JPH088189B2 - Method for manufacturing laminated porcelain capacitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminated ceramic capacitor capable of increasing the capacity.

[0002]

2. Description of the Related Art A surface reoxidation type semiconductor ceramic capacitor is known as one type of semiconductor ceramic capacitors. When manufacturing this surface reoxidation type semiconductor ceramic capacitor, for example, a main component composed of BaTiO ₃ (barium titanate) is used, and a rare earth element (La, C) as a valence control material is added.
e, Pr, Nd, Sm, Y, etc.), a Mn compound, and CaZrO ₃ are added to form a molded body of the porcelain material composition. To obtain a porcelain sintered body. next,
102 in a reducing atmosphere consisting of hydrogen and nitrogen
Heat treatment is performed at 0 to 1100 ° C. to change into a semiconductor porcelain.
Then, the semiconductor porcelain was exposed to the atmosphere (oxidizing atmosphere) at 1000
A heat treatment (reoxidation treatment) at 10 to 40 ° C. is performed to form a dielectric ceramic layer (film) made of an oxide layer on the surface of the semiconductor ceramic. Then, a pair of electrodes is formed by applying a silver paste on the dielectric ceramic layer and baking it.

In this surface reoxidation type semiconductor ceramic capacitor, the semiconductor ceramic layer functions as an electrode of the capacitor, and the extremely thin dielectric ceramic layer of about 10 to 20 μm between the semiconductor ceramic layer and the electrode is the dielectric layer of the capacitor. Work as. Therefore, the equivalent (apparent) relative dielectric constant is increased, and the capacity can be increased.

In the above description, since the pair of electrodes is made of silver, two dielectric porcelain layers are interposed between the pair of electrodes, and two capacitors are equivalently connected in series. As a result,
Large capacity is hindered. To solve this problem, a part of the dielectric porcelain is removed to expose the semiconductor porcelain layer, and one of the electrodes may be brought into ohmic contact therewith. Further, one electrode material may be a base metal such as Zn, and the base metal may reduce the dielectric porcelain layer when baking the electrode to form ohmic contact with the semiconductor porcelain layer to form the electrode.

[0005]

In spite of various attempts to increase the capacity as described above, the surface reoxidation type semiconductor ceramic capacitor cannot be laminated, so that it can be further miniaturized. And it was impossible to increase the capacity.

Therefore, an object of the present invention is to provide a method capable of easily manufacturing a surface-reoxidation type laminated ceramic capacitor which can be miniaturized and have a large capacity.

[0007]

[Means for Solving the Problems] To achieve the above object
The method of manufacturing a laminated ceramic capacitor according to
Palladium (P
Conductive paste containing d) and base metal is formed into a predetermined pattern.
Applying the conductive layer to form a conductive layer.
A step of laminating a plurality of the above-mentioned sheets to obtain a laminated body,
Palladium turns into palladium oxide, and then
With a temperature rising process in which dium returns to palladium again
And firing the laminated body in an oxidizing atmosphere.

A laminated magnet made according to the present invention is used.
Capacitor was formed by oxidation with semiconductor porcelain layer
Since it has a dielectric ceramic layer, that is, an oxide layer, it is a surface reoxidized type.
It can be called a laminated porcelain capacitor.

[0009]

In the present invention, palladium (Pd) is 56
Palladium oxide (P
dO), and when the temperature is further raised to about 820 ° C, oxidation occurs.
Indium (Pd) functions as a reducing agent near 560 ° C,
It functions as an oxidant near 820 ° C. On the other hand, base metals
Converted to oxide in low temperature range of 200-700 ℃
And functions as a reducing agent. Then base metal oxides
Diffuses into the porcelain layer and functions as a sintering aid. Para
Due to the depletion of oxygen from porcelain materials by sulphur and base metals
The porcelain material has been reduced by the
Be converted. After that, palladium oxide (PdO) releases oxygen.
By giving the semiconductor porcelain layer,
The area in contact with the electrode is oxidized and this is the dielectric.
It becomes a body porcelain layer (film).

Laminated porcelain capacitor made by the method of the present invention
Between the two internal electrode layers of the sensor
Since the body porcelain layer is arranged, the entire area between the two inner electrode layers is
Part does not function as the dielectric layer of the capacitor,
The layer functions as the dielectric of the capacitor, and the semiconductor porcelain layer is
Functions as an electrode. Dielectric porcelain layer is about 10 ~ 20μm
Since it is extremely thin, the static electricity between the two internal electrode layers
The capacity becomes extremely large.

[0011]

[Embodiment 1] Next, a laminated ceramic capacitor according to an embodiment of the present invention and a method of manufacturing the same will be described with reference to FIGS.

FIG. 1 shows in principle the novel laminated ceramic capacitor. This porcelain capacitor is composed of a rectangular porcelain substrate 3 including first and second electrode layers 1 and 2 as internal electrodes, and a pair of external electrodes 4 and 5. One external electrode 4 provided on one side surface of the porcelain substrate 3 is connected to the first electrode layer 1, and the other external electrode 5 provided on the other side surface is connected to the second electrode layer 2. There is.

The porcelain substrate 3 has first and second dielectric porcelain layers 6 and 7 which are in contact with the electrode layers 1 and 2, and a first porcelain substrate 3 which is disposed between the dielectric porcelain layers 6 and 7. Semiconductor porcelain layer, first electrode layer 1, second semiconductor porcelain layer 9 formed on the upper side of first electrode layer 1, and fourth semiconductor layer formed on the lower side of second electrode layer 2.
The semiconductor porcelain layer 10 and the dielectric porcelain layer 11 in the surface region of the porcelain base body 3.

The laminated ceramic capacitor having the structure shown in FIG. 1 was manufactured as follows. First, BaTiO ₃ (barium titanate) 94.5 mol% and La ₂ O ₃ (lanthanum oxide) were added to La.
To 2.0 mol%, CeO ₂ (cerium oxide) to Ce of 1.0 mol%, Nd ₂ O ₃ (neodymium oxide) to Nd of 1.0 mol%, CaZrO ₃ A ceramic raw material powder containing 1.0 mol% of (calcium zirconate) and 0.5 mol% of MnO ₂ (manganese oxide) converted to Mn was prepared.

Next, an organic binder and a plasticizer were added to the raw material composition to form a slurry, and a 25 μm green sheet (unsintered sheet) was obtained by the doctor blade method.

Next, from 100 parts by weight of Pd (palladium) powder having an average particle size of about 0.2 μm, 10 parts by weight of spherical Zn powder having an average particle size of about 1.0 μm as a base metal, and an appropriate amount of an organic binder. Was prepared. Next, this conductive paste was printed in a predetermined pattern on the green sheet and dried to obtain a conductive layer. The printed thickness of the conductive paste is about 2.5 μm. Further, a plurality of green sheets having a conductive layer based on a conductive paste were prepared, and a plurality of reinforcing green sheets having no conductive layer were also prepared.

Next, as shown in principle in FIG. 2, a first green sheet 8a having a first conductive layer 1a, a second green sheet 10a having a second conductive layer 2a, and upper and lower reinforcements. Sheets 11a and 11b were superposed and pressed to obtain a molded body 12.

Next, the molded body 12 of FIG. 2 is heated in an N ₂ atmosphere (neutral atmosphere) at 350 ° C. for 2 hours, and the green sheets 8a, 10a, 11a, 11b and the conductive layers 1a, 2a are heated.
The organic binder inside was discharged. Next, in the air atmosphere (oxidizing atmosphere), the heating temperature of the molded body 12 is set to 1 per hour.
The temperature was raised to 1300 ° C. at a rate of 50 ° C., the temperature was maintained at 1300 ° C. for 2 hours, and the compact 20 was fired to obtain a sintered body.

During this firing, the molded body 12 was heated to 560 ° C.
When heated to a high temperature, the first and second conductive layers 1a, 2a
Pd contained in P removes oxygen from the oxide in the porcelain material, reduces the porcelain material, and Pd becomes PdO. At the same time, Zn also removes oxygen from the oxide in the porcelain material, reduces the porcelain material, and becomes ZnO. Furthermore, the firing temperature is 820
When it reaches around ℃, PdO functions as an oxidant,
Oxygen of PdO is deprived of the porcelain material, returns to Pd, and becomes the first and second electrode layers 1 and 2 shown in FIG. Oxygen separated from PdO oxidizes the regions adjacent to the electrode layers 1 and 2 to form the dielectric ceramic layers 7 and 8 having a thickness of about 3 μm shown in FIG. Zn becomes ZnO at 200 to 700 ° C., and then
It diffuses in the compact and functions as a sintering aid.

The capacitance C (p
F), dielectric loss tan δ (%) and dielectric breakdown voltage Vbd (volt) were measured. As a result, C was 9500 pF, tan δ was 2.5%, and Vbd was 300 volts. Note that C and
The tan δ was measured under the conditions of a measurement voltage of 0.1 V and a measurement frequency of 1 kHz. Further, Vbd was measured by a DC boost breakdown method.

[0021]

[Comparative Example] In order to investigate the effect of a base metal such as Zn added to the conductive paste, the first and second electrode layers 1, based on the conductive paste containing no base metal in the conductive paste,
A laminated porcelain capacitor was manufactured in the same manner as in Example 1 except that No. 2 was formed, and C, tan δ,
When Vbd was measured, it was 3300 pF, 1.5%, 110
It was 0V.

The electrostatic capacitance C of Example 1 is 9500 pF, whereas the electrostatic capacitance C of Comparative Example is 3300 pF, and the electrostatic capacitance C of Example 1 is significantly high. The reason why C becomes high in this way is that not only the dielectric layer is provided between the first electrode layer 1 and the second electrode layer 2, but also the first dielectric porcelain layer 6, the semiconductor porcelain layer 8, the second This is because it is composed of the dielectric porcelain layer 7. That is, the semiconductor porcelain layer 8 acts as the electrode of the capacitor, and only the extremely thin first and second dielectric porcelain layers 6 and 7 act as the dielectric layer of the capacitor.

[0023]

Example 2 In order to investigate the change in the characteristics of the capacitor due to the change in the proportion of Zn as a base metal in the conductive paste for forming the first and second electrode layers 1 and 2, 100
5 parts by weight of Zn, 20 parts by weight, and 4 parts by weight of Pd.
A capacitor was manufactured in the same manner as in Example 1 except that the levels were changed to 0, 50, and 60 parts by weight, and the characteristics were measured. The following results were obtained.

Zn 5 parts by weight C 6200 pF tan δ 2.0% Vbd 600 V Zn 20 parts by weight C 9500 pF tan δ 2.5% Vbd 300 V Zn 40 parts by weight C 6900 pF tan δ 4.5% Vbd 200V Zn 50 parts by weight C 4300pF tan δ 7.5% Vbd 100V Zn 60 parts by weight C 3000pF tan δ 10.0% Vbd 70V

As is clear from this result, Zn is 50
The capacitance C of the capacitor in the range of parts by weight or less is larger than C of the capacitor of the comparative example in which the first and second electrode layers 1 and 2 are formed with Pd paste containing no Zn. On the other hand, when Zn is 60 parts by weight, C is smaller than that of the comparative example in which Zn is zero. Therefore, the ratio of 100 parts by weight of the base metal to Pd in the conductive paste is preferably 50 parts by weight or less.

If the proportion of the base metal (Zn) becomes too large, the proportion of Pd in the conductive paste will decrease, and PdO as an oxidant for forming the dielectric ceramic layers 6 and 7 of FIG. The dielectric ceramic layers 6 and 7 are thinned and the breakdown voltage Vbd is lowered. In addition, the electrode layers 1, 2
Oxide (ZnO) of the base metal (Zn) remains in the inside, and the denseness of the electrode layers 1 and 2 decreases, and eventually the capacitance decreases and ta
An increase in n δ occurs.

[0027]

Example 3 In order to confirm that copper (Cu) can be used instead of Zn as the base metal of the conductive paste for forming the electrode layers 1 and 2, 100 parts by weight of Pd is used.
On the other hand, a capacitor was prepared in the same manner as in Example 1 except that a conductive paste containing 5, 20, and 50 parts by weight of Cu was used, and the characteristics were measured. The following results were obtained. Cu 5 parts by weight C 7000pF tan δ 2.5% Vbd 450V Cu 20 parts by weight C 11000pF tan δ 4.5% Vbd 250V Cu 50 parts by weight C 4000pF tan δ 11.0% Vbd 70V

[0028]

Example 4 In order to confirm that nickel (Ni) can be used as a base metal of the conductive paste for forming the electrode layers 1 and 2, Ni of 5, 20, 50 parts by weight is added to 100 parts by weight of Pd. A capacitor was produced in the same manner as in Example 1 except that the conductive paste added in the same manner as the parts was used, and the characteristics were measured. The following results were obtained. Ni 5 parts by weight C 8000pF tan δ 2.5% Vbd 450V Ni 20 parts by weight C 11000pF tan δ 3.5% Vbd 250V Ni 50 parts by weight C 4000pF tan δ 11.0% Vbd 70V

[0029]

[Embodiment 5] To confirm that aluminum (Al) can be used as the base metal of the conductive paste for forming the electrode layers 1 and 2, 5, 20, 50 parts by weight of Al are added to 100 parts by weight of Pd. A capacitor was produced in the same manner as in Example 1 except that the conductive paste added in the same manner as the parts was used, and the characteristics were measured. The following results were obtained. Al 5 parts by weight C 8000pF tan δ 3.0% Vbd 450V Al 20 parts by weight C 10000pF tan δ 5.5% Vbd 350V Al 50 parts by weight C 4300pF tan δ 11.0% Vbd 70V

[0030]

Example 6 In order to confirm that multiple kinds of metals can be used as the base metal of the conductive paste for forming the electrode layers 1 and 2, Z is added to 100 parts by weight of Pd.
Two kinds of capacitors were prepared in the same manner as in Example 1 except that the conductive paste containing n10 parts by weight and the conductive paste containing 10 parts by weight of Cu and 10 parts by weight of Ni were used, and the characteristics were measured. Results were obtained. Zn 10 parts by weight, Al 10 parts by weight C 11000pF tan δ 4.5% Vbd 300V Cu 10 parts by weight, Ni 10 parts by weight C 8000pF tan δ 2.5% Vbd 500V

[0031]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible.

For the manufacture of the capacitors according to the invention, it is possible to use all the porcelain materials used in known surface-reoxidation porcelain capacitors. For example, as the rare earth element, one or more kinds of La, Ce, Pr, Nd, Sm, Y and the like can be used. In addition, TiO ₂
About 1 to 10 mol% of (titanium oxide) can be added.

MnCO ₃ can be used instead of MnO ₂ . Also, instead of BaTiO ₃ , BaC
O ₃ and TiO ₂ can be used as starting materials.

The base metal mixed with Pd is about 200 to 70.
Any metal other than the metals shown in the examples, such as Sn, may be used as long as it is a metal that oxidizes at 0 ° C. Further, two kinds of base metals or various combinations other than these can be added to Pd.

It is possible to add another metal which does not inhibit the action of Pd and the base metal.

The maximum temperature during firing can be set to various temperatures below about 1400 ° C.

Although only two electrode layers 1 and 2 are provided in FIG. 1, it is needless to say that more internal electrodes can be provided as in a general multilayer capacitor.

Even if the semiconductor porcelain layer 8 is not entirely formed between the two dielectric porcelain layers 6 and 7, and the dielectric porcelain layer remains in the semiconductor porcelain layer 8, the function and effect of the present invention can be obtained. To be Also, only one of the two electrode layers 1 and 2 is Pd,
The dielectric ceramic layer can be formed on only one side.

[0039]

[Effect of the Invention] allows you to easily manufacture the surface reoxidation multilayer ceramic capacitor having a large electrostatic capacitance according to the apparent in the present invention from above.

[Brief description of drawings]

FIG. 1 is a sectional view showing in principle a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing in principle a molded body for making the ceramic capacitor of FIG.

[Explanation of symbols]

 1 electrode layer 2 〃 6 dielectric porcelain layer 7 〃 8 semiconductor porcelain layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01G 4/30 301 E 7924-5E

Claims (1)

[Claims] 1. A green sheet made of semiconductor porcelain material
Conductive paste containing palladium (Pd) and base metal
A step of applying a predetermined pattern to form a conductive layer, and stacking a plurality of the above-mentioned sheets coated with the conductive layer.
The process of obtaining the layered body and the process of converting palladium into palladium oxide
With a temperature rising process in which dium returns to palladium again
And firing the laminate in an oxidizing atmosphere.
And a method of manufacturing a laminated ceramic capacitor.