JPH0334204B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for adjusting the capacitance of a multilayer ceramic capacitor after it has been obtained. Note that "capacitance adjustment" as used in this invention is not limited to the concept of "capacitance trimming" in which minute capacitance adjustments are made to a completed multilayer ceramic capacitor, but also refers to changes in capacitance over a wider range. This also includes capacity adjustments.

2. Description of the Related Art Conventionally, one method for adjusting the capacitance of a completed multilayer ceramic capacitor is capacitance trimming using a sandblasting method. That is, this method reduces the effective overlapping area of the internal electrodes by sandblasting the outer surface of the multilayer ceramic capacitor, making holes that reach the internal electrodes inside, and scraping off part of the internal electrodes.
This method is partially used in the manufacture of multilayer ceramic capacitors that require small capacitance deviations.

Another method for adjusting the capacitance of a multilayer ceramic capacitor after completion is to provide a trimming electrode on the outer surface of the multilayer ceramic capacitor that faces the internal electrode, and then scrape it off using a sandblasting method to adjust the capacitance. There are ways to try to do this.

Problems to be Solved by the Invention The two typical conventional capacitance adjustment methods described above can be said to be suitable for capacitance adjustment in a minute range, but they are not suitable for adjusting capacitance values over a wide range. is not suitable. Also, when cutting internal electrodes or trimming electrodes, a relatively large mechanical shock is generated.
Part of multilayer ceramic capacitors. However, since the parts to which such mechanical impact is applied are parts directly involved in capacitance formation, such as internal electrodes and trimming electrodes, it may have an adverse effect on the characteristics of the multilayer ceramic capacitor itself.

Further, particularly in the former method described above, the holes left as a result of trimming are filled with a glass component or the like. Therefore, extra effort is required, and furthermore, even if the holes are filled, reliability problems will remain.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for adjusting the capacitance of a multilayer ceramic capacitor, which does not adversely affect the characteristics of the multilayer ceramic capacitor itself and allows the capacitance to be easily adjusted over a wider range. It is.

Means for Solving the Problems In the present invention, an extraction electrode that does not participate in capacitance formation and extends from a part of the internal electrode extending inside the laminate toward the surface of the laminate is electrically connected to an external electrode on the surface of the laminate. The external electrode is removed at the portion where it comes into contact with a specific one of the extraction electrodes, thereby cutting off the electrical connection between the external electrode and the specific internal electrode.

Effects In this invention, by partially removing the external electrodes, all the internal electrodes of a certain number can no longer contribute to capacitance formation. Therefore,
The range of capacity adjustment has become wider, and in extreme terms, from 0 to
Capacity adjustment is possible within a range of 100%. Also,
In this invention, since the connecting portion between the external electrode and the extraction electrode that is removed to perform such capacitance adjustment is not originally a place that is involved in capacitance formation, such removal allows the multilayer ceramic capacitor to be Its properties are not adversely affected. In addition, since no holes are drilled in the laminated body of the multilayer ceramic capacitor, there is no need for a subsequent process of filling the holes, making it possible to efficiently adjust the capacity and also prevent a decrease in reliability due to the presence of holes. .

Embodiment FIGS. 1 to 5 are diagrams for explaining an embodiment of the present invention.

First, in manufacturing the multilayer ceramic capacitor 1 as shown in FIG.
When the ceramic dielectric layers 2 and 3 shown in the figures are alternately laminated and then fired together, a laminate 4 as shown in FIG. 3 is obtained. Laminated body 4
The state of the internal electrodes formed inside has the following characteristics.

An internal electrode 5 is formed on one main surface of the ceramic dielectric layer 2 shown in FIG.
is formed. The lead electrode 6 extends to the edge of the ceramic dielectric layer 2. On the other hand, an internal electrode 7 is formed on one main surface of the ceramic dielectric layer 3 shown in FIG. 2, and an extraction electrode 8 is formed extending upward from the right end of the upper side of the internal electrode 7 in the figure. . This extraction electrode 8 also extends to the edge of the ceramic dielectric layer 3. When these ceramic dielectric layers 2 and 3 are stacked alternately, the dimension W of the laminate 4 matches the widthwise dimension W of the ceramic dielectric layers 2 and 3, as shown in FIG. , and the dimension T of the laminate 4 is the dimension W
Each ceramic dielectric layer 2,
A stacking number of 3 is selected.

In FIG. 3, therefore, the internal electrodes 5, 7 extending within the stack 4 are oriented vertically.
One of the extraction electrodes 6 is exposed and lined up at a position biased to the left side of the bottom surface of the laminate 4 in FIG. 3. On the other hand, the extraction electrodes 8 are exposed and lined up at a position closer to the right side of the upper surface of the laminate 4.

As shown in FIG. 4, external electrodes 9 and 10 are formed on the laminate 4 of FIG. 3. As shown in FIG. External electrode 9
is formed so as to cover the surface of the laminate in the portion where the extraction electrode 6 is exposed. The external electrode 10 is
It is formed so as to cover the surface of the laminate 4 in the portion where the extraction electrode 8 is exposed.

In this embodiment, the external electrodes 9 and 10 are both formed so as to cover the opposing end surfaces of the laminate 1 and a portion of the surface adjacent thereto, and the extraction electrodes 6,
It is formed so as to cover at least the exposed portion of 8. However, the edges 9 of the external electrodes 9, 10
As is clear from the fact that a and 10a extend parallel and obliquely to each other, the external electrodes 9 and 10 are
In the portions not in contact with the extraction electrodes 6 and 8, they are formed only in narrower areas. That is,
In terms of what appears in FIG. 4, the portion 9b of the external electrode 9 is narrower than the portion 10b of the external electrode 10. This is to facilitate the determination of the portion of the external electrode to be partially removed (for the external electrode 10, the portion 10b), which will be described later. Further, for example, the external electrode 10 formed to cover the extraction electrode 8 must be formed with a relatively large area in the portion 10b. Therefore, the distance from the portion 9b of the other external electrode 9 tends to become shorter. If this distance is short, there is a risk of a short circuit when such a multilayer ceramic capacitor 1 is mounted, so it is preferable to make this distance as long as possible. As a means for this, it is effective to narrow the width of the portion 9b of the external electrode 9. Note that the back side of the multilayer ceramic capacitor 1 shown in FIG. 4 has a similar structure.

As shown in FIG. 4, the multilayer ceramic capacitor 1 includes conductive paths 12,
13 using solder (not shown) or the like. This multilayer ceramic capacitor 1 can be easily adjusted in capacity even in the mounted state shown in FIG.

Referring to FIG. 5, there is shown a state in which multilayer ceramic capacitor 1 is undergoing or has undergone capacitance adjustment. Focusing on the portion 10b of the external electrode 10, a partially removed portion is shown there. By this,
Of the extraction electrodes 8, certain extraction electrodes, that is, extraction electrodes 8a and 8b, are directly exposed on the surface of the laminate 4, and these extraction electrodes 8a and 8b are electrically disconnected from the external electrode 10. There is. Therefore, the multilayer ceramic capacitor 1 in this state
has a total capacitance reduced by the capacitance contributed by the internal electrodes 7 connected to the extraction electrodes 8a and 8b. A well-known sandblasting method or laser trimming method can be used to remove a specific portion of the external electrode 10.

In addition, when the capacitance is adjusted after mounting the multilayer ceramic capacitor 1, the downward facing surface of the multilayer ceramic capacitor 1 shown in FIG. 4 may be turned up when mounting the multilayer ceramic capacitor 1. Even if you do that, this time,
The surface of the extraction electrode 6 in contact with the external electrode 9 appears, and similar capacitance adjustment can be performed by partially removing the external electrode 9. Therefore, the multilayer ceramic capacitor 1 as shown in FIG. 4 can be mounted on either the front or the back, and therefore no mounting errors can occur.

As described above, since the capacitance can be adjusted in the mounted state, this laminated ceramic capacitor 1 is advantageous in that the user can easily adjust the capacitance.

6 to 8 show other examples of laminated ceramic capacitors to which the present invention is applied. In this example, ceramic dielectric layers 14 and 15 shown in FIGS. 6 and 7, respectively, are alternately laminated to constitute a multilayer ceramic capacitor 16 as shown in FIG. 8.

On one main surface of the ceramic dielectric layer 14 in FIG.
8 is formed. On one main surface of the ceramic dielectric layer 15 shown in FIG. 7, an internal electrode 19 and a lead electrode 20 extending rightward from the center of the right side of the internal electrode 19 are formed.

As shown in FIG. 8, when external electrodes 22 and 23 are formed at both ends of the laminate 21, the external electrode 22 is electrically connected to the extraction electrode 18, and the external electrode 23 is connected to the extraction electrode 18. It will be in a state where it is electrically connected to 20.

In FIG. 8, there is a part of the external electrode 23 that has been removed, so that the extraction electrode 20
A is exposed to the outside. Therefore, the capacitance contributed by the extraction electrode 20a is reduced.

Leading electrodes 6, 7 and 1 in the two types of multilayer ceramic capacitors 1 and 16 described above
8 and 19 are not involved in capacitance formation,
Internal electrodes 5, 7 and 1 from which the extraction electrode is drawn out
It extends with a width narrower than the length of sides 7 and 19.
Therefore, electrical connection with a specific internal electrode can be severed by removing only a small portion of the external electrode. However, the extraction electrode may extend with the same width as the length of the side of the internal electrode from which the extraction electrode is extracted.

The capacity adjustment method of the present invention is particularly suitable for discontinuous, ie, stepwise, capacity adjustment. Therefore, for example, in the case of a crystal oscillation type watch, it is advantageous to apply the present invention when adjustment is not possible within the variable range of the trimmer capacitor included therein. In addition, the capacitance adjustment method according to the present invention can be used to adjust the capacitance as so-called capacitance trimming, and also to change the capacitance of individual multilayer ceramic capacitors by changing the degree of removal of external electrodes from the same multilayer ceramic capacitor. Therefore, it is effective for obtaining a wide variety of multilayer ceramic capacitors.

In addition, by making the areas of the internal electrodes included in one multilayer ceramic capacitor different from each other and selecting the internal electrode whose electrical connection with the external electrode is about to be severed, the range of change due to capacitance adjustment can be arbitrarily changed. It is also possible.

[Brief explanation of drawings]

1 and 2 are plan views showing ceramic dielectric layers included in a first example of a multilayer ceramic capacitor to which the present invention is applied. FIG. 3 is a perspective view showing a laminate obtained by laminating the ceramic dielectric layers shown in FIGS. 1 and 2. FIG. FIG. 4 is a perspective view showing a multilayer ceramic capacitor obtained using the laminate shown in FIG.
The mounting state of the multilayer ceramic capacitor is also shown. FIG. 5 is a plan view showing the laminated ceramic capacitor of FIG. 4 in which capacitance adjustment is being performed or has been performed. 6th
7 and 7 are plan views showing ceramic dielectric layers included in a second example of a multilayer ceramic capacitor to which the present invention is applied. FIG. 8 is a perspective view of a multilayer ceramic capacitor obtained using the ceramic dielectric layers shown in FIGS. 6 and 7, and also shows a state in which capacitance has been adjusted. In the figure, 1 and 16 are multilayer ceramic capacitors, 2, 3, 14, and 15 are ceramic dielectric layers, 4 and 21 are laminates, 5, 7, 17, and 19 are internal electrodes, and 6, 8, 18, and 20 are Extraction electrode, 9,1
0, 22, and 23 are external electrodes, and 11 is a circuit board.

Claims (1)

[Scope of Claims] 1 A plurality of internal electrodes are stacked with ceramic dielectric layers in between to form a laminate, and an extraction electrode extending from each internal electrode and not involved in capacitance formation is drawn out to the surface of the laminate. , a method for adjusting the capacitance of a multilayer ceramic capacitor in which an external electrode is formed on the surface of a laminate at a portion where an extraction electrode is exposed, the external electrode being removed at a portion in contact with a specific one of the extraction electrodes. A method for adjusting the capacitance of a multilayer ceramic capacitor, in which the electrical connection between the external electrode and a specific internal electrode is cut off. 2. The method for adjusting the capacitance of a multilayer ceramic capacitor according to claim 1, wherein the extraction electrode extends with a width narrower than the length of the side of the internal electrode from which the extraction electrode is drawn. 3 Claim 1 or 2, which is carried out in a state in which a multilayer ceramic capacitor is mounted.
Method for adjusting the capacitance of multilayer ceramic capacitors described in Section 1. 4. In the mounted state of the multilayer ceramic capacitor, the internal electrodes extend in a direction perpendicular to the mounting surface, and the extraction electrodes are drawn out to a surface on the laminate parallel to the mounting surface. Method for adjusting the capacitance of multilayer ceramic capacitors described in Section 1.