JP2003152236A - Ceramic diaphragm structure and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable thin-wall ceramic diaphragm structure in which recesses, cracks, etc., do not occur in a diaphragm portion and which has a high natural resonance frequency, is excellent in strength, and does not hinder sintering at the time of sintering various kinds of films formed on its surface, and to provide a method by which the structure can be manufactured profitably. SOLUTION: The ceramic diaphragm structure is an integrally fired product composed of a ceramic substrate having at least one window section and a thin ceramic diaphragm plate laminated upon the substrate so as to cover the window section. In addition, a thin-wall diaphragm section is integrally formed with ceramic substrate at the window section. The diaphragm section is formed so that the section may be protruded outward in the direction opposite to the window section. In addition, the diaphragm section is protruded outward in the direction opposite to the window section at firing time when the ceramic diaphragm structure is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic diaphragm structure and a method for manufacturing the same, and more particularly to a ceramic diaphragm structure having a characteristic shape of a thin ceramic diaphragm portion and a method for advantageously manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a structure having a base body having at least one window as a support and covering the window with a flexible thin film material to form a diaphragm is a constituent member of various sensors. Etc., and in recent years, as a constituent member of a piezoelectric / electrostrictive actuator,
Has received attention. For example, when it is used as a sensor component, the diaphragm displacement of such a diaphragm structure is configured to be detected by an appropriate detection means for the bending displacement received by the object to be measured, and the piezoelectric / piezoelectric When used as a constituent member of an electrostrictive actuator, the diaphragm portion of such a diaphragm structure is deformed by a piezoelectric / electrostrictive element to apply pressure to a pressurizing chamber formed inside the structure. It will be used as it is produced.

Thus, such a diaphragm structure is manufactured by integrally assembling a base body as a support member constituting the diaphragm structure and a membrane member for providing the diaphragm. From the viewpoints of structural reliability, heat resistance, corrosion resistance, and the like, it is considered that such a diaphragm structure is composed of an integrally fired body of ceramics. 12
9360 (Japanese Patent Laid-Open No. 63-292032) and Japanese Patent Application No. 3
A pressure detector and a piezoelectric / electrostrictive actuator using a diaphragm structure made of ceramics obtained by integral firing have been disclosed as Japanese Patent Publication No. 204845 (JP-A-5-49270).

By the way, the ceramic diaphragm structure obtained by such integral firing is generally
Although it is obtained by firing an integral laminate of a ceramic green substrate having a predetermined shape having a window portion and a thin ceramic green sheet that covers the window portion, in such an integral firing operation, The present inventors have found that there is an inherent problem that the diaphragm portion formed from the ceramic green sheet located in the window portion of the ceramic green substrate is deformed into a concave shape or cracks are generated in the diaphragm portion. It became clear by the examination of. The occurrence of such dents and cracks in the diaphragm portion hinders the function or operation of the diaphragm and reduces its reliability.

Further, in such a ceramic diaphragm structure, the diaphragm portion is usually flattened. However, in such a flat diaphragm portion, its natural resonance frequency should be increased. In addition, it is difficult to reduce the thickness because the strength is not sufficient, and further, the electrode film or the piezoelectric / electrostrictive film formed on the surface cannot be sufficiently sintered. Such problems were inherent.

[0006]

Here, the present invention has been made in view of such circumstances, and the problem to be solved is that there is no occurrence of dents or cracks in a diaphragm portion, and its natural resonance frequency is To provide a highly reliable thin ceramic diaphragm structure that can be increased in size, has excellent strength, and does not hinder the sintering of various films formed on the surface. And to provide a method for advantageously manufacturing such a diaphragm structure.

[0007]

In order to solve such a problem, the present invention is an integral firing method comprising a ceramic base having at least one window and a thin ceramic diaphragm plate laminated so as to cover the window. A structure in which a thin diaphragm portion is integrally formed in the window portion, and the diaphragm portion is formed in a shape protruding outward in a direction opposite to the window portion. The gist is a ceramic diaphragm structure characterized by the following.

According to such an advantageous aspect of the ceramic diaphragm structure according to the present invention, the ceramic diaphragm plate is made of a material whose main component is stabilized zirconia, partially stabilized zirconia, alumina or a mixture thereof. It is configured.

According to a preferred aspect of the present invention, the ceramic substrate and the ceramic diaphragm plate are each formed to have an average crystal grain size of 5 μm or less, and the diaphragm portion has a thickness of 30 μm or less. Formed at a relative density of 90.
% Or more of a dense body.

In the present invention, in order to manufacture such a ceramic diaphragm structure, (a) a step of preparing a ceramic green substrate having at least one window portion, and (b) a thin wall having a predetermined thickness. And (c) a step of laminating the thin ceramic green sheets on the ceramic green substrate so as to cover the window part thereof to form an integral laminated body, (D) The laminate is fired to form an integral sintered body to form a thin diaphragm portion at the window portion of the ceramic green substrate, and at the same time as the firing of the laminate, the diaphragm portion is formed. The gist of the method is a method of manufacturing a ceramic diaphragm structure including a step of projecting outward in a direction opposite to the window portion. .

And in such a manufacturing method,
Advantageously, the ceramic green substrate and the ceramic green sheet have the following formula: S (substrate) −S (sheet) ≧ −0.08 {T ₇₀ (substrate)
-T ₇₀ (sheet)}-10 ≤ T ₇₀ (base) -T ₇₀ (sheet) ≤ 300 S (base) -S (sheet) ≤ 20 [where S (base) and S (sheet) are respectively Represents the shrinkage ratio (%) of the length in the plane direction when the ceramic green substrate and the ceramic green sheet are independently fired at the same temperature as the firing temperature of the laminate, and also T ₇₀ (base) and T ₇₀ ( The sheet represents the temperature (° C.) when the shrinkage rate of the ceramic green substrate: S (substrate) and the shrinkage rate of the ceramic green sheet: S (sheet) reach 70%, respectively. ] It is prepared so as to have a sintering temperature and a shrinkage ratio satisfying the above condition, and the diaphragm portion is projected outward as the laminate is fired.

In the preferred embodiment of the manufacturing method according to the present invention, the ceramic green sheet has a partially stabilized zirconia material, a fully stabilized zirconia material, and an alumina material having an average particle diameter of 0.05 to 1.0 μm. Alternatively, it is formed using a material whose main component is a mixed material thereof, or a material which becomes the material after firing. It should be noted that there is no problem even if 30% or less of an auxiliary agent is added to the above material.

In order to advantageously obtain the above-mentioned ceramic diaphragm structure according to the present invention, the present invention provides (a)
Preparing a ceramic green substrate having at least one window, (b) preparing a thin ceramic green sheet having a predetermined thickness, and (c) covering the ceramic green substrate with its window. To do
A step of laminating the thin ceramic green sheets to form an integral laminated body; and (e) firing the laminated body to form an integral sintered body, which is thin in the window portion of the ceramic green substrate. The step of forming the diaphragm part of
(F) a step of applying pressure to the diaphragm portion while heating the thus obtained sintered body to form the diaphragm portion in an outwardly convex shape. A method of manufacturing a diaphragm structure is also the subject of the invention.

[0014]

As described above, according to the present invention, in a ceramic diaphragm structure in which a thin diaphragm part is integrally formed so as to cover the window part provided in the ceramic base, such a diaphragm part is provided. , Which is projected to have a convex shape outward,
An example of such a ceramic diaphragm structure to which the present invention is applied is shown in FIGS. 1 and 2. In addition,
In the illustrated specific example, there is one window.

That is, in these drawings, the diaphragm structure 2 has a ceramic base 4 of a predetermined thickness as a support having a rectangular window 6 of a predetermined size, and the window 6 is superposed on one surface thereof. Is integrally formed with a thin ceramic diaphragm plate 8 for covering the above, and the portion of the diaphragm plate 8 located in the window portion 6 of the ceramic base 4 is the diaphragm portion 10. Then, such a diaphragm structure 2 is, as shown in FIG. 3, a thin ceramic green sheet 1 that provides a ceramic diaphragm plate 8.
2 to the ceramic green substrate 14 which provides the ceramic substrate 4 so as to cover the window 16 thereof,
It is manufactured by stacking and thermocompressing to form an integral laminated body, and then integrally firing the laminated body. The ceramic green sheet 12 and the ceramic green substrate 14 can be formed by stacking a plurality of sheet components or substrate components, respectively. Further, here, the shape of the window portion 6 of the diaphragm structure 2, that is, the shape of the diaphragm portion 10 is a rectangle (quadrangle), but the shape is not limited to this, and the diaphragm structure 2 is not limited thereto. Depending on the application, an arbitrary shape such as a circular shape, a polygonal shape, an elliptical shape, or a combination thereof is appropriately selected.

According to the present invention, in the diaphragm structure 2, the diaphragm portion 10 has an outwardly convex shape, that is, the side opposite to the window portion 6, as shown in an enlarged view in FIG. It is configured so as to have a curved shape protruding to, thereby preventing the occurrence of dents and cracks, as well as advantages not obtained in the flat diaphragm portion 10, such as an increase in natural resonance frequency, Improvement of strength against external force, avoidance of inhibition of sintering of the film formed on the outer surface of the diaphragm portion 10, etc. are advantageously achieved, and the application of the diaphragm structure 2 can be significantly expanded. Of. By the way, the natural resonance frequency f of the diaphragm 8 which is the diaphragm is (H
/ A ² ) √ (E / ρ) [However, 2A: diaphragm plate 8
Outer diameter, H: convex height, E: Young's modulus of material, ρ: density of material], the natural resonance frequency f can be arbitrarily changed by adjusting the convex height. is there. Specifically, if the convex height is increased, the rigidity can be increased even if the thin diaphragm plate 8 is used.
The natural resonance frequency f can be increased.

In this diaphragm structure 2, the amount of protrusion of the diaphragm portion 10 that is convex outward is appropriately determined according to the application of the diaphragm structure 2. Generally, in order to sufficiently exert the above-mentioned effects, the protrusion amount (h) near the central portion of the diaphragm portion 10 with respect to the shortest dimension (m) passing through the center of the window portion 6 in the ceramic base body 4,
In other words, the protrusion rate [y = (h / m) × 100], which represents the maximum protrusion amount (h) as a percentage, is 1% or more. Further, even if it is at the upper limit of the protrusion rate (y), it will be appropriately determined, but in general, it is 50%.
It is a degree.

Further, in the diaphragm structure 2 according to the present invention as described above, the ceramic substrate 4 forming the same is used.
And as a material for providing the ceramic diaphragm plate 8,
Although various known ceramic materials can be appropriately selected and used, among them, the ceramic diaphragm plate 8 is generally mullite, beryllia, spinel, titania, aluminum nitride, silicon nitride, stabilized zirconia, partially stabilized zirconia, It is formed of a material containing alumina or a mixed material thereof as a main component, and it is particularly preferable that the material is formed of a material containing stabilized zirconia or partially stabilized zirconia, alumina or a mixed material thereof as a main component. In particular, the present inventor et al.
As disclosed in Japanese Unexamined Patent Publication No. 12 etc., by adding a compound such as yttrium oxide, the crystal phase is mainly tetragonal, or mainly cubic, tetragonal and monoclinic,
By using a mixed crystal composed of at least two kinds of crystal phases, a material having zirconia partially stabilized as a main component is preferably used. The diaphragm plate 8 formed of such a material exhibits high strength, heat resistance and corrosion resistance, as well as excellent characteristics of being thin and flexible, and provides an effective diaphragm structure. In order to realize the integral structure of the diaphragm structure 2, it is desirable that the ceramic base body 4 is also made of the above-mentioned material similar to the ceramic diaphragm plate 8.
In addition, it is possible to use a ceramic material such as glass ceramics or cordierite.

Further, in such a diaphragm structure 2, the ceramic base 4 and the ceramic diaphragm plate 8 are provided.
From the viewpoint of mechanical strength, it is preferable that the ceramic constituting each (diaphragm portion 10) generally has a crystal grain size of 5 μm or less, preferably 3 μm or less, more preferably 1 μm or less. Further, in the window portion 6 of the ceramic substrate 4, the thin diaphragm portion 10
The thickness of the ceramic diaphragm plate 8 that gives
In terms of vibration characteristics, it is desirable that the thickness is 30 μm or less, and particularly 3 to 20 μm is more preferable. Further, as the density of such diaphragm plate 8, relative density (bulk density / theoretical density) is 90% or more From the viewpoint of material properties such as strength and Young's modulus, it is preferable that the content be 95% or more, and particularly preferably 98% or more.

The thickness and the degree of sintering of the ceramic substrate 4 constituting the diaphragm structure 2 are not particularly limited, and are appropriately determined depending on the purpose of use of the diaphragm structure 2. Also, such a ceramic substrate 4
As described above, not only is it composed of a single layer, but it does not matter if it has a multilayer structure. However, if it is composed of a ceramic material similar to that of the diaphragm plate 8, Is advantageous in terms of reliability of the laminated interface of

By the way, the ceramic diaphragm structure 2 having such a structure can be manufactured by various methods based on the knowledge of those skilled in the art. Particularly, in the present invention, the advantageous manufacturing method is used. As one of the above, a method having the following steps (a) to (d) is adopted.

That is, first, in the step (a),
As shown in FIG. 3, while a ceramic green substrate 14 having at least one window 16 is prepared,
In the step (b), a thin ceramic green sheet 12 having a predetermined thickness is prepared. When the ceramic green sheet 12 and the ceramic green substrate 14 are manufactured, the above-mentioned ceramic materials are appropriately used. Among them, the ceramic green sheet 12 has an average particle diameter of 0.05 to 1.0 μm. Will be formed using a partially stabilized zirconia material, a fully stabilized zirconia material, a material containing an alumina material or a mixed material thereof as a main component, or a material that becomes these materials after firing. . Further, with respect to the ceramic material, a slurry, a paste or the like is prepared by mixing an appropriate binder, a plasticizer, a dispersant, a sintering aid, an organic solvent and the like, as in the conventional case, and The paste is used to form a ceramic green sheet 12 or a ceramic green substrate 14 having a predetermined thickness according to a conventionally known method such as a doctor blade method, a calendar method, a printing method, a reverse roll coater method, and the like, and then, if necessary, By performing processing such as cutting, cutting and punching, or laminating a plurality of sheets, a molded product having a predetermined shape and thickness (ceramic green sheet 1
2 and a ceramic green substrate 14).

Further, when laminating, it is also advantageous to provide an adhesion auxiliary layer at the laminating interface.
Then, as the adhesion auxiliary layer, the binder, the plasticizer, the solvent or a mixture thereof, the slurry or the paste mainly containing the ceramic powder, and the like are used. In addition, it is also possible to perform this lamination simultaneously in the step (c).

Then, the ceramic green sheet 12 and the ceramic green substrate 14 thus prepared are laminated and laminated in the next step (c). That is, a thin ceramic green sheet 12 is laminated on the ceramic green substrate 14 so as to cover the window portion 16 thereof, and an integrated laminate is formed by thermocompression bonding or the like. Further, it is possible to provide an adhesion auxiliary layer also when performing this lamination.

Thereafter, in the step (d), a firing operation is performed on the laminated body, whereby the laminated body is made into an integral sintered body, and the window portion 16 portion of the ceramic green substrate 14 is formed. In, while forming a thin diaphragm portion (10), at the same time as firing the laminate, the diaphragm portion (10) is curved so as to be convex outward in a direction opposite to the window portion 16 (6). Then, the ceramic diaphragm structure 2 as shown in FIGS. 1 and 4 is made to project. The firing temperature at this time is generally about 1200 to 1700 ° C., preferably 1
A temperature of about 300 to 1600 ° C. will be adopted.

Thus, the ceramic green sheet 1
In order to make the diaphragm portion project outward in a curved shape at the same time as the firing of the laminated integrated body composed of 2 and the ceramic green substrate 14, the selection of the material of the ceramic material, the selection of the particle diameter of the material powder, Binder, dispersant,
The sintering speed and the firing shrinkage rate of the ceramic green sheet 12 and the ceramic green substrate 14 are controlled by selecting the additive such as the sintering aid and the degree of the addition amount thereof.
A method such that the diaphragm portion (10) formed of the ceramic green sheet 12 is curved outward with firing is adopted. Particularly, in the present invention, Ceramic green sheet 12
And the ceramic green substrate 14 have the following formula (a): S (substrate) -S (sheet) ≥ -0.08 {T ₇₀ (substrate)
-T ₇₀ (sheet)}-10 ≤ T ₇₀ (base) -T ₇₀ (sheet) ≤ 300 S (base) -S (sheet) ≤ 20 [where S (base) and S (sheet) are respectively Represents the shrinkage ratio (%) of the length in the plane direction when the ceramic green substrate and the ceramic green sheet are independently fired at the same temperature as the firing temperature of the laminate, and also T ₇₀ (base) and T ₇₀ ( The sheet represents the temperature (° C.) when the shrinkage rate of the ceramic green substrate: S (substrate) and the shrinkage rate of the ceramic green sheet: S (sheet) reach 70%, respectively. ] It is prepared so as to have a sintering temperature and a shrinkage ratio satisfying
As the laminate of the ceramic green sheet 12 and the ceramic green substrate 14 is fired, the diaphragm portion is advantageously projected outward.

In the above formula (a), the shrinkage ratio of the length in the plane direction is represented by [(length before firing-length after firing) / length before firing] × 100 (%). The surface direction at that time is not the thickness direction but a predetermined direction on the surface (main surface) on which the sheet or the base is molded.
Further, the temperature at which the shrinkage ratio reaches 70% is such that the shrinkage ratio calculated by the above formula is the total shrinkage ratio S% [S [S] [S] at the baking temperature for obtaining the diaphragm structure during the baking process.
(Substrate)% or S (sheet)%] is the shrinkage rate (0.7S%) multiplied by 0.7. Further, T is a scale for observing the sinterability, and the thinner ceramic green sheet 12 has a smaller ceramic green substrate 1.
From 4 above, the condition is that the sintering rate is equal or faster, but even if this condition is satisfied, a convex shape is obtained due to the shrinkage rate (S) at the firing temperature for obtaining the diaphragm structure. In order to obtain a flat shape or a flat shape, it is necessary to satisfy the relational expression between S and T in the above equation (a).

If there is too much difference in sinterability between the ceramic green sheet 12 and the ceramic green base 14, in other words, the value of T ₇₀ (base) -T ₇₀ (sheet) is 3.
When it is larger than 00, the convex shape becomes unstable,
It may cause cracks. Further, S is the firing temperature that is actually adopted when integrally firing the diaphragm structure,
It indicates the shrinkage rate when each sheet is fired alone, but if there is too much difference in this shrinkage rate, that is, S
When the value of (base) -S (sheet) is larger than 20, there is a problem that the warp of the diaphragm structure after firing becomes large or cracks are generated in the diaphragm plate 8.

In the above-mentioned manufacturing method of the ceramic diaphragm structure according to the present invention, from the viewpoints of stability of the convex shape of the diaphragm portion, amount of warp of the structure, stress remaining in the diaphragm plate after firing, etc., the following formula is preferable. (B): S (base) -S (sheet) ≥ -0.08 {T ₇₀ (base)
−T ₇₀ (sheet)} + 0.8 10 ≦ T ₇₀ (base) −T ₇₀ (sheet) ≦ 200 S (base) −S (sheet) ≦ 10 so that the ceramic green sheet 12 and the ceramic green base are satisfied. 14 is prepared, more preferably the following formula (C): S (base) -S (sheet) ≥ -0.08 {T ₇₀ (base)
−T ₇₀ (sheet)} + 0.8 10 ≦ T ₇₀ (base) −T ₇₀ (sheet) ≦ 100 S (base) −S (sheet) ≦ 5, so that the ceramic green sheet 12 and the ceramic green base are satisfied. 14 will be prepared.
The range defined by the above equations (a), (b) and (c) is illustrated in FIG.

Further, according to the present invention, as a second method capable of advantageously producing the ceramic diaphragm structure according to the present invention, an integral laminate obtained by the steps (a) to (c) above. First, in step (e), the laminate is fired to form an integral sintered body, and at the window portion 16 portion of the ceramic green substrate 14,
After forming the thin diaphragm portion (10), (f)
In the step, while heating the thus obtained sintered body, pressure is applied to the diaphragm portion (10) to form the diaphragm portion (10) in a convex shape outward. The manufacturing method consisting of will also be advantageously employed.

In the step (f) in the second manufacturing method, in order to make the diaphragm portion (10) of the sintered body, which has already been sintered, have an outwardly convex shape, it is first set at a sintering temperature. It is heated to an appropriate temperature which is the same as or lower than that to make it deformable, and a mechanical pressing force by an appropriate jig or the like is applied to the diaphragm portion (10), or a fluid is applied. By applying pressure or the like, it is possible to make the diaphragm portion (10) project outward. Then, the diaphragm portion (10) thus projected is then cooled to become the diaphragm structure 2 which projects outward at the desired projection amount (h). From the viewpoint of productivity, the first manufacturing method is more preferable.

The thin-walled ceramic diaphragm structure 2 according to the present invention thus obtained has no defects such as dents and cracks in its diaphragm portion 10.
In addition to providing good quality and high reliability, the strength is excellent, the natural resonance frequency can be increased, and the film formed on the outer surface of the diaphragm portion 10 can be sintered. It has no adverse effect and can be advantageously used for various applications such as sensors and actuators. Due to its material properties, this ceramic diaphragm structure can be used in combination with various sensing means such as strain gauges if it is applied to a part of equipment, piping, etc. under severe corrosion conditions. Although it can be used as a pressure sensor, and when used in combination with air pressure or a drive source such as a push rod, the frequency is low,
It can also be used as an actuator having a large displacement amount.

However, the thin ceramic diaphragm structure according to the present invention has a piezoelectric / electrostrictive operating portion provided on the surface on one side of the diaphragm portion and can be advantageously used as a piezoelectric / electrostrictive film type element. Yes, among others, bending displacement and force such as actuators, filters, displays, acceleration sensors and shock sensors, transformers, microphones, sounding bodies (speakers, etc.), unimorph type transducers and oscillators used for power and communication. It can be particularly advantageously used as a piezoelectric / electrostrictive film type element of a type that generates or detects bending displacement or force. Incidentally, FIG. 6 schematically shows an example of a piezoelectric / electrostrictive film type element using the thin ceramic diaphragm structure according to the present invention, and FIG. 7 is an exploded perspective view thereof. ing.
And, the piezoelectric / electrostrictive film type element 20 shown there is
The diaphragm structure 22 and the piezoelectric / electrostrictive actuating portion 24 arranged on the outer surface of the diaphragm portion are formed by being joined and integrated.
The electrostriction actuating portion 24 is configured to bend and deform the diaphragm portion of the diaphragm structure 22 according to the applied voltage.

More specifically, the diaphragm structure 22
Adopts the configuration according to the present invention, in which the closing plate (diaphragm portion) 26 and the connecting plate (base portion) 28 each having a thin flat plate shape made of a ceramic material such as zirconia are made of zirconia or the like. Spacer plate (base part) 30 made of a ceramic material
It is integrally formed with a structure in which they are overlapped with each other. The connection plate 28 is provided with a plurality of communication opening portions 32 (here, 3
Individual pieces) are formed and serve as a communication portion with the outside. Further, a plurality of square window portions 36 (here, three) are formed on the spacer plate 30, and are arranged at predetermined intervals in the longitudinal direction. And
The spacer plate 30 is superposed on the connection plate 28 so that each one of the communication openings 32 provided in the connection plate 28 is opened in each of the windows 36. Is there. It should be noted that the arrangement of the communication openings 32 is set in an appropriate number for each window 36 according to the application of the piezoelectric / electrostrictive film type element 20, and only one such as illustrated. Not only in the case of, but also in the number of two or more. Further, the shape, size, etc. of the communication opening can be appropriately selected according to the application. Further, a closing plate 26 is overlapped on the surface of the spacer plate 30 opposite to the side on which the connection plate 28 is overlapped.
The 6 openings are covered. As a result, a plurality of pressurizing chambers 38 are formed inside the diaphragm structure 22 so as to communicate with the outside through the communicating openings 32. Here, the three-layer structure of the closing plate (diaphragm part), the spacer plate (base part) and the connecting plate (base part) is taken as an example, but a four-layer or more multi-layer structure is also possible. .

Then, such a diaphragm structure 2
As described above, 2 is formed as an integrally fired product using a predetermined ceramic material such as zirconia, and its diaphragm portion (26) is convex outward in the direction opposite to the window portion 36. It is shaped. Specifically, first, a green sheet is prepared from a slurry or paste prepared from a predetermined ceramic material, a binder, a solvent and the like, using a general device such as a doctor blade device, a reverse roll coater device and a screen printing device. Molding, film formation, and then, if necessary, processing such as cutting, cutting, punching, etc., to form the window 36, the communication opening 32, etc., and the plates 26, 28,
After forming the 30 precursors, the precursors are laminated, thermocompression-bonded to form an integral laminate, and then, firing is performed to obtain an integral diaphragm structure 22, while The closing plate 26 that provides the diaphragm portion is formed in a shape that is convex outward by the means described above.

Further, in the diaphragm structure 22, the piezoelectric / piezoelectric material is provided at a portion corresponding to each pressurizing chamber 38 on an outer convex surface of the closing plate 26.
An electrostrictive operating unit 24 is provided. The piezoelectric / electrostrictive operating portion 24 is formed by sequentially forming the lower electrode 40, the piezoelectric / electrostrictive layer 42, and the upper electrode 44 on the outer surface of the closing plate 26, that is, the diaphragm portion by a film forming method. It is a thing. As the piezoelectric / electrostrictive actuating portion 24, the applicant of the present application has previously filed Japanese Patent Application No. 3-203.
The configuration of the piezoelectric / electrostrictive actuating portion 24 proposed in Japanese Patent Application No. 831 and Japanese Patent Application No. 3-204845 is advantageously adopted.

Then, such a piezoelectric / electrostrictive actuating portion 24
The electrode film (upper and lower electrodes 44, 40) and the piezoelectric / electrostrictive layer 42 for providing the film are formed by various known film forming methods, for example, thick film forming methods such as screen printing, spraying, dipping, coating, ion beam, and sputtering. It is formed on the outer surface of the closing plate 26 of the diaphragm structure 22 integrally formed by firing by a thin film forming method such as vacuum deposition, ion plating, CVD, and plating. In this case, as the forming material of the electrode films 40 and 44 and the forming material of the piezoelectric / electrostrictive layer 42, various known materials and materials disclosed in the above-cited applicant's patent application are appropriately used. Will be adopted by. In addition, the thickness of the piezoelectric / electrostrictive operating portion 24 composed of the electrode films 40 and 44 and the piezoelectric / electrostrictive layer 42 thus formed is generally 100 μm.
m or less, and the thickness of the electrode films 40 and 44 is
Generally, it is desirable that the thickness is 20 μm or less, preferably 5 μm or less. Further, the thickness of the piezoelectric / electrostrictive layer 42 is preferably 50 μm or less, more preferably 3 μm in order to obtain a large displacement at a low operating voltage. It is desirable that the thickness is 40 μm or less.

Therefore, such a diaphragm structure 2
Piezoelectric / electrostrictive actuating portion 2 on the diaphragm portion (26) of 2
In the piezoelectric / electrostrictive film type element 20 in which 4 is integrally provided, the displacement of the diaphragm portion (26) is effectively performed based on the operation of the piezoelectric / electrostrictive operating portion 24. As a result, the inside of the pressurizing chamber 38 is pressurized, and the fluid in the pressurizing chamber 38 can be effectively discharged.

In an advantageous application example of the diaphragm structure according to the present invention as described above, the diaphragm portion (26) of the diaphragm structure 22 has a shape protruding outward, so that the piezoelectric / electrostrictive structure is formed. The rigidity of the diaphragm part (26) provided with the operating part 24 can be effectively increased, and its mechanical strength and natural frequency can be effectively increased, and its response speed is advantageously increased. At the same time, it is possible to advantageously prevent the sintering of the piezoelectric / electrostrictive layer 42 and the like formed on the outer surface of the diaphragm portion (26) from being hindered, and to prevent the strain generated in the piezoelectric / electrostrictive operating portion 24 from occurring. In addition to exhibiting excellent characteristics such as being able to efficiently change stress into displacement, even when a plurality of piezoelectric / electrostrictive actuating portions 24 are driven simultaneously, the respective displacement amounts are the piezoelectric / electrostrictive operation. As compared with the case of a single drive parts 24,
A piezoelectric / electrostrictive film having a uniform quality and a uniform quality without a problem such as a change in the amount of displacement in the driving mode of the piezoelectric / electrostrictive actuating portion 24 without any significant decrease. It becomes the mold element 20. Further, the piezoelectric / electrostrictive film type element of this structure can also be used as a detector (sensor) for extracting bending displacement, force, etc. in the diaphragm portion as a voltage signal.

By the way, the above-mentioned thin ceramic diaphragm structure according to the present invention can be advantageously used as a constituent member of the piezoelectric / electrostrictive film type element as in the above example. As the structure of the film type element,
Needless to say, other than the above examples can be adopted.
In addition, speakers, sensors, oscillators, oscillators, filters,
In addition to displays, transformers, etc., unimorphs used in servo displacement elements, pulse drive motors, ultrasonic motors, etc. described in "Piezoelectric / electrostrictive actuators from basics to applications" by Kenji Uchino (Edited by Japan Industrial Center) (Morikita Publishing). Also, it can be advantageously used as a constituent member in various known uses such as a piezoelectric type or bimorph type piezoelectric / electrostrictive film type actuator.

[0041]

EXAMPLES Hereinafter, representative examples of the present invention will be shown to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. In addition to the following embodiments, the present invention further includes various changes and modifications based on the knowledge of those skilled in the art, in addition to the above specific description, without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

Example 1 First, the piezoelectric / electrostrictive film type device 20 shown in FIGS.
Various ceramic materials shown in Table 1 below were prepared in order to obtain the diaphragm structure 22 used in the above. Alumina, which is an additive, has the function of promoting the sintering of the ceramic material (zirconia) when it is added in a small amount, and has the effect of inhibiting the sintering when added in a large amount.

[0043]

[Table 1]

Next, using various ceramic materials, green sheets of various thicknesses are formed in accordance with a conventional method, and if necessary, further processed such as cutting, cutting and punching, and the like as shown in FIG. And various green bodies for the closing plate 26, the connecting plate 28, and the spacer plate 30, which are used for forming the diaphragm structure 22 for the piezoelectric / electrostrictive film type element 20 shown in FIG. It was made. It should be noted that the preparation of the green sheet forming slurry is carried out by using one of the predetermined ceramic material powders.
00 parts by volume, 60 parts by volume in total of polyvinyl butyral resin as a binder and dibutyl phthalate as a plasticizer, a sorbitan-based dispersant added as necessary, and toluene / isopropyl alcohol as a solvent. = 50/50 (volume ratio) with 500 parts by volume of the mixture in a ball mill for 5 to 200 hours, and the slurry thus obtained is degassed and closed. 2000 for 26
The target green sheet was formed by the doctor blade method after adjusting the viscosity so that it would be cps and 20000 cps for the connection plate 28 and the spacer plate 30. Further, the shrinkage ratio of the green sheet thus obtained is controlled by controlling the green density of the molded body by mixing time in a ball mill or addition of a sorbitan-based dispersant, or by controlling the maximum temperature reached during firing. By doing so. When the mixing time in the ball mill is long, the shrinkage rate becomes small, and the shrinkage rate also becomes small by the addition of the sorbitan-based dispersant, and the shrinkage rate becomes low by lowering the maximum temperature reached during firing. It gets smaller.

Various closing plates 26 thus obtained
Green body for connection plate 28 and green body for connection plate 28
Using the green body for the server plate 30, the following Table 2 and Table
Overlapping in 3 combinations, each 100 ℃ ×
1 minute, 200 kgf / cm²Laminated by thermocompression bonding under the conditions
An integrated product was produced. In addition, here, the connection plate 2
8 green body and spacer plate 30 green body
Are manufactured from the same green sheet.
The laminated integrated product thus obtained is shown in Table 4 below.
And firing at the firing temperature shown in Table 5 for 3 hours.
Then, various target diaphragm structures 22 were obtained. Na
The spacer plate in this diaphragm structure 22
The shape of the window portion 36 of the door 30, in other words, the diaphragm shape
As for the state, Is an odd number,
Circular, and in the case of an even number, 0.5 mm x 0.7
The rectangular shape of each of the windows is 0.
The width is 3 mm, and three window portions are formed. Note that the rectangle
The shape of the window is 0.5mm wide,
They are arranged at intervals of 0.3 mm. Also, Table 4
And Table 5 shows that the grease for the closure plate 26 to be combined is
Green body for connecting plate 28, spacer plate
Temperature difference during sintering with the green body for the sheet 30: ΔT ₇₀= T
₇₀(Substrate) -T₇₀(Sheet) and shrinkage difference: ΔS = S
The values of (base) -S (sheet) are also shown.

The shape of the diaphragm portion (26) of each of the 10 diaphragm structures obtained by firing in this manner was evaluated, including the presence or absence of cracks, and the shape was further projected outward. Then, the shape stability of the convex shape was evaluated from the variation of the convex amount. That is, each experiment No. Of diaphragm structure of
The individual pieces were evaluated in three grades from ◎ (excellent), ○ (good), and △ (acceptable), from those with little variation in convexity to those with many variations, and the results are also shown in Tables 4 and 5 below. It was

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

As is clear from the results of the production of the various diaphragm structures 22, for the closing plate 26 having the temperature difference during sintering: ΔT ₇₀ and the difference in shrinkage ratio: ΔS which satisfy the condition of the above-mentioned formula (a). Green body and connection plate 28
And the spacer plate 30 are used in combination with a green body to effectively prevent the occurrence of cracks and dents in the thin diaphragm portion (26) of the diaphragm structure 22 obtained, and The part can be advantageously formed in a shape that is convex outward.

Example 2 Experiment No. 1 in Example 1 A diaphragm structure 22 having a flat diaphragm portion (26) was obtained by using the same material and conditions as in Example 1 (however, in this case, the connecting plate 2).
8 are not overlaid). Next, in each of the windows 36 of the obtained diaphragm structure 22, an alumina ceramic pin having a convex shape is provided, and the ceramic pin is a diaphragm portion (26) of the diaphragm structure 22.
It was inserted so as to exert a pressing force on the inside from. Then, the diaphragm structure 22 is re-fired at a temperature of 1350 ° C. for 3 hours with the ceramic pin still inserted, and each diaphragm portion (26) has a shape protruding outward. I got body 22.
Then, the shape stability of the convex shape was evaluated by the same criteria as in Example 1, and was Δ (OK).

[0053]

As is apparent from the above description, in the ceramic diaphragm structure according to the present invention, the diaphragm portion has an outwardly convex shape, which allows the conventional flat structure. -Like diaphragm, which has not been obtained, for example, the natural resonance frequency can be advantageously increased, the strength against the force from the direction opposite to the window is improved, and the thickness of the outer surface of the diaphragm is increased. A thin ceramic diaphragm of high quality and high reliability, which has characteristics such as not interfering with the sintering of a film formed by a film method (for example, an electrode film or a piezoelectric / electrostrictive film). A structure can be provided.

Since the ceramic diaphragm structure according to the present invention is of the laminated type,
High integration is possible, and because it is an integrally fired product,
In addition to being highly reliable and easy to handle, the diaphragm shape can be freely designed, its convex height can be easily controlled, and productivity is very high. It has various advantages such as realization.

Further, according to the method of the present invention, the ceramic diaphragm structure having the above-mentioned excellent characteristics can be advantageously manufactured, and thus the industrial production of the ceramic diaphragm structure can be further improved. It's even easier.

The piezoelectric / electrostrictive film type element obtained by using such a ceramic diaphragm structure according to the present invention has a significantly improved operational reliability, whereby an actuator, a display and a filter are provided. , Microphones, sound generators (speakers, etc.), various sensors, various vibrators, oscillators, etc.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a basic structure of a thin zirconia diaphragm structure according to the present invention.

2 is a bottom view of the diaphragm structure shown in FIG. 1. FIG.

FIG. 3 is an explanatory diagram showing an example of a combination of a ceramic green sheet and a ceramic green substrate when manufacturing the diaphragm structure shown in FIG.

FIG. 4 is a partial explanatory view showing an enlarged cross section of a main part of the diaphragm structure shown in FIG.

FIG. 5 is a diagram showing a method for manufacturing a ceramic diaphragm structure according to the present invention, in which a difference in shrinkage ratio: ΔS and a temperature difference during sintering:
Is a graph showing the relationship between [Delta] T _70.

FIG. 6 is a cross-sectional view showing an example of a piezoelectric / electrostrictive film type element using a thin ceramic diaphragm structure according to the present invention.

FIG. 7 is an exploded perspective view of the piezoelectric / electrostrictive film type element shown in FIG.

[Explanation of symbols]

2,22 Diaphragm structure 4 Ceramic base 6,16,36 Window part 8 Diaphragm plate 10 Diaphragm part 12 Ceramic green sheet 14 Ceramic green base 20 Piezoelectric / electrostrictive film type element 24 Piezoelectric / electrostrictive operating part 26 Closing plate 28 Connection Plate 30 Spacer Plate 32 Opening Port for Communication 38 Pressurizing Chamber 40 Lower Electrode 42 Piezoelectric / Electrostrictive Layer 44 Upper Electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideo Masumori             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. (72) Inventor Katsuyuki Takeuchi             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. (72) Inventor Takahiro Maeda             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd.

Claims (9)

[Claims] 1. A monolithic fired product comprising a ceramic substrate having at least one window portion and a thin ceramic diaphragm plate laminated so as to cover the window portion, the diaphragm being thin in the window portion. A ceramic diaphragm structure characterized in that the diaphragm part is formed integrally with the diaphragm part, and the diaphragm part is convex outward in a direction opposite to the window part. 2. The ceramic diaphragm structure according to claim 1, wherein the ceramic diaphragm plate is made of a material whose main component is stabilized zirconia, partially stabilized zirconia, alumina or a mixed material thereof. 3. The ceramic diaphragm structure according to claim 1, wherein the ceramic substrate and the ceramic diaphragm plate each have an average crystal grain diameter of 5 μm or less. 4. The thickness of the diaphragm portion is 30 μm
The ceramic diaphragm structure according to any one of claims 1 to 3, which is as follows. 5. The relative density of the diaphragm portion is 90.
The ceramic diaphragm structure according to any one of claims 1 to 4, wherein the ceramic diaphragm structure is formed of a dense body of at least%. 6. A step of preparing a ceramic green substrate having at least one window portion, a step of preparing a thin ceramic green sheet having a predetermined thickness, and a step of covering the window portion with respect to the ceramic green substrate. As described above, a step of stacking the thin ceramic green sheets to form an integrated laminate, and firing the stack to form an integral sintered body, and forming a thin wall in the window portion of the ceramic green substrate. While forming the diaphragm portion, and simultaneously projecting the laminate, projecting the diaphragm portion in an outwardly convex shape in a direction opposite to the window portion, the ceramic diaphragm according to claim 1. Structure manufacturing method. 7. The ceramic green base and the ceramic green sheet have the following formula: S (base) -S (sheet) ≧ −0.08 {T ₇₀ (base).
-T ₇₀ (sheet)}-10 ≤ T ₇₀ (base) -T ₇₀ (sheet) ≤ 300 S (base) -S (sheet) ≤ 20 [where S (base) and S (sheet) are respectively Represents the shrinkage ratio (%) of the length in the plane direction when the ceramic green substrate and the ceramic green sheet are independently fired at the same temperature as the firing temperature of the laminate, and also T ₇₀ (base) and T ₇₀ ( The sheet represents the temperature (° C.) when the shrinkage rate of the ceramic green substrate: S (substrate) and the shrinkage rate of the ceramic green sheet: S (sheet) reach 70%, respectively. ] The manufacturing method according to claim 6, wherein the diaphragm portion is made to have a temperature in the middle of sintering and a shrinkage ratio satisfying the above condition, and the diaphragm portion is projected outward as the laminate is fired. 8. The ceramic green sheet has an average particle size of 0.05 to 1.0 μm, a partially stabilized zirconia material, a fully stabilized zirconia material, an alumina material or a mixed material thereof, or a material thereof after firing. 6. The method according to claim 6 or 7, wherein the material is formed of
The manufacturing method described in. 9. A step of preparing a ceramic green substrate having at least one window portion, a step of preparing a thin ceramic green sheet having a predetermined thickness, and a step of covering the window portion with respect to the ceramic green substrate. As described above, a step of laminating the thin ceramic green sheets to form an integrated laminate, and firing the laminate to form an integral sintered body, and forming a thin wall at the window portion of the ceramic green substrate. And a step of applying pressure to the diaphragm portion while heating the sintered body thus obtained to form the diaphragm portion in an outwardly convex shape. The method for manufacturing a ceramic diaphragm structure according to claim 1, wherein