JPH09246094A - Trimmable layered ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic capacitor that is excellent in shock resistance and weather resistance after trimming and that is easy for manufacturing. SOLUTION: A trimming electrode 4 for adjusting the capacitance of a ceramic element 1 is arranged at the position nearer to either of the front surface or the back surface of the ceramic element 1 and the distance from the surface of the ceramic element 1 near to which the trimming electrode 4 is arranged to the trimming electrode 4 (that is the thickness t of a protecting ceramic layer) is 3μm to 20μm. The trimming electrode 4 is made of the same material as the material that constitutes an internal electrode 3 and a protecting ceramic layer 2a is constituted with the same ceramic material as the ceramic material that constitutes the ceramic element 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic ceramic capacitor, and more particularly to a trimmable monolithic ceramic capacitor capable of adjusting the magnitude of electrostatic capacitance.

[0002]

2. Description of the Related Art A monolithic ceramic capacitor is characterized by being small in size and capable of obtaining a large electrostatic capacitance, and is widely used in various applications.

Among the monolithic ceramic capacitors, there is a trimmable monolithic ceramic capacitor constructed so that its electrostatic capacity can be adjusted. FIG. 3 shows an example thereof. In this trimmable monolithic ceramic capacitor, internal electrodes 23 are arranged in the ceramic element 21 via the ceramic layer 22, and the surface of the ceramic element 21 is irradiated with a laser beam. A trimming electrode 24 for adjusting the electrostatic capacitance to a desired value by trimming is provided.
It is formed by disposing external electrodes 25 that are electrically connected to the internal electrodes 23, the trimming electrodes 24, etc. on both ends of the ceramic element 21.

However, in the above-mentioned conventional trimmable laminated ceramic capacitor, since the trimming electrode 24 is formed on the surface of the ceramic element 21, various kinds of thermal shock, chemical shock, mechanical shock, etc. are generated in the trimming process. It will be impacted, and will be affected by the operating environment even after trimming.

Therefore, conventionally, a thermally, chemically and mechanically stable material is used as the material for the trimming electrode, or it is coated with glass or the like to protect the trimming electrode from the ambient atmosphere. The method is taken.

However, in the above method, it is necessary to use a special material for the trimming electrode, which causes an increase in raw material cost, or it is necessary to separately form the trimming electrode after forming the ceramic element. Therefore, there is a problem that the manufacturing process becomes complicated. Further, the above method has a problem that a step of coating glass or the like is required, which complicates the manufacturing process and causes an increase in cost.

The present invention solves the above problems, and an object of the present invention is to provide a trimmable monolithic ceramic capacitor which is excellent in impact resistance and weather resistance after trimming and is easy to manufacture.

[0008]

In order to achieve the above object, a trimmable monolithic ceramic capacitor according to the present invention is provided with an internal electrode for forming a capacitance and a capacitance adjusting capacitor provided in a ceramic element. And a trimming electrode, wherein the trimming electrode is provided at a position close to at least one of both front and back surfaces of the ceramic element, and the trimming electrode is provided near the trimming electrode. The feature is that the distance from the surface of the element to the trimming electrode (that is, the thickness of the protective ceramic layer) is set to 3 to 20 μm.

As described above, the trimming electrode is arranged at a position close to the surface of the ceramic element, and the distance from the surface of the ceramic element to the trimming electrode (that is, the thickness of the protective ceramic layer) is 3 to 20 μm. It is possible to prevent the trimming electrode from coming into direct contact with the surrounding atmosphere, improve weather resistance after trimming, and prevent the interface between the trimming electrode and the ceramic element from being adversely affected when plating the external electrode. Like Further, it becomes possible to reliably prevent the trimming electrode from being damaged by coming into contact with other parts or members, and it is possible to obtain a highly reliable and trimmable monolithic ceramic capacitor having excellent durability. . Further, the manufacturing process can be simplified by forming the protective ceramic layer on the trimming electrode at the same time when manufacturing the ceramic element. Further, since the thickness of the protective ceramic layer is adjusted within the range of 3 to 20 μm, the position of the trimming electrode can be surely recognized from the surface of the ceramic element, and the usual trimming work can be performed. .

In the trimmable monolithic ceramic capacitor of the present invention, the trimming electrode can be easily and surely trimmed from the protective ceramic layer by using the laser beam.

Further, in the trimmable monolithic ceramic capacitor of the present invention, the thickness of the protective ceramic layer is 3 to.
The thickness of the protective ceramic layer is preferably 20 μm, but when the thickness of the protective ceramic layer is less than 3 μm, the effect of improving the weather resistance and impact resistance of the trimming electrode becomes insufficient, and the protective ceramic layer has a poor effect. If the thickness exceeds 20 μm, excessive energy is required for trimming, which deteriorates the trimming electrode and the ceramic layer around it, and makes it difficult to recognize the position of the trimming electrode from the surface of the ceramic element. The reason is that trimming cannot be performed easily.

In the trimmable monolithic ceramic capacitor of the present invention, the trimming electrode is made of the same material as the material of the internal electrode, and the protective ceramic layer is made of a ceramic material of the ceramic element. It is characterized by being composed of the same material as.

The trimming electrode is made of the same material as that of the internal electrode, and the protective ceramic layer is made of the same material as the ceramic material of the ceramic element. In the same way as in the case of manufacturing, the electrodes are printed on the ceramic green sheets, the ceramic green sheets are laminated after the electrodes are printed, the pressure bonding, and the subsequent firing is performed, and then the internal electrodes, trimming electrodes, protective ceramic layers, etc. The trimable multilayer ceramic capacitor of the present invention can be efficiently manufactured, and the present invention can be more effectively realized.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be shown and features thereof will be described in more detail. FIG.
FIG. 3 is a cross-sectional view showing a configuration of a trimmable monolithic ceramic capacitor according to an embodiment of the present invention.

As shown in FIG. 1, this trimmable monolithic ceramic capacitor has an internal electrode 3 and a trimming electrode 4 arranged in a ceramic element 1 with a ceramic layer 2 interposed therebetween, and at both ends of the ceramic element 1. It is configured by disposing an external electrode 5 that is electrically connected to the internal electrode 3, the trimming electrode 4, and the like.

In this trimmable monolithic ceramic capacitor, the trimming electrode 4 is constructed so that the capacitance can be adjusted by trimming with a laser beam, and the other internal electrode 3
And the same material (for example, Pd).

Further, in this trimmable monolithic ceramic capacitor, the ceramic layer 2a provided on the trimming electrode 4 is a protective ceramic layer for protecting the trimming electrode 4, and the thickness of the protective ceramic layer 2a. (That is, the distance from the upper surface of the ceramic element 1 to the trimming electrode 4) t is adjusted to 3 to 20 μm. The protective ceramic layer 2a is made of the same ceramic material as the other ceramic layers 2 (for example, titanium oxide-based ceramic material).

Next, a method of manufacturing the trimable multilayer ceramic capacitor will be described. First, a ceramic green sheet on which a predetermined internal electrode pattern is printed by a method such as screen printing,
Similarly, a ceramic green sheet on which a predetermined trimming electrode pattern is printed by a method such as screen printing is laminated, if necessary, via a ceramic green sheet on which no electrode is printed, and the ceramic on which the trimming electrode pattern is printed. A ceramic green sheet to be a protective ceramic layer is laminated on the green sheet and pressure-bonded to form a laminated block. Next, the laminated block is cut into individual ceramic elements 1 having a structure as shown in FIG. 1, and the ceramic elements 1 are heat-treated under predetermined conditions to sinter the ceramic elements 1. Then, an electrode paste is applied to both ends of the ceramic element 1 and baked to form the external electrodes 5, so that a trimmable monolithic ceramic capacitor as shown in FIG. 1 is obtained.

In the trimmable monolithic ceramic capacitor thus obtained, the trimming electrode 4 is arranged in the ceramic element 1, and the thickness t of the protective ceramic layer 2a thereon is in the range of 3 to 20 μm. Therefore, the trimming electrode 4 is prevented from coming into direct contact with the ambient atmosphere to improve the weather resistance after trimming, and the trimming electrode 4 is adversely affected when the external electrode 5 is plated. It is possible to reliably prevent damage to other parts or members by contacting them, and it is possible to improve durability.

The thickness t of the protective ceramic layer 2a is 3
Since it is adjusted to the range of ˜20 μm, the position of the trimming electrode 4 can be surely recognized from the surface of the ceramic element 1, and the trimming work can be performed efficiently.

In the trimmable monolithic ceramic capacitor of the above embodiment, the trimming electrode 4 is made of the same material as the material of the internal electrode 2, and the protective ceramic layer 2a is made of the ceramic material of the ceramic element 1. Since the same material as the material is used, the trimming electrode 4 and the protective ceramic layer 2a can be easily formed without requiring a special process,
The trimable multilayer ceramic capacitor of the present invention can be efficiently manufactured.

In the above embodiment, the case where the external electrode is formed after sintering the ceramic element 1 has been described, but the ceramic material, the internal electrode and the external electrode forming the ceramic element 1 are It is possible to manufacture the trimable multilayer ceramic capacitor of the present invention more efficiently by heat-treating (simultaneous firing) the ceramic element and the external electrode at once by appropriately selecting the constituent materials.

In the above embodiments, the case where only the outermost inner electrode on the front side (upper side) is used as the trimming electrode has been described. However, the innermost outer electrode on the back side (lower side) is used as the trimming electrode. It is also possible to use the outermost internal electrodes on both the front and back sides as trimming electrodes.

The present invention is not limited to the above-mentioned embodiment, but various applications and modifications can be made regarding the arrangement of trimming electrodes and internal electrodes, the number of laminated layers, and the like. As shown in FIG. 2, the trimming electrodes and the internal electrodes can be arranged in such a manner that the capacitor elements are connected in series, and other arrangements are also possible. Note that FIG.
In FIG. 1, the same reference numerals as those in FIG. 1 indicate the same parts.

The present invention is not limited to the above embodiments in other respects, and various applications and modifications can be made within the scope of the invention.

[0026]

As described above, in the trimmable monolithic ceramic capacitor of the present invention, the trimming electrode is arranged at a position close to the surface of the ceramic element, and the distance from the surface of the ceramic element to the trimming electrode (that is, the protective ceramic). Since the layer thickness) is 3 to 20 μm, it is possible to prevent the trimming electrode from directly contacting the surrounding atmosphere to improve the weather resistance after trimming, and the trimming electrode has a bad influence when plating the external electrode. It becomes possible to prevent receiving. In addition, it is possible to reliably prevent the trimming electrode from coming into contact with other parts or members and being damaged, and it is possible to obtain a highly reliable and trimmable laminated ceramic capacitor having excellent durability. Further, the protective ceramic layer on the trimming electrode is formed at the same time when the ceramic element is manufactured, so that the manufacturing process can be simplified. Further, since the thickness of the protective ceramic layer is adjusted within the range of 3 to 20 μm, the position of the trimming electrode can be surely recognized from the surface of the ceramic element, and the trimming work can be performed efficiently.

When the trimming electrode is made of the same material as that of the internal electrode and the protective ceramic layer is made of the same material as that of the ceramic element, the usual laminated ceramics are used. Internal electrodes, trimming electrodes, and protective ceramic layers are subjected to the same steps as in the production of capacitors, such as printing of electrodes on ceramic green sheets, lamination of ceramic green sheets after electrode printing, pressure bonding, and subsequent firing. It becomes possible to efficiently manufacture the trimmable monolithic ceramic capacitor of the present invention including the above, and the present invention can be more effectively realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a trimmable monolithic ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a trimmable monolithic ceramic capacitor according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional trimmable monolithic ceramic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ceramic element 2 ceramic layer 2a protective ceramic layer 3 internal electrode 4 trimming electrode 5 external electrode t thickness of protective ceramic layer

Claims (2)

[Claims] 1. A trimmable monolithic ceramic capacitor comprising an internal electrode for forming a capacitance and a trimming electrode for adjusting the capacitance, which is disposed in the ceramic element, wherein both front and back surfaces of the ceramic element. The trimming electrode is provided at a position close to at least one of the above, and the distance (that is, the thickness of the protective ceramic layer) from the surface of the ceramic element where the trimming electrode is provided near the trimming electrode to the trimming electrode is 3 to 20 μm. Trimmable monolithic ceramic capacitor characterized in that 2. The trimming electrode is made of the same material as that of the internal electrode, and the protective ceramic layer is made of the same material as that of the ceramic element. The trimmable monolithic ceramic capacitor according to claim 1.