JP2001339105A - Laminated piezoelectric ceramics and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated piezoelectric ceramics by which chipping due to its collision with other objects can be prevented and deterioration of a packaging characteristic due to thinning of a corner for packaging is prevented, and to provide its manufacturing method. SOLUTION: The laminated piezoelectric ceramics is a laminate which is provided with a plurality of laminated piezoelectric ceramics layers 1 in an n-corner shape (where n represents an integer of 3 or more) and internal electrodes 2 which are formed between the plurality of piezoelectric ceramics layers 1. The ceramics is provided with external electrodes 3 which are formed respectively so as to be extended to the lamination direction of the laminated on opposite side facers in the lamination direction, in such a way that the internal electrodes 2 become counter electrode in every other layer. A chamfering operation is executed at least to a part of corner parts which are sandwiched between two or more side faces in the lamination direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer piezoelectric ceramic structure such as a multilayer piezoelectric sensor for generating a voltage by applying pressure, a multilayer piezoelectric actuator for generating a displacement or a force by applying a voltage, and the like. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as this kind of laminated ceramics, there are those shown in FIGS. 5 (a) and 5 (b). FIG.
FIGS. 1A and 1B are diagrams showing an example of a laminated piezoelectric ceramic according to a conventional technique, wherein FIG. 1A is a plan view and FIG. 1B is a side view.

In the laminated piezoelectric ceramics 50 shown in FIGS. 5A and 5B, the internal electrodes 2 of the laminated piezoelectric ceramics 50 are partially formed on the piezoelectric ceramic sheet 1 before sintering with respect to the sectional shape. The piezoelectric ceramic sheet 1 on which the internal electrodes 2 are formed and the piezoelectric ceramic sheet 1 on which the internal electrodes 2 are not formed are cut out according to the shape of the laminated body, and the piezoelectric ceramic sheet 1 on which the internal electrodes 2 are formed is formed.
, And 25 piezoelectric ceramic sheets 1 on which the internal electrodes 2 were not formed were laminated such that the internal electrodes 2 became counter electrodes one by one, and were integrated by pressing to form a laminate. Obtained. Thereafter, the laminated body was sintered at 1100 ° C., and the cross-sectional shape was 10 × 10 mm and the length in the laminating direction was 20 mm.
The outer electrode 2 is formed by performing the outer shape processing and the formation of the external electrodes 2.

As described above, in the prior art, when processing the outer shape of the laminated piezoelectric ceramics 50, only processing for forming the outer shape of the laminated piezoelectric ceramics (upper and lower surfaces in the stacking direction and other side surfaces) is performed. Corner 5 sandwiched between
The technique which does not perform the processing of No. 1 was used.

[0005]

In the prior art,
Since only the processing to the dimensions conforming to the external shape of the laminated piezoelectric ceramics was performed, the angle of the corner 51 sandwiched between two or more surfaces is, for example, 90 ° in the case of a rectangular parallelepiped, and a triangular prism. In the case of, the angle of the corner sandwiched between the sides is 6
The angle was 0 °, and the smaller the number of prisms, the sharper the angle. Due to the presence of such corners 51, the chips in the manufacturing process collide with other members in the manufacturing process or peripheral members or the like at the time of being incorporated into a product using the laminated piezoelectric ceramics 50, thereby causing chipping. There was a drawback that it caused.

FIG. 6 is a view showing a state in which the conventional laminated piezoelectric ceramic 50 shown in FIG.

As shown in the plan view of FIG. 6, when the exterior 57 is applied to the laminated piezoelectric ceramics 50, the thickness of the exterior 57 is reduced at the corners 51, and if the purpose is to provide moisture resistance,
There was a defect that the thin corner portion 51 of the exterior 57 was broken by humidity.

FIG. 7 is a view from the top in the laminating cross section when the laminated piezoelectric ceramic shown in FIG. 5 is inserted into a cylindrical case. As shown in FIG. 7, when the laminated piezoelectric ceramics 50 is housed in a cylindrical case 58 and used, for example, the laminated piezoelectric ceramics 50 having a square prism having a square cross section on the lamination surface is placed in the cylindrical case 58. When inserting, the cross-sectional dimension of the laminated piezoelectric ceramics 50 is determined from its diagonal dimension and the diameter of the inner diameter of the cylindrical case 58,
The maximum value of the property relating to the cross-sectional shape was also determined.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent chipping of a laminated piezoelectric ceramic due to collision with another object and to prevent deterioration of exterior characteristics due to thinning at a corner at the time of exterior. An object of the present invention is to provide a laminated piezoelectric ceramic which can be manufactured and a method for manufacturing the same.

Another technical problem of the present invention is that
When a laminated piezoelectric ceramic is used by inserting it into a cylindrical case or the like, it is possible to provide a laminated piezoelectric ceramic capable of improving characteristics with respect to a cross-sectional shape when the inner diameter of the cylindrical case is fixed, and a method for manufacturing the same. is there.

[0011]

According to the present invention, a plurality of stacked n-sided (where n is an integer of 3 or more) piezoelectric ceramic layers are formed between the piezoelectric ceramic layers. A laminated body including an internal electrode, and external electrodes formed in the laminating direction such that the internal electrode becomes a counter electrode every other layer on opposite side surfaces in the laminating direction of the laminated body. In the laminated piezoelectric ceramics having the above, at least one of the corners sandwiched between the two or more side surfaces in the laminating direction is chamfered to obtain a laminated piezoelectric ceramic.

According to the present invention, an internal electrode is formed on an n-sided (where n is an integer of 3 or more) piezoelectric ceramic sheet before sintering, and two or more ceramic sheets on which the internal electrode is formed are further provided. And one or more piezoelectric ceramic sheets on which no internal electrodes are formed are laminated, pressed to form a laminate, and sintered, and an external electrode is formed on the side surface of the laminate so that every other internal electrode becomes a counter electrode. In the method for producing a laminated piezoelectric ceramic for forming an electrode, a method for producing a laminated piezoelectric ceramic is obtained, in which at least one of the corners sandwiched between two or more side surfaces in the laminating direction is chamfered. .

That is, in the present invention, part or all of the corners sandwiched between two or more surfaces of the laminated piezoelectric ceramic 1 are chamfered (R chamfering 5 or C chamfering 6). Accordingly, the angle of the corner of the laminated piezoelectric ceramic 1 is made obtuse or curved so that chipping due to collision with another object is less likely to occur. Also, in the present invention, two or more obtuse angles are formed by chamfering (R chamfering 5 or c chamfering 6) the corners sandwiched between two or more surfaces of the laminated piezoelectric ceramic 1. By forming the corners in a curved shape or in a curved shape, it is possible to prevent the exterior 7 from being thinned by the corners. Further, in the present invention, even when inserting into the cylindrical case 8 or the like, the corner chamfer (R chamfering 5
The cross-sectional area of the laminated piezoelectric ceramics entering a cylindrical case or the like is enlarged by chamfering 6).

[0014]

According to the present invention, there is provided a laminated piezoelectric ceramics comprising:
By chamfering a part or all of the corners sandwiched by one or more surfaces (forming a curved surface 5 by chamfering R or a flat surface 6 by chamfering C), chipping due to collision with another object is prevented. The occurrence can be reduced. In addition, even when the exterior 7 is provided, the thickness of the exterior 7 can be made uniform, and the characteristics obtained by the exterior 7 can be stabilized. Further, also in the case of insertion into the cylindrical case 8 or the like, it is possible to improve the characteristics affected by the cross-sectional shape by expanding the cross-sectional area.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are views showing the outer shape of a laminated piezoelectric ceramic according to a first embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a side view.

In the laminated piezoelectric ceramic 10 shown in FIGS. 1A and 1B, the internal electrodes 2 of the laminated piezoelectric ceramic 1 are partially formed on the piezoelectric ceramic sheet 1 before sintering with respect to the sectional shape. The piezoelectric ceramic sheet 1 on which the internal electrodes 2 are formed and the piezoelectric ceramic sheet 1 on which the internal electrodes 2 are not formed are cut out in accordance with the shape of the laminated body so that 150 piezoelectric ceramic sheets 1 on which the internal electrodes 2 are formed are formed. 25 piezoelectric ceramic sheets 1 on which the internal electrodes 2 were not formed were placed above and below the internal electrodes 2.
Each layer was laminated so as to be a counter electrode, and integrated by pressure bonding to obtain a laminated body. Thereafter, the laminate is formed by sintering at 1100 ° C. and performing external processing and forming the external electrodes 3 so as to have a cross-sectional shape of 10 × 10 mm and a length of 20 mm in the laminating direction. The above is the same as that of the prior art shown in FIG.

However, the laminated piezoelectric ceramic shown in FIG. 1 is a conventional piezoelectric ceramic shown in FIG.
Is formed, and then each corner is subjected to an R-surface processing with a radius of 1.0 mm by polishing, so that the structure is different from that of the prior art shown in FIG. In the multilayer piezoelectric ceramic according to the first embodiment of the present invention shown in FIG. 1, the corners sandwiched between the upper and lower surfaces in the stacking direction and other surfaces are not processed.

FIGS. 2A and 2B are views showing the outer shape of a laminated piezoelectric ceramic according to a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a side view. .

In the laminated piezoelectric ceramics 20 shown in FIGS. 2A and 2B, the internal electrodes 2 of the laminated piezoelectric ceramics 1 are partially formed on the piezoelectric ceramic sheet 1 before sintering with respect to the sectional shape. The piezoelectric ceramic sheet 1 on which the internal electrodes 2 are formed and the piezoelectric ceramic sheet 1 on which the internal electrodes 2 are not formed are cut out in accordance with the shape of the laminated body so that 150 piezoelectric ceramic sheets 1 on which the internal electrodes 2 are formed are formed. 25 piezoelectric ceramic sheets 1 on which the internal electrodes 2 were not formed were placed above and below the internal electrodes 2.
Each layer was laminated so as to be a counter electrode, and integrated by pressure bonding to obtain a laminated body. Thereafter, the laminate is formed by sintering at 1100 ° C. and performing external processing and forming the external electrodes 3 so as to have a cross-sectional shape of 10 × 10 mm and a length of 20 mm in the laminating direction. The above is the same as the multilayer piezoelectric ceramics 10 according to the first embodiment of the present invention shown in FIG. 1 and the multilayer piezoelectric ceramic 50 according to the prior art shown in FIG.

However, the laminated piezoelectric ceramic shown in FIG. 2 is a conventional piezoelectric ceramic external electrode 3 shown in FIG.
After forming the surface, each corner is subjected to a C-plane processing of 1.0 mm by polishing to form a surface 6, and thus, the laminated piezoelectric ceramic 10 according to the first embodiment shown in FIG.
The structure is different from that of the conventional laminated piezoelectric ceramics 50.

The laminated piezoelectric ceramic 20 shown in FIG.
Does not process the corners sandwiched between the upper and lower surfaces in the laminating direction and the other surface in the same manner as shown in FIG.

The following Table 1 shows that the laminated piezoelectric ceramics 10, 20, and 50 shown in FIGS. 1, 2, and 5 were dropped from a position having a height of 30 cm, and were colliding with another laminated piezoelectric ceramic. It is the result of having investigated the quantity of.

[0023]

[Table 1]

From the results shown in Table 1, it has been confirmed that the occurrence of chipping can be prevented by chamfering the corners and forming the curved surface 5 or the flat surface 6.

FIG. 3 shows the laminated piezoelectric ceramic 1 of FIG.
FIG. 7 is a diagram showing a state observed from the upper surface in the laminating direction when silicone exterior 7 is applied to 0. For comparison, FIG.
As shown in FIG. 5, a laminated piezoelectric ceramic having an exterior obtained by applying a silicone exterior 57 to the conventional laminated piezoelectric ceramic of FIG. 5 was prepared.

Table 2 below shows that the laminated piezoelectric ceramics 11 and 52 with the exterior shown in FIG. 3 and FIG.
It is a result of comparing the time until failure with MTTF (mean failure time) by applying DC 150 V in an atmosphere of 0%.

[0027]

[Table 2]

From the results shown in FIGS. 3 and 6 and Table 2 above, by forming the curved surface 5 by chamfering the corner 51, it is possible to prevent the exterior 7 from becoming thinner at the corner 51. It has been confirmed that can prevent a decrease in reliability caused by the thinning of the exterior 7.

FIG. 4 is a view from the top in the laminating cross section when the laminated piezoelectric ceramics 10 according to the first embodiment of the present invention is inserted into the cylindrical case 8 having an inner diameter of 10 mm.

For comparison, as shown in FIG.
5 was prepared by inserting the laminated piezoelectric ceramics shown in FIG. 5 into a cylindrical case 8 having an inner diameter of 10 mm similar to that of FIG.

In manufacturing, FIGS. 4 and 7
The space between the laminated piezoelectric ceramics 10 and the cylindrical case 8 that enter the case was designed to be 0.1 mm.

The laminated piezoelectric ceramic with a case shown in FIG. 4 is chamfered so that each corner of the laminated piezoelectric ceramic having a laminated sectional shape of 8.1 × 8.1 (mm) has a radius of 2.0 mm. Thus, a curved surface 5 is formed. Further, the laminated piezoelectric ceramics 50 in FIG. 7 is a square having a laminated sectional shape of 6.9 × 6.9 (mm).

Table 3 below shows the cross-sectional area and DC of the laminated piezoelectric ceramics 10, 50 shown in FIGS.
It shows the force generated when 150 (V) is applied.

[0034]

[Table 3]

From Table 3 above, it is possible to enlarge the cross-sectional area of the laminated piezoelectric ceramics 10 inserted into the cylindrical case 8 by chamfering the corners and forming the curved surface 5, and is further determined by the cross-sectional area. It was confirmed that the characteristics could be improved. Further, in the embodiment of the present invention, although the processing of the corners sandwiched between the upper and lower surfaces in the stacking direction and the other surface is not performed, even when these corners are chamfered,
The same effects as described above can be obtained.

[0036]

As described above, according to the present invention,
By chamfering (R chamfering 5 or C chamfering 6) part or all of the corners sandwiched between two or more surfaces of the laminated piezoelectric ceramics, any structure and shape can be obtained. A laminated type that can reduce the occurrence of chipping due to collision with other objects, and can also make the thickness of the exterior uniform when performing exterior, and stabilize the characteristics obtained by the exterior. Piezoelectric ceramics is now available.

Further, according to the present invention, even when the piezoelectric ceramic is inserted into a cylindrical case or the like, the cross-sectional area of the laminated piezoelectric ceramic can be enlarged, and the characteristics affected by the cross-sectional shape can be improved. Was.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a laminated piezoelectric ceramic according to a first embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a side view.

FIGS. 2A and 2B are views showing a laminated piezoelectric ceramic according to a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a side view.

FIG. 3 is a view from the top in the laminating direction when the laminated piezoelectric ceramic of FIG. 1 is provided with an exterior.

FIG. 4 is a view from the top in the laminating direction when the laminated piezoelectric ceramic of FIG. 1 is inserted into a cylindrical case.

5A and 5B are views showing an example of a laminated piezoelectric ceramic according to the prior art, wherein FIG. 5A is a plan view and FIG. 5B is a side view.

FIG. 6 is a view from the top in the lamination direction when the laminated piezoelectric ceramic of FIG. 5 is provided with an exterior.

7 is a view from the top in the laminating direction when the laminated piezoelectric ceramic of FIG. 5 is inserted into a cylindrical case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramic layer (piezoelectric ceramic sheet) 2 Internal electrode 3 External electrode 5 Curved surface 6 Plane 7,57 Exterior 8,58 Cylindrical case 10,20,50 Laminated piezoelectric ceramics 11,52 Laminated piezoelectric ceramic with exterior 51 Corner

Claims (2)

[Claims] 1. A laminate comprising a plurality of stacked n-sided (where n is an integer of 3 or more) piezoelectric ceramic layers and internal electrodes formed between the plurality of piezoelectric ceramic layers. In a laminated piezoelectric ceramic comprising external electrodes extending in the laminating direction so that the internal electrodes become opposing electrodes every other layer on opposite side surfaces in the laminating direction of the laminated body, A laminated piezoelectric ceramic, wherein at least a corner of a corner sandwiched between two or more side surfaces in the laminating direction is chamfered. 2. An internal electrode is formed on an n-sided (where n is an integer of 3 or more) piezoelectric ceramic sheet before sintering, and two or more ceramic sheets on which the internal electrode is formed and an internal electrode are formed. One or more piezoelectric ceramic sheets that did not exist are laminated, pressure-bonded to form a laminate, and sintered, and external electrodes are formed on the side surfaces of the laminate so that every other internal electrode becomes a counter electrode. A method for manufacturing a piezoelectric ceramic, comprising: chamfering at least a corner of a corner sandwiched between two or more side surfaces in a stacking direction.