JPH0614494B2 - Multilayer ceramic capacitor and manufacturing method thereof - Google Patents

Description

The present invention relates to a laminated ceramic capacitor and a method for manufacturing the same.

[Prior Art] A monolithic ceramic capacitor is a composite body in which ceramics and metal electrodes are integrated, and is an important element component that is indispensable for general consumer equipment as electronic components become more compact and lightweight. is there.

A conventional method for manufacturing a monolithic ceramic capacitor is as follows when the main steps are shown according to the procedure.

(1) A step of thinly applying a slurry containing a dielectric ceramic raw material powder and a binder onto a base film and drying it to form a ceramic green sheet, (2) a substantially rectangular shape to be an internal electrode on the ceramic green sheet. A step of printing a conductive paste so that a plurality of conductive films are arranged at equal intervals vertically and horizontally, (3) a plurality of these ceramic green sheets are alternately staggered in the longitudinal direction of the substantially rectangular conductive film. Stacking the sheets and crimping, (4) cutting into a plurality of elements so that the internal electrodes are not exposed on both side surfaces and alternating internal electrodes are exposed on both end surfaces, and (5) this element After baking, the conductive film is applied to both exposed end surfaces of the internal electrode and baked to form an external electrode connected to the internal electrode.

The monolithic ceramic capacitor thus obtained is
A plurality of internal electrodes are formed inside the ceramic laminate,
External electrodes are formed on both end surfaces of the ceramic laminate. One end of each internal electrode is connected to the external electrode, and the other end does not reach the end face of the ceramic laminate, leaving an end margin.

An end margin is formed between the end of the internal electrode that is not connected to the external electrode and the end face of the laminated body, and a side margin is formed at a fixed distance from both end faces of the ceramic laminated body to the edges of the internal electrode.

Therefore, when the normal process as described above is taken, an error in the printing process, an error in the sheet stacking process,
Also, various errors such as an error in cutting the laminated body must be taken into consideration. Therefore, in order to secure a predetermined margin, it is necessary to allow a margin to the extent that the error can be allowed. There is no choice but to make it smaller, and it is not possible to expect high efficiency in obtaining electrostatic capacitance, especially for small monolithic ceramic capacitors.

As a means for solving such a problem, for example, as disclosed in Japanese Patent Publication No. 53-23496, the side margin is eliminated, the internal electrode is exposed on the side surface of the ceramic laminate, and then the side surface is glazed. A coating method has been proposed.

[Problems to be Solved by the Invention] The monolithic ceramic capacitor obtained by the glaze coating method has a different thermal expansion coefficient and the like because the glaze is made of glass, which is a material different from ceramics. There is a problem that it is weak against the like, and since glass is melted and adhered to the ceramic, it cannot be applied thickly, and it is impossible to form a ceramic laminate having a columnar shape or a polygonal columnar shape.

An object of the present invention is to solve the above problems and to form a product having an arbitrary outer shape, and to manufacture a product having a small variation in capacitance without considering an error in a conductive film printing process or the like. It is to provide a manufacturing method of.

[Means and Actions for Solving the Problems] As a result of research aimed at achieving the above object, the present inventors have found that a ceramic kneaded clay having the same quality as the ceramic laminated body with a stick-shaped ceramic laminated body (laminated body block) as a core is used. It was found that if the extrusion molding is performed so as to cover the side surface of the laminated body, the above-mentioned problems can be solved, and further, if the shape of the nozzle is selected during the extrusion molding, a molded body having any desired outer shape can be obtained. Has reached the present invention.

That is, the laminated ceramic capacitor of the present invention can be described as follows.

On the upper surface of the rectangular ceramic dielectric sheet, a unit sheet for lamination, which has an end margin only at one end in the longitudinal direction and has a conductive film for the internal electrode layer without taking a side margin, A stick-shaped laminated body having a rectangular cross section, which is made by laminating a plurality of sheets so that the parts are aligned and the end margins are alternately on the opposite side, is arranged in the central portion as a core body, and the ceramics of the previous period is arranged around the core body. An outer peripheral body made of a fired material of ceramic kneaded clay of the same quality as the ceramic of the derivative sheet is formed integrally with the core body so as to surround the entire side surface of the core body with a predetermined outer shape, and the outer peripheral body serves as a side margin. An insulating skin, and a structure in which end portions without end margins of the internal electrodes are connected to external electrodes formed on both end faces in the longitudinal direction of the laminated body. La ceramic capacitor.

The method for manufacturing the laminated ceramic capacitor of the present invention can be described as follows.

(A) A plurality of unit sheet sheets in which conductive films of a constant length to be internal electrodes are formed on the upper surface of a thin and long ceramic green sheet of a constant width at regular intervals in the longitudinal direction without side margins. The sheets are superposed on each other by shifting their positions so that the center lines of the conductive films of the constant length and the center lines of the conductive film interval portions in the similar unit sheets that are adjacent to each other are in the same vertical plane. A laminated body block in which internal electrodes are exposed on the side surface is prepared in an integrated form; on the other hand, (b) having a hopper-shaped ceramic kneaded clay storage container, at the lower discharge end of the container, A first nozzle for pushing out a ceramic kneaded clay having a cross section of an arbitrary shape slightly larger than the cross section of the laminated body block, and an end surface of the first nozzle that is inside the first nozzle and slightly inside the end surface of the first nozzle. A second nozzle which is disposed and which is directly connected to the crosshead disposed in the central portion of the ceramic kneaded material storage container and constitutes the outlet thereof, and further applies a pressure to the ceramic kneaded material of the container A molding machine having a pressing means for extruding the kneaded material from one nozzle is prepared; (C) The first nozzle is pressed by the pressing means while the laminate block is being sent out from the second nozzle through the crosshead of the molding machine. The ceramic kneaded material is extruded from the kneaded material, and the kneaded material is extruded while adhering the kneaded material to the entire circumference of the side surface of the laminated body block. A multilayer ceramic capacitor comprising cutting and firing in a vertical plane including a center line and a center line between conductive film intervals, and forming external electrodes on both end faces corresponding to the cut faces of each fired body. Production method.

In carrying out the method of the present invention, the laminate block to be supplied to the crosshead can be manufactured as follows. That is, on the upper surface of a large rectangular ceramic green sheet, the length of the internal electrode of the product capacitor is 2
A rectangular conductive film whose length is twice the vertical dimension and whose horizontal dimension is an integer multiple of the width of the internal electrode of the product capacitor is twice the end margin of the product capacitor. A plurality of unit sheets formed by printing a large number in one row at intervals of the center line of the vertical length of the rectangular conductive film,
The unit sheets to be stacked adjacent to each other are shifted in position so that the center lines of the conductive film spacing portions are in the same vertical plane, and the stacked units are stacked to form an integrated laminated body. By cutting in parallel to the line and with the size of the internal electrode width, a large number of elongated laminated bodies, in which the internal electrodes are exposed on the side surfaces, can be formed from one large laminated body.

According to the method of the present invention, when forming a laminated internal electrode, it is sufficient to form the internal electrode extending to the side surface of the ceramic dielectric body without taking a side margin. It is not necessary to take into account the error of and the cutting error. Further, since the clay of the ceramic dielectric material of the same quality as the ceramic dielectric material can be attached to the side surface of the ceramic dielectric body to be integrally formed,
There is no difference in the coefficient of thermal expansion, etc., and a product that is resistant to heat shock can be obtained. Furthermore, by selecting the shape of the nozzle, it is possible to make a product with an arbitrary outer shape, for example,
The outer shape can be cylindrical, polygonal, elliptic, or the like, and a side margin can be sufficiently provided by the additionally formed calcined body portion of the kneaded clay.

In addition, since the influence of variations such as printing of the conductive film to be the internal electrodes is small, it is possible to manufacture a monolithic ceramic capacitor with small variations in the acquired capacitance.

Hereinafter, the method for manufacturing the laminated ceramic capacitor of the present invention will be further described with reference to examples.

[Example] A dielectric raw material powder containing CaTiO ₃ as a main component and a binder in which a resin was dissolved in an organic solvent were mixed to form a slurry, which was thinly applied on a base film and dried to remove the base film. It peeled and the ceramic green sheet was obtained. The resin content in the slurry used here was 9.0% by weight of the raw material powder.

About the ceramic green sheets prepared,
As shown in the perspective view of FIG. 1, by a printing method, a plurality of rectangular conductive films 2 to be internal electrodes are arranged on the ceramic green sheet 1 at intervals of twice the end margin. Formed.

The sheet 1 on which the conductive film 2 is printed in this way is alternately laminated to the position where the center lines of the gaps 3 to be end margins coincide with the center lines of the rectangular conductive films on the upper and lower adjacent sheets. , It was crimped. This is cut in the thickness direction at the position of the cutting line 4 shown by the one-dot chain line in FIG.
A stick-shaped laminated body block 5 as shown in the perspective view of FIG. 2 was obtained.

On the other hand, using a ceramic raw material and a binder of the same quality as the ceramic green sheet, a binder in an amount smaller than the binder contained in the sheet was mixed and kneaded to prepare a ceramic kneaded material. The resin content contained in the kneaded clay used here was 13.0% by weight of the amount of raw material powder.

After preparing the stick-shaped laminated body block and the ceramic kneaded clay, as shown in the schematic cross-sectional view of the molding machine shown in FIG. 3, the container 6 of the molding machine is circumscribed to the cross-section of the laminated body block 5. A first nozzle 8 having a circular cross-section having a diameter slightly larger than the diameter of a circle is attached to the bottom of the container 6, and a corner corresponding to the shape of the laminate block is attached to the tip of a crosshead 7 provided in the center of the container 6. After mounting the columnar second nozzle 9, the ceramic kneaded clay 10 was filled in the container 6, and the laminated body block 5 was inserted into the portion of the second nozzle 9.

After that, when the inside of the container of the molding machine is pressurized by the screw cam pressure feeding means in the direction of the arrow and the kneaded material 10 is pressure-fed to the first nozzle 8, the ceramic kneaded material 10 is extruded from the first nozzle 8, It is attached to the periphery of the laminate block 5 protruding from the tip of the nozzle 9 and is covered with the block 5, that is, the block 5 is included in the kneaded clay 10 and formed into a columnar formed body 11 and extruded. It was This was taken out sequentially and dried.

The obtained dried body has a shape as shown in the perspective view of FIG. 4, and is perpendicular to the axis of the cylinder at the position of the cutting surface 12 corresponding to the central portion of the gap 3 to be the end margin. When cut, a cylindrical chip 13 as shown in the perspective view of FIG. 5 was obtained. When conductive paste to be external electrodes is applied to both ends of the chip 13 and baked to form external electrodes, a laminated ceramic capacitor having external electrodes 14 as shown in the perspective view of FIG. 6 is obtained.

In this embodiment, since the columnar nozzle was used as the first nozzle, a columnar chip was obtained. However, if the first nozzle is, for example, an octagonal nozzle,
Needless to say, the octagonal tip 15 shown in the figure can be formed, and if a hexagonal nozzle is used, the hexagonal tip can be formed.

[Effects of the Invention] As described above, according to the method of the present invention, the ceramic of the same quality as the monolithic ceramic body is integrated with the monolithic ceramic body to form a chip component having an arbitrary outer shape, and the printing accuracy is improved. It is possible to manufacture a small-sized monolithic ceramic capacitor having a small variation in electrostatic capacitance without being greatly affected by the above.

[Brief description of drawings]

FIG. 1 is a perspective view showing a ceramic green sheet on which a conductive film formed in one step of the method of the present invention is printed. FIG. 2 is a perspective view showing a laminated body block obtained by cutting a ceramic laminated body obtained by pressure-bonding a plurality of ceramic green sheets produced in the step following the above step. FIG. 3 is a schematic cross-sectional view of a molding machine used in the method of the present invention to attach a ceramic kneaded material to a laminated body block to form a cylindrical shaped body. FIG. 4 is a perspective view of a columnar molded body formed in still another step of the method of the present invention. FIG. 5 is a perspective view of a cylindrical chip obtained by cutting the cylindrical molded body. FIG. 6 is a perspective view showing the appearance of a cylindrical laminated ceramic capacitor having external electrodes on the end faces, which is obtained by the method of the present invention. FIG. 7 is a perspective view showing an octagonal chip as an example of a chip having an outer shape different from that shown in FIG. Explanation of reference numerals 1 ... Ceramic green sheet 2 ... Conductive film 3 ... Gap 4 ... Cutting line 5 ... Laminated block 6 ... Molding machine container 7 ... Crosshead 8 ... First nozzle 9 ... No. 2 nozzles 10 …… Ceramic kneaded clay 11 …… Cylindrical compact 12 …… Cut surface 13 …… Cylindrical tip 14 …… External electrode 15 …… Octagonal tip

Claims (3)

[Claims] 1. A stacking unit in which a conductive film of an internal electrode layer is formed on the upper surface of a rectangular ceramic dielectric sheet with an end margin only at one end in the longitudinal direction and without a side margin. A stick-shaped laminated body having a rectangular cross section, which is made by laminating a plurality of sheets so that the side edges are aligned and the end margins are alternately on the opposite sides, is arranged in the central portion as a core body. An outer peripheral body made of a fired material of a ceramic kneaded clay of the same quality as the ceramic of the ceramic derivative sheet in the previous period is formed integrally with the core body so as to surround the entire side surface of the core body with a predetermined outer shape. The body provides a side margin and an insulating outer skin, and the end portions without end margins of the internal electrodes are connected to the external electrodes formed on both end surfaces in the longitudinal direction of the stack. Multilayer ceramic capacitor to be. (A) A conductive film having a constant length to be an internal electrode is formed on the upper surface of a long and narrow ceramic green sheet having a constant width by applying a constant interval in the longitudinal direction without a side margin. The plurality of unit sheets are positioned relative to each other such that the center lines of the conductive films of the constant length and the center lines of the conductive film spacing portions of similar unit sheets that are adjacent to each other are in the same vertical plane. Prepare a laminated body block in which the internal electrodes are exposed on the side surface in the form of being integrated by shifting and stacking; on the other hand, (b) having a hopper-shaped ceramic kneaded clay storage container, and discharging the lower part of the container. At the end, there is a first nozzle for pushing out the ceramic kneaded clay, which has a cross section of an arbitrary shape slightly larger than the cross section of the laminated body block, and inside the first nozzle, the end face of which is also slightly smaller than the end face of the first nozzle. Within And a second nozzle that is directly connected to the crosshead arranged at the center of the ceramic kneaded clay storage container and constitutes the outlet thereof, and further pressurizes the ceramic kneaded clay of the container. In addition, a molding machine having a pressing means for pushing the kneaded clay out of the first nozzle is prepared; (C) The pressing means while feeding the laminate block from the second nozzle through the crosshead of the molding machine. The ceramic kneaded material is extruded from the first nozzle by the above, and the kneaded material is extruded while adhering the kneaded material to the entire circumference of the side surface of the laminated body block. A laminated ceramic comprising cutting and firing in a vertical plane including a constant length conductive film center line and a conductive film interval center line, and forming external electrodes on both end surfaces corresponding to the cut surfaces of each fired body. Capacitor manufacturing method. 3. A rectangular ceramic green sheet having a large size has a vertical dimension which is twice the length of the internal electrode of the product capacitor and is an integral multiple of the width of the internal electrode of the product capacitor. A rectangular conductive film whose horizontal dimension is an arbitrary length is used as the end margin of the product capacitor.
A plurality of unit sheets, which are formed by printing a large number in one row at intervals of a double length, are aligned with the center line of the vertical length of the rectangular conductive film, and the center line of the conductive film interval portion of the unit sheets that are adjacently stacked. So that they are in the same vertical plane, the adjacent ones are displaced from each other and overlapped to form an integrated laminate, which is cut in parallel with the vertical line and with the width dimension of the internal electrode. A large number of elongated laminates having exposed internal electrodes on the side surfaces are formed from one large laminate, and the laminate block is used as a laminate block for supplying the crosshead of the molding machine. 2. The method described in 2.