JP2000022487A - Piezoelectric element and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element where a mechanical strength of a bonded part is not deteriorated even when silver or gold is used to coat a surface of a mount section of a piezoelectric body and a terminal and to realize its manufacture. SOLUTION: In the case of manufacturing a crystal vibrator, a noble metal layer made of a gold layer Au or a silver layer Ag is used to coat a surface of mount sections 51, 52 of a piezoelectric body 2 and a surface of an internal terminal 31 to enhance the electric characteristic or the like. Even in this case, since a thiol-film is formed to the surface of the mount sections 51, 52 of the piezoelectric body 2 and the surface of the internal terminal 31, even when the internal terminal 31 and the mount sections 51, 52 of the piezoelectric body 2 are adhered by a conductive adhesive 50, a high mechanical strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element in which terminals are joined to a mount portion of a piezoelectric body, and a method for manufacturing the same. More particularly, the present invention relates to a surface treatment technique for joining a mount portion of a piezoelectric body and a terminal with a conductive adhesive.

[0002]

2. Description of the Related Art A piezoelectric element such as a piezoelectric vibrator or an oscillator has a structure in which terminals are joined to a mount portion of a piezoelectric body (piezoelectric vibrating piece) such as a quartz piece by a conductive adhesive. In such a piezoelectric element, the surface of the mount portion of the piezoelectric body is conventionally covered with silver, and the surface of the terminal is covered with nickel.

For a piezoelectric element, a small and thin piezoelectric element, a high-precision and stable resonance frequency, and a CI value (crystal impedance / mechanical vibration of a vibrator are connected to a series resonance circuit of resistance, capacitance, and inductance). There is a demand for reduction of the resistance value when expressed as an equivalent circuit by the parallel capacitance with respect to the series resonance circuit), improvement of electrical characteristics, improvement of mechanical strength, and the like. Among these demands, to improve the accuracy and reliability in terms of electrical characteristics, the surface of the mount of the piezoelectric body is covered with a noble metal layer such as gold or silver, and the surface of the terminal is also made of gold or silver. It can be achieved by coating with a noble metal layer such as

[0004]

However, when the surfaces of the mount portion and the terminals of the piezoelectric body are covered with a noble metal layer such as gold or silver, it is possible to improve the accuracy and to improve the reliability in terms of electrical characteristics. Even so, gold or silver has a problem that the mechanical strength of the joint decreases due to poor adhesion to the conductive adhesive. In addition, if the bonding area between the mounting portion of the piezoelectric body and the terminal is reduced in order to reduce the size and thickness, the mechanical strength of the bonding portion is reduced accordingly, so that the surface of the mounting portion of the piezoelectric body and the surface of the terminal are reduced. The reduction in mechanical strength of the joint when coated with gold or silver is more pronounced.

Accordingly, an object of the present invention is to provide a piezoelectric element and a method of manufacturing the same, which do not reduce the mechanical strength of the joint even when the surfaces of the mount and the terminal of the piezoelectric body are coated with a noble metal layer made of gold or silver. Is to make it happen.

[0006]

According to the present invention, there is provided a piezoelectric element having a piezoelectric element and a terminal joined to a mount portion of the piezoelectric element by a conductive adhesive. The mounting part and the terminal
The surface is covered with a noble metal layer made of gold or silver, and a thiol-treated film is formed on the surface of the noble metal layer of at least one of the mount portion of the piezoelectric body and the terminal. .

[0007] The thiol used in the present invention is R-SH (where R is an organic group such as an alkyl group, preferably an alkyl group having 3 or more carbon atoms, or performs chemical adsorption or bonding with a resin component). Organic group having a functional function). If the thiol is adhered to the surface of a metal film or the like, the adhesion between the metal film surface and the resin is improved. It is considered that the reason is that the thiol forms a complex on the surface of the metal film to direct the thiol group toward the metal film and to direct the organic group having high affinity to the resin component to the outside.
Therefore, even if adhesion is poor when a conductive adhesive is directly applied to a noble metal layer such as gold or silver, if a thiol-treated film is formed on the surface of the noble metal layer, the noble metal layer and the conductive adhesive Adhesion is improved. Therefore, even if both the mount portion and the terminal of the piezoelectric body are covered with a noble metal layer made of gold or silver, the mount portion and the terminal of the piezoelectric body are joined with a high mechanical strength via the conductive adhesive. be able to.

In the present invention, the thiol-treated film may be formed on the surface of the noble metal layer of one of the mount portion of the piezoelectric body and the terminal. It is preferably formed on the surface.

To manufacture the piezoelectric vibrator according to the present invention,
After the surfaces of the mounting portion of the piezoelectric body and the terminals are covered with a noble metal layer made of gold or silver, the conductive body is applied with a conductive adhesive applied to at least one of the mounting portion of the piezoelectric body and the terminals. Before joining the mounting portion and the terminal, a thiol-treated film is formed on the surface of the noble metal layer of at least one of the mounting portion of the piezoelectric body and the terminal.

Here, it is preferable that the thiol-treated film is formed on the surface of the noble metal layer on both the mounting portion of the piezoelectric body and the terminal.

The formation of such a thiol-treated film can be performed by, for example, contacting the surface of the noble metal layer on which the thiol-treated film is to be formed with a treatment solution obtained by diluting thiol with a solvent. In the present invention,
The thiol adheres to the noble metal layer only by bringing the treatment liquid into contact with the noble metal layer, and the surface modification of the noble metal layer is performed by merely attaching the thiol to the surface of the noble metal layer to form a monomolecular layer. Therefore, even if the thiol-treated film is interposed at the interface between the piezoelectric body mount portion and the conductive adhesive or the interface between the terminal and the conductive adhesive, the electrical connection between the piezoelectric body mount portion and the terminal is possible. There is no problem with proper connection.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the overall structure of the piezoelectric element. 2A is a perspective view of a piezoelectric element on which an electrode film is formed in a piezoelectric element to which the present invention is applied, as viewed from one arm side, and FIG. 2B is a perspective view as viewed from the other arm side. ,
(C) is a side view as seen from the base.

[Overall Structure of Piezoelectric Element] As shown in FIG. 1, in a tuning-fork type quartz vibrator 1 (piezoelectric element), first and second arms 22 and 23 are arranged in parallel from a base 21 in the same direction. Body 2 formed of a thin plate-shaped quartz piece having a tuning-fork-shaped planar shape extending therefrom, and two internal terminals 31 for mounting portions 51 and 52 formed on a base 21 of the piezoelectric body 2.
Are composed of a stem 30 connected by a conductive adhesive 50 and a case 35 accommodating the piezoelectric body 2, and the case 35 and the stem 30 keep the inside airtight.

As shown in FIGS. 2A and 2B, two electrode films 41 and 42 are separately formed on the surface of the piezoelectric body 2 with a predetermined gap 10 on the upper surface and the lower surface, respectively. By applying an AC voltage to each of the electrode films 41 and 42 from the external terminal 33 (see FIG. 1) of the stem 30, the arms 22 and 23 vibrate at a predetermined frequency.

As will be described in detail later, the electrode films 41 and 42 have a two-layer structure of a base metal film made of a chromium layer and a gold electrode layer. In the arms 22 and 23, each electrode film 4
Since the gap 10 between the electrodes 1 and 42 is extremely narrow, the electrode film 4
Since there is a possibility that a short circuit may occur between the first and second electrodes 42, a surface protection film (not shown) may be formed on the surfaces of the electrode films 41 and 42.

In the piezoelectric body 2, the electrode films 41 and 42 are also formed on each side end surface to connect the electrode films 41 and 42 between the upper surface and the lower surface. However, since it is necessary to insulate and separate the electrode films 41 and 42 at predetermined locations on the side end surfaces, for example, the side end surfaces between the base portions of the arm portions 22 and 23 may be provided on the side end surfaces inside. Has a considerably wide gap 11 formed therein. Further, as shown in FIG. 2C, mount portions 51 and 52 are formed on the base portion 21 of the piezoelectric body 2 to connect the internal terminals 31 to the electrode films 41 and 42 by the conductive adhesive 50, respectively. This base 2
Neither of the electrode films 41 and 42 is formed on the first side end surface 210, and the entire side end surface 210 functions as the gap 12. Here, the conductive adhesive 50 is a so-called silver paste or the like, and conductive particles such as silver are compounded in the resin component. In joining each of the internal terminals 31 to the mount portions 51 and 52, the conductive adhesive 50 is used.
May be used alone, or the mechanical strength of the conductive adhesive 50 and the non-conductive adhesive (non-conductive adhesive) may be increased in combination.

[Structure of Joining Portion] FIG.
FIG. 4 is an enlarged cross-sectional view showing a joint structure between a mount portion and an internal terminal in FIG.

As shown in FIG. 3, the crystal resonator 1 of the present embodiment
Then, in order to improve the electrical characteristics and the like, the mount portions 51 and 52 (electrode films) cover the surface of the chromium layer Cr as a base film with a noble metal layer made of a gold layer Au or silver Ag. As for the terminal 31, the surface of the nickel layer Ni formed as a base film on the surface of the core material is covered with a noble metal layer made of a gold layer Au or silver Ag.
However, if the surfaces of the mount portions 51 and 52 (electrode films) or the surfaces of the internal terminals 31 are covered with a noble metal layer composed of a gold layer Au or a silver layer Ag, the internal terminals 31 and the mount portions 51 and 52 (electrodes) Film) as conductive adhesive 50
However, since the adhesion between the resin component of the conductive adhesive 50 and the noble metal layer composed of the gold layer Au or the silver layer Ag is poor, sufficient bonding strength cannot be obtained. Therefore, in this embodiment, the mounting portions 51 and 52 of the piezoelectric body 2 and the internal terminals 3
On the surface of one noble metal layer (gold layer Au or silver layer Ag), thiol-treated films 60 and 61 are formed. Accordingly, since the conductive adhesive 50 and the mount portions 51 and 52 of the piezoelectric body are bonded via the thiol-treated film 60, the adhesion is excellent. Further, since the conductive adhesive 50 and the internal terminals 31 are adhered via the thiol-treated film 61, the adhesion is excellent. Therefore, the mounting portion 5 of the piezoelectric body 2
1, 52 and the internal terminal 31 are joined by a conductive adhesive 50 with sufficient mechanical strength.

The thiol-treated films 60 and 61 used here
Is a monomolecular film that is adhered to the internal terminals 31 and the mounting portions 51 and 52 of the piezoelectric body 2 by contacting a processing solution obtained by diluting thiol with a solvent, as described later. The thiol used here is R-SH (where R is an organic group such as an alkyl group, and preferably has 3 carbon atoms).
The above alkyl group or an organic group having a functional function of chemically adsorbing or bonding to a resin component), and forming a complex with the surface of the gold layer Au or the silver layer Ag even if only a monomolecular layer is formed. , The thiol group SH is directed toward the surface of the gold layer Au or the silver layer Ag, and the organic group having a high affinity for the resin is directed outward, so that the conductive adhesive 50 and the mounting portion 51 of the piezoelectric body 2 It can be considered that the adhesion between the conductive adhesive 52 and the internal terminal 31 is improved. That is, the thiol has an organic group having a high affinity for the resin component of the conductive adhesive directed outward, and the organic chain of the resin component of the conductive adhesive and the organic chain of the thiol are entangled, so that the thiol has an adhesive property. Is considered high. Alternatively, it is considered that the adhesion is high because the resin component of the conductive adhesive and the organic group of the thiol are chemically adsorbed or bonded. Therefore, as the thiol, R when represented by R-SH is preferably an alkyl group having 3 or more carbon atoms, and the longer the straight chain, the higher the affinity with the resin component of the conductive adhesive. . Further, even if the organic group of the thiol is an organic group having a functional function of chemically adsorbing or bonding to the resin component of the conductive adhesive, the adhesion to the resin component of the conductive adhesive is high.

[Outline of Method of Manufacturing Crystal Resonator 1] A method of manufacturing the crystal resonator 1 having such a configuration will be described with reference to FIG. FIG. 4 shows two arms 22 and 23 of the piezoelectric body 2.
2 shows a cross section of a portion corresponding to.

First, as shown in FIG. 4A, a wafer W of a cut crystal is polished and cleaned, and
As shown in (B), a chromium layer Cr and a gold layer Au are formed with a thickness of several hundred angstroms by a sputtering method or a vapor deposition method. Here, the chromium layer Cr is formed because the adhesion of the crystal to the wafer W is poor only with the gold layer Au.

Next, after applying a liquid photoresist PR1 on the surface of the gold layer Au, the photoresist PR1 is exposed and developed into a pattern of a tuning fork shape, and as shown in FIG. A mask M1 is formed. next,
Gold layer Au and chromium layer C via resist mask M1
r is etched to leave the gold layer Au and the chromium layer Cr in a tuning fork shape, as shown in FIG. Next, the wafer W is etched with an etchant using hydrofluoric acid and ammonium fluoride using the gold layer Au and the chromium layer Cr as a mask, and quartz is formed into a tuning fork shape as shown in FIG. This crystal blank is the piezoelectric body 2.

Next, a resist mask M1 on the piezoelectric body 2,
The gold layer Au and the chromium layer Cr are all removed, and FIG.
As shown in FIG. 5, a chromium layer Cr and a gold layer Au (or silver layer Ag) for forming the electrode films 41 and 42 and the mount portions 51 and 52 are formed again by the sputtering method. Although not shown, in this step, weight portions for frequency adjustment, which will be described later, are attached to the arms 22 and 23 of the piezoelectric body 2.
A gold layer (or silver layer) is formed on the tip side (metal film forming step).

Next, as shown in FIG.
A liquid photoresist PR2 is applied to the surface of the gold layer Au (or silver layer Ag). (Resist coating step).

Next, as shown in FIG. 4G, a photoresist PR2 is applied to each of the electrode films 41 and 42 and the
Exposure and development to the pattern shape of 1, 52, each electrode film 4
A resist mask M2 having the outer shapes of the reference numerals 1 and 42 and the mount portions 51 and 52 is formed (exposure / development step).

Next, as shown in FIG. 4H, the gold layer Au (or silver layer Ag) and the chromium layer Cr are etched through the resist mask M2. Thereafter, the resist mask M2 is removed. As a result, FIG.
As described with reference to (B) and (C), the gold layer Au
(Or silver layer Ag) and chromium layer Cr are electrode film 41,
The electrode films 41 and 42 and the mount portions 51 and 52 made of the base metal film made of the chromium layer Cr and the gold layer Au (or the silver layer Ag) can be formed while being left in the pattern shape of the base portion 42 and the mount portions 51 and 52 ( Patterning step).

Next, a step of forming a surface protective film is performed (FIG. 4).
(I)).

With respect to the piezoelectric body 2 on which the electrode films 41 and 42 and the mounting portions 51 and 52 have been formed in this manner, the mounting process is not immediately performed, and as shown in FIG.
The thiol is immersed in a processing solution L1 in which a thiol is dissolved in a solvent such as alcohol or ketone. Thereafter, as shown in FIG. 5B, the piezoelectric substance 2 is immersed in the same solvent as the processing liquid L1, for example, alcohol L2. Is immersed, the piezoelectric body 2 is lightly rinsed, and the excess processing liquid L1 is removed from the surface of the piezoelectric body 2.
Is removed. Thereafter, drying is performed. The thiol used here is R-SH (where R is an organic group such as an alkyl group, preferably an alkyl group having 3 or more carbon atoms, or an organic group having a functional function of chemically adsorbing or bonding with a resin component). The thiol adheres to the surface of the gold layer Au (or silver layer Ag) as the thiol-treated film 60 as shown in FIG. 3 by simply immersing the piezoelectric body 2 in the processing liquid L1 (thiol). Adhesion treatment).

As shown in FIG. 3, also for the internal terminal 31, as a base metal film, a nickel layer Ni alone or a copper layer and a nickel layer are formed, and then a gold layer A is formed.
u (or silver layer Ag). Then, similarly to the piezoelectric body 2, the internal terminals 31 are immersed in the treatment liquid L1 described with reference to FIG. 5A, and then immersed in alcohol L2 or the like shown in FIG. After removing excess processing liquid L1 from the surface of the terminal 31, drying is performed.
As a result, as shown in FIG. 3, a thiol-processed film 61 is formed on the surface of the gold layer Au (or silver layer Ag) covering the surface of the internal terminal 31 (thiol attachment process).

In this manner, the thiol-treated films 60, 61
As shown in FIG. 3 and FIG. 6, the stem 3 is mounted on the mounting portions 51 and 52 formed on the base 21 as shown in FIGS.
0 internal terminals 31 are electrically and mechanically connected by a conductive adhesive 50.

The mounting portions 51, 5 and 5 of the piezoelectric body 2
The conductive adhesive 50 is applied to one or both of the surface of the gold layer Au (or silver layer Ag) and the surface of the gold layer Au (or silver layer Ag) of the internal terminal 31. Thereafter, the internal terminals 31 are stacked on the mount portions 51 and 52 of the piezoelectric body 2 via the conductive adhesive 50, and a hardening process is performed.
In this manner, the mount 5 of the piezoelectric body 2 covered with the gold layer Au (or silver layer Ag) to which the thiol has been attached is applied.
The internal terminals 31 covered with a gold layer Au (or a silver layer Ag) to which thiol has been attached are bonded by a conductive adhesive 50.

Next, the frequency adjustment of the piezoelectric body 2 at this stage is performed by laser trimming the weights formed at the tips of the arms 22 and 23 of the piezoelectric body 2 and then to the case 35 in the vacuum chamber. The stem 30 is press-fitted (sealing step) to manufacture the crystal unit 1. Thereafter, the characteristic inspection of the crystal unit 1 is performed (inspection step).

[Other Examples and Their Evaluation Results] In the above embodiment, the mounting portions 51 and 52 of the piezoelectric body 2
Although the thiol attachment process has been performed on both the internal terminals 31 and the internal terminals 31, the thiol attachment process may be performed on only one of them.

Up to this point, as an example of the piezoelectric element, a tuning fork type quartz resonator has been used for the piezoelectric body. Next, the thiol attachment process is the same, and the effect of the thiol attachment process is large.
The evaluation result of a thickness-sliding quartz crystal resonator having a rectangular piezoelectric body as shown in FIG.

Table 1 shows the configurations of the quartz resonators according to the examples and comparative examples of the present invention, and the evaluation results thereof.

[0037]

[Table 1]

Here, as the piezoelectric body 2, the mount 5
1 and 52 coated with a gold layer Au are used.
As No. 1, one covered with a gold layer Au or a silver layer Ag was used. Further, in each of the cases where the bonding area between the piezoelectric body 2 and the internal terminal 31 was set to 0.72 mm ² and 0.36 mm ² , the thiol attachment processing was performed on both the piezoelectric body 2 side and the internal terminal 31 side. Sample (Examples 1 to 3)
4), the thiol attachment process is performed only on the piezoelectric body 2 side,
Samples not performed on the side of the internal terminal 31 (Examples 5 to 8),
And a sample in which thiol attachment processing is performed only on the side of the internal terminal 31 but not on the side of the piezoelectric body 2 (Examples 9 to 12)
And the shift amount of the resonance frequency (Δf) and the shift amount of the CI value (ΔCI) after leaving at 125 ° C. for 1000 hours. The quartz oscillator was housed in a jig of 600 g and the height was 125 cm. Amount (Δf) of resonance frequency after 100 times of falling from
The value shift amount (ΔCI) was measured. In addition, the number of peeled terminals from the piezoelectric body (peeling occurrence rate) among the 100 samples was also evaluated.

As a comparative example, a gold layer Au or a silver layer Ag was formed on the piezoelectric body 02 side while the internal terminals 3 were formed.
The gold layer Au, silver layer Ag or nickel layer Ni
Was formed, and samples (Comparative Examples 1 to 6) in which the thiol attachment treatment was not performed on either side were produced.

As a result, as can be seen from Table 1, in the drop test, in Examples 1 to 8 of the present invention, the number of peeling of the internal terminal 31 from the piezoelectric body 2 (peeling occurrence rate) was 0. On the other hand, among the comparative examples, the gold layer Au or the silver layer Ag was used.
In Comparative Examples 1 to 4 in which the electrical characteristics are improved by forming the above, the number of peeling of the internal terminal 31 from the piezoelectric body 2 (peeling occurrence rate) is as many as 5 to 16. Also, in Comparative Examples 5 and 6, in which the nickel layer Ni was formed on the internal terminal 31, the number of the internal terminals 31 peeled from the piezoelectric body 2 (peeling occurrence rate) was one or three. Therefore, according to the present invention, the piezoelectric body 2 and the internal terminal 3
It was confirmed that the mechanical strength of the joint portion with No. 1 was significantly improved.

Further, as can be seen from Table 1, in Examples 9 to 12 of the present invention, the number of peeling of the internal terminals 31 from the piezoelectric body 2 (peeling occurrence rate) is 2 to 14, but it corresponds. When compared with the incidence rates in Comparative Examples 1 to 4, there is a tendency to be small. Therefore, the case where the thiol attachment processing is performed only on the internal terminal 31 side and not performed on the piezoelectric body 2 side (Examples 9 to 9)
Even in the case of 12), it can be seen that the mechanical strength is improved as compared with the case where no thiol attachment treatment is performed.

Also, the shift amount of the resonance frequency (Δf) and the shift amount of the CI value (ΔCI) before and after the drop test can be suppressed to a small value by applying the present invention.

Therefore, with regard to the mechanical strength (drop test), the samples (Examples 1 to 4) in which the thiol attachment treatment was performed on both the piezoelectric body 2 side and the internal terminal 31 side were the most excellent. And a sample in which the thiol attachment process is performed only on the piezoelectric body 2 side and is not performed on the internal terminal 31 side (Examples 5 to 5).
8) Samples in which thiol attachment processing is performed only on the internal terminal 31 side and not performed on the piezoelectric body 2 side (Examples 9 to 12)
It can be said that the effect decreases in the order of. In addition, the combination of the silver layer Ag and the nickel layer Ni was not found between the samples (Comparative Examples 1 to 6) in which the thiol attachment treatment was not performed on either the piezoelectric body 2 side or the internal terminal 31 side. The mechanical strength is highest, and thereafter, the mechanical strength tends to decrease in the order of the combination of the gold layer Au and the silver layer Ag and the combination of the gold layer Au and the gold layer Au.

Further, regarding the stability of the electrical characteristics (standing test), the influence of the materials of the piezoelectric body 2 and the internal terminals 31 is dominant, and the combination of the gold layer Au and the gold layer Au is most excellent. The combination of the gold layer Au and the silver layer Ag and the combination of the silver layer Ag and the nickel layer Ni decrease in this order. It should be noted that the effect of the thiol attachment treatment can be slightly confirmed with respect to the stability of the electrical characteristics.

[0045]

As described above, in the piezoelectric element and the method of manufacturing the same according to the present invention, the thiol-treated film is formed on the surface of the noble metal layer made of gold or silver which covers the mounting portion and the terminals of the piezoelectric body. Therefore, the mounting portion of the piezoelectric body and the terminal can be joined with a high mechanical strength by the conductive adhesive. Therefore, it is possible to reduce the bonding area between the mounting portion of the piezoelectric body and the terminal, and to reduce the size and thickness of the piezoelectric element. Further, even if the surfaces of the mount portion and the terminals of the piezoelectric body are covered with silver or gold, the mechanical strength of the joint does not decrease, so that the reliability in terms of electrical characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a piezoelectric element.

2A is a perspective view of a piezoelectric body on which an electrode film is formed as viewed from one arm end, FIG. 2B is a perspective view of the piezoelectric body viewed from the other arm end, and FIG. It is the side view seen from.

FIG. 3 is an enlarged cross-sectional view showing a joint structure between a mount portion and an internal terminal in a crystal unit to which the present invention is applied.

FIG. 4 is a process chart until an electrode film or the like is formed on a piezoelectric body in a method for manufacturing a piezoelectric element to which the present invention is applied.

FIGS. 5A and 5B are an explanatory diagram showing a state of a thiol attachment process and an explanatory diagram showing a state of a rinsing process in a method of manufacturing a piezoelectric element to which the present invention is applied.

FIG. 6 is a process drawing after an electrode film and the like are formed on a piezoelectric body in a method for manufacturing a piezoelectric element to which the present invention is applied.

FIG. 7 is a perspective view showing the overall configuration of another type of piezoelectric element different from the piezoelectric element shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz crystal resonator (piezoelectric element) 21 Base part of piezoelectric element 22, 23 Arm part of piezoelectric element 30 Terminal 31 Internal terminal of terminal 35 Case 41, 42 Electrode film 50 Conductive adhesive 51, 52 Mounting part 60, 61 Thiol treatment Membrane L1 Treatment liquid L2 Alcohol for rinsing

Claims (5)

[Claims] 1. A piezoelectric element having a piezoelectric body and a terminal joined to a mount portion of the piezoelectric body by a conductive adhesive, wherein a surface of the mount portion and the terminal of the piezoelectric body is made of gold or silver. A piezoelectric element covered with a noble metal layer, and a thiol-treated film is formed on a surface of the noble metal layer of at least one of the mount portion and the terminal of the piezoelectric body. 2. The piezoelectric element according to claim 1, wherein a thiol-treated film is formed on the surface of the noble metal layer on both the mount portion and the terminal of the piezoelectric body. 3. A method for manufacturing a piezoelectric element having a piezoelectric body and a terminal joined to a mount of the piezoelectric body by a conductive adhesive, wherein the surface of the mount of the piezoelectric body and the surface of the terminal are made of gold or silver. After being covered with a noble metal layer consisting of, the piezoelectric body is bonded to the terminal and the terminal by a conductive adhesive applied to at least one of the mount portion and the terminal of the piezoelectric body. A thiol-treated film is formed on the surface of the noble metal layer of at least one of the mount portion and the terminal. 4. The method for manufacturing a piezoelectric element according to claim 3, wherein the formation of the thiol-treated film is performed on the surface of the noble metal layer on both the mounting portion of the piezoelectric body and the terminal. 5. The thiol-treated film according to claim 3, wherein the thiol-treated film is formed by bringing a treatment liquid obtained by diluting thiol with a solvent into contact with the surface of the noble metal layer on which the thiol-treated film is to be formed. A method for forming a piezoelectric element, comprising: