JPH0476968A - Manufacture of laminated piezoelectric element - Google Patents

Abstract

PURPOSE:To accurately position a pellet in a prescribed part at a lamination operation and to manufacture a laminated piezoelectric element with good reliability by a method wherein, when the laminated piezoelectric element is manufactured, an auxiliary protruding piece is formed at a metal electrode whose outside diameter is smaller than that of the pellet. CONSTITUTION:A metal electrode 5, to be inserted in a pellet 1, in which only one electrode extraction piece 5a has been formed is manufactured; at least one auxiliary protruding piece 5b which can be removed by a slight external force is formed at its peripheral edge part. A groove 73 used to accept the auxiliary protruding piece 5b formed at the metal electrode 5 is formed at a lamination metal mold 7 into which the pellet 1 and the metal electrode 5 are inserted for an assembly operation. Thereby, the pellet is inserted into the lamination metal mold 7 and the metal electrode 5 is inserted into the lamination metal mold 7 while the electrode extraction piece 5a and the auxiliary protruding piece 5b are being aligned with grooves. Then, the movement of the metal electrode 5 inserted into the lamination metal mold 7 is limited by the electrode extraction piece 5a and the auxiliary protruding piece 5b before a lamination and bonding process or during the lamination and bonding process. As a result, it is possible to prevent the metal electrode 5 from being displaced from a printed electrode 1a on the pellet before a bonding process or during the bonding process.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a laminated piezoelectric element, and in particular, to a method for manufacturing a laminated piezoelectric element, in particular, a piezoelectric element is laminated with a partial electrode sandwiched between the laminated surfaces, and an electrode provided on the partial electrode is laminated. The present invention relates to a method of manufacturing a laminated piezoelectric element in which every other layer is connected to an external electrode on the same side.

[Prior Art] A piezoelectric element having a multilayer capacitor structure is an excellent actuator that generates large distortion at low voltage. For this reason,
Manufacturing equipment for various electronic components such as semiconductors that perform microfabrication,
This piezoelectric actuator is used in optical devices and the like that require minute positioning. In addition, a stacked piezoelectric actuator has been put into practical use, in which such piezoelectric elements and electrode plates are alternately stacked, and the electrodes located above and below each layer are connected to different voltage sources to increase the amount of strain generated. In recent years, laminated piezoelectric actuators have also come to be used as control parts for dot printer heads and the like.

By the way, in the stacked piezoelectric actuator, since the electrodes of every other layer are connected to the same power source as described above, if the piezoelectric element and the electrode plate have the same area, two electrodes are connected to the same power source.
Since the end of the electrode plate (or electrode layer) that is connected to another power supply is exposed between two electrode plates (or electrode layers), it is necessary to insulate this end of opposite polarity to prevent short circuits. be.

Therefore, in order to improve the insulation resistance, the electrode plates sandwiched between the piezoelectric elements are made into partial electrodes that are one size smaller in area than the piezoelectric elements.

6 to 8 show a conventional method of manufacturing a laminated piezoelectric element using such partial electrodes. Figure 6 shows the shapes and dimensional relationships of the thin piezoelectric plates (hereinafter referred to as pellets) 1, metal electrodes 2, and insulating plates (shims) 3 attached above and below the pellets 1 and the metal electrodes 2, which constitute the laminated piezoelectric element. It shows.

Pellets 1 are, for example, lead zirconate titanate P b (
Tit Zr+-x ) 03 (X = 0.4~0
．． 6 indicates the molar ratio], and the thickness t =
It has a disc shape of 0.5 mm and a diameter of 30 mm, and printed electrodes 1a are printed on the upper and lower surfaces. The metal electrode 2 is superimposed on the printed electrode 1a of the pellet 1, is slightly smaller than the pellet 1, and has a thickness of t=
The electrode length is approximately 0.02 mm, and an electrode extraction piece 2a for external extraction is provided at one location on the periphery. Also, Sim 3
is made from insulators such as zirconia and alumina.
It has a disk shape with a thickness of about t-2.0 mm, and its diameter is the same as that of the pellet 1.

When manufacturing a laminated piezoelectric element using these pellets 1-1, metal electrodes 2, and shims 3, as shown in FIG.
After placing shim 3 at the bottom, pellet 1 and metal electrode 2
A predetermined number of metal electrodes, for example 40 metal electrodes, are stacked alternately so that the electrode extraction pieces 2a of the metal electrodes 2 alternately protrude to the opposite side, and the shim 3 is also stacked on top. The stacked pellets 1 and metal electrodes 2 are crimped and integrated by hot pressing, and then the metal electrodes 2 are bent in the middle, and the metal electrodes 2 protruding from the same side are connected to the external electrodes 4 by resistance welding or the like.

Note that in order to align the positions of the pellet 1 and the metal electrode 2 and stack them, the pellet 1 and the metal electrode 2 are usually stacked.
A lamination mold 8 as shown in FIG. 8 is used for lamination. This laminated mold 8 consists of a male mold 8A and a female mold 8B that can be separated, and when the two are put together, a pellet 1 is formed in the main body.
A cylindrical portion 81 for accommodating the electrode extraction piece 2a and a groove portion 82 for inserting the electrode extraction piece 2a are formed. Therefore, when manufacturing a laminated piezoelectric element, the pellet 1 is inserted into the cylindrical portion 8I,
Insert the metal electrode 2 while alternately aligning the electrode extraction pieces 2a with the grooves 82 on the opposite side, and insert the printed electrode l of the pellet I.
The metal electrode 2 is just laminated on top of a.

[Problem to be solved by the invention]

However, in the conventional manufacturing method of a laminated piezoelectric element using a metal electrode 2 provided with an electrode extraction piece 2a at only one location,
After inserting the pellet 1 and the metal electrode 2 into the lamination mold 8 and before or during the lamination adhesion process, the metal electrode 2 moves within the lamination mold 8, as shown in FIG. The metal electrode 2 shifts from above the printed electrode Ia of the pellet 1, and the peripheral edge of the metal electrode 2 becomes a pellet in the laminated portion of the laminated piezoelectric element) 1
As a result, the withstand voltage decreases, and there is a problem in that the metal electrode 2 near the peripheral edge of the pellet 1 is damaged due to a discharge short circuit.

This is because a certain amount of clearance is provided between the electrode extraction piece 2a of the metal electrode 2 and the positioning groove 82 of the laminated mold 8 in the width direction of the electrode extraction piece 2a so that the metal electrode 2 can be inserted smoothly. This is because For example, if this gap is 0.
06 mm, the length of the electrode extraction piece 2a is generally as short as, for example, about 3 mm, and the displacement of the main body portion would be several times as large.

The present invention has a shape smaller than a piezoelectric element as an internal electrode.
We have solved the problems in the conventional manufacturing method of a laminated piezoelectric material of the type in which a metal electrode is provided with an electrode extraction piece in two places, and the electrode extraction piece of this metal electrode is bent and connected to an external electrode. To accurately position a metal electrode having an outer diameter smaller than that of a pellet at a predetermined portion of the pellet during lamination when manufacturing a piezoelectric element, and to manufacture a laminated piezoelectric element with good reliability, thereby improving productivity and reducing costs. The purpose of the present invention is to provide a method for manufacturing a laminated piezoelectric element that can perform the following steps.

[Means to solve the problem]

The method for manufacturing a laminated piezoelectric element of the present invention that achieves the above object includes a piezoelectric plate made of a piezoelectric material, an area one size smaller than the laminated surface of the piezoelectric plate, and an electrode extraction piece on the peripheral edge.
a metal electrode plate having at least one auxiliary protrusion that can be separated by a slight external force;
The piezoelectric plates and metal electrodes are arranged alternately in a laminated mold provided with grooves for the electrode extraction pieces and grooves for the auxiliary projecting pieces, and the extraction pieces protrude to the opposite side every other layer. The feature is that a plurality of metal electrodes are inserted and stacked, and after stacking, the auxiliary protrusion of each metal electrode is removed by external force, and the electrode extraction piece is connected to an external electrode to form a stacked piezoelectric element.

(Function) In the method for manufacturing a laminated piezoelectric element of the present invention, a metal electrode inserted between pellets is provided with an electrode extraction piece at only one location, and removed by applying a slight external force to the periphery of the metal electrode. At least one auxiliary protruding piece is provided if possible.Also, in the laminated mold that is assembled by inserting the pellet and metal electrode, the auxiliary window piece holder provided on this metal electrode forms a groove for insertion. Therefore, if the pellet is inserted into the lamination mold as usual, and the metal electrode is inserted into the lamination mold while aligning the electrode extraction piece and the auxiliary protrusion with the groove, the metal electrode inserted into the lamination mold will be inserted into the lamination mold. Before bonding or during the lamination bonding process, the movement of the electrode is restricted by the electrode extraction piece and the auxiliary protrusion.As a result, the metal electrode is prevented from shifting from the printed electrode on the pellet before bonding or during the bonding process. Ru.

〔Example〕

Embodiments of the method for manufacturing a laminated piezoelectric element of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals are given to the same members used in manufacturing the laminated piezoelectric element as in the past. and explain.

FIGS. 1(a) and 1(b) show the shape and dimensional relationship of the pellet 1 and the metal electrode 5 of one embodiment used in the method of manufacturing a laminated piezoelectric element of the present invention.

Pellet 1 is the same as the one previously used, and is lead zirconate titanate Pb (TixZrl-x)0+Cx
= 0.4 to 0.6], the main component is t-0.5IllII+ in thickness, approximately 30 mm in diameter, and printed electrodes 1a are baked on the top and bottom surfaces. The attachment is formed. On the other hand, the metal electrode 5 used in the present invention is
Printed electrode 1 of pellet 1, one size smaller than pellet 1
The metal electrode 2 has a thickness of about t = 0.02 mm and is the same as the conventional metal electrode 2 up to the point where an electrode extraction piece 5a for external extraction is provided at one location on the periphery. The metal electrode 5 used in the present invention differs from the metal electrode 2 in that an auxiliary protrusion 5b is provided on the peripheral edge of the metal electrode 5.

Although not shown, the shim 3 is also made of an insulator such as zirconia or alumina as in the past, and has a thickness t = 2.
It may be formed into a disk shape having the same diameter as the pellet 1, with a diameter of about 0 mm.

In this embodiment, the auxiliary protruding piece 5b is provided so as to protrude from the protruding position of the electrode extraction piece 5a at a position 90° away from the center point of the metal electrode 5, and is formed integrally with the metal electrode 5. ing. The auxiliary protrusion 5b has approximately the same width as the electrode extraction piece 5a on the free end side, and the width of the auxiliary protrusion 5b near the peripheral edge of the metal electrode 5 is narrowed to form a membrane rupture part with a slight width. 5c so that it is connected to the metal electrode 5. Note that it is desirable that the auxiliary projecting piece 5b has a draft angle, and it is more desirable that a fluorine-based mold release agent be applied to the surface.

Further, in the present invention, the metal electrode 5 configured as described above is used.
Depending on the situation, a laminated mold 7 as shown in FIG. 2 is used. This laminated mold 7 consists of a male mold 7A and a female mold 7B that can be separated, and when they are combined, the main body has a cylindrical part 71 that accommodates the pellet 1, and a groove part 7 into which the electrode extraction piece 5a is inserted.
2, and a groove 73 into which the auxiliary protrusion 5b is inserted is formed. Note that, as shown in FIG. 1(a), since the auxiliary protrusion 5b is provided in a direction perpendicular to the electrode extraction piece 5a, only one groove 73 is required to be formed in the laminated mold 7.

Next, a method for manufacturing a laminated piezoelectric element using the member configured as described above will be described.

First, after placing the shim 3 at the lowest part of the cylindrical part of the laminated mold 7 that combines the male mold 7A and the female mold 7B, the pellets 1 and the metal electrodes 5 are alternately placed as shown in FIG. Metal electrode 5
are inserted so that the electrode extraction pieces 5a alternately protrude to the opposite side. At this time, the metal electrodes 5 shown in FIG. 1(a) are used by turning over every other metal electrode, and the electrode extraction pieces 5a are inserted into the grooves 72 and the auxiliary protrusions 5b are aligned with the grooves 73. In this way, for example, about 40 pellets 1 and metal electrodes 5 are each stacked, and the shim 3 is stacked on top.

Thereafter, the stacked pellets 1 and metal electrodes 2 are bonded and integrated by hot pressing. At this time, the metal electrode 5
As shown in the figure, since the metal electrode 5 is positioned in the laminated mold 7 by the electrode take-out piece 5a and the auxiliary projection piece 5b, it is difficult for the metal electrode 5 to be misaligned, and even if it does, the electrode take-out piece 5a Compared to conventional metal electrodes 5 that are positioned only by hand, the amount of positional deviation is extremely small, and the withstand voltage is as designed, ensuring quality.

In addition to the electrode extraction piece 5a, the auxiliary protrusion 5b protrudes from the laminated piezoelectric element laminated in this way.
As shown in FIG. 4, the auxiliary protrusion 5b is pulled from the outside of the laminated piezoelectric element in the direction of the arrow, and the auxiliary protrusion 5b is pulled into the membrane-ruptured area 5c.
It is separated from the metal electrode 5 at the part. At this time, the auxiliary protrusion 5
If b has a draft angle, it will be easier to separate the auxiliary protrusion 5b from the metal electrode 5, and furthermore, a mold release agent such as a fluorine-based material can be used to separate the auxiliary protrusion 5b from the metal electrode 5.
If it is coated on the surface of the metal electrode 5, it will be easier to separate it, but the experimental results show that the auxiliary protrusion 5b can be separated from the metal electrode 5 without any problem even if there is no draft angle or a release agent is not coated. We were able to.

After all the auxiliary protrusions 5b are removed from the laminated piezoelectric element, the metal electrode 5 is bent in the paint and the metal electrode 5 protruding on the same side is connected to the external electrode 4 by resistance welding, etc., and the laminated piezoelectric element is A device is manufactured.

Incidentally, the area of the part of the auxiliary protrusion 5b where the membrane rupture part 5c is separated is determined by, for example, the thickness of the stainless steel metal electrode 5 being 0.
02 mm, and the width of the membrane rupture part 5c is 0.5 mm,
0.01 mm2, and even a member with a strong tensile strength of 150 kg/mm2 can rupture at 1.5 kg.

In addition, according to the results of an actual experiment, the membrane rupture part 5c was able to rupture with a tensile force of 1 kg or less. In this way, since only a very small force is required to separate the auxiliary protrusion 5b from the metal electrode 5, there is no adverse effect on the main body of the laminated piezoelectric element or the adhesive surface.

FIG. 5 shows another embodiment of the metal electrode 5 used in the method of manufacturing a laminated piezoelectric element of the present invention. Figure 5 (a
The metal electrode 5 shown in ) has a wide auxiliary protrusion 5b and two membrane rupture parts 5c to stabilize positioning. The metal electrode 5 shown in FIG. 5 (1)) has a T-shaped auxiliary protrusion 5b at the tip of the conventional electrode extraction piece 5a, and the T-shaped part prevents the metal electrode 5 from shifting. A perforated membrane rupture portion 5c is provided at the boundary between the auxiliary protrusion 5b and the electrode extraction piece 5a by means such as etching. The metal electrode 5 in FIG. 5(C) is provided with an auxiliary protrusion 5b on the opposite side of the electrode extraction piece 5a, and in this embodiment there is no need to create a new positioning groove in the laminated mold. , the same laminated mold 8 as the conventional one can be used.

5(d) and (e) show the metal electrode 5 provided with two auxiliary protrusions 5bl and 5bz, and FIG. , when the viscosity of the adhesive is high during the compression process of the laminate, and when extruding the adhesive vertically, in the unlikely event that a uniform surface pressure is not applied, the lateral force will be applied to the metal electrode. 5, the metal electrode 5 is prevented from shifting and the positioning accuracy is increased.

The above is an example of the shape of the metal electrode 5 used in the method of manufacturing a laminated piezoelectric element of the present invention, and the shape of the metal electrode 5 used in the present invention is not limited to these shapes.

In such a laminated piezoelectric element manufactured by the method of the present invention, displacement of the metal electrodes 5 after lamination is prevented, so a decrease in withstand voltage and damage due to discharge short circuits at the periphery of the metal electrodes are also prevented. .

[Effects of the Invention] As explained above, according to the method for manufacturing a laminated piezoelectric element of the present invention, when manufacturing a laminated piezoelectric element, a metal electrode having an outer diameter smaller than that of the pellet is correctly placed in a predetermined portion of the pellet during lamination. Since the laminated piezoelectric elements can be manufactured reliably by positioning, there is an effect that productivity can be improved and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the dimensions and shapes of metal electrodes and pellets used in the method of manufacturing a multilayer piezoelectric element of the present invention, and FIG. 2 is a perspective view showing one step of the method of manufacturing a multilayer piezoelectric device of the present invention. , FIG. 3 is a plan view showing one step of the method for manufacturing a laminated piezoelectric element of the present invention, FIG. 4 is an explanatory diagram showing another step of the method for manufacturing a laminated piezoelectric element of the present invention, and FIG. a) to (f) are plan views showing the shapes of other embodiments of metal electrodes used in the method for manufacturing a laminated piezoelectric element of the present invention; FIG. 6 is a plan view showing the shape of a metal electrode used in a conventional method for manufacturing a laminated piezoelectric element A plan view showing the shapes and dimensional relationships of pellets, metal electrodes, and shims. Fig. 7 is a perspective view showing the configuration of a conventional multilayer piezoelectric element. Fig. 8 is a step in a conventional method for manufacturing a multilayer piezoelectric element. FIG. 9 is a plan view showing problems in the conventional method of manufacturing a laminated piezoelectric element. DESCRIPTION OF SYMBOLS 1... Pellet 2... Metal electrode, 2a... Electrode extraction piece, 3... Shim, 4... External electrode, 5... Metal electrode, 5a... Electrode extraction piece, 5b, 5b+~5b,... Auxiliary protrusion, 7.8...
Laminated mold, 7L 81... Cylinder part, 72, 82.83... Groove part.

Claims (1)

[Scope of Claims] A piezoelectric plate made of a piezoelectric material, which has an area slightly smaller than the laminated surface of the piezoelectric plate, has one electrode extraction piece on the peripheral edge, and has an auxiliary protrusion that can be separated by a slight external force. A metal electrode plate provided at at least one location is formed, and the piezoelectric plate and the metal electrode are alternately placed in a laminated mold provided with a groove for the electrode extraction piece and a groove for the auxiliary projection piece, and Multiple sheets are inserted and stacked so that the extraction piece protrudes to the opposite side every other layer, and after stacking, the auxiliary protruding piece of each metal electrode is removed by external force.
1. A method for manufacturing a laminated piezoelectric element, comprising connecting an electrode extraction piece to an external electrode to form a laminated piezoelectric element.