JP2000040634A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify the effective laminated area of a pair of inner electrodes for acquiring a required electrostatic capacity even if the printing precision in the width direction of the inner electrodes is deteriorate, by a method wherein the narrow width inner electrodes alternately laminated holding a ceramic layer are arranged in irregularly slid positions in the widthwise direction within both side range of the wide width inner electrodes. SOLUTION: Greensheets for ceramic layers 2 are laminated on the lower ineffective layers 3, and then the narrow width inner electrode 5 as the first layer are printed on the green sheets. Next, the greensheets are laminated on the inner electrodes layers 5 so as to print the widewidth inner electrodes 6 as the second layer paired with the first layer narrow width inner electrodes 5. In such a constitution, the greensheets, narrow width inner electrodes 5, ceramic layers 2, wide width inner electrodes 6 are alternately and successively laminated in a specific numbers and finally, after print-laminating the narrow width inner electrodes 5, upper ineffective layers 4 are pressure-laminated. At this time, the narrow width inner electrodes 5 are print-laminated in irregularly slid positions in the widthwise direction within the width dimensional range of the wide width inner electrodes 6.

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 (hereinafter referred to as a multilayer capacitor).

[0002]

2. Description of the Related Art A conventional method for manufacturing a multilayer capacitor will be described with reference to the drawings.

FIG. 6 is a perspective view of a green laminate of a conventional multilayer capacitor, FIG. 7 is a cross-sectional view thereof, FIG.
FIG. 9 is a perspective view of a sintered body, and FIG. 10 is a perspective view of a finished product.

[0004] First, a ceramic dielectric layer (hereinafter, referred to as a ceramic layer) 42 green sheet is manufactured by using a known multilayer capacitor manufacturing method.

Next, a plurality of green sheets formed of the ceramic layer 42 are laminated to form a lower ineffective layer 43 and an upper ineffective layer 44, respectively.

Next, a ceramic layer 42 green sheet is laminated on the lower ineffective layer 43 surface, and a first-layer internal electrode 45 is printed thereon. Subsequently, a ceramic layer 42 green sheet is laminated on the first-layer internal electrode 45, and a second-layer internal electrode 4 paired with the first-layer internal electrode 45 is formed thereon.
Print 5 In this way, the ceramic layer 42 green sheets and the internal electrodes 45 are sequentially laminated alternately in a predetermined layer, and finally the upper ineffective layer 44 is laminated and pressure laminated to produce a laminated green block (not shown). At this time, each of the internal electrodes 45 has the same rectangular shape, and the laminate green block is formed by a green laminate 41 shown in FIG.
When cut into a shape, one end portion on the short side of the internal electrode 45 is alternately placed every other layer so that it is exposed to different end surfaces facing each other of the green laminated body 41 so as to be exposed one by one in the longitudinal direction of the internal electrode 45. To print and stack.

[0007] Thereafter, the produced green block laminate is cut into a green laminate 41 shown in FIG.
Subsequently, firing is performed at a predetermined temperature to produce a sintered body 47 as shown in FIG.

[0008] Barrel polishing of the obtained sintered body 47,
After exposing a group of internal electrodes 45 formed inside the sintered body 47 to both end surfaces of the sintered body 47, an external electrode 48 is formed so as to cover the entire end face portion where the group of internal electrodes 45 is exposed. 1
A multilayer capacitor 49 as shown in FIG.

[0009]

However, when the printing accuracy of the internal electrodes 45 in the width direction is reduced as shown in FIG. 7, the pair of internal electrodes 45 facing each other with the ceramic layer 42 interposed therebetween has an effective overlapping area. The capacitance value becomes smaller than the design value, and the difference between the thickness of the portion where the internal electrode 45 is formed and the thickness of the portion where the electrode is not formed increases as the number of stacked internal electrodes 45 increases. There has been a problem that the outer shape of the aggregate is distorted and delamination of internal structural defects occurs.

The present invention solves the above-mentioned conventional problems. Even if the printing accuracy in the width direction of the internal electrodes is reduced, the effective overlapping area of the pair of internal electrodes is constant, and the capacitance is substantially as designed. It is an object of the present invention to provide a multilayer capacitor which can be obtained and can suppress occurrence of internal structural defects.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of forming a pair of wide internal electrodes and narrow internal electrodes and alternately laminating a plurality of layers with a ceramic layer interposed therebetween. By arranging irregularly in the width direction within the range of both sides of the wide internal electrode, even if the printing accuracy in the width direction of the internal electrode is reduced, a certain effective overlapping area is secured and almost as designed. Capacitance can be obtained. Furthermore, by displacing the narrow internal electrodes irregularly in the width direction of the multilayer capacitor, the overlapping portion of the internal electrode group is dispersed in the width direction of the multilayer capacitor, and the difference in thickness between the portion where the internal electrode group is formed and the portion where the internal electrode group is not formed. And the deformation of the multilayer capacitor after sintering and the occurrence of delamination can be suppressed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a plurality of internal electrodes and ceramic layers are alternately laminated inside a body, and one end of the internal electrode is sandwiched between ceramic layers. Alternately, in a multilayer capacitor that is exposed to different end faces facing the element body and external electrodes are formed so as to be electrically connected to ends of the internal electrode layers exposed at both end faces, the internal electrodes sandwich the ceramic layer. A wide internal electrode and a narrow internal electrode, which are alternately laminated in the above manner, wherein the wide internal electrode is exposed on one end face of the element body and the narrow internal electrode is exposed on the other end face facing the laminate. A method for manufacturing a capacitor, wherein even if the printing accuracy in the width direction of the internal electrode group is reduced, the effective width between a pair of wide internal electrodes and a narrow internal electrode stacked so as to face each other with a ceramic layer interposed therebetween. Constant overlapping area It becomes possible, and has the effect that it is possible to obtain a multilayer capacitor having a capacitance as designed for.

According to a second aspect of the present invention, the narrow internal electrodes are irregularly displaced in the width direction of the multilayer capacitor within a range not protruding from both sides of the wide internal electrodes. The method for manufacturing a multilayer capacitor according to claim 1, wherein even if the printing accuracy of the internal electrode group in the width direction is reduced, a pair of wide capacitors stacked so as to face each other with the ceramic layer interposed therebetween. The effective overlapping area between the internal electrode and the narrow internal electrode can be kept constant, the capacitance can be obtained as designed, and the thickness difference between the internal electrode group forming part and the non-forming part is small. In other words, it has an effect that deformation and delamination of the multilayer capacitor after sintering can be suppressed.

According to a third aspect of the present invention, there is provided the method of manufacturing a multilayer capacitor according to the first or second aspect, wherein the narrow internal electrodes are arranged in an outer layer than the wide internal electrodes. Therefore, since the narrow internal electrodes are always arranged on the side near the upper and lower ineffective layers of the element body which is easily polished by barrel polishing after sintering, even if the internal electrodes are narrower, one of the outermost layers Can be reliably exposed to the end face of the element body, and has the effect of ensuring electrical connection with external electrodes.

According to a fourth aspect of the present invention, the thickness of the ineffective layer outside the narrow inner electrode in the outermost layer is made larger than the effective layer sandwiched between the wide internal electrode and the narrow internal electrode. 4. The method for manufacturing a multilayer ceramic capacitor according to claim 3, wherein the ineffective layer is thicker than the effective layer, so that a withstand voltage breakdown when a high voltage is applied between external electrodes of the multilayer capacitor. Has an effect that it always occurs between the effective layers having a short insulation distance and can prevent a decrease in the breakdown voltage.

The invention according to claim 5 of the present invention is characterized in that the width between the side of the wide internal electrode and the side surface of the element body is made larger than the thickness of the effective layer sandwiched between the wide internal electrode and the narrow internal electrode. The method for manufacturing a multilayer ceramic capacitor according to any one of claims 1 to 4, wherein a distance from a side of the wide internal electrode of the multilayer capacitor to a side surface of the element body is large. The withstand voltage breakdown when a high voltage is applied between the external electrodes of the capacitor always occurs between effective layers having a short insulation distance, and has an effect of preventing a decrease in the withstand voltage breakdown voltage.

(Embodiment) FIGS. 1 to 5 show a multilayer capacitor according to an embodiment of the present invention. 1 is a perspective view of a green laminate, FIG. 2 is a cross-sectional view of the green laminate, FIG. 3 is a development view of the green laminate, FIG. 4 is a perspective view of a sintered body, and FIG.
Is a perspective view of the finished product. 1 to 5, 1 is a green laminate, 2 is a ceramic layer, 3 is a lower ineffective layer, 4
Is the upper inactive layer, 5 is the narrow internal electrode, 6 is the wide internal electrode,
7 is a sintered body, 8 is an external electrode, and 9 is a finished product (multilayer capacitor).

First, a green sheet for the ceramic layer 2 is prepared from a slurry in which a ceramic dielectric powder, a binder, and a plasticizer are mixed and dispersed by a reverse roll molding method.

A plurality of green sheets for the ceramic layer 2 are laminated to form a lower ineffective layer 3 and an upper ineffective layer 4, respectively.

Next, a green sheet for the ceramic layer 2 is laminated on the lower ineffective layer 3, and a first-layer narrow internal electrode 5 is printed thereon as shown in FIG. Subsequently, a green sheet for the ceramic layer 2 is laminated on the first five narrow internal polarization layers, and a second wide electrode paired with the first narrow internal electrode 5 is formed thereon. The internal electrodes 6 are printed. In this manner, a predetermined number of the green sheets for the ceramic layer 2, the narrow internal electrodes 5, the ceramic layer 2, and the wide internal electrodes 6 are alternately laminated in order, and finally the narrow internal electrodes 5 are printed and laminated. The layers 4 are stacked and laminated under pressure to produce a laminate green block (not shown). At this time, as shown in FIG. 2, the narrow internal electrodes 5 are printed and laminated while being shifted irregularly in the width direction within the width dimension of the wide internal electrodes 6, so that the narrow internal electrodes 5 and the wide internal electrodes 6 have a wide width. Even if the printing accuracy in the direction decreases, the effective overlapping area does not become constant and small, and the capacitance as designed can be easily obtained. Further, the lowermost and uppermost narrow internal electrodes 5 are replaced with the wide internal electrodes 6.
Since it is disposed on the side closer to the lower ineffective layer 3 and the upper ineffective layer 4, that is, on the side that is easily polished by barrel polishing, the end of the narrowest internal electrode 5 in the outermost layer is surely placed on one side of the sintered body 7. At the end face of the sintered body 7, and the external electrode 8 formed on the end face of the sintered body 7 is reliably conducted, so that the capacitance as designed can be easily obtained.

The thickness of the lower invalid layer 3 and the upper invalid layer 4;
And the width from the side of the wide internal electrode 6 to the side of the sintered body 7
Since the thickness is larger than the thickness of the ceramic layer 2, the breakdown voltage breakdown when an abnormally high voltage is applied between the external electrodes 8 always occurs between the ceramic layers 2 having a short insulation distance, and the breakdown voltage breakdown voltage is reduced. I try to prevent it.

Next, the formed green laminate is cut into a predetermined shape to obtain a green laminate 1 shown in FIG.

Thereafter, the green laminate 1 is fired at a predetermined temperature to produce a sintered body 7 shown in FIG.

Next, barrel polishing of the sintered body 7 is performed, and one end of the narrow internal electrode 5 and the wide internal electrode 6 group formed inside the sintered body 7 Then, an external electrode 8 was formed so as to cover the entire end of the sintered body 7 to complete a multilayer capacitor 9 as shown in FIG.

The three lots of the multilayer capacitor 9 of the present embodiment thus manufactured and the conventional multilayer capacitor 4
9 lots, each 100 pieces / lot, 20 ° C
In room temperature, measurement frequency 1MHz, measurement voltage 1Vrms
The capacitance was measured by using the method shown in FIG. Note that the electrical characteristics of the sample multilayer capacitor are such that the nominal capacitance is 2.0
pF, capacitance tolerance ± 0.25 pF, CH characteristics, dimensions are 2.0 mm long × 1.25 mm wide × 0.65 mm thick, and the wide internal electrode 6 formed inside is 1.25 mm long × Width 0.
45 mm, narrow internal electrode 5 is 1.25 mm long x 0.15 width
mmm.

As shown in FIG. 11, the capacitance of the multilayer capacitor according to the embodiment of the present invention is very close to the design value of 2.0 pF as shown in (d) to (f), and the standard deviation σ is 0. Whereas the conventional product has a 3-5% smaller capacitance value than the design value as shown in (a)-(c), and a standard deviation σ of 0.077-0.096.
And has become larger. From this result, as in the embodiment of the present invention, the wide internal electrodes 6 and the narrow internal electrodes 5 are alternately laminated in a plurality of layers with the ceramic layer 2 interposed therebetween.
Is irregularly shifted in the width direction of the sintered body 7 within the width dimension of the wide internal electrode 6 and printed and laminated, so that even if the printing accuracy in the width direction of the narrow internal electrode 5 and the wide internal electrode 6 decreases, In addition, the effective overlapping area between the electrodes becomes constant, the capacitance according to the design value is obtained, the distortion of the outer shape of the sintered body 7 is reduced, and the occurrence of delamination of internal structural defects can be suppressed. It is an industrially effective means.

[0027]

As described above, according to the present invention, the internal electrodes of the multilayer capacitor are formed of two types, a wide internal electrode and a narrow internal electrode, and the two types of internal electrodes are vertically stacked with a ceramic layer interposed therebetween. Accordingly, even if the printing precision in the width direction of the internal electrode is reduced, a capacitance almost as designed can be obtained, and a multilayer capacitor with reduced external distortion of the sintered body and suppression of delamination is provided. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a perspective view of a green laminate of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the green laminate taken along line AA.

FIG. 3 is a development view of the green laminate.

FIG. 4 is a perspective view of the same sintered body.

FIG. 5 is a perspective view of the completed product.

FIG. 6 is a perspective view of a green laminate of a conventional multilayer ceramic capacitor.

FIG. 7 is a sectional view of the green laminate taken along line BB.

FIG. 8 is a development view of the green laminate.

FIG. 9 is a perspective view of the same sintered body.

FIG. 10 is a perspective view of the finished product.

FIGS. 11A to 11F are diagrams showing capacitance distributions of a product according to the embodiment of the present invention and a conventional product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Green laminated body 2 Ceramic dielectric layer 3 Lower ineffective layer 4 Upper ineffective layer 5 Narrow internal electrode 6 Wide internal electrode 7 Sintered body 8 External electrode 9 Multilayer capacitor

Claims (5)

[Claims] An internal electrode and a ceramic dielectric layer are alternately laminated in a plurality of layers inside a body, and one end of the internal electrode is alternately arranged with the ceramic dielectric layer interposed therebetween so as to be alternately arranged. In a multilayer ceramic capacitor in which external electrodes are formed so as to be exposed to different end faces facing each other and electrically connected to ends of the internal electrode layers exposed to the both end faces, the internal electrode layers are sandwiched between ceramic dielectric layers. A multilayer ceramic comprising a wide internal electrode and a narrow internal electrode alternately laminated, wherein the wide internal electrode is exposed on one end face of the element body and the narrow internal electrode is exposed on the other end face opposite to the ceramic body. Manufacturing method of capacitor. 2. The device according to claim 1, wherein the narrow internal electrodes are irregularly shifted in the width direction of the multilayer ceramic capacitor within a range not protruding from both sides of the wide internal electrodes. Manufacturing method of multilayer ceramic capacitor. 3. The method according to claim 1, wherein the narrow internal electrode layer is disposed outside the wide internal electrode layer.
3. The method for manufacturing a multilayer ceramic capacitor according to item 1. 4. The method according to claim 3, wherein the thickness of the ineffective layer outside the narrowest internal electrode of the outermost layer is larger than that of the effective layer sandwiched between the wide internal electrode and the narrow internal electrode. Manufacturing method of multilayer ceramic capacitor. 5. The method according to claim 1, wherein a width between a side of the wide internal electrode and a side surface of the element body is larger than a thickness of an effective layer sandwiched between the wide internal electrode and the narrow internal electrode. The method for manufacturing a multilayer ceramic capacitor according to any one of the above.