JPH0745473A - Manufacture of multilayer ceramic capacitor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a multilayer ceramic capacitor comprising a plurality of dielectric layers and inner electrode layers laminated alternately in which the level difference of sintered material due to the inner electrode layer is suppressed and the productivity and mountability are enhanced while preventing the internal structural defect which occurs especially in high multilayer device at the time of firing. CONSTITUTION:Ceramic layers 6a, 6b are inserted, in parallel with the inner electrode 3a, into dielectric layers 1 on the opposite side faces at the opposite ends of an effective layer 4 where the inner electrode 3a is not present and into the dielectric layer 1 only at the part of the inner electrode 3a connected with the outer electrode 3a in order to correct the thickness of the inner electrode, and then the molded item is fired. Consequently, the level difference of sintered body can be suppressed, interlayer bonding is enhanced at the time of pressing a high laminate and inner structural defect is suppressed, resulting in a multilayer ceramic capacitor excellent in productivity, mountability, and characteristics.

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 monolithic ceramic capacitor used in various electronic devices.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic circuit devices, the use of highly laminated and high-capacity ceramic capacitors has increased, and inventions have been made that prevent internal structural defects and increase the mounting density on a circuit board.

A conventional monolithic ceramic capacitor will be described below with reference to the drawings.

As shown in FIGS. 6 and 7, the monolithic ceramic capacitor has one inner electrode 3a and one second inner electrode 3a connected to a dielectric ceramic layer 1 and first outer electrodes 2a provided alternately in the vertical direction. A plurality of internal electrode layers 3 composed of the other internal electrode 3b connected to the external electrode 2b are laminated, and the effective layer 4 mainly determines the capacitance characteristics and the other upper ineffective layer 5a and lower ineffective layer 5b. It is configured.

In the conventional manufacturing method, in order to form the effective layer 4, the ceramic green sheets and the electrode sheets are alternately laminated, or the ceramic green sheets on which electrodes are printed are laminated to form a molded body. After that, cutting and firing were performed to prepare a sintered body, and then external electrodes were applied and baked to obtain a monolithic ceramic capacitor.

In the above-mentioned molded body, the total thickness of the portion where the internal electrode layer 3 is present as shown in FIG. 6A and the total thickness of both side portions where the internal electrode layer 3 is not present in FIG. The total thickness was different. Further, the total thickness of the portion where the facing internal electrode layer 3 is present as shown by c in FIG. 7 and the external electrode 2a where the facing internal electrode layer 3 is not present as shown by d,
2b and the total thickness of the front and rear parts connected to the inner electrode layer 3
The thickness was different by the difference in the number of electrodes.

In a low number of laminated monolithic ceramic capacitors, this is hardly a problem, but in a high monolithic ceramic capacitor in which thin layer ceramic sheets are laminated in multiple layers, the difference in partial total thickness in the molded body is a factor. When it was made into a sintered body as shown in FIGS. 8 and 9, the sintered body was a distorted rectangular parallelepiped. Also, when the formed bodies are laminated or after being laminated, they are pressed to improve the bonding between the ceramic green sheets and cut and fired. However, when the laminated body is highly laminated, the total thickness of the internal electrodes becomes large so that the laminated bodies are laminated. Inadequate bonding between the ceramic green sheets occurs on the side surface of the molded body, resulting in stacking failure and internal structural defects during firing. Further, in the method of repeating the lamination of the ceramic green sheets and the printing of the internal electrodes, electrode printing was difficult due to the step difference of the laminated printed surface caused by the thickness of the internal electrodes as the number of laminated layers increased.

[0008]

As described above, according to the conventional method, in the high monolithic ceramic capacitor, the shape of the sintered body is not normal and the workability at the time of mounting is deteriorated, and the internal structure is low. There is a problem that a defect occurs, and even a printing method makes it difficult to print electrodes.

The present invention solves the above-mentioned problems of the prior art by making it possible to form a sintered body that does not distort the shape and prevent the occurrence of internal structural defects. Further, in the method of repeating electrode printing and ceramic green sheet lamination, It is an object of the present invention to provide a method for manufacturing a monolithic ceramic capacitor, which can improve the printability of, and has good productivity and workability during mounting.

[0010]

In order to solve the above-mentioned problems, a method for manufacturing a multilayer ceramic capacitor according to the present invention is applied to both the dielectric layers on both sides where no internal electrode layer exists and the internal electrodes facing each other. This is a method of firing a molded body formed by inserting a ceramic layer in parallel with the internal electrodes in the dielectric layers in the front and rear portions where there is no.

[0011]

In the method of the present invention, the thickness of the portion where the internal electrode layer is present and the portion where only the dielectric layer is present or the portion where only half of the internal electrodes are present are approximately the same, and the pressing pressure at the time of forming the molded body is uniform. As a result, the strain of the molded body is reduced, the occurrence of internal structural defects can be reduced, and the shape of the sintered body is not distorted. Further, even during manufacturing, the step due to the electrode thickness is always eliminated, the homogeneity during lamination is maintained, and the printability of the electrode is improved in the method of repeating the electrode printing and the lamination of the ceramic green sheets. Furthermore, by increasing the compressive deformation of the inserted ceramic layer, good adhesion of the laminated molded body can be achieved under mild pressing conditions, and the pressing conditions can be relaxed, so that the short-circuit rate can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 5 showing an embodiment of the present invention, the same components as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

(Example 1) As shown in FIGS. 1 to 3, on a ceramic green sheet made of a dielectric powder containing barium titanate as a main component and an organic binder and forming a dielectric layer 1 having a thickness of 8 μm after firing. Then, 80 sheets of the Pd internal electrode paste printed so as to have a thickness of 1.5 μm after firing are laminated to form 80 effective layers 4, and each of the upper and lower sides of the effective layer 4 has a thickness of about 200 μm after sintering. Upper invalid layer 5
In a molded body having a and a lower ineffective layer 5b, an effective layer after firing is applied only to the portion of the internal electrode 3a (or 3b) connected to the external electrode without both of the opposing internal electrodes 3a and 3b indicated by d. 4 opposing internal electrodes 3a, 3
13.5 μm that does not exceed twice the thickness of the dielectric layer 1 between b
4 layers (or 5 layers) are inserted for every 18 layers of the effective layer 4 to increase the thickness of the ceramic layer 6a, and the internal electrodes 3a and 3b shown by b are inserted.
The ceramic layer 6b having the same thickness as described above is provided in the portion where no
Was formed into 9 layers for every 9 layers of the effective layer 4. As a comparative example, a molded body in which the ceramic layers 6a and 6b were not inserted was also manufactured.

The method for producing this molded article will be described in detail below. Electrode print sheets A1 and A2 were produced by printing the internal electrode paste of Pd on the ceramic green sheet having a thickness of 8 μm after firing so as to have a thickness of 1.5 μm after firing as shown in FIG. Further, as shown in FIG. 5, ceramic printed sheets B1 and B2 printed on the electrode printed sheets A1 and A2 on which the Pd electrodes are printed so as to have a thickness of 13.5 μm after sintering the ceramic paint other than the Pd electrode portions are also provided. It was made. First, ceramic green sheets were laminated to a thickness of about 200 μm after sintering to form a lower ineffective layer 5b. Electrode printing sheets A1 and A2 on which internal electrodes are printed so as to be connected to different external electrodes after cutting
2 in order of the electrode print sheet A1 and the electrode print sheet A2
Layers were laminated. Next, a ceramic printed sheet B1 having an electrode pattern connected to the same external electrode as the electrode printed sheet A1 is laminated, and an electrode printed sheet A1 and an electrode printed sheet A2 are alternately laminated one by one on each of four layers, A ceramic printing sheet B2 having an electrode pattern connected to the same external electrode as the electrode printing sheet A1 is laminated thereon, and four layers each of the electrode printing sheets A1 and A2 are alternately laminated in that order on each layer, and ceramic printing is performed again. The sheets B1 are repeatedly laminated in this order, and the electrode printing sheets A1 and A2 and the ceramic printing sheet B are formed on the lower ineffective layer 5b.
81 layers including 1 and B2 were laminated to form an effective layer 4.
Next, after stacking the same upper ineffective layer 5a as above, the upper ineffective layer 5a was cut, and a molded body having a different number of stacked layers and having a ceramic layer inserted as shown in FIG. 1 was produced. In the comparative example, only the electrode printing sheets A1 and A2 are used to form the effective layer 4, and the electrode printing sheets A1 and A2 are alternately laminated to form 81 layers.
The upper ineffective layer 5a and the lower ineffective layer 5b were laminated and cut in the same manner as above to produce a molded body.

These compacts were fired at 1320 ° C. to obtain sintered bodies. As shown in FIG. 3, the internal structure of the sintered body in which the ceramic layers 6a and 6b are inserted is widened every 18 layers between the internal electrodes 3a (or 3b) connected to the external electrodes, and the internal electrodes 3a in the vicinity thereof are widened. (Or 3b) is not a straight line and is deformed in the vicinity of the opposing internal electrodes 3b (or 3a).
b was parallel, and the overall shape was a substantially normal rectangular parallelepiped sintered body with no distortion.

On the other hand, in the sintered body in which the ceramic layer is not inserted, as shown in FIGS. 8 and 9 of the above-mentioned conventional example, the internal electrodes 3a and 3b become curved as they go outside the central portion. Moreover, the overall shape was such that the portion without the internal electrodes 3a and 3b was thinner than the portion with the internal electrodes 3a and 3b, and the sintered body was a distorted rectangular parallelepiped. In addition, in the sintered body in which the ceramic layers 6a and 6b were inserted, no internal structural defect was observed, whereas in the sintered body in which the ceramic layer was not inserted, one having an internal structural defect of 3% was detected. It was

As described above, according to this embodiment, by inserting the ceramic layers 6a and 6b so as to correct the shape step of the sintered body due to the thickness of the internal electrodes 3a and 3b, the shape of the sintered body is changed. Since it can be made into a substantially rectangular parallelepiped, malfunctions at the time of attaching the external electrode can be eliminated, the shape of the product is not distorted, the product can be attached correctly, and the mountability can be improved. In addition, the occurrence of internal structural defects can be reduced, and the product yield can be improved.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

A ceramic green sheet made of a dielectric powder containing barium titanate as a main component and an organic binder is laminated after sintering to a thickness of about 150 μm to form a lower ineffective layer 5b, and 1.5 μm after firing. The internal electrode paste of Pd is printed so that the thickness becomes thick, and after firing, the ceramic green sheets to be the dielectric layer 1 having a thickness of 10 μm are laminated, and by repeating this printing lamination, 70 effective layers 4 are formed. In a molded body provided with an upper ineffective layer 5a having a thickness of about 150 μm after sintering on the layer 4, the internal electrode 3a (or the internal electrode 3a connected to the external electrode shown in d) does not have both of the opposing internal electrodes 3a and 3b. 3b) only, 6 layers (or 7 layers) of ceramic layers 6a having a thickness of 7.5 μm after firing are inserted for every 10 layers of the effective layer 4, and
A ceramic layer 6b having the same thickness as that described above is formed on the portions where the internal electrodes 3a and 3b shown in FIG.
A layered insert was obtained. Ceramic layer 6 as a comparative example
A molded body in which a and 6b were not inserted was also manufactured.

As a specific method for inserting the ceramic layer, the ceramic layer is printed by printing the ceramic layer on the surface on which the predetermined Pd electrode paste is printed so as not to overlap the internal electrodes 3a (or 3b) with the reverse pattern of the electrodes. went.

These molded bodies were fired at 1320 ° C. to obtain sintered bodies. The internal structure of the sintered body in which the ceramic layers 6a and 6b are inserted is widened every 10 layers between the internal electrodes 3a (or 3b) in the portion connected to the external electrodes, as shown in FIG. The internal electrodes 3a (or 3b) in the vicinity of the internal electrodes 3b (or 3b) facing each other are not straight lines.
Although it deforms in the vicinity of the presence of a), the internal electrodes 3a and 3b are parallel except for the inflection portion, and the overall shape is a substantially normal rectangular parallelepiped sintered body.

On the other hand, in the sintered body in which the ceramic layer is not inserted, as shown in FIGS. 8 and 9 of the above-mentioned conventional example, the internal electrodes 3a and 3b become curved as it goes outside from the central portion. Moreover, the overall shape was such that the portion without the internal electrodes 3a and 3b was thinner than the portion with the internal electrodes 3a and 3b, and the sintered body was a distorted rectangular parallelepiped. In addition, in the sintered body in which the ceramic layers 6a and 6b were inserted, no internal structural defect was observed, whereas in the sintered body in which the ceramic layer was not inserted, one having an internal structural defect of 2% was detected. It was In addition, defective printing occurred due to unevenness of the printing surface during the production of the molded body.

As described above, according to this embodiment, by inserting the ceramic layers 6a and 6b so as to correct the shape step of the sintered body due to the thickness of the internal electrodes 3a and 3b, the shape of the sintered body is changed. Since it can be made into a substantially rectangular parallelepiped, malfunctions at the time of attaching the external electrode can be eliminated, the shape of the product is not distorted, the product can be attached correctly, and the mountability can be improved. In addition, the occurrence of internal structural defects can be reduced, printability can be improved, and product yield can be improved.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

A ceramic green sheet made of a dielectric powder containing barium titanate as a main component and an organic binder was sintered and laminated to a thickness of about 100 μm to form a lower ineffective layer 5b. An internal electrode pattern of Pd having a thickness of 1.1 μm after firing formed by printing on a film was transferred thereon, a dielectric green sheet having a thickness of 4 μm after firing was laminated, and this electrode transfer and ceramic green sheet lamination were performed. By repeating this, 90 effective layers 4 were formed, on which a ceramic green sheet was sintered and laminated so as to have a thickness of about 100 μm, and an upper ineffective layer 5a was provided, as shown by d in FIG. After sintering as shown in Experimental Examples a, b and c of (Table 1), only the internal electrode 3a (or 3b) without both of the opposing internal electrodes 3a and 3b was present, and the dielectric layer 1 A ceramic layer 6a having a thickness of 1 layer of 4 μm, a thickness of 2 layers of 8 μm, and a thickness of 3 layers of 12 μm, and a portion (not shown) where internal electrodes do not exist is shown in Table 1. Same as above A molded body by inserting the number of layers shown in the ceramic layer thickness, respectively (Table 1), to prepare a molded body which does not insert the ceramic layer as a comparative example.

[0027]

[Table 1] The ceramic layer can be inserted by transferring a ceramic green sheet printed on the film on which the Pd internal electrode pattern is printed in the reverse pattern of the Pd electrode so that it does not overlap with the electrode pattern. went.

Also, a molded body was produced in which the ceramic sheet of the ceramic layer to be inserted here was softer than the ceramic layer of the normal effective layer portion and had a large compressive deformation during the laminating press.

These molded bodies were fired at 1320 ° C. to obtain sintered bodies. The firing was performed by removing the binder in nitrogen gas, firing in nitrogen gas up to 900 ° C., and firing in air at 900 ° C. or higher.

Experimental examples a, b, c in which ceramic layers were inserted
The sintered body of No. 1 was fired into a rectangular parallelepiped whose appearance was almost the same as in Examples 1 and 2. However, as shown in Experimental Example c, in the example in which the ceramic layers having the thickness of three layers of the dielectric layer 1 are inserted, the internal electrode layers near the inserted ceramic layers are considerably deformed and stretched, and the internal electrode layers are When the thickness was thin, the probability that the internal electrodes would be broken at the stretched portion was high, and the product capacity was low compared to other experimental examples. When the thickness of the ceramic layer to be inserted is equal to or less than the thickness of two layers of the dielectric layer 1, the internal electrodes are not stretched so much, and the product capacity is almost the same as that when the ceramic layer is not inserted.

Further, when the inserted ceramic layer has a large compressive deformation, it is possible to perform lamination under a milder press condition than that of a normal compressible one. As a result, when the usual compressible ceramic layer was inserted, the short-circuit rate of the product generated was 5%. When the ceramic layer with large compressive deformation was inserted, 0%
It became%.

In the third embodiment, as a method for inserting the ceramic layer, a ceramic green sheet is printed and formed on the film in a pattern reverse to the Pd electrode so as not to overlap with the Pd electrode pattern. It goes without saying that the same molded body can be obtained and the same effect can be obtained even if the transfer is performed in the same manner as the pattern.

[0033]

As is apparent from the above description, the manufacturing method according to the present invention can manufacture a high-capacity, high-capacity ceramic capacitor without damaging the shape, and can prevent the occurrence of internal structural defects, thus improving the productivity. It is possible to obtain a monolithic ceramic capacitor having excellent mountability and characteristics.

[Brief description of drawings]

FIG. 1 is an external perspective view of a sintered body manufactured by a method for manufacturing a monolithic ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the same sintered body in a width direction.

FIG. 3 is a cross-sectional view of the main part of the sintered body in the length direction.

FIG. 4 is a cross-sectional view of essential parts in the longitudinal direction when the thickness of a ceramic layer into which a sintered body is inserted according to the method for manufacturing a multilayer ceramic capacitor of Example 3 of the present invention is changed.

FIG. 5 is a perspective view showing an electrode pattern and a ceramic printing pattern in the method for manufacturing a monolithic ceramic capacitor according to Example 1 of the present invention.

FIG. 6 is a cross-sectional explanatory view of a monolithic ceramic capacitor in the width direction.

FIG. 7 is an explanatory cross-sectional view of a monolithic ceramic capacitor in the length direction.

FIG. 8 is an explanatory cross-sectional view in the width direction of a sintered body according to a conventional method for manufacturing a monolithic ceramic capacitor.

FIG. 9 is an explanatory view of a cross section of the sintered body in the longitudinal direction.

[Explanation of symbols]

 1 Dielectric layer 2a, 2b External electrode 3a, 3b Internal electrode 4 Effective layer 5a Upper ineffective layer 5b Lower ineffective layer 6a, 6b Ceramic layer

Claims (8)

[Claims] 1. A monolithic ceramic capacitor in which a plurality of dielectric layers and internal electrodes are alternately laminated, wherein an internal electrode facing only the dielectric layers on both sides without the internal electrode layers and the external electrodes. A method of manufacturing a monolithic ceramic capacitor, comprising: firing a molded body formed by inserting a ceramic layer in parallel with the internal electrodes on the front and rear dielectric layers where both electrodes do not exist. 2. The total thickness of the ceramic layers to be inserted, which is approximately the same as the total thickness of the internal electrode layers, is set to one of the internal electrode and the thickness of the dielectric layer sandwiched between the internal electrode layers. The method for producing a monolithic ceramic capacitor according to claim 1, wherein the thickness is divided into a thickness not exceeding twice the total thickness and the layers are inserted between predetermined layers. 3. When the thickness of one ceramic layer to be inserted is n times as large as the thickness of one internal electrode, both side surfaces where the internal electrode layer does not exist are formed at almost every n layers of dielectric layers of the effective layer.
The front and rear parts where only the internal electrodes connected to the external electrodes and the opposing internal electrodes do not exist are approximately 2 of the effective dielectric layer.
The method for manufacturing a monolithic ceramic capacitor according to claim 1, wherein a ceramic layer is inserted every n layers. 4. An internal electrode paste is printed on a ceramic green sheet, and an effective layer is formed by laminating a plurality of the pastes, and an upper ineffective layer is formed by laminating several ceramic green sheets above and below the effective layer. In manufacturing a monolithic ceramic capacitor made by firing a molded body having a lower ineffective layer formed thereon, a green sheet printed with a ceramic paint in the reverse pattern of the internal electrodes is provided on the green sheet printed with the internal electrodes as a predetermined effective layer. 4. The method for manufacturing a monolithic ceramic capacitor according to claim 1, wherein the multi-layer ceramic capacitors are laminated for each number. 5. A lower ineffective layer is formed by laminating a plurality of ceramic green sheets, printing of an internal electrode paste and lamination of the ceramic green sheets are repeated thereon to form an effective layer, and a ceramic layer is further formed on the effective layer. In the manufacture of a multilayer ceramic capacitor obtained by firing a molded body formed by forming an upper ineffective layer by stacking several green sheets, the surface of the internal electrode paste is printed on the surface of the electrode 4. The method for manufacturing a monolithic ceramic capacitor according to claim 1, wherein the ceramic paint is printed in a reverse pattern. 6. An effective layer is formed by stacking several ceramic green sheets to form a lower ineffective layer, and transferring the electrode pattern formed on the film thereon and stacking the ceramic green sheets alternately. On the film on which the electrode pattern is formed, in the production of a laminated ceramic capacitor obtained by firing a molded body made by forming an upper ineffective layer by laminating several ceramic green sheets on the 2. A sheet in which a ceramic paint is printed in a reverse pattern of electrodes is transferred for each predetermined stack of effective layers.
4. A method for manufacturing a monolithic ceramic capacitor according to any one of 2 and 3. 7. An effective layer is formed by forming a lower ineffective layer by laminating a plurality of ceramic green sheets, and alternately repeating the transfer of the electrode pattern formed on the film and the lamination of the ceramic green sheets. In order to manufacture a monolithic ceramic capacitor, which is made by forming an upper layer ineffective layer by laminating several ceramic green sheets on top of this, a sheet coated with ceramic paint in the reverse pattern of the electrodes on the film is effective. The method for producing a monolithic ceramic capacitor according to claim 1, wherein transfer is performed for each predetermined lamination of layers. 8. The multilayer ceramic according to claim 4, wherein the coating film of the ceramic paint to be printed is softer than the effective layer ceramic layer and has a large deformation at the time of lamination press. Capacitor manufacturing method