JPH08213667A - Manufacture of ceramics multilayered piezoelectric element - Google Patents

Abstract

PURPOSE: To facilitate position alignment at the time of polarizing, and manufacture an element of high flatness, by laminating and baking a plurality of green sheets on which electrodes and interlayer wirings are formed, polarizing an unified baked body by using surface electrodes electrically connected with the electrodes and the interlayer wirings, and working it into a product shape after polarizing. CONSTITUTION: An interlayer wiring is formed at a specified position on a formed green sheet, and a plurality of four-divided electrodes are formed by using conductive paste. A necessary number of green sheets are stacked in specified order. A green sheet laminate is obtained by heat pressing. The laminate is divided into four parts along division trenches formed in the green sheet laminate, and baked in a hermetic sheath. A sintered body is divided into an element 6, which is mounted on a recessed part 10 formed on a stage 9 of a polarizing equipment 8. Surface electrodes 1 electrically connected with electrodes and the interlayer wirings are position-aligned to terminal pins 11 for polarizing of the polarizing equipment 8, and polarizing process is performed. After the polarizing process is finished, outer diameter working is performed by using a cylinder grinding machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramics laminated piezoelectric element, and more particularly to a ceramics laminated piezoelectric element which can be easily aligned in the polarization step and can be manufactured with high flatness. The present invention relates to a method for manufacturing a body element.

[0002]

2. Description of the Related Art Conventionally, for example, in manufacturing a ceramics laminated piezoelectric element used as an element for an ultrasonic motor, a slurry obtained by mixing a piezoelectric powder with a binder or the like is extruded or a doctor blade. Method, etc., to form a thin green sheet, form a through hole in the green sheet, and fill the surface with an electrically conductive paste to form an interlayer wiring, and divide the plate into two or four electrodes. Is formed by a screen printing method using a conductive paste.

Next, the required number of the above-mentioned green sheets having electrodes and interlayer wirings are stacked in a predetermined order,
After applying appropriate temperature and pressure so that the multiple green sheets stacked by the binder in the green sheet are integrated, the dimensions are set to allow for firing shrinkage, for example, the product shape by shearing by means such as a punching press. For example, the above-mentioned green sheet in which a plurality of discs are integrated into a disc shape is processed.

Subsequently, the green sheet laminate processed into the product shape is fired in an airtight sheath,
After that, the disk-shaped ceramics sintered body 101 was removed as shown in FIG.
As shown in FIG. 5, the surface electrode 105, which is mounted in the circular recess 104 formed on the stage 103 of the polarization device 102 and is electrically connected to the electrodes and interlayer wiring existing inside the ceramic sintered body 101, and the polarization device 102. By aligning with the polarization terminal pin 106, the ceramic is polarized under appropriate polarization conditions (temperature, voltage, time) obtained by experiments,
A ceramic laminated piezoelectric element was manufactured.

[0005]

However, here,
In the above conventional manufacturing method, when the product shape is a disk shape during the polarization step, the disk-shaped element material 101 is replaced with the circular recess 104 of the polarization device 102 as shown in FIG. Will be aligned within
The positioning is a difficult task because the disk-shaped element material 101 easily rotates in the circular recess 104, and a lot of time is required for the polarization treatment operation.

Further, in the conventional manufacturing method, since the element material is processed into a product shape by shearing at the stage of the green sheet laminated body before firing, the stress and strain during the shearing process are outside the processed product. The residual ceramics remains in the peripheral area and warps occur in the ceramic sintered body after firing due to the residual stress and strain, and the strain generated by the subsequent polarization treatment also adds to the warp of the ceramic sintered body, and the finished ceramic laminated piezoelectric The flatness of the body element was poor.

The present invention has been made in view of the problems of the above-described conventional method for manufacturing a ceramics laminated piezoelectric element, and its purpose is to facilitate the alignment during the polarization process and to achieve flatness. An object of the present invention is to provide a method of manufacturing a ceramics laminated piezoelectric element capable of manufacturing a high-performance element.

[0008]

According to the present invention, in order to achieve the above-mentioned object, the step of processing into a product shape is performed after the polarization step. That is, the present invention includes a green sheet 2 having a plurality of surface electrodes and interlayer wirings 1 as shown in FIG. 1 and a plurality of green sheets 4 having four-divided electrodes and interlayer wirings 3 formed thereon. After stacking and integrating in a predetermined order, the green sheet laminated body 5 is fired, the obtained sintered body is divided into one element 6, and then the four-divided electrodes and the interlayers present inside are divided. The element 6 is polarized as shown in FIG. 3 by using the surface electrode 1 that is electrically connected to the wiring 3.
After that, a method of manufacturing a ceramics laminated piezoelectric element is processed into a product shape.

Further, the present invention provides a method for manufacturing a ceramics laminated piezoelectric element in which at least the above-mentioned polarization step is performed in a state of being temporarily processed into a rectangular plate shape including one or a plurality of elements.

[0010]

The above-described method for manufacturing a ceramic laminated piezoelectric element according to the present invention is characterized in that the step of processing into a product shape is performed after the polarization step. The operation will be described below.

In the conventional method for manufacturing a ceramics laminated piezoelectric element, as described in the above "Prior art", the laminated green sheets are processed into a product shape by shearing before the firing and polarization steps. It was

This step sequence uses the side surface of the stacked green sheets when the interlayer wiring is not formed by the conductive paste filled in the through holes in each green sheet before the green sheets are stacked. Since it is necessary to connect the internal electrodes with a conductive paste or the like, the process sequence must be followed.However, when the interlayer wiring is already formed together with the electrodes on the green sheet before lamination, this electrode and interlayer wiring Since it is possible to perform the polarization treatment before the product shape processing by using the surface electrode (the uppermost interlayer wiring) that conducts to the above, when such interlayer wiring is already formed on the laminated green sheet, However, it is not always necessary to follow this process sequence.

The greatest cause of warpage of the sintered ceramics after firing is that when the laminated green sheets are sheared into a product shape, the stress and strain during the shearing process are caused by the outer peripheral portion of the processed product. However, due to the residual stress and strain, the ceramic sintered body after firing is warped.

Further, the reason why the alignment at the time of polarization is made difficult is that the ceramics laminated piezoelectric element usually needs to be electrically connected to two or more surface electrodes at the time of polarization, and that element is used in the polarization device. Positioning needs to be done with considerable accuracy, but in the case of an element that has already been machined into a product shape during polarization, such as a disk, it will still rotate due to slight vibration even after being positioned in the polarization device. It was because I had to repeat the alignment many times.

Therefore, in the present invention, an interlayer wiring is formed in advance on the green sheet before lamination together with the electrodes, and the laminate having the electrodes and the interlayer wiring is processed into a product shape after the firing and polarization steps. By doing so, stress and strain will not occur in the green sheet before firing, and while solving the problem of warpage after firing,
Even if the product shape is a disk-shaped element, polarization is performed by, for example, a square plate shape before processing the product shape,
Positioning during polarization could be facilitated.

Further, in the present invention, since the element material is processed into a product shape after the polarization step, the finishing processing work requires more caution than the prior art performed at the stage of the soft green sheet. Since the ceramics used as a piezoelectric body have a hardness that is relatively easy to process even after firing, the ceramics can be processed without increasing the cost.
As a method of processing the product shape, laser processing or the like can be used in addition to mechanical processing such as grinding.

It is preferable that at least the polarization step before the product shape processing is performed in a state of being temporarily processed into a square plate shape, because the positioning during polarization can be surely performed. Here, in the manufacturing method according to the present invention, since the element material is processed into a product shape after the firing and polarization steps, any shape, such as a shape, which can be easily aligned in the polarization step, for example, The triangular plate shape other than the square plate shape or the pentagonal plate shape may be used. However, when considering how to make the shape, it is best to temporarily process the rectangular plate shape.

As a method of temporarily processing the element material into a square plate shape before the polarization step, as shown in FIG. 2, a green sheet laminated body 5 in which a necessary number of green sheets are integrated by thermocompression bonding is used to form a square sheet. A dividing groove 7 having an appropriate depth is formed on one side or both sides by using a metal blade or the like between a plurality of vertically and horizontally arranged elements 6 existing in a laminated body, for example, a portion to be formed into a plate shape. (Shown by a broken line), and is bent at that position before or after firing, for example, by hand to divide. The depth of the groove in this case depends on the thickness of the piezoelectric material used, the element material,
Alternatively, since it varies depending on the firing conditions, etc., it can be determined accurately by an experiment, but it is approximately 1/10 of the thickness of the element material.
It suffices to form a groove having a certain depth. In addition, the grooving process for forming the divided grooves is performed by vertically pressing a blade against the laminated body, or by so-called pull-cutting, push-cutting, or the like. Strippers for pressing the laminated body are attached to both sides of the blade, and the stripper is used under proper conditions of the force for pushing the laminated body and the timing of vertical driving of the blade.

Of course, it is not necessary to form the dividing groove with the metal blade as described above, but the groove may be formed with the ceramic blade or the laser beam.
Also, firing the laminated body with grooves as it is, and then dividing along the grooves will result in the cleanest fracture surface,
Further, since a plurality of elements can be handled simultaneously before firing, workability is improved. Of course, all may be divided along the groove before firing. Further, the sintered body which is the element material may be provisionally processed into a rectangular plate shape by dicing or laser processing after firing the laminated body without forming the above groove in the laminated body. Results in poor workability and high processing cost.

In the event that the square plate shape is temporarily processed, stress strain remains in the outer peripheral portion of the processed product, and even if the ceramic sintered body after firing is warped due to this residual stress. The outer peripheral warp can be cut off during the subsequent processing into the product shape, and is not a problem.

In the method for manufacturing a ceramics laminated piezoelectric element described above, the step of working into the product shape is performed after the firing and polarization steps, whereby the element after firing is warped and the alignment during polarization is performed. It is possible to simultaneously solve the problem of the conventional technique of difficulty in manufacturing, and to provide a method for manufacturing a ceramics laminated piezoelectric element that can be easily preliminarily processed and can be improved in firing workability.

[0022]

[Examples and Comparative Examples] Examples of the present invention described above will be described below.
The details will be described together with a comparative example.

Example First, a slurry obtained by mixing a polyacrylic binder with PZT-based piezoelectric powder was molded into a green sheet having a film thickness of 150 μm by the doctor blade method.

Next, a plurality of through-holes having a diameter of 150 μm are formed at predetermined positions of the molded green sheet, and the through-holes are filled with a conductive paste by a screen printing method to form an interlayer wiring. A plurality of quadrant electrodes were formed on the surface of the green sheet by using the conductive paste by the screen printing method. Ag is used as the conductive material.
-Pd was used.

Next, the required number of sheets (here, 25 sheets) of the green sheets on which electrodes and interlayer wirings are printed are piled up in a predetermined order, and hot pressed at 90 ° C. and 250 kg / cm ² , for 5 minutes, A green sheet laminate was obtained. The green sheet laminate has a size of 100 mm in length and width, and there are arranged a total of 36 parts, which are laminated piezoelectric elements having a diameter of 13 mm, in 6 rows and 6 columns (see FIG. 1). However, in FIG. 1, only the inter-layer wiring to be the surface electrode and the four-divided electrode are shown, and the other inter-layer wiring is omitted.

Subsequently, grooving is performed between the respective element parts of the green sheet laminate by using a metal blade having a thickness of 0.2 mm, and the dividing groove is formed on one surface of the laminate with a depth of 0. Three
mm (see FIG. 2). The dividing groove was formed by pressing a metal blade vertically against the plate surface of the laminate.

Next, the laminate before firing was divided into four along the dividing grooves, and the obtained laminate having a length and width of 50 mm was fired in an airtight sheath. The firing conditions were a temperature of 1200 ° C. and a time of about 2 hours.

After firing, the sintered body was divided into the respective element portions along the dividing grooves, and each of the obtained 36 rectangular plate-shaped sintered bodies, each element 6, is shown in FIG. As shown, the surface electrode 1 is mounted in the recess 10 formed on the stage 9 of the polarization device 8 and is electrically connected to the electrodes and the interlayer wiring existing inside the element 6, and the polarization terminal pin 11 of the polarization device 8. Were aligned, and a DC voltage of 500 V was applied for 30 minutes in an air atmosphere at 140 ° C. to perform polarization treatment.

After the polarization treatment is completed, since the laminated piezoelectric element of this embodiment is used in a disc shape, an outer diameter processing for cutting off the corners is performed using a cylindrical grinder, and 36 discs are formed. A piezoelectric ceramic laminated piezoelectric element was obtained.

In the obtained disk-shaped ceramics laminated piezoelectric element, all 36 were polarized, and when the warp of the element was measured, all of them were 10 μm or less and had good flatness. It was an element.

Separately, in the above-mentioned embodiment, four pieces of 50 mm long and wide sintered bodies including nine element parts were used in a state where they were not divided and were subjected to nine polarization treatments. The warp of each of the 36 disc-shaped ceramics laminated piezoelectric elements obtained by performing polarization processing, dividing each element into parts, and subjecting each element to outer shape processing in the same manner as in the above embodiment was measured. I just did
All of the devices had a thickness of 20 μm or less and had good flatness.

-Comparative Example- As a comparative example, a disc-shaped ceramic laminated piezoelectric element was formed by shearing an outer diameter into a disc shape, which is the product shape, before the firing step, and then firing and polarization. Manufactured. The only difference from the example is the above, and the materials used and other process conditions were the same as in the example.

In the obtained disk-shaped ceramics laminated piezoelectric element, 3 out of 36 polarization defects occurred due to the misalignment of the polarization terminal pins during the polarization treatment, and the alignment during polarization was not achieved. It was difficult. Moreover, when the warpage of the elements was measured, 100 μ was obtained for all the elements.
A large warp of m to 130 μm occurred.

[0034]

As described above, the method of manufacturing a ceramics laminated piezoelectric element according to the present invention is characterized in that the step of finally processing into a product shape is performed after the firing and polarization steps. Therefore, by adopting this method, it becomes possible to easily manufacture an element having a high degree of flatness in alignment during the polarization step, and
Preliminary processing can be performed easily, and it is also possible to perform firing and polarization in an integrated state without firing or polarizing each piece at the time of firing and polarization. Have.

[Brief description of drawings]

FIG. 1 is a conceptual perspective view showing a green sheet laminating step in a manufacturing process of a ceramics laminated piezoelectric element according to the present invention.

FIG. 2 is a conceptual plan view and a side view showing a state in which a groove is formed in a laminated body of green sheets during a manufacturing process of a ceramics laminated piezoelectric element according to the present invention.

FIG. 3 is a conceptual perspective view showing a polarization step in the manufacturing process of the ceramics laminated piezoelectric element according to the present invention.

FIG. 4 is a conceptual perspective view showing a polarization process in the manufacturing process of the conventional ceramics laminated piezoelectric element.

[Explanation of reference numerals] 1 surface electrode and interlayer wiring 2 green sheet 3 four-divided electrode and interlayer wiring 4 green sheet 5 green sheet laminate 6 element 7 dividing groove 8 polarization device 9 polarization device stage 10 square formed on stage Recessed portion 11 Polarization terminal pin for polarization device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Maruyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Nobuyuki Kojima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (4)

[Claims] 1. A plurality of green sheets on which electrodes and interlayer wirings are formed are laminated in a predetermined order, the laminated body is fired to be integrated, and the obtained sintered body is present therein. A method for manufacturing a ceramics laminated piezoelectric element, characterized in that polarization is performed using the above-mentioned electrodes and surface electrodes that are electrically connected to the interlayer wiring, and then the product is processed into a product shape. 2. The ceramic laminated piezoelectric element according to claim 1, wherein at least the polarization step is performed in a state of being temporarily processed into a rectangular plate shape including one or a plurality of elements. Manufacturing method. 3. The tentative working comprises first grooving in the state of the green sheet laminate before firing, and after the grooving, dividing the laminate along the groove portions to obtain 1
3. The method for manufacturing a ceramics laminated piezoelectric element according to claim 2, wherein the step is temporarily processed into a rectangular plate shape including one or a plurality of elements. 4. The preliminary processing is performed by firing a laminate of green sheets divided into a square plate shape including a plurality of elements in a square plate shape, and then further sintering along the groove portions. 4. The method for manufacturing a ceramics laminated piezoelectric element according to claim 3, wherein the ceramics laminated piezoelectric element is temporarily processed into a square plate shape including one or a plurality of elements by dividing.