JP3340043B2 - Piezoelectric actuator and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unimorph type or bimorph type actuator using a piezoelectric element, which generates a refractive displacement.

[0002]

2. Description of the Related Art Unimorph and bimorph actuators apply a voltage to a piezoelectric element bonded to a substrate to cause the piezoelectric element to bend and deform together with the substrate, thereby easily converting electrical energy to mechanical energy. It is a device that is running. This piezoelectric actuator is used particularly for a sounding body (such as a speaker), an ink jet printer head, and various vibrators. Further, this piezoelectric actuator is capable of expanding and outputting the displacement of the piezoelectric element, and has excellent positioning accuracy on the order of microns.

FIG. 4 shows an example of an ink jet printer head using the piezoelectric actuator 10 as an ink pump. The general structure of this head is as follows: a head substrate 20 having an ink chamber 21 and a nozzle 22 communicating therewith;
The piezoelectric actuator 10 is joined. The piezoelectric actuator 10 is provided with a piezoelectric element 2 having an upper electrode 4 via a bonding layer 5 on the surface of a thin substrate 1 serving as a vibration plate for applying pressure to each ink chamber 21. And
The piezoelectric element 2 and the substrate 1 are deformed by applying a voltage between the upper electrode 4 and the substrate 1 forming the lower electrode, and the ink chamber 21
By increasing the pressure in the ink (not shown)
Is ejected from the nozzle 22.

The substrate 1 and the head substrate 20 are formed of a metal material. Although only one ink chamber 21 is shown in the figure, a plurality of similar ones are arranged in a line to constitute an ink jet head. I have.

Further, Japanese Patent Application Laid-Open Nos.
As shown in JP-A-218929 and the like, it has been proposed to use ceramics as a material of the ink jet head.

For example, a head substrate 20 having the same structure as that shown in FIG. 4 and made of a ceramic mainly composed of any one of aluminum oxide, magnesium oxide and zirconium oxide is provided on a substrate made of a ceramic mainly composed of zirconium oxide. 1, a piezoelectric element 2 such as PZT is sandwiched between an upper electrode 4 and a bonding layer 5 that forms a lower electrode.

As a method of manufacturing these piezoelectric actuators 10, a piezoelectric element 2 previously processed into a predetermined shape is used.
A method in which the substrate 1 is fixed on the substrate 1 by a bonding layer 5 such as an adhesive or a low melting point glass, or as described in the above publications, the substrate 1 is made of ceramics having excellent heat resistance, and a piezoelectric material A method has been proposed in which a film having a predetermined shape is formed using a paste or slurry containing ceramic particles as a main component, and then bonded to a substrate by firing.

The piezoelectric actuator 10 is widely used as a sounding body and other various vibrators in addition to the ink jet head.

[0009]

By the way, in the ink jet printer head and the like mentioned in the above example,
From the viewpoint of improving printing quality and printing speed, the piezoelectric actuator 10 is required to operate at a lower voltage and have a higher response speed.
In order to realize such characteristics, the piezoelectric elements 2 on the substrate 1 serving as a vibration plate are arranged with high density and high accuracy, and each of the piezoelectric elements 2 arranged on the substrate 1 is accurately and without variation. It is necessary to reduce the size. Such miniaturization of the piezoelectric element 2 contributes to the refinement of the shape and operation of a general unimorph-type and bimorph-type piezoelectric actuator.

However, in the piezoelectric actuator 10 shown in FIG. 4, the unevenness of the joint between the substrate 1 and the piezoelectric element 2 causes variations in the drive characteristics of the actuator, or excessive stress on the joint layer during driving. There has been a problem that concentration occurs and the piezoelectric element 2 is damaged or peeled off.

Further, in the above-described method for manufacturing a piezoelectric actuator, it is difficult to form a small-sized piezoelectric element 2 with high precision, and as a result, there is a problem that reliability is reduced when the actuator is driven.

For example, in the case of a manufacturing method in which a piezoelectric element 2 formed in a predetermined shape is joined to a substrate 1, it is difficult to process the piezoelectric element 2 into a predetermined small shape. In particular, when the piezoelectric element 2 is made thinner, it is liable to be broken at the time of processing or bonding to the substrate 1, so that the yield of the piezoelectric actuator is reduced throughout the manufacturing process. Furthermore, when many piezoelectric elements 2 are arranged on the substrate 1, it has been difficult to accurately position these piezoelectric elements 2.

On the other hand, in the case of the manufacturing method in which the piezoelectric element 2 is formed by forming a film using a paste or slurry containing a piezoelectric ceramic as a main component, the shape of the piezoelectric element 2 before firing is unstable, and the piezoelectric element 2 is damaged. There was a problem that it was easy. Further, in the subsequent firing, it is difficult to control the shrinkage of the ceramic film forming the piezoelectric element 2, and there is a problem that the yield is deteriorated due to a dimensional defect of the piezoelectric element 2 obtained after firing.

Therefore, when a conventional piezoelectric actuator is used for an ink-jet head, the size of each piezoelectric element 2 formed on the substrate 1 varies, so that the ink ejection performance varies for each nozzle, and the driving performance of the head is reduced. Had the problem of affecting

The present invention has been made in view of such circumstances, and has as its object to provide a bimorph type, which is used for an ink jet printer head, a sounding body (such as a speaker), various vibrators, and the like. It is an object of the present invention to provide a unimorph type piezoelectric actuator which has a stable characteristic while enabling miniaturization and high precision, and a manufacturing method for realizing the stable production thereof.

[0016]

[MEANS FOR SOLVING THE PROBLEMS] The present invention provides a method for manufacturing a semiconductor device comprising:
In a piezoelectric actuator in which a piezoelectric element having electrodes is bonded via a bonding layer, a concave curved surface portion having a radius of curvature of 0.5 μm to 80 μm is formed on a side surface of the bonding layer.

Further, the present invention is characterized in that the piezoelectric element is set such that the side surface forms an angle of 0 ° to 45 ° with respect to the vertical direction.

According to the present invention, the side surface of the bonding layer interposed between the substrate and the piezoelectric element has a radius of curvature of 0.5 μm to 80 μm.
Because the concave curved surface portion of μm is formed, even when stress generated by deformation of the piezoelectric element is applied to the bonding layer when the piezoelectric actuator is driven, the stress is applied to the bonding layer by the concave curved surface portion provided on the side surface of the bonding layer. The piezoelectric element can be firmly bonded to the substrate by effectively preventing the bonding layer from peeling off. In addition, in this case, since the concave curved surface portion is formed on the bonding layer made of a relatively soft adhesive or various coupling agents, there is a problem that the bonding layer is chipped or cracked when the concave curved surface portion is formed. This is effectively prevented, and the productivity of the piezoelectric actuator is kept high.

Further, according to the present invention, by setting the side surface of the piezoelectric element at an angle of 0 ° to 45 ° with respect to the vertical direction, the piezoelectric element can be easily deformed while preventing damage to the ends. be able to.

Further, according to the present invention, the piezoelectric element may include lead zirconate titanate (PZT type), lead magnesium niobate (PMN type), lead nickel niobate (PNN type), lead manganese niobate, antimony stannate. lead, zinc lead niobate, a piezoelectric ceramic to Nakano one or mainly of two or more of lead titanate, its thickness is 1 [mu] m to 1
It is characterized in that it is 00 μm.

The above-mentioned piezoelectric ceramics have not only excellent piezoelectric properties but also good workability for blasting, compared with many of the following various substrate materials. Thus, when the piezoelectric element on the substrate is subjected to the blast processing, the piezoelectric element in the processing target portion can be satisfactorily removed.

Further, the present invention relates to a method for producing ZrO _{2 ,} Al ₂ O ₃ , Si ₃
A piezoelectric element having electrodes is provided on a substrate made of ceramic, glass, or a metal material of stainless steel, titanium, nickel, copper, or aluminum alloy containing N ₄ as a main component, or a resin material having high elasticity. In the piezoelectric actuator, a concave curved portion having a radius of curvature of 0.5 μm to 80 μm is formed at a boundary between the piezoelectric element and the substrate.

As the material of the substrate, it is preferable to use a material having higher durability against the blasting process than the piezoelectric element.

Further, according to the present invention, a plate-shaped or film-shaped piezoelectric element is bonded to a substrate, a mask is formed on the piezoelectric element, and the piezoelectric element in the non-mask portion is removed by high-precision fine blasting. And a method of manufacturing a piezoelectric actuator comprising a step of processing a side surface of a joint between a piezoelectric element and a thin substrate into a concave curved surface.

That is, according to the present invention, the boundary between the piezoelectric element and the substrate is recessed with a predetermined radius of curvature by adjusting the conditions of the blasting by performing the blasting after forming the mask. It is easy to make the shape of the curved surface or the side surface of the piezoelectric element a predetermined slope.

In addition, a piezoelectric element having an arbitrary shape according to the mask pattern can be formed on the substrate, and a large number of small piezoelectric elements can be easily arranged with high density and high precision on the substrate. In addition, if this manufacturing method is applied to a piezoelectric actuator used for an ink jet head, the dimensions and positioning of each piezoelectric element arranged on the substrate can be made extremely high precision, and the ink ejection performance of each nozzle can be made uniform. . Further, in the present invention, by processing after fixing the piezoelectric element on the substrate, the problem of positioning of the piezoelectric element on the substrate and breakage at the time of joining can be solved.

The above-mentioned JP-A-6-113396 or JP-A-7-115232 describes a manufacturing method using blasting, which is different from the present invention. That is, in the method disclosed in the above publication, blast processing is performed to adjust the surface roughness of the piezoelectric element itself or the surface roughness of the metal substrate, and the piezoelectric element is processed into a predetermined shape as in the present invention. Not for.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings by taking an ink jet head as an example.

The ink jet head shown in FIG. 1 has a structure in which a piezoelectric actuator 10 is joined to the upper surface of a head substrate 20 in which an ink chamber 21 and a nozzle 22 are formed.
In the piezoelectric actuator 10, a piezoelectric element 2 is bonded to a thin substrate 1 via a bonding layer 5, and an upper electrode 4 is provided on an upper surface of the piezoelectric element 2. Each piezoelectric element 2
Is provided at a position corresponding to the ink chamber 21,
It has a shape in which one end 2a is connected.

Here, when the substrate 1 is formed of a conductive material such as a metal, the substrate 1 itself can be used as a lower electrode. In other cases, the bonding layer 5 is formed of a conductive material and the lower electrode is formed. Can be achieved. When a voltage is applied between these electrodes, the piezoelectric element 2 and the substrate 1 are deformed and pressurize the ink chamber 21, so that ink (not shown) can be ejected from the nozzle 22.

As shown in the enlarged sectional view of FIG. 3, the radius of curvature R at the boundary between the substrate 1 and the piezoelectric element 2 is 0.5 to 0.5.
The concave curved surface portion 7 of 80 μm is formed, and the side surface 2b of the piezoelectric element 2 is a slope having an angle α with respect to the vertical direction of 45 ° or less. Therefore, even when stress is applied to the joint between the substrate 1 and the piezoelectric element 2 when the piezoelectric actuator 10 is driven, the stress concentration occurs because the concave curved surface portion 7 exists and the side surface 2a of the piezoelectric element 2 is inclined. And the breakage or peeling of the piezoelectric element 2 can be prevented. In addition, since the side surface 2a of the piezoelectric element 2 is inclined, the deformation of the piezoelectric element 2 can be facilitated.

The radius of curvature R of the concave curved surface portion 7 is set to 0.
The reason why the thickness is set to 5 to 80 μm is that if the radius of curvature R is less than 0.5 μm, the effect of relaxing the stress is poor, while if it exceeds 80 μm, the piezoelectric element 2 becomes difficult to sufficiently deform.

The curvature radius R of the concave curved surface portion 7 is measured based on a photograph obtained by enlarging a predetermined cross section to about 200 to 20000 times using a scanning electron microscope (SEM) or the like. Furthermore, the concave curved surface portion 7 is formed at the end of the bonding layer 5 and the piezoelectric element 2 on the substrate 1 side, and the substrate 1 and the piezoelectric element 2
Is preferably present over the entire range of the joint, but may be partially present.

As described in detail later, such a concave curved surface portion 7 can be easily formed to have a predetermined radius of curvature R by performing blasting.

Further, according to the present invention, as the material of the piezoelectric element 2, lead zirconate titanate (PZT type), lead magnesium niobate (PMN type), lead nickel niobate (P
NN), lead manganese niobate, lead antimony stannate,
Using piezoelectric ceramics containing one or more kinds of lead zinc niobate, lead titanate or the like as main components, the thickness is 1 to
It is preferably 100 μm.

The above-described piezoelectric ceramics have not only excellent piezoelectric properties but also good workability for blasting, compared with many of the various materials for the substrate 1 described below. Accordingly, when the piezoelectric element 2 on the substrate 1 is subjected to the blast processing, the piezoelectric element 2 in the processing target portion can be satisfactorily removed.

On the other hand, the material of the substrate 1 is ZrO.
₂ , ceramics, glass, or stainless steel, titanium, nickel, mainly containing Al ₂ O ₃ , Si ₃ N _4, etc.
A metal material such as copper or an aluminum alloy, a highly elastic resin material, or the like is used. In any case, it is preferable to use a material having higher durability to blast processing than the piezoelectric element 2 described above.

Platinum, silver, silver-palladium, or the like is used as the material of the bonding layer 5 when the upper electrode 4 and the lower electrode are also used, and the material of the bonding layer 5 when the lower electrode is not used is glass. , Adhesives, various coupling agents, and the like.

Next, a description will be given of a method of manufacturing the piezoelectric actuator 10 of the present invention when the substrate 1 forms a lower electrode.

First, as shown in FIG. 2A, a plate-shaped piezoelectric element 2 is bonded to the surface of a substrate 1 via a bonding layer 5, and then, as shown in FIG. Next, a mask 3 having a comb-like pattern is formed. SiC from above the mask 3
Alternatively, by performing blast processing for spraying fine particles 6 such as Al ₂ O _{3, the} partial piezoelectric element 2 without the mask 3 and the bonding layer 5 can be removed. After that, if the mask 3 is removed, as shown in FIG. 2C, the shape of the piezoelectric element 2 can be made to be the same comb shape as the mask 3, and the upper electrode 4 can be formed on the piezoelectric element 2. Thus, the piezoelectric actuator 10 shown in FIG. 1 can be obtained.

Hereinafter, each of the above steps will be described in detail. First, in the step shown in FIG. 2A, an adhesive forming the bonding layer 5, various coupling agents, and the like are coated with various known thick film forming methods such as screen printing, spraying, dipping, and the like.
After being formed on the surface of the substrate 1 by a thick film forming technique such as coating, the plate-like piezoelectric element 2 is bonded.

Next, in a step shown in FIG. 2B, a mask 3 made of a photosensitive resin, a metal plate or the like is formed on the piezoelectric element 2. When a photosensitive resin is used as the mask 3, the photosensitive resin is applied to the entire surface of the piezoelectric element 2 by the above-described thick film forming method, or a photosensitive resin sheet previously formed to a predetermined thickness is attached. Thereafter, a mask having a predetermined shape is formed by providing a shield having a predetermined shape on the photosensitive resin layer and exposing the mask. According to such a method, the mask 3 having an extremely fine shape can be formed with high accuracy,
As a result, the piezoelectric element 2 having a fine shape can be formed with high accuracy. When a metal is used for the mask 3, a predetermined pattern is formed in advance by punching or the like, and this is fixed on the piezoelectric element 2 with an adhesive or the like.

Thereafter, blasting is performed from above the mask 3 to process the piezoelectric element 2 into a predetermined shape.
The mask 3 is removed as shown in FIG. 3, but if necessary, the fine particles 6 used for processing are removed by air jetting or ultrasonic cleaning.
The fine powder of the processed piezoelectric element 2 is removed.

After that, the upper electrode 4 is formed on the surface of the piezoelectric element 2, and the upper electrode 4 can be formed by various known film forming methods. For example, it can be formed by a thick film forming technique such as screen printing, spraying, dipping, or coating, or a thin film forming technique such as ion beam, sputtering, vacuum deposition, ion plating, CVD, or plating. Which method is used is determined depending on the material of the substrate 1 or the material characteristics of the bonding layer 5, particularly, its heat-resistant temperature.

As another form of the manufacturing method, it is possible to form the upper electrode 4 in advance at the stage of FIG. 2A, form the mask 3 thereon, and then perform blast processing. In this case, as shown in FIG. 3, the piezoelectric actuator 10 can be obtained by removing the upper electrode 4, the piezoelectric element 2, and the bonding layer 5 in a portion without the mask 3 and removing the mask 3 after processing.

As another embodiment of the manufacturing method, the substrate 1
Is formed of an insulator, and the bonding layer 5 is also used as a lower electrode, in the following manner.

First, on a substrate 1 made of a heat-resistant insulating material,
An electrode paste forming the bonding layer 5 also serving as a lower electrode is applied by the above-described various film forming methods, and a piezoelectric ceramic paste or slurry forming the piezoelectric element 2 is formed thereon by the above various film forming methods. By simultaneously firing these, a structure in which the bonding layer 5 also serving as the lower electrode and the piezoelectric element 2 are laminated on the substrate 1 can be obtained as shown in FIG. After that, the same method as described above may be used.

In any of the above manufacturing methods, FIG.
When the blast processing is performed with the fine particles 6 as shown in FIG. 7, the boundary between the substrate 1 and the piezoelectric element 2 tends to have a concave curved surface, and the concave curved surface 7 can be easily formed. Similarly, the side surface 2b of the piezoelectric element 2 can be easily formed into a slope. At this time, if the particle size of the fine particles 6, the conditions of the blasting, and the like are changed, the concave curved surface portion 7 having the predetermined radius of curvature R and the side surface 2b having the predetermined angle α can be formed.

At this time, as shown in FIG. 3B, the bonding layer 5 may be partially connected without being completely divided.

When the head substrate 20 is bonded under the substrate 1 like the ink jet head shown in FIG. 1, the head substrate 20 in which the ink chambers 21 and the nozzles 22 are formed is bonded to the substrate 1 in advance. Thereafter, the piezoelectric element 2 can be formed on the substrate 1 by the above method.

In this case, there is a possibility that the substrate 1 may be damaged by the gas pressure of the blasting at the portion of the substrate 1 covering the ink chamber 21. In such a case, the gas pressure during blasting is supported by the liquid in the ink chamber 21 by filling the ink chamber 21 by injecting an incompressible liquid in advance and closing the ink flow path and the nozzle 22. Can be. After the blast processing, the ink flow path and the nozzle 22 may be opened, and the liquid in the ink chamber 21 may be heated at a low temperature or naturally evaporated.

The structure and shape of the piezoelectric actuator 10 of the present invention are not limited to the above.
In the above embodiment, an example in which the present invention is applied to an ink jet head has been described.
Can be used in various fields as a sounding body and other various vibrating bodies.

[0053]

EXAMPLE A piezoelectric actuator 10 of the present invention was manufactured by the manufacturing method shown in FIG.

A 30-μm-thick ceramic green sheet containing zirconate titanate (PZT) as a main component was punched out in a plate shape by a mold and fired to produce a plate-shaped piezoelectric element 2. At this time, in order to prevent warpage, a binder was removed and baked with a weight.

Next, as shown in FIG.
A melting point of 500 ° C.
A bonding layer 5 made of the following low-melting glass paste is formed by screen printing, and after drying, the plate-shaped piezoelectric element 2 is formed.
Were superimposed, a weight was placed thereon, and a heat treatment was performed at about 500 ° C. for about 5 minutes to join the two.

Next, a photosensitive resin sheet is stuck on the piezoelectric element plate 2 and the photosensitive resin is exposed so as to leave a predetermined mask pattern, as shown in FIG. A mask 3 was formed thereon. This mask 3
After removing the piezoelectric element 2 and the bonding layer 5 from the inner portion of the mask 3 by performing blasting from above, the remaining mask 3 is removed, and the piezoelectric element 2 having the shape shown in FIG. I got

Thereafter, an upper electrode 4 made of silver was deposited on the piezoelectric element 2, wiring was performed, and polarization of the piezoelectric element 2 was performed to obtain a piezoelectric actuator 10.

The piezoelectric actuator 10 manufactured as described above operates satisfactorily, and particularly the piezoelectric element 2 and the substrate 1
The peeling at the bonding surface of the substrate and the damage to the edge of the piezoelectric element 2 were reduced, and an actuator having excellent reliability was realized. In addition, even when a plurality of piezoelectric elements 2 are formed on one substrate 1, variations in the shape and driving characteristics of the piezoelectric elements 2 are reduced. Further, since the piezoelectric element 2 is processed integrally with the substrate 1, handling is facilitated, and the product yield is improved.

In particular, when the piezoelectric actuator 10 of the present invention is applied to an ink jet head, it is possible to accurately arrange the small piezoelectric elements 2 and realize a high density ink jet head.

EXPERIMENTAL EXAMPLE 1 Next, an experiment was conducted in which the above-described piezoelectric actuator 10 was applied to the ink jet head shown in FIG. 1 and the curvature radius R of the concave curved surface portion at the boundary between the substrate 1 and the piezoelectric element 2 was changed. .

The width (horizontal direction in the drawing) of the substrate 1 and the piezoelectric element 2 corresponding to the ink chamber 21 in FIG. 1 is 260 μm, the length (the depth direction in the drawing) is 3 mm, and the substrate 1 has a thickness of 20 μm.
The joining layer 5 was formed of low-melting glass having a thickness of 20 μm, and the piezoelectric element 2 was formed of PZT having a thickness of 70 μm.

By changing the blasting conditions,
The radius of curvature R of the concave curved surface portion 7 is 0 to 90 μm as shown in Table 1.
m. In addition, the measurement of the curvature radius R was obtained from a photograph whose section was enlarged 200 to 20,000 times by a scanning microscope. A voltage of 1 is applied to each piezoelectric actuator 10.
When a voltage of 00 V was applied, the maximum stress generated in the piezoelectric element 2 and the bonding layer 5 was calculated by computer simulation, and the displacement was measured at the same time.

The results are as shown in Table 1. From this result, when the radius of curvature R is increased to 0.5 μm or more, stress concentration is suppressed, and thus the stress generated in the piezoelectric element 2 and the bonding layer 5 tends to decrease to 110 MPa or less. On the other hand, if the radius of curvature R is larger than 80 μm, the area of the inactive portion of the piezoelectric element 2 fixed to the substrate 1 increases, so that the displacement of the substrate 1 tends to be reduced to 0.5 μm or less.

Also, from the processing ability of the blast,
It is difficult to provide a radius of curvature R of less than m, while the thickness of the piezoelectric element 2 that can be processed is limited to about 100 μm. When the curvature radius R becomes extremely large,
It becomes difficult to control the shape, which affects the driving characteristics of the piezoelectric element 2.

Considering the above conditions, in order to prevent stress concentration, obtain an appropriate displacement, and enable machining, the radius of curvature R of the concave curved surface portion 7 may be set to 0.5 to 80 μm.

[0066]

[Table 1]

Experimental Example 2 Next, the angle α of the side surface 2b of the piezoelectric element 2 with respect to the vertical
The relationship between the generated stress and the displacement when the temperature was changed was investigated.

In the same piezoelectric actuator 10 as described above, the curvature radius R of the concave curved surface portion 7 is set to 0, the width of the joint surface with the substrate 1 is fixed, and the angle α of the side surface 2 b of the piezoelectric element 2 with respect to the vertical direction is set. Table 2 shows the relationship between the displacement of the substrate 1 and the maximum stress generated in the actuator under each condition when is changed from 0 to 60 °.

As shown in Table 2, the maximum displacement increased with an increase in the angle α, and began to decrease after the angle α passed 45 °. On the other hand, the maximum generated stress gradually decreased. This is because when the side surface 2b of the piezoelectric element 2 is inclined, the piezoelectric element 2 tends to bend so as to be convex toward the substrate 1, and when the angle α becomes too large, the bonding area of the piezoelectric element 2 becomes large. , The area of the upper electrode 4 with respect to
It is considered that this is because the driving efficiency of the piezoelectric element 2 is reduced. The tendency of the stress to decrease during this period is considered to be caused by the decrease in the rigidity of the piezoelectric element 2 due to the slope and the decrease in the displacement later.

From the above results, the piezoelectric actuator 10
In order to reduce the stress generated at the same time and secure the deformation characteristics at the same time, the side surface 2b of the piezoelectric element 2 may be formed into a slope, and the angle α may be set to 45 ° or less.

[0071]

[Table 2]

EXPERIMENTAL EXAMPLE 3 Next, an experiment was conducted on the difference in workability of each material by blasting.

The surface of the smooth PZT plate forming the piezoelectric element 2 was masked with a photosensitive resin, leaving a square portion of 1 cm on a side, and 4 kgf of SiC fine powder having an average particle size of 6 μm was applied.
/ Pm ^{2 at} a gas pressure of 40 g / min.
After spraying the plate for 15 seconds to form a square hole, the four corners and the center depth of the formed square hole were measured with a dial gauge, the average of the difference was obtained, and the processing rate was calculated.

On the other hand, the same experiment as described above was carried out for stainless steel, alumina ceramics, and zirconia ceramics as the material forming the substrate 1.

The results are as shown in Table 3. From these results, the workability of stainless steel, alumina, and zirconia was PZ
It is inferior to T, indicating that the durability against blasting is high. Therefore, in the piezoelectric actuator 10 of the present invention, it is preferable to use a material such as stainless steel, alumina, zirconia or the like having higher durability against blast for the piezoelectric element 2 made of PZT as the substrate 1 so that the substrate can be used for blast processing. 1 can be suppressed as much as possible.

[0076]

[Table 3]

[0077]

As described above, according to the present invention, in a piezoelectric actuator in which a piezoelectric element having electrodes is bonded on a substrate via a bonding layer,
Since the concave curved surface portion having a radius of curvature of 0.5 μm to 80 μm is formed, even when stress generated by deformation of the piezoelectric element is applied to the bonding layer when the piezoelectric actuator is driven, the stress is provided on the side surface of the bonding layer. The concave curved surface portion allows the piezoelectric element to be satisfactorily dispersed in the bonding layer, effectively preventing peeling of the bonding layer, firmly bonding the piezoelectric element to the substrate, and obtaining a highly reliable piezoelectric actuator. It becomes possible. In addition, in this case, since the concave curved surface portion is formed on the bonding layer made of a relatively soft adhesive or various coupling agents, there is a problem that the bonding layer is chipped or cracked when the concave curved surface portion is formed. This is effectively prevented, and the productivity of the piezoelectric actuator is kept high.

Further, according to the present invention, after a plate-shaped or film-shaped piezoelectric element is bonded to a substrate, the piezoelectric element is masked, and the piezoelectric element in the non-masked portion is removed by high-precision fine blasting. By manufacturing the piezoelectric actuator from the step of processing the side surface of the joint between the piezoelectric element and the substrate into a concave curved surface, the piezoelectric element of any shape can be arranged on the substrate with high density and high precision, and damage during processing , And stable production becomes possible.

Further, by using the piezoelectric actuator of the present invention for an ink jet head, the density of the ink jet head can be increased.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an ink jet head using a piezoelectric actuator according to the present invention.

FIGS. 2A to 2C are perspective views for explaining a method of manufacturing a piezoelectric actuator according to the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a piezoelectric actuator according to the present invention.

FIG. 4 is a cross-sectional view showing an ink jet head using a conventional piezoelectric actuator.

[Explanation of symbols]

 1: substrate 2: piezoelectric element 3: mask 4: upper electrode 5: bonding layer 6: fine particle 7: concave curved surface portion 10: piezoelectric actuator

Claims (5)

(57) [Claims] A piezoelectric element having an electrode is bonded to a bonding layer on a substrate.
In the piezoelectric actuator formed by joining via the side surface of the bonding layer, the piezoelectric actuator, characterized in that the formation of the concave portions of the curvature radius 0.5 μm ~80μm. 2. The piezoelectric actuator according to claim 1 , wherein the side surface of the piezoelectric element forms an angle of 0 ° to 45 ° with respect to a vertical direction. 3. The piezoelectric element according to claim 1, wherein said piezoelectric element is lead zirconate titanate (PZT type), lead magnesium niobate (PMN type),
Lead nickel niobate (PNN system), lead manganese niobate, lead antimony stannate, lead zinc niobate, a piezoelectric ceramic to Nakano one or mainly of two or more of lead titanate, its thickness is 1 the piezoelectric actuator according to claim 1 or claim 2 characterized in that it is a μm ~100μm. 4. A ceramic, glass, stainless steel, titanium, or the like containing ZrO _{2 ,} Al ₂ O ₃ , and Si ₃ N ₄ as main components.
A pressure plate having electrodes on a substrate made of a metal material such as nickel, copper, aluminum alloy, or a highly elastic resin material
A piezoelectric actuator comprising an electric element;
The radius of curvature is 0.5 μm to 80 at the boundary between the piezoelectric element and the substrate.
A piezoelectric actuator having a concave curved surface portion of μm . 5. After bonding a plate-shaped or film-shaped piezoelectric element onto a substrate, a mask is formed on the piezoelectric element, and the non-masked piezoelectric element is removed by high-precision fine blasting. A method of manufacturing a piezoelectric actuator, comprising a step of processing a boundary portion with a thin substrate into a concave curved surface.