JP2001313470A - Capacitor including wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor including wiring board which uses low temperature baked porcelain composition which can be made dense at a low temperature equal to or lower than 1000 deg.C and has both stable low permittivity and low dielectric loss, as an insulating layer. SOLUTION: The low temperature baked porcelain composition containing Sr2MgSi2O7 crystal as main crystal is used for the insulating layer. For a dielectrics layer, a dielectrics layer whose main component is barium titanate having high permittivity and to which a small quantity (<=20 mass %, preferably <=10 mass %) of sintering auxiliary is added is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a built-in capacitor which can be fired at a low temperature of 1000.degree. C. or less, has excellent dielectric properties in a high frequency range, and uses a high-strength low-temperature fired porcelain composition for an insulator layer. Related to a wiring board. It is suitable as a wiring board with a built-in capacitor using a low-resistance metal such as Ag or Cu for the wiring layer.

[0002]

2. Description of the Related Art In order to cope with recent increases in signal processing speed and wiring density, it is necessary to incorporate passive circuit elements such as capacitors inside a wiring board. In addition, in order to reduce the transmission loss of electric signals as a wiring board, it is required that the wiring can be simultaneously fired at a firing temperature of 1000 ° C. or lower with a wiring made of a low-resistance metal such as Ag or Cu having a lower resistance. You. Further, the insulating layer itself needs to have a lower dielectric constant in order to suppress dielectric loss. In order to meet such market demands, various studies have been made on low-temperature fired wiring boards using a low dielectric loss glass-ceramic composition containing a specific crystal phase for an insulator layer.

A wiring board with a built-in capacitor in which an insulator layer contains a crystal phase such as forsterite, monticelite, akermanite, enstatite, etc. is disclosed in Japanese Patent Application Laid-Open No. Hei 2-305490.
JP, JP-A-3-241724, JP-A-4-1
No. 67412 and JP-A-5-55079.

[0004] Various studies have been made on glass-ceramic compositions for use as an insulator layer in which a specific crystal phase is precipitated by firing at a low temperature of 1000 ° C or lower. JP-A-7-11313 discloses a composition for a low-temperature fired substrate containing crystals such as anorthite and garnite.
No. 72 is disclosed. A low dielectric loss glass composition containing a crystal such as forsterite or cordierite is disclosed in Japanese Patent Publication No. 11-511719. Further, glass ceramic compositions containing diopsite in the main crystal are disclosed in JP-A-10-120436 and JP-A-11-4104.
No. 9531. In addition, so far Sr
_{The use of 2} MgSi ₂ O ₇ crystal as a low-temperature fired porcelain composition and a wiring board with a built-in capacitor is not known.

[0005]

As described above, there is known a wiring board with a built-in capacitor in which a specific crystal is deposited on an insulator layer to solve an increase in dielectric loss at a high frequency of the wiring board. However, in order to precipitate crystals efficiently, 1
It is necessary to fire at a temperature of 200 ° C. or higher. for that reason,
Simultaneous firing was not possible using Ag or Cu, which are low resistance metals having a melting point of 1100 ° C. or less. Ag instead
Since a high melting point and high resistance metal such as / Pd is used, transmission loss of an electric signal due to wiring resistance could not be reduced.

In order to solve the above-mentioned problems, as described above, low-temperature fired porcelain compositions having stable low dielectric constant and low dielectric loss by depositing specific crystals by firing at a low temperature of 1000 ° C. or less have been studied. Have been. However, since crystallized glass is used as a starting material, there is a problem that the degree of crystallization is likely to vary due to the influence of the pulverized state of the glass material, impurities, and the like, and it is difficult to obtain a stable specific wiring substrate.

[0007]

According to a first aspect of the present invention, there is provided a wiring board with a built-in capacitor, wherein the insulator layer comprises a low-temperature fired ceramic composition containing Sr ₂ MgSi ₂ O ₇ crystal as a main crystal for the insulator layer. Is the gist. Sr ₂ MgSi ₂ O for the insulator layer
By containing _seven crystals as the main crystal, it is possible to exhibit excellent dielectric properties in a high frequency region, suppress excessive glass component diffusion into the capacitor part, and form a capacitor part with stable performance.

[0008] The insulator layer of the low-temperature fired wiring board of the present invention comprises:
Usually, it has a crystal phase of 60 to 99.7% by weight. The above “Sr ₂ MgSi ₂ O ₇ crystal” is contained as a “main crystal phase” and accounts for at least 20% by weight of all crystal phases.
It is preferably contained in an amount of 0 to 100% by weight.
More preferably, it is contained in an amount of 0 to 70% by weight. This S
The r ₂ MgSi ₂ O ₇ crystal has excellent dielectric properties in a high frequency range, has a large coefficient of thermal expansion, and has a high melting point of 1560 ° C., so that it can stably exist when fired at 1000 ° C. or lower.

In particular, Sr with respect to 100% by mass of the insulator layer
₂ MgSi ₂ O ₇ crystal 30 to 99.7% by weight (preferably 40 to 80 wt%, more preferably 50 to 70 wt%) dielectric properties may be enhanced to contain. Further, the ceramic component is 0.1 to 10% by weight (preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight) in terms of oxide, and the boron component is 0.1 to 10% in terms of oxide. 10% by weight
(Preferably 0.1 to 5% by weight, more preferably 0.1 to 5% by weight.
-3% by weight), and 0.1% of alkali metal component in terms of oxide.
To 10% by weight (preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight). Sinterability and mechanical strength can be improved. In addition, other components may be contained in an amount of 40% by weight or less.

Here, a glass powder is not used as a starting material, but a calcined powder containing Sr ₂ MgSi ₂ O ₇ crystal as a main crystal is used. By adding a small amount of a sintering aid to the calcined powder, the above-mentioned problems that occur when glass powder is used can be solved. It is preferable to use B ₂ O ₃ or an alkali metal oxide (particularly Li ₂ O) as the sintering aid.
This is because sinterability can be improved without inhibiting the precipitation of the main crystal phase. The term “calcined product” refers to a raw material powder containing a predetermined component at 1000 to 1200 ° C. (preferably 1000 to
Baking at 1150 ° C., more preferably 1000 to 1100 ° C., and cooling to room temperature without quenching (decreasing the temperature by 20 ° C. or more per minute). 80% by weight or more (more preferably 90% by weight or more, particularly 95 to 100% by weight) of the calcined product is preferably crystalline in view of dielectric properties.

The dielectric layer can be fired at 1000 ° C. or less.
Anything should do. For example, BaTiO_Three,, BaTi_Four
O₉, SrTiO_Three, BaZrO_Three, CaZrO_Three, SrZ
rO _Three, BaSnO_Three, CaSnO_Three, SrSnO_ThreeMainly
And a small amount of sintering aid (20% by mass)
Below, preferably 10% by mass or less)
Is good. Rare earth elements such as Nd and Nb
It preferably contains an element or the like. B as a sintering aid_TwoO_ThreeAnd
Alkali metal oxide (particularly Li_TwoO), ZnO, Si
O_Two, CuO, Bi_TwoO_Three, MgO, MnO, etc.
Is good. By minimizing the addition of sintering aids, insulation
Sr by suppressing the diffusion of the glass component into the layer _TwoMgSi_TwoO₇
The precipitation of the crystal phase is not hindered.

This dielectric layer has a temperature of 1000 ° C. or less (850
(Up to 1000 ° C.), it is possible to fire simultaneously with the insulator layer and the wiring layer made of Ag or Cu. The dielectric layer of the wiring board with a built-in capacitor of the present invention has a capacitance of 500 pF or more (preferably 600 pF, more preferably 700 pF) and a dielectric constant ε of 1000 or more (preferably 1200 or more, more preferably 1500 or more, more preferably 2000 or more). Above).

The dielectric of the wiring board with a built-in capacitor of the present invention
The layer is based on barium titanate with a high dielectric constant
While adding a small amount of a sintering aid (20% by mass or less,
(Preferably 10% by mass or less).
Good. B as a sintering aid_TwoO_ThreeAnd alkali metal oxides (special
Li_TwoO), ZnO, SiO_Two, CuO, Bi_TwoO_Three,
It is preferable to use MgO, MnO, or the like. This dielectric layer
Can be fired at low temperatures below 1000 ° C (850-1000 ° C)
The insulating layer and the wiring layer made of Ag or Au
Can be fired at the same time as
Product stability using available commercially available barium titanate
Can be achieved. In addition, BaTi _FourO₉The main component or
Alternatively, those containing as accessory components may be used. For additives
As for the above, those described above can be used.

Each of these raw materials is formed into a green sheet using a known doctor blade method. The additional components are
The powder of each component may be used as a mixture, or a glass powder containing each component may be used. Further, an organic acid salt or the like which becomes each component by firing may be used. In this case, a powdery substance or a liquid substance such as a naphthenate may be used. A wiring layer is formed on the green sheet by screen printing using a conductive paste containing a low-resistance metal such as Ag or Au. The green sheet is pressed into a predetermined configuration and fired to form a laminate that becomes a wiring board with a built-in capacitor. This laminate is kept at 1000 ° C. or less (850 to 10
(00 ° C.) to obtain a desired wiring board with a built-in capacitor.

The insulating layer of the wiring board with a built-in capacitor according to the present invention has Sr ₂ MgSi ₂ O having a long diameter of 20 μm or less.
_It is good that ₇ crystal particles are dispersed. Preferred major axis is 1
The major axis is preferably 5 μm or less, more preferably 5 μm or less, and still more preferably 5 μm or less. The lower limit is 0.1 μm or more. The content of the crystal having the predetermined particle size is
30 to 99.7% by weight, preferably 30 to 7% by weight.
More preferably, it is 0% by weight. When the particle size and the content are in the above ranges, a low-temperature fired porcelain composition having a low dielectric constant, a small dielectric loss, and a high thermal expansion is obtained.

For measuring the major axis, it is preferable to observe the structure of the lap section (so-called mirror-polished surface) of the sintered body. For example, it is convenient and easy to confirm using a photograph of a SEM image of 2000 times magnification. The major axis is one Sr ₂ MgSi ₂ O ₇
It is preferable to connect the two farthest points of the crystal grains with a straight line and take the length. Ten Sr ₂ MgSi ₂ O ₇ crystal particles are arbitrarily extracted from each photograph of the SEM image, and the average value is taken. For one sample, the same operation is performed for at least three or more locations, and the total average value is taken as the major axis of the Sr ₂ MgSi ₂ O ₇ crystal particles.

The melting point of the Sr ₂ MgSi ₂ O ₇ crystal is 1560.
Because of the high temperature of 1000 ° C., it is stable at the firing temperature (1000 ° C. or lower) of the wiring board with a built-in capacitor of the present invention having an insulator layer using a calcined powder containing Sr ₂ MgSi ₂ O ₇ crystal as a main crystal. Therefore, the dielectric characteristics can be effectively stabilized. In addition, since the content of the glass component in the insulator layer is small, the capacitor characteristics do not deteriorate due to the diffusion of the glass component into the dielectric layer during firing.

The insulator layer of the wiring board with a built-in capacitor of the present invention has a dielectric constant ε of 7 or less, preferably 6.5 or less.
In particular, it is preferable to adjust the pH to 6.0 or less (usually 4 or more). This is because the dielectric loss can be kept low. Preferably, the Q × f value (product of the no-load quality factor and the resonance frequency) is 3000 GHz or more, preferably 50 GHz or more.
It is preferable to prepare so as to be 00 GHz or more (usually, 20,000 GHz or less). Specifically, it can be realized by appropriately optimizing the firing conditions and powder state according to the composition ratio. Usually, when glass powder is used as a starting material, its dielectric constant ε exceeds 7. In the present invention, by using a calcined powder containing Sr ₂ MgSi ₂ O ₇ crystal as a main crystal as a starting material, the dielectric constant ε is reduced to 7 or less, and an excellent Q × f value of 3000 GHz or more is obtained. realizable. The dielectric constant, unloaded quality factor and resonance frequency are J
It can be measured according to IS R 1627,
f can be calculated from the no-load quality factor and the resonance frequency.

The insulator layer and the dielectric layer of the wiring board with a built-in capacitor of the present invention are preferably prepared so that the water absorption is 0.1% by mass or less. This is because, even when a low-resistance metal material such as Ag or Au is used for the wiring, the occurrence of problems such as ion migration can be effectively suppressed. The “water absorption” can be 0.1% or less, and can be 0.05% or less. This water absorption can be measured according to JISC 2141. The “thermal expansion coefficient” can be 8 to 15 ppm / ° C., and can be 10 to 15 ppm / ° C. This coefficient of thermal expansion can be measured by a differential expansion type thermomechanical analyzer or the like.

The flexural strength of the insulator layer is 150 MPa.
It is better to prepare it as described above. In order to ensure the adhesion strength of the wiring and the strength of the substrate itself in mounting and the like, the pressure is preferably 180 MPa or more. By appropriately optimizing the sintering conditions and the state of the powder in accordance with the composition ratio and also adjusting the water absorption and the bending strength, it is possible to effectively increase the reliability of the wiring board. This flexural strength is measured according to JIS R
1601 can be measured.

The insulator layer of the low-temperature fired wiring board according to the present invention comprises:
A crystal other than the Sr ₂ MgSi ₂ O ₇ crystal may be included as a sub crystal. As the sub-crystal, a SiO ₂ crystal (particularly α
-Quartz, cristobalite). Further, Li ₂ Si ₂
It is preferable that O ₅ crystals be contained.

According to a second aspect of the present invention, the insulating layer is made of SiO ₂
The gist is a wiring board with a built-in capacitor containing a system crystal (particularly, α-quartz, cristobalite) as a sub crystal. By simultaneously containing the SiO ₂ -based crystal, stabilization of the dielectric characteristics of the wiring board and lowering of the dielectric constant can be effectively promoted. In addition, since the Si component in the insulator layer is precipitated as SiO ₂ -based crystals, the amount of diffusion of the Si component into the capacitor portion can be minimized to stabilize the capacitor characteristics. As a method for obtaining such a wiring board with a built-in capacitor, it is effective to make the composition ratio of the calcined powder added to the green sheet forming the insulator layer by firing a composition rich in SiO ₂ .

The content of the SiO ₂ -based crystal is preferably 69.7% by mass or less, more preferably 20 to 60% by mass, based on 100% by mass of the insulator layer. By containing this quartz crystal, the relative dielectric constant can be further reduced, and the coefficient of thermal expansion can be increased (closer to the coefficient of thermal expansion of a printed wiring board or the like).

According to a third aspect of the present invention, the weight ratio of the SiO ₂ -based crystal to the Sr ₂ MgSi ₂ O ₇ crystal contained in the insulator layer is 2.33 or less (more preferably 0.4 to 0.43).
The gist is the wiring board with a built-in capacitor of 1.4).
By optimizing the weight ratio of the SiO ₂ -based crystal, the Si component in the insulator layer is effectively precipitated as the SiO ₂ -based crystal. It can be more effectively stabilized.

According to a fourth aspect of the present invention, there is provided a wiring board with a built-in capacitor in which an insulator layer contains a ceramic component, a boron component, and an alkali metal component as subcomponents.
As the ceramic component, alumina, zirconia, spinel, garnite, anorthite, and forsterite are preferable. It is possible to improve the strength of the wiring board and stabilize the dielectric characteristics. In particular, alumina is preferably used. The boron component contributes to lowering the firing temperature and increasing the density. Any material that can be converted into an oxide during the firing process may be used.
Particularly, B ₂ O ₃ is preferable. Decomposes below 1000 ° C and B ₂ O ₃
B or a metal boride that emits hydrogen can be used.

The alkali metal component has the effect of promoting the densification of the sintered body. In particular, the Li component is effective. This is effective when the composition ratio of the calcined powder is SiO ₂ rich. Any material may be used as long as it becomes an oxide during the firing process, and particularly, Li ₂ O is preferable. Alternatively, lithium organic acid can be used. The alkali metal component may be contained as a crystal phase, but may be contained as a glass phase at a grain boundary or the like.

Other than Li, it is preferable to use a Na component and a K component. Any material that can be converted into an oxide during the firing process may be used.
Particularly, Na ₂ O and K ₂ O are preferable. Alternatively, an organic acid salt can be used. In particular, it is most effective to use it together with the Li component. Since the sintered body can be densified with a smaller amount of addition, migration of metal ions such as Ag and Cu as wiring materials can be further reduced, and dielectric loss can be reduced.

According to a fifth aspect of the present invention, the main crystal, S, contained in 100% by mass of the low-temperature fired porcelain composition constituting the insulator layer is provided.
r ₂ MgSi ₂ O ₇ crystal, SiO ₂ -based crystal (α-
The gist is a wiring board with a built-in capacitor in which the contents (% by mass) of the quartz component, the cristobalite component, the ceramic component, the boron component, and the alkali metal component are specified. By optimizing the composition ratio, it is possible to obtain a wiring board with a built-in capacitor in which the dielectric constant is reduced and the dielectric characteristics are improved, and the capacitor characteristics are more effectively stabilized.

Sr ₂ MgSi ₂ O ₇ Crystal Content (V)
Is preferably 30 to 99.7% by mass (preferably 40 to 80% by mass, more preferably 50 to 70% by mass). It is possible to obtain a wiring board with a built-in capacitor excellent in dielectric characteristics, capacitor characteristics, strength, and simultaneous sinterability. Sr ₂ MgSi ₂
When the content of the O ₇ crystal is less than 30% by mass, the dielectric properties decrease. Also, if it exceeds 99.7% by mass, 1
Since firing at 000 ° C. or lower becomes difficult, simultaneous firing with low-resistance wiring such as Ag or Cu as a wiring material becomes difficult.

The content (W) of the subcrystal is preferably 69.7% by mass or less (preferably 20 to 60% by mass, more preferably 30 to 50% by mass). The content of the subcrystal is 0.1
If it is less than mass%, the dielectric constant tends to be as high as around 7. On the other hand, if the content exceeds 69.7% by mass,
Since it becomes difficult to bake below, Ag, C
Simultaneous firing with low resistance wiring such as u becomes difficult.

The content (X) of the ceramic component in terms of oxide is preferably 0.1 to 10% by mass. Stabilization of the dielectric properties of the wiring board can be promoted. As the ceramic component, alumina, zirconia, spinel, garnite, anorthite, and forsterite are preferable. In particular, alumina is preferred. When the content is less than 0.1% by mass, the stabilization of the dielectric properties cannot be effectively promoted. On the other hand, if the content exceeds 10% by mass, another crystal phase tends to precipitate, and the dielectric loss increases. A more preferred range is from 0.1 to 5% by mass. More preferably 0.1
３3% by mass.

The content (Y) of the boron component in terms of oxide is preferably 0.1 to 10% by mass. The firing temperature can be lowered and densification can be effectively achieved. Especially B ₂ O ₃
Is good. If this content is less than 0.1% by mass, the densification of the insulator layer cannot be effectively promoted. On the other hand, if the content exceeds 10% by mass, the dielectric properties (particularly, dielectric loss) increase and the capacitor properties deteriorate. A more preferred range is from 0.1 to 4% by mass. More preferably, the content is 0.1 to 3% by mass.

The content of alkali metal components in terms of oxides
The content (Z) is preferably 0.1 to 10% by mass. Firing temperature
Low temperature and densification can be effectively achieved. in particular,
Li _TwoO should be required. This content is 0.1 quality
If the amount is less than the amount%, the densification of the insulator layer can be effectively promoted.
I can't. If the content exceeds 10% by mass,
Ion migration occurs when manufacturing wire substrates
And the capacitor characteristics are degraded. Yo
A more preferable range is 0.1 to 5% by mass. More preferred
Or 0.1 to 3% by mass.

According to a sixth aspect of the present invention, the insulator layer is made of Sr ₂ MgSi ₂ O ₇ crystal particles having a major axis of 0.1 to ₂₀ μm.
The gist is a wiring board with a built-in capacitor containing 0% by mass or more. The major axis is preferably from 0.1 to 10 μm, and more preferably from 0.1 to 5 μm. Also,
The content of the crystal having the predetermined major axis is from 30 to 99.
It is preferably 7% by weight, more preferably 30 to 70% by weight. When the major axis and the content are in the above ranges, an insulator layer having a low dielectric constant, a small dielectric loss, and a high thermal expansion can be obtained, and ion migration of a wiring material when formed into a wiring board is more effectively suppressed. be able to. Further, a wiring board with a built-in capacitor having more stabilized capacitor characteristics can be obtained.

According to a seventh aspect of the present invention, the insulating layer is made of Sr ₂ M
A calcined powder 70 or more containing at least one of gSi ₂ O ₇ crystal, SrSiO ₃ crystal and MgSiO ₃ crystal as a main component
99.7% by weight, 0.1 to 10% by weight of the ceramic component (in terms of oxide), 0.1 to 10% by weight of the boron component (in terms of oxide), and 0.1 to 0.1% of the alkali metal component.
The gist is a wiring board with a built-in capacitor made of a low-temperature fired porcelain composition obtained by firing a molded body obtained by mixing and molding 10% by mass (in terms of oxide) at 850 to 1000 ° C.
By specifying the amount of the calcined powder in the insulator layer and the amount of each additive in terms of oxide, the dielectric constant of the insulator layer is reduced and the capacitor characteristics of the dielectric layer are further improved.
Ion migration of wiring materials such as g and Cu can be more effectively suppressed.

These raw materials can be formed into a sheet by a known doctor blade method to form a pressure-bonded laminate, or can be made into a paste to form a multilayer using a thick film printing technique. This calcined product has an average particle size of 0.1 to 20 μm (more preferably 0.1 to 10 μm, and still more preferably 0.1 to 5 μm).
Is preferred. This average particle size is 0.1μ
If it is less than m, handling becomes inconvenient, such as easy scattering in the manufacturing process, and if it exceeds 20 μm, the formation, especially the moldability in the doctor blade method or the like is liable to deteriorate, which is not preferable.

After demolding this molded product, 85
Baking is performed in the range of 0 to 1000 ° C. When Ag is used for the wiring, firing is performed in an air atmosphere, and when Cu is used, firing is performed in a reducing atmosphere. Au, Pt, and Pd are used or used in combination as necessary.

Unlike the conventional case using crystallized glass, an insulating layer is formed by a method of sintering a calcined powder containing Sr ₂ MgSi ₂ O ₇ crystal as a main crystal with a sintering aid. In addition, variation in crystallization due to the diffusion metal can be suppressed. As a result, there is no difference in the degree of sintering between the metallized surface and the other portions, and there is an advantage that there is no problem of substrate warpage. In addition, since the content of the glass component in the insulator layer is small, the capacitor characteristics do not deteriorate due to the diffusion of the glass component into the dielectric layer during firing.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wiring board with a built-in capacitor of the present invention will be described.
A description will be given using the substrate for characteristic evaluation (Example 1) and the example (Example 2) shown in FIG. FIG. 1 is a sectional view showing an embodiment of a wiring board (1) with a built-in capacitor according to the present invention.
2 is an insulator layer, 3 is a capacitor part, 4 is a wiring layer, 5 is a via hole conductor, 6 is a dielectric layer, and 7 is a capacitor electrode.

(Example 1) (1) Preparation of calcined products A to E First, characteristics of the insulator layer of the present invention are evaluated. Table 1
The silica powder, the magnesia powder, and the strontium oxide powder are mixed in the ratio shown in the following. This powder is calcined at the calcining temperature shown in Table 1 for 2 hours.

The obtained calcined product is in the form of powder, and CuKα
X-ray diffraction measurement using X-rays revealed that calcined products A, B and D
Was found to contain Sr ₂ MgSi ₂ O ₇ crystal, SrSiO ₃ crystal and α-quartz crystal. Further, the calcined products C and E are made of Sr ₂ MgSi ₂ O ₇ crystal, MgSiO ₃ crystal, Mg
It was found to contain ₃ SiO ₄ crystal and α-quartz crystal.

[0042]

[Table 1]

(2) Preparation and Evaluation of Insulator The calcined products A to E prepared in (1) were mixed with alumina powder (Al ₂ O ₃ ), boron oxide powder (B ₂ O ₃ )
Mixing lithium oxide powder (Li ₂ O), sodium oxide powder (Na ₂ O) and potassium oxide powder (K ₂ O),
Further, after adding a binder and ethanol, the mixture is granulated, and
Pressing and molding with MPa. Thereafter, isotropic isostatic pressing (CIP) treatment is performed at 150 MPa, and then firing is performed at a firing temperature shown in Table 2 in an air atmosphere.

[0044]

[Table 2]

Water absorption, coefficient of thermal expansion, bending strength, relative permittivity
And the five characteristics of the product of the no-load quality factor and the resonance frequency.
Measure as below. Table 3 shows the results. -Water absorption: Measured according to JIS C 2141. Coefficient of thermal expansion: The sintered body obtained in (2) has a diameter of 4 mm,
Processed to a length of 20 mm, differential expansion at 30-400 ° C
Thermo-mechanical analyzer (Model “TM” manufactured by Rigaku Corporation)
A8140C "). -Bending strength: The sintered body obtained in (2) is 40 mm in length,
Grind to a thickness of 3mm and a width of 4mm, JIS R 1601
It is measured by a three-point bending strength according to. -Dielectric properties: Parallel conductor plate according to JIS R 1627
-Type dielectric resonator method TE ₀₁₁Resonance frequency 8 depending on the mode
Measure at ~ 9 GHz.

[0046]

[Table 3]

When the sintered bodies of Experimental Examples 1 to 12 obtained in (2) were subjected to X-ray diffraction measurement using CuKα ray, Sr ₂ MgSi ₂ O ₇ crystal was observed as a main crystal phase in each case. . Among them, the X-ray diffraction chart of Experimental Example 8 is shown in FIG. In each case, the sintering temperature was 1000 ° C. or less and the water absorption was reduced to 0.1% or less, and it was found that these were low-temperature sintering porcelain compositions which were sufficiently sintered at a low temperature.

In the X-ray diffraction measurement, Experimental Examples 3, 6 and 1
From each experimental example except for 0, in addition to the Sr ₂ MgSi ₂ O ₇ crystal,
Quartz crystals and Li ₂ Si ₂ O ₅ crystals were detected. on the other hand,
In Experimental Examples 3, 6, and 10, quartz crystals were detected in addition to Sr ₂ MgSi ₂ O ₇ crystals.

Further, the surface of each sintered body was mirror-polished, and the surface was observed with a scanning electron microscope.
Sr ₂ MgSi ₂ O ₇ crystal grains Experimental example 5 .mu.m 1 to 1
2 were observed.

Further, according to Tables 1 to 3, in Experimental Examples 1 to 10 having characteristics suitable for a wiring board, the relative dielectric constant is 5.6 to 6.4, indicating that the dielectric constant is low.
Particularly, in Experimental Examples 7 to 10, it is excellent at 5.6 to 5.9. Further, Qu × f is as large as 3900 to 5500 GHz, and in particular, in Experimental Examples 5, 6, 8 and 9, 5100 to 5500 GHz.
It is excellent at 5500 GHz. Furthermore, the bending strength is 150
１９０190 MPa, and particularly, Experimental Examples 2, 4, 5, and 7
At 10 to 10, it is excellent at 170 to 190 MPa. Also,
The coefficient of thermal expansion is as large as 10.2 to 11.4 ppm / ° C. (close to the coefficient of thermal expansion of a printed wiring board or the like), and particularly excellent in Experimental Examples 4 to 5 as 12.1 to 12.4 ppm / ° C.

In Experimental Examples 11 and 12, both the transverse rupture strength and the coefficient of thermal expansion are sufficiently practical. However, in the measurement method (3), resonance is weak and measurement cannot be performed.
The relative permittivity can be measured by the RF impedance method. The values are almost the same as those in Experimental Examples 1 to 10, and it is considered that these materials are preferably used at a relatively low frequency of 1 GHz or less. This is because, in Experimental Example 11, the contents of Li, Na and K exceeded 10% by weight, and in Experimental Example 12, the B content exceeded 10% by weight. Conceivable.

(3) Fabrication and Evaluation of Dielectric Next, the characteristics of the dielectric layer of the present invention are evaluated. Commercially available BaTiO ₃ powder, B ₂ O ₃ powder, and Li ₂ CO ₃ powder are mixed to have the composition shown in Table 4. A resin binder and ethanol are added to the mixed powder and mixed using a pot mill to obtain a slurry. The slurry is spray-dried to obtain a granulated powder.

The granulated powder was subjected to 80MP using a press machine.
Form into a plate at the pressure of a. This molded plate is 150 MPa
A molded product is obtained by a CIP method (cold isostatic pressing method) at a pressure of. This molded body was fired under the firing conditions (900 to
(950 ° C.) to obtain a target sintered body.

This sintered body is evaluated as follows. First, the sintered body is made into a 58 mm square plate-shaped sample. A disc-shaped electrode having a diameter of 38 mm and a ring-shaped guard electrode having a diameter of 40 mm are formed on the surface of the electrode, and the electrode is also formed on the entire back surface. Impedance analyzer (HP4194A manufactured by Hewlett-Packard) and test jig (HP16451 manufactured by Hewlett-Packard)
Is used to measure the capacitance at a frequency of 1 MHz and a reference temperature of 25 ° C. The dielectric constant ε is calculated from the obtained capacitance and the sample size. Table 5 shows the results.

[0055]

[Table 4]

[0056]

[Table 5]

Each sample had a capacitance of 600 pF or more (755 pF for sample No. 14, and 620 pF for sample No. 15).
pF) and a dielectric constant ε of 1000 or more (20 for sample No. 14).
30 and sample number 15 and 1360), which is a good result.
Although the composition is different, the higher the firing temperature, the better the characteristics.

(4) Investigation of the Influence of the Insulator on the Dielectric Next, it is evaluated whether or not the dielectric layer has any effect on the capacitor characteristics when the dielectric layer is fired in a state where the dielectric layer is sandwiched between the dielectric layers. . Combinations of the insulator layer and the dielectric layer are as shown in Table 6. An acrylic binder, a plasticizer, a dispersant, toluene, and methyl ethyl ketone are added to a mixed powder having a composition ratio corresponding to a combination of Sample Nos. 16 to 20 in Table 6 to prepare a slurry. This slurry is formed into a green sheet having a thickness of 300 μm using a known doctor blade method.

The green sheets of the dielectric layer are laminated so as to have a thickness of 3.4 to 4 mm after firing to form a laminate. A green sheet of an insulator layer having a thickness of 3.4 to 4 mm after firing is also laminated on both surfaces of the laminate. A binder removal treatment is performed at 250 ° C. in an air atmosphere. Then 900-950 ° C under nitrogen atmosphere
(Hold for 2 hours). Thereafter, the insulator layer is polished and removed while leaving the dielectric layer, to obtain a target substrate for property evaluation.

The substrate for characteristic evaluation is evaluated as follows. First, the sintered body is made into a 58 mm square plate-shaped sample. Φ38mm disk-shaped electrode on its surface and φ40m around it
An m-shaped guard electrode is formed, and an electrode is also formed on the entire back surface. Impedance analyzer (HP4194A, Hewlett-Packard) and test jig (HP164, Hewlett-Packard)
51), the capacitance is measured at a frequency of 1 MHz and a reference temperature of 25 ° C. The dielectric constant ε is calculated from the obtained capacitance and the sample size. Table 6 shows the results.

[0061]

[Table 6]

From the results shown in Table 6, it can be seen that even when the insulating layer is sandwiched and fired, the capacitor characteristics of the dielectric layer are hardly affected. Although there is a difference in composition,
The higher the firing temperature, the better the characteristics, as in the case where the dielectric layer was used alone.

Example 2 A slurry was prepared by adding an acrylic binder, a plasticizer, a dispersant, toluene, and methyl ethyl ketone to a mixed powder having a composition ratio of a combination of Sample Nos. 21 to 26 in Table 7. This slurry is formed into a green sheet using a known doctor blade method. The thickness of the insulator layer is 120 μm and the thickness of the dielectric layer is 60 μm
And

As a comparative example (sample No. 26), a calcined powder (33.93% by weight of strontium oxide powder and magnesia powder) which precipitates Sr ₂ MgSi ₂ O ₇ crystals at the stage of finally forming a sintered body was used. 7.22% by weight, silica powder 53.73% by weight, alumina powder 0.85% by weight,
A mixture of 2.56% by weight of boron oxide powder and 1.71% by weight of lithium oxide powder was mixed at 850 ° C, 900 ° C and 9%.
(Calcination at 50 ° C.). Then, similarly, a green sheet having a thickness of 120 μm is formed by using a known doctor blade method.

A via hole having a diameter of 250 μm is formed at a predetermined position of these green sheets using a mold. An Ag paste is filled in the via hole and printed to form a via hole conductor. Thereafter, an Ag paste is printed in a predetermined pattern on the green sheet using a known screen printing method to form a wiring layer and a capacitor electrode. The printing thickness is 20 μm. The printed green sheets are pressure-bonded and laminated according to the combinations shown in Table 7 so as to have the configuration shown in FIG. 1 to form a laminate. A binder removal treatment is performed at 250 ° C. in an air atmosphere. Then under the air atmosphere 9
Baking at 00 to 950 ° C. (holding for 2 hours) to obtain a target substrate.

The amount of warpage of each of the obtained substrates (the maximum value of the amount of protrusion from the reference surface of the substrate; see FIG. 2) is measured using a surface roughness meter. The results are also shown in Table 7.

[0067]

[Table 7]

In the sample Nos. 21 to 26 which are examples using the calcined powder that precipitates Sr ₂ MgSi ₂ O ₇ crystals, the warpage amount is as good as 50 μm or less. On the other hand, in the sample No. 26, which is a comparative example using a calcined powder that precipitates Sr ₂ MgSi ₂ O ₇ crystals at the stage when the final sintered body is formed, the warpage amount is 1000 μm or more.

[0069]

According to the present invention, it is possible to obtain a wiring board with a built-in capacitor which can be densified at a temperature of 1000 ° C. or less and has excellent dielectric characteristics in a high frequency range. Also, A
There is an advantage that warping of the substrate hardly occurs even when co-firing with a low-resistance metal such as g or Cu. Since the content of the liquid phase component is small, the liquid phase component does not float on the wiring surface, and excellent solder wettability can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a wiring board with a built-in capacitor used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method for measuring the amount of warpage of a wiring board with a built-in capacitor.

FIG. 3 is an X-ray diffraction chart of Sample No. 8 as an example (unit of horizontal axis 2θ is [deg] converted to [rad]).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Built-in capacitor wiring board 2 Insulator layer 3 Capacitor part 4 Wiring layer 5 Via hole conductor 6 Dielectric layer 7 Electrode for capacitor

Continued on the front page (72) Inventor Junichi Ito 14-18 Takatsuji-cho, Mizuho-ku, Nagoya City, Aichi Prefecture Inside Japan Special Ceramics Co., Ltd. (72) Inventor Motohiko Sato, 14-18 Takatsuji-cho, Mizuho-ku, Nagoya City, Aichi Prefecture Inside the Special Ceramics Co., Ltd. (72) Inventor Satoshi Iio 14-18 Takatsuji-cho, Mizuho-ku, Nagoya City, Aichi Prefecture Inside Japan Special Ceramics Co., Ltd. (72) Kazushige Obayashi 14, 14 Takatsuji-cho, Mizuho-ku, Nagoya City, Aichi Prefecture No. 18 F Term in Japan Special Ceramics Co., Ltd. (Reference) 4G030 AA01 AA07 AA09 AA35 AA37 BA09 BA12 CA03 CA08 GA27 5E346 AA12 AA13 AA15 AA36 BB01 BB20 CC18 CC32 CC39 DD02 EE24 EE27 EE29 GG04 GG08 GG09 HH11H06

Claims (7)

[Claims] 1. A capacitor part comprising: a dielectric layer; capacitor electrodes formed on upper and lower surfaces of the dielectric layer to form a capacitor; and a capacitor formed to sandwich the dielectric layer and the capacitor part. A wiring board with a built-in capacitor, comprising: a low-temperature fired porcelain composition containing a Sr ₂ MgSi ₂ O ₇ crystal as a main crystal. 2. The wiring board with a built-in capacitor according to claim 1, wherein the insulator layer contains an SiO ₂ crystal as a sub crystal. 3. The Sr ₂ Mg contained in the insulator layer
_{3. The} wiring board with a built-in capacitor according to claim 2, wherein the weight ratio of the SiO ₂ -based crystal to the Si ₂ O ₇ crystal is 2.33 or less. 4. The wiring with a built-in capacitor according to claim 1, wherein the insulator layer contains a ceramic component, a boron component, and an alkali metal component as subcomponents. substrate. 5. The main crystal Sr ₂ Mg contained in 100% by mass of a low-temperature fired porcelain composition constituting the insulator layer.
V (mass%) is the mass% of the Si ₂ O ₇ crystal, W (mass%) is the mass% of the SiO ₂ crystal as the sub-crystal, and X is the mass% of the ceramic component in terms of oxide.
(Mass%), the mass% of the boron component in terms of oxide is Y (mass%), and the mass% of the alkali metal component in terms of oxide is Z
5. The wiring board with a built-in capacitor according to claim 4, wherein in the case of (% by mass), V to Z have an insulator layer satisfying the following relationship. 30 ≦ V ≦ 99.7 (% by mass), W ≦ 69.7 (% by mass), 0.1 ≦ X ≦ 10 (% by mass), 0.1 ≦ Y ≦ 10
(% By mass), 0.1 ≦ Z ≦ 10 (% by mass) 6. The insulator layer having a major axis of 0.1 to 20 μm.
6. The wiring board with a built-in capacitor according to claim 1, comprising at least 30% by mass of Sr ₂ MgSi ₂ O ₇ crystal particles. 7. The calcined powder containing at least one of Sr ₂ MgSi ₂ O ₇ crystal, SrSiO ₃ crystal and MgSiO ₃ crystal as a main component in an amount of 70 to 99.7% by weight of the calcined powder, 0.1 to 10% by weight (calculated as oxide) of the ceramic component, 0.1 to 10% by mass (calculated as oxide) of the boron component, and 0.1 to 10% by mass of the alkali metal component
7. A low-temperature fired porcelain composition obtained by mixing and molding (in terms of oxide) a green sheet or a laminate thereof, which is fired at a temperature in the range of 850 to 1000 [deg.] C. Wiring board with built-in capacitor.