JP2001129990A - Laminate structure using piezoelectric ceramic element and a method for manufacturing this ceramic element and ink jet recording head using this ceramic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a securely bonded laminate structure which is free from the peeling of an adhesive interface even when fatigue due to repeated strain generated by the displacement of a piezoelectric ceramic element is applied. SOLUTION: A piezoelectric ceramic element 2 and a member 5 for lamination are superposed on each other by applying a heat-curable adhesive 6 which a viscosity of 1.5 P or less at 40-60 deg.C to an interface between the element 2 and the member 5, and are thermally cured under reduced pressure. Thus the laminate structure 1 using the piezoelectric ceramic element 2 is obtained which has a thickness (t) of 1.5 μm or less of the adhesive 6 and an occupancy area rate of 5% of less of air bubbles present in the adhesive face of the adhesive layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an actuator,
The present invention relates to a bonding structure using a piezoelectric ceramic body formed by bonding a piezoelectric ceramic body and a member to be bonded, such as a diaphragm and a buzzer, with a thermosetting adhesive, a method for manufacturing the same, and an ink jet recording head using the same. .

[0002]

2. Description of the Related Art Conventionally, actuators, diaphragms,
For a buzzer or the like, a bonded structure in which a bonded member as a reinforcing material or a fixing material is bonded to a piezoelectric ceramic body via an adhesive layer made of a thermosetting adhesive is used.

[0003] In order to manufacture such a bonded structure, an insulating ceramic such as alumina, zirconia, or forsterite, a piezoelectric ceramic, or a metal as a member to be bonded, or a metal is screen-printed or offset-printed.
When a paste-like thermosetting adhesive is applied by a method such as a dispenser, the piezoelectric ceramic bodies are stacked, and heat-cured while being pressed at normal pressure.

In recent years, with the spread of multimedia, ink-jet printing apparatuses for printing various types of information on a recording medium have been rapidly spreading, and actuators of an ink-jet recording head mounted on the printing apparatus have been rapidly spreading. The above-mentioned attachment structure is used.

FIG. 4 shows an example of a conventional ink jet recording head. As shown in FIG.
A plurality of partition walls 22 are arranged side by side, and a space between each partition wall 22 is formed as an ink flow path 27.
A flow path member 21 made of piezoelectric ceramics provided with 6;
The drive electrodes 23 formed on both side surfaces of the partition 22 and the ink discharge holes 25 that are bonded to the top surface of the partition 22 via an adhesive layer made of a thermosetting adhesive and communicate with the flow paths 27 are formed. In some cases, the flow path member 21 was divided at the center in the thickness direction and bonded via an adhesive layer made of a thermosetting adhesive. Note that each of the piezoelectric ceramics 29a, 29
b is polarized in the direction of the arrow. 28 in the figure.
Is a lead line of the driving electrode 23.

In order to discharge ink droplets by the ink jet recording head, a current is applied to the drive electrode 23 of the partition 22 to be displaced, and the partition 22 is bent and displaced in a "-" shape, thereby causing the displacement of the partition 22 (not shown). The ink introduced into the flow path 27 from the ink tank via the ink supply hole 26 is pressurized to eject ink droplets from the ink ejection hole 25.

[0007]

In the case of forming a bonded structure using a piezoelectric ceramic body, a thermosetting adhesive generally used as an adhesive layer is 40 to 6%.
Since the viscosity at 0 ° C. is high, the composition is applied in a state where the viscosity is reduced by further applying heat, and after the piezoelectric ceramic body and the member to be bonded are thermocompression-bonded, heat treatment is applied to cure the piezoelectric ceramic body. If heat above the Curie temperature is applied for a long time, the piezoelectric properties of the piezoelectric ceramic body will deteriorate, making it difficult to apply the heat necessary to lower the viscosity of the thermosetting adhesive. Since air bubbles remain therein and the thickness of the adhesive layer cannot be reduced, the adhesive strength between the piezoelectric ceramic body and the member to be pasted cannot be increased.

When a thermosetting adhesive is cured by heat, a reactive gas is generated. However, if the thickness of the adhesive layer is large, the reactive gas is difficult to escape, so that the reactive gas remains as bubbles in the adhesive layer. The adhesion strength was further reduced.

[0009] Therefore, when this pasted structure is used for an actuator, a diaphragm, a buzzer, or the like, a problem that the adhesive layer is peeled off due to repeated fatigue due to displacement of the piezoelectric ceramic body and performance is greatly deteriorated. was there.

[0010] Further, the bonding structure is used to form an adhesive portion between the partition wall 22 and the nozzle plate 24 constituting the ink jet recording head and the piezoelectric ceramics 29 a and 2 forming the partition wall 22.
When the partition walls 22 are displaced, the flow passages 27 are separated from each other and the adjacent flow passages 27 communicate with each other.
Since the internal pressure is absorbed, there has been a problem that the discharge speed and the discharge amount of ink droplets are reduced.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a bonding method using a piezoelectric ceramic body formed by bonding a member to be bonded to a piezoelectric ceramic body via an adhesive layer made of a thermosetting adhesive. In the structure, the thickness of the adhesive layer is 1.5 μm or less, and the occupied area ratio of bubbles existing on the adhesive surface of the adhesive layer is 5% or less.

Further, according to the present invention, in order to manufacture a bonding structure using the above-mentioned piezoelectric ceramic body, the viscosity at 40 to 60 ° C. between the piezoelectric ceramic body and the member to be bonded is 1.5 poise or less. After a certain thermosetting adhesive is applied and laminated, thermocompression bonding is performed under reduced pressure, followed by heat curing.

Further, according to the present invention, a plurality of partition walls are juxtaposed,
A space between each partition serves as an ink flow path, and at least the partition includes a flow path member made of piezoelectric ceramics, and a nozzle plate bonded to the top surface of each partition via an adhesive layer made of a thermosetting adhesive. In the ink jet recording head, the thickness of the adhesive layer for adhering the piezoelectric ceramic forming the partition and the nozzle plate as the member to be adhered is set to 1.5.
μm or less, and the occupied area ratio of bubbles existing on the bonding surface of the bonding layer is 5% or less.

According to the present invention, in the above-mentioned ink jet recording head, the partition walls are divided along the longitudinal direction and are bonded through an adhesive layer made of a thermosetting adhesive. 5 μm or less, and the occupied area ratio of bubbles existing on the adhesive surface of the adhesive layer is 5% or less.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a partially broken perspective view showing an example of a pasted structure using a piezoelectric ceramic body according to the present invention.

The bonded structure 1 has electrode layers 3 on upper and lower surfaces.
The plate-shaped piezoelectric ceramic body 2 on which the substrate 4 is formed and the plate-shaped member to be bonded 5 are bonded via an adhesive layer 6 made of a thermosetting adhesive, and the thickness t of the adhesive layer 6 is 1.5 μm. Besides, the occupied area ratio of bubbles existing on the bonding surface of the bonding layer 6 with the piezoelectric ceramic body 2 and the member 5 to be bonded is set to 5% or less.

That is, in order to increase the adhesive strength, the adhesive layer 6
It is better to make the thickness t of the adhesive layer 6 as small as possible. However, if the thickness t of the adhesive layer 6 exceeds 1.5 μm, the amount of bubbles existing in the adhesive layer 6 increases, and the occupancy of the bubbles existing on the adhesive surface increases. This is because the area ratio cannot be reduced to 5% or less.

The occupation area ratio of bubbles existing on the bonding surface of the bonding layer 6 with the piezoelectric ceramic body 2 and the member 5 to be attached is set to 5% or less because the occupation area ratio of bubbles on the bonding surface is 5%. When the bonding structure 1 is used as an actuator, a diaphragm, a buzzer, or the like, when the bonded structure 1 is used as an actuator, a diaphragm, a buzzer, or the like, repeated fatigue due to displacement of the piezoelectric ceramic body 2 occurs. This is because peeling occurs at each bonding interface.

In the present invention, the thickness t of the adhesive layer 6
Means the average thickness, cuts the bonded structure 1, takes an electron micrograph of the cut surface, measures the thickness at three points at the center and both ends of the cut surface from the photograph, and calculates the average value. And

The occupied area ratio of the air bubbles present on the bonding surface is the ratio of the air bubbles occupying the bonding surface between the piezoelectric ceramic body 2 and the member 5 to be attached.
Using an ultrasonic microscope (HSAM manufactured by Hitachi Construction Machinery) having an ultrasonic probe of 0 MHz, an image obtained by setting the measurement visual field to 6 × 6 mm is image-processed, and the area occupied by bubbles existing in the measurement visual field with respect to the area of the measurement visual field Is expressed as a percentage.

Thus, when the current supply and cutoff between the electrode layers 3 and 4 of the bonding structure 1 shown in FIG. 1 are repeated, the piezoelectric ceramic body 2 tends to expand and contract in a direction perpendicular to the polarization (thickness) direction. On the other hand, since the movement is regulated by the member to be pasted 5, the pasted structure 1 is bent and displaced in the polarization (thickness) direction. Even when repeated fatigue due to bending displacement is applied, the bonding interface is not peeled off because it is firmly bonded, and the thickness of the bonding layer 6 is small,
Since a large bending displacement can be obtained without the displacement force of the piezoelectric ceramic body 2 being absorbed by the adhesive layer 6, the piezoelectric ceramic body 2 can be suitably used as an actuator, a diaphragm, a buzzer, or the like.

As the thermosetting adhesive for forming the adhesive layer 16, an epoxy-based adhesive, a polyimide-based adhesive, a phenol-based adhesive, or the like can be used. Among these, an epoxy-based adhesive is preferable. is there.

When an epoxy-based adhesive is used, it is preferable to use one having an average molecular weight of 400 or more. By setting the average molecular weight to 400 or more, the curing time of the adhesive can be shortened and the curing temperature of the adhesive can be reduced. Therefore, the piezoelectric characteristics of the piezoelectric ceramic body 12 are not deteriorated. In addition, since the hard adhesive layer 16 can be formed,
In the case where the bonding structure 11 is subjected to grinding, the bonding layer 1
6 can be prevented from being roughened and peeling off at the joint interface.

The piezoelectric ceramic body 2 used in the bonding structure 1 is mainly composed of lead zirconate titanate (PZT type), lead magnesium niobate (PMN type), lead nickel niobate (PNN type) or the like. Piezoelectric ceramics can be used, and a material such as metal, glass, ceramics or the like can be used as the member 5 to be adhered to the piezoelectric ceramic body 2. For example, in the case of metal, tin, aluminum, copper, nickel, titanium, Iron, molybdenum, alloys containing these, and stainless steel can be used. Examples of ceramics include insulating ceramics mainly composed of alumina, zirconia, forsterite, silicon nitride, and the like, and zirconium titanate. Lead oxide (PZT type), lead magnesium niobate (PMN type),
A piezoelectric ceramic containing lead nickel niobate (PNN-based) or the like as a main component can be used. However, in order to enhance the adhesive strength, it is preferable to use a material having a difference in thermal expansion from the piezoelectric ceramic body 2 as small as possible.

Next, a method of manufacturing the attachment structure 1 shown in FIG. 1 will be described.

First, silver, gold, platinum, nickel, copper, aluminum,
After forming the electrode layers 3 and 4 by depositing a metal such as tin by means of vapor deposition, plating, baking or the like, a polarization process is performed in the thickness direction of the piezoelectric ceramic body 2.

On the other hand, a plate-shaped member to be pasted 5 is prepared,
When a paste-like thermosetting adhesive is applied to the bonding surface of the member 5 or the piezoelectric ceramic body 2 by means of a screen printing method, an offset printing method, a dispenser, or the like, the other piezoelectric ceramic body 2 or the The sticking members 5 are overlapped, and at this time, 40 to 40
It is important to use one having a viscosity at 60 ° C. of 1.5 poise or less. That is, when the viscosity of the thermosetting adhesive at 40 to 60 ° C. is higher than 1.5 poise, the thickness t of the adhesive layer 6 is set to 1.5 μm or less unless heat near the Curie temperature of the piezoelectric ceramic body 2 is applied. Because they cannot do it.

In applying the thermosetting adhesive to the piezoelectric ceramic body 2 or the member 5 to be attached, the bonding strength can be increased by applying a coupling agent in advance.

Thereafter, the laminated body of the piezoelectric ceramic body 2 and the bonded structure 5 is thermocompression-bonded while applying pressure. At this time, it is important that the treatment is performed under reduced pressure. That is, the thermosetting adhesive paste having the above-mentioned viscosity is thermocompressed under reduced pressure to remove bubbles in the adhesive layer 6 without damaging the piezoelectric ceramic body 2 which is not so high in strength. The occupied area ratio of bubbles existing on the bonding surface of the layer 6 can be set to 5% or less. In addition, specifically, it is preferable to carry out under reduced pressure of 5 kPa to 21 kPa.

Next, by heating and curing at 100 to 150 ° C., the thickness t of the adhesive layer 6 can be reduced to 1.5 μm or less, and the occupied area ratio of bubbles existing on the bonding surface can be reduced to 5% or less. High-reliability bonding structure 1
It can be manufactured with good yield.

Next, an application example in which the bonding structure using the piezoelectric ceramic body according to the present invention is used for an ink jet recording head will be described with reference to FIG.

In this ink jet recording head, a plurality of partition walls 12 are arranged in parallel, an ink flow path 17 is provided between the partition walls 12, and a flow path member 11 having an ink supply hole 16 is provided at the bottom of each flow path 17. And a nozzle plate 14 having an ink discharge hole 15 connected to each flow path 17 and bonded to the top surface of the partition 12 via an adhesive layer made of a thermosetting adhesive. On the upper half of the surface, drive electrodes 13 are formed along the longitudinal direction, and each drive electrode 13 is energized via a lead wire 18 laid on one end side of the flow path member 11. It has become.

The flow path member 11 has two piezoelectric ceramic bodies 19a and 19b bonded at the center in the thickness direction via an adhesive layer made of a thermosetting adhesive. Each of the piezoelectric ceramic bodies 19a and 19b is In the thickness direction, polarization treatment is performed in the directions of the arrows.

The thickness of the adhesive layer for bonding the piezoelectric ceramic bodies 19a and 19b constituting the flow path member 11 and the thickness of the adhesive layer for bonding the partition wall 12 and the nozzle plate 14 are each 1.5 μm or less. At the same time, the occupied area ratio of bubbles existing on the bonding surface of the bonding layer is set to 5% or less.

To print on a recording medium (not shown) using this ink jet recording head, an ink such as a pigment type oil-based ink, a water-based dye ink, or an ultraviolet curable ink is supplied from the ink supply hole 16 to each flow path 17. 3A, for example, as shown in FIG.
When a negative voltage is applied to the driving electrodes 13h and 13i, and a positive voltage is applied to the driving electrodes 13a, 13d, 13g and 13j, the partition wall 12 is deformed by shear mode deformation.
a and 12b are bent toward the flow path 17a, and the partition walls 12d and 12e are bent toward the flow path 17d. Therefore, the ink filled in the flow paths 17a and 17d is pressurized to form the ink ejection holes. 15 ejects ink droplets.

Next, the driving electrodes 13a to 13d, 1
When the power supply to 3g to 13j is cut off, the partitions 12a, 12b, 12d, and 12e, which have been bent and displaced, return to their original shapes by the elastic action, and the pressure in the flow paths 17a and 17d is reduced. The introduction of the ink is started, and the driving electrodes 13a to 13
When a voltage is applied in the opposite direction to d, 13g to 13j, the partition walls 12a and 12b are bent outwardly with respect to the flow path 17a, respectively, as shown in FIG.
Since the partition walls 12d and 12e are each bent outwardly with respect to the flow path 17d, the pressure inside the flow paths 17a and 17d is further reduced, and the ink is filled. When the power supply to the driving electrodes 13a to 13d and 13g to 13j is cut off, the partition walls 12a, 12b, 12
The d and 12e return to the original shape by the elastic action and enter the next ink ejection stage. By repeating these operations sequentially, the ink droplets are continuously ejected from the ink ejection holes 15. Has become.

The ink jet recording head has a piezoelectric ceramic body 19a,
The thickness of the adhesive layer for bonding the 19b to each other and the thickness of the adhesive layer for bonding the top surface of the partition wall 12 to the nozzle plate 14 are each 1.5 times.
μm or less, and since the occupied area ratio of bubbles existing on the bonding surface of each bonding layer is set to 5% or less, they are air-tightly and firmly bonded, and do not peel even when the partition wall 12 is bent and displaced. Since a pressure corresponding to the amount of displacement can be generated in the flow path 17, it is possible to prevent a drop in the ejection speed and ejection amount of ink droplets over a long period of time, and to provide a highly reliable ink jet recording head. Can be.

The present invention is not limited to the bonding structure 1 shown in FIG. 1 and the ink jet recording head shown in FIG. 2, and it is possible to make improvements and modifications without departing from the scope of the present invention. Needless to say.

[0040]

(Example 1) Here, a bonded structure using a piezoelectric ceramic body in which the thickness of the adhesive layer and the occupied area ratio of bubbles existing on the adhesive surface were made different from each other was manufactured. An experiment was conducted to examine the presence or absence of breakage and the presence or absence of peeling after the durability test.

In the experiment, a piezoelectric ceramic body having a thickness of about 1.0 mm and containing lead zirconate titanate as a main component was prepared, and lapping was performed using silicon carbide abrasive grains.
After the thickness is reduced to 0.7 mm, the upper and lower surfaces of the piezoelectric ceramic body are washed, and thereafter, an electrode layer made of a silver-palladium alloy is formed by a sputtering method. went.

Next, after the surface of the electrode layer of the piezoelectric ceramic body is treated with a coupling agent having an epoxy group, an epoxy adhesive paste having different viscosities and average molecular weights is applied by an offset printing method. After being applied and stacking the members to be bonded made of titanium, the members are placed in a vacuum chamber, and press-bonded by applying heat while applying heat in a non-reduced atmosphere and a reduced-pressure atmosphere (8 kPa).
By applying a heat treatment at a temperature of 150 ° C. for about 1 hour, the epoxy-based adhesive was cured to produce a bonded structure in which the thickness of the adhesive layer and the occupied area ratio of bubbles existing on the adhesive surface were different.

In the obtained bonded structure, the occupied area ratio of the air bubbles existing on the bonding surface of the bonding layer was 100 M
The image obtained by an ultrasonic microscope (HSAM manufactured by Hitachi Construction Machinery Co., Ltd.) having an ultrasonic probe of 1 Hz is calculated by image processing, and the adhesive structure is cut to measure the thickness of the adhesive layer. Electron micrographs were taken to measure the thickness at the center and both ends, and the average value was taken as the thickness of the adhesive layer.

Further, after applying voltage to the obtained bonded structure and displacing it 100 million times, the presence or absence of peeling was confirmed using the ultrasonic microscope.

The production conditions and results are as shown in Table 1.

The thickness of the piezoelectric ceramic body is set to 0.5 μm.
A similar structure was also manufactured, and a similar experiment was performed.

[0047]

[Table 1]

As can be seen from Table 1, the thickness of the piezoelectric ceramic body was reduced by setting the thickness of the adhesive layer to 1.5 μm or less and the area occupied by bubbles existing on the bonding surface of the adhesive layer to 5% or less. Even if it is thin, it will not be damaged during production,
In addition, since there was no peeling even when the bonded structure was repeatedly bent and displaced, both could be firmly bonded.

The viscosity at 40-60 ° C. is 1.5
By using a thermosetting adhesive having a poise or less and performing thermocompression bonding under reduced pressure, the thickness of the adhesive layer in the bonded structure can be reduced to 1.5 μm or less, and bubbles existing on the adhesive surface of the adhesive layer Can be reduced to 5% or less. (Example 2) In addition, after cutting the bonded structure shown in Table 1 with a diamond saw, the bonding surface was observed with an electron microscope, and an experiment was conducted to check for the presence or absence of peeling at the bonding interface.

The results are as shown in Table 2.

[0051]

[Table 2]

As a result, the thickness of the adhesive layer was 1.5 μm or less, and the area occupied by bubbles existing on the adhesive surface of the adhesive layer was 5%.
It was found that by using an epoxy adhesive having a molecular weight of 400 or more and a molecular weight of 400 or more, a strong bonded structure without peeling even when subjected to grinding was obtained.

From this, it can be seen that when an epoxy adhesive is used as the adhesive layer, it is preferable to use one having an average molecular weight of 400 or more in order to obtain a strong adhesive force.

[0054]

As described above, according to the present invention, there is provided a bonded structure using a piezoelectric ceramic body formed by bonding a member to be bonded to a piezoelectric ceramic body via an adhesive layer made of a thermosetting adhesive. A thermosetting adhesive having a viscosity of 1.5 poise or less at 40 to 60 ° C. is applied and laminated between the piezoelectric ceramic body and the member to be bonded, followed by thermocompression bonding under reduced pressure, and then heat curing. And the thickness of the adhesive layer is 1.5 μm
By setting the occupied area ratio of bubbles existing on the bonding surface of the bonding layer to 5% or less, even if repeated fatigue due to displacement of the piezoelectric ceramic body is applied, there is no separation at the bonding interface, and the bonding is firm. Thus, a bonded structure can be obtained.

Further, according to the present invention, there is provided a flow path member in which a plurality of partitions formed by forming two piezoelectric ceramic bodies via an adhesive layer made of a thermosetting adhesive are arranged in parallel, and an ink flow path is provided between the partitions. And a nozzle plate bonded to the top surface of each partition via a bonding layer made of a thermosetting adhesive, wherein the bonding layer between the piezoelectric ceramic bodies forming the partition, the partition and the nozzle are provided. Since the thickness of the adhesive layer with the plate is 1.5 μm or less, and the occupied area ratio of the bubbles existing on the adhesive surface of the adhesive layer is 5% or less, the ink droplet ejection speed and ejection amount decrease over a long period of time. And a highly reliable inkjet recording head can be provided.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing an example of an attaching structure using a piezoelectric ceramic body according to the present invention.

FIG. 2 is a partially cutaway perspective view showing an example in which an attachment structure using a piezoelectric ceramic body according to the present invention is applied to an ink jet recording head.

FIGS. 3A and 3B are diagrams for explaining the driving principle of the ink jet recording head in FIG. 2;

FIG. 4 is a partially broken perspective view showing an example in which a pasting structure using a piezoelectric ceramic body is applied to an ink jet recording head.

[Explanation of symbols]

1: Pasting structure 2: Piezoelectric ceramic body 3, 4: Electrode layer 5: Member to be pasted 6: Adhesive layer 11, 21: Flow path member 12, 22: Partition wall 13, 2
3: Drive electrodes 14, 24: Nozzle plate 15, 25: Ink ejection hole 16, 26: Ink supply hole 17, 27: Channel 18,
28: Leader

Claims (4)

[Claims] 1. A bonding structure in which a member to be bonded is bonded to a piezoelectric ceramic body via a bonding layer made of a thermosetting adhesive, the bonding layer having a thickness of 1.5 μm or less, and A bonding structure using a piezoelectric ceramic body, wherein an occupied area ratio of bubbles existing on an adhesion surface of the layer is 5% or less. 2. The method according to claim 1, further comprising:
2. The piezoelectric material according to claim 1, wherein a thermosetting adhesive having a viscosity of not more than 1.5 poise at 40 to 60 [deg.] C. is applied, laminated, thermocompression-bonded under reduced pressure, and then heat-cured. A method for manufacturing a bonded structure using a ceramic body. 3. A plurality of partition walls are arranged in parallel, a space between each partition wall is used as an ink flow path, at least the partition wall is made of a piezoelectric ceramic, and a thermosetting adhesive is provided on a top surface of each partition wall. In an ink jet recording head comprising a nozzle plate bonded through an adhesive layer, the thickness of the adhesive layer is 1.5 μm or less, and the occupied area ratio of bubbles existing on the adhesive surface of the adhesive layer is 5% or less. An ink jet recording head, characterized in that: 4. The partition wall is divided along a longitudinal direction and is bonded through an adhesive layer made of a thermosetting adhesive, the thickness of the adhesive layer is 1.5 μm or less, and the thickness of the adhesive layer is 4. The ink jet recording head according to claim 3, wherein an occupied area ratio of bubbles existing on the bonding surface is 5% or less.