JPH01158810A - Manufacture of electrostriction effect element - Google Patents

Abstract

PURPOSE:To improve the reliability by laminating a ceramic green sheet whose opening is formed in advance to the outside of an exciting electrode and compressing and sintering the laminated substance thereby eliminating the dispersion in the electrostriction characteristic. CONSTITUTION:Openings 22a, 24a are formed respectively to the ceramic green sheets 22, 24, and the openings 22a, 2a are formed to have a larger diameter than that of conductive pastes 26, 27 for the exciting electrode relatively, that is, to have a larger area relatively. The green sheets 21-25 are laminated and the laminated bodies are pressed in the broadwise direction and pressed and then sintered. Since cavities 32, 33 are formed based on the openings 22a, 24a formed accurately in advance, it is possible to form the cavities 32, 33 accurately with the designed size and shape, the electrostriction effect element 30 offering a stable electrostriction characteristic with excellent reliability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a method for manufacturing an electrostrictive element obtained by laminating and integrally firing a plurality of ceramic green sheets.

[Conventional technology]

FIG. 2 shows an example of a known electrostrictive element.

In order to obtain this electrostrictive effect element 1, first, a substrate 2 made of a piezoelectric material is prepared. Excitation electrodes 3 and 4 are formed on both sides of the substrate 2. Further, extraction electrodes 5 and 6 are formed so as to be connected to the excitation electrodes 3 and 4 and to extend to opposite edges of the substrate 2.

Next, the ceramic substrates 7 and 8 are brought close to each other from both sides of the substrate 2, and the substrates 2 are
Fixed against.

Here, as shown in the figure, each substrate 7.8 is placed in a state where the main surfaces of the substrates 7.8 are opposed to each other at a predetermined distance apart from the excitation electrodes 3 and 4 using adhesives 9 and 10 so as not to come into contact with the excitation electrodes 3 and 4. Retained. Therefore, when a voltage is applied from the extraction electrode 5.6, the excitation electrode 3.4 can vibrate the portion of the substrate 2 sandwiched between the excitation electrodes 3 and 4 without being hindered by the substrates 7 and 8.

On the other hand, as a method for manufacturing an electrostrictive effect element different from the above method, a method is known in which a plurality of ceramic green sheets are laminated, pressure-bonded, and then integrally fired.

In this method, a conductive paste for excitation electrodes is applied to both main surfaces of a ceramic electrostrictive material green sheet so that the front and back sides face each other, and at the same time, a conductive paste for extraction electrodes is applied, and then a conductive paste for an extraction electrode is applied on both main surfaces of the green sheet of a transferred electrostrictive material. After stacking flammable sheets that disappear at the temperature during firing or applying a flammable material paste on the excitation electrode, ceramic green sheets are further stacked and crimped on both sides of the electrostrictive material green sheet in the thickness direction, It is something that is fired.

Here, cavities are formed in the obtained sintered body by applying a flammable sheet or a flammable paste. Therefore, the structure is such that the portion of the electrostrictive material layer sandwiched between the excitation electrodes can freely vibrate during driving.

[Problem that the invention seeks to solve]

However, in the conventional manufacturing method for obtaining the structure shown in FIG. 2, it is difficult to prevent the adhesive 9, 10 from seeping out from the periphery to the center during bonding. the result,
The piezoelectric properties deteriorated, making it difficult to reliably obtain the designed properties. Therefore, strict control is required for the adhesives 9 and 10 and the bonding method, and the number of work steps increases.
There were difficulties in terms of mass production.

Not only that, but also because it uses adhesive 9.10,
There was also a natural limit to the operating temperature of the device.

On the other hand, by laminating multiple ceramic green sheets,
The method of integral firing after pressure bonding has a problem in that the above-mentioned cavity cannot be formed accurately. This problem will be explained with reference to FIG. FIG. 3 is a cross-sectional view of the obtained electrostrictive element. Here, an excitation electrode 12 is formed in a ceramic sintered body 11 exhibiting electrostriction, and an excitation electrode 13 is formed on the lower surface of the sintered body 12 so as to face the excitation electrode 12 in the thickness direction. has been done.

On the one side of the excitation electrode 12, a cavity 14 as shown in the figure is formed after firing by applying a combustible material that disappears at the firing temperature.

The cavity 14 is formed by, for example, applying a carbon paste containing carbon and an organic binder onto the conductive paste constituting the excitation electrode 12 prior to firing, laminating a ceramic green sheet on top of the conductive paste, pressing it, and then firing it. It is formed.

However, it is difficult to form the cavity 14 in the designed size and shape so as to surround the excitation electrode 12, and the cavity 14 may have an irregular shape as shown in the figure, or the upper ceramic portion may be shaped like the excitation electrode. There were times when I came into contact with parts of 12. That is, it is actually difficult to stably form the cavity 14 into a designed shape.

Therefore, it has been extremely difficult to realize stable electrostrictive characteristics.

Furthermore, with this method, it is difficult to form a large cavity, and therefore it is also difficult to obtain a large electrostrictive effect element.

There was also the problem that carbon reduced the electrostrictive ceramic material and deteriorated its characteristics.

Therefore, an object of the present invention is to provide a method that can reliably obtain an electrostrictive effect element that stably exhibits desired electrostrictive characteristics and has excellent reliability.

[Means for solving problems]

The method for manufacturing an electrostrictive element of the present invention is characterized by comprising the following steps.

That is, a pair of conductive pastes for excitation electrodes are arranged so as to be in contact with both principal surfaces of a ceramic electrostrictive material green sheet and a dielectric medium material green sheet, and to face each other in the thickness direction, and a conductive paste for each excitation electrode. A step of preparing a conductive paste for an extraction electrode arranged so as to reach the side edge of the electrostrictive material green sheet from the paste, and a conductive paste for an excitation electrode from at least one main surface side of the electrostrictive material green sheet. When a ceramic green sheet having an opening with a relatively larger area than the paste is viewed from the thickness direction, the conductive paste for the excitation electrode is located within the opening, either directly or with another ceramic green sheet. laminating a second ceramic green sheet on the outside of at least one of the ceramic green sheets in which the opening is formed, and closing the opening to obtain a laminate. , a step of applying pressure in the thickness direction of the laminate to bond the ceramic green sheets together and firing the same, and a step of applying an external electrode to the side surface from which the conductive paste for the lead-out electrode is drawn out. shall be.

Prior to lamination, there may be a step of filling the opening with a combustible material that disappears during firing, thereby making it possible to form the cavity or open recess more precisely.

[Effect]

In the present invention, a ceramic green sheet having the above-described openings is directly or indirectly laminated on the outside of the conductive paste for excitation electrodes, and an electrostrictive effect element is obtained by compressing and firing the laminated body. . Therefore, in the obtained electrostrictive effect element, a space or a cavity based on the above-mentioned opening is formed outside the excitation electrode, and this space or cavity is based on the opening previously formed in the green sheet state. It is reliably formed into the designed shape and size.

[Explanation of Examples]

FIG. 1 is an exploded perspective view for explaining a first embodiment of the present invention. First, five ceramic electrostrictive material green sheets 21 to 25 are prepared.

A conductive paste 26 for an excitation electrode is applied to one main surface of the central electrostrictive material green sheet 23 at the center. On the other main surface, a conductive paste 27 for excitation electrodes is applied so as to face the conductive paste 26 for excitation electrodes. Furthermore, conductive pastes 28 and 29 for extraction electrodes are applied from the conductive pastes 26 and 27 for each excitation electrode to the side edges of the ceramic green sheet 23.

The lead-out electrode conductive pastes 28 and 29 are drawn out to opposite edges as shown in the figure. This is because if the extraction electrodes formed after firing are opposed in the thickness direction, capacitance may occur between the extraction electrodes, which may change the characteristics.

In this example, the above ceramic green sheet 2
3. From both sides in the thickness direction, other ceramic green sea)
21, 22, 24, and 25 are stacked in the direction shown. By the way, openings 22a and 24a are formed in the ceramic green sheets 22 and 24 stacked on both sides of the ceramic green sheet 23, respectively. Opening 22a
, 24a are formed to have a relatively larger diameter, that is, a relatively larger area, than the excitation electrode conductive paste 26, 27.

Next, the ceramic green sheets 21 to 25 are stacked in the state shown in FIG. 1 to obtain a laminate.

In this case, the ceramic green sheets 22 to 24 are stacked so that the excitation electrode conductive pastes 26 and 27 are located within the openings 22a and 24a when viewed from the thickness direction.

Next, the laminate is pressed in the thickness direction to bond the ceramic green sheets together, and then fired. After firing, an external electrode is applied to the side surface of the sintered body, thereby obtaining an electrostrictive effect element 30 shown in FIG. 4.

As is clear from FIG. 4, excitation electrodes 26 and 27 (in this specification and the accompanying drawings, the conductive paste before firing and the conductive paste after firing The electrode portions formed by the paste will be described with the same reference numerals), and cavities 32 and 33 are formed on the outside thereof.

This cavity 32, 33 corresponds to the opening 22a in FIG.

24a. Therefore, the cavity 3 is formed based on the openings 22a and 24a that are accurately formed in advance.
2.33 is formed, so when mass-produced, the cavity 32.
33 can be formed accurately into the designed size and shape. Therefore, it is possible to obtain a highly reliable electrostrictive effect element 30 that exhibits stable electrostrictive characteristics.

In FIG. 4, reference numerals 34 and 35 indicate external electrodes, which are electrically connected to the extraction electrodes 28 and 29. The external electrodes 34 and 35 may be formed by baking silver paste onto the side surfaces of the sintered body 31 or by plating silver or copper, or by applying a conductive paste to the end surfaces of the laminate prior to sintering. However, during sintering, the excitation electrode 26.27
It may also be baked at the same time as the extraction electrodes 28 and 29.

In addition, in the embodiment shown in FIG. 1, the ceramic green sheet 2
All of Nos. 1 to 25 were made of materials containing electrostrictive materials, but
Only the central ceramic green sheet 23 may be formed of an electrostrictive material. This is because only the portion sandwiched between the excitation electrodes 26 and 27 is required to have electrostrictive characteristics. Although not particularly pointed out, this point also applies to the following examples.

FIGS. 5 to 8 each show an electrostrictive effect element obtained by a modification of the above-described embodiment.

In the electrostrictive effect element 37 shown in FIG.
A cavity 32 is formed only on the 6 side, and the other excitation electrode 27 side is exposed to the outside.

This is because the ceramic green sheets 24 and 25 are not used in the above embodiment.
It is obtained by laminating only 1 to 23 to obtain a laminate, followed by compression bonding and firing. Also in this case, the cavity 32 formed on one side of the excitation electrode 26 is accurately formed. Therefore, it can be seen that stable electrostrictive characteristics are exhibited as in the embodiment of FIG. 1.

In the electrostrictive element 39 shown in FIG.
An open recess 40 is formed on the outside of 7. This can be obtained by laminating the ceramic green sheets 21 to 24 shown in FIG. 1, compressing them in the thickness direction, and then firing them. That is, the open recess 40 is formed by the opening 24a of the ceramic green sheet 24.

As is clear from the electrostrictive effect elements 37 and 39 shown in FIGS. 5 and 6, in the present invention, ceramic green sheets having openings are laminated on either side of the excitation electrode conductive paste, It can be seen that it is only necessary to compress and sinter in the thickness direction, and the outer structure can be changed as appropriate.

FIG. 7 is a perspective view for explaining another embodiment of the present invention, and corresponds to FIG. 1. In this example,
Seven ceramic green sheets 51 to 57 are first prepared. Of these, the outermost ceramic green sheet 5
'l, 57 is the ceramic green sheet 21 of FIG.
25, and the ceramic green sheets 52 and 56 correspond to the ceramic green sheets 2 in FIG.
2°24, and each has an opening 52a.
, '56a are formed.

A conductive paste 58 for excitation electrodes is applied to one main surface of the ceramic green sheet 54 located at the center, and a conductive paste 59 for excitation electrodes is also applied to the ceramic green sheet 55 . The conductive bases 58 and 59 for excitation electrodes are formed so that when the ceramic green sheets 54 and 55 are laminated in the direction shown in the figure, the front and back sides face each other in the thickness direction with the electrostrictive material green sheets 54 interposed therebetween.

That is, the conductive paste for excitation electrodes in the present invention is
As in the embodiment shown in FIG. 1, two electrostrictive material green sheets may be formed so as to face each other on both principal surfaces, or as in this embodiment, green sheets laminated on both sides may be formed. It may be formed on the inner main surface. In short, it is only necessary that the pair of excitation electrode conductive pastes be arranged so as to be in contact with both main surfaces of the electrostrictive material green sheet and to face each other in the thickness direction.

Excitation electrode conductive pastes 60 and 61 are applied to each of the excitation electrode conductive pastes 58 and 59 so as to reach the side edges of the ceramic green sheets 54 and 55, respectively.

By the way, the ceramic green sheets 53.55 are relatively thinner than the ceramic green sheets 52, 54.56. Therefore, by stacking the ceramic green sheets 51 to 57 in the state shown in FIG. 7, compressing and firing the obtained laminate, an electrostrictive effect element 70 shown in FIG. 8 can be obtained. As is clear from FIG. 8, a cavity 64.65 is formed outside the excitation electrode 58.59 via a thin ceramic layer 62.63.

Therefore, since the excitation electrodes 58 and 59 are not exposed in the cavities 64 and 65, an electrostrictive element with excellent environmental resistance can be obtained.

In this embodiment as well, since the cavities 64 and 65 are formed by the openings 52a and 56a shown in FIG. 7, it goes without saying that when mass-produced, the cavities 64 and 65 can be reliably formed into a uniform shape. stomach.

9 and 10 are cross-sectional views showing an electrostrictive effect element obtained by a modification of the embodiment described with reference to FIG. 7. FIG. In FIG. 7, ceramic green sheet 5
1 to 55 are laminated, and then the resulting laminate is compressed and fired, an electrostrictive effect element 66 shown in FIG. 11 can be obtained. In addition, the ceramic green sheet 5 in Fig. 7
1 to 56 are laminated, and the resulting laminate is compressed and fired to obtain an electrostrictive effect element 67 shown in FIG. 10.

As is clear from FIGS. 9 and 10, in these electrostrictive elements 66 and 67, one of the excitation electrodes 58
A cavity 64 is formed on the side.

=15- In the example of FIG. 9, no cavity or opening is formed on the other excitation electrode 59 side. However, a ceramic layer 63 based on the ceramic green sheet 55 is formed, so that the excitation electrode 59 is not exposed to the outside.

In the example shown in FIG. 10, an open recess 68 is formed based on the opening 56a. It can be seen that in this example as well, since the ceramic layer 63 is formed, the other excitation electrode 59 is not exposed to the outside.

By the way, when obtaining an electrostrictive effect element using each of the above-described embodiments, it is necessary to stack a plurality of green sheets and then press them together. However, the opening 22a,
Since the ceramic green sheets 24a, 52a, and 56a are formed, cavities 12, 13 are formed in the laminate 71, as schematically shown in FIG. Therefore, when the molds 74, 75 are used to press the molds 74, 75 in the thickness direction, the cavities 72, 73 may collapse as shown in FIG. Therefore, preferably, as shown in FIG.
By using the molds 78, 79 having the above, the stacked body 71 can be crimped without crushing the cavities 72, 73 with pressure during crimping.

Further, without using the molds 78 and 79 as described above, the pressing force by the molds may be set to a level that does not crush the cavities 72 and 73.

However, in any case, the green sheet portion sandwiched between the excitation electrodes must be crimped in advance with normal crimping pressure.

Furthermore, after the ceramic green sheets shown in FIGS. 1 and 7 are laminated and pressure-bonded, a bonded molded body may be constructed using an adhesive, and the molded body may be fired. However, it is necessary to use an adhesive that does not adversely affect the ceramic during firing. Also,
In order to increase adhesive strength, it is preferable to incorporate a component of the ceramic green sheet into the adhesive to form a co-base.

FIGS. 14 to 18 are diagrams for explaining still another embodiment, in which the above-described opening is filled with a combustible material that disappears during firing, such as carbon paste.

That is, the ceramic green sheet 2 shown in FIG.
2 and the ceramic green sheet 23, a laminate 81 shown in FIGS. 14 and 15 can be obtained. In this embodiment, the 16th
A combustible material 82 is filled as shown in the figure and FIG. The combustible material 82 is selected from a material that disappears at the firing temperature when the laminate 81 is pressed and then fired.

Therefore, since the combustible material 82 is ultimately scattered, an open recess is formed on the outside of the excitation electrode 26 so as not to impede vibration, similar to the embodiment described above.

The combustible material 82 is filled in the opening 2 during crimping.
This is to prevent the shape of 2a from changing. Therefore, by filling with a suitable combustible material 82, an open recess can be formed more precisely on the outside of the excitation electrode.

Although carbon paste can be used as the combustible material 82, it is preferable to use ceramics or a material that does not affect the excitation electrode 26.

Furthermore, as shown in FIG. 18, when forming a thin ceramic layer 62 on the outside of the excitation electrode 26, that is, in a structure in which the ceramic green sheets 52 to 55 of FIG. In this way, an open recess can be accurately formed outside the excitation electrode 58.

Next, the characteristics of the electrostrictive element obtained in the embodiment shown in FIG. 1 will be explained with reference to FIG. 19. In FIG. 19, the solid line indicates the impedance-frequency characteristic of the element obtained in the example of FIG. 1, and the broken line indicates the impedance-frequency characteristic of the conventional example obtained by forming a cavity by printing carbon paste. show. As is clear from FIG. 19, in the conventional example, a response also appears in the frequency range based on the thickness of the entire element, and it can be seen that the response of the vibrating portion is also disturbed. On the other hand, it can be seen that in the electrostrictive element obtained in the example of FIG. 1, the response is limited to a frequency range corresponding to the thickness of the vibrating portion.

In addition, in the above-mentioned embodiment, a method for obtaining an electrostrictive effect element in which a pair of excitation electrodes were opposed to each other with an electrostrictive material layer interposed therebetween was explained. The present invention can be applied. For example, as shown in the cross-sectional view in FIG. 20, a pair of excitation electrodes 91.9
It is also possible to obtain an electrostrictive effect element 94 in which an electrode 92 is further disposed between the filter electrode 97 and the electrode 92 facing each other with an electrostrictive material layer in between. Filter electrodes 95,96 facing each other across the layers
The method of the present invention can be used to obtain a filter device 98 having: In these cases as well, the excitation electrode 9
1.92 and filter electrode 9', outside 96.97, cavities 101, 102. to3:
104 can be formed.

〔Effect of the invention〕

As described above, according to the present invention, ceramic green sheets with openings formed in advance are laminated directly or indirectly on the outside of the excitation electrode, and by compressing and firing the laminate, a cavity or an open space is formed on the outside of the excitation electrode. A recess is formed. Therefore, the electrostrictive material layer sandwiched between the excitation electrodes can be freely vibrated, and since cavities and open recesses are formed by the openings formed in the ceramic green sheet in advance, the shape and shape of the cavities and open recesses can be changed. The size can be accurately formed to the designed size. Therefore, when mass-produced, it is possible to obtain an electrostrictive effect element with no variation in electrostrictive properties and excellent reliability.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view for explaining the first embodiment of the present invention, FIG. 2 is a sectional view for explaining the conventional method, and FIG. 3 is a cross-sectional view for explaining another example of the conventional method. 4 is a sectional view of the electrostrictive effect element obtained through the steps of the embodiment shown in FIG. 1, and FIGS. 5 and 6 are for explaining modifications of the first embodiment of the present invention. FIG. 7 is an exploded perspective view for explaining the second embodiment of the present invention, and FIG. 8 is a cross-sectional view of the electrostrictive element obtained by each modification. FIGS. 9 and 10 are cross-sectional views showing electrostrictive elements obtained through the process, and FIGS. 11 to 13 are cross-sectional views for explaining a mold used for crimping, and FIGS. 14 to 17 are diagrams for explaining a third embodiment of the present invention. The figure is a perspective view of the laminate, No. 15.
The figure is a sectional view of the laminate, FIG. 16 is a perspective view showing a state filled with combustible material, FIG. 17 is a sectional view showing a state filled with combustible material, and FIG. 18 is a modification of the third embodiment. FIG. 19 is an impedance-frequency characteristic diagram showing characteristics of an embodiment of the present invention and a conventional example; FIGS. FIG. 7 is a cross-sectional view showing another example of an electrostrictive effect element to which the present invention is applied. In the figure, 21 to 25 are ceramic electrostrictive material green sheets, 22a and 24a are openings, 26°27 is a conductive paste for excitation electrodes, 28.29 is a conductive paste for extraction electrodes, 30 is an electrostrictive effect element, 32.33 is hollow, 34
．． 35 indicates an external electrode.

Claims (2)

[Claims] (1) A ceramic electrostrictive material green sheet, a pair of conductive pastes for excitation electrodes arranged so as to be in contact with both main surfaces of the ceramic electrostrictive material green sheet, and facing each other in the thickness direction, and each excitation electrode conductive paste. a step of preparing a conductive paste for an extraction electrode arranged so as to reach a side edge of the electrostrictive material green sheet from the conductive paste for the electrode; A ceramic green sheet having an opening having a relatively larger area than the conductive paste for excitation electrode is placed directly or by other means so that the conductive paste for excitation electrode is located within the opening when viewed from the thickness direction. laminating indirectly through ceramic green sheets; laminating a second ceramic green sheet on the outside of at least one of the ceramic green sheets in which the openings are formed; and closing the openings to form a laminate. a step of applying pressure in the thickness direction of the laminate to bond the ceramic green sheets together and firing the same, and a step of applying external electrodes to the side edges of the conductive paste for lead-out electrodes from which they are drawn out. A method for manufacturing an electrostrictive element, comprising: (2) The method for manufacturing an electrostrictive effect element according to claim 1, further comprising the step of filling the opening with a combustible material that disappears during firing, prior to the crimping.