JPH0832242A - Multilayer wiring board incorporating capacitor - Google Patents

Abstract

PURPOSE:To obtain a multilayer wiring board incorporating a capacitor part having a dielectric layer containing a lead based perovskite compound in which the permittivity of dielectric layer is prevented from lowering at the time of firing by interposing a buffer layer between the capacitor part and each glass ceramic composite board. CONSTITUTION:A dielectric layer 2 is sandwiched by electrode layers 31, 32 to constitute a capacitor part which is sandwiched by glass ceramic composite boards 41, 42. The glass ceramic composite boards 41, 42 are provided, on the outer surface with terminal electrodes 51, 52 which are connected, respectively, with the electrode layers 31, 32 through conductors filled in through holes 61, 62. Furthermore, buffer layers 71, 72 are provided, respectively, between the glass ceramic composite boards 41, 42 and the electrode layers 31, 32. Since the glass component is substantially blocked by the buffer layers 71, 72, decomposition of a lead based perovskite compound is retarded and high permittivity is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board having a capacitor section.

[0002]

2. Description of the Related Art In order to increase the density of wiring on a circuit board, it has been proposed to incorporate a capacitor in a multilayer wiring board {Electroceramic vol. 18, No. 5 (1987).
Year)}. When manufacturing such a multilayer wiring board, it is necessary to simultaneously bake the conductor material, the dielectric material and the board material. Since the firing temperature at this time is usually lower than the melting point of the conductor material, the characteristics are good and the cost is low, but the melting point is low.
When g or Ag-Pd is used as the conductor material, it is necessary to use a glass-ceramic composite substrate material having a low firing temperature. The glass-ceramic composite substrate material is Al ₂
In addition to aggregates such as O ₃ , glass powder is contained, and in order to lower the softening point and improve the wettability with respect to aggregates, this glass powder is described in, for example, JP-A-2-230606. As described above, the total content of SiO ₂ and B ₂ O ₃ is about 30% by weight or more. Further, in order to adjust the contraction rate of the conductor layer and prevent warpage, cracks, and delamination of the multilayer substrate, it is common to add glass powder to the conductor layer. This glass powder also has the function of improving the adhesiveness of the conductor layer. The glass powder contained in the conductor layer has an S composition close to that of the glass powder contained in the substrate in order to reduce the difference in coefficient of thermal expansion between the substrate and the conductor layer.
A material having a high iO ₂ content is used.

Although it is necessary to use a dielectric material having a high dielectric constant in order to make a small-sized and high-capacity capacitor, a lead-based perovskite compound has a high relative dielectric constant of 10,000 or more and can be co-fired with Ag. Therefore, it is expected. However, it is considered that the dielectric material is deteriorated because the high capacity as expected when the lead-based perovskite compound is actually applied to the built-in capacitor of the multilayer wiring board cannot be obtained.

[0004]

As a result of the research conducted by the present inventor, Si and B diffused from the glass powder contained in the substrate and the conductor during firing and penetrated into the dielectric layer. It was found that the perovskite compound was decomposed to form a pyrochlore-based compound having a low dielectric constant, which made it impossible to obtain a high dielectric constant.

An object of the present invention is to suppress dielectric constant deterioration of a dielectric layer during firing in a multilayer wiring board having a built-in capacitor portion having a dielectric layer containing a lead-based perovskite compound.

[0006]

Such an object is achieved by any of the following constitutions (1) to (6). (1) A capacitor part having a dielectric layer and an electrode layer is built in between a pair of glass-ceramic composite substrates, and a buffer layer is provided between the capacitor part and each glass-ceramic composite substrate. Contains a lead-based perovskite compound as a dielectric material, and the buffer layer contains a lead-based pyrochlore compound as a buffer material. (2) Pb ₃ Nb ₄ O ₁₃ as a lead-based pyrochlore compound
The multilayer wiring board with a built-in capacitor according to (1) above. (3) The multilayer wiring board with a built-in capacitor according to the above (1) or (2), which contains a complex oxide containing Pb, Mg and Nb as a lead-based pyrochlore compound. (4) Pb ₂ Mg _0.25 Nb _1.75 O _6.625 and Pb _1.83 as complex oxides containing Pb, Mg and Nb as constituent components.
Mg _0.29 Nb _1.71 O _6.39 , Pb ₂ Mg _0.06 Nb _1.94 O
_The multilayer wiring board with a built-in capacitor according to (3) above, which contains at least one selected from _6.91 and Pb ₂ Mg _0.16 Nb _1.84 O _6.76 . (5) The buffer layer contains CuO, V ₂ O ₅ and B as additives.
Containing at least one oxide selected from ₂ O ₃ ;
CuO + for 100 parts by weight of lead-based pyrochlore compound
The multilayer wiring board with a built-in capacitor according to any one of the above (1) to (4), wherein the content of V ₂ O ₅ + B ₂ O ₃ is 20 parts by weight or less. (6) The multilayered capacitor built-in according to any one of (1) to (5) above, wherein the buffer layer has an average coefficient of thermal expansion at 50 to 750 ° C. of 6.5 × 10 ^{−6 to} 10.0 × 10 ⁻⁶ / ° C. Wiring board.

[0007]

The multilayer wiring board to which the present invention is applied has a capacitor portion between a pair of glass-ceramic composite substrates, and the dielectric layer of this capacitor portion uses a lead-based perovskite compound as a dielectric material. Including. In the present invention, a buffer layer is provided between the capacitor section and each glass-ceramic composite substrate. The buffer layer is mainly composed of a lead-based compound having a pyrochlore structure which is extremely stable as compared with the perovskite structure. In the conventional multilayer wiring board with a built-in capacitor, the glass component (especially S
i and B) were diffused and the lead-based perovskite compound in the dielectric layer was decomposed to cause the deterioration of the dielectric constant. However, in the present invention, the glass component is almost blocked by the buffer layer,
Decomposition of the lead-based perovskite compound is suppressed, and the original high dielectric constant is obtained.

Incidentally, Japanese Patent Laid-Open No. 3-45584 discloses that
Since a low-temperature fired ceramic circuit board contains a large amount of glass components, it is stated that if the electrodes are not dense when incorporating a capacitor, the glass components in the circuit board material will diffuse into the dielectric and reduce the dielectric constant. is there. Then, in order to prevent the diffusion of the glass component, the conductive material for the electrode is
It is proposed to include l ₂ O ₃ for densification. However, in this publication, since zinc borosilicate glass is used as the glass powder to be contained in the conductor material, the dielectric material is deteriorated due to the diffusion of Si and B from the glass powder. In addition, SiO ₂ + B of zinc borosilicate glass
_{The 2} O ₃ content is usually about 30 to 70% by weight.

[0009]

Specific Structure The specific structure of the present invention will be described in detail below.

FIG. 1 shows a partial sectional view of the vicinity of a capacitor portion of a multilayer wiring board with a built-in capacitor. In the figure, the dielectric layer 2 is sandwiched between the electrode layers 31 and 32 to form a capacitor section, and the capacitor section is formed by the glass-ceramic composite substrate 4.
It is sandwiched between 1 and 42. Terminal electrodes 51, 5 are formed on the outer surfaces of the glass-ceramic composite substrates 41, 42, respectively.
2 are provided, and these terminal electrodes are connected to the electrode layers 31 and 32 by conductors filled in the through holes 61 and 62, respectively. Buffer layers 71 and 72 are provided between the glass-ceramic composite substrates 41 and 42 and the electrode layers 31 and 32, respectively.

The multilayer wiring board of the present invention is usually manufactured by a printing method or a sheet method. In the printing method, a cushioning material paste is printed on a green sheet of a glass-ceramic composite substrate having through holes, and then a conductor paste and a dielectric paste are alternately printed so that a predetermined number of laminated layers are obtained. After printing the paste, the green sheets of the glass-ceramic composite substrate are stacked and fired. On the other hand, in the sheet method, a laminated body in which a conductor paste is printed on a dielectric green sheet is produced, and a predetermined number of the laminated body is formed on a green sheet of a glass-ceramic composite substrate on which a buffer paste and a conductor paste are printed. After stacking and further printing the buffer material paste, the green sheets of the glass-ceramic composite substrate are stacked and fired. The cushioning material may be used as a green sheet. After firing, the terminal electrode paste is formed in a predetermined pattern on the surface of the glass-ceramic composite substrate and fired to form the terminal electrodes. The terminal electrode may be fired at the same time as the glass-ceramic composite substrate, the dielectric layer, or the like.

The cushioning material paste that becomes a cushioning layer by firing contains a cushioning material and a vehicle. In the present invention, a lead-based pyrochlore compound is used as the buffer material. Pb ₃ Nb ₄ O ₁₃ is preferably used as the lead-based pyrochlore compound. In addition, as a lead-based pyrochlore compound, P
A complex oxide containing b, Mg and Nb as constituent components is also preferable. As such a composite oxide, Pb ₂ Mg _{0.25
Nb 1.75 O 6.625, Pb 1. 83} Mg 0.29 Nb 1.71 O 6.39,
Pb ₂ Mg _0.06 Nb _1.94 O _6.91 and Pb ₂ Mg _{0. 16} N
At least one selected from b _1.84 O _6.76 is preferable, and these may be used in combination with Pb ₃ Nb ₄ O ₁₃ .

The average particle size of the lead-based pyrochlore compound powder in the paste is preferably 0.1 to 10 μm. If the average particle size is too small, the binder removal property will be poor, and if it is too large, the printability will be poor and dense sintering will be difficult, such being undesirable.

The buffer layer contains CuO and V ₂ O as additive materials.
It is preferable to include at least one oxide selected from ₅ and B ₂ O ₃ . The lead-based pyrochlore compound, which is a buffer material, is difficult to be densely sintered at about 950 ° C. or less, and thus is difficult to be co-fired with the conductor paste using Ag. However, by adding these additives, it becomes possible to perform dense sintering at low temperature. Moreover, by adding these additives, lead-based perovskite compound in the dielectric layer, in particular _{Pb (Mg 1/3 Nb 2/3} ) O 3
Since the sintering behavior can be matched, both layers can be densely sintered. Also, it becomes easy to match the sintering behavior with the glass-ceramic composite substrate.

In the buffer layer, the ratio of these additives to 100 parts by weight of the lead-based pyrochlore compound is as follows. CuO is preferably 20 parts by weight or less,
It is more preferably 0.5 to 10 parts by weight. If the amount of CuO is too small, the effect of the addition becomes insufficient, and if it is too large, foaming easily occurs and the strength of the multilayer wiring board deteriorates.
It becomes difficult to handle. V ₂ O ₅ is preferably 10 parts by weight or less, more preferably 0.3 to 5 parts by weight. V ₂
If the amount of O ₅ is too small, the effect of the addition becomes insufficient, and if it is too large, it reacts with the conductor or diffuses to deteriorate the insulating property of the dielectric layer, which is not preferable. B ₂ O ₃ is preferably 10 parts by weight or less, preferably 0.3 to 5 parts by weight. If the amount of B ₂ O ₃ is too small, the effect of addition becomes insufficient, and if it is too large, the lead-based perovskite compound in the dielectric layer is decomposed by diffusion. When adding two or more kinds, CuO + V ₂ O ₅ + B ₂ O ₃ is preferably 20 parts by weight or less, more preferably 10 parts by weight or less. If there is too much CuO + V ₂ O ₅ + B ₂ O ₃ ,
Inconveniences such as foaming and deterioration of insulation occur.

The average particle size of these additives in the paste is preferably 0.01 to 5 μm. If the average particle size is too small, it will be difficult to uniformly disperse, and if it is too large, the effect as a sintering aid will be reduced, and
It becomes difficult to disperse it uniformly.

The buffer layer may contain, for example, a lead-based perovskite compound or the like in addition to the lead-based pyrochlore compound and the additive, but the lead-based pyrochlore compound and the additive are combined in the buffer layer. It preferably accounts for 50% by weight or more.

The vehicle contained in the buffer paste contains a binder and a solvent. Examples of the binder include ethyl cellulose, polyvinyl butyral, methacrylic resin and butyl methacrylate, and examples of the solvent include terpineol, butyl carbitol, butyl carbitol acetate, toluene, alcohol and xylene. In addition to these, various dispersants, activators, plasticizers and the like are added to the vehicle as needed.
The content of the vehicle in the paste is preferably about 10 to 20% by weight.

The thickness of the buffer layer is preferably 10-100.
μm, more preferably 20 to 50 μm. If the buffer layer is too thin, the protective effect of the dielectric layer will be insufficient. on the other hand,
If the buffer layer is too thick, the multilayer wiring board becomes thicker and it becomes difficult to miniaturize, and the merit as an integrated device is lost.

The dielectric paste that forms a dielectric layer by firing contains a dielectric material and a vehicle. In the present invention,
A lead-based perovskite compound is used as the dielectric material.
Among lead-based perovskite compounds, Pb (Mg _1/3 Nb
_2/3 ) O ₃ , Pb (Fe _1/2 W _1/2 ) O ₃ , Pb (Fe
_1/2 Nb _1/2 ) O ₃ and Pb (Zn _1/3 Nb _2/3 ) O
_{Since 3} is particularly easily decomposed, the effect of the present invention is particularly high when at least one of these is used. The total content of these compounds with respect to the entire lead-based perovskite compound is preferably 80% by weight or more. In addition to these, PbTiO ₃ , CuO or the like may be used in combination.
PbTiO ₃ raises the Curie temperature, and CuO improves sinterability. A dielectric material other than the lead-based perovskite compound may be used in combination, but the lead-based perovskite compound is preferably 70% by weight or more of the entire dielectric material.

The average particle size of the dielectric material is preferably 0.
It is 1 to 10 μm. If the average particle size is too small, the binder removal property deteriorates, and if it is too large, the sinterability deteriorates.
Sintering becomes difficult at about 0 ° C or lower.

As the vehicle of the dielectric paste, those mentioned in the explanation of the buffer paste may be used.

The thickness of the dielectric layer may be appropriately determined according to the intended capacity and the like, but is preferably 20 to 50 μm.
m. If the dielectric layer is too thin, it becomes difficult to form a uniform layer. On the other hand, if the dielectric layer is too thick, the multilayer wiring board becomes thick and it becomes difficult to miniaturize it.

In the present invention, a glass-ceramic composite substrate containing an oxide aggregate and glass is used for simultaneously firing the conductor paste mainly containing Ag and the substrate green sheet.

The substrate material which becomes a glass-ceramic composite substrate by firing contains oxide aggregate and glass powder. The glass powder used as the substrate material is not particularly limited,
It may have an ordinary composition conventionally used for glass-ceramic composite substrates. Examples of such glass powder include SiO ₂ —SrO—Al ₂ O ₃ —B ₂ O ₃ disclosed in JP-A-1-132194.
-CaO-BaO type glass etc. are mentioned. Specifically, in consideration of improving the bending strength of the glass-ceramic composite substrate, the wettability to the oxide aggregate, the adhesiveness to the terminal electrode, etc., for example, a glass having a softening point of about 750 to 850 ° C. may be appropriately selected. Good.

However, in order to further suppress the deterioration of the lead-based perovskite compound in the dielectric layer, a part or all of the glass powder contained in the glass-ceramic composite substrate is the same as the glass powder preferably used in the conductor paste described later. In addition, glass powder having a SiO ₂ + B ₂ O ₃ content of 20% by weight or less may be used.

The average particle size of the glass powder is not particularly limited, but in consideration of moldability and the like, one having a particle size of about 1 to 3 μm is usually used.

The glass powder content of the entire substrate material is preferably 50 to 80% by weight. If the amount of glass powder is too small, the sinterability tends to deteriorate, and if it is too large, the bending strength of the glass-ceramic composite substrate tends to decrease.

Examples of oxide aggregates include Al ₂ O ₃ and
Forsterite, quartz, mullite, cordierite,
R ₂ Ti ₂ O ₇ (R is one or more of lanthanoid elements),
Ca ₂ Nb ₂ O ₇ , MgTiO ₃ , SrZrO ₃ , Ti
O ₂ , SnO ₂ · TiO ₂ , ZrTiO ₄ , Ba ₂ Ti
₉ O ₂₀ , Sr ₂ Nb ₂ O ₇ , CaTiO ₃ , SrTiO
₃ , SrSnO ₃ , BaO · R ₂ O ₃ · nTiO ₂ (R
Is one or more of lanthanoid elements) and the like. In this case, the oxide aggregate to be used may have a composition slightly deviated from the stoichiometric composition, a mixture with a composition deviated from the stoichiometric composition, or a mixture of compounds having a composition deviated from each other. Further, various oxides such as Bi ₂ O ₃ , MnO and CuO may be further added.

A preferred combination of glass powder and oxide aggregate is disclosed in, for example, JP-A-1-132194, that is, Al ₂ O ₃ components 30-5.
0% by weight and 70 to 50% by weight of a glass component, and the glass component is SiO ₂ 46 to 60% by weight, B ₂ O ₃
0.5-5% by weight, Al ₂ O ₃ 6-17.5% by weight and alkaline earth metal oxides 25-45% by weight, at least 60% by weight in said alkaline earth metal oxides. Is a combination of SrO. Further, the following two kinds of combinations disclosed in Japanese Patent Application No. 6-87859 are also preferable. In the first combination, as aggregate, at least KAlSiO ₄ and / or KAlS
with i ₂ O _6, as the glass powder, KAlSi during firing
Of a composition that does not decompose O ₄ and KAlSi ₂ O ₆ ,
For example, 25 to 60 wt% of SiO ₂ and 6 of Al ₂ O ₃ are used.
-20% by weight, at least one of the alkaline earth metal oxides
A seed containing a total of 20 to 50% by weight is used. In the second combination, KAlSiO ₄ and KAl are used as aggregates.
A composition in which at least one of Si ₂ O ₆ and Al ₂ O ₃ is used and KAlSiO ₄ and / or KAlSi ₂ O ₆ is precipitated by crystallization as glass powder, for example,
25 to 60% by weight of SiO ₂ , 6 to 20% by weight of Al ₂ O ₃ , 20 to 50% by weight of at least one kind of alkaline earth metal oxide, and 6 to 15% by weight of K ₂ O. To use. In the combination disclosed in Japanese Patent Application No. 6-87859, the glass-ceramic composite substrate has a coefficient of thermal expansion (average of 50 to 750 ° C.) of 8.0 × 10 ^{−6 to} 19.
It can be set to 5 × 10 ⁻⁶ / ° C., and can be brought close to the thermal expansion coefficient of the dielectric layer mainly containing the lead-based perovskite compound.

The average particle size of the oxide aggregate is generally 0.5 to
It is preferably about 3 μm. If the average particle diameter is too small, it tends to be difficult to form a sheet, and if it is too large, the strength of the glass-ceramic composite substrate tends to be insufficient.

A vehicle is added to the oxide aggregate and the glass powder to form a slurry, and the slurry is molded and dried to form a green sheet. As the vehicle, those mentioned in the explanation of the cushioning material paste may be used.

The thickness of the glass-ceramic composite substrate is
It is preferably 30 to 200 μm. If the glass-ceramic composite substrate is too thin, the bending strength becomes insufficient and handling becomes difficult, and if it is too thick, the binder removal property deteriorates.

The conductor paste which becomes the electrode layer by firing is
Although it contains a conductor powder and a vehicle, it may contain glass powder if necessary.

Since the conductor powder has good conductivity and is inexpensive, Ag particles or a mixture of Ag particles and Pd particles are used, or Ag--Pd alloy particles or A particles thereof are used.
It is preferable to use a mixture of g particles and / or Pd particles. The content of each metal with respect to the entire conductor powder is Ag: 80 to 100% by weight, Pd: 0 to 20.
It is preferably in the weight%. If the Ag content is too low, the resistance will increase. Pd is not essential, but the inclusion of Pd reduces Ag migration, and
The inclusion of Pd increases the firing temperature of the conductor paste, which is effective when the firing temperature of the buffer paste is relatively high. The average particle diameter of the conductor powder (the average of the major axis diameters when the particle shape has anisotropy) is not particularly limited, but usually 0.
It may be about 1 to 5 μm. The particle shape is not particularly limited, but generally spherical shape is preferable. However, some or all of the conductor particles may be scale-shaped.

The glass powder is added to the conductor paste as needed to prevent warpage of the multilayer wiring board, cracks, and adhesion of the electrode layers. The composition of the glass powder is not particularly limited, but in order to suppress deterioration of the dielectric layer containing the lead-based perovskite compound during firing, SiO ₂
It contains the SiO ₂ and B ₂ O ₃ or containing, SiO ₂
A glass powder having a total content and a B ₂ O ₃ content of preferably 20% by weight or less, more preferably 12% by weight or less is used. If the content of SiO ₂ + B ₂ O ₃ is too high, the lead-based perovskite compound is adversely affected, and the dielectric constant deterioration of the dielectric material particularly near the interface with the electrode layer becomes severe. SiO ₂ is essential for vitrification, and the preferred content is 3% by weight or more, and the more preferred content is 5% by weight or more. In this specification, the compound contained in the glass is represented as a stoichiometric composition such as SiO ₂ or B ₂ O ₃ , but in the glass, the stoichiometric composition ratio may be slightly deviated, This also applies to the above-mentioned cushioning material, additive material, dielectric material, aggregate material, and the like. S
The compound contained in the glass powder other than iO ₂ and B ₂ O ₃ is not particularly limited, but is usually alumina, titania,
It is preferably at least one selected from oxides of alkaline earth metal elements, lead oxides and bismuth oxides, and particularly preferably oxides of alumina, titania and alkaline earth metal elements. As the alkaline earth metal element, Sr, Ba, Ca, Mg or the like is preferable.
The preferred content of each compound is alumina: 5 to 15% by weight, titania: 20 to 35% by weight, oxide of alkaline earth metal element: 40 to 65% by weight, lead oxide + bismuth oxide: 30% by weight or less. is there. A part of the oxide of the alkaline earth metal element may be replaced with tin oxide, and the substitution rate in this case is preferably 50% by weight or less of the oxide of the alkaline earth metal element. Zirconia may be added, but the addition amount is preferably 5% by weight or less.

As described above, a glass having a low SiO ₂ + B ₂ O ₃ content generally has a low crystallization temperature, and is usually 1000
Crystallization starts below ℃. Therefore, the glass powder usually crystallizes during firing. The crystallization temperature of the glass powder having the above composition is usually about 800 to 950 ° C. Even if the glass powder does not crystallize during firing, SiO ₂ + B ₂ O ₃
The effect of lowering the content is realized.

When glass powder is added, the ratio of glass powder to the total of conductor powder and glass powder in the conductor paste is preferably 1 to 20% by weight, more preferably 3%.
-15% by weight. If the ratio of glass powder is too low, the effect of adding glass powder becomes insufficient. If the ratio of the glass powder is too high, the electrode layer will not be dense, which is not preferable.

The average particle size of the glass powder is not particularly limited, but it is usually about 0.5 to 3 μm.

Two or more kinds of glass powders having different compositions may be used together. In this case, it is preferable that all of the glass powder has a low composition of the SiO ₂ + B ₂ O ₃ content above, SiO ₂ a part of the glass powder is more than 20 wt%
+ B ₂ O ₃ may be contained. However, the content of SiO ₂ + B ₂ O _{3 in the} entire glass powder is preferably 20% by weight or less.

The above-mentioned SiO ₂ + B ₂ O was added to the conductor paste.
₃ By using glass powder having a low content rate, adverse effects on the dielectric layer can be reduced, but it is preferable to form the electrode layer of the capacitor section by using a conductor paste containing no glass powder. A conductor paste containing glass powder may be used for the internal conductors other than this electrode layer. For example, in the multilayer wiring board shown in FIG.
82 contains glass, and the electrode layer 3 does not contain glass.
1, 32 are connected to the internal conductors 81, 82 by through holes 61, 62, respectively.

As the vehicle of the conductor paste, the ones mentioned in the explanation of the buffer paste may be used.

Although the thickness of the electrode layer is not particularly limited, it is usually about 3 to 20 μm.

The firing may be usually performed in the air. The firing temperature is preferably 800 ° C. or higher, and specifically, it may be appropriately determined depending on the composition of the conductor powder and the composition of the buffer layer. When the above-mentioned buffer material is used, the firing temperature is 1200 ° C. or lower. It is possible to perform firing at 1000 ° C. or lower by using the additive. The firing time is usually 2 to 12
It is about time. The firing may be performed multiple times.

In the illustrated example, there is only one dielectric layer,
A structure in which two or more dielectric layers are provided may be used.

The dielectric layer may contain glass powder having a SiO ₂ + B ₂ O ₃ content of 20% by weight or less. By including such glass powder in the dielectric layer, it is possible to lower the sintering temperature of the lead-based perovskite compound dielectric and to suppress adverse effects on the dielectric material. As the glass powder contained in the dielectric layer, PbO—Bi ₂ O ₃ —SiO ₂ -based powder is preferable.

In the present invention, the average coefficient of thermal expansion of the buffer layer at 50 to 750 ° C. is 6.5 × 10 ^{−6 to} 10.0 × 10 ^−6.
/ ° C. On the other hand, in the above-mentioned glass-ceramic composite substrate, the average coefficient of thermal expansion at 50 to 750 ° C. is generally 5.5 × 10 ^{−6 to} 14.5 × 10 ⁻⁶ / ° C.
Further, in the dielectric layer containing the lead-based perovskite compound, the average coefficient of thermal expansion at 50 to 750 ° C. is generally 8.0 × 10 ^{−6 to} 10.0 × 10 ⁻⁶ / ° C. In this way, since the difference in the coefficient of thermal expansion between the respective parts of the multilayer wiring board can be reduced, defects such as warpage and cracks are less likely to occur during cooling after firing.

[0048]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

A multilayer wiring board having the structure shown in FIG. 1 was manufactured as follows.

<Green Sheet for Glass-Ceramics Composite Substrate> 40 parts by weight of Al ₂ O ₃ and 60 parts by weight of SiO ₂ —SrO—Al ₂ O ₃ —B ₂ O ₃ type glass powder (SiO ₂ + B ₂ O _3). A vehicle was added to the content of 55% by weight), and the mixture was kneaded, formed into a sheet by the doctor blade method, and then dried to prepare a green sheet having a thickness of about 250 μm. The vehicle, acrylic resin as a binder, ethyl alcohol and toluene as a solvent,
Phthalates were used as plasticizers. Through holes were punched in this green sheet by punching.
Further, a green sheet for high temperature firing was also prepared by using glass powder having a higher softening point by further increasing the contents of SiO ₂ and Al ₂ O ₃ .

<Conductor paste> Conductor powder (average particle size 3.5
Vehicle was added to (μm Ag powder) and kneaded with a three-roll mill to form a paste. The vehicle used acrylic resin as a binder and terpineol and butyl carbitol acetate as a solvent. In addition, a conductor paste for high-temperature firing was also prepared in which Ag 80 wt% -Pd 20 wt% alloy powder was used as the conductor powder.

<Dielectric paste> 95 as a dielectric material
Mol% Pb (Mg _1/3 Nb _2/3 ) O ₃ -5 mol% PbT
iO ₃ (average particle size 1.0 μm) and this dielectric material 10
CuO powder in an amount of 0.3 parts by weight relative to 0 parts by weight and the vehicle used for the conductor paste were kneaded in a three-roll mill to form a paste.

<Cushioning Material Paste> A buffering material was manufactured by the following method.

Synthesis of Pb ₃ Nb ₄ O ₁₃ PbO: Nb ₂ O ₅ = 3: 2 (molar ratio). Mix in a fryer and mix in a ZrO ₂ bowl with a lid. It was baked at 700 ° C. for 2 hours. After roughly pulverizing the fired product, it was wet pulverized with a ball mill for 20 hours and dried. The dried product was analyzed by X-ray diffraction to find that Pb of the pyrochlore structure
_{A 3} Nb ₄ O ₁₃ phase was confirmed.

Synthesis of Pb ₂ Mg _0.25 Nb _1.75 O _6.625 PbO: MgO: Nb ₂ O ₅ = 16: 2: 7 (molar ratio)
Mix with a squeegee machine to produce Z with a lid.
The mixture was baked at 800 ° C. for 2 hours in a rO ₂ container. After roughly pulverizing the fired product, it was wet pulverized with a ball mill for 20 hours and dried. The dried product was analyzed by X-ray diffraction to confirm the pyrochlore phase.

Synthesis of Pb _1.83 Mg _0.29 Nb _1.71 O _6.39 PbO: MgO: Nb ₂ O ₅ = 1.83: 0.29:
Mix to a molar ratio of 0.855 and mix with a squeegee machine, and then mix in a ZrO ₂ container with a lid at 800 ° C for 2
Burned for hours. After roughly crushing the fired product, use a ball mill to
It was wet-milled for 0 hours and dried. The dried product was analyzed by X-ray diffraction to confirm the pyrochlore phase.

Synthesis of Pb ₂ Mg _0.06 Nb _1.94 O _6.91 PbO: MgO: Nb ₂ O ₅ = 2: 0.06: 0.97
(Mole ratio)
Baking was performed at 800 ° C. for 2 hours in a ZrO ₂ container with a lid. After roughly pulverizing the fired product, it was wet pulverized with a ball mill for 20 hours and dried. The dried product was analyzed by X-ray diffraction,
The pyrochlore phase was confirmed.

Synthesis of Pb ₂ Mg _0.16 Nb _1.84 O _6.76 PbO: MgO: Nb ₂ O ₅ = 2: 0.16: 0.92
(Mole ratio)
Baking was performed at 800 ° C. for 2 hours in a ZrO ₂ container with a lid. After roughly pulverizing the fired product, it was wet pulverized with a ball mill for 20 hours and dried. The dried product was analyzed by X-ray diffraction,
The pyrochlore phase was confirmed.

The average particle size of each of the buffer materials was 1.0 μm. The vehicle used for the conductor paste was added to each buffer material and kneaded with a three-roll mill to form a paste. A paste was also prepared in which an additive was added to the buffer material powder. The average particle size of the additive was 0.3 μm. Table 1 shows the amount of the additive material added to 100 parts by weight of the buffer material.

Next, a buffer material paste, a conductor paste, a dielectric paste, a conductor paste and a buffer material paste were sequentially printed on the green sheet for glass-ceramic composite substrate by a screen printing method, and then the glass-
Green sheets of the ceramic composite substrate were stacked and pressed by hot pressing, and then fired for 2 hours to obtain a multilayer wiring substrate sample. The firing temperature is shown in Table 1. This temperature was maintained for 10 minutes during firing. The above-mentioned green sheet for high-temperature firing and the conductor paste for high-temperature firing were used for the samples whose firing temperature exceeded 900 ° C. The buffer layer of each sample had a thickness of 30 μm, the electrode layer had a thickness of 15 μm, and the dielectric layer had a thickness of 30 μm.

Next, the outer conductor paste is printed on the outer surface of the fired body by a screen printing method, and the outer conductor paste is heated to 850 in air.
It was baked at 10 ° C. for 10 minutes to obtain a multilayer wiring board sample with a built-in capacitor section.

Other than the above, a comparative sample (Sample No. 1) was prepared in the same manner as the above sample except that the buffer layer was not formed.
1) was produced.

[0063]

[Table 1]

From the results shown in Table 1, it is understood that when the additive is added, the temperature at which dense sintering is possible becomes low.

A cross section of the sample was taken by a scanning electron microscope (SE
M) and electron probe X-ray microanalysis (E
As a result of observation by PMA), in the sample of the present invention, almost no diffusion of the glass component, particularly Si into the dielectric layer was observed, and both the dielectric layer and the buffer layer could be densely sintered.

On the other hand, in the comparative sample having no buffer layer, a large amount of glass was diffused in the dielectric layer.
A large amount of Pb derived from the dielectric material penetrated into the diffused glass, and penetration of Nb and Mg was also recognized. Further, columnar crystals containing Si and Mg as main components were recognized in the diffused glass. Also, in the comparison sample,
Pyrochlore compound (Pb _1.83 Mg _0.29 N in the dielectric layer)
b _1.71 O _6.39 ) is generated by X-ray diffraction and E
Although confirmed by PMA, in the sample of the present invention, formation of a pyrochlore compound was not observed in the dielectric layer. In the sample of the present invention, diffusion of Si, which is the glass component of the substrate, was observed in the buffer layer. The diffusion depth was about 10 μm to 20 μm from the substrate side.

The dielectric paste used for each sample, the buffer paste used for sample No. 2 and the buffer paste used for sample No. 7 were dried and powdered,
Each powder was molded at a pressure of 1 t / cm ² to form a prism having a length of 10 mm, and the shrinkage behavior was examined by thermomechanical analysis. The result is shown in Figure 3.
Shown in The vertical axis of the graph in FIG. 3 is the expansion coefficient, and this expansion coefficient is the ratio (ΔL / L) of the length change amount ΔL at each temperature to the length L at 22 ° C. From FIG. 3, it can be seen that by adding V ₂ O ₅ to the buffer material, the shrinkage behavior becomes almost the same as that of the dielectric material. Note that C
Even when uO or B ₂ O ₃ was added, the same shrinkage behavior as when V ₂ O _{5 was} added was exhibited.

In the samples of the present invention shown in Table 1, 50 to 75
The average thermal expansion coefficient at 0 ° C. is 7.4 × 10 ^{−6 for the} buffer layer.
˜10.0 × 10 ⁻⁶ / ° C., glass-ceramic substrate 9.9 × 10 ⁻⁶ / ° C., dielectric layer 9.0 × 10 ⁻⁶ / ° C., difference in thermal expansion coefficient is a problem. It wasn't that big.

Glass powder consisting of SiO ₂ = 6.97% by weight, BaO = 53.39% by weight, TiO ₂ = 27.81% by weight, Al ₂ O ₃ = 11.83% by weight was added to the conductor paste. Then, when a multilayer wiring board sample was prepared in the same manner as the sample of the present invention in Table 1, a decrease in the dielectric constant of the dielectric layer was hardly recognized as compared with the case where glass powder was not added.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a configuration example of a multilayer wiring board having a built-in capacitor section.

FIG. 2 is a partial cross-sectional view showing a configuration example of a multilayer wiring board having a built-in capacitor section.

FIG. 3 is a graph showing shrinkage behavior during firing for each of the buffer layer and the dielectric layer.

[Explanation of symbols]

 2 Dielectric layer 31, 32 Electrode layer 41, 42 Glass-ceramic composite substrate 51, 52 Terminal electrode 61, 62 Through hole 71, 72 Buffer layer 81, 82 Internal conductor

Claims (6)

[Claims] 1. A capacitor part having a dielectric layer and an electrode layer is built in between a pair of glass-ceramic composite substrates, and a buffer layer is provided between the capacitor part and each glass-ceramic composite substrate. A multilayer wiring board with a built-in capacitor, wherein the body layer contains a lead-based perovskite compound as a dielectric material, and the buffer layer contains a lead-based pyrochlore compound as a buffer material. 2. Pb ₃ N as a lead-based pyrochlore compound
The multilayer wiring board with a built-in capacitor according to claim 1, containing b ₄ O ₁₃ . 3. Pb, M as a lead-based pyrochlore compound
The multilayer wiring board with a built-in capacitor according to claim 1 or 2, comprising a complex oxide containing g and Nb as constituent components. 4. Pb ₂ Mg _0.25 Nb _1.75 O _6.625 , which is a composite oxide containing Pb, Mg and Nb as constituent components.
Pb _1.83 Mg _0.29 Nb _1.71 O _6.39 , Pb ₂ Mg _0.06 Nb
_{4. The} multilayer wiring board with a built-in capacitor according to claim 3, containing at least one selected from _1.94 O _6.91 and Pb ₂ Mg _0.16 Nb _1.84 O _6.76 . 5. A buffer layer containing CuO or V ₂ O ₅ as an additive.
And B comprises a ₂ O ₃ of at least one oxide selected from the content of _{CuO + V 2 O 5 + B} 2 O 3 with respect to lead-based pyrochlore compounds 100 parts by weight of claims 1 to 4 20 parts by weight or less A multilayer wiring board with a built-in capacitor. 6. The multilayer wiring with a built-in capacitor according to claim 1, wherein the buffer layer has an average coefficient of thermal expansion of 6.5 × 10 ^{−6 to} 10.0 × 10 ⁻⁶ / ° C. at 50 to 750 ° C. substrate.