Multilayer piezoelectric ceramic driver and preparation method thereof

Abstract

The invention relates to a multilayer piezoelectric ceramic driver and a preparation method thereof, and belongs to the technical field of piezoelectric ceramic drivers. The driver comprises piezoelectric ceramics, inner electrodes, outer electrodes and insulating layers A. The piezoelectric ceramics and the inner electrodes are alternately stacked to form a ceramic green body, the inner electrodes are alternately covered on the two opposite sides of the ceramic green body through the insulating layers A, only one side of the inner electrode of each layer is exposed, the outer electrodes are arranged on the side wall, where the insulating layers A are located, of the ceramic green body, and the outer electrodes are arranged on the side wall of the ceramic green body. And the outer electrode is in contact with the exposed side of the inner electrode. All the inner electrodes are arranged between the piezoelectric ceramics, namely, the inner electrodes are all electrodes, the utilization rate of the electrodes is improved (100%), all the piezoelectric ceramics are covered with the inner electrodes, interlayer thickness difference does not exist, the crack generation risk is reduced, the yield of the co-firing process is improved, meanwhile, the inner electrodes do not have inactive areas, stress concentration or crack propagation does not exist, and the dynamic service life is prolonged.

Description

Technical Field

[0001] The present invention relates to a multilayer piezoelectric ceramic driver and a preparation method thereof, belonging to the technical field of piezoelectric ceramic drivers. Background Art

[0002] Piezoelectric ceramics, as functional materials that enable the conversion of mechanical and electrical energy, play an important role in numerous fields. Multilayer piezoelectric ceramic stacks consist of multiple piezoelectric ceramic sheets connected alternately by electrodes. When an electric field is applied, the piezoelectric ceramic sheets deform. Due to the stacking of these multiple layers, the overall displacement is significantly increased. With the advancement of industrial intelligence, the demand for high-precision, high-efficiency, and high-reliability actuators is growing, giving rise to the need for multilayer piezoelectric ceramic actuators.

[0003] Currently, most multilayer piezoelectric ceramic actuators on the market use a localized internal electrode stack structure. For example, the partitioned structure of the multilayer piezoelectric ceramic actuator disclosed in Chinese patent document CN118157512A has achieved certain displacement output and response speed, but still has the following disadvantages: 1. Low electrode utilization: The traditional laminated structure adopts a local internal electrode design, and only part of the area participates in the electric field, resulting in insufficient effective strain area (usually <60%) and limited displacement output (single layer strain <0.1%). 2. Process defects: Micro cracks between layers are easily generated during the co-firing process (defect rate > 3%); 3. Reduced life: There is an inactive area at the edge of the inner electrode, which generates interlayer stress concentration during operation (the peak value of interlayer shear stress reaches 80-120MPa). Under cyclic load, the interface crack expands, resulting in a reduced life. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a multilayer piezoelectric ceramic driver and a method for preparing the same.

[0005] The technical solutions of the present invention are as follows: A multilayer piezoelectric ceramic driver includes piezoelectric ceramics, inner electrodes, outer electrodes, and an insulating layer A. The piezoelectric ceramics and the inner electrodes are alternately stacked to form a ceramic green body. The inner electrodes are alternately covered with the insulating layer A on opposite sides of the ceramic green body, so that only one side of the inner electrode of each layer is exposed to the outside. The outer electrode is provided on the side wall of the ceramic green body where the insulating layer A is located, and the outer electrode contacts the side where the inner electrode is exposed to the outside.

[0006] Preferably, according to the present invention, the cross-sectional shape of the piezoelectric ceramic and the inner electrode is the same, so that the inner electrode can be placed entirely between the piezoelectric ceramics, that is, the inner electrode is a full electrode, thereby improving the electrode utilization rate (100%), and the inner electrode completely covers the piezoelectric ceramic, without any difference in thickness between layers, thereby reducing the risk of cracks and improving the yield of the co-firing process. At the same time, the inner electrode has no inactive area, no stress concentration or crack extension, thereby improving the dynamic working life.

[0007] Preferably, according to the present invention, the piezoelectric ceramic and the inner electrode are both rectangular parallelepipeds, and insulating layers B are provided on the other two sides of the ceramic green body. The four-side insulating layer design realizes comprehensive protection to prevent moisture intrusion and electrode migration.

[0008] According to a preferred embodiment of the present invention, the insulating layer A and the insulating layer B are made of PZT-based materials with a thickness of 10-50 μm.

[0009] According to the preferred embodiment of the present invention, the piezoelectric ceramic has a thickness of 10-130 μm.

[0010] According to the preferred embodiment of the present invention, the inner electrode material is palladium silver, and the palladium content is 0-30%; The outer electrode material is silver.

[0011] The preparation method of the multilayer piezoelectric ceramic driver comprises the following steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramics; (2) Printing inner electrodes on the ceramic film tape to form a ceramic film tape with inner electrodes; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Polish or plasma clean the sides of the ceramic green body to remove surface impurities, and then print the insulating layer A on both sides. The insulating layer A covers the odd-numbered internal electrodes on one side, and the other side covers the even-numbered internal electrodes on the opposite side. The remaining two sides are coated with the insulating layer B. (5) Printing a conductive layer on the side of the ceramic green body where the insulating layer A is located to form two sets of alternatingly conductive external electrodes; (6) Sintering at a low temperature of 800-950°C to combine the insulating layer A, insulating layer B, external electrode and ceramic sintered body.

[0012] (7) The two outer electrodes are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

[0013] The preparation method of the multilayer piezoelectric ceramic driver comprises the following steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramics; (2) Printing inner electrodes on the ceramic film tape to form a ceramic film tape with inner electrodes; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Coating the insulating layer A and the insulating layer B on the four sides of the ceramic green body respectively; (5) Using a laser to remove part of the insulating layer A to expose the inner electrode, a conductive layer is then printed on the side of the ceramic green body where the insulating layer A is located to form two sets of alternatingly conductive outer electrodes; (6) Sintering at a low temperature of 800-950°C to combine the insulating layer A, insulating layer B, external electrode and ceramic sintered body.

[0014] (7) The two outer electrodes are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

[0015] According to the present invention, further preferably, in step (5), a 1064 nm laser is used to remove part of the insulating layer A with a line width of 10-50 μm, the laser power is 20-50 W, and the scanning speed is 0.5-2 m / s.

[0016] The beneficial effects of the present invention are: 1. The inner electrodes of the present invention are all placed between the piezoelectric ceramics, that is, the inner electrodes are full electrodes, which improves the electrode utilization rate (100%). Moreover, the inner electrodes completely cover the piezoelectric ceramics without any thickness difference between the layers, reducing the risk of cracks and improving the yield of the co-firing process. At the same time, the inner electrodes have no inactive areas, no stress concentration or crack expansion, and improve the dynamic working life.

[0017] 2. The present invention uses a secondary sintering process during preparation. The second sintering temperature is lower than the sintering temperature of the ceramic body, which reduces process complexity and makes the insulating layer A and the insulating layer B closely bonded to the sintered body, reducing interface stress.

[0018] 3. During the preparation of the present invention, a laser processing technology is introduced, and the laser processing accuracy reaches the micron level, which reduces the alignment error between the insulating layer and the external electrode, avoids the defects of the traditional mask process, and reduces the risk of short circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Fig. 1 This is a schematic side cross-sectional view of the insulating layer A of the present invention; Fig. 2 This is a side cross-sectional schematic diagram of the insulating layer B of the present invention; Fig. 3 Schematic diagram of the preparation process of Example 1 of the present invention.

[0020] Wherein: 1. piezoelectric ceramic; 2. inner electrode; 3. outer electrode; 4. insulating layer A; 5. insulating layer B. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto.

[0022] Example 1: like Figs. 1-3 As shown, this embodiment provides a multilayer piezoelectric ceramic driver, including a piezoelectric ceramic 1, an inner electrode 2, an outer electrode 3 and an insulating layer A4, wherein the piezoelectric ceramic 1 and the inner electrode 2 are alternately stacked to form a ceramic green body, and the inner electrodes are alternately covered with the insulating layer A4 on opposite sides of the ceramic green body, so that only one side of the inner electrode 2 of each layer is exposed to the outside, and the outer electrode 3 is provided on the side wall of the ceramic green body where the insulating layer A4 is located, and the outer electrode 3 contacts the side where the inner electrode 2 is exposed to the outside.

[0023] The piezoelectric ceramic 1 and the inner electrode 2 have the same cross-sectional shape, so that the inner electrode can be placed entirely between the piezoelectric ceramics, that is, the inner electrode is a full electrode, which improves the electrode utilization rate (100%). Moreover, the inner electrode completely covers the piezoelectric ceramic, with no thickness difference between layers, reducing the risk of cracks and improving the yield of the co-firing process. At the same time, the inner electrode has no inactive area, no stress concentration or crack expansion, and improves the dynamic working life.

[0024] The piezoelectric ceramic 1 and the inner electrode 2 are both rectangular parallelepipeds, and an insulating layer B5 is provided on the other two sides of the ceramic green body. The four-sided insulating layer design provides comprehensive protection to prevent moisture intrusion and electrode migration.

[0025] The insulating layer A4 and the insulating layer B5 are made of PZT-based materials with a thickness of 10-50 μm.

[0026] The piezoelectric ceramic 1 has a thickness of 10 to 130 μm.

[0027] The inner electrode 2 is made of palladium silver with a palladium content of 0-30%. The outer electrode 3 is made of silver.

[0028] The difference in thermal expansion coefficient between the insulating layer A4 and the insulating layer B5 and the piezoelectric ceramic 1 is less than 5%, and the porosity of the insulating layer A4 and the insulating layer B5 is less than 5%.

[0029] Example 2: A method for preparing the multilayer piezoelectric ceramic driver according to Example 1 comprises the following steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramic 1; (2) Printing an inner electrode 2 on the ceramic film tape to form a ceramic film tape with an inner electrode; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Polish or plasma clean the sides of the ceramic green body to remove surface impurities, and then print the insulating layer A4 on both sides. The insulating layer A4 covers the odd-numbered internal electrodes on one side, and the other side covers the even-numbered internal electrodes on the opposite side. The remaining two sides are coated with the insulating layer B5; (5) Printing a conductive layer on the side of the ceramic green body where the insulating layer A4 is located to form two groups of alternatingly conductive external electrodes 3; (6) Low-temperature sintering at 800-950°C is performed to combine the insulating layer A4, the insulating layer B5, the external electrode 3 and the ceramic sintered body.

[0030] (7) The two outer electrodes 3 are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

[0031] Example 3: A method for preparing the multilayer piezoelectric ceramic driver according to Example 1 comprises the following steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramic 1; (2) Printing an inner electrode 2 on the ceramic film tape to form a ceramic film tape with an inner electrode; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Coating the insulating layer A4 and the insulating layer B5 on the four sides of the ceramic green body respectively; (5) A 1064 nm laser is used to remove part of the insulating layer A4 with a line width of 10-50 μm. The laser power is 20-50 W and the scanning speed is 0.5-2 m / s to expose the inner electrode 2. Then, a conductive layer is printed on the side of the ceramic green body where the insulating layer A4 is located to form two sets of alternatingly conductive outer electrodes 3. (6) Low-temperature sintering at 800-950°C is performed to combine the insulating layer A4, the insulating layer B5, the external electrode 3 and the ceramic sintered body.

[0032] (7) The two outer electrodes 3 are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

Claims

1. A multilayer piezoelectric ceramic driver, characterized in that: It includes piezoelectric ceramics, inner electrodes, outer electrodes and insulating layer A, wherein the piezoelectric ceramics and the inner electrodes are alternately stacked to form a ceramic green body, and the inner electrodes are alternately covered with insulating layer A on opposite sides of the ceramic green body, so that only one side of the inner electrode of each layer is exposed to the outside, and an outer electrode is provided on the side wall of the ceramic green body where the insulating layer A is located, and the outer electrode contacts the side where the inner electrode is exposed to the outside.

2. The multilayer piezoelectric ceramic driver according to claim 1, wherein The cross-sectional shapes of the piezoelectric ceramic and the inner electrode are the same.

3. The multilayer piezoelectric ceramic driver according to claim 2, wherein: The piezoelectric ceramic and the inner electrode are both rectangular parallelepipeds, and insulating layers B are provided on the other two sides of the ceramic green body.

4. The multilayer piezoelectric ceramic driver according to claim 3, wherein: The insulating layer A and the insulating layer B are made of PZT-based materials with a thickness of 10-50 μm.

5. The multilayer piezoelectric ceramic driver according to claim 3, wherein: The thickness of piezoelectric ceramics is 10~130um.

6. The multilayer piezoelectric ceramic driver according to claim 3, wherein: The inner electrode material is palladium silver with a palladium content of 0~30%, and the outer electrode material is silver.

7. The method for preparing a multilayer piezoelectric ceramic actuator according to claim 3, wherein: Here are the steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramics; (2) Printing inner electrodes on the ceramic film tape to form a ceramic film tape with inner electrodes; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Polish or plasma clean the sides of the ceramic green body to remove surface impurities, and then print the insulating layer A on both sides. The insulating layer A covers the odd-numbered internal electrodes on one side, and the other side covers the even-numbered internal electrodes on the opposite side. The remaining two sides are coated with the insulating layer B. (5) Printing a conductive layer on the side of the ceramic green body where the insulating layer A is located to form two sets of alternatingly conductive external electrodes; (6) Sintering at a low temperature of 800-950°C to combine the insulating layer A, the insulating layer B, the external electrode and the ceramic sintered body; (7) The two outer electrodes are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

8. The method for preparing a multilayer piezoelectric ceramic driver according to claim 3, wherein: Here are the steps: (1) Tape-cast ceramic film strip, i.e. piezoelectric ceramics; (2) Printing inner electrodes on the ceramic film tape to form a ceramic film tape with inner electrodes; (3) Stacking the ceramic membrane strips with inner electrodes, with the number of layers >2, to form a ceramic green body, which is then sintered at 900-1150 °C to form a dense ceramic sintered body; (4) Coating the insulating layer A and the insulating layer B on the four sides of the ceramic green body respectively; (5) Using a laser to remove part of the insulating layer A to expose the inner electrode, a conductive layer is then printed on the side of the ceramic green body where the insulating layer A is located to form two sets of alternatingly conductive outer electrodes; (6) Sintering at a low temperature of 800-950°C to combine the insulating layer A, the insulating layer B, the external electrode and the ceramic sintered body; (7) The two outer electrodes are electrically polarized to obtain a full-electrode multilayer piezoelectric ceramic actuator.

9. The method for preparing a multilayer piezoelectric ceramic driver according to claim 8, wherein: In step (5), a 1064 nm laser is used to remove part of the insulating layer A with a line width of 10-50 μm, the laser power is 20-50 W, and the scanning speed is 0.5-2 m / s.

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