KR900005443B1 - Thick film capacitor - Google Patents

Abstract

The thick film capacitor comprises a sintered layer of a ferro- electric material, mainly consisting of one or more ferroelectric cpds. with a perovskite structure and an inorganic binder with a eutectic compsn. which produces a liquid phase at a temp. lower than a sintering temp. of the cpds. At least two electrodes are formed on both surfaces of the material. The ferro-electric cpds. include Pb(Fe1/2Nb1/2) O3-Ba(CU1/2W1/2)O3, BaTiO3 and PbTiO3. The inorganic binders include binary mixtures of oxides, e.g. PbO-CuO, PbO-WO3, BaO-WO3 etc. The binder promotes shrinkage of the inorganic cpds. o n sintering to provide a dense compsn. and good dielectric characteristic.

Description

Thick film capacitor

1 is a cross-sectional view of a thick film capacitor according to a specific embodiment of the present invention.

2 is a cross-sectional view of a state before sintering a thick film capacitor according to another specific embodiment of the present invention.

3 is a cross-sectional view of a thick film capacitor according to another specific embodiment of the present invention.

4 and 5 are characteristics of the thick film capacitor according to an embodiment of the present invention and the characteristics of the conventional thick film capacitor in comparison with the effect of the aging treatment at high temperatures.

* Explanation of symbols for main parts of the drawings

1,11 substrate 2a, 2b electrode

3,3a, 3b: ferroelectric layer 4: thick film capacitor

5: tip capacitor 12a, 12b: metal paste for electrode

13a, 13b: ferroelectric paste

14 Ferroelectric Paste without Inorganic Binder

The present invention relates to a thick film capacitor.

In general, a thick film capacitor has a structure in which a ferroelectric sintered layer is interposed between metal electrodes, and the ferroelectric compound used in the thick film capacitor deteriorates sintering property, so that the ferroelectric compound alone is very difficult to form a sintered layer.

For this reason, in a conventional thick film capacitor, crystalline or amorphous glass was added as a binder and sintered to form a ferroelectric sintered layer.

However, when glass is added, the dielectric properties of the ferroelectric sintered layer are greatly worsened.

For example, when commercially available crystalline or amorphous glass is added to a ferroelectric inorganic compound having a dielectric constant of 20000, the dielectric constant of the resulting ferroelectric sintered layer is significantly reduced to 1 / 20-1 / 200 of the pre-sintering value at 100-1000.

This is because the addition of glass breaks the perovskite structure of the ferroelectric inorganic compound upon sintering.

Conventional thick film capacitors contain glass in the ferroelectric sintered layer and thus have poor moisture resistance.

In conventional capacitors, electrode metals easily move and migration resistance is poor.

An object of the present invention is to provide a thick film capacitor having good sinterability, high dielectric constant, good moisture resistance, and which can effectively prevent movement of electrode metals.

In order to achieve the object of the present invention, the thick-film capacitor is composed of the following: (a) having a process composition which becomes liquid at the sintering temperature below the ferroelectric inorganic compound having a perovskite structure and the ferroelectric inorganic compound A ferroelectric sintered layer composed mainly of an inorganic binder, and (b) at least two electrodes formed on both sides of the ferroelectric sintered layer.

Since the binder contained in the ferroelectric sintered layer acts as a binder at a temperature at which the perovskite structure of the ferroelectric inorganic compound is not destroyed, the ferroelectric compound in the sintered layer can maintain the original perovskite structure.

As a result, it is possible to obtain high sintering properties, good dielectric properties and high moisture resistance. Examples of ferroelectric inorganic compounds constituting the ferroelectric sintered layer in the thick film capacitor of the present invention include those shown in Table 1 below.

Of these compounds, the following compounds are particularly preferred: Pb (Fe _1/2 Nb _2/2 ) O ₃ -Ba (Cu _1/2 W _1/2 ) O ₃ , BaTiO, PbTiO, and (Pb, X) { (Zn _1/3 Nb _2/3 ) (Mg _1/3 Nb _2/3 ) Ti} O ₃ ; X = Ba, Ca, Sr, La

TABLE 1

Examples of the inorganic binder included in the ferroelectric sintered layer in the present invention include a binary mixture of the following oxides: PbO-CuO, PbO-WO ₃ , PbO-Nb ₂ O ₅ , PbO-Fe ₂ O ₃ , PbO -ZnO, PbO-TiO ₂ , PbO-CaO, PbO-Sb ₂ O ₃ , BaO-WO ₃ , Nb ₂ O ₃ -TiO ₂ , TiO ₂ -MgO, PbO-MgO, etc. Also contain 3 or more oxides Mixtures can be used.

In addition, compounds which are converted into the above-mentioned oxides during sintering, such as oxides, halides, or organometallic compounds, can be used as the inorganic binder of the present invention.

The inorganic binder becomes a liquid at or below the sintering temperature of the ferroelectric inorganic compound of the perovskite structure, and has a process composition that becomes liquid even beyond a wide composition range.

Therefore, the inorganic binder can promote the sintering of the ferroelectric inorganic compound without changing the perovskite structure of the compound.

The inorganic binder of the present invention promotes shrinkage of the ferroelectric inorganic compound during sintering to have a dense composition and stabilizes sintering.

Therefore, in the present invention, the ferroelectric sintered layer has the same excellent dielectric properties as the inorganic compound itself, and has high moisture resistance and mobility resistance.

The inorganic binder composed of the aforementioned compounds can be added directly to the ferroelectric inorganic compound after mixing the respective components.

If necessary, the binder may be added after presintering is performed.

In the present invention, the pair of electrodes is formed by printing and sintering a metal paste selected from the group consisting of Au, Ag, Ag-Pd, Pt, Ag-Pt, Cu, Ni, Pd, W and the like.

In a preferred specific embodiment of the present invention, one of the pair of electrodes 2a is formed on an insulating substrate 1 such as an alumina substrate, and the ferroelectric sintered layer 3 and the other electrode 2b having the above-described composition are formed. In turn, it is formed thereon as shown in FIG.

As shown in FIG. 3, a predetermined amount of the above-mentioned inorganic binder is added to the ferroelectric sintered layer 3a, and is interposed between the insulating substrate 1 and the electrode 2a.

In this structure, the adhesion strength between the electrode 2a and the board | substrate 1 can be improved compared with the structure of the electrode 2a formed directly on the board | substrate 1.

The manufacturing method of the thick film capacitor of the present invention is as follows.

First, a ferroelectric inorganic compound as shown in Table 1 is made.

For this purpose, the raw materials are weighed to prepare a composition corresponding to each ferroelectric inorganic compound, and then presintered or the like to synthesize a ferroelectric inorganic compound.

The inorganic compound does not always need to contain 100% perovskite phase.

The components of the inorganic binder of the present invention are weighed to obtain the desired process composition, and the composition is mixed with the ferroelectric inorganic compound described above.

In this case, the mixing ratio of the ferroelectric inorganic compound and the inorganic binder is different and cannot be uniformly limited.

In general, when the amount of the binder is too large, the dielectric properties of the sintered layer are lowered. On the other hand, when the amount of the binder is too small, sufficient sinterability cannot be obtained.

Therefore, the mixing ratio should be determined to obtain similar dielectric properties and high sinterability.

The obtained mixture is ground to a predetermined particle size and a solvent and an inorganic binder are added to form a ferroelectric paste.

If the average particle size of the pulverized mixture is 1.0 µm or less, crystal grains are less likely to grow at the time of sintering, resulting in lowering of the dielectric constant.

If the average particle size exceeds 10 mu m, printing of the ferroelectric paste is disturbed.

Therefore, it is preferable to set the average particle size to 1.0 to 10 mu m.

As a solvent for making the ferroelectric paste, a solvent such as terpineol, methylethyl cellosolve, n-butanol, or the like may be generally used.

As the organic binder, a binder for ceramic molding such as ethyl cellulose, methyl cellulose, polyacrylic resin, polystyrene, polyurethane, polyvinyl alcohol, polyvinyl butyral, nitrocellulose, or the like can be generally used.

The metal paste and the ferroelectric paste described above are alternately printed on the insulating substrate and stacked in the order of the metal paste layer, the ferroelectric paste layer, and the other metal paste layer.

Then, the obtained multilayer structure is sintered.

In this way, a thick film capacitor 4 having a ferroelectric sintered layer 3 as shown in FIG. 1, and metal electrodes 2a and 2b below and below can be formed.

The sintering temperature at this time varies depending on the metal paste and ferroelectric paste used.

In general, the sintering temperature should be within the range that other resistors, wirings, etc. do not swell or peel off.

The above paste layers are sintered simultaneously.

However, printing and sintering may be repeated to form the layers 2a, 3, 2b one after the other.

When manufacturing a thick film capacitor according to the above-described method, if the inorganic binder is liquid, the performance as a binder is improved.

After sintering, at the grain boundaries of the ferroelectric inorganic compound, the inorganic binder forms a bonding layer or diffuses into the crystal lattice of the ferroelectric inorganic compound.

However, when the inorganic binder of the present invention is diffused into the crystal lattice of the ferroelectric inorganic compound, unlike the glass used in the conventional method, the inorganic binder does not destroy the perovskite structure of the ferroelectric compound.

As a result, the above-described method can obtain good dielectric properties, high moisture resistance and mobility resistance.

Another manufacturing method is as follows.

In this specific example, a second ferroelectric paste having the same composition as the above-described ferroelectric paste is produced except that no inorganic binder is added.

Using the second ferroelectric paste, the above-described ferroelectric paste and metal paste, the metal paste layer 12a, the ferroelectric paste layer 13a, the second ferroelectric paste layer 14, and the ferroelectric paste as shown in FIG. The layer 13b and the metal paste layer 12b are printed and stacked in order.

When the structure is sintered in the state shown in FIG. 2, the paste layers 12a, 13a, 14, 13b and 12b are sintered and the inorganic binder contained in the layers 13a and 13b is the second ferroelectric. It diffuses into the paste layer 14.

For this reason, even if the second ferroelectric paste layer 14 does not originally contain an inorganic binder, a good sintered state can be obtained by diffusion of the inorganic binder during sintering.

In addition, the obtained second sintered layer has less inorganic binder than the upper and lower sintered layers and thus has good dielectric properties.

Therefore, in this specific embodiment, since the second ferroelectric sintered layer is included, a thick film capacitor having dielectric properties superior to that shown in FIG. 1 can be obtained.

In this specific embodiment, the sintering process may be performed before the next paste layer is stacked to separate and sinter each paste layer 12a, 13a, 14, 13b, and 12b.

Another specific embodiment will be described with reference to FIG. 3.

In this specific embodiment, a ferroelectric paste layer, a metal paste layer, a ferroelectric paste layer, and another metal paste layer are printed and stacked on the insulating substrate 1 in order.

The resulting structure is then sintered and cut to the desired size.

Next, a tip capacitor 5 in which ferroelectric sintered layers 3a and 3b and electrodes 2a and 2b are alternately stacked may be manufactured as shown in FIG. 3.

As described above, the ferroelectric layer 3a serves to improve the mechanical adhesion between the insulating substrate 1 and the electrode 2a.

The tip capacitor shown in FIG. 3 is composed of two electrode layers 2a and 2b and two ferroelectric layers 3a and 3b, and the tip capacitor having a larger number of electrodes and ferroelectric layers stacked in a similar manner. It can manufacture.

Instead of sintering the electrodes 2a and 2b and the ferroelectric layers 3a and 3b at the same time, they may be printed and sintered in order.

The method of manufacturing the tip capacitor according to the above has the following advantages over the capacitor manufactured by the green sheet method.

If the green sheet method is used, a special tool is required to support the multilayer sheet.

However, in the above specific embodiment, since the insulating substrate 1 has a supporting function, no special tool is required, so that the number of processes can be reduced.

In addition, a thick-film belt-furnace can be used for degreasing and sintering, and the production can be completed in a short time.

In the manufacturing method of this invention, it is preferable to age the obtained sintered compact at high temperature.

In the present invention, aging at a high temperature can improve dielectric properties such as dielectric constant, dielectric loss ratio (tan δ 10 ^-2 ), volume resistivity, and the like.

This is clearly different from the fact that aging at high temperatures degrades dielectric properties in conventional thick film capacitors using glass binders.

This means that the glass breaks the perovskite structure of the ferroelectric sintered layer during aging at high temperatures, whereas the inorganic binders described above in the present invention not only damage the perovskite structure of the ferroelectric sintered layer, but also inhibit crystal growth. Promote

In order to achieve this effect, the upper limit temperature value of the aging should be set within the range where voids, swelling, dissolution, etc. do not occur in the ferroelectric layer and the electrode. It should be set to

The embodiments of the present invention are described as follows.

[Example 1-16]

(A) Synthesis of Ferroelectric Inorganic Compound

Using PbO, Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , BaCO ₃ , CuO, MgCO ₃ and NiO as starting materials, the ferroelectric compounds shown in Table 1 were weighed to obtain compositions corresponding to PFN and BCW.

The PFN and BCW compositions and additives NiO, MgO and MnO were basis weighted in the molar ratios shown in Table 2.

Here, the mixing ratio of PFN and BCW was set such that X and Y satisfy X + Y = 1 in the following equation; X (PFN) -Y (BCW) Subsequently, these raw materials were wet mixed with a ball mill, the mixture was pre-sintered at 700-800 ° C, and the obtained sintered structure was pulverized and dried to form a ferroelectric inorganic compound.

(B) Preparation of Inorganic Binder

PbO, CuO, and WO ₃ were used as the raw materials to carry out the basis weights at the molar ratios shown in Table 2.

These raw materials were wet mixed with a ball mill and dried to obtain process compositions PbO-CuO and PbO-WO ₃ .

These process compositions were pre-sintered at 600-830 ° C.

Thereafter, the presintered composition was ground with a ball mill and dried to use as an inorganic binder.

(C) Preparation of Ferroelectric Paste

The ferroelectric inorganic compound and the inorganic binder produced according to the step (A) (B) were basis weighted at the ratios shown in Table 2.

16 types of ferroelectric pastes were prepared by adding terpineol 28 wt% as a solvent and 4 wt% ethyl-cellulose as an organic binder to 68 wt% of these raw materials.

(D) thick film capacitor manufacturing

A thick film capacitor as shown in FIG. 1 was prepared using a ferroelectric paste as follows.

The metal paste based on Ag-Pb was printed on a 2 "x 2" alumina substrate, and the above-described ferroelectric paste was printed and stacked thereon.

Again, another Ag-Pb-based metal paste was printed and stacked on the ferroelectric paste layer of the structure.

The resulting structure was sintered at 900 ° C. for 10 minutes using a belt oven.

The dielectric film and dielectric loss factor (tanδ × 10 ⁻² ) of the obtained thick film capacitor were measured at 1 KHz.

The obtained results are shown in Table 2.

For comparison, a conventional thick film capacitor using glass as an inorganic binder was produced in the same manner as described above. (Comparative Example 1-5)

The results of these comparative examples are also shown in Table 2.

TABLE 2

As can be seen from the results shown in Table 2, the conventional thick film capacitors of Comparative Examples 1-5 had a low dielectric constant of 12-270, while the thick film capacitors of Examples 1-16 had a very high dielectric constant of 4000-15000.

The thick film capacitors obtained in Examples 2-9 and Comparative Example 3 were subjected to aging five times at a high temperature of 900 ° C. for 10 minutes.

The dielectric constant was measured at each end of the aging process to test the change in dielectric constant due to aging at high temperatures. The results shown in FIG. 4 were obtained.

The thick film capacitors obtained in Example 13 and Comparative Example 3 were subjected to aging six times at a high temperature of 600 ° C. for 10 minutes. At the end of each aging process, the volume resistivity was measured to test the volume resistivity due to aging at high temperatures. The results shown in FIG. 5 were obtained.

As can be seen from the results shown in FIGS. 4 and 5, in the thick film capacitors of the embodiments, aging at high temperature can increase the dielectric constant by 10% and increase the volume resistivity by 100 times.

In contrast to this, in the thick film capacitors of the comparative examples, aging at high temperature causes both the dielectric constant and the volume resistivity to deteriorate. In aging at high temperatures, no degradation in the thick film capacitors of the examples was observed.

[Example 17-47]

(A) Synthesis of ferroelectric inorganic compound.

PbO, Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , BaCO ₃ CuO, MgCO ₃ , MnCO ₃ , NiO, SrCO ₃ , CaCO ₃ , ZrO ₂ , CO ₂ O ₃ , ZnO, TiO ₂ , Sb ₂ O ₃ and using Ta ₂ O ₅ had a basis weight so as to obtain a composition corresponding to the ferroelectric compounds shown in Table 3 and Table 4. Abbreviations such as PBZMT in Tables 3 and 4 refer to the ferroelectric inorganic compounds in Table 1. The composition corresponding to the ferroelectric inorganic compound and the additive MnO were basis weighted in the molar ratios of Tables 3 and 4. At this time, when using a plurality of raw materials corresponding to the ferroelectric inorganic compound, the sum of their molar ratios was set to one.

These raw materials were wet mixed with a ball mill, presintered at 700-800 ° C., and then crushed and dried with a ball mill to form a ferroelectric inorganic compound.

(B) Preparation of an inorganic binder.

PbO, CuO, WO ₃ , Nb ₂ O ₃ , Sb ₂ O ₃ , BaO, Fe ₂ O ₃ , ZnO and CaO were used as the starting materials, and the basis weights were shown in Tables 3 and 4. The raw materials were wet-mixed with a ball mill and dried to prepare the process compositions PbO-CuO, PbO-WO ₃ , PbO-Nb ₂ O ₃ , PbO-Sb ₂ O ₃ , PbO-CaO, PbO-Fe ₂ O ₃ , PbO-ZnO And BaO-WO ₃ were obtained. These process compositions were presintered at 700-830 ° C., ground in a ball mill and dried to form inorganic binders.

(C) Preparation of Ferroelectric Paste.

The ferroelectric inorganic compound and the inorganic binder prepared in step (A) and (B) were basis weighted at the ratios shown in Tables 3 and 4. Thirty kinds of ferroelectric pastes were prepared by adding 28 wt% of terpineol as a solvent and 4 wt% of ethyl-cellulose as an organic binder to 68 wt% of these raw materials.

(D) Fabrication of thick film capacitors.

In the same manner as in Example 1-16, the thick film capacitor shown in FIG. 1 was manufactured using the above-described ferroelectric paste.

In Examples 21-23, however, the ferroelectric paste was printed and sintered as a buffer layer between the alumina substrate and the metal electrode. The dielectric constant and dielectric loss factor (tan δ × 10 ⁻² ) of the obtained thick film capacitor were measured at 1 KHz.

The results are shown in Tables 3 and 4. For comparison, a conventional thick film capacitor using glass as an inorganic binder was prepared in the same manner as described above. (Comparative Example 6-10). The results are shown in Table 3 and Table 4.

TABLE 3a

TABLE 3b

TABLE 4

It can be seen from the results of Table 3 and Table 4.

The conventional thick film capacitors of Comparative Examples 6-10 have a low dielectric constant of 12-2900, while the thick film capacitors of Examples 17-47 are very high as 4000-11000 in dielectric constant.

In Examples 1-46 and Comparative Examples 1-10, a resistor was formed on a single substrate together with a thick film capacitor using a commercially available resistor paste in the following two ways.

In the first method, a resistor paste layer was printed and sintered on the insulating paste layer formed on the upper metal paste layer. In the second method, a resistor paste was printed and sintered in contact with the ferroelectric paste layer adjacent to the thick film capacitor. The obtained resistors were examined.

In the case of Examples 1-46, a resistor having a desired resistance value could be formed by any method.

On the other hand, in Comparative Example 1-10, a resistor having a desired resistance value could not be formed by any method. This is because the glass contained in the ferroelectric paste as a binder in the comparative example diffuses into the resistor paste layer during sintering.

Example 48-53

(A) Synthesis of ferroelectric inorganic compound.

PbO, Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , BaCO ₃ and CuO were used as starting materials, so that the compositions corresponding to the ferroelectric compounds PFN and BCW shown in Table 1 were obtained. PFN and BCW raw materials were mixed in the molar ratio X: Y (X + Y = 1) shown in Table 5. These raw materials were then wet mixed in a ball mill and presintered at 700-800 ° C. The presintered body was ground with a ball mill and dried to produce a ferroelectric inorganic compound.

(B) Preparation of an inorganic binder.

PbO, WO ₃ , CuO, Fe ₂ O ₃ , Nb ₂ O _5, and BaO were used as the starting materials, and the basis weight was measured at the molar ratio shown in Table 5. These materials were wet mixed with a ball mill and dried to provide process compositions PbO-CuO, PbO-WO ₃ , PbO-Nb ₂ O ₅ , PbO-Nb ₂ O ₅ -BaO-CuO, PbO-Nb ₂ O ₅ -WO ₃ and PbO -WO ₃ -CuO was obtained. These process compositions were used directly as inorganic binders. In addition, the process compositions were presintered at 600-1000 ° C., ground in a ball mill and dried to use as inorganic binders.

(C) Preparation of Ferroelectric Paste.

The ferroelectric inorganic compound and the inorganic binder produced in step (A) and (B) were basis weighted at the ratios shown in Table 5. 28 wt% of terpinol as a solvent and 4 wt% of ethyl-cellulose as an organic binder were added to 68 wt% of the raw materials and mixed to prepare six types of ferroelectric pastes.

A ferroelectric paste without an inorganic binder was prepared by adding and mixing 28 wt% of terpinol as a solvent and 4 wt% of ethyl-cellulose as an organic binder to 68 wt% of a ferroelectric inorganic compound.

(D) Fabrication of thick film capacitors.

The multilayer structure shown in Table 2 was formed by a printing method using a ferroelectric paste containing an inorganic binder, a ferroelectric paste without an inorganic binder, and a metal paste based on Ag-Pb. A thick film capacitor was prepared by sintering the multilayer structure at 900 ° C. for 10 minutes using a belt furnace.

The dielectric constant and dielectric loss ratio (tan δ × 10 ⁻² ) of the obtained thick film capacitor were measured at 1 KHz, and the results are shown in Table 5.

For comparison, conventional thick film capacitors were made by using glass as the inorganic binder and omitting the ferroelectric paste layer (" 14 " in FIG. 2) without the inorganic binder. (Comparative Example 11).

In the same manner as in the above-described embodiment, a water film capacitor in which the paste layer without the inorganic binder ("14" in FIG. 2) was omitted was made. (Reference Example 1-2).

Table 5 shows the results of the comparative example and the reference example.

TABLE 5

As can be seen from the results in Table 5, the conventional thick film capacitor of Comparative Example 11 has a low dielectric constant of 50, whereas the thick film capacitors of Examples 48-53 have extremely high dielectric constant of 13000 or more.

The values of these embodiments are much greater than the dielectric constants 8000 and 9000 of Reference Examples 1-2.

This effect is due to the stacking and sintering of the ferroelectric paste ("14" in FIG. 2) without the inorganic binder.

Example 54-68

(a) Synthesis of Ferroelectric Inorganic Compound.

PbO, Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , BaCO ₃ , CuO, MgCO ₃ and NiO were used as starting materials, so that the compositions corresponding to PFN and BCW, which are ferroelectric inorganic compounds of Table 1, could be obtained. Ferroelectric inorganic compounds and additives NiO, MgO and MnO were weighed in the molar ratios shown in Table 6. Here, PFN and BCW described above are set to be X (PFN) -Y (BCW) [X + Y = 1] as can be seen from the values in Table 6.

These raw materials were wet mixed in a ball mill, presintered at 700-800 ° C., and again milled and dried in a ball mill to form a ferroelectric inorganic compound.

(B) Preparation of an inorganic binder.

PbO, CuO and WO ₃ were used as the starting materials, and the basis weights were shown in Table 6, followed by wet mixing with a ball mill and drying to obtain process compositions PbO-CuO and PbO-WO ₃ . The process composition was presintered at 600-830 ° C. and then ground in a ball mill and dried to form an inorganic binder.

(C) Preparation of Ferroelectric Paste.

The ferroelectric inorganic compound and the inorganic binder produced in Step (A) and (B) were weighed out in the molar ratios in Table 6. Fifteen kinds of ferroelectric pastes were prepared by adding 28 wt% of terpineol as a solvent and 4 wt% of ethyl-cellulose as an organic binder to 68 wt% of the raw materials.

(D) Fabrication of tip capacitors.

Ag-Pb-based metal pastes, the above-described ferroelectric pastes, and Ag-Pb-based metal pastes were printed and stacked on a 2 " x 2 " alumina substrate in order, and the resulting structure was obtained using a belt oven. Sintering was performed at 900 ° C. for 10 minutes.

Each sintered structure was cut into pieces to make a tip capacitor having the structure shown in FIG. The dielectric constant and dielectric loss ratio (tanδ × 10 ⁻² ) of the obtained thick film capacitor were measured at 1 KHz, and the results are shown in Table 6.

For comparison, conventional thick film capacitors were made using glass as the inorganic binder. (Comparative Example 12-16). A tip capacitor was manufactured by the green sheet method. (Comparative Example 17). Table 6 shows the results of these comparative examples.

TABLE 6a

TABLE 6b

As can be seen from the results in Table 6, the conventional thick film capacitors of Comparative Examples 12-16 have a low dielectric constant of 12-270, while the thick film capacitors of Examples 54-68 have a very high dielectric constant of 4000-7000.

The thickness of the tip capacitor of Comparative Example 17 is 0.6-10 mm, while the thickness of the tip capacitor of Examples 54-68 is very small, 0.5 mm or less.

Example 69-98

(A) Synthesis of ferroelectric inorganic compound.

As starting materials PbO, Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , BaCO ₃ , CuO, MgCO ₃ , NiO, SrCO ₃ , CaCO ₃ , ZrO ₂ , CO ₂ O ₃ , ZnO, TiO, Sb ₂ O ₃ And Ta ₂ O ₃ to give a composition equivalent to the ferroelectric inorganic compounds shown in Tables 7 and 8. Abbreviations such as PBZMT in Table 7 and Table 8 refer to the ferroelectric inorganic compounds of Table 1.

The ferroelectric inorganic compound and the additive MnO were weighed in the molar ratios of Tables 7 and 8. Here, when using various types of ferroelectric inorganic compounds, the total molar ratio was set to one. These raw materials were wet mixed with a ball mill, pre-sintered at 700-800 ° C., ground by ball mill and dried to form a ferroelectric inorganic compound.

(B) Preparation of an inorganic binder.

PbO, CuO, WO ₃ , Nb ₂ O ₅ , Sb ₂ O ₃ , BaO, Fe ₂ O ₃ and CaO as raw materials were weighed in a molar ratio of Tables 7 and 8, and wet-mixed with a ball mill and dried. The obtained process composition PbO-CuO, PbO-WO ₃ , PbO-Nb ₂ O ₅ , PbO-Sb ₂ O ₃ , PbO-CaO, PbO-Fe ₂ O ₃ , PbO-ZnO and BaO-WO ₃ as direct inorganic binders Used.

In addition, these process compositions were presintered at 700-830 ° C., then pulverized with a ball mill and dried to be used as inorganic binders.

(C) Preparation of Ferroelectric Paste.

The ferroelectric inorganic compound and the inorganic binder produced in step (A) and (B) were basis weighted at the molar ratios shown in Tables 7 and 8. Thirty kinds of ferroelectric pastes were prepared by adding and mixing terpineol 28 wt% as a solvent and 4 wt% ethyl-cellulose as an organic binder to 68 wt% of each raw material.

(D) Fabrication of tip capacitors.

The electrode pastes of Tables 7 and 8, the ferroelectric pastes and the metal pastes obtained in step (C) were printed and stacked on a 2 "x 2" alumina substrate in order, and the structures were fabricated at 900 캜 using a belt oven. Sintered for 10 minutes.

Each sintered structure was cut into pieces to make a tip capacitor having the structure shown in FIG. The dielectric constant and dielectric loss ratio (tanδ × 10 ⁻² ) of the obtained thick film capacitor were measured at 1 KHz, and the results are shown in Tables 7 and 8.

For comparison, conventional thick film capacitors were made using glass as the inorganic binder. (Comparative Example 18-22). The results are shown in Tables 7 and 8.

TABLE 7a

TABLE 7b

TABLE 8

As can be seen from the results of Tables 7 and 8, the conventional thick film capacitors of Comparative Examples 18-22 have low dielectric constants of 50-2900, while the thick film capacitors of Examples 69-98 have extremely high dielectric constants of 4000-11000. .

As described with reference to Comparative Example 17, the thickness of the tip capacitor formed by the green sheet method is 0.6-10 mm, whereas the thickness of the tip capacitor of Examples 69-98 is very small, 0.5 mm or less.

As described above, the thick film capacitor of the present invention has high sintering property, good dielectric properties, high moisture resistance and high mobility.

In addition, the thick film capacitor of the present invention can be miniaturized and thinned, is advantageous for packaging, and can reduce the number of processes.

Claims (14)

A ferroelectric sintered layer of an inorganic binder having a process composition which becomes a liquid at a sintering temperature below the sintering temperature of the ferroelectric inorganic compound having a perovskite structure and the ferroelectric inorganic compound, and at least two electrodes are provided on both sides of the ferroelectric sintered layer. Thick film capacitors. The thick film capacitor according to claim 1, wherein an inorganic binder is present at grain boundaries of the ferroelectric inorganic compound in the ferroelectric sintered layer. 2. The thick film capacitor according to claim 1, wherein the inorganic binder diffuses into the crystal of the inorganic compound in the ferroelectric sintered layer. The thick film capacitor according to claim 1, wherein the inorganic binder is present in grain boundaries and crystals of the ferroelectric inorganic compound in the ferroelectric sintered layer. The ferroelectric inorganic compounds of claim 1, wherein the ferroelectric inorganic compounds are selected from Pb (Fe _1/2 Nb _2/3 ) O ₃ -Ba (Cu _1/2 W _1/2 ) O ₃ , BaTiO ₃ , PbTiO ₃ and (Pb, Ba) { And (Zn _1/3 Nb _2/3 ) (Mg _1/3 Nb _2/3 ) Ti} O ₃ . The method of claim 1, wherein the inorganic binder is PbO-CuO, PbO-WO ₃ , PbO-Nb ₂ O ₅ , PbO-Fe ₂ O ₃ , PbO-ZnO, PbO-TiO ₂ , PbO-CaO, PbO-Sb ₂ O ₃ , BaO-WO ₃ , Nb ₂ O ₃ -TiO ₂ , TiO-MgO and PbO-MgO, a thick film capacitor, characterized in that it is selected from the group of composition. 7. The thick film capacitor of claim 6 wherein the inorganic binder is selected from the group consisting of a composition that is converted into a process composition by oxidation during sintering. The thick film capacitor according to claim 1, wherein the ferroelectric sintered layer is formed of an intermediate layer containing a small amount of an inorganic binder, and layers formed above and below the intermediate layer and containing a large amount of an inorganic binder. It is mainly composed of a first metal electrode layer formed on an insulating substrate, and an inorganic binder having a process composition which is directly stacked on the first electrode layer and has a process composition which becomes liquid below the sintering temperature of the ferroelectric inorganic compound having a perovskite structure and the ferroelectric inorganic compounds. And a ferroelectric sintered layer, and a second metal electrode layer formed directly on the ferroelectric sintered layer. The thick film capacitor according to claim 9, further comprising a ferroelectric sintered layer interposed between the insulating substrate and the first metal electrode layer. An inorganic binder having a first metal electrode layer formed on an insulating substrate, a ferroelectric inorganic compound having a perovskite structure, and a process composition which becomes a liquid at or below the sintering temperature of the ferroelectric inorganic compound which is directly stacked on the first metal electrode layer. A thick film capacitor having a ferroelectric sintered layer mainly composed of a second metal electrode layer formed directly on the ferroelectric sintered layer, wherein the thick film capacitor is cut into a tip having a desired predetermined size. 12. The thick film capacitor according to claim 11, wherein at least one multilayer structure consisting of a ferroelectric sintered layer and a second metal electrode layer is stacked on the second metal electrode layer. The thick film capacitor according to claim 11, further comprising a ferroelectric sintered layer interposed between the insulating substrate and the first metal electrode layer. A thick film capacitor obtained by aging the thick film capacitor according to claim 1 produced by the thick film method at a high temperature.

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