JP2001024245A - Electrode structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure which can prevent the peeling of a film-like electrode from a ceramic substrate though the electrode has a thin thickness, and can facilitate the soldering of the electrode to a piezoelectric/ electrostrictive element. SOLUTION: In an electrode structure, a film-like electrode composed of 96.5-99.98 vol.% platinum and 0.02-3.5 vol.% titania (Ti02) is provided on a ceramic substrate. It is preferable to make the ceramic substrate of zirconia. In addition, the structure can be the constituent member of an actuator or sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode structure used as a component of an actuator or a sensor.

[0002]

2. Description of the Related Art As shown in FIG. 1, an electrode structure 4 in which a film electrode 1 is provided on a ceramic substrate 5 has, for example, a piezoelectric / electrostrictive element 2 and another electrode 3 on the film electrode 1. Is used as a component of an actuator or a sensor. When used as a component of an actuator, the electrode structure can control the deformation and return of the piezoelectric / electrostrictive element with high accuracy by periodically turning on and off a certain electric field. On the other hand, when used as a component of a sensor, the electrode structure functions to transmit a displacement applied from the outside to the piezoelectric / electrostrictive element, and the piezoelectric / electrostrictive element deforms following the deformation of the electrode structure. As a result, an electric field is generated in the piezoelectric / electrostrictive element, and by detecting this, the magnitude of the displacement and the like are detected.

In such an electrode structure, since platinum, which is more expensive than conventional materials, is used as the material of the film-shaped electrode, in order to reduce the manufacturing cost of the electrode structure, the film-shaped electrode must be made of a conventional material. It is desirable to reduce the thickness from about 15 μm to about 2 to 5 μm. Further, making the film-shaped electrode thin also contributes to increasing the sensitivity of the actuator and the sensor.

[0004]

However, when the thickness of the film electrode is reduced, the electrode film becomes porous and the film electrode is easily peeled off from the ceramic substrate. When the film-shaped electrode is peeled off, there is a disadvantage that the sensitivity is poor when the electrode structure is used as a component of an actuator or a sensor. In particular, when the thickness of the film-shaped electrode is reduced, when the film of the piezoelectric / electrostrictive element is formed on the film-shaped electrode, the film-shaped electrode is easily peeled off from the ceramic substrate, and it is difficult to form an electrode structure. was there.

The present invention has been made in view of such circumstances, and an object of the present invention is to allow a film-like electrode to peel off from a ceramic substrate even though the thickness of the film-like electrode is smaller than before. It is to provide a difficult electrode structure.

[0006]

Means for Solving the Problems According to the present invention, there is provided an electrode structure comprising a ceramic substrate provided with a film electrode, wherein the film electrode comprises 96.5 to 99.98% by weight of platinum, titania (TiO ₂₎ electrode structure composed of 0.02 to 3.5 wt% is provided. In the above electrode structure, the ceramic substrate is preferably made of zirconia. Further, the above-mentioned electrode structure may be a constituent member of an actuator or a sensor.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The electrode structure of the present invention comprises a ceramic substrate provided with a film electrode, and the film electrode is made of platinum 9
6.5 to 99.98% by weight, titania (TiO ₂ ) 0.
It consists of 02 to 3.5% by weight.

[0008] The titania content in the membrane electrode is set to 0.02 to 3.5% by weight, as shown in FIG. 2 and Table 1 by containing titania in platinum within the above range. This is because the adhesive strength between the electrode and the ceramic substrate can be 1.5 kg / 2 mm or more, and the film electrode can be hardly peeled off from the ceramic substrate. When the content of titania is out of the above range, as shown in FIG. 2, the adhesive strength between the film electrode and the ceramic substrate is significantly reduced, so that the film electrode is easily peeled off and the titania is insulated. When the content is more than 3.5% by weight, the resistance of the film electrode is too large. More preferably, the content of titania in the film-like electrode is 0.05 to 2.4% by weight. Within this range, the adhesive strength between the film-shaped electrode and the ceramic substrate is 2.0 kg / 2 mm or more, so that peeling of the film-shaped electrode can be more reliably prevented.

[0009]

[Table 1]

Here, the term “adhesive strength” is a concept representing the adhesive force between a base material and a conductor, and is defined as a φ
It refers to a tensile strength when a lead wire obtained by bending a 0.6 mm tin-coated soft copper wire into an L shape is soldered and pulled vertically at a pulling speed of 20 mm / sec.

In the electrode structure of the present invention, for example, an oxide-based ceramic such as alumina or zirconia can be used as the material of the ceramic substrate. However, using zirconia is preferable from the viewpoint of high strength and high toughness. preferable.

In the electrode structure of the present invention, the thickness of the ceramic substrate is preferably 0.1 to 1 mm.

As described above, in the electrode structure of the present invention, since the adhesive strength between the membrane electrode and the ceramic substrate is large, even if the thickness of the membrane electrode is 2 to 5 μm, the membrane electrode peels off. It is possible to prevent the inconvenience of poor sensitivity due to peeling of the film electrode. Further, it is possible to manufacture an electrode structure having a film of a piezoelectric / electrostrictive element formed thereon without peeling off the film-like electrode.

The electrode structure of the present invention is manufactured by forming a film-shaped electrode on a ceramic substrate by various known film forming methods, for example, a thick film forming method such as screen printing or spraying, and performing firing. Is done.

Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to these, and various modifications may be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that changes, modifications, improvements, and the like can be made.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) On the surface of a zirconia substrate,
Consisting of 96.5% by weight of platinum and 3.5% by weight of titania;
An electrode structure was manufactured by providing a film-like electrode having a thickness of 3 μm, and the adhesive strength between the film-like electrode and the zirconia substrate and the specific resistance of the film-like electrode were examined.

The zirconia substrate is 50 mm long and 30 m wide
m and a thickness of 0.3 mm were used. The film-like electrode was provided by printing a thick paste of the electrode paste on the surface of the zirconia substrate, followed by firing. The composition of the electrode paste was 87% by weight of platinum powder, 3.2% by weight of titania, 9.8% by weight of an organic vehicle and a solvent. Also, firing is 1330
C. for 2 hours.

The adhesive strength between the film electrode and the zirconia substrate was measured by the method described above. Further, the specific resistance of the film electrode was measured. Table 1 shows the results.

Example 2 On the surface of a zirconia substrate,
Consisting of 97.6% by weight of platinum and 2.4% by weight of titania;
An electrode structure was manufactured in the same manner as in Example 1 by providing a film-like electrode having a thickness of 4 μm, and the adhesive strength between the film-like electrode and the zirconia substrate and the specific resistance of the film-like electrode were examined. The composition of the electrode paste was as follows: platinum powder 83% by weight, titania 2
% By weight, 15% by weight of organic vehicle and solvent. Table 1
Shows the results.

(Comparative Example 1) On the surface of a zirconia substrate,
Consisting of 96.0% by weight of platinum and 4.0% by weight of titania;
An electrode structure was manufactured in the same manner as in Example 1 by providing a film-shaped electrode having a thickness of 3 μm, and the adhesive strength between the film-shaped electrode and the zirconia substrate and the specific resistance of the film-shaped electrode were examined. The composition of the electrode paste was 86.6% by weight of platinum powder, 3.6% by weight of titania, 9.8% by weight of an organic vehicle and a solvent. Table 1 shows the results.

Comparative Example 2 On the surface of a zirconia substrate,
An electrode structure was manufactured in the same manner as in Example 1 by providing a film-shaped electrode made of platinum and having a thickness of 4 μm, and the adhesive strength between the film-shaped electrode and the zirconia substrate and the specific resistance of the film-shaped electrode were examined. The composition of the electrode paste was platinum powder 90.2
% By weight, and 9.8% by weight of the organic vehicle and the solvent. Table 1 shows the results.

[0023]

[Table 2]

From the comparison between the embodiment and the comparative example, by limiting the composition ratio of platinum and titania in the film electrode to a predetermined value, it is possible to increase the adhesive strength between the film electrode and the zirconia substrate, It can be seen that peeling of the film electrode can be prevented.

[0025]

EFFECTS OF THE INVENTION In the electrode structure of the present invention, even if the thickness of the film-like electrode is 2 to 5 μm, the film-like electrode is difficult to peel off, so that the problem of poor sensitivity due to the peel-off of the film-like electrode occurs. Can be prevented. Further, it is easy to form a film-like piezoelectric / electrostrictive element on the electrode without peeling off the film-like electrode.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an electrode structure.

FIG. 2 is a graph showing the relationship between the titania content of a film electrode and the adhesive strength.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Membrane electrode, 2 ... Piezoelectric / electrostrictive element, 3 ... Other electrode, 4
... electrode structure, 5 ... ceramic substrate.

Claims (3)

[Claims] 1. An electrode structure comprising a ceramic substrate and a film electrode provided thereon, wherein the film electrode comprises 96.5 to 99.98% by weight of platinum, and 0.02 to 3.5 of titania (TiO ₂ ). An electrode structure characterized by comprising by weight. 2. The electrode structure according to claim 1, wherein said ceramic substrate is made of zirconia. 3. The electrode structure according to claim 1, which is a constituent member of an actuator or a sensor.