Multilayer piezoelectric ceramic full electrode structure and its manufacturing process

Abstract

The present invention discloses a laminated piezoelectric ceramic full electrode structure, including an upper insulating layer, an external positive electrode layer, an external negative electrode layer, a lower insulating layer, a piezoelectric dielectric layer, an internal positive electrode layer and an internal full negative electrode layer. The manufacturing process is also disclosed, wherein multiple piezoelectric dielectric films are laminated according to a designed thickness and hot pressed to form a lower insulating layer, and an internal positive electrode layer is printed on the lower insulating layer and dried. After the drying is completed, a piezoelectric dielectric film is laminated on the internal positive electrode layer and hot pressed. After the hot pressing is completed, an internal full negative electrode layer is printed on the piezoelectric dielectric film and dried again. In the process described above, the internal positive electrode layer, the piezoelectric dielectric layer and the internal full negative electrode layer are repeatedly laminated, and the layers are laminated to a specified height according to the design requirements, and an upper insulating layer is laminated on the top.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric ceramics, and in particular relates to a laminated piezoelectric ceramic full-electrode structure and a manufacturing process thereof. Background Art

[0002] Piezoelectric ceramics are information functional ceramic materials that can convert mechanical energy and electrical energy into each other - piezoelectric effect. In addition to piezoelectricity, piezoelectric ceramics also have dielectric properties and elasticity, and have been widely used in medical imaging, acoustic sensors, acoustic transducers, ultrasonic motors, etc. Piezoelectric ceramics are made by using the fact that under the action of mechanical stress, the internal positive and negative charge centers are relatively displaced and polarized, resulting in the appearance of bound charges of opposite signs on the surfaces of both ends of the material, i.e., piezoelectric effect. Piezoelectric ceramics have sensitive characteristics. They are mainly used to manufacture ultrasonic transducers, hydroacoustic transducers, electroacoustic transducers, ceramic filters, ceramic transformers, ceramic frequency discriminators, high-voltage generators, infrared detectors, surface acoustic wave devices, electro-optical devices, ignition and detonation devices, and piezoelectric gyroscopes. In addition to being used in high-tech fields, they serve people more in daily life.

[0003] However, during the use of existing laminated piezoelectric ceramics, the external insulating layer (non-electrode output surface) has no piezoelectric properties and no deformation. The effective piezoelectric ceramics are deformed under the action of voltage, which drives the external insulating layer to stretch. The insulating layer constrains the internal deformation, causing the output force of the piezoelectric ceramics to decrease; and during the repeated deformation process, the insulating layer is repeatedly stretched to produce fatigue damage, which reduces the service life of the piezoelectric ceramics. Summary of the invention

[0004] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a laminated piezoelectric ceramic full-electrode structure and a manufacturing process thereof.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A stacked piezoelectric ceramic full-electrode structure comprises an upper insulating layer, an external positive electrode layer, an external negative electrode layer, a lower insulating layer, a piezoelectric dielectric layer, an internal positive electrode layer and an internal full-negative electrode layer, wherein the upper insulating layer and the lower insulating layer are respectively arranged on the upper and lower end surfaces, the external positive electrode layer and the external negative electrode layer are arranged on two side surfaces opposite to each other, the external positive electrode layer is connected to the internal positive electrode layer, the external negative electrode layer is connected to the internal full-negative electrode layer, the internal positive electrode layer and the internal full-negative electrode layer are arranged alternately, and the piezoelectric dielectric layer is arranged between the internal positive electrode layer and the internal full-negative electrode layer.

[0007] It is further defined that the external positive electrode layer and the external negative electrode layer are screen-printed silver paste, which are sintered to form electrodes.

[0008] It is further defined that the piezoelectric dielectric layer is a thin film layer containing a material with piezoelectric properties, and the material is a perovskite composed of lead zirconate titanate.

[0009] It is further defined that both the internal positive electrode layer and the internal full negative electrode layer are produced by silver-palladium electrode slurry.

[0010] It is further defined that the outer structure of the internal positive electrode layer is a rounded rectangular film with six faces, the face where the external positive electrode layer is located is exposed, and the other three faces and the upper and lower faces are wrapped by the piezoelectric dielectric layer.

[0011] It is further defined that the outer structure of the internal all-negative electrode layer is a rectangular film with a total of six faces, the face where the external negative electrode layer is located and the two adjacent faces are exposed, and the upper and lower faces and the face where the external positive electrode layer is located are wrapped by a piezoelectric dielectric layer.

[0012] The manufacturing process of the laminated piezoelectric ceramic full electrode structure is characterized by comprising the following steps:

[0013] S1: heat-press multiple layers of piezoelectric dielectric films according to the designed thickness, and heat-press 10 layers of 45-micron-thick piezoelectric dielectric films at a temperature of 70 degrees and a pressure of 80 kg to form a lower insulating layer;

[0014] S2: Print the internal positive electrode layer on the lower insulating layer pressed in S1 and dry it at 80 degrees. After drying, stack the dielectric film on the internal positive electrode layer and perform hot pressing. After hot pressing, print the internal full negative electrode layer on the piezoelectric dielectric film and dry it again. Repeat the process described above to stack the internal positive electrode layer, the piezoelectric dielectric layer and the internal full negative electrode layer repeatedly until they are stacked to a specified height according to design requirements, and stack the upper insulating layer on the top.

[0015] S3: After the stacking in S2 is completed, the stacked piezoelectric ceramic is sealed and pressed at a temperature of 80 degrees, a pressure of 80 MPa, and a pressing time of 10 minutes;

[0016] S4: Cut the laminated piezoelectric ceramics after the pressure equalization in S3, with the cutting knife temperature of 80 degrees and the pressure of 10kg;

[0017] S5: After the cutting is completed in S4, debinding is performed, and the debinding temperature ranges from 0 to 550 degrees; the debinding time is 3 days;

[0018] S6: After the binder removal is completed in S5, sintering is performed at a sintering temperature of 1030 degrees and a sintering time of 1 day;

[0019] S7: grinding the multilayer piezoelectric ceramic sintered in S6, wherein the parallelism of the upper and lower surfaces is less than 5 microns, and the size tolerance is less than 5 microns; the parallelism of the side surfaces is less than 50 microns, and the size difference is less than 50 microns;

[0020] S8: After the outer dimensions of the multilayer piezoelectric ceramic are processed in S7, an external positive electrode layer and an external negative electrode layer are prepared, and then electrodes are screen-printed on the exposed sides of the internal positive electrode layer and the internal full negative electrode layer. After printing, the external positive electrode layer and the external negative electrode layer are sintered at a sintering temperature of 850 degrees for 12 hours.

[0021] S9: After the external positive electrode layer and the external negative electrode layer are sintered in S8, the multilayer piezoelectric ceramic is polarized at a polarization voltage of 300 V for 1 day, thereby completing the manufacturing.

[0022] The beneficial effects of the present invention are as follows: the present invention changes the electrode structure so that the stiffness of the non-electrode side of the electrode structure is separated, thereby greatly reducing the stress concentration on the side of the laminated piezoelectric ceramic. The piezoelectric ceramic will continue to deform during long-term operation, and the stress concentration point will be fatigued and damaged after 100 million times of use. After improvement, the use time can be extended to more than 500 million times. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0024] Figure 1 This is a schematic diagram of the external structure of the multi-layer piezoelectric ceramic full-electrode structure according to an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the internal structure of a multi-layer piezoelectric ceramic full-electrode structure according to an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the internal explosion structure of the multi-layer piezoelectric ceramic full-electrode structure according to an embodiment of the present invention;

[0027] The main component symbols are described as follows:

[0028] Upper insulating layer 1 , external positive electrode layer 2 , external negative electrode layer 3 , lower insulating layer 4 , piezoelectric dielectric layer 5 , internal positive electrode layer 6 , internal full negative electrode layer 7 . DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0030] like Figure 1-3As shown, the stacked piezoelectric ceramic full electrode structure of the present invention includes an upper insulating layer 1, an external positive electrode layer 2, an external negative electrode layer 3, a lower insulating layer 4, a piezoelectric dielectric layer 5, an internal positive electrode layer 6 and an internal full negative electrode layer 7. The upper insulating layer 1 and the lower insulating layer 4 are respectively arranged on the upper and lower end surfaces, the external positive electrode layer 2 and the external negative electrode layer 3 are arranged on two side surfaces opposite to each other, the external positive electrode layer 2 is connected to the internal positive electrode layer 6, the external negative electrode layer 3 is connected to the internal full negative electrode layer 7, the internal positive electrode layer 6 and the internal full negative electrode layer 7 are staggered, and the piezoelectric dielectric layer 5 is arranged between the internal positive electrode layer 6 and the internal full negative electrode layer 7.

[0031] Preferably, the external positive electrode layer 2 and the external negative electrode layer 3 are screen-printed silver pastes, which are sintered to form electrodes.

[0032] Preferably, the piezoelectric dielectric layer 5 is a thin film layer containing a material with piezoelectric properties, and the material is a perovskite composed of lead zirconate titanate.

[0033] Preferably, both the internal positive electrode layer 6 and the internal full negative electrode layer 7 are produced from silver-palladium electrode slurry.

[0034] Preferably, the outer structure of the internal positive electrode layer 6 is a rounded rectangular film with six faces, the face where the external positive electrode layer 2 is located is exposed, and the other three faces and the upper and lower faces are wrapped by the piezoelectric dielectric layer 5 .

[0035] Preferably, the internal full negative electrode layer 7 has a rectangular film structure with six faces, the face where the external negative electrode layer 3 is located and two adjacent faces are exposed, and the upper and lower faces and the face where the external positive electrode layer 2 is located are wrapped by the piezoelectric dielectric layer 5.

[0036] The manufacturing process of the laminated piezoelectric ceramic full electrode structure is characterized by comprising the following steps:

[0037] S1: heat-pressing a plurality of piezoelectric dielectric films according to a designed thickness, and heat-pressing 10 piezoelectric dielectric films with a thickness of 45 microns at a temperature of 70 degrees and a pressure of 80 kg to form a lower insulating layer 4;

[0038] S2: Print the internal positive electrode layer 6 on the lower insulating layer 4 pressed in S1 and dry it at a temperature of 80 degrees. After drying, stack a dielectric film on the internal positive electrode layer 6 and perform hot pressing. After hot pressing, print the internal full negative electrode layer 7 on the piezoelectric dielectric film and dry it again. In the process described above, stack the internal positive electrode layer 6, the piezoelectric dielectric layer 5 and the internal full negative electrode layer 7 repeatedly until they are stacked to a specified height according to design requirements, and stack the upper insulating layer 1 on the top.

[0039] S3: After the stacking in S2 is completed, the stacked piezoelectric ceramic is sealed and pressed at a temperature of 80 degrees, a pressure of 80 MPa, and a pressing time of 10 minutes;

[0040] S4: Cut the laminated piezoelectric ceramics after the pressure equalization in S3, with the cutting knife temperature of 80 degrees and the pressure of 10kg;

[0041] S5: After the cutting is completed in S4, debinding is performed, and the debinding temperature ranges from 0 to 550 degrees; the debinding time is 3 days;

[0042] S6: After the binder removal is completed in S5, sintering is performed at a sintering temperature of 1030 degrees and a sintering time of 1 day;

[0043] S7: grinding the multilayer piezoelectric ceramic sintered in S6, wherein the parallelism of the upper and lower surfaces is less than 5 microns, and the size tolerance is less than 5 microns; the parallelism of the side surfaces is less than 50 microns, and the size difference is less than 50 microns;

[0044] S8: After the outer dimensions of the multilayer piezoelectric ceramic are processed in S7, an external positive electrode layer 2 and an external negative electrode layer 3 are prepared, and then the electrodes are screen-printed on the exposed sides of the internal positive electrode layer 6 and the internal full negative electrode layer 7, respectively. After the printing is completed, the external positive electrode layer 2 and the external negative electrode layer 3 are sintered at a sintering temperature of 850 degrees and a sintering time of 12 hours;

[0045] S9: After the sintering of the external positive electrode layer 2 and the external negative electrode layer 3 is completed in S8, the multilayer piezoelectric ceramic is polarized at a polarization voltage of 300 V for 1 day, thereby completing the manufacturing.

[0046] In this embodiment, an internal positive electrode layer 6 of silver-palladium material is printed on the surface of the lower insulating layer 4, and a piezoelectric dielectric layer 5 with a thickness of microns is placed. After hot pressing and bonding, an internal full negative electrode layer 7 of silver-palladium material is printed on the upper surface of the pressed piezoelectric dielectric layer 5. The layers are stacked in sequence to 90 layers or more in the order described above, and an upper insulating layer 1 is stacked on the top, and warm isostatic pressing is performed. After pressing, it is cut into squares and placed in a high-temperature furnace for sintering at a certain gradient. After sintering, an external positive electrode layer 2 and an external negative electrode layer 3 of silver material are printed on the electrode ends on both sides. After the piezoelectric ceramic is polarized, a voltage is applied to the external positive electrode layer 2. The piezoelectric dielectric layer 5 is acted upon by an electric field, and the piezoelectric ceramic generates internal electric domain movement, and the piezoelectric ceramic outputs displacement. The applied voltage and the displacement output by the stacked piezoelectric ceramic are nearly linearly related, thereby realizing micro-nano motion control.

[0047] Among them, the upper insulating layer and the lower insulating layer are made of an integral sintered structure. The upper insulating layer 1 and the lower insulating layer 4 serve as the mounting and fixing surfaces of the external device, and can isolate the internal electrode from the conductivity of the device at the mounting position. The external positive electrode layer 2 is connected to each group of internal positive electrode layers 6 in the internal structure, and the external negative electrode layer 3 is connected to each group of internal full negative electrode layers 7 in the internal structure, forming an interdigitated structure of positive and negative electrode layers. After a uniformly distributed electric field is applied to the upper and lower surfaces of the piezoelectric dielectric layer 5, the piezoelectric dielectric layer produces a piezoelectric effect, and produces different deformations according to the magnitude of the voltage. The internal positive electrode layer 6 is the internal positive electrode layer of the laminated piezoelectric ceramic. The positive electrode pattern is printed on the piezoelectric dielectric layer with a screen printing plate, and the positive electrode is evenly distributed on the piezoelectric dielectric layer. The internal full negative electrode layer 7 is the internal negative electrode layer of the laminated piezoelectric ceramic. The negative electrode pattern is printed on the piezoelectric dielectric layer with a screen printing plate, and the negative electrode is evenly distributed on the piezoelectric dielectric layer.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. Multilayer piezoelectric ceramic full electrode structure, characterized by: The invention comprises an upper insulating layer (1), an external positive electrode layer (2), an external negative electrode layer (3), a lower insulating layer (4), a piezoelectric dielectric layer (5), an internal positive electrode layer (6) and an internal full negative electrode layer (7), wherein the upper insulating layer (1) and the lower insulating layer (4) are respectively arranged on the upper and lower end surfaces, the external positive electrode layer (2) and the external negative electrode layer (3) are arranged on two side surfaces opposite to each other, the external positive electrode layer (2) is connected to the internal positive electrode layer (6), the external negative electrode layer (3) is connected to the internal full negative electrode layer (7), the internal positive electrode layer (6) and the internal full negative electrode layer (7) are arranged in an interlaced manner, and the piezoelectric dielectric layer (5) is arranged between the internal positive electrode layer (6) and the internal full negative electrode layer (7); The external positive electrode layer (2) and the external negative electrode layer (3) are screen-printed silver pastes, which are sintered to form electrodes; The internal positive electrode layer (6) has a rounded rectangular film structure with six faces, the face where the external positive electrode layer (2) is located is exposed, and the other three faces and the upper and lower faces are wrapped by the piezoelectric dielectric layer (5); The stacked piezoelectric ceramic full-electrode structure is manufactured by the following process, including the following steps: S1: hot pressing a plurality of piezoelectric dielectric films according to a designed thickness, wherein 10 piezoelectric dielectric films with a thickness of 45 microns are stacked and hot pressing is performed at a temperature of 70 degrees and a pressure of 80 kg to form a lower insulating layer (4); S2: Print the internal positive electrode layer (6) on the lower insulating layer (4) pressed in S1 and dry it at a temperature of 80 degrees. After drying, stack a dielectric film on the internal positive electrode layer (6) and perform heat pressing. After heat pressing, print the internal full negative electrode layer (7) on the piezoelectric dielectric film and dry it again. Repeat the process described above to stack the internal positive electrode layer (6), the piezoelectric dielectric layer (5) and the internal full negative electrode layer (7) to a specified height according to design requirements, and stack the upper insulating layer (1) on the top. S3: After the stacking in S2 is completed, the stacked piezoelectric ceramic is sealed and pressed at a temperature of 80 degrees, a pressure of 80 MPa, and a pressing time of 10 minutes; S4: Cut the laminated piezoelectric ceramics after the pressure equalization in S3, with the cutting knife temperature of 80 degrees and the pressure of 10kg; S5: After the cutting is completed in S4, debinding is performed, and the debinding temperature ranges from 0 to 550 degrees; the debinding time is 3 days; S6: After the binder removal is completed in S5, sintering is performed at a sintering temperature of 1030 degrees and a sintering time of 1 day; S7: grinding the multilayer piezoelectric ceramic sintered in S6, wherein the parallelism of the upper and lower surfaces is less than 5 microns, and the size tolerance is less than 5 microns; the parallelism of the side surfaces is less than 50 microns, and the size difference is less than 50 microns; S8: After the outer dimensions of the multilayer piezoelectric ceramic are processed in S7, an external positive electrode layer (2) and an external negative electrode layer (3) are prepared, and then electrodes are screen-printed on the exposed sides of the internal positive electrode layer (6) and the internal full negative electrode layer (7). After printing, the external positive electrode layer (2) and the external negative electrode layer (3) are sintered at a sintering temperature of 850 degrees and a sintering time of 12 hours; S9: After the sintering of the external positive electrode layer (2) and the external negative electrode layer (3) is completed in S8, the multilayer piezoelectric ceramic is polarized at a polarization voltage of 300 V for 1 day, thereby completing the manufacturing.

2. The multi-layer piezoelectric ceramic full-electrode structure according to claim 1, characterized in that: The piezoelectric dielectric layer (5) is a thin film layer containing a material with piezoelectric properties, and the material is a perovskite composed of lead zirconate titanate.

3. The multi-layer piezoelectric ceramic full-electrode structure according to claim 2, characterized in that: The internal positive electrode layer (6) and the internal full negative electrode layer (7) are both produced from silver-palladium electrode slurry.

4. The multi-layer piezoelectric ceramic full-electrode structure according to claim 1, characterized in that: The internal full negative electrode layer (7) has a rectangular thin film structure with six faces, the face where the external negative electrode layer (3) is located and two adjacent faces are exposed, and the upper and lower faces and the face where the external positive electrode layer (2) is located are wrapped by the piezoelectric dielectric layer (5).

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