JPH07326540A - Multilayer capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a multilayer capacitor with high Q factor in the high frequency region, by using a dielectric layer made of glass and oxide base material and an inner electrode layer made of glass and Ag-based conductor, and specifying a ratio of glass weight in the inner electrode layer. CONSTITUTION:A laminate capacitor includes a capacitor chip that is formed by laminating a dielectric layer and an inner electrode layer. The dielectric layer includes glass composite material made up of oxide base material and glass. The inner electrode layer is made of the Ag-based conductor and glass, and a ratio of glass is 5 to 20wt.% to the total weight of glass and conductor. Since the conductor in the inner electrode layer is mainly made of Ag-based material with low resistivity, the laminated capacitor has a high Q factor high frequency region of 100MHz to 2GHz. In addition, a burning step an be carried out in air without accurate atmosphere control, and the productive cost can be reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to multilayer capacitors, and in particular to
The present invention relates to a multilayer capacitor having a high Q at 100 MHz or higher and excellent reliability, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, CaTiO ₃ and MgTi are used as dielectric materials for multilayer capacitors used in a high frequency range.
Titanate-based materials such as O ₃ are used. However, these titanate-based materials have a high sintering temperature of about 1200 ° C. In a multilayer capacitor in which the internal electrode layers must be fired at the same time as the dielectric layers, the melting point of the conductor used for the internal electrode layers must be higher than the firing temperature. Usually, Pd is used.

On the other hand, in recent years, there has been a great demand for higher frequencies for elements, and multilayer capacitors from 100 MHz to 2
It is being used in the GHz range.

In the case of a conventional multilayer capacitor using Pd as a conductor, a Q value sufficient for actual use can be obtained at a frequency of less than 100 MHz, but a sufficient Q value cannot be secured in a frequency range of 100 MHz or more. In some cases, the degree of freedom in design may be restricted due to a problem or the necessity of designing a circuit in consideration of the low Q value.

Generally, the Q value of a capacitor is defined by the angular frequency ω
(Rad · Hz), capacitance is C (F), dielectric loss is D (dimensionless), and inductance parasitic in the element is L
(H) and the equivalent series resistance is R (Ω), it is expressed by the formula Q = (1−ω ² LC) / (ωCR + D). From this equation, if the capacitance C and the inductance L are constant, the Q value is governed by the dielectric loss D in the low frequency region and the equivalent series resistance R in the high frequency region.

Since the specific resistance of Pd is one digit higher than that of Ag or Cu, it is preferable to use Ag or Cu for the internal electrodes in order to obtain high Q at high frequencies. Examples of improving Q at high frequencies by using a metal having a low specific resistance so far include, for example, the following documents and.

I.Burn and WCPorter, "Processing
Multilayer Ceramics with Internal Copper Conducto
rs ", 375, Materials and Processes for Microelectroni
c System, Ceramic Transaction, Vol.15, KMNair,
R. Pohanka and RC Buchanan, Am. Ceram. Soc., USA,
(1990).

H. Mandai, Y. Skabe and JPCanne
r, "Multilayer Ceramic NPO Capacitors with Copper E
lectrode ", 313, Materials and Processes for Microele
ctronic System, Ceramic Transaction, Vol.15, KMN
air, R. Pohanka and RCBuchanan, Am. Ceram. Soc.,
USA, (1990).

In the above-mentioned documents and the above, C is used as the internal electrode layer.
Although a high Q in a high frequency region is realized by using u, Cu is easily oxidized during the high temperature heat treatment in the manufacturing process, and therefore it is necessary to perform the heat treatment entirely in a reducing atmosphere. Then, in order to prevent the reduction of the dielectric material, it is necessary to stabilize the oxygen partial pressure during the heat treatment with high accuracy.
However, during the heat treatment, the oxygen partial pressure of the object itself varies in the degreasing process and the binder removal process, so it is difficult to stabilize the oxygen partial pressure with high precision during mass production, and it is extremely difficult to put into practical use. There are difficulties and cost increases. Therefore, Ag that can be fired in air is used for the internal electrodes.
It is preferable to use a metal mainly composed of

However, the dielectric material combined with the conductor containing Ag as a main component is required to be densely sinterable at a temperature at which Ag does not melt, and the melting point of Ag is about 960 ° C.
Therefore, the selection range of the dielectric material is narrowed. Moreover, in order to obtain a high Q value at a relatively low frequency within the range of 100 MHz to 2 GHz, the dielectric material needs to have low loss. Also, the temperature coefficient of capacitance is almost determined by the dielectric material, and is 30 ppm / ° C in the capacitance region of the conventional multilayer capacitor using titanate-based materials.
The following is preferable, but it is necessary to prevent the temperature coefficient of capacity from increasing during low temperature sintering. Furthermore, when a dielectric capacitor and a conductor paste are simultaneously fired to manufacture a multilayer capacitor, structural defects such as delamination and cracks are likely to occur, so it is also necessary to suppress their occurrence. Furthermore, it is known that Ag easily causes migration, and in particular, when exposed to a high temperature and high electric field for a long time, Ag of the internal electrode layer moves to cause insulation failure. The internal electrode layer of the capacitor is exposed to a remarkably higher electric field than the internal conductor of the multilayer wiring board, which is a serious problem.

[0011]

The main object of the present invention is to:
It is an object of the present invention to provide a multilayer capacitor exhibiting a high Q value when used in a high frequency region of 100 MHz or more, particularly about 100 MHz to 2 GHz, and another object is to make such a multilayer capacitor long under high temperature and high electric field. It is to suppress the occurrence of insulation failure when exposed to time, and yet another object is to provide such a multilayer capacitor at low cost.

[0012]

This and other objects are achieved by any of the following constitutions (1) to (8). (1) A multilayer capacitor having a capacitor chip in which a dielectric layer and an internal electrode layer are stacked, wherein the dielectric layer contains a glass composite material composed of oxide aggregate and glass, and the internal electrode layer is Ag. Containing a conductor mainly composed of and glass,
In the internal electrode layer, the ratio of the glass to the total of the conductor and the glass is 5 to 20% by weight, and the multilayer capacitor. (2) The multilayer capacitor according to (1) above, which is used under an electric field of 4 V / μm or more at 60 to 200 ° C. (3) glass contained in the internal electrode layers, SiO _2: 55 to 75 mol%, Al ₂ O _3: 10 to 30 mol%, of one or more alkaline earth metal oxides: 10 to 30 mol%, ZrO ₂ : The multilayer capacitor according to (1) or (2) above, containing 0 to 5 mol%. (4) The multilayer capacitor according to any one of (1) to (3) above, which contains an oxide aggregate having a positive temperature coefficient τε of dielectric constant and an oxide aggregate having a negative τε. (5) The oxide aggregate having a positive τε is one or more kinds of aluminum oxide and magnesium titanate, and the oxide aggregate having a negative τε is one or more kinds of calcium titanate, strontium titanate and titanium oxide. The multilayer capacitor according to (4) above. (6) glass contained in the dielectric layer, SiO _2: 50-70 mol%, Al ₂ O _3: 5 to 20 mol%, of one or more alkaline earth metal oxides: 25 to 45 mol%, B ₂ O ₃ : The multilayer capacitor according to any one of (1) to (5) above, which contains 0 to 10 mol%. (7) The above (1), wherein the dielectric constant of the dielectric layer is 6 to 15.
~ The multilayer capacitor of any one of (6). (8) A method for manufacturing the multilayer capacitor according to any one of (1) to (7) above, which includes a dielectric paste layer containing oxide aggregate powder and glass powder, a conductor powder and glass powder. When firing the laminate with the conductor paste layer, 85
A method of manufacturing a multilayer capacitor, wherein the time at which the temperature is 0 ° C. or higher is set to 3 to 30 minutes.

[0013]

In the present invention, the dielectric paste is made of a glass composite material composed of oxide aggregate powder and glass powder, and the conductor paste is made of a mixture of Ag-based conductor powder and glass powder. Manufacture multilayer capacitors.

A laminated capacitor manufactured by firing a laminated body of these pastes has a conductor of an internal electrode layer mainly made of Ag having a small specific resistance, and therefore, it is 100 MHz or more, especially 1 MHz.
High Q is shown in the high frequency range of about 00MHz to 2GHz. Further, since the conductor mainly containing Ag is used, the conductor can be fired in the air, and it is not necessary to control the atmosphere with high precision, so that the manufacturing cost is low. High temperature (60-200 ℃
・ Ag migration when exposed to a high electric field (4 V / μm or more, especially 10 V / μm or more) can be drastically reduced by setting the time at which 850 ° C. or more during firing is within a predetermined range. You can

The glass powder contained in the conductor paste has the effect of bringing the sintering mode of the conductor paste layer closer to the sintering mode of the dielectric paste layer, so that delamination and cracking can be prevented. Further, the glass powder in the conductor paste layer also has an effect of preventing migration of Ag during firing and suppressing deterioration of insulation resistance of the dielectric layer.

Japanese Patent Laid-Open No. 5-211006 describes a resonator using a glass composite material as a substrate and Ag as an internal conductor. However, since the electric field applied to the internal conductor of the resonator is significantly lower than the electric field applied to the multilayer capacitor, Ag migration does not pose a problem, and in fact, the publication does not consider the prevention of Ag migration. .

[0017]

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

The laminated capacitor of the present invention has a capacitor chip which is a laminated body of a dielectric layer and an internal electrode layer.
The dielectric layer contains a glass composite material composed of an oxide aggregate and glass, and the internal electrode layer contains a conductor mainly containing Ag and glass.

The capacitor chip is manufactured by firing a laminate of a dielectric paste layer containing oxide aggregate powder and glass powder and a conductor paste layer containing conductor powder and glass powder.

In the internal electrode layer, the ratio of glass to the total of the conductor and glass is 5 to 20% by weight, preferably 7 to 10% by weight. When the proportion of glass is low, delamination is likely to occur between the internal electrode layer and the dielectric layer during firing, and Ag is likely to diffuse during firing, so that the insulation resistance is likely to deteriorate. On the other hand, when the ratio of glass is high, the resistivity of the internal electrode layers is increased and the Q value at high frequencies is significantly reduced, so that the effect of the present invention cannot be realized.

The conductor mainly composed of Ag is Ag or Ag.
Is an alloy mainly composed of Ag-Pd, A
g-Pt, Ag-Pd-Pt and the like are preferable. In order to obtain high Q at high frequency, a conductor containing 90% by weight or more of Ag is preferable, and Ag alone is particularly preferable. The average particle size of the conductor powder used in the conductor paste is not particularly limited, but is usually 1
Approximately 4 μm. If the average particle size of the conductor powder is too large, it becomes difficult to form the conductor paste layer by screen printing, transfer method or the like. On the other hand, if the average particle size of the conductor powder is too small, the dispersibility deteriorates, making it difficult to increase the content of the conductor powder in the conductor paste, and increasing the content increases the paste viscosity, and It becomes difficult to form the paste layer. The shape of the particles forming the conductor powder is not particularly limited, but it is generally preferable that the shape is spherical. However, some or all of the conductor particles may be scale-shaped.

The glass powder used in the conductor paste is preferably 700 to 1100 ° C., more preferably 800 to 9 ° C.
It is desirable to have a softening point in the range of 80 ° C. By using such a glass powder, it is possible to raise the sintering start temperature of the conductor powder, and the shrinkage behavior of the internal electrode layer and the dielectric layer can be made substantially the same. As a result, it is possible to prevent delamination and cracking of the multilayer capacitor.

The composition of the glass powder used for the conductor paste is not particularly limited and may be appropriately selected from compositions having a desired softening point. Specifically, for example, SiO ₂ : 55 to 75 mol%, Al ₂ It is preferable to select from a composition range containing O ₃ : 10 to 30 mol%, one or more alkaline earth metal oxides: 10 to 30 mol%, and ZrO ₂ : 0 to 5 mol%. In this case, as the alkaline earth metal oxide, SrO, CaO
And 1 to 3 types of MgO are preferable. The average particle size of the glass powder is not particularly limited, but usually 0.5 to 3.0 μm
Use something of a degree.

The conductor paste contains a vehicle in addition to conductor powder and glass powder. The vehicle includes a binder and a solvent. As a binder, ethyl cellulose,
Examples thereof include 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 vehicle content in the paste is preferably about 10 to 20% by weight.

The dielectric paste is about 1000 ° C. or lower,
For example, it contains oxide aggregate powder and glass powder so that it can be densely sintered at a low temperature of about 800 to 1000 ° C. As the oxide aggregate, it is preferable to use an oxide aggregate having a positive dielectric constant temperature coefficient τε and an oxide aggregate having a negative τε.

Examples of oxide aggregates having a positive τε include magnesium titanate (MgTiO ₃ ), aluminum oxide (Al ₂ O ₃ ), R ₂ Ti ₂ O ₇ (R is one or more lanthanoid elements), Ca ₂ Nb ₂ O ₇ , SrZrO _{3 and the} like can be mentioned. These may be used alone or in combination of two or more kinds, but from the viewpoint that they do not easily react with glass during firing, MgTiO ₃ , Al ₂ O ₃ , R ₂ Ti ₂ O
One or more of ₇ and SrZrO ₃ , especially MgTiO ₃ and / or Al ₂ O ₃ are preferred.

Examples of the oxide aggregate having a negative τε are calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), titanium oxide (TiO ₂ ), and S.
nO ₂ · TiO ₂ , ZrTiO ₄ , Ba ₂ Ti ₉ O ₂₀ ,
Sr ₂ Nb ₂ O ₇ , SrSnO _{3 and the} like can be mentioned. These may be used alone or in combination of two or more, but from the viewpoint that they are difficult to react with glass during firing, etc.
One or more of TiO ₃ , SrTiO ₃ and TiO ₂ are preferable.

There is no particular limitation on the mixing ratio of the oxide aggregate having a positive τε and the oxide aggregate having a negative τε.
It may be appropriately determined according to ε, τε of glass, the content ratio of the oxide aggregate and glass, and the like so that τε of the dielectric layer approaches a desired value.

Specifically, Al ₂ O _{3 is} used as the oxide aggregate.
In order to reduce the absolute value of τε when (τε> 0) and TiO ₂ (τε <0) are used, T in the oxide aggregate is reduced.
The ratio of iO ₂ is preferably 40 to 60% by weight.

As the oxide aggregate, MgTiO ₃ and / or Al ₂ O ₃ (both τε> 0) and CaTi are used.
In order to reduce the absolute value of τε when O ₃ (τε <0) is used, the ratio of CaTiO ₃ in the oxide aggregate is preferably 40 to 60% by weight.

As oxide aggregates, MgTiO ₃ and / or Al ₂ O ₃ (both τε> 0) and SrTi are used.
In order to reduce the absolute value of τε when O ₃ (τε <0) is used, the ratio of SrTiO ₃ in the oxide aggregate is preferably 40 to 60% by weight.

As the oxide aggregate, MgTiO ₃ (τ
τε when ε> 0) and TiO ₂ (τε <0) are used
In order to reduce the absolute value of
The ratio of ₂ is preferably 40 to 60% by weight.

By properly selecting and combining the oxide aggregates in this manner, the absolute value of τε of the dielectric layer can be reduced, and as a result, the absolute value of the temperature coefficient of capacitance can be reduced. . Further, since the dielectric layer containing these oxide aggregates has a high dielectric breakdown voltage, it is suitable for a capacitor having a high bias voltage. In addition, a sufficient Q value can be obtained by combining the dielectric layer containing these oxide aggregates and the internal electrode containing the conductor mainly composed of Ag.

The oxide aggregate may have a composition that is slightly deviated from the stoichiometric composition, or may be a mixture with a deviated composition or a mixture with deviated compositions.

The average particle size of the oxide aggregate powder is not particularly limited, but is preferably about 0.5 to 3 μm. If the average particle size is small, it becomes difficult to form a sheet, and if the average particle size is large, the strength of the dielectric layer becomes insufficient.

Since the dielectric paste is required to be able to be densely sintered at about 1000 ° C. or lower, the softening point of the glass powder used for the dielectric paste is preferably 700 to 900 ° C. 1000 when the softening point exceeds 900 ° C
Sintering at temperatures below ℃ becomes difficult and the softening point is 700 ℃
If it is less than the above range, it becomes difficult to remove the binder, which causes a problem in insulation.

The composition of the glass powder used for the dielectric paste is not particularly limited, but it is difficult to crystallize, the above softening point is easily obtained, and a high-strength dielectric layer can be obtained at a firing temperature of 1000 ° C. or lower. in terms such as, SiO _2: 50-70 mol%, Al ₂ O _3: 5 to 20 mol%, of one or more alkaline earth metal oxides: 25 to 45 mol%, B ₂ O _3: 0 Compositions containing mol% are preferred.

As the alkaline earth metal oxide in this case, it is preferable to use one or more of SrO, CaO and MgO, particularly the above-mentioned three types in combination, and in the case of using three types in combination,
The SrO content is preferably 15 to 30 mol%, the CaO content is 1 to 8 mol%, and the MgO content is preferably 1 to 7 mol%.

The average particle size of the glass powder is not particularly limited, but in consideration of moldability and the like, a glass powder having a particle size of about 1 to 2.5 μm is usually used.

In the dielectric layer, the content of the glass with respect to the oxide aggregate and the whole glass is preferably 50 to 80% by weight, particularly preferably 60 to 75% by weight. If it is too small, the sinterability deteriorates, and if it is too large, the dielectric strength of the dielectric layer decreases.

The relative dielectric constant of the dielectric layer containing the above oxide aggregate and glass is usually about 6 to 15 at 100 MHz to 2 GHz.

The dielectric paste is prepared by adding a vehicle to the oxide aggregate powder and the glass powder. As the vehicle, those mentioned in the explanation of the conductor paste may be used. The addition amount of the vehicle is preferably about 65 to 85 parts by weight based on 100 parts by weight of the total amount of the oxide aggregate powder and the glass powder.

The dielectric paste and the conductor paste are laminated by a printing method or a sheet method, degreased and debindered, and then fired, and further, a terminal electrode is provided so that the dielectric layer and the internal electrode layer alternate. To be a laminated capacitor. The maximum temperature during firing is preferably a temperature at which the conductor does not melt, and is usually 950 ° C or lower. Then, the baking is performed such that the time of 850 ° C. or higher is preferably 3 to 30 minutes, more preferably 7 to 15 minutes. If this time is short, densification becomes insufficient, and if this time is long, crystallization of the glass in the dielectric layer becomes remarkable,
In any case, insulation failure is likely to occur due to Ag migration under high temperature and high electric field.

In the multilayer capacitor of the present invention, the dielectric layer 1
The thickness of each layer is 100 μm or less, further 30 to 70
Even if the thickness is as thin as μm, it is possible to effectively suppress insulation failure due to migration of Ag. The number of laminated dielectric layers is usually about 3 to 10.

[0045]

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

<Conductor Paste> Ag powder (purity 99.9% or more) consisting of spherical particles having an average particle diameter of 3.0 μm and glass powder were dispersed in a vehicle by a raking machine. A vehicle was further added to the obtained mixture, and the mixture was kneaded with a three-roll to give a conductor paste. The vehicle used acrylic resin as a binder and terpineol as a solvent.

The mixing ratio of each component was as follows: Ag powder + glass powder 90% by weight, organic binder 2.5% by weight, organic solvent 7.5% by weight. Glass powder addition rate {Glass powder / (Ag powder +
Glass powder)} (wt%) are shown in Table 1. The glass powder has an average particle diameter of 2.0 μm, a softening point of 890 ° C., SiO ₂ : 66.0 mol%, Al ₂ O ₃ : 16.0 mol%, SrO: 15.0 mol%, ZrO ₂ : The one used was 3.0 mol%.

<Dielectric Paste> 62.7 parts by weight of glass powder, 21.0 parts by weight of Al ₂ O ₃ powder, and 16.3 parts by weight of TiO ₂ powder were placed in pure water in a ball mill using zirconia balls. It was crushed and mixed in the inside for 24 hours.
The average particle size after pulverization was about 0.8 μm. After crushing
73 parts by weight of vehicle was added and mixed by a ball mill for 24 hours to obtain a dielectric paste. The vehicle used acrylic resin as a binder, ethyl alcohol and toluene as a solvent, and phthalic acid ester as a plasticizer. The composition of the glass powder was: SiO ₂ : 62 mol%, Al ₂ O ₃ : 8 mol%, SrO: 20 mol%, CaO: 4 mol%, MgO: 3 mol%, B ₂ O ₃ : 3 mol%, The softening point of the glass powder was 815 ° C.

The relative permittivity ε _r of the dielectric layer at a frequency of 500 MHz and 20 ° C. was 10.7.

<Multilayer Capacitor> The dielectric paste was made into a sheet through a coater, and the conductor paste was printed on this sheet. After printing, the sheets were stacked, pressed by a hot press, and then cut to obtain a green chip. After degreasing the green chips at 120 ° C. and 250 ° C. for 2 hours and then debinding at 600 ° C. for 1 hour,
The temperature was rapidly raised, and the temperature was maintained at 900 ° C. for firing, and then the temperature was rapidly lowered. The firing was performed in air. Between 850 ° C. and 900 ° C., the temperature was raised and lowered for 1 minute or less. Table 1 shows the time when the temperature was 850 ° C. or higher during firing.
Shown in. After firing, the end surface of the chip was barrel-polished to form Ag terminal electrodes, and a Ni plating layer and a Sn plating layer were further formed on the surface of the terminal electrodes to obtain a multilayer capacitor sample. The thickness of the dielectric layer of each sample is about 50 μm,
The number of laminated dielectric layers was 5, and the capacitance was 5 pF.

For each sample, the Q value at 500 MHz was measured. For each sample, 200 ℃, 2
A dielectric breakdown test was performed under an acceleration condition of 00 V (electric field strength 4 V / μm). The time until the insulation resistance became 10 ¹⁰ Ω · cm or less was defined as the dielectric breakdown time. The dielectric breakdown test was conducted for a maximum of 24 hours. Further, after the dielectric breakdown test, each sample was cut and the cross section was polished, and the state of Ag migration and the state of delamination at the interface between the dielectric layer and the internal electrode layer were examined by an optical microscope. The results are shown in Table 1. A cross-sectional photograph of Sample No. 29 after the dielectric breakdown test is shown in FIG.

[0052]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear. That is, when the glass ratio {glass / (Ag + glass)} of the internal electrode layers is less than 5% by weight, delamination becomes remarkable, and when it exceeds 20% by weight, the Q value becomes significantly worse.

If the time at which the temperature is 850 ° C. or higher during firing is less than 3 minutes, the dielectric layer will not be densified, so that dielectric breakdown is likely to occur due to migration of Ag into the dielectric layer. There is. In Table 1, A
“Yes” or “slightly” migration of g
As shown in FIG. 1, the ones marked with are those in which bleeding of the internal electrode layer (plus electrode) due to migration of Ag was observed by optical microscope observation after the dielectric breakdown test. Even if no change was observed by an optical microscope, Ag migrasson was generated as can be seen from the results of the dielectric breakdown test. On the other hand, 850 during firing
It can be seen that even if the time at which the temperature is higher than or equal to 30 ° C. exceeds 30 minutes, dielectric breakdown easily occurs due to migration of Ag.

Further, from Table 1, a sufficiently high Q value was obtained when the time at which the temperature was 850 ° C. or higher during firing was 7 minutes or longer, while the effect of Ag migration was observed when the time was 15 minutes or shorter. I know there isn't. Sample No. 9 had a low temperature coefficient of capacity of +10 ppm / ° C.

The X-ray diffraction chart of the dielectric layer of sample No. 9 is shown in FIG. 2, and the X-ray diffraction chart of the dielectric layer of sample No. 29 is shown in FIG. Also, sample No. 9 and 2
Scanning electron micrographs of the cross section of the dielectric layer of Sample No. 9 are shown in FIGS. 4 (a) and 4 (b), respectively. Note that these have not been subjected to a dielectric breakdown test. Sample No. where the temperature was 850 ° C or higher during firing for a short time
In Fig. 9 (Fig. 2), a halo that is considered to be derived from the amorphous glass is remarkably observed. On the other hand, in sample No. 29 (FIG. 3) where the temperature was 850 ° C. or higher for a long time, there were peaks (marked with “x”) which were not observed in FIG. It can be seen that the glass inside is crystallized. Actually, sample No. 2 in FIG.
In the glass of No. 9, needle-like crystal phase precipitation, which was not observed in FIG. 4 (a), was observed.

From the results of the above examples, the effect of the present invention is clear.

[Brief description of drawings]

FIG. 1 is a drawing-substitute photograph showing a metallographic structure, which is an optical microscope photograph of a cross section of a multilayer capacitor (Sample No. 29 in Table 1) for showing a state of Ag migration in an internal electrode layer.

FIG. 2 is an X-ray diffraction chart of sample No. 9 in Table 1.

FIG. 3 is an X-ray diffraction chart of sample No. 29 in Table 1.

FIG. 4 is a drawing-substitute photograph showing a crystal structure,
(A) is a scanning electron micrograph of sample No. 9 cross section of Table 1, and (b) is a scanning electron micrograph of sample No. 29 cross section of Table 1.

Claims (8)

[Claims] 1. A multilayer capacitor having a capacitor chip in which a dielectric layer and an internal electrode layer are stacked, wherein the dielectric layer contains a glass composite material composed of oxide aggregate and glass, and the internal electrode layer. Contains a conductor mainly composed of Ag and glass, and the ratio of glass to the total of the conductor and glass in the internal electrode layer is 5 to 20% by weight. 2. The multilayer capacitor according to claim 1, which is used under an electric field of 4 V / μm or more at 60 to 200 ° C. 3. The glass contained in the internal electrode layer comprises: SiO ₂ : 55 to 75 mol%, Al ₂ O ₃ : 10 to 30 mol%, and one or more alkaline earth metal oxides: 10 to 30 mol%. , ZrO _2: according to claim 1 or 2 of the multilayer capacitor containing 0-5 mol%. 4. The multilayer capacitor according to claim 1, which contains an oxide aggregate having a positive dielectric constant temperature coefficient τε and an oxide aggregate having a negative τε. 5. The oxide aggregate having a positive τε is at least one of aluminum oxide and magnesium titanate, and τ
The multilayer capacitor according to claim 4, wherein the oxide aggregate having a negative ε is one or more of calcium titanate, strontium titanate, and titanium oxide. 6. The glass contained in the dielectric layer comprises: SiO ₂ : 50 to 70 mol%, Al ₂ O ₃ : 5 to 20 mol%, one or more alkaline earth metal oxides: 25 to 45 mol%. , B ₂ O _3: one of the multilayer capacitor of claims 1 to 5 containing 0 to 10 mol%. 7. The multilayer capacitor according to claim 1, wherein the dielectric constant of the dielectric layer is 6 to 15. 8. A method for manufacturing a multilayer capacitor according to claim 1, wherein a dielectric paste layer containing oxide aggregate powder and glass powder, and a conductor containing conductor powder and glass powder. When firing the laminate with the paste layer, the time of 850 ° C. or higher is 3 to
A method for manufacturing a multilayer capacitor, which comprises setting the time for 30 minutes.