JP2002257845A - Piezoelectric element for accelerometer and method of manufacturing the same, and grinding whetstone used for method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element for an accelerometer, in which disconnection is small, and to provide a method of manufacturing the piezoelectric element as well as to provide a grinding whetstone, used in the method of manufacturing the piezoelectric element. SOLUTION: A support 12 is installed at a free vibration part 11 so as to become nearly L-shaped. An inclined plane 13 is provided in a corner part in a region, in which the part 11 comes into contact with the support 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element for an acceleration sensor, a method of manufacturing the same, and a grinding wheel used in the method.

[0002]

2. Description of the Related Art A conventional piezoelectric element for an acceleration sensor is shown in FIG.
As shown in FIG. 1, a first electrode film 3 is provided on a surface in the longitudinal direction of a substantially L-shaped piezoelectric element provided with a support 2 on one surface of a free vibrating portion 1, and the first electrode film 3 The second electrode film 4 was provided on the surface of the piezoelectric element, that is, the bottom and side surfaces of the support 2 and the free vibration portion.

[0003]

When the second electrode film 4 is formed by a plating method, the free vibration portion 1 and the support 2
Since the region in contact with is sharp at a substantially right angle, it is difficult to form an electrode film at this sharp portion, and the second electrode film 4 is disconnected.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a piezoelectric element for an acceleration sensor with less disconnection and a method of manufacturing the same.

[0005]

To achieve the above object, the present invention has the following arrangement.

The first invention of the present invention has a curved surface or an inclined surface serving as a chamfered surface at a corner of a region where the free vibration portion and the support come into contact with each other, so that the mechanical strength is high and the reliability is high. Having.

According to a second aspect of the present invention, the support has a second inclined surface serving as a curved surface or a chamfered surface on both side surfaces away from the free vibration portion.

According to a third aspect of the present invention, in the step of forming the free vibration portion by grinding the groove, the corner portion of the area where the free vibration portion and the support come into contact with each other is formed so as to have a curved surface or a chamfered inclined surface. This has the effect of shortening the process time.

According to a fourth aspect of the present invention, the step of forming the inclined surface includes:
A second inclined surface is formed on a side surface of the support that is away from the free vibration portion.

According to a fifth aspect of the present invention, in the grinding wheel for grinding, a portion corresponding to a corner between the main surface of the support and at least one side thereof and a corner formed by the free vibration portion and one side of the main surface is provided. It has a surface.

According to a sixth aspect of the present invention, the grinding wheel is a fixed abrasive type grinding wheel comprising a metal-based binder and diamond as abrasive grains, and has an effect of reducing wear of the grinding wheel itself.

A seventh aspect of the present invention is a diamond abrasive having a particle diameter smaller than # 1000, and has an effect of reducing damage during processing.

According to an eighth aspect of the present invention, the grinding wheel is formed at a corner corresponding to a corner between the main surface of the support and at least one side thereof, and a corner formed by the free vibration portion and one side of the main surface. The formed shape is formed by electric discharge machining.

According to a ninth aspect, the curvature of a curved surface formed at a corner of a grinding wheel is at least three times the average particle diameter of the diamond abrasive grains in the grinding wheel. Has the effect of maintaining

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a piezoelectric element for an acceleration sensor according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a piezoelectric element for an acceleration sensor according to an embodiment of the present invention.

The piezoelectric element for an acceleration sensor according to the present embodiment includes a free vibrating portion 11 for detecting acceleration, and a support 12 formed on a side of the free vibrating portion 11 so as to be substantially L-shaped. It has a piezoelectric element. In this case, the piezoelectric element has an inclined surface 13 which is a chamfered surface that forms a curved surface or a corner in a region which is in contact with and surrounded by the free vibration portion 11 and the support 12 shown in FIG. Further, a second inclined surface 14 is provided as a chamfered surface that forms a curved surface or a corner in a region that is in contact with and is surrounded by the curved surface and the inner surface of the support 12 shown in FIG.

The support 1 which is one surface of the free vibration section 11
2 is provided with a first electrode film 15, and is provided at least from the other surface to the inner surface of the support 12, that is, from the other surface of the free vibrating portion 11 to the inner surface of the support 12 to the bottom surface. , A second electrode film 16.

These first and second electrode films 15 and 16 are
From the piezoelectric element side, any one of Cr, Ni, and Ti is superimposed on this first layer to form Cr / Au; Ni / A
u or Ti / Au is formed by electrolytic or electroless plating, vapor deposition, sputtering, or the like.

A method of manufacturing the acceleration sensor having the above-described configuration will be described below.

First, as shown in FIG. 2A, two piezoelectric single crystal rectangular plates are bonded and directly joined to form a piezoelectric single crystal rectangular plate 21.

Next, as shown in FIG. 2B, one of the piezoelectric single crystal rectangular plates 21 is ground to a predetermined thickness.

Next, as shown in FIG. 2 (c), groove grinding is performed on a predetermined position of the piezoelectric single crystal rectangular plate 21 using a grinding wheel 22 so that the free vibration section 11 shown in FIG. Support 1
2 are formed simultaneously. Grinding wheel 22 used in this step
As shown in FIG. 3, both sides are provided with a machining portion for chamfering a chamfer amount or a curvature, for example, as shown by a region (A) in FIG. Processing similar to the area indicated by the reference numeral (B) in FIG. 1 is performed on the grinding wheel 22. By transferring the shape of the grinding wheel 22 using the grinding wheel 22, the free vibration portion 11 and the support 12 are transferred.
And at the same time. The grinding wheel 22 uses diamond grains as abrasive grains and uses metal as a binder for the abrasive grains. Examples of the metal used for the binder include Fe-based and Al-based metals. The reason why the metal material is selected as the binder is that electric discharge machining can be used for shaping the grinding wheel 22. Since the shape accuracy of the grinding wheel 22 finally becomes the shape accuracy of the piezoelectric element for the acceleration sensor, it is necessary to process the side surface of the grinding wheel 22 with high accuracy. In addition, the average grinding particle diameter of the grinding wheel 22 is 3 by the amount of chamfering in the area shown by the reference numeral (B) in FIG.
By making it twice or more, the load on the grinding process of the abrasive grains located at the corners of the grinding wheel 22 can be reduced and the shape accuracy can be maintained. Therefore, since the frequency of replacing the grinding wheel 22 can be reduced, it is possible to manufacture the acceleration sensor piezoelectric element at low cost.

Next, as shown in FIG. 2E, first and second electrode films 15 and 16 are formed on the opposing surfaces of the rectangular plate, and are cut into a predetermined size. The piezoelectric element for the acceleration sensor is manufactured by singulation. In the case where at least the second electrode film 16 is formed, the region shown by the symbol (B) in FIG. 1 is formed as the inclined surface 13, so that the electrode film can be easily formed even by using the plating method, and a defect such as disconnection can be caused. Can be greatly reduced. Further, even when the sputtering method or the vapor deposition method is used, the directivity of the vapor deposition site can be reduced, so that the cost of the apparatus can be reduced.

Although the present embodiment has been described with reference to a substantially L-shaped cantilever type piezoelectric element for an acceleration sensor, as shown in FIG. Has the effect of

[0026]

As described above, the present invention has the effect of providing a low-cost, highly reliable piezoelectric element for an acceleration sensor without disconnection at a corner.

[Brief description of the drawings]

FIG. 1 is a perspective view of a piezoelectric element for an acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a view for explaining the manufacturing method.

FIG. 3 is a diagram illustrating a cross-sectional shape of a grinding wheel used in the manufacturing method.

FIG. 4 is a perspective view of a piezoelectric element for an acceleration sensor according to another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional acceleration sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Free vibration part 12 Support body 13 Inclined surface 14 2nd inclined surface 15 1st electrode film 16 2nd electrode film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 41/08 H01L 41/08 Z 41/22 41/22 Z (72) Inventor Motoyuki Taji Kyotanabe, Kyoto 55-12 Osumihama Matsushita Nitto Electric Co., Ltd. F-term (reference) 3C049 AA02 AA09 CA01 3C063 AA02 AB03 BA02 BA24 BB02 BC02 EE01 EE29 FF08 FF23

Claims (9)

[The claims] 1. A free vibration part and a support provided on at least one of the free vibration parts, and a curved surface or a chamfered surface is formed at a corner of a region where the free vibration part and the support come into contact with each other. Element for acceleration sensor provided. 2. A piezoelectric element for an acceleration sensor, wherein the support has a second inclined surface which is a curved surface or a chamfered surface on both side surfaces away from the free vibration portion. 3. A piezoelectric single crystal rectangular plate is subjected to groove grinding using a grinding wheel to form a free vibrating portion and a support, and electrodes are formed on opposing surfaces of the piezoelectric single crystal rectangular plate having the free vibrating portion. The step of forming a film and forming a free vibration portion by groove grinding is performed by forming an acceleration in which a corner of a region where the free vibration portion and the support come into contact with each other is formed into a curved surface or an inclined surface serving as a chamfered surface. A method for manufacturing a piezoelectric element for a sensor. 4. The method of manufacturing a piezoelectric element for an acceleration sensor according to claim 3, wherein the step of forming the inclined surface includes forming a second inclined surface on a side surface of the support that is away from the free vibration portion. 5. A grinding wheel for use in groove grinding, comprising: a corner between a main surface of a support and at least one side thereof;
4. The method for manufacturing a piezoelectric element for an acceleration sensor according to claim 3, wherein an inclined surface is provided at a portion corresponding to a corner formed by the free vibration portion and one side surface of the main surface. 6. The method for manufacturing a piezoelectric element for an acceleration sensor according to claim 5, wherein the grinding wheel is a fixed abrasive type grinding wheel comprising a metal-based binder and diamond as abrasive particles. 7. The method for manufacturing a piezoelectric element for an acceleration sensor according to claim 5, wherein the grinding wheel has a particle diameter of diamond abrasive grains smaller than # 1000. 8. The grinding wheel has a shape formed at a portion corresponding to a corner between the main surface of the support and at least one side thereof, and a corner formed by the free vibration portion and one side of the main surface. 6. The method according to claim 5, wherein the piezoelectric element is formed by electric discharge machining. 9. The grinding wheel according to claim 1, wherein the curvature of the curved surface formed at the corner is 3 times the average particle diameter of the diamond abrasive grains in the grinding wheel.
A grinding wheel for use in the method for manufacturing a piezoelectric element for an acceleration sensor according to claim 5, wherein the grinding wheel is at least twice as large.