JPH0496286A - Manufacture of laminated piezoelectric element - Google Patents

Abstract

PURPOSE:To reduce an air gap interposed between a piezoelectric plate and metal base and to prevent reductions in piezoelectric characteristics and displacing amount of a piezoelectric element by forming metal thin plates on both side surfaces of the plate by plating or depositing, coating the upper surface with metal paste, alternately laminating the plates and a plurality of metal plates, baking and integrally connecting them. CONSTITUTION:Metal thin layers 1 made of Au, etc., are formed on both side surfaces of a piezoelectric element 1 by plating or depositing. The upper surface of a thin layer 11 is coated with metal paste by screen printing, etc., to form a wet paste layer 12. Piezoelectric plates 1 and metal plates 2 are alternately laminated to form a laminate. The layers 12 formed on both side surfaces of the piezoelectric plate are baked, and the piezoelectric plates and the metal plates are integrally connected. Since the layer 11 formed by plating or depositing is engaged within a recess on the surface of the plate 1, an air gap interposed between the layer 12 and the plate 1 is extremely reduced. When a voltage is applied to the piezoelectric plate, its displacement is absorbed by the air gap to prevent a reduction in the displacing amount as the entire piezoelectric element, and to also prevent a decrease in piezoelectric characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a laminated piezoelectric body used as various actuators.

[Prior Art] As a conventional laminated piezoelectric material, a plurality of piezoelectric plates 8 attached to both surfaces of a metal paste 81 having electrical conductivity and a plurality of metal plates 9 that are electrically connected and serve as electrodes are alternately arranged. JP-A-60-121784 discloses a structure in which a piezoelectric plate 8 and a metal plate 9 are integrally bonded through the adhesive force of a metal paste 81 attached to both surfaces of the piezoelectric plate 8. (Figure 6).

In this laminated piezoelectric body, a metal paste 81 interposed between a piezoelectric plate 8 and a metal plate 9 fills the gap between the two and integrally adheres them.

[Problems to be Solved by the Invention] However, in the laminated piezoelectric body disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 60-121784, since the metal paste 81 is directly applied to both sides of the piezoelectric plate 8, the piezoelectric plate 8 The metal paste 81 is difficult to enter into the recesses on the surface of the piezoelectric plate 8 and a gap is formed between the piezoelectric plate 8 and the metal paste 81. For this reason, when a voltage is applied to the piezoelectric plate 8, the displacement is absorbed by the gap, reducing the amount of displacement of the piezoelectric body as a whole, and the electric field is not applied uniformly, resulting in a decrease in piezoelectric properties.

The present invention has been made in view of the above circumstances, and reduces the gap between the piezoelectric plate and the metal paste,
The purpose is to prevent a decrease in piezoelectric properties and a decrease in displacement of the piezoelectric body.

[Means for Solving the Problems] The method for manufacturing a laminated piezoelectric body of the present invention includes a metal thin layer forming step of forming a metal thin layer on both sides of a piezoelectric plate by plating or vapor deposition, and a paste layer forming step in which a metal paste is applied to the upper surface of the layer to form a wet paste layer; and a plurality of piezoelectric plates on which the metal thin layer and paste layer are formed and a plurality of metal plates are alternately laminated. The method is characterized by comprising a lamination step in which a laminate is formed, and a bonding step in which each piezoelectric plate and each metal plate are integrally joined by firing the laminate.

The metal thin layer forming step is a step of forming a metal thin layer of Ag, Ni, Au, etc. on both surfaces of the piezoelectric body by plating or vapor deposition. The thickness of this thin metal layer is o.

It is preferable that O◯ is 1 to 0.001 mm.

Further, the piezoelectric plate is not particularly limited as long as it has a piezoelectric effect; for example, Ba1i with a perovskite crystal structure
Solid solution of Q3 and PbTiO3 or CaTiQ3, Pb
A plate-shaped plate formed from a piezoelectric ceramic such as a solid solution of Zro3 and PbT i 03 (PZT) is used as in the conventional one.

The paste layer forming step is a step of applying a metal paste by screen printing or the like to the upper surface of the metal thin layer formed on both sides of the piezoelectric structure in the metal thin layer forming step to form a groove-shaped paste layer. The thickness of this paste layer is 0.005~
It is preferable to cover it by 0.02 mm.

The lamination step is a step of alternately laminating a plurality of piezoelectric plates and metal plates on which the metal thin layers and paste layers are formed to form a laminate. This metal plate is made of Cu, SUS, etc., and is similar to the conventional metal plate in which a protrusion with a tip bent in the axial direction is formed on the outer periphery of the metal plate and extends radially outward. can. Further, the piezoelectric plates and the metal plates are alternately stacked so that the protrusions of the metal plates alternately face in opposite directions, and the protrusions of the metal plates separated by one are at the same angular position.

The bonding step is a step of firing the laminate to integrally bond each piezoelectric plate and each metal plate. This firing is 400 ~
It is applied under the conditions of 850'C110 to 60 minutes. In this joining step, wet paste layers formed on both sides of the piezoelectric plates are fired, thereby integrally joining each piezoelectric plate and each metal plate.

Further, it is preferable that the paste layer is dried at around 100° C. for 10 to 30 minutes before firing.

Further, the method for manufacturing a laminated piezoelectric body of the present invention includes the above-mentioned thin metal layer forming step, the above-mentioned paste layer forming step, a paste layer baking step of baking a paste layer of the piezoelectric body, and a step in which the paste layer is baked. The method may also include a lamination step of alternately laminating a plurality of piezoelectric plates and a plurality of metal plates to form a laminate.

In this case, it is preferable to further form an electrically conductive adhesive or solder layer on the upper surface of the paste layer of each piezoelectric plate between the paste layer firing step and the lamination step.

When a solder layer is formed, each piezoelectric plate and each metal plate can be integrally joined by heating and melting and bonding the solder after the lamination process.

[Operations and Effects of the Invention] In the method for manufacturing a laminated piezoelectric body of the present invention, a thin metal layer is formed on both sides of the piezoelectric plate by plating or vapor deposition before applying a metal paste to both sides of the piezoelectric plate. This thin metal layer formed by plating or vapor deposition enters into the recesses on the surface of the piezoelectric plate. Therefore, the gap between the piezoelectric plate and the paste layer coated on the upper surface of the thin metal layer is greatly reduced.

Therefore, when a voltage is applied to the piezoelectric plate, it is possible to prevent the displacement from being absorbed by the gap portion and the displacement amount of the piezoelectric body as a whole decreasing. Further, deterioration of piezoelectric properties due to the voids can also be prevented.

In addition, in the method for manufacturing a laminated piezoelectric body of the present invention, since a thin metal layer is formed on the piezoelectric plate by plating or vapor deposition,
The adhesive strength between the piezoelectric plate and the thin metal layer is strong, and an electric field is applied uniformly to the piezoelectric plate. Therefore, after forming a piezoelectric thin metal layer, it is possible to check the characteristics and defective products of each piezoelectric plate, and it is possible to improve the rate of non-defective products.

[Example] Hereinafter, this will be explained in detail using examples.

(Example 1) (Metal thin layer forming process) Made of PZT piezoelectric plate, diameter 15 mm, thickness 0°5 mm
A large number of disc-shaped piezoelectric plates 1 were prepared, and ACI plating was applied to both sides of each piezoelectric plate 1 to form a thin metal layer 11 having a thickness of 0.001 mm. Characteristics such as withstand voltage, displacement, capacitance, presence of cracks, etc. were checked for each piezoelectric plate 1 on which the metal thin layer 11 was formed, and defective products were removed. The electrical properties of the piezoelectric plate 1 formed with the above metal thin layer] 1 are directly A.
The electrical properties are superior to those of a piezoelectric plate printed with g-paste and fired (see table).

Table (Paste layer forming step) Act paste was screen printed on the metal thin layer 11 of each of the piezoelectric plates 1 to form a wet paste layer 2 having a thickness of 0.01 mm. Then, each piezoelectric plate 1 was dried at 100° C. for 20 minutes.

(Lamination process) A substantially disc-shaped metal plate 2 made of Cu and having a diameter of 15 mm and a thickness of 0.03 mm was used. On the outer peripheral edge of this metal plate 2, a protrusion 21 having a width of 2 mm and whose tip is bent in the axial direction extends radially outward by Q and 3 mm. 80 layers of each piezoelectric plate 1 and each metal plate 2 are alternately laminated so that the protrusions 21 of the metal plates 2 alternately face opposite directions, and the protrusions 21 of the metal plates 2 separated by one are at the same angular position. A laminate 3 was thus formed.

(Joining process) The above laminate 3 is fired at 500°C for 30 minutes to form each piezoelectric plate 1.
and each metal plate 2 were integrally joined.

After that, the lead plates 5a and 5b, to which the lead wires 4a and 4b connected to the positive and negative electrodes of a power source (not shown) are welded, are attached to the side surface of the laminate 3. A coating layer (not shown) was formed to obtain a laminated piezoelectric body.

When a voltage of 500 V was applied to the laminated piezoelectric material according to Example 1 under a load of 100 kClf, it was displaced by 42 μm in the axial direction. This value was 5% higher than the displacement of 40 μm in a conventional laminated piezoelectric material in which ACI paste was printed directly on a piezoelectric plate. This is because in the laminated piezoelectric body according to the first embodiment, the metal thin layer 11 formed by plating on both sides of the piezoelectric plate 1 enters into the recess on the piezoelectric plate 1, and the upper surface of this metal thin layer 11 This is because the gap between the paste layer 12 applied to the piezoelectric plate 1 and the piezoelectric plate 1 is extremely reduced, so that the amount of displacement absorbed by the gap is reduced.

In addition, in the laminated piezoelectric body according to the first embodiment, after forming the metal thin layer 11 on each piezoelectric plate 1 by plating, the piezoelectric plate
Characteristics and defects can be checked for each sheet, and the rate of non-defective items can be improved.

Furthermore, in the laminated piezoelectric body according to the first embodiment, since each piezoelectric plate 1 and each metal plate 2 are integrally joined by the paste layer 12, the metal plate 2 can be moved by relative movement in the radial direction.
Since they do not directly face each other, there is no risk of electrical discharge due to dielectric breakdown in the air.

(Example 2) (Metal thin layer forming step, paste layer forming step) The metal thin layer forming step and paste layer forming step were performed in the same manner as in Example 1 above.

(Paste layer firing process) Each piezoelectric plate 1 subjected to the above paste layer forming process was
It was baked at ℃ for 30 minutes.

(Lamination process) Each piezoelectric plate 1 and metal plate 2 on which this paste layer 12 is fired
A laminate 3 was obtained by laminating 80 layers alternately in the same manner as in Example 1 above.

After that, the lead wires 4a, 4b and the lead plates 5a, 5b are attached in the same manner as in Example 1, and an insulating coating layer made of silicone resin is formed on the side surface of the laminate 3. As a body.

This laminated piezoelectric material also has a metal thin layer 11 formed in advance by plating on both sides of the piezoelectric plate 1, so that it is possible to prevent a decrease in the displacement 1, as in the case of Example 1, and to make each piezoelectric plate unique. By checking for defective products, it is possible to improve the rate of non-defective products.

Furthermore, since the paste layer 12 is fired and in a solid state during the lamination process, workability is excellent.

(Example 3) Using a metal plate 2 in which a solder layer 6 having a thickness of 0.003 mm was formed by plating solder containing Sn as a main component on both sides of the disc-shaped portion of each metal plate 2, A metal all forming step, a paste layer forming step, by the same method as in Example 2 above,
A paste layer firing process and a lamination process were performed.

Then, after applying a heat treatment of 230'C for 15 minutes with a load of 100kC]f applied to the laminate, each piezoelectric plate 1 and each metal plate 2 are melted and bonded by a solder layer 6 by returning to room temperature. and became integrated. Finally, as in Example 1, lead wires 4a, 4b and lead plates 5a, 5b are attached, a coating layer made of silicone resin is formed on the side surface of the laminate, and the laminate piezoelectric body according to Example 3 is assembled. did.

In this laminated piezoelectric body, since the solder layer 6 is formed by plating, the solder layer 6 can be made thinner than when a paste is attached by screen printing. Therefore, even if the laminated body is pressurized in order to eliminate voids after lamination and increase the eating power, the solder will not protrude to the side surface of the piezoelectric plate 1. Moreover, even if it protrudes from the side of the piezoelectric plate 1,
Since the solder has poor wettability with the piezoelectric plate 1, the solder does not adhere to the side surfaces of the piezoelectric plate 1. Therefore, the laminated piezoelectric body of Example 3 is similar to Example 1 and Example 2.
In addition to the effects of the laminated piezoelectric material described above, 7JO also has the effect of reducing the risk of conduction between the positive electrode and the negative electrode.

[Brief explanation of drawings]

FIG. 1 is a front view showing the schematic structure of the laminated piezoelectric body of Example 1, FIG. 2 is a perspective view of a piezoelectric plate attached to the laminated piezoelectric body, and FIG. 3 is a metal plate attached to the laminated piezoelectric body. A perspective view of the plate, FIG. 4 is a perspective view illustrating a state in which the piezoelectric plate and metal plate of the laminated piezoelectric body are laminated. FIG. 5 is a front view showing the schematic structure of the laminated piezoelectric body of Example 3. FIG. 6 is a front view showing a schematic configuration of a conventional laminated piezoelectric body. 1-...Piezoelectric plate 3...Laminated body 11...Metal thin layer 2...-Metal plate 6...Solder layer 12...Paste layer Patent applicant Toyota Motor Corporation

Claims (2)

[Claims] (1) A thin metal layer forming step of forming a thin metal layer on both sides of the piezoelectric plate by plating or vapor deposition, and applying a metal paste to the top surface of the thin metal layer of the piezoelectric plate to form a wet paste layer. a step of forming a paste layer; a laminating step of forming a laminate by alternately laminating a plurality of piezoelectric plates on which the thin metal layer and the paste layer are formed and a plurality of metal plates; and firing the laminate. A method for manufacturing a laminated piezoelectric material, comprising the steps of: integrally joining each piezoelectric plate and each metal plate. (2) A thin metal layer forming step of forming a thin metal layer on both sides of the piezoelectric plate by plating or vapor deposition, and applying a metal paste to the top surface of the thin metal layer of the piezoelectric plate to form a wet paste layer. a paste layer forming step; a paste layer firing step of firing the paste layer of the piezoelectric plate; and forming a laminate by alternately stacking a plurality of piezoelectric plates with fired paste layers and a plurality of metal plates. 1. A method for manufacturing a laminated piezoelectric material, comprising: a lamination step.