JPH0645181A - Multilayer ceramic capacitor - Google Patents

Abstract

PURPOSE:To enable a multilayer ceramic capacitor to be specified in manufacturing date and lot when malfunction detection and failure analysis are executed by a method wherein one or a specific number of inner electrode layers are exposed out of the side face of a sintered body adjacent to an outer electrode lead-out part. CONSTITUTION:An inner electrode 41 is provided, where at least one or a specific number of inner electrode layers 4 are exposed out of the side face of a sintered body adjacent to an outer electrode 5 lead-out part. An indication of lot can be made to correspond easily to manufacturing months January to December by increasing inner electrodes in number of layers exposed at the side face for indicating lot No. By this setup, a ceramic capacitor of this design can be specified in manufacturing lot when malfunction detection and failure analysis are executed and easily lessened in size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated ceramic capacitor, and more particularly to the structure of its internal electrodes.

[0002]

2. Description of the Related Art Conventionally, a laminated ceramic capacitor is shown in FIG.
As shown in, the ceramic dielectrics 3 and the internal electrodes 4 are alternately stacked to form a capacitor.

In this monolithic ceramic capacitor, by reducing the thickness of the ceramic dielectric, increasing the number of laminated layers, and further increasing the relative permittivity of the ceramic dielectric, the miniaturization and large capacity can be greatly advanced. It was

[0004]

As these miniaturized and large-capacity monolithic ceramic capacitors have been miniaturized, it has become difficult to display the lot symbol on the exterior parts. Further, in the case of the chip type, it has been difficult to display the lot in the past.

However, the lot symbol is important and necessary for investigating the cause of product defects and estimating the failure rate in the market.

An object of the present invention is to provide a monolithic ceramic capacitor capable of specifying a manufacturing time or a manufacturing lot at the time of malfunction investigation and failure analysis even in a miniaturized monolithic ceramic capacitor.

[0007]

A multilayer ceramic capacitor according to the present invention has a structure in which ceramic dielectrics and internal electrodes are alternately laminated, and each internal electrode is electrically connected to two external electrodes facing each other. In a monolithic ceramic capacitor whose basic structure is connection,
It is characterized in that at least one layer or a plurality of specific internal electrodes are exposed on the side surface of the sintered body near the external electrode extraction portion.

Further, the laminated ceramic capacitor of the present invention is characterized in that the internal electrode exposed on the side surface of the sintered body in the vicinity of the external electrode extraction portion is formed according to a specific law and corresponds to a manufacturing lot.

[0009]

The present invention will be described below with reference to the drawings. FIG. 1 is a front view, a plan sectional view and a front view of a finished product according to an embodiment of the present invention, and FIG. 2 is an internal electrode on a green sheet during a manufacturing process of a monolithic ceramic capacitor according to an embodiment of the present invention. It is an enlarged plan view of the process of printing a paste.

Green sheets on which internal electrodes are not printed. After stacking a plurality of green sheets shown in FIG. 2 (d), the green sheets shown in FIGS. 2 (b) and 2 (c) are alternately stacked. The green sheet of a) is used instead of the green sheet of FIG. 2C, a predetermined number of the green sheets of FIG. 2B are alternately stacked, and several green sheets of FIG. Get

After that, by a known method, A-A ₁ , B-
Cutting and firing are performed at points such as -B ₁ to obtain a front view of FIG. 1A and a cross-sectional view in the plane direction of FIG. 1B. Further, the external electrodes are baked to obtain the front view of FIG.

In the figure, 3 is a ceramic dielectric, 4 is an internal electrode, and 5 is an external electrode. Reference numeral 41 is an internal electrode exposed on the side surface for the purpose of displaying a lot. When the exposed portion is covered with an external electrode, the dimension of this exposed portion is slightly shorter than the silver coating dimension of the external electrode, and is preferably about 0.1 to 0.4 mm.

As described above, in this embodiment, the internal electrode layers (green sheet shown in FIG.
By increasing the number of sheets (corresponding to (a)), it is possible to easily deal with the manufacturing months 1 to 12 months and 1 to 24 months.

FIG. 3 is a side view of a fired product according to another embodiment of the present invention. In this embodiment, the weight is placed on the number of sheets from the outermost layer when the lot is displayed. For example, the outermost layer (lot-reading layer), followed by 2 ⁰ , 2 ¹ , 2
² , 2, ³ , and so on, and the lot symbol is indicated by this sum.
From this relationship, the lot code in (a) is 2 ⁰ × 0 +2 ¹ × 1
It becomes +2 ² × 1 = 6 and can be read as 6.

Since many of the actual products have more than 40 layers of internal electrodes, even if the number obtained by subtracting 2 from half is used for lot display, 18 layers, 2 ¹⁸ = 262,14
It is possible from 4,2 ¹⁹ −1 = 524,287 and lot display of about 500,000 or more.

In the lot display, one of the internal electrodes may be made to function every other layer. Even in this case, lots of 500 or more can be displayed.

When a manufacturing lot is read from a finished product, the layer indicating the lot can be easily displayed by removing only the external electrodes on the side surface of the external electrode layer, so that it can be read.

As an example of the use of the internal electrodes for the purpose of displaying lots, two examples are used in which the internal electrode on one side is used and the position is weighted by the power of the number of external electrode connection portions on the side surface to the power of 2 to correspond to the lot. I showed you, but this 2
It is possible to give various rules such as that the internal electrodes at both ends may be similarly configured without being bound by one.

Further, in the above-mentioned embodiment, the internal electrode exposed on the side surface of the sintered body was covered with the external electrode, but it is not always necessary to cover it.

[0020]

As described above, according to the present invention, the lot display is built in, and the manufacturing time can be specified at the time of defect investigation and failure analysis, and its industrial value is great.

Moreover, the number of manufacturing lots that can be displayed in lots can easily be configured to be hundreds of thousands or more, and extremely detailed lot traceability can be obtained, which is excellent.
Practical value is high.

[Brief description of drawings]

FIG. 1 is a front view after firing, a plane sectional view after firing and a front view of a finished product according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a step of printing an internal electrode paste on a green sheet during a manufacturing process of a chip type multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 3 is a front view of a chip type monolithic ceramic capacitor of another example of the present invention after sintering.

FIG. 4 is a sectional view of an example of a conventional chip type monolithic ceramic capacitor.

[Explanation of symbols]

 1 Green Sheet 2 Internal Electrode Paste 21 Internal Electrode Paste with Lot Display Function 3 Ceramic Dielectric 4 Internal Electrode 41 Internal Electrode for Lot Display 5 External Electrode

Claims (2)

[Claims] 1. The basic structure is that ceramic dielectrics and internal electrodes are alternately laminated, and each internal electrode is electrically connected to two external electrodes facing each other. A multilayer ceramic capacitor, characterized in that at least one layer or a plurality of specific internal electrodes are exposed on a side surface of a sintered body near an external electrode extraction part. 2. In the monolithic ceramic capacitor, an internal electrode exposed on a side surface of a sintered body in the vicinity of an external electrode extraction portion and covered with the external electrode is formed according to a specific rule, and is displayed on a manufacturing lot display. The monolithic ceramic capacitor according to claim 1, which is adapted to meet the requirements.