JP2000277382A - Multi-laminated ceramic capacitor and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable muti-laminated ceramic capacitor which has a large effective area for internal electrodes, is free of capacitance loss, and is superior in thermal shock resistance, and a method of manufacturing the same. SOLUTION: A multi-laminated ceramic capacitor is formed by alternately laminating an internal electrode layer 2, in which each internal electrode 2a is provided with a connecting part 4 at one of the edges of each internal electrode 2a and a dielectric ceramic layer 1 repeatedly to form a plurality of laminated layers which are sintered. In the sintered body, in which a plurality of capacitor elements are integrated side by side, pairs of outer electrodes 5 are formed on the opposed side surfaces, wherein the number of pairs corresponds to the number of the capacitor elements. The edge of each connecting part 4 is exposed on the respective opposed outer surface alternately on every other layer across each dielectric layer in the laminated direction, and the internal electrodes 2a are electrically connected to respective outer electrodes 5 via exposed edges of the connecting parts 4. Here, the widths of the inner electrodes 2a, connecting parts 4 and outer electrodes 5 are such that they satisfy those relation: inner electrode 2a > outer electrode 5 > connecting part 4, and the film thickness of the connecting parts 4 is larger than that of the internal electrodes 2a, and moreover the connecting boundary part between the inner electrode 2a and the connecting part 4 are constituted of circular arc shapes 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor used for various electronic devices and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the recent miniaturization of information communication devices such as computers and mobile phones, high-density mounting of electronic components has been progressing, and miniaturization and large capacity of multilayer ceramic capacitors have been desired. ing. In order to reduce the mounting area, a multi-layered multilayer ceramic capacitor in which a plurality of multilayer capacitors are juxtaposed in a single body is demanded from the market.

[0003] Conventional multi-layer monolithic ceramic capacitor 8
4 to 6, as shown in FIGS. 4 to 6, had a structure in which a plurality of internal electrode layers 2 and dielectric ceramic layers 1 having a width smaller than the width of the external electrode 5 and substantially uniform in the planar direction were alternately laminated. . The width of the external electrodes 5 is standardized in order to prevent a short circuit between adjacent external electrodes 5 due to soldering or the like when the multiple-layer ceramic capacitor 8 is mounted on a circuit board.

Hereinafter, a conventional multiple-layer ceramic capacitor 8 and a method of manufacturing the same will be described with reference to FIGS.

First, a slurry comprising a dielectric ceramic powder containing barium titanate as a main component and an organic binder or the like is applied on a carrier film by a doctor blade method and then dried to produce a green sheet of the dielectric ceramic layer 1. .

[0006] Next, a predetermined number of green sheets are repeatedly heated and laminated to produce three blocks of invalid layers.

Next, an electrode paste mainly composed of a metal powder such as palladium is screen-printed on the block surface of the ineffective layer 3 by screen printing or the like to form a plurality of internal electrode layers 2 on the same plane. The layer 2 is formed. Subsequently, a green sheet is laminated on the surface of the first internal electrode layer 2, and then the second internal electrode layer 2 is formed by printing. Further, after a green sheet is laminated on the surface of the second internal electrode layer 2, the third internal electrode layer 2 is formed by printing.

After a predetermined number of green sheets and internal electrode layers 2 are alternately laminated in this manner, finally, a block of an ineffective layer 3 is laminated to form a laminated green block (not shown) for a multi-layered multilayer ceramic capacitor. Is prepared. At this time,
The thickness of the internal electrode layer 2 is formed so as to be uniform in the plane direction, and the even-numbered internal electrode layer 2 has a predetermined length in the longitudinal direction of the printed internal electrode layer 2 with respect to the odd-numbered internal electrode layer 2. Printing is performed so that each of the green sheets is a pair with the green sheets shifted in dimension.

Thereafter, the green laminate is cut into predetermined dimensions and separated to produce a green chip of a multiple-layer ceramic capacitor 8 in which a plurality of capacitor elements are juxtaposed. The obtained green chip has a structure in which one end of the internal electrode layer 2 is provided for each capacitor element and one side of the green sheet of the dielectric ceramic layer 1 is alternately exposed on opposite side surfaces at equal intervals. Has become.

Next, after the green chip is degreased, it is fired at a predetermined temperature to produce a sintered body (not shown) of the multilayer ceramic capacitor 8.

Next, external electrodes 5 electrically connected to the internal electrode layers 2 are formed on the opposing side surfaces of the sintered body in which a plurality of capacitor elements are juxtaposed to expose the internal electrode layers 2 to the capacitor elements. Correspondingly, a plurality of pairs are provided to complete the multilayer ceramic capacitor 8.

[0012]

However, in the above-mentioned conventional method, when forming the external electrode 5 electrically connected to one end of the internal electrode layer 2 exposed on the opposite side surface of the sintered body, It is difficult to prevent a short circuit between the adjacent external electrodes 5 and to form the internal electrode layer 2 so as to cover the entire end of the exposed internal electrode layer 2. There was a problem that the product yield was reduced.

Further, as shown in FIG. 4, the effective area of the internal electrode layer 2 which is smaller than the width of the external electrode 5 becomes small, and when the number of laminated dielectric ceramic layers 1 is the same, the capacity of the capacitor element can be increased. Is disadvantageous. As a countermeasure, if the width of the internal electrode layer 2 is increased to increase the effective area,
The width of the external electrode 5 connected thereto becomes large, the interval between the external electrodes 5 of the adjacent capacitor elements becomes narrow, and there is a possibility that an electrical short circuit occurs. However, there is a problem that the workability is extremely reduced because the material protrudes from the external electrode 5.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a single element body in which a plurality of internal electrode layers and dielectric ceramic layers formed on the same plane are alternately laminated and fired. In a multiple-layer monolithic ceramic capacitor in which a plurality of pairs of external electrodes corresponding to capacitor elements are provided on opposing side surfaces of a sintered body in which a plurality of capacitor elements are juxtaposed, one end of the internal electrode layer is Along with being exposed on alternately facing side surfaces alternately with the dielectric ceramic layer interposed therebetween in the stacking direction, and at one end of the internal electrode,
A connection portion electrically connected to the external electrode is provided through the connection portion, and the width of the connection portion is smaller than the width of the internal electrode and the width of the external electrode, thereby improving workability and enhancing reliability. Is what you get.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of capacitors are formed by alternately laminating and firing a plurality of internal electrode layers and a dielectric ceramic layer formed on the same plane. In a multiple-layered multilayer ceramic capacitor in which a plurality of pairs of external electrodes corresponding to the number of the capacitor elements are provided on opposing side surfaces of a sintered body in which elements are juxtaposed in a single element body, the internal electrode layer is an internal electrode. A connection portion is provided at one end of the substrate, and the end portion of the connection portion is alternately exposed on the side opposite to each other alternately in the stacking direction with the dielectric ceramic layer interposed therebetween, and the internal electrode is connected via the connection portion. Is electrically connected to the external electrode, and the width of the connection portion is configured to be smaller than the width of the internal electrode and the width of the external electrode, and by providing a connection portion narrower than the width of the internal electrode and the external electrode. Of the internal electrode Even if the width of the external electrode is wider than the width of the internal electrode layer, forming the external electrode wider than the width of the connection part prevents the connection part from protruding, and also sets the distance between the external electrodes of adjacent capacitor elements. Has an effect that external electrodes that can prevent short circuit between each other can be easily formed.

According to a second aspect of the present invention, the width of the internal electrode is wider than the width of the external electrode.
Accordingly, even if the width of the internal electrode is wider than the width of the external electrode and the effective area is increased, the internal electrode is connected to the external electrode wider than the internal electrode through the connection portion smaller than the width of the internal electrode. Therefore, it is possible to easily form an external electrode that does not protrude the connection portion from the external electrode, and that can prevent a short circuit between adjacent external electrodes, and furthermore, establishes electrical continuity between the internal electrode and the external electrode. This has the function of increasing the capacity of the secured multilayer ceramic capacitor.

According to a third aspect of the present invention, the connection boundary between the internal electrode and the connection portion is formed in an arc shape, and the connection boundary between the internal electrode and the connection portion having different widths is formed in an arc shape. By doing so, it is possible to avoid concentration of thermal stress at the connection boundary when soldering the finished product to the circuit board, and to suppress the occurrence of cracks inside the sintered body due to thermal shock.

According to a fourth aspect of the present invention, the connection portion is formed to be thicker than the internal electrode.
By making the thickness of the connection part thicker than the thickness of the internal electrode, the cross-sectional area of the connection part becomes large, and even if the width of the connection part to be connected to the external electrode is made narrow, the connection between the two is ensured, and the loss of capacity can be prevented. It has an effect of reducing the contact resistance between the internal electrode and the external electrode.

According to a fifth aspect of the present invention, there is provided a screen printing plate in which a plurality of internal electrodes and a connection portion connected thereto are formed on the same plane. Alternatively, using a screen printing plate in which at least one of the emulsion thicknesses is changed, a plurality of internal electrode layers and a dielectric ceramic layer are formed by printing the connection portion thicker than the internal electrode portion, and the connection portion of the fired sintered body is exposed. Is a method of forming external electrodes electrically connected to the internal electrode layer via the connection portions on the opposite side surfaces, and the connection portions formed by this are reliably connected to the external electrodes, and the capacity loss is caused. This makes it possible to easily manufacture a multi-layer type multilayer ceramic capacitor having excellent performance, which prevents or reduces the contact resistance between the internal electrode and the external electrode.

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

FIG. 1 is a top view of a multilayer ceramic capacitor 7 according to an embodiment of the present invention, FIG. 2 is a side sectional view of the same, and FIG. 3 is a front view of the same. In the figure, 1 is a dielectric ceramic layer, 2 is an internal electrode layer, 2a is an internal electrode, 3 is an ineffective layer, 4 is a connection part, 5 is an external electrode, and 6 is a connection boundary between the internal electrode 2 and the connection part 4. The circle 7 indicates a multiple-layer ceramic capacitor.

First, a predetermined amount of dielectric ceramic powder containing barium titanate as a main component, an organic binder, a plasticizer, and an organic solvent are mixed to prepare a slurry. Next, a slurry is applied to the carrier film by a doctor blade method and then dried to produce a green sheet of the dielectric ceramic layer 1.

Next, a predetermined number of green sheets are laminated and heat-pressed to prepare three blocks of invalid layers. afterwards,
A first internal electrode layer in which a plurality of internal electrodes 2a and connection portions 4 are formed at one end thereof on the same plane by a screen printing method using an electrode paste containing palladium as a main component on the block surface of the ineffective layer 3. 2 is formed by printing. Subsequently, after laminating a green sheet on the surface of the first internal electrode layer 2, the second internal electrode layer 2 is formed by printing. Further, after a green sheet is laminated on the surface of the second internal electrode layer 2, the third internal electrode layer 2 is formed by printing.

After a predetermined number of green sheets and internal electrode layers 2 are alternately stacked in this way, three blocks of ineffective layers are finally stacked to produce a stacked green block (not shown) for a multiple ceramic capacitor. I do. At this time, as shown in Table 1, the screen printing plate has a width of the connecting portion 4 of 0.1.
50 mm, the width of the internal electrode 2a is 0.200, 0.500
mm or the thickness of the internal electrode 2a is 1.5 μm,
Of the internal electrode 2a and the connecting portion 4
Radius of curvature of the arc 6 at the boundary of the connection with 0, 0.025,
One having a thickness of 0.100 mm was used.

The internal electrodes 2a and the connection portions 4 were printed by using a screen printing plate in which the emulsion thickness was partially controlled. The even-numbered internal electrode layer 2 is different from the odd-numbered internal electrode layer 2 by the printed internal electrode layer 2.
Are printed so as to form a pair with the green sheets shifted by a predetermined dimension in the longitudinal direction.

[0026]

[Table 1]

Next, the green laminate is cut into predetermined dimensions.
A green chip of a multiple-layer ceramic capacitor 7 having four separated capacitor elements arranged in parallel is manufactured. In the obtained green chip, a plurality of connecting portions 4 connected to one end of the internal electrode layer 2 are alternately opposed to each other across the green sheet of the dielectric ceramic layer 1 for each capacitor element. The structure is exposed at equal intervals.

Next, the green chip is degreased and fired at a predetermined temperature to produce a sintered body (not shown) of the multilayer ceramic capacitor 7. Thereafter, four external electrodes 5 electrically connected to the internal electrodes 2a via the connection portions 4 are provided on opposite side surfaces where the connection portions 4 of the sintered body in which four capacitor elements are juxtaposed are exposed. In this case, four pairs were provided in correspondence with the above-mentioned capacitor elements to complete a multiple-layer ceramic capacitor 7 as shown in FIG.

The external dimensions of the quadruple-type multilayer ceramic capacitor manufactured in this embodiment are 3.2 × 1.6.
× External electrodes 5 having a height of 0.85 mm and a width of 0.4 mm were formed at opposing side surfaces where the connecting portions 4 were exposed, and external electrodes 5 having a width of 0.4 mm were formed at intervals of 0.4 mm.

Each of the manufactured multilayer ceramic capacitors 7 protrudes from the external electrode 5 of the connecting portion 4 and the external electrode 5 of the internal electrode layer 2 of the multilayer ceramic capacitor 8 manufactured by the conventional method. The defective formation rate of the protruding external electrode 5 and the effective area 10 of the internal electrode when the width of the internal electrode layer 2 of the conventional product is 0.200 mm
0, the effective area ratio of the internal electrodes according to the present embodiment, the rate of occurrence of cracks due to thermal shock during soldering, and the poor capacitance due to poor connection between the external electrodes 5 and the connection portions 4 and the internal electrode layer 2 Was evaluated, and the results are shown in Table 1 together.

As shown in Table 1, the product of the present invention has a very low rate of defective formation of the external electrode 5 due to the protrusion of the connection portion 4 as compared with the conventional product. In the present invention, the effective area of the internal electrode is 2.5 times that of the conventional product, and the capacitance is increased. Further, when the thickness of the connection portion 4 is set to 1.5 μm, which is the same as the thickness of the internal electrode 2a, the connection width between the external electrode 5 and the connection portion 4 becomes small, but thermal cracks and loss of capacitance can be reduced. Was. Further, the thickness of the connection part 4 is 2 μm.
It can be seen that the occurrence of the capacitance failure is extremely reduced, and that the cracks due to the thermal shock are completely eliminated by making the connection boundary between the internal electrode 2a and the connection portion 4 arc-shaped.

In this embodiment, the description has been given of the multi-layer type multilayer ceramic capacitor 7 in which four capacitor elements 3.2 × 1.6 and 0.85 mm in height are arranged in parallel. This is also effective for the external dimensions or the number of capacitor elements arranged in parallel. In addition, the emulsion thickness of the screen printing plate was controlled to provide a thickness difference between the internal electrode 2a and the connection portion 4. However, it is also possible to control the film thickness by changing the gauze thickness, the aperture ratio, and the like. Instead, another method such as intaglio printing can be used.

[0033]

As described above, the multi-layered multilayer ceramic capacitor and the method of manufacturing the same according to the present invention comprise a plurality of internal electrode layers formed on the same plane, an internal electrode layer having a connection formed at one end thereof, and a dielectric. Multiple layers alternately with body ceramic layers,
In a multi-layer monolithic ceramic capacitor in which a plurality of capacitor elements are juxtaposed in a single body and a plurality of pairs of external electrodes corresponding to the capacitor elements are provided on opposite sides of a sintered body, The end portions are alternately exposed on opposite side surfaces alternately with the dielectric ceramic layer interposed therebetween in the stacking direction, and the internal electrodes are electrically connected to the external electrodes via the exposed side surfaces.

At this time, according to the present invention, the width of each of the internal electrode, the connection portion, and the external electrode is set as internal electrode> external electrode> connection portion. This makes the width of the external electrode larger than the connection regardless of the width of the internal electrode, preventing the connection part from protruding and, when mounting the multilayer ceramic capacitor on the circuit board, the external electrode of the adjacent capacitor element Appropriate intervals are provided so as to prevent short circuit between them, and the formation thereof is very easy. Further, the internal electrode is not limited by the width of the external electrode, and the effective area can be increased in consideration of only the insulation distance between the internal electrodes of adjacent capacitor elements, so that the capacity can be increased. Further, by making the thickness of the connection part thicker than that of the internal electrode, the connection area of the internal electrode to the external electrode via the connection part is increased, and the reliability of the electrical connection is ensured and the capacity loss does not occur. Further, by forming the connection boundary between the internal electrode and the connection portion in an arc shape, it is possible to manufacture a multi-layer monolithic ceramic capacitor that is resistant to heat shock when soldering the finished product to a circuit board or the like. . As a result, it is easy to provide a highly reliable multi-layered ceramic capacitor having a plurality of large-capacity capacitor elements arranged in parallel, which is an industrially effective means.

[Brief description of the drawings]

FIG. 1 is a top view of a quadruple-type multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the same.

FIG. 3 is a front view of the same.

FIG. 4 is a top view of a conventional quadruple-type multilayer ceramic capacitor.

FIG. 5 is a sectional view

FIG. 6 is a front view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric ceramic layer 2 Internal electrode layer 2a Internal electrode 3 Invalid layer 4 Connection part 5 External electrode 6 Arc R formed in the connection boundary of internal electrode and connection part 7 Multi-layer type multilayer ceramic capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E082 AA01 AB03 BC33 BC36 BC38 CC03 EE04 EE12 EE16 EE23 EE35 FG06 FG26 FG27 FG46 FG54 GG10 HH43 JJ03 LL01 LL02 LL03 MM22 MM24

Claims (5)

[Claims] 1. A sintered body in which a plurality of internal electrode layers and a dielectric ceramic layer formed on the same plane are alternately laminated and fired, and a plurality of capacitor elements are juxtaposed in a single element body. In a multiple-layer monolithic ceramic capacitor in which a plurality of pairs of external electrodes corresponding to the number of the capacitor elements are provided on opposing side surfaces, the internal electrode layer has a connection portion at one end of the internal electrode, and the connection portion End portions are alternately exposed on opposite side surfaces alternately in the stacking direction with the dielectric ceramic layer interposed therebetween, and an internal electrode is electrically connected to the external electrode via a connection portion. A multiple monolithic ceramic capacitor having a width smaller than a width of the internal electrode and a width of the external electrode. 2. The multiple-layer ceramic capacitor according to claim 1, wherein the width of the internal electrode is wider than the width of the external electrode. 3. The multilayer ceramic capacitor according to claim 1, wherein a connection boundary between the internal electrode and the connection portion is formed in an arc shape. 4. The multilayer ceramic capacitor according to claim 1, wherein the thickness of the connecting portion is formed to be thicker than the thickness of the internal electrode. 5. A screen printing plate formed by a plurality of internal electrodes and a connection portion connected to the plurality of internal electrodes on the same plane, wherein the connection portion is replaced by at least one of the aperture ratio of the internal electrode portion, the gauze thickness or the emulsion thickness. Using a screen printing plate, a plurality of internal electrode layers and a dielectric ceramic layer were formed by printing the connection part thicker than the internal electrode part, and a connection part was formed on the opposing side surfaces where the connection part of the fired sintered pair was exposed. A method of manufacturing a multiple-layer ceramic capacitor, in which external electrodes electrically connected to internal electrode layers are formed via the external electrodes.