Piezoelectric actuator and manufacturing method thereof

Abstract

The invention provides a piezoelectric driver. The piezoelectric driver comprises a plurality of piezoelectric driving stacks which are stacked in sequence, and the driving expansion and contraction amount of the piezoelectric driver is equal to the sum of the driving expansion and contraction amounts of the piezoelectric driving stacks. The piezoelectric driving stack comprises a plurality of piezoelectric driving chips which are stacked in sequence, each piezoelectric driving chip comprises a ceramic insulating layer and an electrode, the ceramic insulating layers and the electrodes are alternately arranged in sequence, and each ceramic insulating layer is provided with a first through hole, namely a center hole of the ceramic insulating layer; the electrode comprises a pole piece part and a pin part, the pole piece part is provided with a second through hole which is coaxial with the first through hole and has a diameter larger than that of the first through hole, the diameter of the second through hole is larger than that of the first through hole, and a ceramic insulating ring playing an insulating role is formed between the edge of the electrode and the edge of the center hole; the projection of the pole piece part in the thickness direction is within the outer contour projection of the ceramic insulating layer, absolute insulation between the pole piece part and an adjacent layer electrode is ensured, and in order to ensure electric connection of the same-polarity electrode, the pin part needs to extend to the outer contour edge of the ceramic insulating layer.

Description

Technical Field

[0001] The present application belongs to the technical field of piezoelectric actuators, and more specifically, to a piezoelectric actuator and a method for manufacturing the same. Background Art

[0002] In the context of the rapid development of modern science and technology, the importance of piezoelectric actuators, as a precision component integrating micro-drive and micro-control functions, has become increasingly prominent, especially in many cutting-edge fields such as mechanical manufacturing, optical instruments, and communication technology. These fields place extremely high demands on the accuracy, response speed, and environmental adaptability of the actuator. Among them, the piezoelectric actuator with a through hole in the center is particularly important in specific application scenarios such as optical fiber stretching systems and precision mechanical matching devices due to its unique design.

[0003] Optical fiber communication technology is the cornerstone of modern information transmission. Precise control of optical fiber length is the key to achieving optical pulse delay and optimizing signal transmission quality. The central through-hole piezoelectric driver was born based on this demand. Its design cleverly introduces a through-hole structure in the center of the driver, which not only facilitates the insertion and fixation of the optical fiber, but also directly acts on the optical fiber through the tensile strain generated by the piezoelectric effect, achieving fine adjustment of the optical fiber length, thereby controlling the transmission time of the optical pulse and improving the overall performance of the communication system.

[0004] However, in the manufacturing process of the center through-hole piezoelectric actuator, how to effectively achieve the insulation treatment of the center through-hole while ensuring the wear resistance and long-term stability of the structure has become a technical problem that needs to be solved urgently. Traditional manufacturing methods mostly use organic coatings on the inner wall of the center through-hole to achieve insulation. Although this method can meet the insulation requirements to a certain extent, it has defects such as complex process, easy wear of the coating, and poor long-term stability. Organic coatings are easily affected by environmental factors such as temperature, humidity changes, and mechanical friction during long-term use, which leads to a decrease in insulation performance and may even cause safety hazards such as short circuits, which seriously restricts the promotion and application of center through-hole piezoelectric actuators in high-end application fields. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a piezoelectric driver and a method for manufacturing the same, so as to solve the technical problem of unstable performance of the insulating layer at the central through hole of the piezoelectric driver existing in the prior art.

[0006] To achieve the above purpose, the technical solution adopted in this application is:

[0007] A piezoelectric actuator is provided, comprising:

[0008] A plurality of sequentially stacked piezoelectric drive stacks, wherein the piezoelectric drive stacks include a plurality of sequentially stacked piezoelectric drive chips, wherein the piezoelectric drive chips include ceramic insulating layers and electrodes, wherein the ceramic insulating layers and the electrodes are alternately arranged in sequence;

[0009] The ceramic insulating layer is provided with a first through hole; the electrode includes a pole piece portion and a pin portion, the pole piece portion is provided with a second through hole which is coaxially arranged with the first through hole and has a diameter larger than the first through hole; the projection of the pole piece portion along the thickness direction is within the projection of the outer contour of the ceramic insulating layer, and the pin portion extends to the edge of the outer contour of the ceramic insulating layer.

[0010] As a further improvement of the above technical solution:

[0011] Optionally, the electrode includes a positive electrode and a negative electrode, the positive electrode and the negative electrode are arranged alternately in sequence, the ceramic insulating layer is arranged between the positive electrode and the negative electrode, the pin portion of the positive electrode faces one side on the plane of the piezoelectric driving chip, and the pin portion of the negative electrode faces the other side on the plane of the piezoelectric driving chip.

[0012] Optionally, the piezoelectric drive stack further includes end surface conductive layers arranged in pairs, wherein the end surface conductive layers arranged in pairs are respectively arranged on both sides of the piezoelectric drive stack, one of the end surface conductive layers arranged in pairs is electrically connected to the positive electrode; and the other of the end surface conductive layers arranged in pairs is electrically connected to the negative electrode.

[0013] Optionally, the minimum distance from the first through hole to the second through hole is greater than 0.01 mm.

[0014] Optionally, the aperture of the first through hole ranges from 1 mm to 20 mm.

[0015] The present application also provides a method for manufacturing a piezoelectric actuator, comprising the following steps:

[0016] Preparation of green porcelain tape: Piezoelectric ceramic powder is slurried, and then tape-casted to obtain a green porcelain tape of a certain thickness, and holes are punched on the green porcelain tape;

[0017] Printing electrodes: Printing electrode patterns on green porcelain tape;

[0018] Preparation of green blocks: After the green porcelain tapes are stacked one by one to a certain thickness, they are pressed into green blocks by isostatic pressing;

[0019] Cutting the green block: cutting the green block into individual green blocks;

[0020] Opening a center hole: opening a center hole on each individual green body;

[0021] Debinding and sintering: Each green body is placed in a debinding furnace for heating to remove the colloid in the green body; then transferred to a sintering furnace to sinter into a piezoelectric drive chip;

[0022] Grinding: Grind the piezoelectric driver chip to the specified shape and size;

[0023] Bonding alignment: bonding the piezoelectric drive chips one by one into a piezoelectric drive stack;

[0024] Plating an end surface conductive layer: Plating an end surface conductive layer on both ends of the piezoelectric drive stack;

[0025] Welding leads: Weld the positive and negative leads on the end surface conductive layer;

[0026] Polarization treatment: polarize the piezoelectric drive stack with welded leads.

[0027] As a further improvement of the above technical solution:

[0028] Optionally, the step of opening a center hole on each individual green body may be arranged after the step of cutting the green body block, or after the debinding and sintering step, or after the bonding and alignment step.

[0029] Optionally, when printing the electrodes, a printing screen is used to print the electrode pattern, wherein the printing screen has a plurality of electrode patterns arranged in a rectangular array, and also has positioning holes and cutting line holes surrounding the outside of the rectangular array.

[0030] Optionally, when preparing the green porcelain tape, the thickness of the green porcelain tape ranges from 20 μm to 80 μm.

[0031] Optionally, when preparing the green block, the number of layers of the green porcelain tape is in the range of 40 to 200 layers.

[0032] Compared with the prior art, the piezoelectric actuator and the manufacturing method thereof provided by the present application have the following beneficial effects:

[0033] The piezoelectric driver provided by the present application comprises a plurality of piezoelectric drive stacks stacked in sequence. The driving expansion and contraction amount of the piezoelectric driver is equal to the sum of the driving expansion and contraction amounts of each piezoelectric drive stack. The piezoelectric drive stack comprises a plurality of piezoelectric drive chips stacked in sequence, the piezoelectric drive chip being the smallest functional unit of the piezoelectric driver, and the sum of the driving expansion and contraction amounts of each piezoelectric drive chip being equal to the driving expansion and contraction amount of the piezoelectric drive stack. The piezoelectric drive chip specifically comprises a ceramic insulating layer and an electrode. The ceramic insulating layer and the electrode are alternately arranged in sequence to form a piezoelectric drive chip together. The ceramic insulating layer has a first through hole, i.e., a central hole of the ceramic insulating layer. The electrode comprises a pole piece and a pin portion. To ensure a better insulation effect at the central hole, the pole piece has a second through hole coaxially arranged with the first through hole and having a diameter greater than the first through hole; since the diameter of the second through hole is greater than the diameter of the first through hole, there is a section of a ceramic insulating ring between the edge of the electrode and the edge of the central hole that acts as an insulator, and the current cannot cross the ceramic insulating ring to conduct with the electrode of the adjacent layer, so there will be no short circuit and other problems. This section of ceramic insulating ring replaces the organic insulating layer at the center hole of the traditional piezoelectric driver. The performance of the ceramic insulating ring is more stable than that of the organic insulating layer. Environmental factors such as temperature and humidity have less impact on the ceramic insulating ring. Moreover, the ceramic insulating ring is smoother and more wear-resistant than the organic insulating layer, and no longer requires a complex coating process. In addition, the projection of the pole piece along the thickness direction is within the projection of the outer contour of the ceramic insulating layer. Its purpose is also to ensure absolute insulation from the electrodes of the adjacent layers and prevent the pole piece from touching the outer contour edge of the ceramic insulating layer and causing a short circuit. However, in order to ensure the electrical connection of electrodes of the same polarity, the pin portion must also extend to the outer contour edge of the ceramic insulating layer so that the electrodes of the same polarity can be turned on. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A schematic diagram of a partial cross-sectional structure of a piezoelectric drive chip provided in this application;

[0036] Figure 2 A schematic diagram of the planar structure of the first electrode provided in this application;

[0037] Figure 3 A schematic diagram of the planar structure of the second electrode provided in this application;

[0038] Figure 4 A schematic diagram of the planar structure of the third electrode provided in this application;

[0039] Figure 5 A schematic diagram of the planar structure of the fourth electrode provided in this application;

[0040] Figure 6 A schematic diagram of the planar structure of the fifth electrode provided in this application;

[0041] Figure 7 A schematic diagram of the planar structure of the sixth electrode provided in this application;

[0042] Figure 8 A schematic diagram of the three-dimensional structure of the piezoelectric drive stack provided in this application;

[0043] Fig. 9 This is a schematic diagram of the planar structure of the printing screen provided in this application.

[0044] Among them, the reference numerals in the figure are:

[0045] 1. Piezoelectric drive stack; 11. Piezoelectric drive chip; 111. Ceramic insulation layer; 1111. First through hole; 112. Electrode; 1121. Pole piece; 1122. Pin; 1123. Second through hole; 12. End surface conductive layer. DETAILED DESCRIPTION

[0046] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0048] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] like Figure 1 and Figure 8 As shown, the present application provides a piezoelectric driver, which utilizes the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into mechanical energy or mechanical motion. The piezoelectric driver includes a plurality of piezoelectric drive stacks 1 stacked in sequence. The driving expansion and contraction amount of the piezoelectric driver is equal to the sum of the driving expansion and contraction amounts of each piezoelectric drive stack 1. The piezoelectric drive stack 1 includes a plurality of piezoelectric drive chips 11 stacked in sequence. The piezoelectric drive chip 11 serves as the smallest functional unit of the piezoelectric driver, and the sum of the driving expansion and contraction amounts of each piezoelectric drive chip 11 is equal to the driving expansion and contraction amount of the piezoelectric drive stack 1. The piezoelectric drive chip 11 specifically includes a ceramic insulating layer 111 and an electrode 112. The ceramic insulating layer 111 and the electrode 112 are alternately arranged in sequence, and together constitute the piezoelectric drive chip 11.

[0051] The ceramic insulating layer 111 has a first through hole 1111, that is, the center hole of the ceramic insulating layer 111. The electrode 112 includes a pole piece 1121 and a pin 1122. To ensure a better insulation effect at the center hole, the pole piece 1121 has a second through hole 1123 coaxially arranged with the first through hole 1111 and having a diameter greater than the first through hole 1111; since the diameter of the second through hole 1123 is greater than the diameter of the first through hole 1111, there is a section of ceramic insulating ring between the edge of the electrode 112 and the edge of the center hole that plays an insulating role, and the current cannot cross the ceramic insulating ring to conduct with the electrode 112 of the adjacent layer, so there will be no short circuit and other problems. This section of ceramic insulating ring replaces the organic insulating layer at the center hole of the traditional piezoelectric driver. The performance of the ceramic insulating ring is more stable than that of the organic insulating layer, and the environmental factors such as temperature and humidity have less impact on the ceramic insulating ring. In addition, the ceramic insulating ring is smoother and more wear-resistant than the organic insulating layer, and no longer requires a complex coating process.

[0052] In addition, if Figures 2 to 7 As shown, the projection of the pole piece 1121 in the thickness direction is within the projection of the outer contour of the ceramic insulating layer 111, and its purpose is also to ensure absolute insulation from the electrode 112 of the adjacent layer and prevent the pole piece 1121 from touching the outer contour edge of the ceramic insulating layer 111 and causing a short circuit. However, in order to ensure the electrical connection of the electrodes 112 of the same polarity, the pin portion 1122 needs to extend to the outer contour edge of the ceramic insulating layer 111 so as to conduct the electrodes 112 of the same polarity.

[0053] like Figure 1 and Figure 8 As shown, in one embodiment of the present application, the electrode 112 includes a positive electrode and a negative electrode, and the positive electrode and the negative electrode are arranged alternately in sequence. The ceramic insulating layer 111 is arranged between the positive electrode and the negative electrode to play an insulating role. At the same time, the ceramic insulating layer 111 generates an inverse piezoelectric effect under the action of the electric field formed by the positive / negative electrodes. To avoid a short circuit between the positive electrode and the negative electrode, the pin portion 1122 of the positive electrode faces one side of the plane of the piezoelectric drive chip 11, and the pin portion 1122 of the negative electrode faces the other side of the plane of the piezoelectric drive chip 11, so that the positive electrode and the negative electrode maintain a safe spacing distance to avoid the occurrence of a short circuit.

[0054] like Figure 1 and Figure 8 As shown, in one embodiment of the present application, the piezoelectric drive stack 1 further includes end surface conductive layers 12 arranged in pairs, and the end surface conductive layers 12 are used to conduct each of the same polarity electrodes 112. Specifically, the end surface conductive layers 12 arranged in pairs are respectively arranged on both sides of the piezoelectric drive stack 1, one of the end surface conductive layers 12 arranged in pairs is electrically connected to the positive electrode; and the other of the end surface conductive layers 12 arranged in pairs is electrically connected to the negative electrode.

[0055] In one embodiment of the present application, the minimum distance from the first through hole 1111 to the second through hole 1123 is greater than 0.01 mm.

[0056] In one embodiment of the present application, the aperture of the first through hole 1111 is in the range of 1 mm-20 mm.

[0057] The present application also provides a method for manufacturing a piezoelectric actuator, comprising the following steps:

[0058] (1) Preparation of green porcelain tape

[0059] Select piezoelectric ceramic powder, wherein the slurry formula is: including 30wt% to 85wt% of ceramic powder and 15% to 70% of organic matter. The organic matter includes 70wt% to 90wt% of solvent, 5wt% to 25wt% of binder and 0.5wt% to 5wt% of slurry additive; add the ceramic powder and the organic matter into a ball mill container in sequence, and ball mill for 5h to 80h to obtain slurry; then obtain a 20μm-80μm raw porcelain tape by tape casting, and punch holes on the raw porcelain tape.

[0060] (2) Printed electrodes 112

[0061] The pattern of the electrode 112 is printed on the green ceramic tape. The pattern of the electrode 112 can be a circular ring, a square ring or other geometric shapes.

[0062] (3) Preparation of green blocks

[0063] The green ceramic tape with the printed electrode 112 is stacked 40 to 200 layers one by one, and after reaching a certain thickness, it is pressed into a green block by isostatic pressing. The total thickness of the green block ranges from 1 mm to 5 mm.

[0064] (4) Cutting the green block

[0065] The green block is cut into individual green blocks according to the surface cutting line. The surface size of the individual green blocks can be specifically 8.3 mm x 8.3 mm.

[0066] (5) Opening the center hole

[0067] A center hole is opened at the center of each green compact by using a drilling tool, and the smoothness of the inner wall of the center hole should meet the requirements. The diameter of the center hole can be 2.1 mm.

[0068] (6) Debinding sintering

[0069] Each green body with a central hole is placed in a binder removal furnace for heating at a temperature of 300°C to 600°C for 2 hours to 100 hours to remove the colloid in the green body. Afterwards, it is transferred to a sintering furnace, and the electrode 112 and the green porcelain strip are matched and co-fired at a high temperature. The sintering temperature is 700°C to 1300°C and the sintering time is 0.5 hours to 5 hours. Finally, it is sintered into a porcelain block, i.e., the green body of the piezoelectric drive chip 11. The thickness of the green body after sintering is about 0.8mm-4mm, and the diameter of the central hole is about 2mm.

[0070] (7) Grinding

[0071] The blank of the piezoelectric driving chip 11 is ground into a specified shape and size as required.

[0072] (8) Bonding alignment

[0073] The ground piezoelectric driving chips 11 are bonded one by one to form a piezoelectric driving stack 1 .

[0074] (9) Plating the end surface conductive layer 12

[0075] End surface conductive layers 12 are plated at both ends of the piezoelectric drive stack 1 to conduct the electrodes 112 of the same polarity in the piezoelectric drive stack 1. The material of the end surface conductive layer 12 can be specifically metal silver.

[0076] (10) Welding wire

[0077] Positive / negative electrode leads are welded to the end surface conductive layer 12 to connect to an external circuit.

[0078] (11) Polarization treatment

[0079] The piezoelectric drive stack 1 with welded leads is placed in silicone oil for polarization treatment.

[0080] In one embodiment of the present application, the step of opening a center hole on each individual green body can also be arranged after the debinding and sintering step. In another embodiment of the present application, the step of opening a center hole on each individual green body can also be arranged after the bonding and alignment step. The specific position of the step of opening a center hole can be adjusted according to the needs of the product.

[0081] like Fig. 9 As shown, in one embodiment of the present application, when printing the electrode 112, a printing screen is used to print the electrode 112 pattern, and the printing screen has a plurality of electrode 112 patterns arranged in a rectangular array, and the printing plate transfers the ink holes to the printed object through pressure. The printing screen also has positioning holes 2 and cutting line holes 3 surrounding the outside of the rectangular array. Among them, the role of the positioning holes is to serve as a mark point or reference to ensure the alignment accuracy of different layers during alignment. The role of the cutting line is the position based on which the block is cut, ensuring that the product is cut into units according to the designed size.

[0082] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A piezoelectric actuator, characterized in that: include: A plurality of sequentially stacked piezoelectric drive stacks (1), the piezoelectric drive stacks (1) comprising a plurality of sequentially stacked piezoelectric drive chips (11), the piezoelectric drive chips (11) comprising a ceramic insulating layer (111) and an electrode (112), the ceramic insulating layer (111) and the electrode (112) being alternately arranged in sequence; The ceramic insulating layer (111) is provided with a first through hole (1111); the electrode (112) comprises a pole piece portion (1121) and a pin portion (1122); the pole piece portion (1121) is provided with a second through hole (1123) which is coaxially arranged with the first through hole (1111) and has a diameter greater than that of the first through hole (1111); the projection of the pole piece portion (1121) in the thickness direction is within the projection of the outer contour of the ceramic insulating layer (111), and the pin portion (1122) extends to the edge of the outer contour of the ceramic insulating layer (111).

2. The piezoelectric actuator according to claim 1, wherein: The electrode (112) comprises a positive electrode and a negative electrode, the positive electrode and the negative electrode are arranged alternately in sequence, the ceramic insulating layer (111) is arranged between the positive electrode and the negative electrode, the pin portion (1122) of the positive electrode faces one side on the plane of the piezoelectric drive chip (11), and the pin portion (1122) of the negative electrode faces the other side on the plane of the piezoelectric drive chip (11).

3. The piezoelectric actuator according to claim 2, wherein: The piezoelectric drive stack (1) further comprises end surface conductive layers (12) arranged in pairs, wherein the end surface conductive layers (12) arranged in pairs are respectively arranged on both sides of the piezoelectric drive stack (1), one of the end surface conductive layers (12) arranged in pairs is electrically connected to the positive electrode; and the other of the end surface conductive layers (12) arranged in pairs is electrically connected to the negative electrode.

4. The piezoelectric actuator according to any one of claims 1 to 3, characterized in that The minimum distance from the first through hole (1111) to the second through hole (1123) is greater than 0.01 mm.

5. The piezoelectric actuator according to any one of claims 1 to 3, characterized in that: The aperture of the first through hole (1111) ranges from 1 mm to 20 mm.

6. A method for manufacturing a piezoelectric actuator, characterized in that: The steps include: Preparation of green porcelain tape: Piezoelectric ceramic powder is slurried, and then tape-casted to obtain a green porcelain tape of a certain thickness, and holes are punched on the green porcelain tape; Printing electrodes (112): printing electrode (112) patterns on the green porcelain tape; Preparation of green blocks: After the green porcelain tapes are stacked one by one to a certain thickness, they are pressed into green blocks by isostatic pressing; Cutting the green block: cutting the green block into individual green blocks; Opening a center hole: opening a center hole on each individual green body; Debinding and sintering: placing each green body in a debinding furnace for heating to discharge the colloid in the green body; then transferring it to a sintering furnace to sinter it into a piezoelectric drive chip (11); Grinding: grinding the piezoelectric drive chip (11) to a specified shape and size; Bonding alignment: bonding the piezoelectric drive chips (11) one by one to form a piezoelectric drive stack (1); Plating an end surface conductive layer (12): Plating an end surface conductive layer (12) at both ends of the piezoelectric drive stack (1); Welding leads: welding positive and negative electrode leads on the end surface conductive layer (12); Polarization treatment: The piezoelectric drive stack (1) with welded leads is polarized.

7. The method for manufacturing a piezoelectric actuator according to claim 6, wherein: The step of opening a center hole on each individual green compact can be arranged after the step of cutting the green compact, or after the debinding and sintering step, or after the bonding and alignment step.

8. The method for manufacturing a piezoelectric actuator according to claim 6, wherein: When printing the electrode (112), a printing screen is used to print the electrode (112) pattern, wherein the printing screen has a plurality of electrode (112) patterns arranged in a rectangular array, and also has positioning holes and cutting line holes surrounding the outside of the rectangular array.

9. The method for manufacturing a piezoelectric actuator according to claim 6, wherein: When the green porcelain tape is prepared, the thickness of the green porcelain tape ranges from 20 μm to 80 μm.

10. The method for manufacturing a piezoelectric actuator according to claim 6, wherein: When preparing the green block, the number of layers of the green porcelain tape ranges from 40 to 200.

Images