JP2001057317A - Method for manufacturing laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a laminated ceramic capacitor, which is excellent in productivity and is good in the yield of the manufacture of the capacitor. SOLUTION: The manufacturing method of a laminated ceramic capacitor comprises a first process wherein ceramic green sheets 2 and internal electrodes 1 are thermocompression-bonded to each other in a number fewer than a prescribed number, respectively, to form a laminate green block A; a second process wherein sheets 3 for dissolving the steps in the electrodes 1 of a pattern reverse to that of the electrodes 1 are thermocompression-bonded to the non-formation parts of the electrodes 1 on the surface of the block A, and laminate green blocks B7 with the flat surfaces are formed; a third process wherein a plurality of the fellow blocks B7 are laminated to form a laminate green block C8 laminated with the blocks B7, so that the number of lamination of the sheets 3 becomes equal with the numbers of lamination of the sheets 2 and the electrodes 1; and a four process to form invalid layers 9 on both surfaces of the block 8. Here, the thermocompression-bonding in the laminations in the first, second and third processes is performed in a time shorter than two seconds.

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 multilayer ceramic capacitor.

[0002]

2. Description of the Related Art With the recent miniaturization of electronic devices, multilayer ceramic capacitors are desired to have a small size and a large capacity, and the number of stacked ceramic green sheets and internal electrodes is increasing.

However, with the multi-layering of the ceramic green sheets and the internal electrodes, the thickness difference between the internal electrode portion and the non-formed portion of the manufactured laminated green block increases. Due to this thickness step, there is a problem that the adhesion between the ceramic green sheets in the laminated green block is reduced, and internal structural defects (delamination) and the like are likely to occur. In order to prevent this, usually, the process conditions are set so that the laminating heat-pressing time of the ceramic green sheet and the internal electrode is long, the pressing force is increased, and the influence of the thickness step is minimized.

Hereinafter, a conventional method for manufacturing a multilayer ceramic capacitor will be described with reference to FIG.

[0005] First, an organic binder or the like is added to a barium titanate raw material powder as a main component and kneaded to prepare a ceramic slurry.

Next, the ceramic slurry is applied onto a carrier film by a doctor blade method, and then dried to produce a ceramic green sheet 2.

Next, an electrode paste mainly composed of a metal powder such as palladium is printed on the surface of the ceramic green sheet 2 and dried to form an internal electrode 1 having a predetermined shape.

After that, a predetermined number of the ceramic green sheets 2 on which the internal electrodes 1 are formed are repeatedly laminated, and an ineffective layer 9 in which a predetermined number of the ceramic green sheets 2 are laminated is laminated on both surfaces thereof to produce a laminated green block.
The normal laminating conditions are as follows: a pressing time of 3 to 10 seconds and a pressing force of 20 to 500 kgf / cm ² . It has also been proposed to stack the internal electrode step eliminating sheet 3 having a reverse pattern for eliminating the thickness step between the internal electrode portion and the non-formed portion generated in the laminate green block, if necessary.

Next, after cutting the laminated green block into a predetermined green chip (not shown), the green block is degreased and fired at a predetermined temperature and atmosphere to produce a sintered body of a laminated ceramic capacitor. Note that the green chip has a structure in which one end of the internal electrode 1 is alternately exposed at different end faces every other layer with the ceramic green sheet 2 interposed therebetween at opposite end faces.

Next, after chamfering the sintered body, external electrodes (not shown) are provided on both end surfaces where the ends of the internal electrode 1 are exposed.
To complete a multilayer ceramic capacitor.

[0011]

In the conventional manufacturing method, the ceramic green sheet 2 on which the internal electrode 1 is formed is provided.
In addition to the increase in the number of stacked layers, the stacking of the internal electrode step eliminating sheet 3 in the reverse pattern causes a problem that the working time of the entire stacked green block is increased and the productivity is reduced.
By increasing the pressing time and increasing the pressing force, the lower ceramic green sheet 2 and the internal electrode 1 extend in the planar direction by repeated heating and pressing, and a cutting misalignment easily occurs when cut into a green chip shape. There was also a problem that the yield was reduced.

The present invention solves the conventional problems.
It is an object of the present invention to provide a method of manufacturing a multilayer ceramic capacitor capable of shortening the stacking time of the entire multilayer green block and improving the productivity and the yield of the multilayer ceramic capacitor.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a ceramic green sheet and internal electrodes are formed by alternately heating and pressing a predetermined number of ceramic green sheets and internal electrodes to form a laminated green block. A green sheet A by heating and pressing less than a predetermined number of sheets, respectively, to produce a laminate green block A; A second step of heating and pressing the non-formed portion of the internal electrode on the surface of the block A to produce a laminated green block B having a flat surface, and then laminating a plurality of laminated green blocks B produced in the second step,
A third step of preparing a laminate green block C in which ceramic green sheets and internal electrodes of the required number of layers are laminated, and forming invalid layers on both surfaces of the laminate green block C produced in the third step. The fourth step, and the lamination of the ceramic green sheets and the internal electrodes in the first step, the lamination of the internal electrode step eliminating sheets in the reverse pattern of the second step, and the lamination of the laminate green blocks C in the third step The intended purpose is achieved by performing the crimping time in a time shorter than 2 seconds.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, the step of forming a laminated green block by alternately laminating a predetermined number of ceramic green sheets and internal electrodes by heat and pressure is performed. A first step of preparing a laminate green block A by heat-pressing a number of sheets less than a predetermined number, respectively, and a laminate in which the internal electrode step eliminating sheet having the reverse pattern of the internal electrodes is prepared in the first step. A second step in which a laminate green block B having a flat surface is formed by applying heat and pressure to a portion of the surface of the green block A where an internal electrode is not formed, and then a plurality of laminate green blocks B produced in the second step are laminated. A third step of preparing a laminated green block C in which the number of ceramic green sheets and the number of internal electrodes that are finally required are laminated; A fourth step of forming an ineffective layer on both sides of the produced laminated body green block C, and lamination of the ceramic green sheet and the internal electrode in the first step, and a sheet for eliminating an internal electrode step in a reverse pattern of the second step. This is a method of manufacturing a laminated ceramic capacitor in which the lamination and pressure bonding between the laminated green blocks B in the lamination and the third step are performed in a time shorter than 2 seconds. In the first step, less than a predetermined number of ceramic green sheets and internal electrodes are reduced. After heat-pressing to produce a laminated green block A, a sheet for eliminating internal electrode steps having a reverse pattern is heat-pressed to a portion of the surface of the laminated green block A where no internal electrode is formed, and the laminated green block having a flat surface is formed. By producing B, the pressing force and heat when the laminate green blocks B are heated and pressed together in the third step are evenly distributed. Obtain it possible, Thus it is possible to adhere the heat pressing time is shorter than 2 seconds. By shortening the crimping time, the operation time of the entire multilayer ceramic capacitor is shortened, and the productivity is improved. Also, by laminating the laminate green blocks B, the number of times the lower ceramic green sheet and the internal electrode are subjected to repeated heating and pressurization is reduced, and accordingly, the elongation in the plane direction is reduced. It is possible to prevent the occurrence of cutting misalignment at the time of cutting.

According to a second aspect of the present invention, in the first step, the number of laminated internal electrodes is set such that the internal electrodes formed on the surface of one ceramic green sheet are heat-pressed and the internal electrodes and the non-formed portions 2. The method for manufacturing a multilayer ceramic capacitor according to claim 1, wherein only the nearest integer number of sheets, which is smaller than a value obtained by dividing the thickness after heat-pressing the internal electrode step eliminating sheet of the reverse pattern in the second step at the thickness step, is obtained. After repeatedly forming the green block A by repeating the thermal compression bonding of the integer number of ceramic green sheets and the internal electrodes satisfying the above conditions, the green block A
The thickness difference between the internal electrode and the non-formed portion caused by the above, and the surface of the laminate green block B is heated and press-bonded to the internal electrode step eliminating sheet having a reverse pattern of a thickness in which the thickness after compression becomes substantially equal. It will be flat. That is, the thickness step of each ceramic green sheet caused by thermocompression bonding of the internal electrode formed on the ceramic green sheet surface in advance and the thickness after thermocompression bonding of the sheet for eliminating the internal electrode step difference of the reverse pattern are adjusted. It is possible to accurately determine how many layers of the ceramic green sheets and the internal electrodes are alternately laminated in the first step, and then a flat laminated green block B can be produced by heat-pressing the internal electrode step eliminating sheet having the reverse pattern. By stacking the green blocks B thus manufactured, the stacking process of the entire multilayer ceramic capacitor can be streamlined, and the productivity and the yield of the multilayer ceramic capacitor can be improved. You can do it.

According to a third aspect of the present invention, the thickness of the internal electrode step eliminating sheet having the reverse pattern after the thermocompression bonding is set to 5 times the thickness step between the internal electrode and the non-formed portion.
The method for manufacturing a multilayer ceramic capacitor according to claim 1 or 2, wherein the thickness of the sheet for eliminating the internal electrode step in the reverse pattern after thermocompression bonding is 5 to 30 times the thickness step with the internal electrode. By doing so, the occurrence of poor adhesion between the ceramic green sheets due to the thickness difference between the internal electrode and the non-formed portion generated in the laminate green block A is suppressed, and the laminate green block B having a flat surface is produced. This is also for minimizing the number of laminations of the internal electrode step eliminating sheet having the reverse pattern with respect to the entire laminated green block. When the laminated green blocks B are laminated and pressure-bonded to each other, the pressing time is short, and even when the pressing force is reduced, the laminated green blocks B can be securely adhered to each other. The yield can be improved. If the thickness of the reverse pattern internal electrode step eliminating sheet is less than 5 times the thickness step of the internal electrode per ceramic green sheet, the reverse pattern internal electrode step eliminating sheet that eliminates the thickness step is laminated. The frequency increases and the productivity decreases. On the other hand, when the thickness is more than 30 times the thickness step, the thickness step becomes large when the laminated green block A is manufactured, and the adhesion failure between the ceramic green sheets is likely to occur.

According to a fourth aspect of the present invention, the lamination of the ceramic green sheets and the internal electrodes, the lamination of the sheet for eliminating the internal electrode steps having the reverse pattern, and the lamination of the laminated green blocks B are performed at 20 to 100 kgf / cm. ^The method for producing a multilayer ceramic capacitor according to any one of claims 1 to 3, wherein the pressure is set to 20 to 100 kgf / cm ² by applying a pressure of 20 to 100 kgf / cm ² . Compared to the case where a high pressing force of 100 kgf / cm ² or more is applied, the pressing time of the thermocompression bonding device can be set shorter, and the expansion of the ceramic green sheets and internal electrodes in the plane direction is suppressed, and the green chip is formed. It is possible to prevent the occurrence of a cutting misalignment when cutting into pieces.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a cross-sectional view showing a state in which an internal electrode is heat-pressed on a ceramic green sheet, FIG. 2 is a cross-sectional view of a sheet for eliminating a step of an internal electrode having an inverted pattern, and FIG. 3 is a cross-sectional view of a laminated green block. . In the figure, 2 is a ceramic green sheet, 1 is an internal electrode, 3 is a sheet for eliminating a step of an internal electrode in an inverse pattern, 5 is a pedestal, 6 is a thickness step, 7 is a laminated green block B, 8 is a laminated green block C , 9 indicate an invalid layer.

First, a dielectric slurry containing barium titanate as a main component, an organic binder, a plasticizer, and an organic solvent are respectively weighed, weighed, and kneaded to prepare a ceramic slurry. Next, a ceramic slurry was applied on the carrier film by using a doctor blade method, and then dried to a thickness of 10 mm.
A ceramic green sheet 2 of μm is prepared. Next, an electrode paste mainly composed of nickel metal powder is printed on the surface of the ceramic green sheet 2 using a printing pattern of a predetermined shape, and then dried to form a ceramic green sheet 2 having the internal electrode 1 having a thickness of 20 μm. Separately, the ceramic slurry is printed on a carrier film surface using a printing mask having a pattern opposite to that of the internal electrode 1,
After drying, a sheet 3 for eliminating internal electrode steps having the reverse pattern shown in Table 1 and a predetermined number of ceramic green sheets 2 are heat-pressed to form an ineffective layer 9.

[0021]

[Table 1]

Thereafter, each of the ceramic green sheet 2 on which the internal electrode 1 is formed and the internal electrode step eliminating sheet 3 having the reverse pattern are preliminarily heated to a temperature of 100 ° C. and a pressure of 20 to 200 ° C.
Thermocompression bonding is performed at 120 kgf / cm ^{2 for} 0.5 to 2.0 seconds under a pressurization time, and the thickness step 6 with respect to one part of the internal electrode after the pressure bonding and the thickness of the sheet 3 for eliminating the internal electrode step in a reverse pattern are measured. The results are shown in (Table 1). Based on the measurement results, the number of laminations of the ceramic green sheet 2 and the internal electrode 1 in the first step was determined, respectively, and the results are shown together in (Table 1).

Next, the ceramic green sheet 2 on which the second-layer internal electrode 1 is formed is superimposed on the surface of the first-layer ceramic green sheet 2 on which the internal electrode 1 is formed with a predetermined size shifted in the longitudinal direction of the internal electrode 1. Temperature 100 ° C, pressure 2
The thermocompression bonding is performed at 0 to 120 kgf / cm ^{2 for} 0.5 to 2.0 seconds. Subsequently, the ceramic green sheet 2 on which the third-layer internal electrode 1 is formed is stacked so that the internal electrode 1 is directly over the first-layer internal electrode 1, and heat-pressed under the same conditions. The ceramic green sheets 2 on which the internal electrodes 1 are formed in this manner are alternately moved back and forth in the longitudinal direction of the internal electrodes 1 so that the number of laminated ceramic green sheets 2 and the internal electrodes 1 is as shown in Table 1 below. The laminate green block A is prepared by repeating the lamination heat compression.

Then, a sheet 3 for eliminating the internal electrode step in a reverse pattern is placed on the non-formed portion of the internal electrode 1 on the surface of the laminate green block A, and the laminate is heated and pressed under the above conditions.
A laminate green block B7 having a flat surface is manufactured.

Thereafter, a plurality of laminated green blocks B7 are repeatedly laminated and heated and pressed together until the number of laminated internal electrodes 1 reaches 120, and a laminated green block C8 is formed.
Is prepared.

Next, the ineffective layer 9 is superimposed on both surfaces of the laminated green block C8, and the laminate is heated and pressed under the same conditions to produce a laminated green block.

Next, after cutting the laminated green block into a predetermined green chip shape, the laminated green block is degreased and fired at a predetermined temperature and atmosphere to produce a sintered body of a laminated ceramic capacitor. The green chip has a structure in which one end of the internal electrode 1 is alternately exposed at different end faces on both sides facing each other with the ceramic green sheet 2 interposed therebetween.

Then, after chamfering the sintered body, external electrodes are formed on both end surfaces where the ends of the internal electrode 1 are exposed, and a multilayer ceramic capacitor having a length of 3.2 mm and a width of 1.6 mm is completed. Was.

It is assumed that the percentage of defective cutting displacement of the green chip obtained by the first embodiment and the green chip manufactured by the conventional method and the time required for manufacturing the multilayer green block of the conventional multilayer ceramic capacitor are 100. Table 1 shows the production time ratio of each of the green blocks of the laminated body according to the present invention.

As shown in (Table 1), the green chip manufactured by using the green block A in which the number of the internal electrodes 1 is 5 to 30 is lower than that of the conventional method. It can be seen that it is extremely low.
In the conventional method, it is considered that the lower ceramic green sheet 2 and the internal electrode 1 extend in the plane direction by repeated lamination and heating and pressing 120 times, and as a result, a cutting failure is considered to have occurred.
However, also in the present invention, when the pressurization time is 2 seconds, a cutting failure tends to occur. Therefore, it is clear that the pressurization time needs to be controlled to a time shorter than 2 seconds. In addition, it can be seen that the production time of the laminated green block is reduced to almost half as compared with the conventional method. In the present embodiment, the internal electrode 1 is formed by printing on the surface of the ceramic green sheet 2. However, a method is used in which the internal electrode 1 is formed by printing on the surface of the carrier film in advance and thermally transferred to the surface of the ceramic green sheet 2. This has the same effect. In addition, the thickness of the ceramic green sheet 2 is set to 20.
μm, and the internal electrodes 1 of the laminated green block are 120 layers, but the present invention is not limited to this.

[0031]

As described above, the method for manufacturing a multilayer ceramic capacitor according to the present invention comprises the steps of alternately laminating a predetermined number of ceramic green sheets and internal electrodes by heat and pressure to produce a laminated green block. The first step of alternately heat-pressing a smaller number of electrodes than a predetermined number to produce a laminate green block A, and the internal electrode step eliminating sheet having a pattern opposite to that of the internal electrodes was produced in the first step. A second step of heat-pressing the surface of the laminate green block A on the non-formed portion of the internal electrode to produce a laminate green block B having a flat surface;
A ceramic green sheet that finally needs the laminated body green blocks B produced in the second step,
A third step of repeating the lamination until the number of layers of the internal electrode to produce a laminated green block C, and a fourth step of laminating an ineffective layer on both surfaces of the laminated green block C,
In addition, by performing each lamination time in less than 2 seconds, the lamination time of the entire laminated green block is shortened, and the productivity and yield of the laminated ceramic capacitor can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which an internal electrode is heated and pressed on a ceramic green sheet of the present invention.

FIG. 2 is a cross-sectional view of an internal electrode step eliminating sheet having the same reverse pattern.

FIG. 3 is a cross-sectional view of a laminated green block.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 internal electrode 2 ceramic green sheet 3 sheet for eliminating internal electrode step in reverse pattern 5 pedestal 6 thickness step per one ceramic green sheet 7 laminated green block B 8 laminated green block C 9 invalid layer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kazumasa Konishi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kazuhiro Komatsu 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. ( 72) Inventor Yoshihiro Yamaguchi 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Satoru Oikawa 1006 Odaka Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. AG00 AH05 AJ01 AJ02 5E082 AA01 AB03 BC38 EE04 EE35 FG06 FG18 FG26 FG54 JJ03 JJ15 LL01 LL02 LL03 MM22 MM24 MM32 PP05 PP07 PP09

Claims (4)

[Claims] 1. A step of forming a laminated green block by alternately laminating a predetermined number of ceramic green sheets and internal electrodes by heat and pressure bonding to form a laminated green block by laminating a plurality of ceramic green sheets and internal electrodes by a number smaller than a predetermined number. A first step of producing a body green block A, and then forming a green sheet for eliminating an internal electrode step having a pattern opposite to that of the internal electrodes on the surface of the laminate green block A produced in the first step. A second step of producing a laminated green block B having a flat surface by heat-pressing the formed portion, and then laminating a plurality of laminated green blocks B produced in the second step, and finally forming a ceramic green A third step of producing a laminate green block C laminated to have the number of sheets and internal electrodes,
It consists of a fourth step of forming ineffective layers on both sides of the laminate green block C produced in the third step, and the lamination of the ceramic green sheets and the internal electrodes in the first step, and the internal electrode steps in the reverse pattern of the second step A method for manufacturing a laminated ceramic capacitor, comprising laminating sheets for use and laminating and pressing the laminated green blocks B in the third step in a time shorter than 2 seconds. 2. The number of laminated internal electrodes in the first step is determined by the thickness difference between the internal electrodes formed on the surface of one ceramic green sheet and the non-formed part after the internal electrodes are heat-pressed, and the number of the internal electrodes is reduced in the second step. The method for manufacturing a multilayer ceramic capacitor according to claim 1, wherein only the nearest integer number of sheets, which is smaller than a value obtained by dividing the thickness of the pattern after removing the internal electrode step by heating and pressing, is closest. 3. The thickness of the sheet for eliminating the internal electrode step in the reverse pattern after thermocompression bonding is 5 to 30 times the thickness step between the internal electrode per one ceramic green sheet and the non-formed portion. 3. The method for manufacturing a multilayer ceramic capacitor according to item 1. 4. Laminating a ceramic green sheet and an internal electrode, laminating a sheet for eliminating an internal electrode step in a reverse pattern,
And the stack of the green blocks B is 20 to 1
The method for producing a multilayer ceramic capacitor according to claim 1, wherein the method is performed at a pressure of 00 kgf / cm ² .