JPH05126626A - Manufacture of piezoelectric vibration sensor - Google Patents

Abstract

PURPOSE:To reduce the dispersion of output between products by using film-like dielectric adhesives having no fluidity at the adhesive temperature on both faces of a piezoelectric body film, and integrally sticking metal thin plates to the piezoelectric body film. CONSTITUTION:Film-like dielectric adhesives 14 having no fluidity at the adhesive temperature are arranged on both faces of a piezoelectric body film 7, and metal thin plates 8 are stuck to it. PVDF or the like is used for the film 7, and acrylic resin, EVA, epoxy resin or the like are used for the adhesives 14. Support plates 10, 10 are integrally stuck on both faces of an integrated film-like piezoelectric body 9. A laminated sheet 15 thus obtained is died into a proper shape to obtain the detection section chip of a sensor. The sensor having little dispersion of output between products and abundant shock resistance can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a piezoelectric vibration sensor having excellent shock resistance, and more particularly to a method of manufacturing a piezoelectric vibration sensor for reducing variations in output between products.

[0002]

2. Description of the Related Art Regarding piezoelectric vibration sensors, we have already
We propose a piezoelectric vibration sensor that uses electric charges generated by compressing a polymeric piezoelectric film such as PVDF, has a simple structure, is strong against impact, has large anisotropy of sensitivity, and has a small pyroelectric output. Patent applications have been filed as Japanese Patent Application No. 1-113255, Japanese Patent Application No. 1-251405, and Japanese Patent Application No. 1-318277.

FIG. 2 exemplifies such a vibration sensor device. The vibration sensor device 1 includes a vibration sensor unit 4 including a piezoelectric vibration sensor 2 and a circuit board 3 having an impedance conversion circuit for converting the output from the piezoelectric vibration sensor into an impedance and an output amplification circuit. It is housed inside. The vibration sensor unit 4 is configured by mounting the piezoelectric vibration sensor 2 on one surface side of the circuit board 3 and disposing the circuit 6 on the other surface side.

As shown in FIG. 3, this piezoelectric type acceleration sensor 2 includes a thin metal plate 8 serving as an electrode such as a copper foil on both sides of a piezoelectric film 7 made of a polymer film such as PVDF.
On both sides of the film-shaped piezoelectric body 9 in which 8 are bonded and integrated, the support plates 10 and 10 made of a rigid body such as a glass epoxy plate are bonded and integrated to form a sensing part 11, and on the sensing part 11,
The load body 12 is placed and configured. This sensing unit 11
A dielectric adhesive such as an epoxy-based adhesive is used for adhesion between the inner layers. Reference numerals 13 and 14 in the figure show the adhesive layers.

Since this piezoelectric vibration sensor has such a structure, it can be miniaturized, is easy to manufacture, and has a conventional problem because a polymer film is used for the piezoelectric body. Piezoelectric body (previously ceramic piezoelectric body)
It has various advantages such as no damage of the piezoelectric body itself due to the brittleness of the piezoelectric body at the time of impact.

However, in such a sensor,
When a shock is applied from the lateral direction, peeling may occur between the piezoelectric film 7 forming the film piezoelectric body 9 and the metal thin plates 8 and 8 adhered to both surfaces thereof, and the sensor may be destroyed. Therefore, in order to solve this, when manufacturing the film-shaped piezoelectric body of the piezoelectric type vibration sensor, a dielectric adhesive is applied to both surfaces of the piezoelectric body film, and a metal thin plate is further applied to 0.5 to 5 k.
A manufacturing method of adhering and integrating while applying a pressure of g / cm ² is proposed, and a patent application is filed as Japanese Patent Application No. 3-84635.

[0007]

However, in the sensor manufactured by such a method, although the impact resistance is improved, the dielectric adhesive is used as an electric capacitance component that enters in series with the piezoelectric film. There is a drawback in that the thickness of this adhesive is a major factor in determining the output when the output is taken out as a voltage, which causes a large variation among products. Specifically, if the pressure is too high, the piezoelectric film made of a polymer material is distorted, and this distortion is fixed without being released, resulting in residual distortion. When an impact is applied, the residual strain triggers the damage. On the other hand, when the bonding is performed with an excessively low pressure, the bonding layer is cured while being thick, or the bonding layer thickness becomes uneven, and these phenomena are reflected in the form of variations in the sensor output. Further, if the fluidity of the adhesive is uneven, the output will vary. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a manufacturing method that minimizes variations in output between products due to uneven pressure distribution during pressure bonding in a piezoelectric vibration sensor and uneven fluidity of an adhesive. I am trying.

[0008]

The object of the present invention is to dispose a film-like dielectric adhesive, which has no fluidity at the bonding temperature, on both sides of a piezoelectric film when manufacturing a film-like piezoelectric body for a piezoelectric vibration sensor. This is solved by a manufacturing method in which a thin metal plate is bonded and integrated with a piezoelectric film using this.

The present invention will be described in detail below. FIG. 1 shows an example of a method of manufacturing the piezoelectric vibration sensor of the present invention. In this method, first, a piezoelectric film 7 and a metal thin plate 8 are prepared, and a film-like dielectric adhesive 14 having no fluidity at the bonding temperature is arranged on both surfaces of the piezoelectric film 7, as shown in FIG. Then, the metal thin plate 8 is attached. A piezoelectric polymer film such as a PVDF film is preferably used as the piezoelectric film 7. Moreover, as the metal thin plate 8, a copper foil, an aluminum foil or the like is usually used. The film-shaped dielectric adhesive 14 is made of an acrylic resin-based, EVA-based, epoxy-based, synthetic rubber-based adhesive or the like having a flow temperature higher than the bonding temperature, and has a uniform thickness and extremely small unevenness. Is preferably used.

Next, as shown in FIG. 1B, support plates 10 and 10 are formed on both surfaces of the film-shaped piezoelectric material 9 obtained by adhesion and integration.
Are bonded and integrated with an epoxy adhesive or the like. As the material of the support plate, a material having a large rigidity, particularly a glass epoxy plate material, is preferably used.

Next, the obtained laminated plate 15 is cut into an appropriate shape by using a cutting machine such as a dicing saw to obtain a chip which becomes the sensing portion 11 of the sensor. In this cutting, the planar shape of the film-shaped piezoelectric body 9 is cut into a point-symmetrical shape with the sensing axis as the center of symmetry on a plane parallel to the measurement surface on which the sensor is mounted. The cut chip is adhered and fixed onto the circuit board 3, and the load body 1 is attached to the upper side of the chip.
2 is bonded and fixed with an epoxy adhesive or the like.

The load body 12 has a plane shape of a plane in contact with the sensing portion 11 which is point-symmetrical with the sensing axis as a center of symmetry, and has a cross section of an infinite number of planes passing through the sensing axis and perpendicular to the measuring surface. At this time, all the cross sections have a line-symmetrical shape with the sensing axis as the axis of symmetry, and the material thereof is not particularly limited, but a metal material such as brass is preferably used.

In this way, it is possible to manufacture a piezoelectric vibration sensor having a very small variation in output among products, a simple structure, and excellent impact resistance. Further, since it is not necessary to use a pressing device, workability can be improved, and production efficiency is higher than when a liquid adhesive is used only by waiting for the solidification time of the liquid adhesive.

[0014]

【Example】

(Example 1) A PVDF film having a thickness of 100 μm was coated with 3c.
Cut into m × 3 cm square shape, and place synthetic rubber film adhesive (flowing temperature 100 ° C.) of the same shape (3 cm × 3 cm square shape) and thickness of 50 μm on both sides.
A 30 μm-thick copper foil having the same shape (3 cm × 3 cm square) was adhered to both surfaces of this at 80 ° C. Thereafter, a glass epoxy plate having a thickness of 1.5 mm and a size of 3 cm × 3 cm was adhered to the both surfaces with an epoxy adhesive. The laminated plate integrally bonded was cut into a size of 5 mm × 5 mm with a dicing saw. (Example 2) The film adhesive of Example 1 was replaced with an EVA film adhesive having a thickness of 50 μm (flowing temperature 90
A sensor was manufactured in the same manner except that the temperature was changed to ° C).

Comparative Example 1 A PVDF film having a thickness of 100 μm was cut into a 3 cm × 3 cm square shape, and epoxy adhesive was applied to both surfaces of the PVDF film, and the same shape (3 cm × 3 cm square shape) was applied to both surfaces. 30 μm thick copper foil of 1) was placed and pressed at a pressure of 0.5 to ⁵ kg / cm ² to be integrated. After that, the sensing unit was manufactured in the same manner as in Example 1. (Comparative Example 2) The film adhesive of Example 1 was replaced by a synthetic rubber film adhesive having a thickness of 50 μm (flowing temperature 8
A sensor was manufactured in the same manner except that the temperature was 0 ° C. (Comparative Example 3) The film adhesive in Example 1 was replaced with an EVA film adhesive having a thickness of 50 μm (flowing temperature 70
A sensor was manufactured in the same manner except that the temperature was changed to ° C).

Twenty sensing units were prepared for each of the piezoelectric vibration sensors manufactured by the above manufacturing method, 0.8 g of a brass weight was bonded to one side of the sensing unit with an epoxy adhesive, and the other side was bonded to the sensing unit. A piezoelectric vibration sensor was manufactured by adhering to an aluminum block. And 1G for each,
The variation was evaluated by measuring the output at the time of exciting at 80 Hz. The results of these tests are shown in Table 1. The variation of the output in Table 1 was 20 obtained in each Example and Comparative Example.
The output value of each sensor is averaged, and the average value is represented by the number of output sensors that are within ± 10% of the average value.

Margin below

[Table 1]

As is clear from Table 1, when the piezoelectric film and the thin metal plate were bonded and integrated, a film-like dielectric adhesive having no fluidity at the bonding temperature was used in Example 1,
No. 2 has little variation between products, and an accurate sensor can be manufactured with high yield.

[0019]

According to the method of manufacturing the piezoelectric vibration sensor of the present invention, when the film-shaped piezoelectric body is manufactured, the film-shaped dielectric adhesive having no fluidity at the bonding temperature is arranged on both surfaces of the piezoelectric film. Since the thin metal plates are bonded and integrated,
It is possible to manufacture a piezoelectric vibration sensor that has an extremely low variation in output between products and is excellent in impact resistance. Further, since it is not necessary to use a pressing device, workability can be improved, and a waiting time required for solidification of the liquid adhesive is not required, so that production efficiency can be improved.

[Brief description of drawings]

1A and 1B are views showing an example of a method for manufacturing a piezoelectric vibration sensor of the present invention, in which FIG. 1A is a side view showing a temporarily bonded state of a piezoelectric film and a thin metal plate, and FIG. 1B is a side view of a laminated plate. is there.

FIG. 2 is a side sectional view showing an example of a conventional piezoelectric vibration sensor.

FIG. 3 is an enlarged cross-sectional view of a main part of a conventional vibration sensor device.

[Explanation of reference numerals] 2 ... Piezoelectric vibration sensor, 3 ... Circuit board (base), 7 ... Piezoelectric film, 8 ... Metal thin plate, 9 ... Membrane piezoelectric material, 13 ...
Adhesive layer, 14 ... Film adhesive, 15 ... Laminated plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Imai 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd.

Claims (1)

[Claims] 1. When manufacturing a piezoelectric vibration sensor including a film-shaped piezoelectric body in which thin metal plates to be electrodes are bonded and integrated on both surfaces of a piezoelectric film, fluidity is maintained on both surfaces of the piezoelectric film at the bonding temperature. A method for manufacturing a piezoelectric vibration sensor, comprising disposing a film-like dielectric adhesive, and using the same to integrally bond a thin metal plate to a piezoelectric film.