JP2000106323A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To substantially make uniform a film thickness of an internal electrode to ensure continuity by a method wherein the internal electrode is printed by use of a thin resist plate film at lamination initial stage of the internal electrode and by use of a thick resist plate film from a lamination middle stage. SOLUTION: A ceramic green sheet 1 is overlaid on a printing face of an internal electrode 2, and half pressurization is made at a predetermined pressurizing force, then it is slid by a predetermined length in the longitudinal direction of the internal electrode 2 with respect to the internal electrode 2 of a first layer to carry out printing for the internal electrode 2 of a second layer. Thereafter, it is dried at a temperature of 120 deg.C. Thus, the ceramic green sheet 1 is laminated and the internal electrode 2 is printed to be dried, repeatedly, and the ceramic green sheet 1 and the internal electrode 2 are respectively laminated in 30 layers. Thereafter, by use of a resist plate film 3 of the internal electrode 2, the thickness of the resist plate film 3 is changed, and the laminations of 10 layers are repeated, respectively. Finally, an upper invalid layer sheet is overlaid, and the entirety is pressurized at a predetermined pressing force to manufacture a laminated body.

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 A conventional method for manufacturing a multilayer ceramic capacitor will be described below.

FIG. 3 is an enlarged sectional view showing a printing state of the internal electrodes 2 in the latter half stage when the internal electrodes 2 are multi-layered.
FIG. 4 is a plan view showing a state in which an internal electrode 2 containing palladium as a main component is printed on the surface of the ceramic green sheet 1, and FIG. 5 is a sectional view of the multilayer ceramic capacitor. FIG.
5, reference numeral 3 denotes a resist plate film, 4 denotes a printing screen, 5 denotes an electrode paste, 6 denotes a cutting position, 7 denotes a ceramic layer, 8 denotes a sintered body, 9 denotes an ineffective layer, and 10 denotes an external electrode.

First, a binder, an organic solvent, and a plasticizer are added to a material powder containing barium titanate as a main component to form a slurry, and then a ceramic green sheet 1 having a predetermined thickness is produced by a known blade method.

Next, a predetermined number of the ceramic green sheets 1 are laminated to produce a sheet for the upper and lower ineffective layers 9.
Next, the ceramic green sheet 1 is overlaid on the surface of the lower inactive layer 9 sheet, the internal electrodes 2 are printed on the surface, and drying is performed. Subsequently, the next ceramic green sheet 1 is overlaid on the printing surface of the internal electrode 2 and pressed and pressed, and then the internal electrode 2 is printed and dried on the surface. In this way, the ceramic green sheet 1 is pressed and pressed and the internal electrode 2 is repeatedly printed and dried a predetermined number of times, and finally, the sheet for the upper ineffective layer 9 is laminated and pressed to form a laminate (not shown). Is prepared. still,
The thickness of the printing resist plate film 3 of the internal electrode 2 is one type, and the ceramic green sheets 1 on which the internal electrode 2 is printed are alternately shifted by a predetermined size in the longitudinal direction of the internal electrode 2 alternately. Lamination is performed.

Next, the laminate is cut into green chip (not shown) shapes of the multilayer ceramic capacitor along a cutting position 6 shown in FIG. The cut green chips have a configuration in which the internal electrodes 2 are alternately exposed on the opposite end faces in the longitudinal direction with the ceramic green sheets 1 interposed therebetween.

After that, the green chip is fired at a temperature of 1300 ° C. or more, and an external electrode 10 is formed on the exposed end face of the sintered body 8 so as to be electrically connected to the internal electrode 2. A method of obtaining a multilayer ceramic capacitor as shown in FIG. 5 has been general.

[0008]

However, in the above-described conventional method for manufacturing a multilayer ceramic capacitor, as the number of laminated ceramic green sheets 1 and internal electrodes 2 increases, the overlapping portion of the printed internal electrodes 2 is shown in FIG. As shown, the printed surface of the internal electrode 2 becomes convex. For this reason, the central part in the longitudinal direction of the printed internal electrode 2 becomes thin. If this continues further, eventually
There is a problem that the central part of the printed internal electrode 2 becomes extremely thin and the continuity deteriorates.

The present invention has been made to solve the above-mentioned problems, and has a multilayer ceramic capacitor in which the thickness of the internal electrodes is substantially uniform and the continuity can be ensured even in the case of multiple lamination of ceramic green sheets and internal electrodes. It is intended to provide a manufacturing method.

[0010]

In order to solve the above-mentioned problems, the present invention provides a method of forming a multilayer ceramic capacitor by laminating a plurality of ceramic green sheets and internal electrodes alternately. In the initial stage of lamination, a resist plate film having a small thickness is used, and printing of internal electrodes is performed using a thick resist plate film in the middle of lamination.

According to this method, even if the number of layers is increased, the central portion of the internal electrode is thinned, so that the electrode can be prevented from being cut.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is characterized in that, in the step of laminating a multilayer body of a multilayer ceramic capacitor formed by alternately laminating a plurality of ceramic green sheets and internal electrodes, The initial stage of lamination is a method of manufacturing a multilayer ceramic capacitor in which a thin resist plate film is used, and an internal electrode is printed using a thick resist plate film in the middle of lamination. As a result, even when the number of stacked ceramic green sheets and internal electrodes increases, the central portion in the longitudinal direction of the internal electrodes is prevented from becoming thin even on the convex surface of the overlapping portion of the internal electrodes. Has an effect that the thickness of the film can be maintained at a required thickness.

According to a second aspect of the present invention, there is provided the method for manufacturing a multilayer ceramic capacitor according to the first aspect, wherein the thickness of the internal electrode is in the range of 2 to 4 μm. This is because even if the metal component of the internal electrode is sintered during the next firing process, the continuity of the internal electrode is maintained without electrode breakage, and the thermal expansion and contraction reaction affects the sintering of the ceramic green sheet. The thickness does not affect the thickness.

According to a third aspect of the present invention, the viscosity of the electrode paste for an internal electrode is from 10,000 to 30,000.
2. The method for manufacturing a multilayer ceramic capacitor according to claim 1, wherein the range is 00 cps. This stipulates the viscosity of the electrode paste that can print the internal electrodes with a thickness of 2 to 4 μm with high accuracy.

An embodiment of the present invention will be described below. (Embodiment 1) FIG. 1 is an enlarged sectional view showing a printing state of an internal electrode 2 at an initial stage of lamination in an embodiment of a method of manufacturing a multilayer ceramic capacitor according to the present invention, and FIG. FIG. 4 is an enlarged cross-sectional view showing a state in which the thickness of the resist plate film 3 is changed and printing is performed in a state where the number of layers of the electrodes 2 is increased.

The structure of the multilayer ceramic capacitor is the same as that described in the conventional example. Since the same members are used in the manufacturing method as in the conventional example, the same reference numerals are used in the drawings, and the same parts are omitted in the description. .

First, 2 was prepared by the same means as the conventional method.
Ten ceramic green sheets 1 each having a thickness of 5 μm are laminated and pressed to form a sheet for the upper and lower ineffective layers 9.

Next, the ceramic green sheet 1 is superimposed on the sheet surface for the lower ineffective layer 9, and the inner electrode 2 of the first layer is 0.55 mm wide and 3.20 mm long as shown in FIG.
An internal electrode 2 having an interval between adjacent internal electrodes 2 of 0.38 mm in the width direction and 0.52 mm in the length direction is connected to the resist plate film 3 having a thickness of 10 mm.
After printing with an electrode paste 5 containing palladium as a main component using μm, drying is performed at a temperature of 120 ° C.

Next, the ceramic green sheet 1 is superimposed on the printed surface of the internal electrode 2 and a temporary pressurization is performed with a pressing force of 200 kg / cm ^2. After printing the internal electrode 2 of the second layer by shifting it by 0.93 mm in the direction, drying is performed at a temperature of 120 ° C.
In this manner, the lamination of the ceramic green sheets 1, the temporary pressurization, the printing of the third-layer internal electrodes 2 immediately above the printed portion of the first-layer internal electrodes 2, and the lamination of the ceramic green sheets 1 are sequentially performed. , Temporary pressurization, printing and drying of the fourth-layer internal electrode 2 directly above the printed portion of the second-layer internal electrode 2, alternately lamination of the ceramic green sheets 1, printing and drying of the internal electrode 2 are repeated. , Ceramic green sheet 1 and internal electrode 2
Are respectively laminated in 30 layers. At this time, the internal electrode 2 of the 30th layer is close to the state shown in FIG.

After that, as shown in FIG. 2, the thickness of the resist plate film 3 of the internal electrode 2 was changed to 15 μm, and ten layers were repeated in the same manner as described above. Then, the whole is fully pressurized at a pressure of 400 kg / cm ² for one minute to produce a laminate (not shown). The obtained laminate was cut along a cutting position 6 shown in FIG. 4 into a green chip (not shown) having a length of 1.86 mm, a width of 0.93 mm, and 40 layers of the internal electrodes 2. At this time, the green chip has a configuration in which the internal electrodes 2 are alternately exposed on the end faces in the longitudinal direction with the ceramic green sheet 1 interposed therebetween.

Next, the green chips are placed in a high-purity alumina sheath to which zirconia powder is sprayed, and the green chips are placed in an air atmosphere.
The sintered body 8 is produced by firing at a temperature of 300 ° C. for 2 hours.

Next, after polishing the end surface of the sintered body 8 where the internal electrode 2 is exposed, an indium-gallium alloy is applied as an external electrode 10 so as to be electrically connected to the internal electrode 2, as shown in FIG. Such a multilayer ceramic capacitor was completed. As a comparative example, the thickness of the resist plate film 3 was 1
Using only 0 μm, a multilayer ceramic capacitor of a conventional method in which 40 layers each of the ceramic green sheet 1 and the internal electrode 2 were laminated was also manufactured.

The capacitance of each of the 50 obtained multilayer ceramic capacitors was measured, and the results are shown in Table 1.

[0024]

[Table 1]

As shown in Table 1, the multilayer ceramic capacitor of the present invention in which the thickness of the resist plate film 3 is changed during the lamination process has a small variation with respect to the rated capacitance of 1000 ± 50 pF, while the conventional capacitor has a small variation. It can be seen that 12 defective ceramic capacitors of 950 pF or less are generated in the multilayer ceramic capacitor of the method. This is because the continuity of the internal electrode 2 is maintained by increasing the thickness of the resist plate film 3 of the internal electrode 2 of the present invention to 15 μm from the middle, and cuts due to sintering of the internal electrode 2 during the sintering process of the multilayer ceramic capacitor. Is prevented.

In order to confirm this, the defect of the conventional product was polished and the continuity of the internal electrode 2 was confirmed. As a result, a cut occurred at the center of the internal electrode 2 on one surface side of the sintered body 8. Was observed. From this, as shown in FIG.
When the number of laminations of the ceramic green sheets 1 and the internal electrodes 2 increases, it becomes clear that the overlapping convex portions of the internal electrodes 2 hinder the continuity of the printed internal electrodes 2.

In the first embodiment, two kinds of thicknesses of the resist plate film 3 are used. However, when the number of layers is further increased, it is necessary to further increase the types of the resist plate film 3 as necessary. On the other hand, if the thickness of the resist plate film 3 is 15 μm or more, the difference in thickness between the portion where the internal electrode 2 is formed and the portion where the internal electrode 2 is not formed becomes large, and the adhesiveness between the ceramic green sheets 1 is reduced by the main pressure, which is not preferable.

(Embodiment 2) As in Embodiment 1,
As shown in (Table 2), a ceramic green sheet 1 having a thickness of 25 μm was used, and up to 30 layers of the internal electrodes 2 were laminated.
The thickness of the resist plate film 3 is 4, 6, 10, 15 μm, whereas the thickness of the resist plate film 3 is 6, 10, 15, 20 μm for 31 to 40 layers.
The multi-layer ceramic capacitor was manufactured in the same manner as in the first embodiment by combining the m resist plate films 3 and the evaluation of the obtained multi-layer ceramic capacitor was shown in (Table 2).

In the second embodiment, the electrode paste 5 having a viscosity of 25,000 cps is used.
The thickness of the central portion of the printed internal electrode 2 after drying was 4, 6, 10, 15, 20 μm,
It was adjusted to be 4, 5, 7 μm.

[0030]

[Table 2]

As shown in Table 2, at the initial stage of lamination, the thickness of the internal electrode 2 was 1 μm (the thickness of the resist plate film 3 was 4 μm).
m), when the combination of the thickness of the internal electrode 2 is 2 μm (the thickness of the resist plate film 3 is 6 μm), the capacitance is 950 pF.
The following 40 defective products were detected. On the other hand, at the initial stage of lamination, the thickness of the internal electrode 2 is 5 μm (the thickness of the resist plate film 3 is 1 μm).
In the case of a combination of 5 μm) and 7 μm in thickness of the internal electrode 2 (20 μm in thickness of the resist plate film 3) from the middle, 13 delaminations occur although the capacitance is within the rated range.

On the other hand, in the other combinations, it can be seen that the capacitance is within the rated capacity range and that no delamination failure occurs. This means that if the thickness of the internal electrode 2 is less than 1 μm, electrode breakage will occur even in the initial lamination, and if the internal electrode 2 is made thicker than necessary, the adhesion between the ceramic green sheets 1 will decrease. This indicates that delamination may occur.

Therefore, in the initial stage of lamination, the thickness of the internal electrode 2 is controlled to 2 to 4 μm, and
It is clear that by controlling the thickness of the substrate from 4 to 5 μm, it is possible to prevent the occurrence of defective capacitance and delamination. When the thickness of all the internal electrodes 2 is 4 μm, the number of occurrences decreases, but delamination failure is confirmed.

(Embodiment 3) As in Embodiment 1,
A ceramic green sheet 1 having a thickness of 25 μm was used. The thickness of the resist plate film 3 was 10 μm for up to 30 layers of the internal electrodes 2, and the thickness of the resist plate film 3 was 15 μm for 31 to 40 layers. As shown in Table 3, the viscosity of Sample No. 5 was 8,000 to 35,000 cps, and the other conditions were the same as in Embodiment 1 to produce a multilayer ceramic capacitor. The obtained multilayer ceramic capacitor was evaluated in the same manner as in Embodiment 1, and the results are shown in (Table 3).

[0035]

[Table 3]

As shown in Table 3, the viscosity of the electrode paste 5 of the present invention was from 10,000 to 30,000 cps.
, The capacitance values are all within the rated range, while the viscosity is 8,000 or 35,000.
At 0 cps, there are 25 defects of 950 pF or less,
Alternatively, eleven are generated, and the variation in the capacitance is large.

Incidentally, these defective capacitors were polished, and the condition of the internal electrodes 2 was observed. When the viscosity is 8,000 cps, the amount of the electrode metal component decreases, and up to 30 layers of internal electrodes 2 using a 10 μm resist plate film 3 are cut off, resulting in 35.0%
In the case of 00 cps, the viscosity is too high, and it is considered that the electrode paste 5 is hardly removed from the mesh of the printing screen 4, and the printing is partially blurred.

From the above results, the viscosity of the electrode paste 5 is 1
It is clear that by controlling the range from 000 to 30,000 cps, variation in capacitance is small and continuity of the internal electrode 2 can be ensured.

[0039]

As described above, according to the present invention, in the step of laminating a multilayer body of a multilayer ceramic capacitor formed by alternately laminating a plurality of ceramic green sheets and internal electrodes,
The initial stage of lamination of internal electrodes is performed using a thin resist plate film, and printing is performed from the middle of lamination using a thick resist plate film.The internal electrodes of the same laminate are printed using a resist plate of at least two or more thicknesses. If necessary, the viscosity of the internal electrode paste is controlled in the range of 10,000 to 30,000 cps, so that the variation of the capacitance is small and the continuity of the internal electrode is ensured.
It is possible to provide a multilayer ceramic capacitor having excellent performance in which occurrence of delamination failure is suppressed.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a printed state of internal electrodes in an initial stage of lamination in one embodiment of a method for manufacturing a multilayer ceramic capacitor of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a state in which a resist plate film is changed from the middle of the lamination and an internal electrode is printed.

FIG. 3 is an enlarged cross-sectional view showing a printing state of an internal electrode in the middle of lamination of a conventional multi-laminate.

FIG. 4 is a plan view showing a state where internal electrodes are printed on a ceramic green sheet surface.

FIG. 5 is a sectional view of a multilayer ceramic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic green sheet 2 Internal electrode 3 Resist plate film 4 Printing screen 5 Electrode paste 6 Cutting position 7 Ceramic layer 8 Sintered body 9 Invalid layer 10 External electrode

Claims (3)

[Claims] In a laminating step of a multilayer ceramic capacitor formed by alternately laminating a plurality of ceramic green sheets and internal electrodes, an initial stage of laminating the internal electrodes uses a thin resist plate film, Of manufacturing a multilayer ceramic capacitor in which internal electrodes are printed using a thick resist plate film. 2. The method according to claim 1, wherein the thickness of the internal electrode is in a range of 2 to 4 μm. 3. The viscosity of the electrode paste for an internal electrode is 10,
2. The method for manufacturing a multilayer ceramic capacitor according to claim 1, wherein the range is from 000 to 30,000 cps.