute or more.

(Reheating process)
The reheating step is a step of raising the temperature of the glass body obtained in the cooling step to the crystallization temperature region. The temperature in the crystallization temperature region is the same as in the first method. In this step, the temperature increase rate and temperature have a great influence on crystal formation and crystal size, so it is important to precisely control them. The temperature range at which nucleation and nucleation are activated is different, and the type, size, number, amount, etc. of crystals can be controlled by the holding time of each, and the heating rate is appropriately changed according to the desired physical properties be able to. Moreover, you may change a temperature increase rate in a reheating process.

(Crystallization process)
The crystallization step is a step of generating crystals such as SrTiO ₃ crystals by maintaining the temperature of the glass body within a crystallization temperature region for a predetermined time. By holding in the crystallization temperature region for a predetermined time in this crystallization step, crystals such as SrTiO ₃ crystals having a desired size from nano to micron units can be uniformly dispersed inside the glass body. In this step, the rate of temperature increase and the temperature greatly affect the size of the crystal, so it is important to appropriately control according to the composition and the heat treatment temperature. The heat treatment time for crystallization needs to be set under conditions that allow crystals to grow to a certain extent and precipitate a sufficient amount of crystals according to the glass composition, heat treatment temperature, and the like. The heat treatment time can be set in various ranges depending on the crystallization temperature. If the rate of temperature increase is slow, it may be sufficient to heat only to the heat treatment temperature. However, as a guideline, it is preferable to set the heat treatment time short when the temperature is high and set the heat treatment time long when the temperature is low. The crystallization process may be a one-step heat treatment, or may undergo a two-step or more heat treatment process.

(Recooling process)
The recooling step is a step of obtaining a crystal-dispersed glass having SrTiO ₃ crystals and the like by lowering the temperature to outside the crystallization temperature region after crystallization is completed. If the cooling rate is too high, the glass ceramics may be damaged. Therefore, the cooling rate is preferably 1200 K / hr or less, more preferably 600 K / hr or less, and most preferably 300 K / hr or less.

  In the said 1st method and 2nd method, a shaping | molding process can be provided as needed and a glass or glass ceramics can be processed into arbitrary shapes. The forming step may be provided at the stage of the glass body or may be provided at the stage of the glass ceramic after crystallization.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by the following Examples.
Examples 1-14, Comparative Examples 1-5
Tables 1 to 3 show the glass compositions of the raw materials of Examples 1 to 14 and Comparative Examples 1 to 5 of the present invention, the heat treatment (crystallization) conditions, and the types of main crystal phases deposited on these glasses. The glass ceramics (or glasses) of Examples 1 to 14 and Comparative Examples 1 to 5 are all equivalent oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and metaphosphoric acids as raw materials for each component. High purity raw materials used for ordinary glass such as compounds were selected and used. These raw materials were weighed so as to have the composition ratios of the respective examples shown in Tables 1 to 3 and mixed uniformly, and then charged into a platinum crucible, and an electric furnace according to the melting difficulty of the glass composition. It melt | dissolved for 1 to 24 hours in the temperature range of 1200 to 1600 degreeC, and homogenized with stirring, and foaming etc. were performed. Thereafter, the temperature was lowered to 1500 ° C. or lower, and the mixture was homogenized with stirring, cast into a mold, and gradually cooled to produce glass. About the obtained glass, it heated to the crystallization temperature described in each Example of Tables 1-3, and the comparative example, and was hold | maintained for the described time, and crystallized (however, Comparative Examples 1-3 is No crystallization treatment was performed). Then, it cooled from the crystallization temperature and obtained the glass ceramic which has the target crystal phase. Here, the types of precipitated crystal phases of the glass ceramics of the examples and comparative examples were identified by an X-ray diffractometer (manufactured by Philips, trade name: X′Pert-MPD).

  Tables 1 to 3 show the temperature characteristics τε of the dielectric constant ε, Q value, and dielectric constant ε at 1 MHz of the obtained glass ceramics or glass. Moreover, the XRD pattern of the glass ceramic of Example 10 was shown typically in FIG.

Since the glass ceramics of Examples 1 to 14 can suppress the absolute value of the temperature characteristic τε of the dielectric constant ε to be small while maintaining a high dielectric constant ε and Q value, the dielectric material for circuit boards and electronic components is used. It was confirmed that it can be used as. Moreover, as illustrated in FIG. 1, the glass ceramics of the example contained SrTiO ₃ crystals precipitated from the glass. From the above, the glass ceramics of Examples 1 to 14 are homogeneous and dense dielectric materials that can be manufactured by heat treatment in the air atmosphere using glass as a raw material, and after mixing a metal oxide with glass powder. Compared to the conventional method of sintering in a reducing atmosphere or pressure adjustment conditions (pressurization or vacuum), it was also confirmed that it can be manufactured with simple equipment and processes.

On the other hand, Comparative Examples 1 to 3 are non-crystallized glasses, and Comparative Example 4 does not contain SrO and Paranite (Na ₂ TiSiO ₅ ) crystals are precipitated, both of which have low dielectric constant ε and Q value. confirmed. Further, in Comparative Example 5, Belcovite (Ba ₃ (Nb _4.8 , Ti _1.2 ) Si ₄ O _25.4 ) crystal was precipitated on the surface, but the inside was glass, and it was not suitable as a dielectric material. found.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment. Those skilled in the art can make many modifications without departing from the spirit and scope of the present invention, and these are also included within the scope of the present invention.

Claims (14)

TiO ₂ 5-50% in mol% with respect to the total amount of substances in oxide equivalent composition
SrO 3-50%, and
SiO ₂ 15~85%
Glass ceramics containing SrTiO ₃ crystals and / or solid solutions thereof.   The glass ceramic according to claim 1, further comprising one or a combination of two or more alkali metal oxides in an amount of 35% or less by mole% with respect to the total amount of the oxide-converted composition.   The glass ceramic according to claim 1 or 2, further comprising CaO and / or BaO in an oxide equivalent composition. The glass ceramic according to claim 3, wherein a part of Sr of the SrTiO ₃ crystal is substituted with Ca and / or Ba. It is an oxide conversion composition, and further includes an Al ₂ O ₃ component, a ZrO ₂ component, a ZnO component, and an Ln ₂ O ₃ component (wherein Ln is La, Gd, Sc, Y, Ce, Eu, Nd, Dy, Yb, _5. One or more components selected from the group consisting of Nb ₂ O ₅ and Ta ₂ O ₅ are contained in any one of claims 1 to 4. The glass ceramic described. The glass ceramic according to claim 5, wherein a part of Ti of the SrTiO ₃ crystal is substituted with one or more selected from the group consisting of Al, Zr, Nb, and Ta. The glass according to any one of claims 1 to 6, further comprising 5% or less of an As ₂ O ₃ component and / or an Sb ₂ O ₃ component in mol% with respect to the total amount of the oxide-converted composition. Ceramics. The glass ceramic according to any one of claims 1 to 7, wherein a ratio of the content of TiO _{2 to} the content of SrO (TiO ₂ / SrO) is 0.5 or more in terms of a molar ratio of an oxide equivalent composition.   The dielectric property ε at 1 MHz is 20 or more, the Q value is larger than 1000, and the dielectric property is such that the absolute value of the temperature characteristic τε of the dielectric constant ε is less than 300 in the temperature range of 0 ° C to 100 ° C. The glass ceramics according to any one of 1 to 8. The glass ceramic according to any one of claims 1 to 9, wherein the SrTiO ₃ crystal and / or a solid solution thereof is precipitated from the glass by heat-treating the glass.   A dielectric glass-ceramic molded body made of the glass-ceramic according to any one of claims 1 to 10. It is a manufacturing method of the glass ceramics according to any one of claims 1 to 10,
A melting step of mixing raw materials to obtain a melt;
A first cooling step for lowering the temperature of the melt to a crystallization temperature range;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A second cooling step of reducing the temperature to outside the crystallization temperature region to obtain a glass ceramic in which crystals are dispersed. It is a manufacturing method of the glass ceramics according to any one of claims 1 to 10,
A melting step of mixing raw materials to obtain a melt;
A cooling step of cooling the melt to obtain glass;
A reheating step of raising the temperature of the glass to a crystallization temperature region;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A recooling step of reducing the temperature to outside the crystallization temperature region to obtain a glass ceramic in which crystals are dispersed. The method for producing glass ceramics according to claim 12 or 13, wherein the crystallization temperature region is 500 ° C or higher and 1100 ° C or lower.

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