JPH10106887A - Monolithic ceramic capacitor array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge the range of use or application, by causing the area of effective overlap portions of internal electrode patterns connected to one external electrode and corresponding internal electrode patterns connected to the other external electrode to differ from one another. SOLUTION: A dielectric material 6 made of BaTiO3 , or the like is molded on a dielectric ceramic sheet, and internal electrodes 2a, 2b are printed on the sheet by a screen printing method. In this case, using a screen mask in which the area of a printing pattern to be used is varied, one internal electrode pattern 2a and the other internal electrode pattern 2b are printed. Thus, after a predetermined numlrer of intenal electrodes are stacked, heated, pressurized, and then cut into a size for four elements by using a blade, the internal electrodes are fired at 1000 to 100 deg.C. Then, end portions of the internal electrodes are exposed, coated with an external electrode 4, and fired at 800 deg.C. Thus, by varying values A1 to A4 of the area of an effective overlap portion in individual patterns C1 to C4 , a capacitance of C1 ≠C2 ≠C3 ≠C4 may be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer ceramic capacitor. More specifically, the present invention relates to a multilayer ceramic capacitor array in which each element has a different capacitance.

[0002]

2. Description of the Related Art Multilayer ceramic capacitors are widely used in recent small electronic devices because of their high mounting efficiency.

FIG. 2 is a plan perspective view of a conventional multilayer ceramic capacitor array 10. FIG. FIG. 3 shows II- in FIG.
FIG. 2 is a sectional view taken along line II. 2 and 3, reference numerals 12a and 12b indicate internal electrodes connected to the external electrodes 14, and reference numeral 16 indicates a dielectric.

In general, a multilayer ceramic capacitor array is formed by printing internal electrodes 12a and 12b on a dielectric green sheet using a screen printing method, and stacking n pieces of these to form a green body. Internal electrodes 12a and 12
The area A of the overlapping portion of the b-pattern is an effective portion for obtaining a capacitance, and a desired capacitance is obtained by stacking n layers of internal electrodes. Each of the adjacent capacitor elements C _{1 to} C ₄ is insulated and isolated by the dielectric 16 and forms a capacitor array as a whole.

[0005] The capacitance is calculated as follows to obtain a desired capacitance. Cap = (ε · A · n) / t (where, ε is a dielectric constant, A is an effective area, and n
Is the number of effective parts, and t is the thickness of the dielectric.) However, in this case, in the capacitor array of FIG.
The ap (capacitance) is C ₁ ≒ C ₂ ≒ C ₃ ≒ C ₄ .

As described above, in the capacitor array as shown in FIG. 2, C ₁ ≒ C ₂ ≒ C ₃ ≒ C ₄ , and each element has the same capacitance. In such a capacitor array, the internal electrodes are provided on both upper and lower surfaces of the dielectric, so that as long as the same dielectric having the same thickness (t) and the same effective area (A) is used, there are various elements for each element. There is a problem that it is not possible to create a large capacitance. However, C ₁ ≠ C ₂ ≠ C ₃ ≠ C ₄ may be required depending on the circuit used.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to design the capacitance to various values even when the same dielectric material having the same size is used, for example, C ₁ ≠ C ₂ ≠ C ₃ ≠ to provide a multilayer ceramic capacitor array having a C _4.

[0008]

According to the present invention, a ceramic dielectric layer and a plurality of internal electrode layers arranged on the same plane of the ceramic dielectric layer are alternately laminated to form a substantially rectangular parallelepiped shape. In the multilayer ceramic capacitor having external electrodes connected to the internal electrode layers on two opposing side surfaces of the rectangular parallelepiped, each internal electrode pattern connected to one external electrode and the other external electrode are connected to the other external electrode. In addition, the present invention is solved by a multilayer ceramic capacitor array characterized in that the overlapping effective area with each corresponding internal electrode pattern is different from each other.

[0009]

FIG. 1 is a perspective plan view of an example of a multilayer ceramic capacitor array 1 according to the present invention. Ba
A dielectric material 6 made of TiO ₃ or the like is formed into a dielectric ceramic sheet by a known method.
a and 2b are printed by the screen printing method. On this occasion,
One internal electrode pattern 2a and the other internal electrode pattern 2b are printed using a screen mask in which the area of the print pattern used is changed. For example, one internal electrode pattern 2a is printed at the same length, and the other internal electrode pattern 2b is printed at a different length. In this way, a predetermined number of internal electrodes are laminated, heated and pressed,
After that, it is cut into a size of four elements using a razor. Thereafter, firing is performed at a temperature of about 1000 ° C. to 1300 ° C.
After firing, the end of the internal electrode was exposed by polishing or sandblasting, and the external electrode 4 was applied to the exposed surface of the internal electrode by dip printing, and fired at 800 ° C. to form the electrode. The external electrode is, for example, a thick film Ag paste or a thick film Ag.
/ Pd paste. Further, the outer surfaces of the external electrodes are plated with Ni and Sn / Pb by a conventional method.

As described above, one internal electrode pattern 2
a and the other internal electrode pattern 2b have different overlapping effective area for each pattern. That is, each pattern C
By changing the value A ₁ to A ₄ of the overlapping effective portion area in ₁ -C _4, In the same lamination number and the same dielectric thickness,
The capacitance of C ₁ 1C ₂ ≠ C ₃ ≠ C ₄ can be obtained.

Unlike the conventional capacitor array, in the capacitor of the present invention, the range of use or application can be expanded by changing the capacitance of each element of the array. For example, since the capacitance of each element is different, one element can exhibit the same function as four capacitors having the same capacitance. Therefore, the mounting speed is quadrupled because only one capacitor array of the present invention needs to be mounted while four capacitors having each capacitance are mounted.

Furthermore, when four conventional capacitors having respective capacitances are mounted, a space has to be provided between the capacitors. However, according to the capacitor array of the present invention, only one mounting is required. Therefore, the mounting space on the substrate can be greatly reduced.

The method of changing the overlapping effective area of one internal electrode pattern 2a and the other internal electrode pattern 2b is as follows.
(1) Using the pattern 2a and the pattern 2b having the same width,
The overlapping effective portion area is changed by changing the pattern 2a and the pattern 2b in the length direction (or the protruding direction), or (2) the pattern 2a and the pattern 2b having the same length but different widths are used. The pattern 2 in which the overlapping effective area is changed by using, that is, changing the width direction, or (3) the length and the width are appropriately changed
a and the pattern 2b to change the overlapping effective area. Either method can be used in the capacitor array of the present invention.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Dielectric constant ε = 10000, dielectric thickness t = 1
At 4 μm and the number of effective layers n = 18, the element C ₁ , in which the overlapping effective area A was changed by changing only the length direction,
C ₂ , C ₃ and C ₄ were prepared, and the capacitance of each element was measured. The results are summarized in Table 1 below.

[0015]

[Table 1]

[0016]

As described above, in the capacitor array of the present invention, the range of use or application can be expanded by changing the capacitance of each element. For example, since the capacitance of each of the four elements is different, one array can exhibit the same function as four capacitors having the same capacitance. Therefore, the mounting speed is quadrupled because only one capacitor array of the present invention needs to be mounted while four capacitors having each capacitance are mounted. Furthermore, when four conventional capacitors having respective capacitances are mounted, a space must be provided between the capacitors. However, according to the capacitor array of the present invention, only one mounting is required. The above mounting space can be greatly saved.

[Brief description of the drawings]

FIG. 1 is a plan perspective view of an example of a multilayer ceramic capacitor array of the present invention.

FIG. 2 is a plan perspective view of an example of a conventional multilayer ceramic capacitor array.

FIG. 3 is a sectional view taken along the line II-II in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2a, 2b Internal electrode 4 External electrode 6 Dielectric

Claims (2)

[Claims] 1. A ceramic dielectric layer and a plurality of internal electrode layers arranged on the same plane of the ceramic dielectric layer are alternately stacked, have a substantially rectangular parallelepiped shape, and are opposed to each other. In a multilayer ceramic capacitor having external electrodes connected to the internal electrode layers on two side surfaces, each internal electrode pattern connected to one external electrode and a corresponding internal electrode pattern connected to the other external electrode. And an overlapping effective part area different from each other. 2. The overlapping effective area is changed by changing the width and / or length of each internal electrode pattern connected to one external electrode and each corresponding internal electrode pattern connected to the other external electrode. 2. The multilayer ceramic capacitor array according to claim 1, wherein