JP7348587B2 - glass ceramic dielectric - Google Patents

Description

The present invention relates to a glass ceramic dielectric used for circuit boards and the like.

Conventionally, glass ceramic dielectrics have been known as insulating materials for ceramic multilayer substrates, thick film circuit components, semiconductor packages, etc. on which ICs, LSIs, etc. are mounted with high density (see, for example, Patent Document 1). For example, metal wiring having a predetermined pattern is formed on the surface of a glass ceramic dielectric and used as a circuit board.

Japanese Patent Application Publication No. 10-120436

Metal wiring is usually formed by plating, but the plating may alter the glass components contained in the glass-ceramic dielectric, which may adversely affect properties such as dielectric constant and dielectric loss.

In view of the above, an object of the present invention is to provide a glass-ceramic dielectric whose surface can be plated without causing deterioration of the glass components.

The glass ceramic dielectric of the present invention is characterized by comprising a glass ceramic layer and a barrier layer formed on the main surface thereof. In this way, when metal wiring such as gold or silver is formed on the surface of the glass ceramic dielectric by plating, it is possible to suppress deterioration of the glass component contained in the glass ceramic layer.

In the glass ceramic dielectric of the present invention, barrier layers are preferably formed on both main surfaces of the glass ceramic layer. In this way, it is possible to suppress the occurrence of warpage due to the difference in coefficient of thermal expansion between the glass ceramic layer and the barrier layer in the firing process during production of the glass ceramic dielectric of the present invention.

In the glass ceramic dielectric of the present invention, the barrier layer is preferably made of an inorganic material. In this way, when the surface of the glass-ceramic dielectric is plated, it becomes easier to suppress the glass component contained in the glass-ceramic layer from deteriorating.

In the glass-ceramic dielectric of the present invention, the barrier layer is preferably made of amorphous glass. In this way, when the surface of the glass-ceramic dielectric is plated, it becomes easier to suppress deterioration of the glass component contained in the glass-ceramic layer.

In the glass-ceramic dielectric of the present invention, it is preferable that the amorphous glass contains 40% or more of SiO ₂ and 15% or less of B ₂ O ₃ in terms of glass composition by mass %. In this way, a barrier layer having excellent acid resistance can be obtained, so that the function as a barrier layer can be enhanced.

In the glass-ceramic dielectric of the present invention, the amorphous glass preferably does not substantially contain an alkali metal component. In this way, a barrier layer having excellent acid resistance can be obtained, so that the function as a barrier layer can be enhanced. Note that "substantially not containing an alkali metal component" means that the raw material does not intentionally contain an alkali metal component, and does not exclude the inclusion of unavoidable impurities. Objectively, it means that the content of the alkali metal component is less than 0.1% by mass.

In the glass-ceramic dielectric of the present invention, the glass-ceramic layer is preferably made of a sintered body of powder containing crystalline glass powder. Note that "crystalline glass powder" means glass powder that precipitates crystals by heat treatment. Here, "heat treatment" means to sufficiently advance crystallization at a temperature equal to or higher than the crystallization initiation temperature, and refers to, for example, heat treatment at 800 to 1000° C. for 20 minutes or more.

The glass-ceramic dielectric of the present invention has a crystalline glass powder having a glass composition in mass % of 20 to 65% of SiO ₂ , 3 to 25% of CaO, 7 to 30% of MgO, 0 to 20% of Al ₂ O ₃ , It is preferable that it contains 5 to 40% BaO and satisfies the relationship 1≦SiO ₂ /BaO≦4 in terms of mass ratio. The crystalline glass powder having the above composition has a property that feldspar crystals are precipitated together with diopside crystals (2SiO ₂ .CaO.MgO) as main crystals by heat treatment. By precipitating both crystals, the degree of crystallinity due to firing increases, and it is possible to reduce the residual glass phase that causes the dielectric constant and dielectric loss to increase. Further, since feldspar crystals have a small volumetric shrinkage rate during crystal precipitation, the generation of pores accompanying crystal precipitation is suppressed. As a result, it becomes possible to obtain a glass ceramic dielectric material with low dielectric constant and low dielectric loss.

In the glass-ceramic dielectric of the present invention, the glass-ceramic layer is preferably made of a sintered body of powder containing 30 to 100% by mass of crystalline glass powder and 0 to 70% by mass of filler powder. By making the glass-ceramic dielectric material a sintered body of powder containing filler powder in addition to crystalline glass powder, it is possible to improve the properties of the glass-ceramic dielectric material, such as its coefficient of thermal expansion, toughness, and dielectric constant. can.

In the glass ceramic dielectric of the present invention, the filler powder preferably contains an Al component. In this way, the Si and Ba components in the glass phase remaining after diopside crystal precipitation react with the Al component in the filler powder, making it easier to precipitate feldspar crystals.

In the glass ceramic dielectric of the present invention, the glass ceramic layer preferably contains diopside crystals and feldspar crystals. For the above-mentioned reasons, when both crystals are contained, a glass-ceramic layer with a high crystallinity and few pores can be easily obtained, and a glass-ceramic dielectric with a low dielectric constant and dielectric loss can be obtained.

The glass ceramic dielectric of the present invention is suitable for use in circuit boards.

The circuit board of the present invention is characterized in that metal wiring is formed on the surface of the barrier layer in the glass ceramic dielectric described above.

The method for manufacturing a glass-ceramic dielectric of the present invention is a method for manufacturing the above-mentioned glass-ceramic dielectric, which comprises: a green sheet for a glass-ceramic layer containing crystalline glass powder; and a green sheet containing amorphous glass powder. The present invention is characterized by comprising a step of preparing a green sheet for a barrier layer, a step of laminating a green sheet for a glass ceramic layer and a green sheet for a barrier layer to obtain a laminate, and a step of firing the laminate. Note that "amorphous glass powder" refers to glass powder that does not substantially precipitate crystals by heat treatment. "Substantially no crystals are precipitated" means that the crystallinity of the glass after heat treatment is approximately 1% or less, including the inevitable precipitation of devitrification substances.

According to the present invention, it is possible to provide a glass-ceramic dielectric whose surface can be plated without causing deterioration of glass components.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the glass ceramic dielectric of the present invention. 1 is a schematic cross-sectional view showing an embodiment of the method for manufacturing a glass ceramic dielectric of the present invention.

Embodiments of the glass ceramic dielectric of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the glass ceramic dielectric of the present invention. The glass-ceramic dielectric 1 includes a glass-ceramic layer 2 and barrier layers 3 formed on main surfaces 2a and 2b of the glass-ceramic layer 2, respectively. By plating the surface of the barrier layer 3 to form metal wiring (not shown), it can be used as a circuit board. If necessary, thermal vias or the like may be formed inside the glass ceramic layer 2. Note that the glass ceramic dielectric 1 is a plate-like member having a rectangular or circular planar shape.

By forming the barrier layer 3 on both main surfaces of the glass ceramic layer 2, warping caused by the difference in thermal expansion coefficient between the glass ceramic layer 2 and the barrier layer 3 can be prevented in the firing process during the production of the glass ceramic dielectric 1. The occurrence can be suppressed. Note that the barrier layer 3 does not necessarily need to be formed on both main surfaces of the glass ceramic layer 2, and the barrier layer 3 may be formed only on one main surface of the glass ceramic layer 2.

Each component will be explained in detail below.

(glass ceramic layer)
The glass-ceramic layer is made of a sintered body of powder containing, for example, crystalline glass powder. The crystalline glass powder contains, in terms of glass composition, 20 to 65% of SiO ₂ , 3 to 25% of CaO, 7 to 30% of MgO, 0 to 20% of Al ₂ O ₃ , and 5 to 40% of BaO. , and which satisfies the relationship 1≦SiO ₂ /BaO≦4 in terms of mass ratio. As mentioned above, the glass-ceramic dielectric obtained by firing the crystalline glass powder having the above composition has the property that feldspar crystals are precipitated together with diopside crystals as main crystals by heat treatment, and the dielectric constant and dielectric loss are This makes it possible to create a glass-ceramic dielectric with a low Specifically, at 25°C, the dielectric constant is 6 to 11, especially 6 to 10, and the dielectric loss tan δ in the high frequency region of 0.1 GHz or higher is 20 × 10 ^-4 or less, 18 × 10 ^-4 or less, especially 16 ×10 ⁻⁴ or less can be achieved.

Note that the feldspar crystal is preferably a barium feldspar crystal (BaAl ₂ Si ₂ O ₈ ). By precipitating barium feldspar crystals, the residual glass phase after heat treatment can be effectively reduced, making it easier to obtain a glass ceramic dielectric with low porosity and dielectric loss. In addition, calcium feldspar crystals (CaAl ₂ Si ₂ O ₈ ) or the like may be precipitated as long as the dielectric loss and porosity do not increase.

The reason why the composition of the crystalline glass powder was limited as described above will be described below. In addition, in the description of the content of each component below, "%" means "mass %" unless otherwise specified.

SiO ₂ is a glass network former and a constituent of diopside and feldspar crystals. The content of SiO ₂ is preferably 20-65%, 30-65%, particularly 40-55%. If the content of SiO ₂ is too small, it becomes difficult to vitrify, and if the content is too large, low-temperature firing (eg, 1000° C. or lower) tends to become difficult.

CaO is a constituent of diopside crystals, and its content is preferably 3 to 25%, 3 to 20%, particularly 7 to 15%. If the CaO content is too low, diopside crystals will be difficult to precipitate, and as a result, the dielectric loss of the glass ceramic dielectric will tend to increase. On the other hand, if the content of CaO is too high, the fluidity of the glass decreases, making it difficult to obtain a dense sintered body.

MgO is also a constituent of diopside crystals, and its content is preferably 7 to 30%, 8 to 30%, 11 to 30%, particularly 12 to 20%. If the content of MgO is too small, crystals will be difficult to precipitate, and if the content is too large, it will be difficult to vitrify.

Al ₂ O ₃ is a component for stabilizing glass, and its content is preferably 0 to 20%, 0.5 to 20%, particularly 1 to 10%. If the content of Al ₂ O ₃ is too high, it becomes difficult for diopside crystals to precipitate, and as a result, the dielectric loss of the glass ceramic dielectric tends to increase.

BaO is a constituent of barium feldspar crystals, and its content is preferably 5 to 40%, particularly 10 to 35%. If the BaO content is too low, barium feldspar crystals will be difficult to precipitate. On the other hand, if the BaO content is too high, the amount of diopside crystals precipitated tends to decrease, and as a result, the dielectric loss of the glass ceramic dielectric tends to increase.

Further, by limiting the ratio (mass ratio) of SiO ₂ and BaO to a specific range, feldspar crystals can be efficiently precipitated from the glass phase remaining after firing. Specifically, it is preferable to satisfy the relationship 1≦SiO ₂ /BaO≦4, particularly 1.05≦SiO ₂ /BaO≦3.95. If the ratio of SiO ₂ and BaO is out of this range, it becomes difficult for feldspar crystals to precipitate or vitrify.

In addition, the following components can be added to the crystalline glass powder.

ZnO is a component that facilitates vitrification, and its content is preferably 0 to 20%, particularly 0.1 to 15%. If the ZnO content is too high, the crystallinity tends to be weakened and the amount of diopside crystals precipitated tends to decrease. As a result, the dielectric loss of the glass-ceramic dielectric tends to increase.

TiO ₂ and ZrO ₂ are components that improve the chemical resistance (acid resistance, alkali resistance) of the glass ceramic dielectric. The content of TiO ₂ is preferably 0 to 15%, particularly 0.1 to 13%. If the content of TiO ₂ is too high, the dielectric loss of the glass-ceramic dielectric tends to become too large. The content of ZrO ₂ is preferably 0 to 15%, particularly 0.1 to 13%. Too much _ZrO2 tends to cause the dielectric loss of the glass-ceramic dielectric to become too large.

In addition to _the above _components , SrO, _{Nb2O5 , La2O3} , _{Y2O3 , P2O5} , _{B2O3 ,} Bi ₂ O ₃ , CuO, CeO ₂ , MnO, Sb ₂ O ₃ , SnO, etc. may be added in a total amount of up to 30%.

Note that alkali metal components such as Li ₂ O, Na ₂ O, and K ₂ O tend to cut the glass network and increase dielectric loss. Additionally, the insulation properties of the glass-ceramic dielectric tend to decrease. Therefore, the total amount of alkali metal oxides is preferably 5% or less, particularly 1% or less, and most preferably substantially not contained (specifically, less than 0.1%).

The average particle diameter _D50 of the crystalline glass powder is preferably 10 μm or less, particularly 5 μm or less. If the average particle diameter D ₅₀ of the crystalline glass powder is too large, pores are likely to occur in the glass ceramic dielectric. On the other hand, the lower limit of the average particle diameter D ₅₀ of the crystalline glass powder is not particularly limited, but from the viewpoint of ease of handling and processing cost, it is preferably 0.1 μm or more, particularly 1 μm or more. In addition, in this specification, the particle diameter of powder refers to the value measured by laser diffraction scattering method.

Note that, for the purpose of improving properties such as thermal expansion coefficient, toughness, and dielectric constant, a glass ceramic layer may be obtained by mixing filler powder in addition to crystalline glass powder and sintering the mixture. Examples of the filler powder include ceramic powders such as alumina powder, cordierite powder, mullite powder, quartz powder, zircon powder, titania powder, and zirconia powder, and quartz glass powder, which may be used alone or in combination of two or more. can be used.

In addition, by using a ceramic powder containing an Al component as a filler powder, the Si and Ba components in the glass phase remaining after diopside crystal precipitation react with the Al component in the ceramic powder to form feldspar crystals. It becomes easier to precipitate. Examples of ceramic powders containing an Al component include alumina powder, cordierite powder, mullite powder, anorthite feldspar, albite feldspar, barium aluminate, aluminum titanate, spinel, calcium aluminate, magnesium aluminate, aluminum nitride, etc. .

Further, by mixing a small amount (for example, about 0.1 to 1% by mass) of diopside or barium feldspar crystals as crystal nuclei, it is possible to improve the degree of crystallinity.

The mixing ratio of the crystalline glass powder and the filler powder is preferably 30 to 100% by mass of the crystalline glass powder and 0 to 70% by mass of the filler powder, 40 to 90% by mass of the crystalline glass powder and 10 to 60% by mass of the filler powder. It is more preferably 45 to 80 mass % for crystalline glass powder, 20 to 55 mass % for filler powder, and even more preferably 50 to 70 mass % for crystalline glass powder, and 30 to 50 mass % for filler powder. It is particularly preferable that there be. Too much filler powder content tends to make it difficult to densify the glass-ceramic dielectric.

The average particle diameter D ₅₀ of the filler powder is preferably 0.01 to 100 μm, 0.1 to 50 μm, 0.5 to 20 μm, particularly 1 to 10 μm. If the average particle diameter _D50 of the filler powder is too small, it will dissolve into the crystalline glass powder, making it difficult to obtain the effect of improving properties such as thermal expansion coefficient, toughness, dielectric constant, and chemical resistance. On the other hand, if the average particle diameter D ₅₀ of the filler powder is too large, it will hinder the flow of the crystalline glass powder during firing, and pores will easily occur in the glass-ceramic dielectric. In addition, by making the particle diameters of the crystalline glass powder and the filler powder close to each other, the dispersibility when the two are mixed becomes excellent, and a homogeneous glass ceramic dielectric material can be easily obtained. Furthermore, since the sinterability is improved, it becomes easier to obtain a dense glass ceramic dielectric.

By heat-treating a crystalline glass powder or a mixture of a crystalline glass powder and a filler powder at a temperature higher than the crystallization initiation temperature of the crystalline glass powder, a glass ceramic layer in which diopside crystals and feldspar crystals are precipitated as main crystals is formed. can get.

The content of diopside crystals in the glass ceramic layer is preferably 35% by mass or more, particularly 40% by mass or more. If the content of diopside crystals is too small, dielectric loss tends to increase. On the other hand, if the content of diopside crystals is too large, the number of pores in the glass ceramic layer increases, so the upper limit is preferably 80% by mass or less, particularly 70% by mass or less.

The content of feldspar crystals in the glass-ceramic layer is preferably 20 to 65% by weight, 25 to 60% by weight, particularly 30 to 55% by weight. If the content of feldspar crystals is too low, the porosity in the glass-ceramic layer tends to increase, resulting in increased dielectric loss. On the other hand, if the content of feldspar crystals is too high, the diopside crystals will be relatively small, which tends to increase dielectric loss and reduce mechanical strength.

In the glass-ceramic layer, the residual glass phase is preferably 0.5% by mass or more, particularly 1% by mass or more. If there is too little residual glass phase, pores are likely to occur in the glass ceramic layer. In addition, if the content of the residual glass phase is too large, the number of diopside crystals and feldspar crystals will decrease relatively, and the dielectric loss will tend to increase. Therefore, the upper limit is 20% by mass or less, especially 10% by mass or less. It is preferable that there be.

The glass ceramic layer preferably has a porosity of 3% by volume or less, particularly 2% by volume or less. When the porosity increases, when a glass ceramic dielectric is used as a circuit board, there is a tendency for wiring to be easily disconnected or for dielectric loss to increase.

The thickness of the glass ceramic layer is preferably adjusted appropriately within the range of, for example, 200 to 2000 μm, 300 to 1500 μm, or even 500 to 1000 μm so as to obtain the desired mechanical strength.

(barrier layer)
The barrier layer is preferably made of an inorganic material, particularly preferably amorphous glass. In this way, when the surface of the glass-ceramic dielectric is plated, it becomes easier to suppress the glass component contained in the glass-ceramic layer from deteriorating.

The barrier layer (amorphous glass layer) made of amorphous glass is made of, for example, a sintered body of amorphous glass powder. The amorphous glass (amorphous glass powder) preferably contains 40% or more of SiO ₂ and 15% or less of B ₂ O ₃ in terms of glass composition by mass %. The reason for limiting the glass composition in this manner will be described below. In addition, in the description of the content of each component below, "%" means "mass %" unless otherwise specified.

SiO ₂ is a component that forms a glass network. The content of SiO ₂ is preferably 40% or more, 42% or more, 45% or more, particularly 47% or more. If the content of SiO ₂ is too small, the acid resistance will be poor and the amorphous glass layer will have difficulty functioning as a barrier layer when forming metal wiring on the surface of the glass ceramic dielectric. In addition, if the content of SiO ₂ is too large, the sinterability will be poor, it will be difficult to obtain a dense amorphous glass layer, and the function as a barrier layer will tend to deteriorate. Therefore, the content of SiO ₂ is preferably 85% or less, 80% or less, 70% or less, particularly 60% or less.

B ₂ O ₃ is a component that lowers the melting temperature and significantly improves meltability, and also has the effect of improving the fluidity of glass powder during sintering to form an amorphous glass layer. However, if the content is too large, the acid resistance will be poor and the function of the amorphous glass layer as a barrier layer will tend to deteriorate. Therefore, the content of B ₂ O ₃ is preferably 15% or less, 12% or less, 10% or less, particularly 8% or less. In order to obtain the above effects of improving meltability and fluidity, the content of B ₂ O ₃ is preferably 1% or more, 2% or more, particularly 3% or more.

The amorphous glass layer can contain the following components in addition to the above components.

Al ₂ O ₃ is a component that improves the acid resistance of the amorphous glass layer. The content of Al ₂ O ₃ is preferably 0 to 25%, 0.1 to 20%, 1 to 15%, particularly 2 to 10%. If the content of Al ₂ O ₃ is too high, the meltability tends to decrease.

MgO, CaO, SrO, and BaO are components that lower the melting temperature, improve meltability, and lower the softening point. The total amount of these components is preferably 0 to 45%, 0.1 to 45%, particularly 1 to 40%. If the total amount of these components is too large, acid resistance tends to decrease. The content of each component of MgO, CaO, SrO and BaO is preferably 0 to 35%, 0.1 to 33%, particularly 1 to 30%, respectively. If the content of these components is too large, acid resistance tends to decrease.

ZnO is a component that lowers the melting temperature and improves meltability. The ZnO content is preferably 0 to 10%, 0.1 to 7%, particularly 1 to 5%. If the ZnO content is too high, acid resistance tends to decrease.

In addition to the above-mentioned components, various other components can be contained within the range that does not impair the effects of the present invention. For example, _{P2O5 , La2O3 , Ta2O5 , TeO2} , _TiO2 , _{Nb2O5 , Gd2O3} , _Y2O3 , _{CeO2 , Sb2O3 , SnO2 ,} Bi ₂ O ₃ , As ₂ O ₃ and ZrO ₂ may each be contained in an amount of 15% or less, further 10% or less, particularly 5% or less, and a total amount of 30% or less.

Note that since alkali metal components (Li ₂ O, Na ₂ O, K ₂ O, etc.) significantly reduce the acid resistance of the amorphous glass layer, it is preferable that they are substantially not contained.

The softening point of the glass constituting the amorphous glass layer is preferably 700 to 1000°C, particularly 750 to 900°C. If the softening point is too low, excessive flow occurs during firing, making it difficult to obtain a barrier layer with a uniform thickness. As a result, the function as a barrier layer may deteriorate. On the other hand, if the softening point is too high, it becomes difficult to obtain a dense barrier layer, and the function as a barrier layer may deteriorate.

The thickness of the barrier layer is preferably 30 μm or more, 50 μm or more, particularly 80 μm or more, so as to fully fulfill its function. Note that if the thickness of the barrier layer is too large, the dielectric constant and dielectric loss of the glass ceramic dielectric as a whole will increase, so it is preferably 300 μm or less, 200 μm or less, particularly 150 μm or less.

(Method for manufacturing glass ceramic dielectric)
FIG. 2 is a schematic cross-sectional view showing an embodiment of the method for manufacturing a glass ceramic dielectric of the present invention.

First, a green sheet 2' for the glass-ceramic layer containing crystalline glass powder and a green sheet 3' for the barrier layer (amorphous glass layer) containing amorphous glass powder were produced by a known green sheet method. and prepare. Specifically, a vehicle containing a resin binder, an organic solvent, etc. is added to raw material crystalline glass powder or amorphous glass powder, and a vehicle containing such as a resin binder or an organic solvent is added and kneaded to produce a glass paste. Each green sheet is obtained by forming a sheet onto a base material such as a (polyethylene terephthalate) film using a doctor blade. The thickness of the green sheet may be appropriately selected depending on the desired thickness of the glass ceramic layer 2 and barrier layer 3, but is usually about 100 to 250 μm, more preferably about 120 to 200 μm. If necessary, each green sheet may be mechanically processed to provide through holes for forming conductors and electrodes.

Next, the obtained glass-ceramic layer green sheet 2' and barrier layer green sheet 3' are laminated to obtain a laminate. Here, it is preferable to improve the adhesion of each layer by thermocompression bonding each green sheet using a hot press. In FIG. 2A, three green sheets 2' for glass ceramic layers are laminated, and one green sheet 3' for barrier layers is laminated on both sides of the three green sheets 2' for producing a laminate 1'. The number of green sheets 2' for the glass ceramic layer to be laminated may be appropriately selected depending on the desired thickness of the glass ceramic layer 2, but is usually 2 to 10 sheets, more preferably 3 to 7 sheets. The number of stacked green sheets 3' for barrier layer may be one, but two or more may be stacked.

Subsequently, the laminate 1' is fired while being sandwiched between a pair of restraining sheets 4 (FIG. 2(b)). Thereby, the glass ceramic layer green sheet 2' and the barrier layer green sheet 3' become the glass ceramic layer 2 and the barrier layer (amorphous glass layer) 3, respectively. In this way, a glass ceramic dielectric 1 is obtained in which barrier layers 3 are formed on both main surfaces of the glass ceramic layer 2 (FIG. 2(c)).

The restraining sheet 4 serves to suppress shrinkage of the laminate 1' in the planar direction during firing. As the restraint sheet 4, for example, a green sheet containing ceramic powder such as alumina powder can be used. Note that when the restraint sheet 4 is removed after firing, the ceramic powder contained in the restraint sheet 4 may adhere to the surface of the barrier layer 3; Since it has almost no effect, it is not necessarily necessary to remove it by polishing or the like.

The firing temperature is preferably a temperature at which the crystalline glass powder contained in the glass-ceramic layer green sheet 2' is sufficiently crystallized. Specifically, the firing temperature is higher than or equal to the crystallization temperature of the crystalline glass powder, further (crystallization start temperature of the crystalline glass powder + 50°C) or higher, particularly (crystallization start temperature of the crystalline glass powder + 100°C) or higher. It is preferable that (firing conditions A). In this way, it is possible to obtain a glass ceramic dielectric 1 that satisfies desired characteristics such as dielectric loss.

From another point of view, the firing temperature is preferably a temperature at which the amorphous glass powder contained in the barrier layer green sheet 3' is sufficiently softened and fluidized to be sintered. Specifically, the firing temperature is at least the softening point of the amorphous glass powder, further at least (the softening point of the amorphous glass powder + 50°C), especially at least (the softening point of the amorphous glass powder + 100°C). This is preferable (firing condition B). In this way, it is possible to obtain a glass ceramic dielectric 1 on which a barrier layer 3 having desired characteristics is formed.

The firing temperature preferably satisfies both the firing conditions A and B above. This makes it possible to obtain a glass ceramic dielectric 1 having desired characteristics. Note that the specific firing temperature is preferably 800 to 1000°C, 800 to 950°C, particularly 850 to 900°C.

Note that a circuit board is obtained by plating the surface of the barrier layer 3 in the obtained glass ceramic dielectric 1 to form metal wiring (not shown).

The present invention will be described below based on Examples, but the present invention is not limited to these Examples.

(Example 1)
(a) Preparation of green sheet for glass-ceramic layer Glass composition in mass %: SiO ₂ 43.4%, Al ₂ O ₃ 4%, BaO 28%, CaO 10%, MgO 14.5%, CuO 0.1 %, and after melting at 1550° C., molding and cooling were performed to produce crystalline glass. The obtained crystalline glass was pulverized to produce a crystalline glass powder (crystallization initiation temperature: 890° C.) with an average particle diameter D ₅₀ of 2 μm.

For a mixed powder containing 60 parts by mass of crystalline glass powder and 40 parts by mass of alumina powder with an average particle diameter of 2 μm, 15 parts by mass of polyvinyl butyral (PVB), 3 parts by mass of benzyl butyl phthalate, and toluene. After mixing and kneading 50 parts by mass, a green sheet for a glass ceramic layer having a thickness of 150 μm was obtained by a doctor blade method.

(b) Production of green sheet for barrier layer (amorphous glass layer) Glass composition in mass %: 50% SiO ₂ , 5% B ₂ O ₃ , 6% Al ₂ O ₃ , 2% ZnO, 12% CaO A raw material powder was prepared to have a BaO content of 25%, melted at 1200 to 1700°C, molded, and cooled to produce an amorphous glass. The obtained amorphous glass was pulverized to produce an amorphous glass powder (softening point: 850° C.) with an average particle diameter D ₅₀ of 2 μm.

After mixing and kneading 100 parts by mass of amorphous glass powder, 15 parts by mass of polyvinyl butyral (PVB), 3 parts by mass of benzyl butyl phthalate, and 50 parts by mass of toluene, a thickness of 150 μm was obtained by a doctor blade method. A green sheet for barrier layer was obtained.

(c) Production of glass ceramic dielectric Each of the green sheets obtained above was cut into 30 mm x 30 mm. A laminate was obtained by laminating three glass-ceramic layer green sheets, laminating barrier layer green sheets on both surfaces thereof, and thermally pressing and bonding them. The obtained laminate was baked at 900° C. for 20 minutes while being sandwiched between a pair of alumina green sheets serving as restraining sheets. As a result, a glass ceramic dielectric material was obtained in which a barrier layer (amorphous glass layer) (thickness: 100 μm) was formed on both main surfaces of a glass ceramic layer (thickness: 300 μm). In addition, when the precipitated crystals in the glass ceramic layer were identified using a powder X-ray diffraction apparatus (Rigaku Co., Ltd. RINT2100), it was confirmed that diopside and barium feldspar were precipitated.

(d) Evaluation of acid resistance The glass-ceramic dielectric obtained above was immersed in 10% by mass diluted hydrochloric acid prepared in an ultrasonic bath, held under ultrasonic vibration for 20 minutes at 25°C, and then purified. It was thoroughly washed with water and dried at 110°C for 30 minutes. When the mass change of the glass-ceramic dielectric material was measured before and after immersion, the mass decrease was 0.1% by mass or less. Furthermore, when the sample surface was observed using a scanning electron microscope, no deterioration was observed before and after immersion.

(Example 2)
(a) Production of green sheet for glass ceramic layer A green sheet for glass ceramic layer having a thickness of 150 μm was obtained in the same manner as in Example 1.

(b) Production of green sheet for barrier layer (amorphous glass layer) Glass composition in mass %: SiO ₂ 43%, B ₂ O ₃ 5%, Al ₂ O ₃ 6%, ZnO 7%, CaO 8% , SrO 8%, and BaO 23%, a raw material powder was prepared, melted at 1200 to 1700° C., then molded and cooled to produce an amorphous glass. The obtained amorphous glass was pulverized to produce an amorphous glass powder (softening point: 800° C.) with an average particle diameter D ₅₀ of 1.5 μm.

After mixing and kneading 100 parts by mass of amorphous glass powder, 15 parts by mass of polyvinyl butyral (PVB), 3 parts by mass of benzyl butyl phthalate, and 50 parts by mass of toluene, a thickness of 150 μm was obtained by a doctor blade method. A green sheet for an amorphous glass layer was obtained.

(c) Preparation of glass ceramic dielectric material Using each of the green sheets obtained above, a barrier layer (an amorphous glass layer ) (thickness: 100 μm) was obtained. In addition, when the precipitated crystals in the glass ceramic layer were identified using a powder X-ray diffraction apparatus (Rigaku Co., Ltd. RINT2100), it was confirmed that diopside and barium feldspar were precipitated.

(d) Evaluation of Acid Resistance The glass ceramic dielectric obtained above was evaluated for acid resistance in the same manner as in Example 1, and the mass loss was 0.1% by mass or less. Moreover, no deterioration was observed on the sample surface before and after immersion.

(Comparative example)
A laminate was obtained by laminating three green sheets for glass ceramic layers obtained above and hot pressing to bond them under heat. The obtained laminate was baked at 900° C. for 20 minutes while being sandwiched between a pair of alumina green sheets serving as restraining sheets. As a result, a glass ceramic dielectric consisting of only a glass ceramic layer (thickness: 300 μm) was obtained.

When acid resistance was evaluated in the same manner as in Example 1, the mass reduction was 4% by mass. Furthermore, after the acid resistance evaluation, many voids due to elution of glass components were observed on the sample surface.

From the acid resistance evaluation results of Examples and Comparative Examples, the glass ceramic dielectric of the present invention has excellent acid resistance due to the barrier layer (amorphous glass layer) formed on the surface of the glass ceramic layer. I understand. Therefore, when metal wiring is formed by plating, deterioration of the glass-ceramic layer is suppressed, and as a result, it is thought that properties such as dielectric loss are less likely to deteriorate.

The glass ceramic dielectric of the present invention is suitable for circuit boards for microwaves and the like.

1 Glass ceramic dielectric 1' Laminate 2 Glass ceramic layer 2' Green sheet for glass ceramic layer 3 Barrier layer 3' Green sheet for barrier layer 4 Restraint sheet

Claims (9)

comprising a glass ceramic layer and a barrier layer formed on the main surface thereof,
The glass ceramic layer contains, as a glass composition, 20 to 65% of SiO ₂ , 3 to 25% of CaO, 7 to 30% of MgO, 0.5 to 20% of Al ₂ O ₃ , and 5 to 40% of BaO. Consists of a sintered body of powder containing crystalline glass powder,
the glass ceramic layer contains diopside crystals and feldspar crystals,
The thickness of the barrier layer is 30 to 300 μm ,
The barrier layer has the following glass composition by mass%: SiO ₂ 40-85%, B ₂ O ₃ 1-15%, Al ₂ O ₃ 0-25%, ZnO 0-10%, BaO 1-35%, MgO+CaO+SrO+BaO 1 A glass-ceramic dielectric characterized in that it is made of amorphous glass containing ~45% . The glass-ceramic dielectric material according to claim 1, characterized in that barrier layers are formed on both main surfaces of the glass-ceramic layer. The glass-ceramic dielectric material according to claim 1 or 2 , characterized in that the amorphous glass contains substantially no alkali metal component. The glass-ceramic dielectric material according to any one of claims 1 to 3, wherein the crystalline glass powder satisfies the relationship 1≦SiO ₂ /BaO≦4 in terms of mass ratio. The glass-ceramic dielectric according to any one of claims 1 to 4 , wherein the glass-ceramic layer is made of a sintered body of powder containing 30 to 100% by mass of crystalline glass powder and 0 to 70% by mass of filler powder. body. The glass-ceramic dielectric material according to claim 5 , wherein the filler powder contains an Al component. The glass ceramic dielectric material according to any one of claims 1 to 6 , characterized in that it is used for a circuit board. A circuit board characterized in that metal wiring is formed on the surface of the barrier layer in the glass ceramic dielectric according to claim 7 . A method for manufacturing a glass-ceramic dielectric according to any one of claims 1 to 7 , comprising:
preparing a glass-ceramic layer green sheet containing crystalline glass powder and a barrier layer green sheet containing amorphous glass powder;
A step of laminating a green sheet for a glass ceramic layer and a green sheet for a barrier layer to obtain a laminate, and
a step of firing the laminate;
A method for producing a glass-ceramic dielectric, comprising: