Piezoelectric ceramic composite structure based on all-electrode polarization

Abstract

The utility model relates to the technical field of piezoelectric ceramics, in particular to a piezoelectric ceramic composite structure based on all-electrode polarization. A piezoelectric ceramic composite structure based on all-electrode polarization comprises a polarized piezoelectric ceramic layer, a first surface of the piezoelectric ceramic layer is provided with a first electrode, a second surface of the piezoelectric ceramic layer is provided with a second electrode, the surface of the first electrode is coated with an insulating paint layer, and the insulating paint layer is coated with a second electrode. The surface of the second electrode is bonded and fixed with a conductive layer through an epoxy resin bonding layer, the conductive layer is provided with an insulating circuit board, the shape of the conductive layer is consistent with that of the second electrode, the edge of the insulating circuit board is provided with a groove, the edge of the conductive layer is provided with a welding area extending into the groove, and the welding area is provided with a plurality of grooves. The welding area and the conductive layer are integrally formed, and the welding area is used for conducting wire welding. According to the utility model, all-electrode polarization is adopted, so that the working voltage is increased, and the problem of ceramic chip breakdown caused by electrode stress concentration due to flanging is solved.

Description

Technical Field

[0001] This utility model relates to the field of piezoelectric ceramic technology, and in particular to a piezoelectric ceramic composite structure based on all-electrode polarization. Background Technology

[0002] Currently, traditional piezoelectric ceramic elements typically use metal foil (such as copper foil or silver foil) or printed electrodes (such as silver paste) as electrode layers. During the fabrication process, due to the difference in thermal expansion coefficients between the electrode material and the piezoelectric ceramic substrate, uneven interfacial stress distribution occurs during high-temperature sintering or cooling, leading to edge curling (warping, curling) at the electrode edges. Furthermore, electrode curling disrupts the uniformity of the polarization electric field distribution, resulting in incomplete polarization of the piezoelectric ceramic layer, manifested as a decrease in the piezoelectric constant (d33) and an increase in dielectric loss. Under high-voltage operating conditions, electric field concentration easily forms in the curled area, triggering localized breakdown or arcing, severely limiting the reliability of the element in high-voltage applications (such as piezoelectric transformers and high-power ultrasonic transducers).

[0003] Some piezoelectric ceramic components (such as ultrasonic atomizing plates, ultrasonic sensors, etc.) need to be connected to external circuits by wire bonding. However, the stress concentration on the surface of traditional electrodes makes the solder joints easy to fall off. If the temperature of the soldering gun tip is too high, it may even burn off the silver layer. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a piezoelectric ceramic composite structure based on all-electrode polarization.

[0005] The technical implementation scheme of this utility model is as follows: a piezoelectric ceramic composite structure based on full electrode polarization, comprising a piezoelectric ceramic layer with complete polarization, a first electrode on a first surface of the piezoelectric ceramic layer, a second electrode on a second surface of the piezoelectric ceramic layer, an insulating varnish coating on the surface of the first electrode, a conductive layer bonded and fixed to the surface of the second electrode by an epoxy resin adhesive layer, an insulating circuit board on the conductive layer, the shape of the conductive layer being consistent with the shape of the second electrode, a groove being provided on the edge of the insulating circuit board, and a welding area extending into the groove being provided on the edge of the conductive layer, the welding area being integrally formed with the conductive layer for wire welding.

[0006] Preferably, the insulating circuit board is made of FR4 material with a thickness of 0.5-1.5mm, and the conductive layer is a copper foil layer with a thickness of 20-50μm, which is formed by etching to form a conformal structure with the second electrode.

[0007] Preferably, the insulating varnish layer is made of polyimide or epoxy resin material, with a thickness of 15-30 μm, a withstand voltage rating of ≥2kV, and completely covers the edge of the first electrode to prevent electric field concentration.

[0008] Preferably, the curing conditions for the epoxy resin adhesive layer are: temperature 100-130℃, pressure 1.0-1.8MPa, time 40-90 minutes, and the shear strength after curing is ≥8MPa.

[0009] The present invention has the following advantages: 1. The present invention adopts full electrode polarization, which increases its working voltage and solves the problem of electrode stress concentration caused by flipping, which leads to ceramic sheet breakdown.

[0010] 2. This utility model adopts a piezoelectric ceramic element with an integrated electrode structure on an insulated circuit board, which has high voltage isolation and wire bonding interface functions. It is especially suitable for high-frequency high-voltage power supply modules or piezoelectric ceramic actuators that require direct wire bonding (such as ultrasonic transducers and precision displacement platforms). At the same time, it solves the problem of the silver layer being burned off due to excessively high temperature of the soldering gun head. Attached Figure Description

[0011] Figure 1 This is a three-dimensional structural layered diagram of the present invention.

[0012] Figure 2 This is a three-dimensional structural assembly drawing of the present invention.

[0013] In the above figures: 1-piezoelectric ceramic layer, 2-first electrode, 3-second electrode, 4-insulating varnish layer, 5-insulating circuit board, 6-epoxy resin adhesive layer, 7-conductive layer, 8-welding area. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] Example 1: A piezoelectric ceramic composite structure based on all-electrode polarization, referring to... Figures 1-2 The device includes a piezoelectric ceramic layer 1 with complete polarization. A first electrode 2 is provided on the upper surface of the piezoelectric ceramic layer 1, and a second electrode 3 is provided on the lower surface of the piezoelectric ceramic layer 1. An insulating varnish layer 4 is coated on the upper surface of the first electrode 2. A conductive layer 7 is bonded and fixed to the lower surface of the second electrode 3 by an epoxy resin adhesive layer 6. An insulating circuit board 5 is provided on the conductive layer 7. The shape of the conductive layer 7 is consistent with the shape of the second electrode 3. A groove is provided on the edge of the insulating circuit board 5. A welding area 8 extending into the groove is provided on the edge of the conductive layer 7. The welding area 8 is integrally formed with the conductive layer 7 and is used for wire welding.

[0016] Preferably, the insulating circuit board 5 is made of FR4 material with a thickness of 0.5-1.5mm, and the conductive layer 7 is a copper foil layer with a thickness of 20-50μm, which is formed by etching to form a conformal structure with the second electrode 3.

[0017] Preferably, the insulating varnish layer 4 is made of polyimide or epoxy resin material, with a thickness of 15-30 μm, a withstand voltage rating of ≥2kV, and completely covers the edge of the first electrode 2 to prevent electric field concentration.

[0018] Preferably, the curing conditions for the epoxy resin adhesive layer 6 are: temperature 100-130℃, pressure 1.0-1.8MPa, time 40-90 minutes, and the shear strength after curing is ≥8MPa.

[0019] Working principle: Silver paste is screen-printed on both surfaces of the piezoelectric ceramic layer 1 to form the first electrode 2 and the second electrode 3; then the printed piezoelectric ceramic layer 1 is polarized, and the insulating varnish layer 4 is coated on the surface of the first electrode 2, which is cured to form a full-coverage insulating protection; the conductive layer 7 and the welding area 8 are prepared on the insulating circuit board 5 by etching process, and the epoxy resin adhesive layer 6 is coated on the surface of the second electrode 3. The insulating circuit board 5 and the piezoelectric ceramic layer 1 are aligned and bonded together, and then cured by hot pressing to form an integrated structure. This structure has high voltage isolation and wire bonding interface functions, and is especially suitable for high-frequency high-voltage power modules or piezoelectric ceramic actuators that require direct wire bonding (such as ultrasonic transducers and precision displacement platforms).

[0020] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made using the content of this utility model specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A piezoelectric ceramic composite structure based on the polarization of the whole electrode, characterized by: The device includes a piezoelectric ceramic layer (1) with polarization completed. A first electrode (2) is provided on the first surface of the piezoelectric ceramic layer (1), and a second electrode (3) is provided on the second surface of the piezoelectric ceramic layer (1). An insulating varnish layer (4) is coated on the surface of the first electrode (2). A conductive layer (7) is bonded and fixed to the surface of the second electrode (3) by an epoxy resin adhesive layer (6). An insulating circuit board (5) is provided on the conductive layer (7). The shape of the conductive layer (7) is consistent with the shape of the second electrode (3). A groove is provided on the edge of the insulating circuit board (5). A welding area (8) extending into the groove is provided on the edge of the conductive layer (7). The welding area (8) is integrally formed with the conductive layer (7) and is used for wire welding.

2. A piezoelectric ceramic composite structure based on the polarization of the whole electrode according to claim 1, characterized in that: The insulating circuit board (5) is made of FR4 material with a thickness of 0.5-1.5mm, and the conductive layer (7) is a copper foil layer with a thickness of 20-50μm, which is formed by etching process to form a conformal structure with the second electrode (3).

3. A piezoelectric ceramic composite structure based on the polarization of the whole electrode according to claim 1, characterized in that: The insulating varnish layer (4) is made of polyimide or epoxy resin material, with a thickness of 15-30μm and a withstand voltage rating of ≥2kV, and completely covers the edge of the first electrode (2) to prevent electric field concentration.

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