JPH0752697B2 - Method for manufacturing monolithic ceramic capacitor - Google Patents

Description

The present invention relates to a method for manufacturing a monolithic ceramic capacitor, and more particularly to a method for manufacturing a monolithic ceramic capacitor that is small in size and capable of obtaining a large capacity. is there.

[Prior Art] The demand for miniaturization and large capacity of multilayer ceramic capacitors is infinitely increased in combination with miniaturization and high performance of electronic devices to which these are applied.

As a means for reducing the size and increasing the capacity of the monolithic ceramic capacitor, it is possible to consider using a ceramic material having a high dielectric constant, but such a method naturally has its limits. Therefore, at present, as a means for satisfying the above-mentioned demands, it is considered that the most effective method is to reduce the distance between the pair of internal electrodes sandwiching the dielectric made of ceramic. . Thus, in order to reduce the distance between the internal electrodes, it is necessary to reduce the thickness of the raw ceramic layer or sheet used in the manufacture of the laminated ceramic capacitor.

[Problems to be Solved by the Invention] In the process of manufacturing a laminated ceramic capacitor, there is a step of forming a metal layer containing a metal to be an internal electrode in a predetermined pattern on a raw ceramic layer or a sheet. Such a metal layer is usually formed by using a wet printing method such as a screen printing method. In order to enable this printing method, the metal serving as the internal electrode contains a suitable solvent. It must be able to be handled as a paste. However, when the thickness of the green ceramic layer or sheet is as thin as, for example, about 10 μm, a problem as shown in FIG. 17 is often encountered.

In FIG. 17, the metal paste layer 2 is provided between the green ceramic layers 1.
Is shown in an enlarged sectional view. The solvent contained in the metal paste layer 2 has the property of swelling the raw ceramic layer 1 and further dissolving it. First
In FIG. 17, 3 indicates a swollen portion. Such a swelled portion 3 is formed especially when the thickness of the raw ceramic layer 1 is small.
The probability that the raw ceramic layer 1 extends while penetrating in the thickness direction is extremely high. Therefore, when a monolithic ceramic capacitor is manufactured with the swollen portion 3 as shown in FIG. 17 left, pinholes or the like are generated in the ceramic layer existing between the internal electrodes, which causes a short circuit between the internal electrodes. In addition, there is a high possibility that characteristic defects such as a low dielectric breakdown voltage between the internal electrodes occur.

Therefore, the present invention, while reducing the thickness of the raw ceramic layer, it is possible to minimize the adverse effect of the solvent leaching from the metal paste layer on the raw ceramic layer,
It is an object of the present invention to provide a method for manufacturing a monolithic ceramic capacitor.

[Means for Solving Problems] The present invention is characterized in that the following steps are repeatedly performed in order to solve the problems described above. A. Preparing first and second carrier films, b. Forming a first green ceramic layer on the first carrier film, and further forming internal electrodes on the first green ceramic layer. A step of preparing a first laminate in which a metal paste layer containing a metal is formed in a predetermined pattern, c. The solvent contained in the metal paste layer formed on the first green ceramic layer is mixed with another ceramic. Evaporating to a degree that does not adversely affect the layers, d. Preparing a second laminate having a second green ceramic layer formed on the second carrier film, e. The first or second While placing one of the raw ceramic layers at the reference position, the metal paste layer obtained by evaporating the solvent is sandwiched between the first raw ceramic layer and the second raw ceramic layer. So as to overlap, the first
Alternatively, with the other one of the second green ceramic layers held by the first or second carrier film,
A first crimping step of thermocompression-bonding onto one of the raw ceramic layers using a thermocompression-bonding member containing a heater, f. One of the first and second raw ceramic layers is a reference position. The other of the first or second green ceramic layer so that the first green ceramic layer and the second green ceramic layer overlap with each other without sandwiching the metal paste layer. A second crimping step of thermocompressing on one of the raw ceramic layers by using a thermocompression-bonding member having a built-in heater while being held by the first or second carrier film, g. A first removing step of removing the first carrier film from the first laminate, and h. A second removing step of removing the second carrier film from the second laminate.

[Operation and Effect of the Invention] In the present invention, the first and second green ceramic layers are prepared in a state of being formed on the first and second carrier films, respectively. Further, when stacking the first and second green ceramic layers, the green ceramic layer to be stacked on the green ceramic layer placed at the reference position, that is, the green ceramic layer to be moved in such a stacking operation is always the first or It is in a state of being held by the second carrier film. Therefore, the first and second carrier films serve to prevent damage to the first and second green ceramic layers held by the first and second carrier films and to supplement the mechanical strength of the first and second green ceramic layers. The layer thickness can be reduced to a thickness of, for example, about 2 to 3 μm. From this, the obtained monolithic ceramic capacitor can meet the requirements for small size and large capacity.

The present invention also includes the step of preparing a first laminate in which a first green ceramic layer is formed on the first carrier film and a metal paste layer is formed on the green ceramic layer. . By adopting this step, the influence of the solvent exuding from the metal paste layer can be kept within the thickness range of the first green ceramic layer. In addition, after the step of preparing such a first laminate, the solvent contained in the metal paste layer is
Evaporation of such solvent is performed to the extent that it does not adversely affect the other ceramic layers in subsequent steps.

Further, according to the present invention, the metal paste layer is sandwiched between the first
A first crimping step for stacking the green ceramic layer with the second green ceramic layer, and stacking the first green ceramic layer with the second green ceramic layer without interposing the metal paste layer. Since the second pressure-bonding step is performed, both of the first pressure-bonding step and the second pressure-bonding step are performed. As a result, the first and second metal paste layers facing each other in the stacking direction are formed. Both of the second green ceramic layers will intervene. In addition, as described above, the solvent contained in the metal paste layer formed on the first green ceramic layer does not adversely affect other ceramic layers before the first and second pressure bonding steps. Has been evaporated up to. From these facts, as described above, even if the solvent contained in the metal paste layer causes swelling in the first green ceramic layer at the stage of preparing the first laminate, the inconvenience caused by the swelling is The two green ceramic layers make it possible to stop reliably. Therefore, when a laminated ceramic capacitor is obtained through the subsequent firing step, even if a defect such as a pinhole occurs in the first ceramic layer portion corresponding to the first green ceramic layer, Such defects are advantageously covered by the second ceramic layer corresponding to the two green ceramic layers, resulting in characteristic defects such as a short circuit between the internal electrodes and a low dielectric breakdown voltage between the internal electrodes. Therefore, a highly reliable multilayer ceramic capacitor can be manufactured.

Further, in the first and second pressure bonding steps, since the thermocompression bonding member including the heater is used, it is possible to obtain a reliable pressure bonded state while maintaining an accurate laminated state.

[Embodiment] FIGS. 1 to 9 are views for explaining one embodiment of the present invention. Hereinafter, this embodiment will be described in the order of steps for obtaining a laminated ceramic capacitor as a finished product.

First, as shown in FIG. 1 and FIG. 2, respectively,
And the second carrier films 11 and 12 are prepared, respectively. These carrier films 11 and 12 are made of a flexible film material such as polyethylene terephthalate, polypropylene, etc.
The thickness is selected to be about m.

Next, as shown in FIG. 1, a first raw ceramic layer 13 having a thickness of about 2 to 3 μm is formed on the first carrier film 11 by a coater such as a reverse roll coater. And further, on the first green ceramic layer 13,
As shown in FIG. 3, a metal paste layer 14 containing a metal to be an internal electrode is formed in a predetermined pattern by means such as screen printing or gravure printing. by this,
The first laminated body 15 is obtained. In FIG. 3, the first carrier film 11 and the first green ceramic layer 13
Both ends of the are shown cut away and two metal paste layers 14 are shown. This is intended to obtain a plurality of monolithic ceramic capacitors all at once by cutting them later. In the state shown in FIG. 3, the first green ceramic layer 13 may be swollen or dissolved by the solvent exuding from the metal paste layer 14. Further, at this stage, the solvent contained in the metal paste layer 14 is evaporated to such an extent that it does not adversely affect other ceramic layers in the subsequent steps.

On the other hand, the second green ceramic layer 16 is formed on the second carrier film 12, as shown in FIG. As a result, the second stacked body 17 is obtained. The second green ceramic layer 16 can be formed by a method similar to that of the first green ceramic layer 13, and the thickness thereof is about several μm, and preferably the first green ceramic layer 13 is smaller than the first green ceramic layer 13. Chosen thickly.

Next, the first green ceramic layer 13 and the second green ceramic layer
16 and 16 are overlapped with the metal paste layer 14 sandwiched therebetween.
At this time, the first or second green ceramic layer 13 or 16
One of the first or second green ceramic layers 13 or 16 is placed in the first position while the other is placed in the reference position.
Alternatively, while being held by the second carrier film 11 or 12, either one of the raw ceramic layers 13 or 16
A first crimping step of crimping onto is carried out. In this embodiment, as shown in FIG. 4, the first green ceramic layer 13 is placed at the reference position. First green ceramic layer 13
Is fixed on the reference member 18 which provides the reference position via the first carrier film 11. The reference member 18 is provided with, for example, a vacuum suction hole 19, by which the first laminated body 15 is fixed. The reference member 18 is the first laminated body 15
An adhesive tape, an ultraviolet curable resin film, or the like may be used instead of the vacuum suction hole 19 in order to fix the above.

As shown in FIG. 4, the second green ceramic layer 16 is
The second laminated body 17 held by the carrier film 12 is placed on the first green ceramic layer 13 via the metal paste layer 14. The first and second green ceramic layers 13 and 16 are thermocompression-bonded to each other via the metal paste layer 14 by the thermocompression-bonding member 21 having the heater 20 built therein.
The conditions for thermocompression bonding at this time are: pressure of 25 to 40 kg / cm ² ,
It has been confirmed by experiments that a temperature of 70 to 80 ° C. and a holding time of 5 seconds or more give good results.

When carrying out the crimping step shown in FIG. 4, the first and second laminated bodies 15 and 17 may be punched to have predetermined dimensions, respectively, or
The continuous sheet may be crimped and then punched to a predetermined size.

Next, a step of removing one of the first and second carrier films 11 and 12 from the first and second laminates 15 and 17 which are pressure-bonded to each other through the steps shown in FIG. 4 is performed. To be done. Carrier film 11 or
A removal method is typically applied to the removal of 12, and details thereof will be described later with reference to FIGS. 10 to 13, respectively. In this embodiment, as shown in FIG.
The first carrier film 11 contained in the laminated body 15 is removed. As a result, the first green ceramic layer 13, the metal paste layer 14, and the second green ceramic layer 16 are formed.
And a third laminate comprising the second carrier film 12
You get 22. At this time, the total thickness of the first green ceramic layer 13, the metal paste layer 14, and the second green ceramic layer 16 is, for example, about 5 to 10 μm.

Contrary to the case shown in FIG. 5, in the case of removing the second carrier film 12, after the pressure bonding step shown in FIG. The second carrier film 12 can be removed without removing the laminates 15 and 17.

Next, a second pressure bonding step is performed using a plurality of the third laminates 22 shown in FIG. This second crimping step is generally described by placing either the first or the second green ceramic layer 13 or 16 in the reference position while not sandwiching the metal paste layer 14. Either the first or second green ceramic layer 13 or 16 is held on the first or second carrier film 11 or 12 so that the green ceramic layer 13 and the second green ceramic layer 16 overlap. The raw ceramic layer of one of the above
It is to be crimped onto 13 or 16.
In this embodiment, as shown in FIG. 6, with the second green ceramic layer 16 placed in the reference position and the first green ceramic layer 13 held by the second carrier film 12,
This crimping step is performed.

At the stage shown in FIG. 6, steps other than the above-mentioned crimping step have already been completed. The third green laminate 22 shown in FIG.
The steps performed before the step of crimping to the base will be described. First, on the reference member 23 having the same structure as the reference member 18 shown in FIG. 4, the second member shown in FIG.
The laminated body 17 is fixedly placed. Then this second
The same second green ceramic layer 16 is further arranged on the second green ceramic layer 16 of the laminate 17. The latter second green ceramic layer 16 can be formed by pressing the second laminate 17 and then removing the second carrier film 12. Furthermore, a laminated structure 24 composed of the first green ceramic layer 13, the metal paste layer 14, and the second green ceramic layer 16 is formed thereon. The laminated structure 24 will be described in FIG. It has already been formed using the third stack 22 to which the crimping step is about to be applied.

In FIG. 6, the third laminated body 22 is placed on the uppermost second green ceramic layer 16 of the laminated structure 24 and thermocompression-bonded by the thermocompression-bonding member 25. The thermocompression bonding member 25 has substantially the same structure as the thermocompression bonding member 21 shown in FIG. 4, and the thermocompression bonding conditions are also substantially the same as in the case of FIG.

When the steps shown in FIG. 6 are completed, the state shown in FIG. 7 is obtained. Here, the second carrier film 12 holding the third laminate 22 is removed.

In FIG. 7, a plurality of dashed-dotted lines 26 extending in the vertical direction indicate cutting positions for forming individual monolithic ceramic capacitors, but they are located on different layers above and below the dashed-dotted line 26. As can be seen by looking at the positional relationship with the metal paste layer 14, the position of the metal paste layer 14 is
It must be tightly positioned during the crimping step shown in FIG. Such positioning can be easily performed by using a plurality of positioning posts 27 and 28 as shown in FIG. In FIG. 8, the plate member 29 located above corresponds to the third laminate 22 in FIG. 6, and the plate member 30 located below corresponds to the second laminate 17.
And the laminated structure 24. Therefore, since the plate members 29 and 30 each have the second carrier film 12 having a relatively high mechanical strength,
By bringing the end edges of the carrier film 12 into contact with the positioning posts 27 and 28, the plate-like members 29 and 30 can be reliably positioned with respect to each other.

The steps shown in FIGS. 6 and 7 are further repeated depending on the number of internal electrodes required for the monolithic ceramic capacitor to be obtained. Then, when the predetermined stacking is completed, the entire body is finally crimped.

It should be noted that, as can be seen by comparing the intervals between the plurality of alternate long and short dash lines 26 indicating the cut points and the intervals between the metal paste layers 14 which are vertically opposed to each other in FIG. In order to make it easy, the dimension in the thickness direction is exaggerated in the drawing.

After cutting at the location indicated by the alternate long and short dash line 26 in FIG. 7 to obtain an unfired chip for a laminated ceramic capacitor,
Similar to the conventional method for manufacturing a monolithic ceramic capacitor, it is subjected to a firing step, and then external electrodes are applied.
The step of removing the second carrier film 12 contained in the second laminate 17 shown in FIG. 7 may be performed before the cutting step or after the cutting step. .

FIG. 9 is a sectional view showing an example of the obtained monolithic ceramic capacitor. In FIG. 9, a plurality of first
Green ceramic layer 13 and a plurality of second green ceramic layers
Inside the ceramic dielectric 31 obtained from 16, a plurality of internal electrodes 32 are formed. These internal electrodes 32 are obtained from the metal paste layer 14. In addition, a pair of external electrodes 33 and 34 are provided on both end surfaces of the ceramic dielectric 31 so as to be connected to specific ones of the internal electrodes 32.
Are formed.

In the method of manufacturing a monolithic ceramic capacitor described above, for example, in the step shown in FIG. 4 or the step shown in FIG.
Removing 11 or 12 is done. Such removal of the carrier film 11 or 12 can be achieved, for example, by the methods shown in FIGS. 10 to 13, respectively. In FIGS. 10 to 13, numeral 35 indicates a carrier film to be removed. Further, an element indicated by an imaginary line and provided with "36" indicates an object on which the carrier film 35 is to be removed, and the object 36 is fixed on the fixing surface 37.

In FIG. 10, a vacuum suction chuck 38 is used, and the carrier film 35 is vacuum suction chucked by vacuum suction 39.
It is said that it will be joined to 38. Therefore, when the vacuum suction chuck 38 is pulled up, for example, in the direction shown by the arrow 40, the carrier film 35 is peeled from the object 36 by the vacuum suction chuck 38.

In FIG. 11, a flexible sheet 41 made of, for example, rubber, whose surface is tacky, is used. Sheet
41 adheres to the carrier film 35, and when this is pulled up in the direction shown by the arrow 42, for example, the carrier film 35
Is peeled from the object 36 with the sheet 41.

In FIG. 12, a roller 43 made of, for example, rubber having a peripheral surface provided with adhesiveness is used. This roller 43
By rolling on the carrier film 35 as shown by an arrow 44, the carrier film 35 is peeled from the object 36 in accordance with the rolling of the roller 43.

In FIG. 13, a plate 45 made of, for example, aluminum, acrylic resin or the like having a surface provided with adhesiveness is used. Board
45 is rotatably supported at its one end via a shaft 46. After adhering the carrier film 35 to the plate 45,
When the plate 45 is rotated as shown by the arrow 47, the carrier film 35 is peeled from the object 36 in response to this.

In the first embodiment of the present invention described above with reference to FIGS. 1 to 7, in particular, the first crimping step (fourth
(Figure) is carried out with both the first and second green ceramic layers 13 and 16 held on the first and second carrier films 11 and 12, respectively, after this first crimping step, A step of removing one or the second carrier film 11 or 12, eg the first carrier film 11, is carried out (FIG. 5) and a second crimping step (sixth).
The figure shows a raw ceramic layer 13 or 16 which was in contact with the removed carrier film 11 or 12, either of the first or second green ceramic layer 13 or 16, for example the first raw ceramic layer 13 Is overlaid on either the first or second green ceramic layer 13 or 16, on the other hand, for example the second green ceramic layer 16, and after this second crimping step the first or second carrier the film
A step of removing 11 or 12, eg the second carrier film 12, has been carried out (FIG. 7). However, the following embodiments are possible within the scope of the present invention. That is, the first and second crimping steps include the first
And the first and second laminates while alternately interposing the respective removal steps of the second carrier films 11 and 12.
It may be carried out with the step of stacking 15 and 17 alternately. This will be described with reference to FIGS. 14 to 16.

In FIG. 14, on the reference member 48, for example, three second green ceramic layers 16 are laminated. In this state,
The first stack 15 shown in FIG. 3 is pressed onto the uppermost second green ceramic layer 16. This achieves a first crimping step in which the first green ceramic layer 13 and the second green ceramic layer 16 are sandwiched by the metal paste layer 14 so as to overlap each other.

Then, the first carrier film 11 is removed.

Next, as shown in FIG. 15, the second laminated body 17 is pressure-bonded onto the first green ceramic layer 13. This achieves a second crimping step in which the first green ceramic layer 13 and the second green ceramic layer 16 are placed in an overlapping state without sandwiching the metal paste layer 14.

Then, the second carrier film 12 is removed.

Next, as shown in FIG. 16, the first laminated body 15 is again formed into the second laminated body 15.
Is crimped onto the green ceramic layer 16 and the first crimping step similar to that shown in FIG. 14 is repeated.

Thereafter, the steps shown in FIGS. 14 to 16 are repeated by a desired number. Subsequent cutting steps and the like are the same as those in the first embodiment, and the description thereof will be omitted.

[Brief description of drawings]

1 to 9 are views for explaining the first embodiment of the present invention. Here, in particular, FIG.
The first green ceramic layer 13 is formed on the first carrier film 11.
FIG. 2 is a cross-sectional view showing a state in which the
3 is a cross-sectional view showing a second laminate 17 in which a second green ceramic layer 16 is formed on the carrier film 12 of FIG.
The figure is a cross-sectional view showing a first laminate 15 in which a metal paste layer 14 is formed on the first green ceramic layer 13 shown in FIG. 1, and FIG. 4 is a first laminate. 15 and the second stack 17
FIG. 5 is a cross-sectional view showing a crimping step with and FIG.
It is sectional drawing which shows the 3rd laminated body 22 which remove | eliminated the 1st carrier film 11 from the structure obtained by the step of the figure, and FIG. 6 is the step which press-bonds the 3rd laminated body 22 one by one. FIG. 7 is a cross-sectional view showing the laminated body 22 of FIG.
FIG. 8 is a cross-sectional view showing a step of removing the second carrier film 12 after pressure bonding of FIG. 8, and FIG. 8 is a perspective view schematically showing a positioning method performed for positioning the metal paste layer 14. FIG. 9 is a sectional view showing the obtained monolithic ceramic capacitor. 10 to 13 show the carrier film 35, respectively.
Each of the methods for removing is schematically illustrated. 14 to 16 are views for explaining the second embodiment of the present invention. Here, in particular, FIG.
It is sectional drawing which shows the step of crimping | bonding the 1st laminated body 15, FIG. 15 is sectional drawing which shows the step of crimping | bonding the 2nd laminated body 17, and FIG. 16 was shown in FIG. It is sectional drawing which shows the step which further pressure-bonds the 1st laminated body 15 after a step. FIG. 17 is a sectional view showing a laminated state of the raw ceramic layer 1 and the metal paste layer 2 for explaining the drawbacks of the conventional technique. In the figure, 11 is a first carrier film, 12 is a second carrier film, 13 is a first green ceramic layer, 14 is a metal paste, 15 is a first laminate, 16 is a second green ceramic layer, Reference numeral 17 is a second laminated body, 18, 23 and 48 are reference members for giving reference positions, 21 and 25 are thermocompression bonding members, 31 is a ceramic dielectric, 32 is an internal electrode, 33 and 34 are external electrodes, 35 Is a carrier film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Takakura 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) Reference JP-A-57-139916 (JP, A) JP-A-61 -55909 (JP, A)

Claims (3)

[Claims] 1. Preparing first and second carrier films, forming a first green ceramic layer on the first carrier film, and further forming internal electrodes on the first green ceramic layer. A step of preparing a first laminate in which a metal paste layer containing a metal is formed in a predetermined pattern, and a solvent contained in the metal paste layer formed on the first green ceramic layer is mixed with another ceramic layer. Evaporating to such an extent that does not adversely affect the temperature, preparing a second laminate having a second green ceramic layer formed on the second carrier film, and the first or second green ceramic. While placing one of the layers at the reference position, the first green ceramic layer and the second green ceramic layer are sandwiched by the metal paste layer from which the solvent has been evaporated. Either one of the first and second green ceramic layers is held by the first or second carrier film so as to be overlapped with each other by using a thermocompression-bonding member containing a heater. A first pressure-bonding step of thermocompression-bonding onto one of the raw ceramic layers; and placing the metal paste layer without sandwiching the metal paste layer while placing one of the first and second raw ceramic layers at a reference position. One of the first or second raw ceramic layers is held by the first or second carrier film so that the one raw ceramic layer and the second raw ceramic layer overlap with each other. A second pressure-bonding step of performing heat-pressure-bonding on one of the raw ceramic layers using a heat-pressure bonding member having a built-in heater, and the first laminate to the first carrier film A first removal step of removing said second removal step of removing the second carrier film from the second laminate, wherein the steps are repeated, the method of production of a multilayer ceramic capacitor. 2. The first crimping step is performed with both the first and second green ceramic layers held by the first and second carrier films, respectively, and the first crimping step is performed. After the step, either one of the first or second removing step is performed, and the second crimping step is one of the first or second green ceramic layer and is removed. The green ceramic layer that was in contact with the carrier film is formed so as to overlap with the other of the first and second green ceramic layers, and after the second pressure bonding step, the first or second removal step is performed. The method for manufacturing a monolithic ceramic capacitor according to claim 1, wherein either of the other is performed. 3. The first and second crimping steps include a step of alternately stacking the first and second laminates while alternately interposing the first and second removing steps. A method of manufacturing a monolithic ceramic capacitor according to claim 1.