JPH11127053A - Piezoelectric vibrating element and angular velocity sensor piezoelectric vibrating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator that has an electrode configuration excellent with a bonding strength with a lead wire connected by an ultrasonic wave wire bonding WB and to provide a piezoelectric vibrating element using it. SOLUTION: An angular velocity sensor being a piezoelectric vibrating element is provided with a vibrating member 1 made of a piezoelectric material, a vibrator A1 made up of electrodes formed in the vibrating member 1 and a board 2 that supports and fixes the vibrating body A1, and electrodes 10-17 on an X1 plane of the vibrating member 1 connect to lead terminals P of the board 2 by lead wires S mainly made of aluminum by the ultrasonic wave wire bonding method. The electrodes 10-17 has a 2-layer structure having WB electrodes 110-117 at the side connecting to the lead wires S at the connection part with the lead wires S. The electrodes 10-17 and 110-117 are formed by a silver thick film having palladium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating body made of a piezoelectric body, and more particularly, to a piezoelectric vibrating body having an electrode electrically connected to a bonding wire and a piezoelectric vibrating element using the same. And an angular velocity sensor.

[0002]

2. Description of the Related Art Conventionally, as a piezoelectric vibrating element of this kind,
For example, as described in Japanese Patent Application Laid-Open No. 8-210860, an angular velocity sensor using a tuning-fork type piezoelectric vibrator has been proposed. The configuration is shown in FIG. 13 and FIG. The piezoelectric vibrator A includes a vibrating member 1 made of a piezoelectric material and electrodes formed on each side surface of the vibrating member 1. The vibration member 1 includes a pair of quadrangular prism-shaped arm portions (vibration portions) 4,
5 and a connecting portion 6 connecting both ends of the arm portions 4 and 5 form a tuning fork shape. And the vibrating body A is
It is connected and fixed to the substrate 2 via the support 3.

In the vibrating member 1, the drive electrode 1 is provided on the X1 surface of the opposing side surfaces X1 and X2 having a substantially U-shape.
0 and 11, reference electrodes 12 and the like are arranged, and side electrodes (detection electrodes) 18 and 19 for detecting angular velocity are arranged on Y1 and Y2 planes, which are side faces orthogonal to the X1 and X2 planes.
A common electrode 20 serving as a reference potential electrode for the electrodes on the X1 plane and the side electrodes 18 and 19 is formed on the entire surface of the X2 plane facing the X2 plane.
Are arranged on the entire surface.

The operating principle of this angular velocity sensor is as follows. That is, the arm portions 4 and 5 extend in the y-axis direction orthogonal to the z-axis parallel to the longitudinal direction of the rectangular pillar-shaped arm portions 4 and 5.
And oscillate by driving. Then, flexural vibration of the arms 4 and 5 generated in the x-axis direction orthogonal to the z-axis and the y-axis is detected by Coriolis force generated when a rotational angular velocity is input to the vibrating arms 4 and 5. Vibration is detected electrically and the magnitude of angular velocity is determined.

[0005]

In the above angular velocity sensor, each electrode on the vibration member 1 is
Are connected by a wire bonding method (hereinafter abbreviated as WB). Normal W
B has higher productivity than soldering, whereby each electrode on the vibration member 1 is connected to an external circuit via a connection terminal.

However, in the past, a specific method for WB has not been studied in a piezoelectric vibration element represented by the above-mentioned angular velocity sensor. Accordingly, the present applicant has previously made a proposal on WB based on the above-mentioned angular velocity sensor in Japanese Patent Application No. 9-156932. The proposal in this prior application is based on the study of WB from the viewpoint of the material of the lead wire. In the piezoelectric vibrator, the electrode on the vibrating member and the connection terminal on the substrate are connected to the ultrasonic WB of the lead wire mainly composed of aluminum. Are connected by. Thereby,
Since bonding can be performed without heating, polarization deterioration due to heat of the piezoelectric body forming the vibration member can be prevented at the connection portion between the electrode and the lead wire, and excellent sensor performance (temperature drift and the like) can be realized.

In the above prior application, the temperature drift is reduced by reducing unnecessary vibration generated by the lead wire when the piezoelectric vibrator vibrates, and the load applied to the vibrating member via the lead wire during bonding is reduced. In order to prevent the vibrating member from being broken by making it smaller, the diameter of the lead wire is set to, for example, a fine wire of 50 μm or less. However, when such a thin wire is used, the connection area with the electrode is reduced. Therefore, in order to improve the reliability of the piezoelectric vibrating element, the ultrasonic wave W
In the bonding by B, it is necessary to consider the electrode surface and to further improve the bonding strength.

The present invention has been made in view of this problem, and provides a piezoelectric vibrating body having an electrode configuration excellent in bonding strength to a lead wire connected by ultrasonic WB, and a piezoelectric vibrating element using the same. The purpose is to do.

[0009]

As a result of an experimental study of various electrode materials, it has been found that an electrode having excellent bonding strength can be realized with a predetermined material. That is, according to the first to ninth aspects of the present invention, the vibrating member (1, 101, 201) made of a piezoelectric body and the electrodes (10 to 17, 110 to 117, 12) formed on the vibrating member are provided.
0 to 123, 150 to 153, 207 to 212, 257
262) and a connection terminal (P) for inputting / outputting a signal to / from the vibrating member via the electrode, wherein the electrode and the connection terminal are composed of a lead wire (S) mainly composed of aluminum. And the electrode is formed of a thick silver film containing palladium.

Here, the silver thick film containing palladium means a thick film containing two components of silver (Ag) and palladium (Pd). Thereby, the bonding strength between the lead wire and the electrode in bonding by ultrasonic WB is improved, and a piezoelectric vibration element excellent in reliability and durability can be provided. Also, in the invention of claim 4, the electrodes (10 to 17, 110 to 117, 120 to
123, 150-153, 207-212, 257-2
62) wherein the total film thickness is 5 μm or more and 40 μm or less.

When the film thickness is smaller than 5 μm, the thick film is broken by the ultrasonic power at the time of the ultrasonic wave WB, and the strength of the joint is deteriorated. On the other hand, when the film thickness is greater than 40 μm, during printing and firing of a thick film, when drying and firing, the stress tends to be uneven inside the film, and cracks and the like are likely to occur on the electrode surface. In addition, the electrode is likely to undulate, causing a decrease in surface roughness. According to the present invention, these problems can be prevented, and the joining strength can be further improved.

In the case of a two-layer structure as in the invention of claim 4, since each layer can be constituted independently, the vibration members (1,
101, 201) The bonding property with each of the main body and the lead wire (S) can be optimized, and the bonding strength can be further improved.
Here, in the two-layer structure according to claim 4, the second electrode (110 to 11) on the side to which the lead wire (S) is connected.
7, 150 to 153, 257 to 262), the weight ratio of palladium to silver was studied, and as a result of the invention described in claims 5 and 6, the amount of palladium contained in the second electrode was reduced. It was found that when the content was 5% by weight or more based on the total amount of palladium and silver, the bonding strength between the lead wire and the second electrode could be made higher.

The silver (A) containing palladium (Pd)
g) When a thick film is formed on a piezoelectric body, Ag-Pd is usually used.
The conductor paste is screen-printed on the piezoelectric body and formed by firing and curing. Here, the melting point of palladium (about 155)
5 [deg.] C.) is higher than silver (about 960 [deg.] C.), so if too much, the second electrodes (110 to 117, 150 to 15).
3, 257 to 262) are deteriorated. In addition to this effect on sinterability, palladium is expensive, so the upper limit of the palladium content is preferably 50% by weight for practical use.

[0014] Further, as described in claim 7, claim 4
The first electrodes (10 to 17, 120 to 123,
207 to 212), when the content of glass or an inorganic oxide (hereinafter, referred to as glass) is 1% by weight or more and 30% by weight or less with respect to the total amount, the adhesion between the piezoelectric body and the electrode is improved. Thus, the bonding strength of the entire electrode can be further improved.

Here, glass or the like is mixed as a powder into the Ag-Pd conductor paste and melted during firing to improve the adhesion between the piezoelectric body and the electrode conductor. However, if the content of glass or the like is too large, the piezoelectric body will be deformed during firing. In addition, since the bonding between the lead wire (S) and the electrode by the ultrasonic WB is achieved by bonding between metal atoms,
The presence of inorganic molecules such as glass hinders bonding. Therefore, in the invention according to claim 8, the second electrode (110 to 117, 150 to 15) on the side to which the lead wire is connected is provided.
3, 257 to 262) containing almost no glass or the like (1
(Less than 0% by weight, preferably 0% by weight) to improve the adhesion between the lead wire and the electrode.

Incidentally, the lead wire (S) in each of the first to eighth aspects of the present invention is preferably such that 90% by weight or more is made of aluminum as in the ninth aspect of the present invention. The invention according to claims 10 to 13 is one in which the piezoelectric vibration element is an angular velocity sensor. The present invention also provides each electrode (10, 11, 14 to 17, 110, 111, 11) on the vibration member (1, 101, 201).
4-117, 120, 122, 123, 150, 15
2,153,207,209-212,257,259
To 262) are silver thick films containing palladium, and an angular velocity sensor having a bonding strength improving effect equivalent to that of the first aspect of the present invention can be obtained.

According to the eleventh and twelfth aspects of the invention, an angular velocity sensor having the same effect of improving the bonding strength as the piezoelectric element according to the fifth and sixth aspects can be obtained. According to the fourteenth aspect of the present invention, the vibration member (1, 101, 201) made of a piezoelectric body and the electrodes (10-17, 110-11) formed on the vibration member are provided.
7, 120-123, 150-153, 207-21
2, 257 to 262),
This electrode is to be electrically connected to a lead wire (S) mainly composed of aluminum by an ultrasonic wire bonding method, and is formed of a silver thick film containing palladium. It is characterized by.

As a result, a piezoelectric vibrating body having the same effect of improving the bonding strength as that of the first aspect can be obtained. Further, electrodes (10 to 17, 110 to 117, 120 to 123, 15) formed of a silver thick film containing palladium.
0-153, 207-212, 257-262), as a result of further study, show that when the environment surrounding the joint between the electrode and the lead wire (S) is a specific environment, good joint strength is exhibited. Was found.

That is, according to the sixteenth aspect of the present invention, the vibrating member (1, 101, 201) made of a piezoelectric body
And the electrodes (10 to 17, 11
0 to 117, 120 to 123, 150 to 153, 207
To 212, 257 to 262).
1, A2, A3), wherein the electrode is formed of a thick silver film containing palladium, and is electrically connected to a lead wire (S) mainly composed of aluminum by an ultrasonic wire bonding method; At least the electrode is exposed to a nitrogen atmosphere.

As a result, the junction between the electrode and the lead wire is in a nitrogen atmosphere. In such a nitrogen atmosphere, a diffusion layer (alloy layer) of silver-palladium-aluminum is formed at the bonding interface at a high temperature. This diffusion layer maintains the bondability between the lead composed mainly of aluminum and the electrode composed of a thick silver film containing palladium, and does not deteriorate the bonding strength of the electrode.

Therefore, according to the present invention, while having the same effect of improving the bonding strength as in the first aspect of the present invention, the effect of the high-bonding diffusion layer in a nitrogen atmosphere provides
A more reliable piezoelectric vibration element can be provided. Furthermore, if the piezoelectric vibrating body (A1, A2, A3) is exposed to a nitrogen atmosphere, the electrodes (10 to 17, 110 to 117, 1) can be used.
20-123, 150-153, 207-212, 25
7 to 262), since the entire piezoelectric vibrating body is in a nitrogen atmosphere, the effect of the high-bonding diffusion layer in the nitrogen atmosphere can be more stably achieved.

Also, in each of the tenth to seventeenth aspects of the present invention, it is preferable that 90% by weight or more of the lead wire (S) is made of aluminum as in the ninth aspect of the present invention. Also, in the piezoelectric vibrating elements according to the sixteenth and seventeenth aspects, the lead wires (S) can be connected by an ultrasonic wire bonding method. In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means of embodiment mentioned later.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. (First Embodiment) In the present embodiment, an example in which the piezoelectric vibration element of the present invention is applied as a piezoelectric vibration type angular velocity sensor will be described. This angular velocity sensor is used as an angular velocity sensor used for, for example, prevention of camera shake of a video, navigation system, and vehicle attitude control of an automobile.

FIG. 1 is a perspective view showing the structure of the angular velocity sensor according to the present embodiment. The angular velocity sensor supports a vibrating body (piezoelectric vibrating body) A1 including a vibrating member 1 made of a piezoelectric body (PZT in the present embodiment) and electrodes formed on the vibrating member 1, and supports the vibrating body A1. A substrate 2 to be fixed is provided, and an electrode formed on the vibration member 1 and a lead terminal (connection terminal) P of the substrate 2 are electrically connected by a lead wire S.

The vibrating member 1 has a tuning fork shape comprising a pair of quadrangular prism-shaped arms (vibrating portions) 4 and 5 and a connecting portion 6 connecting one end of both arms 4 and 5. Further, a substantially E-shaped support portion 3 made of, for example, 42 alloy is joined to the connecting portion 6 with an epoxy adhesive. And the vibrating body A1 is welded and fixed to the substrate 2 via the support portion 3,
Due to the concave portion 2 a formed in the substrate 2, the vibrating body A 1 itself has a shape floating in parallel with the substrate 2.

Here, in the vibrating member 1, each side surface extending in the z-axis direction which is parallel to the longitudinal direction of both arms 4 and 5 and located at the center of both arms 4 and 5 is defined as follows. Of the X1 and X2 surfaces, which are a pair of substantially U-shaped surfaces that oppose each other, and the arm portions 4 and 5 and the connecting portion 6 form the same plane, the surface opposite to the substrate 2 is defined as the X1 surface (first surface). Side),
The other surface facing the X1 surface is defined as an X2 surface (second side surface). Further, it is located on the outer periphery of the vibrating member 1 and has
Of the Y1 and Y2 planes orthogonal to the y-axis, which is the arrangement direction, the arm section 4 side is the Y1 plane and the arm section 5 side is the Y2 plane.

The direction substantially orthogonal to the X1 plane and the X2 plane is defined as the x-axis, and the y-axis and the z-axis are shown in FIG.
The xyz orthogonal coordinate system shown in FIG. Hereinafter, the present embodiment will be described using the xyz rectangular coordinates. Hereinafter, the x-axis direction means a direction parallel to the x-axis. The same applies to the y-axis and z-axis directions.

Next, the configuration of the electrodes formed on the vibration member 1 will be described. FIG. 2 is a development view of the configuration of each electrode formed on the outer peripheral surface of the vibration member 1 as seen from the front, rear, left and right sides of the vibration member 1. (A) is the X1 plane, (b) is the X2 plane,
(C) shows an electrode configuration on the Y1 plane, and (d) shows an electrode configuration on the Y2 plane. On the X1 surface of the arm portions 4 and 5, drive electrodes 10, 11, reference electrodes 12, 13, extraction electrodes 14, 15, and pad electrodes 16, 17 are arranged in this order from the connection portion 6 side.
Each is formed by a conductive film.

Drive electrode 10 for driving vibration member 1
And 11 are located on the Y1 and Y2 surfaces of the arms 4 and 5 and the opposing surfaces of the arms 4 and 5 facing each other through the connecting portion 6. The reference electrodes 12 and 13 for feedback for monitoring the driving state and causing self-excited oscillation are located substantially at the center of the facing surfaces of the arms 4 and 5, respectively.

The pad electrodes 16 and 17 for outputting the angular velocity detection signal are located at the tips of the arms 4 and 5, respectively. In addition, extraction electrodes 14 and 15 that are electrically connected to a common electrode 20 described later are formed between the reference electrodes 12 and 13 and the pad electrodes 16 and 17. In addition, each electrode 10 on the X1 plane described above
Reference numeral 17 denotes a two-layer structure having wire bonding (hereinafter referred to as WB) electrodes 110 to 117 in a portion of the surface where the lead wires S are connected. That is, in the x-axis direction shown in FIG. 1, the WB electrodes 110 to 117 on the side to which the lead wire S is connected are connected to the second electrodes 10 to 17 on the vibrating member 1 body side, which are the first electrodes. (See FIG. 3). The configuration of the two-layer structure portion having the WB electrodes 110 to 117 in the electrodes 10 to 17 on the X1 plane will be described later in further detail.

On the Y1 and Y2 surfaces of the arms 4 and 5, detection electrodes (side electrodes) 18 and 19 for detecting detection vibration generated by Coriolis force when an angular velocity is generated are biased toward the X2 surface, respectively. It is formed in the position where it was. These detection electrodes 18 and 19 are respectively connected to the first connection electrode 2.
The pads 1 and 22 are electrically connected to the pad electrodes 16 and 17.

On the other hand, the drive electrodes 10 and 11, the reference electrodes 12 and 13,
A common electrode 20, which is a reference potential electrode for the detection electrodes 6 and 17, and the detection electrodes 18 and 19, is formed on almost the entire surface. The common electrode 20 is connected to the second connection electrodes 2 on the Y1 and Y2 planes.
The electrodes 3 and 24 are electrically connected to the extraction electrodes 14 and 15.

Each of the above electrodes 10 to 24 and 110 to 1
17 is silver (Ag) containing conductive palladium (Pd)
It is formed by a thick film. Further, as shown by a white arrow in FIG. 1, the vibration member 1 is polarized (although the directions may be reversed) in the x-axis direction substantially orthogonal to the X1 and X2 planes. Then, as shown in FIG. 3, each of the drive electrodes 10, 11, the reference electrodes 12, 13, the extraction electrodes 14, 15 and the pad electrodes 16, 17 on the X1 plane is
Each is electrically connected to the conductive lead wire S via the above-mentioned WB electrodes 110 to 117.

These lead wires S are further connected to the vibration member 1
Are connected to the respective lead terminals P provided on the surface K1 of the substrate 2 facing the X2 surface of each of the electrodes 10 to 17 and 1
10 to 117 are electrically connected to the lead terminals P.
These lead wires S have a wire diameter of 30 μm whose main component is made of Al (in this example, 90% by weight or more is made of aluminum).
m, and the connection is made by ultrasonic WB.

As shown in FIG. 1, a plurality of lead terminals P (for example, four on each side) are provided on both sides of the vibrating body A1.
And protrudes from a surface of the substrate 2 opposite to the vibrating body A1. An insulating glass 2a is arranged on the outer periphery of each lead terminal P, and plays a role of maintaining electrical insulation between the lead terminal P and the substrate 2. The lead terminal P is electrically connected to a drive / detection circuit (not shown) provided as an external circuit on the surface of the substrate 2 opposite to the vibrating body A1. Therefore, signals from the drive / detection circuit are input and output from the lead terminal P to the vibration member 1 via the electrodes 10 to 17 and 110 to 117.

The drive / detection circuit generates a drive signal (AC voltage) to the vibrating member 1 to drive and vibrate the arms 4 and 5 of the vibrating member 1 at a predetermined driving frequency. It is configured to perform detection processing such as synchronous detection of an electric signal generated from a vibration state at a driving frequency, and to detect an angular velocity Ωz around the z-axis (see FIG. 1) generated by the angular velocity sensor.

The vibrating body A1 is covered by a shell (lid) (not shown) adhered to the outer periphery of the substrate 2, and the vibrating body A1 is protected from the outside by the shell and the insulating glass (hermetic seal) 2a. And airtight.
As described above, the vibrating body A1 is assembled on the substrate 2 and is provided with electrical wiring, and is configured as an angular velocity sensor.

A mounting portion (not shown) for mounting the angular velocity sensor at an appropriate position on an object to be measured (vehicle or the like) is formed on the substrate 2, and the mounting portion is fastened and adhered via a vibration-proof rubber. It is attached to the object to be measured. The angular velocity sensor according to the present embodiment is mounted with the z-axis direction shown in FIG. The operation of the angular velocity sensor according to the present embodiment based on the above configuration will be described.

By applying alternating voltages (driving voltages) having phases different by 180 degrees in the x-axis direction between the common electrode 20 and the driving electrodes 10 and 11 via the extraction electrodes 14 and 15, Each of the arms 4 and 5 is driven and vibrated in the y-axis direction. At this time, an output current flowing between the reference electrodes 12 and 13 and the common electrode 20 is detected, and feedback is performed while monitoring a vibration state. As a result, even when the ambient temperature changes, the self-excited oscillation control can be performed so that the amplitude (drive amplitude) of the arm portions 4 and 5 in the y-axis direction becomes constant.

When the angular velocity Ωz is input to the vibrating body A1 around the z-axis (detection axis) at the center position of each of the arms 4 and 5 at the time of the above-mentioned driving vibration, the arms 4 and 5 are so-called Coriolis forces. 5 generates a flexural vibration and generates a detection vibration proportional to the angular velocity Ωz in the x-axis direction. An output current (detection signal) generated between the detection electrodes 18 and 19 and the common electrode 20 by the detection vibration is detected via the first connection electrodes 21 and 22 and the pad electrodes 16 and 17 and a voltage is detected. The angular velocity Ωz is detected by converting the value into a value.

Next, the electrodes 10 to 17 on the X1 plane are used.
Before describing the details of the electrode configurations of and 110-117,
The basis and wire diameter of the lead wire S as a wire whose main component is aluminum (Al) (hereinafter abbreviated as aluminum wire) is φ
The grounds for 30 μm will be described. Conventionally,
Gold (Au) wire is used for WB, and in this case, heating of the WB body (200 to 300 ° C.) is required. Since the WB is performed after the polarization processing, the PZT ceramics is degraded in polarization at such a high temperature, and the piezoelectric characteristics are degraded. As a result, the characteristics of the angular velocity sensor deteriorate. Therefore, the ultrasonic WB method of the aluminum wire which does not require heating is adopted.

Further, in the ultrasonic WB method, bonding is performed by applying a load (approximately 30 gf when the wire diameter is 30 μm) to the wire. Further, as described above, the vibration member 1 formed of PZT ceramics is bonded to the support portion 3 formed of 42 alloy with an epoxy adhesive, and the vibration member 1
The support portion 3 is fixed to the substrate 2 by welding so that the substrate floats.

That is, a material having relatively low strength such as PZT ceramics is also cantilevered with respect to the substrate 2 by a material having low strength such as epoxy adhesive. To perform WB in such a configuration, WB
If the load applied sometimes is excessive, the vibration member 1 itself or the above-mentioned bonded portion is broken. The larger the diameter of the aluminum wire, the greater the load.

If the diameter of the aluminum wire is large, the vibration state of the vibration member 1 is affected, for example, the vibration member 1 is hardly vibrated. As a result, the performance of the angular velocity sensor is deteriorated, such as an increase in temperature drift. . As an angular velocity sensor such as a vehicle behavior control system that requires high performance, the temperature drift is
It is preferable that the temperature is 10 ° / sec or less (at −40 ° C. to 85 ° C.). However, as a result of examining the relationship between various wire diameters of the lead wires and the temperature drift performance, in order to realize the above temperature drift performance, , The diameter of the lead wire is φ50μm or less,
It turned out to be desirable. However, due to the workability of the lead wire itself, it is not possible to make the diameter infinitely small, and in practice, it is 30 μm.
A degree or more is appropriate.

As described above, in this embodiment,
The lead wire S is connected to the ultrasonic WB in order to eliminate problems such as deterioration of piezoelectric characteristics due to heating during WB, increase of WB load due to excessive wire diameter, and adverse effect on temperature drift performance.
According to the method, the wire diameter is φ50 μm or less (φ30 μm in this example)
Is formed using an aluminum wire. Next, X
The details of the configuration of the two-layer structure portion of the electrodes 10 to 17 on one surface will be described. The configuration described below is the connection with the above-described thin aluminum wire having a wire diameter of φ30 μm and the piezoelectric vibration member 1 as the vibration member 1. It has been studied in view of the constraint of formation on the top. As described above, in the two-layer structure of the electrodes 10 to 17, the electrodes 10 to 17 on the vibration member 1 side are used as the first electrodes, and the WB electrodes 110 to 117 on the side to which the lead wires S are connected are used. This will be described as a second electrode.

As described above, the wire diameter of the WB of the piezoelectric vibration member cannot be increased. That is, the area of the joint cannot be increased. Even under such restrictions, a sufficient bonding strength can be obtained by using a silver thick film containing Pd (Ag-Pd thick film) in the present electrode configuration. This is because the present electrode configuration has the following requirements.

The surface roughness of the surface of the Ag-Pd thick film is small. The second electrode to be joined to the lead wire S contains almost no glass or an inorganic oxide (less than 1% by weight) that may hinder the joining. Ag-A that proceeds in a high temperature environment
The addition of Pd suppresses the diffusion between l and suppresses the deterioration of the bonding strength. Requirements are, for example,
By setting the average particle size of the silver powder to 0.1 to 2 μm and coating the surface of the silver powder with Pd, A
This is achieved by suppressing the grain growth of g. In the present embodiment, Rz (average surface roughness) is set to 3 μm or less as a preferable surface roughness for fine lines having a diameter of 50 μm or less, and the connection surface is smoothed.

The requirements will be described. When a thick silver film containing Pd is formed on a piezoelectric body, an Ag-Pd conductor paste is usually screen-printed on the piezoelectric body and formed by firing and curing. Glass or an inorganic oxide (hereinafter, referred to as glass or the like) is mixed as a powder into an Ag-Pd conductor paste and melts during firing to improve the adhesion between the piezoelectric body and the electrode conductor. However, if the content of glass or the like is too large, the piezoelectric body will be deformed during firing. In addition, since the bonding between the lead wire S and the electrode by the ultrasonic WB is achieved by bonding between metal atoms, the presence of inorganic molecules such as glass hinders the bonding.

Therefore, in this embodiment, the first electrode uses a glass-containing Ag-Pd thick film, and the second electrode uses a glass-less (less than 1% by weight) Ag-Pd thick film. Here, it is preferable that the second electrode has 0% by weight of glass that is an obstacle to bonding with the lead wire S. The amount of glass of the first electrode is 1 to 30% by weight. If the amount of glass is large, the vibrating member 1 warps when printing the thick film. As a result, the vibration member 1 does not vibrate correctly in the predetermined driving direction (the y-axis direction in the present embodiment), and as a result, unnecessary noise is generated. Therefore, it is desirable that the glass amount is small. However, if the glass does not contain 1% or more, the bonding strength between the PZT ceramics and the thick film itself cannot be ensured. Therefore, the range of 1 to 30% is desirable.
Note that the glass may be an inorganic oxide.

The total film thickness of the wire bonding portion of the two-layer structure needs to be 5 μm or more. If it is thinner than this, the ultrasonic wave power at the time of ultrasonic WB will break the thick film, and the strength of the joint will be degraded. Further, the total film thickness needs to be 40 μm or less. Above this, during printing and baking of a thick film, when drying and baking, the stress tends to be non-uniform inside the film, and cracks and the like are likely to occur on the electrode surface.
In addition, the electrode is likely to undulate, causing a decrease in surface roughness.

According to the present embodiment, the thickness of each layer of the first electrode and the second electrode is set to 2.5 μm to 20 μm, and the total thickness is set to 5 μm to 40 μm. Suppressed, prevents the destruction of the thick film due to the ultrasonic power during the ultrasonic WB, prevents the occurrence of cracks on the electrode surface during printing and firing of the thick film, and has a good surface roughness (Rz of 3 μm).
m or less).

Next, a description will be given of the results obtained by conducting an endurance experiment and examining the bonding reliability of the lead wire S in this embodiment. The experiment was performed using the configuration of the present embodiment in the electrode configuration of each electrode (first electrode) 10 to 17 and the WB electrode (second electrode) 110 to 117 on the X1 plane. Ag / Pd (weight ratio) = 98 /
2, 95/5, 92/8, 90/10, 80/20, 7
A 0/30 Ag / Pd conductor (the above examples) and a pure Ag conductor were selected as comparative examples (both did not contain glass frit). In the Ag / Pd conductor, the silver powder has a particle size of 0.1 μm to 0.5 μm and has a Pd
Was coated.

With respect to the Ag / Pd conductor and the pure Ag conductor (all seven types) of each weight ratio, on the first electrode (Ag / Pd = 80/20 glass 15%) formed on the vibration member 1 respectively. To form a second electrode. That is, seven types of vibrators A1 having different conductors of the second electrode were formed. A 30 μm Al lead wire (containing 1% Si for shape retention) was wire-bonded to this with a fully automatic ultrasonic wire bonder to form a lead wire S.

This was sealed in a hermetic seal package, and a high-temperature operation durability test at 85 ° C. was performed. The operation is performed at the natural frequency of the vibration member 1 (about 3.2 kHz).
The amplitude was set to 8 μm (a value from one peak to the other peak of the vibration) at the tips of the arms 4 and 5 (the portions of the detection electrodes 16 and 17). Further, the reason why the temperature is set to 85 ° C. is that the diffusion between Ag and Al easily proceeds at a high temperature as described in the requirements, as well as the upper limit of the operating temperature of the sensor.

FIGS. 4 and 5 show the endurance results. FIG.
Means Ag / Pd conductor (Ag / Pd = 90/10) and pure A
In the g conductor (Ag = 100), the change in bonding strength at every predetermined operation time was examined. The horizontal axis indicates the operation time (hr),
The vertical axis indicates the bonding strength (gf) after a predetermined operation time. In FIG. 4, Ag / Pd conductors are indicated by white circle marks, and pure A
The g conductor is indicated by white and black triangle marks.

The joining strength is determined by pulling the lead wire S by a tensile tester and breaking the lead wire S at the neck N shown in FIG. 3 (neck cut mode, corresponding to white circles and white triangle marks in FIG. 4), or The lead wire S peels off at the joint with the second electrode (peeling mode, FIG.
The middle and black triangle marks are equivalent).

On the other hand, FIG. 5 shows the dependency of the bonding strength on the Pd content. The horizontal axis indicates the Pd and A in the second electrode.
g of Pd (0, 2, 5, 8, 1
0, 20, 30% by weight), and the vertical axis represents 85 ° C., 100 ° C.
The bonding strength (gf) after operating for 0 hours is taken. The bonding strength is the same as in FIG. In FIG. 5, the black circle mark indicates
In the peeling mode, the white circle mark indicates the neck breaking mode.

In the case of a pure Ag conductor, at 500 hours, the bonding strength is reduced in some of the lead wires, a peeling mode (black triangle mark) is generated, and at 1000 hours, the bonding strength is significantly reduced. All the lead wires are in the peeling mode. On the other hand, in the electrode to which 5 to 30% by weight of Pd was added, the bonding strength did not decrease even after the durability of 1000 hours, and the lead wire did not peel off.

In FIG. 4, the joining strength (open circle, open triangle mark) in the neck breaking mode with time is shown.
However, this is due to the fact that the strength of the neck portion N itself of the lead wire S has deteriorated due to the high temperature environment, and has no relation to the bonding strength between the lead wire and the electrode. Conceivable. Here, the peeling surface of the lead wire at the electrode in the endurance experiment described above has a form in which the surface of the electrode is peeled off as a result of observation with a scanning electron microscope (SEM). (AE
Elemental analysis of the deposits on the lead wire in S) showed that A
It was found to be a diffusion layer of g and Al.

From this, it is considered that the peeling of the lead wire and the decrease in the bonding strength are caused by the progress of the interdiffusion of Ag-Al in a high-temperature environment, thereby generating a low-strength diffusion layer. Here, in the endurance experiment, the effect of the Pd content on the formation of the Ag and Al diffusion layers was examined. FIG. 6 shows the results.
In each conductor (Pd content, 0, 5, 10, 30% by weight), the diffusion layer grows with time.
In the case of the d conductor, the formation of a diffusion layer at the joint interface with the lead wire is suppressed to be lower than that in the case of the pure Ag conductor.
It was found that the larger the amount of addition, the greater the effect of suppressing the diffusion layer.

Therefore, as described above, it is considered that the interdiffusion between Ag and Al is suppressed by the addition of Pd, and as a result, the durability of the bonding strength can be improved. Therefore, in order to improve the durability of the bonding strength, the second electrode preferably has a Pd content of 5% by weight or more. FIG.
In the endurance test shown in FIG. 5 and FIG. 5, Pd was not carried out for 30% by weight or more, but even if it was more than 30% by weight, the same effect as 5 to 30% by weight was obtained due to the effect of suppressing the diffusion of Pd. Is considered to be obtained.

It is to be noted that Pd has a higher melting point (Pd: about 1555 ° C., Ag: about 960 ° C.) than Ag, and too much Pd is considered to adversely affect the sinterability of the electrode. Further, Pd is more expensive than Ag, so that Pd is practically 50%.
% By weight or less is preferred. As described above, according to the first embodiment, by using an Ag / Pd conductor as the electrode material, a piezoelectric vibrator having an electrode configuration excellent in bonding strength with a lead wire connected by ultrasonic WB is provided. An angular velocity sensor can be provided.

(Second Embodiment) FIG. 7 shows the structure of the second embodiment. In the second embodiment, the vibrating body (piezoelectric vibrating body) A1 in the first embodiment is exposed to a nitrogen atmosphere. It is characterized by having. Although the shell (cover) covering the vibrating body A1 has been described in the first embodiment, FIG.
FIG. 3 is a side perspective view of the vibration member 1 viewed from the Y2 surface side. In the second embodiment, parts different from those in the first embodiment will be mainly described, and the same parts will be denoted by the same reference numerals in the drawings and description thereof will be omitted.

The vibrating body A1 and the lead wire S are covered by a shell (lid) 7 adhered to the outer periphery of the substrate 2, and the vibrating body A1 is hermetically sealed to the outside by the shell and the insulating glass 2a. Has been stopped. An internal space 8 sandwiched between the shell 7 and the substrate 2 is filled with nitrogen gas.
Here, the attachment of the shell 7 to the substrate 2 is performed after the connection of the lead wire S and the electrodes 110 to 117 is performed.

As described above, the inner space 8 was set to the nitrogen atmosphere because the aluminum lead wire S and the electrode 11 made of Ag / Pd were used.
This is because it has been found that good bonding strength is exhibited in bonding with 0 to 117. Next, the effect of the nitrogen atmosphere on the joining of the two will be specifically described. The purpose of the nitrogen atmosphere is to aim at the effect of preventing oxidation of the electrode portion in the first place. During the experiment, the present inventors changed the material of the electrode connected to the aluminum lead wire S and the ultrasonic WB in a nitrogen atmosphere to Ag / P.
It has been found that there is a difference in bonding strength between the case of using d conductor and the case of using Ag conductor.

In the experiment, the electrodes 110 to 11 on the vibrating member 1 were
As No. 7, an Ag / Pd conductor (80/20) and an Ag / Pt conductor (99/1) were produced. Ultrasonic wave W between each conductor and aluminum lead wire S
B, and then at high temperature (380 ° C) for a predetermined time (1
After standing for 10 hours), a normal tensile strength test was performed to determine the bonding strength.

The results of this experiment are shown in the graph of FIG. FIG.
Shows the change in the bonding strength (horizontal axis, kg) between the lead wire and the electrode every predetermined time (vertical axis, hr). (A)
Is Ag / Pd conductor (80/20), (b) is Ag
/ Pt conductor. The Ag / Pt conductor is Pt
(Platinum) is 1% by weight and is substantially an Ag conductor;
Hereinafter, it is referred to as an Ag conductor.

From FIG. 8, when the electrode material is an Ag conductor,
While having a high joining strength at the beginning of joining, the joining strength decreases with time. On the other hand, Ag /
In the case of the Pd conductor, there is almost no change in the joining strength with the passage of time, and the joining strength at the beginning of the joining is maintained. In order to investigate the cause of the difference in bonding strength in the high temperature storage experiment,
As a result of SEM observation of the peeled surface of the lead wire at the electrode, it was found that there was a difference in the diffusion layer formed at the bonding interface.
This is shown in FIG. In FIG. 9, (a) shows Ag /
In the case of a Pd conductor, (b) is a case of an Ag conductor.

In the case of an Ag / Pd conductor, A
An Ag—Al diffusion layer (alloy layer) and an Ag—Pd—Al diffusion layer (alloy layer) are formed in this order from the lead wire side of FIG.
In (a), it has peeled off from Ag-Pd). On the other hand, in the case of the Ag conductor, an Ag-Al diffusion layer (alloy layer) is formed at the separation interface, and the Ag-Al diffusion layer is separated from the electrode at this diffusion layer portion.

From the results of the observation of the peeled surface, the following is considered. In the case of the Ag conductor, at the beginning of the joining, the aluminum wire and the Ag conductor are directly joined, and have a high joining force. However, in a nitrogen atmosphere, an Ag-Al diffusion layer is gradually formed at the bonding interface. Since the bonding strength of the diffusion layer with the Ag conductor is weak, the bonding strength is deteriorated if left in a nitrogen atmosphere.

On the other hand, in the case of an Ag / Pd conductor, in a nitrogen atmosphere, an Ag—Al diffusion layer and an Ag—Pd—Al diffusion layer are gradually formed at the bonding interface. However, this double diffusion layer is a diffusion layer having high bonding properties to the aluminum wire and the Ag / Pd conductor. In other words, Ag / P
In the case of the d conductor, it can be said that the bonding strength is secured by forming the Ag-Pd-Al diffusion layer.

Therefore, even if the vibrating body A1 is exposed to the nitrogen atmosphere, that is, even if the electrodes 110 to 117 electrically connected to the aluminum lead wire S by the ultrasonic WB are exposed to the nitrogen atmosphere, the electrodes 110 to 117 are exposed. Is formed of a thick silver film containing palladium, so that the bonding strength is not deteriorated. (Third Embodiment) FIGS. 10 and 11 show a third embodiment of the present invention. The piezoelectric vibration element of the present embodiment is also applied as a piezoelectric vibration type angular velocity sensor. The angular velocity sensor supports a vibrating body (piezoelectric vibrating body) A2 including a vibrating member 101 made of a piezoelectric body (PZT in the present embodiment) and electrodes formed on the vibrating member 101, and supports the vibrating body A2. The vibration member 1 includes a substrate 109 to be fixed.
The configuration is such that the electrode formed on the substrate 01 and a lead terminal (connection terminal) P of the substrate 109 are electrically connected by a lead wire S.

In the present embodiment, unlike the above embodiments, a vibrating member 101 made of a four-legged tuning fork-shaped piezoelectric material as shown in the figure is used. FIG. 10 is a perspective view of the angular velocity sensor according to the present embodiment. The vibration member 101 includes four quadrangular prism-shaped arm portions (vibration portions) 102 arranged substantially in parallel,
103, 104, and 105, and each arm section 102 to 105
And a common connecting portion 106 for fixing and supporting one end of the common fork, and has a comb-shaped tuning fork shape. The pair of inner arms 103 and 104 is configured as a drive arm, and the pair of outer arms 102 and 105 is configured as a detection arm.

Here, as shown in FIG.
The arrangement direction of 2 to 105 is the y axis, and the arm units 102 to 105
The xyz orthogonal coordinate system is constructed by setting the longitudinal direction of the z axis to the z axis and the thickness directions of the arm portions 102 to 105 and the connecting portion 106 to the x axis. Here, the z-axis is a pair of inner arms 103, 1
It is located in the center between 04. Hereinafter, the present embodiment will be described based on the xyz rectangular coordinate system. Note that the x-axis direction refers to a direction parallel to the x-axis, and the y-axis, z-axis
The same is true for the axis.

The surface of the vibrating member 101 that is substantially perpendicular to the x-axis and that faces the substrate 109 (second side surface)
Is defined as an X2 plane, and a surface (first side surface) opposite to the X2 plane is defined as an X1 plane. Also, in the vibrating member 101, of the outer peripheral surfaces of the pair of outer arms 102 and 105 orthogonal to the y axis, the surface on the arm 102 side is defined as the Y2 surface, and the arm 1
The surface on the 05 side is defined as a Y1 surface.

Each of the arms 102 to 105 and the connecting portion 106 are connected to each other as shown by a white arrow in FIG.
Polarization processing is performed uniformly in the x-axis direction from one surface to the X2 surface (the direction may be reversed). 107
Is a supporting portion formed of a metal such as 42 alloy, for example, and has a substantially D-shape with a narrow central portion, and the narrow portion is configured as a torsion beam 108. A portion located on one end side of the torsion beam 108 is a connecting portion side connecting portion 107 fixed to the connecting portion 106.
a, a portion located on the other end side of the torsion beam 108 is a substrate-side connection portion 10 fixed to a spacer 107c described later.
7b.

The torsion beam 108 is connected to the connecting portion 106
In the figure, the arm portions 103 and 104 are positioned so as to extend from a substantially central portion between the support portions of the pair of inner arm portions 103 and 104 to the side opposite to the arm portions 102 to 105 in the z-axis direction. As shown in FIG. 10, the support portion 107 is provided on one side with the connecting portion 10.
6 and the other spacer 10 on the other side.
It is joined and fixed to the substrate (base) 110 by welding or the like via 7c.

Therefore, the vibration member 101 is supported in a floating state on the substrate 109 via the support portion 107 and the spacer 107c. Further, the central axis of the torsion beam 108 substantially coincides with the z-axis, in other words, the torsion beam 108 is located substantially on the center line of the vibration member 101. Next, X1, X2, Y1, Y on the vibration member 101
An electrode configuration formed on two surfaces will be described. The electrode configuration is shown in the developed view of FIG. In FIG. 11, (a) is the X1 plane, (b) is the X2 plane, (c) is the Y1 plane,
(D) shows an electrode configuration on the Y2 plane.

Reference numeral 120 denotes a drive electrode for driving the vibration member 101, which is formed continuously on the X1 plane from the outer peripheral side of the arm section 103 through the connecting section 106 to the outer peripheral side of the arm section 104. I have. Reference numeral 121 denotes a reference electrode for monitoring the driving state and performing self-excited oscillation. The reference electrode 121 extends from the inner peripheral side of the arm 103 to the inner peripheral side of the arm 104 on the X1 plane. It is formed continuously.

In the X1 plane, the connecting portion 106 has a pad electrode for detection (detection electrode) for outputting an angular velocity detection signal from angular velocity detection electrodes 124 to 126 described later.
122, and an extraction pad electrode (extraction electrode) 123 electrically connected to common electrodes 130 to 133 described later. The detection pad electrode 122 is located in the middle of an extraction electrode 128 described later, and is electrically connected to the angular velocity detection electrodes (detection electrodes) 124 to 126 via the extraction electrode 128. The extraction pad electrode 123 is located at the end of an extraction electrode 138 described later.
Through the common electrodes 130 to 133.
Each of the pad electrodes 122 and 123 is formed to be wider than each of the lead electrodes 128 and 138 that are conductive.

Each of these electrodes (first electrode) on the X1 plane
Similarly to the above embodiments, 120 to 123 have WB electrodes (second electrodes) 150 to 153 at the portions of the surface where the lead wires S are connected.
(See FIG. 3). The angular velocity detection electrodes 124, 125, and 126 are electrodes for detecting a detection vibration generated by a Coriolis force when an angular velocity is generated. The angular velocity detection electrode 124 is formed over substantially the entire area of the arm section 105 on the Y1 plane. On the other hand, the angular velocity detection electrode 125 extends over substantially the entire area of the arm section 102 on the X1 plane, and the angular velocity detection electrode 126
The surface is formed over substantially the entire area of the arm portion 102.

Here, all the angular velocity detecting electrodes 124 to 1
As shown in FIG. 11, the reference numeral 26 is electrically connected and connected by extraction electrodes 127, 128 and 129 formed on the respective surfaces. The angular velocity detection electrodes 124 and 125 are connected to the extraction electrode 127 (on the Y1 plane) and the extraction electrode 128 (X1
On the plane), and the angular velocity detecting electrodes 125 and 12
6 is connected via an extraction electrode 129 (on the Y2 plane).

As described above, all the angular velocity detecting electrodes 124 to 126 are connected to the angular velocity detecting electrodes 12 on the X1 plane.
5 is connected to the detection pad electrode 122 via the extraction electrode 128 extending to the connecting portion 106 side. The common electrodes 130, 131, 132 and 133 are connected to the drive, reference, pads and angular velocity detection electrodes 120 to 126, respectively.
Of the reference potential. The common electrode 130 is formed over substantially the entire area of the arm section 105 on the X1 plane, and the common electrode 131 is formed over substantially the entire area of the arm section 105 on the X2 plane. The common electrode 132 is connected to the arm 1 on the X2 plane.
03 from almost the entire area through the connecting portion 106 to the arm portion 104
Are formed continuously over substantially the entire area of the common electrode 1.
Reference numeral 33 is formed over substantially the entire area of the arm section 102 on the Y2 plane.

Here, all the common electrodes 130 to 133
As shown in FIG. 11, are electrically connected to each other by extraction electrodes 134, 135, 136 and 137 formed on each surface. The common electrodes 130 and 131 are connected via an extraction electrode 134 (Y1 plane), and the common electrodes 131 and 132 and the common electrode 133 are connected to the extraction electrodes 135, 1
36 (both on the X2 plane) and the extraction electrode 137 (Y2 plane).

Then, as described above, all the common electrodes 130
133 are electrically connected to the extraction pad electrode 123 via the extraction electrode 138 extending from the common electrode 130 to the connecting portion 106 side in the X1 plane. Each of the above electrodes 1
20 to 138 and 150 to 153 are made of silver (A) containing conductive palladium (Pd), similarly to the above embodiments.
g) It is formed by a thick film.

[0086] Of the surfaces of the vibration member 101 orthogonal to the y-axis direction, the opposing surfaces of the arm portions 102 and 103, the opposing surfaces of the arm portions 103 and 104,
No electrodes are formed on the opposing surfaces of the arm 104 and the arm 105. Further, the drive electrode 120 and the reference electrode 1
21, angular velocity detection electrode 124 and common electrodes 130, 13
1, the angular velocity detecting electrodes 125 and 126 and the common electrode 13
Nos. 3 are formed with a gap therebetween and are not conductive.

As shown in FIG. 10, the drive electrode 120, the reference electrode 121, both pad electrodes 122, 1
Each of the electrodes 23 is the WB electrode 150 described above.
Through 153 to be electrically connected to the conductive lead wire S. These lead wires S are further connected to the substrate 109.
Are connected to the respective lead terminals P provided on the respective terminals, and the respective electrodes 120 to 123 and 150 to 153 are connected to the respective lead terminals P.
Is electrically connected to Each of these lead wires S has a wire diameter of 30 μm whose main component is Al, as in the above embodiments.
And the connection is made by ultrasonic WB. Accordingly, a signal from a drive / detection circuit (external circuit) not shown is input to and output from the vibration member 101 from the lead terminal P via the electrodes 120 to 123 and 150 to 153.

The vibrating body A2 of this embodiment also has an airtight structure with respect to the outside, is configured as an angular velocity sensor, and is mounted at an appropriate position on an object to be measured (vehicle or the like), similarly to the above embodiments. The angular velocity sensor according to the present embodiment operates as follows by the drive / detection circuit. First, by applying an AC voltage between the drive electrode 120 and the common electrode 132, the pair of inner arms 103 and 104 are bent in the y-axis direction symmetric with respect to the z-axis (that is, the center line of the vibration member 101). Resonate in vibration mode. The output from the reference electrode 121 is monitored as the amplitude at that time, and self-excited oscillation (self-excited oscillation) is performed using the drive / detection circuit so that the output from the reference electrode 121 becomes constant.

Next, when an angular velocity is input around the z-axis, Coriolis force is generated in the pair of vibrating inner arms 103 and 104, and these arms 103 and 104 are vibrated.
Receive forces in directions opposite to each other in the x-axis direction. At this time, since the pair of outer arms 102 and 105 are also coupled and vibrate in the x-axis direction, the vibration amplitude in the x-axis direction proportional to the angular velocity is detected as an output from the angular velocity detection electrodes 124 to 126 to detect the angular velocity. I do.

In this embodiment, as in the above embodiments, the electrode material is an Ag / Pd conductor, and the connecting portion has the two-layer structure.
It is possible to provide a piezoelectric vibrator and an angular velocity sensor having an electrode configuration excellent in bonding strength with a lead wire connected by B. Also in the present embodiment, if the vibrating body (piezoelectric vibrating body) A2 has a structure exposed to a nitrogen atmosphere as in the second embodiment, the bonding strength between the lead S and the electrode connected to the vibrating body deteriorates. Can be prevented.

(Fourth Embodiment) FIG. 12 shows a fourth embodiment of the present invention. The piezoelectric vibration element of the present embodiment is also applied as a piezoelectric vibration type angular velocity sensor. The angular velocity sensor includes a vibrating member (piezoelectric vibrating member) A3 including a vibrating member 201 formed of a piezoelectric member (PZT in the present embodiment) and electrodes formed on the vibrating member 201. Is supported and fixed on a substrate (not shown), and furthermore, a vibration member 20 is attached to a lead terminal (not shown) of the substrate.
The upper electrode 1 is electrically connected by a lead wire (not shown).

In this embodiment, a vibration member 201 made of a four-legged H-shaped tuning fork-shaped piezoelectric body as shown in the figure is used. FIG. 12 is a developed view of the vibrating body A3 as seen from front, rear, left and right. The vibration member 201 includes four parallel quadrangular prism-shaped arm portions (vibration portions) 202, 203, 204, and 205 and a connection portion 206. Here, one pair of arm portions 202 and 203 on one side is configured as a driving arm portion, and the other pair of arm portions 204 and 205 is configured as a detection arm portion.

The support portion (not shown) as shown in each of the above embodiments is fixed to the connection portion 206. The vibrating body A3 is connected to the substrate (not shown) via the support portion and the connection portion 206. )). In this embodiment, as shown in FIG. 12, the arrangement direction of the arm units 202 to 205 is the y axis, and the longitudinal direction of the arm units 202 to 205 is the z axis.
An xyz orthogonal coordinate system is configured with the thickness direction of the axes, the arm units 202 to 205 and the connecting unit 206 as the x axis. In addition,
The coordinates shown in FIG. 12 correspond to (a).

Further, one surface (first side surface) of the surface of the vibration member 201 which is substantially orthogonal to the x-axis is defined as an X1 surface,
The other surface (second side surface) is defined as an X2 surface. In the vibration member 201, one of the surfaces orthogonal to the y-axis and not facing each of the pair of arms 202 and 203 and 204 and 205 is defined as a Y1 surface, and the other surface is defined as a Y2 surface.
The vibration member 201 is uniformly polarized in the x-axis direction from the X1 plane to the X2 plane.

Next, X1, X2, Y on the vibrating member 201
1. The configuration of the electrodes formed on the Y2 plane will be described.
In FIG. 12, (a) is the X1 plane, (b) is the X2 plane,
(C) shows the Y1 plane, and (d) shows the Y2 plane. Reference numeral 207 denotes a drive electrode for driving the pair of arms 202 and 203 on one side.
06, the arm portion 203 is formed continuously. Reference numeral 208 denotes a reference electrode for monitoring a vibration state.
It is formed continuously on the outer peripheral side of the drive electrode 207 over the arm portion 203.

In the X1 plane, a pad for detection (detection electrode) for outputting an angular velocity detection signal from angular velocity detection electrodes 213 and 214 described later
209, 210, and extraction pad electrodes (extraction electrodes) 211, 212 that are electrically connected to a common electrode 215 described later. The detection pad electrode 209 is connected to the connecting portion 2.
At 06, the detection pad electrode 210 is located at a position closer to the Y2 surface and closer to the arm 205 at the connecting portion 206. On the other hand, the extraction pad electrode 211 is provided on the arm 204, and the extraction pad electrode 212 is provided on the arm 205.
It is located in.

Each electrode (first electrode) on the X1 plane
207 to 212 have WB electrodes (second electrodes) 257 to 262 in a portion of the surface to which the lead wire S is connected, as in the above-described embodiments.
(See FIG. 3). The angular velocity detection electrodes 213 and 214 are detection electrodes for detecting detection vibration generated by Coriolis force when an angular velocity is generated, and are formed on the Y2 surface of the arm 204 and the Y1 surface of the arm 205, respectively. As described above, the angular velocity detection electrode 213 is connected to the extraction electrode 2 on the Y2 plane.
16, and the angular velocity detection electrode 214 is electrically connected to the detection pad electrode 210 via the extraction electrode 217 on the Y1 surface.

The common electrode 215 is a common electrode serving as a reference potential for the driving, reference, pads, and angular velocity detecting electrodes 207 to 214. The common electrode 215 is formed over substantially the entire area of the X2 plane, and includes an extraction pad electrode 211 via an extraction electrode 218 on the Y2 plane, and an extraction pad electrode 212 via an extraction electrode 219 on the Y1 plane. Conducted. Therefore, both extraction pad electrodes 211,
The common electrode 212 and the common electrode 215 are also configured as one common electrode.

The above electrodes 207 to 219 and 257
262 are formed of a silver (Ag) thick film containing conductive palladium (Pd), similarly to the above embodiments. Although not shown in the present embodiment, similarly to the above embodiments, the drive electrode 207 and the reference electrode 2 on the X1 plane are used.
08, each of the two pad electrodes 209 to 212 is electrically connected to a conductive lead wire via the above-described WB electrodes 257 to 262, respectively, and further, a lead terminal and a drive / detection circuit (not shown). (External circuit).

Therefore, a signal from a drive / detection circuit (not shown) is supplied from the lead terminal to each of the electrodes 207 to 212 and 2
Input and output to and from the vibration member 201 via 57 to 262. Further, the vibrating body A3 of the present embodiment is also provided with an airtight structure to the outside, is configured as an angular velocity sensor, and is mounted at an appropriate position on an object to be measured (vehicle or the like), similarly to the above embodiments.

The operation of the present embodiment will be described. First,
By applying an AC voltage between the driving electrode 207 and the common electrode 215, the pair of arm portions 202 and 203 on one side resonate in a mode in which bending vibration is performed in the y-axis direction symmetric with respect to the center line of the vibration member 201. Let it. The output from the reference electrode 208 is monitored as the amplitude at that time, and self-excited oscillation (self-excited oscillation) is performed using the drive / detection circuit so that the output from the reference electrode 208 becomes constant.

Next, when an angular velocity is input around the z-axis, a Coriolis force is generated in the pair of vibrating arms 202 and 203 on one side.
Receive forces in directions opposite to each other in the x-axis direction. At this time, the pair of arms 204 and 205 on the other side are also coupled and vibrate in the x-axis direction. Therefore, the vibration amplitude in the x-axis direction proportional to the angular velocity is detected as an output from the angular velocity detection electrodes 213 and 214, and the angular velocity is detected. To detect.

Incidentally, also in the present embodiment, as in the above embodiments, it is possible to provide a piezoelectric vibrator and an angular velocity sensor having an electrode configuration excellent in bonding strength with a lead wire connected by ultrasonic WB. it can. Also in this embodiment, if the vibrating body (piezoelectric vibrating body) A3 has a structure exposed to a nitrogen atmosphere as in the second embodiment,
Deterioration of the bonding strength between the electrode connected to the lead wire S can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an angular velocity sensor according to a first embodiment of the present invention.

FIGS. 2A and 2B are development views of the configuration of each electrode formed on each surface of the vibration member according to the first embodiment, as viewed from front, rear, left and right of the vibration member, wherein FIG. Is the X2 plane,
(C) shows an electrode configuration on the Y1 plane, and (d) shows an electrode configuration on the Y2 plane.

FIG. 3 is a sectional view showing a connection configuration between a lead wire and an electrode in the first embodiment.

FIG. 4 is a view illustrating a configuration in which the electrode material is Ag / P in the first embodiment.
It is a graph which shows the joining strength change for every predetermined operation time in each case of a d conductor and a pure Ag conductor.

FIG. 5 is a graph showing Pd content dependence of bonding strength in the first embodiment.

FIG. 6 is a graph showing the relationship between the Pd content and the Ag content in the first embodiment.
5 is a graph showing the effect of Al and Al on the formation of a diffusion layer.

FIG. 7 is a side perspective view showing a configuration of an angular velocity sensor according to a second embodiment of the present invention.

FIG. 8 is a graph showing a change in bonding strength between a lead wire and an electrode for each predetermined operation time in the second embodiment;
(A) when the electrode material is an Ag / Pd conductor, (b)
g / Pt conductor.

FIG. 9 is an explanatory diagram showing a configuration of a peeling surface between a lead wire and an electrode in the second embodiment.

FIG. 10 is a perspective view illustrating a configuration of an angular velocity sensor according to a third embodiment of the present invention.

11A and 11B are development views of the configuration of the electrodes formed on each surface of the vibration member of FIG. 10 as viewed from front and rear and from the left and right of the vibration member, wherein FIG. 11A is an X1 plane, FIG. (C) is Y1
(D) shows the electrode configuration on the Y2 plane.

FIG. 12 is a development view of a piezoelectric vibrator according to a fourth embodiment of the present invention.

FIG. 13 is a configuration diagram showing a conventional angular velocity sensor.

FIG. 14 is a development view showing an electrode configuration formed on each surface of the vibration member of FIG.

[Explanation of symbols]

1, 101, 201: vibration member, 2, 109: substrate,
3, 107 ... support part, 4, 5, 102 to 105, 202
To 205: arm portion, 10, 11, 120, 207: drive electrode, 12, 13, 121, 208 ... reference electrode, 1
4, 15, 123, 211, 212 ... extraction electrode, 1
6, 17, 122, 209, 210 ... pad electrode, 2
0, 131, 132, 215 ... common electrode, 110 to 11
7, 150 to 153, 257 to 262: electrode for wire bonding, A1, A2, A3: piezoelectric vibrator, K1: substrate surface opposed to X2 surface of vibration member, P: lead terminal, S
... Lead wire, X1... First side face of vibration member, X2.

Claims (17)

[Claims] A vibration member (1, 101,
201) and electrodes (10-17, 110-110) formed on the vibrating member.
117, 120-123, 150-153, 207-2
12, 257 to 262), and a connection terminal (P) for inputting and outputting a signal to and from the vibrating member via the electrode, wherein the main components of the electrode and the connection terminal are made of aluminum. A piezoelectric vibrating element connected by a lead wire (S), wherein the electrode is formed of a silver thick film containing palladium. 2. The piezoelectric vibrating element according to claim 1, wherein the lead wire (S) is connected by an ultrasonic wire bonding method. 3. The piezoelectric vibrating element according to claim 1, wherein a wire diameter of the lead wire (S) is 50 μm or less. 4. The vibrating member (1, 10)
1, 201) first electrode (10 to 17, 120) on the main body side
To 123, 207 to 212) and the second electrode (110 to 117, 150 to 1) on the side where the lead wire (S) is connected.
53, 257 to 262), and the total thickness of the two-layer structure is 5 μm or more and 40 μm or less. Piezoelectric vibration element. 5. The second electrode (110-117, 15)
0-153, 257-262), the amount of palladium contained is 5% by weight or more based on the total amount of palladium and silver, The piezoelectric vibration element according to claim 4, wherein 6. The second electrode (110 to 117, 15)
0 to 153, 257 to 262), wherein the amount of contained palladium is 50% by weight or less based on the total amount of palladium and silver. 7. The first electrode (10-17, 120-
123, 207 to 212), wherein the content of glass or inorganic oxide is 1% by weight or more and 30% by weight or less based on the total amount thereof. Piezoelectric vibrating element. 8. The second electrode (110 to 117, 15)
0 to 153, 257 to 262)
The piezoelectric vibrating element according to any one of claims 4 to 7, wherein the content of the glass or the inorganic oxide is less than 1% by weight. 9. The piezoelectric vibrating element according to claim 1, wherein 90% by weight or more of the lead wire (S) is made of aluminum. 10. A vibrating portion having a prism shape (4, 5, 102 to
105, 202 to 205), and a vibrating member (1, 101, 201) made of a piezoelectric material having: z which is parallel to a longitudinal direction of the vibrating part in the vibrating member.
Of the pair of side surfaces (X1, X2) extending in the axial direction and facing each other, the drive electrodes (10, 10) provided on the first side surface (X1) are provided.
11, 110, 111, 120, 150, 207, 25
7), pat electrodes (16, 17, 116, 117, 12)
2, 152, 209, 210, 259, 260) and the common electrode (20, 13) provided on the second side surface (X2).
1, 132, 215) and extraction electrodes (14, 15, 114, 115, 12) provided on the first side surface and electrically connected to the common electrode.
3, 153, 211, 212, 261, 262) and a substrate (2, 109) disposed opposite to the second side surface.
And a support part (3, 107) for connecting the vibration member and the substrate and supporting the vibration member, and applying an AC voltage between the drive electrode and the common electrode, The vibrating portion (4, 5, 103, 104, 104) extends in the y-axis direction that is parallel to the side surface of
202, 203) and the vibrating portions (4, 4) generated by the angular velocity about the z-axis.
5, 102, 105, 204, and 205) an angular velocity sensor for detecting, via the pad electrode, a vibration state in an x-axis direction orthogonal to the y-axis and the z-axis. The substrate surface facing the second side surface (K
1) is provided with a connection terminal (P) for inputting / outputting a signal to / from an electrode provided on the vibrating member. The drive electrode, the pad electrode, and the extraction electrode are mainly composed of An angular velocity sensor connected to the connection terminal by a lead wire (S) made of aluminum, wherein each of the drive, pad, and take-out electrodes is formed of a thick silver film containing palladium. 11. The drive, putt and take-out electrodes (10, 11, 14 to 17, 110, 111, 114)
~ 117, 120, 122, 123, 150, 152,
153, 207, 209-212, 257, 259-2
62) are the first electrodes (10, 11, 14 to 17, 120, 12) on the main body side of the vibration member (1, 101, 201).
2, 123, 207, 209 to 212) and the second electrode (110, 111,
114 to 117, 150, 152, 153, 257, 2
The second electrode has an amount of palladium of 5% by weight or more based on the total amount of palladium and silver. An angular velocity sensor as described. 12. The second electrode (110, 111, 1).
14 to 117, 150, 152, 153, 257, 25
9 to 262), wherein the amount of contained palladium is 50% by weight or less based on the total amount of palladium and silver. 13. The angular velocity sensor according to claim 10, wherein the lead wire (S) is connected by an ultrasonic wire bonding method. 14. A vibration member (1, 10) made of a piezoelectric body.
1, 201) and electrodes (10-17, 110-110) formed on the vibrating member.
117, 120-123, 150-153, 207-2
12, 257 to 262), wherein the electrode is electrically connected to a lead wire (S) whose main component is aluminum, and is formed of a thick silver film containing palladium. A piezoelectric vibrating body, characterized in that: 15. The piezoelectric vibrating body according to claim 14, wherein the lead wire (S) is connected by an ultrasonic wire bonding method. 16. A vibration member (1, 10) made of a piezoelectric body.
1, 201) and the electrodes (10
-17, 110-117, 120-123, 150-1
53, 207 to 212, 257 to 262), and the electrode is formed of a silver thick film containing palladium, and a lead wire (a main component of which is made of aluminum). S), wherein at least the electrode is exposed to a nitrogen atmosphere. 17. The piezoelectric vibrator (A1, A2, A3)
The piezoelectric vibrating element according to claim 16, wherein is exposed to a nitrogen atmosphere.