JPH09134845A - Manufacture of single-plate ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method by which a highly reliable single- plate ceramic capacitor can be manufactured inexpensively. SOLUTION: In a method for manufacturing single-plate ceramic capacitor, a composition containing the powder of a raw material for forming molded body is put in a metallic mold 10 or rubber mold in which partition walls for forming splitting grooves are formed and compression-molded. Then a dielectric plate is manufactured by degreasing and baking the molded body and electrodes are formed on the dielectric plate so that the electrodes cannot contain the splitting grooves formed on the surface of the dielectric plate. After forming the electrodes, the dielectric plate is split into pieces. A single-plate ceramic capacitor is manufactured through the above-mentioned processes.

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 single plate ceramic capacitor, and more particularly to a method for manufacturing a single plate ceramic capacitor used for adjustment in an electronic circuit such as a mobile radio communication device.

[0002]

2. Description of the Related Art Capacitors are classified into paper, mica, ceramics, electrolyte, glass and other special ones according to the type of dielectric used. Among these, ceramic (porcelain) capacitors are used as parts of various electronic devices because they have excellent durability and high reliability. The porcelain capacitors are classified into temperature compensating porcelain capacitors, high-permittivity porcelain capacitors, semiconductor porcelain capacitors, etc. according to the temperature characteristics of their capacities, and are classified into single-plate porcelain capacitors and laminated porcelain capacitors according to their shapes.

In the above classification, the single-plate porcelain capacitor is usually one in which one layer (one sheet) of dielectric porcelain is formed and electrodes are formed on both sides of the dielectric porcelain, and it is relatively easy to manufacture. It has the feature that it can. The single plate capacitor has various uses, and as one of the uses,
Applications for high frequencies that do not require high accuracy of capacitance,
For example, there is an application for adjustment in an electronic circuit such as a mobile wireless communication device.

The single plate porcelain capacitor for the above purpose is manufactured by the following method. First, raw material powders are blended so as to have a composition of a dielectric ceramic that constitutes a single-plate ceramic capacitor after firing, and powder of the dielectric ceramic composition is synthesized by calcination, and a binder and the like are added to and mixed with this powder. rear,
Granulate using a spray dryer or the like to produce granulated powder. The composition of the dielectric porcelain constituting the single plate porcelain capacitor is not particularly limited, but has a relative permittivity of several tens or more and a Q value of 3,000 to in a high frequency band, particularly in a frequency band of GHz band. It is preferably as large as about 50,000. Next, a metal mold, a rubber mold, or the like is filled with this granulated powder, and uniaxial pressure molding or hydrostatic molding is performed to produce a plate-shaped molded body. Next, this plate-shaped molded body is put into a firing furnace, and a degreasing step of decomposing and eliminating organic substances is performed, and then firing is performed at 1300 to 1400 ° C. to produce a dielectric plate.

In order to obtain a capacitor, it is necessary to form electrodes on both main surfaces of the obtained dielectric plate, and examples of methods for forming the electrodes include a plating method and a printing method. . Usually, Ag or Cu is used as the electrode material, but when plating is performed, the dielectric plate is immersed in a plating bath for forming the Ag or Cu plating film, and the Ag plating film or Cu plating film is formed on the entire surface. Form. On the other hand, when the electrodes are formed by printing, a conductor paste containing Ag powder or Cu powder is printed on both sides of the dielectric plate, or pattern printing is performed on both sides of the dielectric plate, and then 800 to 900. The printed pattern is printed on the dielectric plate by heating at a temperature of about ℃.

[0006] The single plate ceramic capacitor is manufactured by cutting the dielectric plate (hereinafter also referred to as an undivided ceramic capacitor) manufactured in this way and having electrodes formed on both main surfaces into a predetermined size. Is completed.

[0007]

However, when the single plate ceramic capacitor is manufactured by the above method, there are the following problems.

That is, when cutting the undivided porcelain capacitor, the electrodes may be turned over, which may cause a problem in the reliability of the obtained single plate porcelain capacitor.

Further, in order to prevent the electrode from being turned over, when the pattern is printed on both main surfaces by reversing the cut portion, there is no mark on both main surfaces of the dielectric plate, and therefore the printed pattern is There was a problem that a gap might occur.

Further, in order to divide the undivided porcelain capacitor into individual single-plate porcelain capacitors, it is necessary to cut them by using an expensive cutting machine or the like, which makes the cutting expensive and the manufacturing cost high. There were challenges.

As a result of the above problems,
There was also a problem that the yield was lowered and the manufacturing cost was high.

The present invention has been made in view of the above problems, and it is possible to easily form a printed pattern without deviation on both principal surfaces, and to provide a large-area dielectric in which electrodes are formed on both principal surfaces. It is possible to provide a method for manufacturing a single-plate ceramic capacitor, which can inexpensively manufacture a highly reliable single-plate ceramic capacitor because the body plate can be easily divided and the electrodes are not turned over. Has an aim.

[0013]

Means for Solving the Problems and Effects Thereof A method for manufacturing a single-plate ceramic capacitor according to the present invention is a mold or rubber in which a composition for forming a raw material powder for forming a molded body is formed with partition walls for forming dividing grooves. A molding step of filling the mold and compression-molding, a dielectric plate manufacturing step of manufacturing a dielectric plate by degreasing and firing the molding, and dividing grooves formed in the dielectric plate. It is characterized by including an electrode forming step of forming an electrode so as not to include it and a dividing step of dividing the dielectric plate (undivided ceramic capacitor) on which the electrode is formed.

According to the above-described method for manufacturing a single-plate ceramic capacitor, the dividing grooves are formed in advance on both main surfaces of the undivided ceramic capacitor, and the electrode pattern can be formed with reference to the grooves. There is no risk that the front and back print patterns will be misaligned. Further, the undivided porcelain capacitor can be easily divided by utilizing the dividing groove,
Furthermore, since electrodes are not formed in the dividing grooves even during division, the electrodes are not turned over, and a highly reliable single plate ceramic capacitor can be manufactured at low cost.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a single plate ceramic capacitor according to an embodiment of the present invention will be described below. First, a granulated product containing a raw material powder having a dielectric ceramic composition is manufactured by a method similar to the method described in the section of the related art. The dielectric porcelain to be manufactured may be the same as the conventional one, and specific examples thereof include those having a three-component system of BaO-TiO ₂ -WO ₃ as a main component, Pb _x (Mg _1/3 Nb _2/3 ) O _3-y (In _1/2 Nb _1/2 ) O ₃ (however, x = 0.
5 to 0.9, y = 0.1 to 0.5), Pb _x Zr _(1-x) O _(2-x) (However, 0.
42 ≦ x ≦ 0.69) Nd ₂ O ₃ and Gd ₂ O ₃
Nd ₂ O ₃ , Gd ₂ O ₃ ,
And Bi ₂ O ₃ added.

Next, in the step of producing a molded body, a granulated product containing the raw material powder of the dielectric ceramic composition is a mold or a rubber mold (hereinafter referred to as a mold etc.) in which partition walls for forming dividing grooves are formed. And then compression molded.

FIG. 1 (a) is a bottom view schematically showing an upper mold used in a molded body manufacturing process of the method for manufacturing a single plate ceramic capacitor according to the embodiment, and FIG. 1 (b) is a lower mold. It is a top view which showed the type | mold typically, (c) is a longitudinal cross-sectional view which showed typically the type | mold comprised by the said upper mold and the said lower mold.

Four partition walls 13a, 13 for forming dividing grooves are formed on the inner surface of each of the upper mold 11 and the lower mold 12 constituting the mold 10 in the vertical and horizontal directions.
b is formed, and the partition walls 13a and 13b divide the inside of the mold 10 into the shapes of individual molded ceramic capacitors.

At the time of producing the molded body, the side wall 1 of the lower mold 12
The part surrounded by 4 is filled with the granulated powder, and the upper mold 11
A molded body is produced by covering and pressing. Normal,
Since the length of one side of the molded body shrinks by 10 to 20% by sintering, the length of one side after sintering is 3 to 4 in consideration of the shrinkage.
The widths D ₁ and D ₂ between the partition walls 13a and 13b are set to be mm.
Set. Moreover, since the thickness also shrinks by 10 to 20%, the thickness after shrinkage should be about 0.6 to 2 mm.
Adjust the amount of granulated powder to fill. In addition, the partition wall 13a,
The height H of 13b is set to be about 1/5 to 2/5 of the thickness of the obtained single plate ceramic capacitor. If it is less than ⅕ of the thickness of the single-plate ceramic capacitor, it becomes difficult to divide it, while if it exceeds 2/5 of the thickness of the single-plate ceramic capacitor, it becomes easy to break before the dividing step, which makes it difficult to handle.

The cross-sectional shape of the partition walls 13a, 13b is not particularly limited, but a V-shaped tip having an acute angle may be used. However, the sharp angle portion is easily worn away after many uses. Considering this, the partitions 13a and 1 as shown
It is preferable that the portion 3b has a rectangular sectional shape or a trapezoidal sectional shape. Partition walls 13a, 13b
When the cross-sectional shape of is rectangular, its width d is 0.5 to 1.0 m
m is preferred. Further, the pressure at the time of performing compression molding is preferably 800 to 1200 kg / cm ² as in the conventional case.

Next, as a dielectric plate manufacturing step, a dielectric plate (dielectric porcelain) is manufactured by degreasing and firing the molded body manufactured in the above steps. The manufacturing conditions in the manufacturing process of this dielectric plate may be the same as those in the conventional case. For example, degreasing is performed at 300 to 500 ° C. in an oxidizing atmosphere to decompose and remove organic substances, and then 1300 in the same oxidizing atmosphere. Firing is performed at ˜1400 ° C. to manufacture a dielectric plate. Through this step, the dielectric plate having the dividing grooves is manufactured. The depth of the divided groove formed is 0.2 to 0.6.
mm, and the width thereof is 0.4 to 0.8 mm (when the cross-sectional shape is a trapezoid, the width of the widest portion).

Next, as an electrode forming step, electrodes are formed on both main surfaces of the dielectric plate so as not to include the dividing grooves formed in the dielectric plate.

The electrodes are usually formed by thick film printing, but the electrodes may be formed by plating. First, the case of performing thick film printing will be described. The conductor paste used for thick film printing may be a conductor paste containing Ag powder or Cu powder that has been conventionally used, and the printing method may be a conventionally used method such as screen printing. be able to.

For example, 84 to 96% by weight of Cu powder having an average particle size of about 5 to 10 μm, 2 to 6% by weight of a binder such as an acrylic resin, and 2 to 2% of a solvent such as terpineol.
The conductor paste containing 16% by weight is printed by screen printing, but the conductor paste is not printed on the portion where the dividing groove is formed and its periphery. At this time, considering the collapse around the groove portion of the molded body when forming the dividing groove and the printing error at the time of printing, 100 to 200 μm is larger than the dividing groove.
It is preferable to provide a portion in which the conductor paste is not printed with a width of about m. The print pattern may have a circular shape or an elliptical shape, but a rectangular shape is preferable from the viewpoint that a large electrode area can be obtained.

After performing the thick film printing of the Ag paste or the Cu paste on both main surfaces of the dielectric plate in this manner, 800 to 9
By heat treatment at about 00 ° C., an electrode made of Ag or Cu is formed on the surface of the dielectric plate.

Finally, solder is plated on the electrodes made of Ag or Cu to complete the production of the single plate ceramic capacitor.

Next, a method of forming a plating film on both main surfaces of the dielectric plate will be described. In this case, first, by screen printing or the like, a resin or the like is applied to the dividing groove in which the electrode is not formed and its periphery and dried. Next, the dielectric plate is immersed in a plating bath, and the dielectric plate is subjected to an electroless plating treatment to form a plating film only on a necessary portion. In addition, in order to form a plating film having excellent adhesion, the dielectric plate was immersed in advance in an acidic solution containing stannous chloride and palladium chloride to precipitate palladium as a precipitation nucleus on the surface of the dielectric plate. You can leave it. The resin applied to the dividing groove and its periphery is removed by immersing it in a solvent or the like to dissolve it after the plating treatment. A resin for forming a photoresist may be used as the coating resin.

Next, as a dividing step, a bending stress is applied to the undivided ceramic capacitors having electrodes formed on both main surfaces by a mechanical method or a manual work to divide the undivided ceramic capacitors. The undivided porcelain capacitor can also be easily divided by hand.

When the undivided porcelain capacitor is mechanically divided by using a dividing device, it is similar to the dividing device for a ceramic substrate disclosed in, for example, Japanese Utility Model Laid-Open No. 3-8 and Japanese Unexamined Patent Publication No. 6-120367. By using the device for manufacturing a single-plate porcelain capacitor having a size smaller than that of the ceramic substrate, it is possible to automatically divide the undivided porcelain capacitor.

[0030]

[Examples and Comparative Examples] Hereinafter, a method for manufacturing a single-plate ceramic capacitor according to Examples will be described. The conditions of the method for manufacturing the single plate ceramic capacitor according to the example are as follows. (i) Molded body manufacturing process Composition of dielectric ceramic composition to be manufactured BaO: 18.1 mol% TiO ₂ : 81.4 mol% WO ₃ : 0.5 mol% MnO: 0.1 mol% Baking temperature: 1000 ° C. Uniaxial molding pressure by the mold 10 used: 1000 kg / cm ² Mold size: 60 mm × 60 mm × 2 mm Cross-sectional shape of the dividing groove formed on the surface of the mold: rectangular (0.7 mm × 0.7 mm) ) (Ii) Dielectric plate manufacturing process Degreasing condition Atmosphere: Atmosphere temperature: 400 ° C Time: 2 hours Firing condition Atmosphere: Atmosphere atmosphere Temperature: 1350 ° C Time: 2 hours (iii) Electrode forming process (using Cu conductor paste) Screen printing) Baking atmosphere: Nitrogen atmosphere Temperature: 900 ° C. Time: 10 minutes Cu layer thickness: 10 μm Electrode-unformed part: Dividing groove and range of 200 μm width from dividing groove Dielectric plate Shape of sintered body) Shape of dividing groove Rectangle: 0.55 mm x 0.55 mm Dimensions of dielectric plate: 48 mm x 48 mm x 1.6 mm Characteristics of dielectric plate Relative permittivity: 39.5 Q value: 6000 Resonance frequency Temperature coefficient (τ _f ): 12 ppm / ℃ (iV) Dividing process Shape of divided single plate porcelain capacitor Shape of dielectric porcelain: 3 mm × 3 mm × 1.6 mm Capacitance of porcelain capacitor: 2 pF Manufactured by dividing Number of single plate porcelain capacitors produced: 144 Product defect rate: 0.7% In addition, as a comparative example, a metal having the same shape as that of the example except that the partition for forming the dividing groove is not formed in the mold. Using a mold, an undivided dielectric ceramic was manufactured under the same conditions as in the example, the undivided dielectric ceramic was fixed with a resin, and the blade thickness was 0.
Cutting with a 5mm dicing saw,
The same number of single-plate porcelain capacitors having the same shape as those in the example were manufactured. The product defect rate at this time was 10.4%.

As is clear from the above results, in the method for manufacturing a single plate capacitor according to this embodiment, the granulated powder for forming the compact is filled in the mold having the partition walls for forming the dividing grooves. After compression molding, a dielectric plate is manufactured by degreasing and firing the molded body, and electrodes are formed so as not to include the dividing grooves formed in the dielectric plate. Since the undivided porcelain capacitor is divided, the following effects are achieved. That is, there is no fear that the printed pattern will be displaced between the front and back of the dielectric plate, and
Since the undivided porcelain capacitor can be easily divided by using the dividing groove, and since the electrode is not formed in the dividing groove even at the time of dividing, the electrode is not turned over. , The incidence of defective products is extremely low,
It is possible to inexpensively manufacture a single plate ceramic capacitor having excellent reliability.

[Brief description of the drawings]

FIG. 1A is a bottom view schematically showing an upper mold used in a method for manufacturing a single-plate ceramic capacitor according to an embodiment of the present invention, and FIG. 1B is a lower mold schematically. FIG. 4C is a vertical cross-sectional view schematically showing a mold including the upper mold and the lower mold, and FIG.

[Explanation of symbols]

 10 mold 11 upper mold 12 lower mold 13a, 13b partition wall

Claims (1)

[Claims] 1. A molded body producing step of filling a composition or a raw material powder for forming a molded body into a mold or a rubber mold in which partition walls for forming dividing grooves are formed and compression molding, and degreasing and degreasing the molded body. A dielectric plate manufacturing step of manufacturing a dielectric plate by performing firing, an electrode forming step of forming an electrode so as not to include the dividing groove formed in the dielectric plate, and the dielectric plate having an electrode formed therein. And a dividing step of dividing a body plate.