JP2011229100A - Vibration piece and vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration piece which has superior temperature characteristics.SOLUTION: The vibration piece 10 includes a vibrator 11 having a base 12 and vibration arms 14a, 14b extended from the base 12 in parallel and vibrating in a bending mode, and Cr layers 24a, 24b provided on a surface of the vibrator 11 and having such a Young's modulus or a coefficient of thermal expansion that a temperature as an inflection point is within the operational temperature range of the vibrator 11, and a temperature characteristic curve of frequency deviation is generated by adding a frequency deviation due to a peak temperature of the temperature characteristic curve and a frequency deviation due to a film thickness H of the Cr layers 24a, 24b. Consequently, the vibration piece 10 has the superior frequency temperature characteristics in the operational temperature range.

Description

  The present invention relates to a vibrating piece and a vibrator having the vibrating piece.

  Conventionally, a resonator element made of quartz having frequency temperature dependency uses Cr as an underlayer, and the frequency deviation associated with temperature change is achieved by setting the thickness of the Cr layer to a range of 0.07 μm to 0.3 μm. It is known that this change can be reduced (see, for example, Patent Document 1).

JP 2005-136499 A

  In Patent Document 1, the temperature range in which the difference in frequency deviation due to temperature change can be reduced is narrow. For example, in the wide temperature range where the operating temperature range is −40 ° C. to 100 ° C., the effect of forming the Cr layer is obtained. There is a problem that it cannot be obtained sufficiently.

  In Patent Document 1 described above, the apex temperature of the temperature characteristic curve of frequency deviation is set to 25 ° C. This is a conventional general apex temperature. In such a case, the difference in frequency deviation due to temperature change is small on the low temperature side where the influence of the Cr layer is large, but on the high temperature side where the influence of the Cr layer is small, It is difficult to improve the frequency deviation difference.

  The present invention provides a resonator element capable of obtaining better frequency temperature characteristics than the conventional one and a vibrator on which the resonator element is mounted, and can be realized as the following forms or application examples. .

  Application Example 1 A resonator element according to this application example includes a vibrating body having a base portion and a plurality of vibrating arms that extend in parallel from the base portion and perform flexural vibration in opposite phases, and the surface of the vibrating body. Provided with a temperature at which the Young's modulus or the coefficient of thermal expansion becomes an inflection point, and the temperature at which the inflection point is within the operating temperature range of the vibrator, and the temperature characteristics of the vibrator A frequency deviation temperature characteristic curve is generated by adding the frequency deviation depending on the vertex temperature of the curve and the frequency deviation depending on the film thickness of the underlayer.

According to this application example, by combining the effect of setting the film thickness of the underlayer to an appropriate range on the lower temperature side than the temperature that becomes the inflection point, and the effect of increasing the vertex temperature on the high temperature side, The frequency temperature characteristic can be improved.
The apex temperature can be changed by changing the cut angle of the crystal. If the apex temperature is changed higher, the frequency temperature characteristic on the high temperature side can be improved.

  Application Example 2 In the resonator element according to the application example described above, it is preferable that the base layer is made of Cr or an Au—Cr alloy.

  The temperature at which the aforementioned Young's modulus or thermal expansion coefficient becomes an inflection point is the Neel temperature. The Neel temperature is a temperature at which the antiferromagnetic state transitions to the paramagnetic state, and an inflection point (or extreme value) of Young's modulus or thermal expansion coefficient appears. And since alloys, such as Cr or Au-Cr, have a Neel temperature in the operating temperature range (for example, the range of -40 degreeC-100 degreeC) of a vibration piece, it can improve a frequency temperature characteristic.

  Moreover, since alloys such as Cr and Au—Cr have been used as contact metals for quartz used as a vibrating body in the past, adhesion with the quartz is good and the burden on the manufacturing process is small.

  Application Example 3 In the resonator element according to the application example described above, the vibrating body is made of crystal, the frequency deviation of the vibrating body is expressed as Δf0, and the base layer in the operating temperature range below the temperature that becomes the inflection point. When the frequency deviation depending on the film thickness is expressed as Δf1, it is preferable that the frequency deviation Δf3 of the vibrating body in the operating temperature range equal to or lower than the temperature at which the inflection point is expressed by Δf3 = Δf0 + Δf1.

  Application Example 4 In the resonator element according to the application example, the frequency deviation of the vibrating body is expressed as Δf0, and the frequency deviation depending on the film thickness of the base layer in the operating temperature range equal to or higher than the temperature that becomes the inflection point. When expressed as Δf2, it is preferable that the frequency deviation Δf4 of the vibrating arm in the operating temperature range equal to or higher than the temperature that becomes the inflection point is expressed by Δf4 = Δf0 + Δf2.

  In this way, by combining the effect of setting the thickness of the underlayer to an appropriate range on both the low temperature side and the high temperature side of the temperature that becomes the inflection point, and the effect of increasing the vertex temperature, The frequency temperature characteristic can be improved.

Application Example 5 In the resonator element according to the application example, when the film thickness of the base layer is H, the allowable range of the film thickness is ΔH, and the vertex temperature is Tp, the film thickness H is
It is preferable that H = −1.25 × 10 ¹ × Tp ² + 25.2 × Tp + 424 + ΔH.

  If the film thickness of the underlayer is set by the above formula, the frequency temperature characteristic on the low temperature side can be improved. In addition, good frequency temperature characteristics can be obtained even when the variation range of the film thickness is taken into consideration.

  Application Example 6 A vibrator according to this application example is characterized in that the resonator element described in each application example is mounted inside a package.

  The above-described vibrating piece is mounted in a package formed of, for example, ceramic. Therefore, it is possible to realize a highly reliable vibrator capable of obtaining good frequency temperature characteristics in a wide temperature range.

Note that the inside of the package is preferably in a vacuum state, and the vibration piece is vibrated in a vacuum environment, so that more stable vibration can be maintained over a long period of time.
In addition, by being housed in the package, it is easy to handle and the resonator element can be protected from the external environment such as humidity.

The resonator element according to Embodiment 1 is shown, (a) is a plan view, and (b) is a cross-sectional view showing the AA cut surface of (a). The temperature characteristic curve which shows the temperature characteristic of the frequency deviation on the basis of 25 degreeC in case of cut angle 1 degree 30 '. The temperature characteristic curve which shows the temperature characteristic of the frequency deviation on the basis of 25 degreeC in case of cut angle 5 degrees 20 '. The temperature characteristic curve which shows the temperature characteristic of the frequency deviation on the basis of 25 degreeC when changing a cut angle and changing vertex temperature by making Cr film thickness 500mm. The temperature characteristic curve which shows the temperature characteristic of the frequency deviation on the basis of 25 degreeC in the case of Cr film thickness = 1500mm. The temperature characteristic curve which shows the temperature characteristic of the frequency deviation on the basis of 25 degreeC in case Cr film thickness = 2500mm. The graph which shows the relationship between Cr film thickness H from which frequency deviation will be 170 ppm, and vertex temperature Tp. The graph which shows the relationship between Cr film thickness H calculated using Numerical formula (8) and Numerical formula (9), and vertex temperature Tp. A temperature characteristic curve representing the apex temperature Tp and the Cr film thickness H at which the temperature characteristic becomes almost flat at −15 ° C. as parameters. Sectional drawing which shows schematic structure of a vibrator | oscillator.

Embodiments of the present invention will be described below with reference to the drawings. 1 and 10 are schematic diagrams in which the vertical and horizontal scales of members or portions are different from actual ones for convenience of illustration.
(Embodiment 1)

  1A and 1B show a resonator element according to the first embodiment, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along the line AA in FIG. Note that the resonator element 10 according to the present embodiment will be described by taking quartz as an example of an element element that constitutes a vibration body having frequency temperature dependency. Further, the vibration mode will be described by exemplifying a tuning fork type having a bending vibration of opposite phase as a main vibration.

  1A and 1B, the resonator element 10 includes a vibrating body 11 and a metal film formed on the vibrating body 11. The vibrating body 11 is a so-called tuning fork type vibrating body that is formed of quartz crystal that exhibits a piezoelectric effect, and includes a base portion 12 and vibrating arms 14 a and 14 b that extend from the base portion 12 in parallel to the Y-axis direction. The vibrating body 11 is cut from a single crystal of crystal at a predetermined cut angle so that the X axis is an electric axis, the Y axis is a mechanical axis, and the Z axis is an optical axis.

  Grooves 25a and 25b are formed in the central portions in the width direction of the vibrating arms 14a and 14b (see FIG. 1B). The width of the grooves 25a and 25b is 50% to 90% of the width of the vibrating arms 14a and 14b, and the depth is 30% to 49% of the thickness of the vibrating arms 14a and 14b.

  The metal film includes base layers 24a and 24b formed in close contact with the inner surfaces of the grooves 25a and 25b and the outer side surfaces of the vibrating arms 14a and 14b, and an electrode layer formed in close contact with the surfaces of the base layers 24a and 24b and serving as a surface layer. Consists of.

  The electrode layer includes excitation electrodes 18a and 18b for exciting vibration, input / output electrodes 22a and 22b for inputting and outputting drive signals and detection signals, excitation electrodes 18a and 18b, and input / output electrodes 22a and 22b. , Are connected to extraction electrodes 20a and 20b. Since the base layers 24a and 24b are made of an alloy such as Cr or Au—Cr, the base layers 24a and 24b are hereinafter referred to as Cr layers 24a and 24b. The excitation electrodes 18a and 18b and the extraction electrodes 20a and 20b are made of Au.

  Cr is employed because it has good adhesion to the quartz used as the vibrator 11 and is excellent as a contact metal. Further, gold (Au) has a feature that it has an extremely low electric resistance, is stable, is hardly affected by oxidation, and has little property change due to deterioration over time.

  In such a vibrating piece 10, the vibration arms 14 a and 14 b are flexibly vibrated in the X-axis direction with the base portion 12 as a fixed end by inputting an external excitation signal.

Next, the relationship between the temperature characteristics of the cut angle and the frequency deviation will be described.
FIG. 2 is a temperature characteristic curve showing a frequency characteristic of a frequency deviation based on 25 ° C. when the cut angle is 1 ° 30 ′ and FIG. 3 is a cut angle of 5 ° 20 ′. In addition, the Cr film thickness is set to 500 mm, the Au film thickness is set to 500 mm, and how the frequency temperature characteristic as the vibrating piece 10 changes depending on the cut angle is obtained by experiments. In both figures, the horizontal axis represents temperature [° C.] and the vertical axis represents frequency deviation Δf [ppm].

  In the case of a cut angle of 1 ° 30 ′, as shown in FIG. 2, the peak temperature of the temperature characteristic curve is 25 ° C., and the fluctuation amount of the frequency deviation is small on the temperature side lower than the peak temperature. It can be seen that the fluctuation amount of the frequency deviation is larger on the higher temperature side than on the lower temperature side.

  When the cut angle is 5 ° 20 ′, as shown in FIG. 3, the peak temperature of the temperature characteristic curve is approximately 50 ° C., and the fluctuation amount of the frequency deviation is large on the temperature side lower than the peak temperature. It can be seen that the fluctuation amount of the frequency deviation is smaller on the temperature side higher than the apex temperature than on the low temperature side.

  Therefore, comparing FIG. 2 and FIG. 3, the vertex temperature changes by changing the cut angle of the crystal, and the fluctuation amount of the frequency deviation is adjusted between the high temperature side and the low temperature side with respect to the vertex temperature. You can see that Thus, it has been found that the frequency temperature characteristic is further improved by changing the vertex temperature and the thickness of the Cr layers 24a and 24b, and the formulating this will be described.

  First, the variation due to the temperature change of the frequency deviation of the crystal itself that does not consider the Cr film thickness is formulated. Here, the apex temperature of the crystal is represented by Tp [° C.], the temperature is represented by T [° C.], and the frequency deviation is represented by Δf0 [ppm].

Δf0 = A1 × T ³ + A2 × T ² + A3 × T + A4 (1)
In addition, A1, A2, A3, and A4 of each term of Formula (1) are each represented by the following formula.
A1 = 8.75 × 10 ⁻⁵
A2 = (3.00 × 10 ⁻⁴ ) × Tp−0.0347 × 10 ⁻²
A3 = (− 3 × 10 ⁻⁴ ) × Tp ² + 6.96 × 10 ⁻² × Tp−4.60 × 10 ⁻³
A4 = 7.20 × 10 ⁻³ × Tp ² −1.96 × Tp + 24.4

The frequency deviation calculated by the above formula is shown in FIG.
FIG. 4 is a temperature characteristic curve showing the temperature characteristics of the frequency deviation when the Cr film thickness is 500 mm and the cut angle is changed to change the vertex temperature. The horizontal axis represents the temperature T [° C.], the vertical axis represents the frequency deviation [ppm], and the apex temperature was changed every 10 ° C. within the range of 15 ° C. to 85 ° C. as parameters. Actually, the peak temperature that can be changed by the cut angle is about 60 ° C.

  As shown in FIG. 4, it can be seen that the higher the vertex temperature, the smaller the fluctuation amount of the frequency deviation on the higher temperature side than the vertex temperature, and the larger the fluctuation amount of the frequency deviation on the lower temperature side than the vertex temperature. Under these conditions, it can be seen that the standard deviation of 170 ppm according to the prior art is not improved. This is considered that the combination of the vertex temperature Tp and the Cr film thickness was not appropriate.

  Therefore, based on the above result, the influence of the Cr film thickness is divided into two temperature ranges of −40 ° C. to 10 ° C. and 10 ° C. to 100 ° C., and is formulated. First, the temperature range of −40 ° C. to 10 ° C. will be described. In addition, the Cr film thickness is H, and the frequency deviation of each temperature in the temperature range of −40 ° C. to 10 ° C. is represented by Δf1.

Δf1 = (2.40 × 10 ⁻³ × H + 4.00 × 10 ⁻² ) × T + 5.78 × 10 ⁻² × H-41.0 (2)

  Next, the temperature range of + 10 ° C. to 100 ° C. will be described. Note that the frequency deviation of each temperature in this temperature range is represented by Δf2.

Δf2 = B1 × H ² + B2 × H + B3 (3)
Here, B1, B2, and B3 of each term of Formula (3) are each expressed by the following formulas.
B1 = 1.17 × 10 ⁻⁹ × T ² + 9.74 × 10 ⁻⁷ × T + 5.15 × 10 ⁻³
B2 = −2.23 × 10 ⁻⁷ × T ² + 4.75 × 10 ⁻⁴ × T−1.24
B3 = 3.68 × 10 ⁻⁶ × T2−6.97 × 10 ⁻⁴ +13.7

Therefore, the frequency deviation Δf1 (formula (2)) and Δf2 due to the Cr film thickness H in two temperature ranges of −40 ° C. to 10 ° C. and 10 ° C. to 100 ° C. (Formula (3)) is added to form a formula.
The frequency deviation Δf3 in the temperature range of −40 ° C. to 10 ° C. is expressed by the following equation.

  Δf3 = Δf0 + Δf1 (4)

  The frequency deviation Δf4 in the temperature range of + 10 ° C. to 100 ° C. is expressed by the following equation.

  Δf4 = Δf0 + Δf2 (5)

Here, when Cr film thickness H = 1500 mm, when Cr film thickness H = 2500 mm, the frequency deviation in the temperature range of −40 ° C. to 100 ° C. calculated using Equation (4) and Equation (5). FIG. 5 and FIG. 6 illustrate the measured values with reference to 25.degree. The apex temperature Tp was 55 ° C.
FIG. 5 is a temperature characteristic curve based on 25 ° C. showing the temperature characteristic of the frequency deviation when the Cr film thickness H = 1500 mm. In FIG. 5, the frequency deviation has a temperature characteristic curve in which two curves are combined at 10 ° C., and the fluctuation amount of the frequency deviation tends to be small in the range of 10 ° C. or less and large in the range of + 10 ° C. or more. You can see that That is, the temperature characteristic curve has an inflection point at 10 ° C.

  FIG. 6 is a temperature characteristic curve showing the temperature characteristic of the frequency deviation when the Cr film thickness is 2500 mm. In FIG. 6, the frequency deviation of the resonator element 10 has a temperature characteristic curve having an inflection point in which two curves are combined at 10 ° C., and the fluctuation amount of the frequency deviation is large in the range of 10 ° C. or less. It can be seen that the above range tends to be small.

  5 and 6, the calculated value and the actually measured value are compared. However, since the calculated value and the actually measured value are almost the same, it is determined that the above-described mathematical formula is valid. it can.

  Further, when comparing the temperature characteristic curves of FIG. 2 to FIG. 6, the frequency deviation has a ratio that depends on the Cr film thickness H on the high temperature side and on the Cr film thickness H on the low temperature side. It can be read that it is expensive. From this, the influence of the Cr film thickness H on the frequency deviation will be described.

  Here, the resonance frequency of the resonator element 10 is calculated from factors such as the length, width, and thickness of the vibrating arms 14 a and 14 b in the vibrating body 11, the density of the substance constituting the vibrating body 11, boundary conditions, and the elastic constant. can do. As an element that varies due to a change in the thickness of the metal film 16 formed on the vibrating arms 14a and 14b, an elastic constant can be given. Among the elements constituting the elastic constant, Young's modulus and thermal expansion coefficient exist as elements that vary with temperature changes. For this reason, it is considered that the temperature dependence of the resonance frequency of the resonator element 10 is also brought about by a change in Young's modulus and thermal expansion coefficient.

  If the Young's modulus and the thermal expansion coefficient are proportional to the temperature change, the inflection point does not appear in the temperature characteristic curve in this way, so that the Neel temperature is inherent in the operating temperature range of the resonator element 10 in the Cr film. It can be said that.

  Here, the Neel temperature refers to the temperature at which the antiferromagnetic material transitions to the paramagnetic state. Note that antiferromagnetism is a property of magnetism in which adjacent spins are aligned in opposite directions and have no magnetic moment as a whole. Paramagnetism is magnetism that does not have magnetization when there is no external magnetic field and magnetizes weakly in that direction when a magnetic field is applied. That is, it can be said that the rapid change in Young's modulus occurs with the state transition of the magnetic material.

  Antiferromagnets are known to cause large volume changes due to the disappearance of magnetic moment by undergoing transition from paramagnetic material at the Neel temperature. With temperature, it can be said that the coefficient of thermal expansion also changes.

  It is known that the Neel temperature changes with changes in compressive stress and extensional stress due to differences in film thickness. Specifically, the Neel temperature of Cr thinned compared with solid Cr shifts to the low temperature side within a range of several tens of degrees Celsius. When the Cr film thickness H is increased, the Neel temperature is shifted to a higher temperature side, and when the Cr film thickness H is decreased, the Neel temperature is shifted to a lower temperature side. As described above, since the change in Young's modulus is larger on the low temperature side than the Neel temperature, a mathematical formula that brings the frequency-temperature characteristics on the low temperature side closer to flatness is derived.

  Therefore, in order to derive the condition of the apex temperature at which the variation in frequency deviation is the smallest on the low temperature side and the Cr film thickness H, Equation (4) is differentiated by the temperature T, and −40 ° C. to 10 ° C. Substituting −15 ° C., which is an intermediate temperature, into T, Equation (6) for calculating the Cr film thickness H is derived.

  The reason for selecting −15 ° C. is that if the temperature characteristic curve becomes nearly flat at −15 ° C. from the temperature characteristic curves of FIGS. 5 and 6, the temperature characteristic curve is flat on the low temperature side from the inflection point of the temperature characteristic curve. This is because it has been determined that temperature characteristics can be obtained. Further, the apex temperature Tp is limited to a range of + 35 ° C. to + 85 ° C. in which the frequency deviation is smaller than the frequency deviation of 170 ppm in the temperature range of −40 ° C. to + 100 ° C. of Patent Document 1 described above.

H = −1.25 × 10 ⁻¹ × Tp ² + 25.2 × Tp + 424 (6)
The calculation results using the formula (6) are shown in Table 1 and FIG.

  FIG. 7 is a graph showing the relationship between the Cr film thickness H at which the frequency deviation is 170 ppm and the apex temperature Tp. The abscissa represents the apex temperature Tp [° C.], and the ordinate represents the Cr film thickness H [Å]. From FIG. 7, when the vertex temperature Tp is in the range of 35 ° C. to 85 ° C. and the Cr film thickness H is in the range of 1155 mm to 1667 mm, an area where the standard deviation is smaller than 170 ppm is obtained by setting the vertex temperature Tp and Cr film thickness H. It is done.

  However, as shown in Table 1 and FIG. 7, an appropriate combination of the appropriate apex temperature Tp and the Cr film thickness H is one point at a time, and the range of the Cr film thickness H becomes narrow, so that it corresponds to the apex temperature Tp. Then, a calculation formula is derived by adding ΔH to the allowable range for the Cr film thickness H at which the temperature characteristic approaches flat and the frequency deviation becomes 170 ppm, and is added to Formula (6).

H = −1.25 × 10 ⁻¹ × Tp ² + 25.2 × Tp + 424 + ΔH (7)

  Then, a calculation formula for obtaining the allowable range ΔH is derived. The allowable range ΔH has a direction of increasing thickness (represented as ΔH (+)) and a direction of decreasing thickness (represented as ΔH (−)), and is therefore divided into equations.

ΔH (+) = − 2.31 × 10 ⁻¹ × Tp ² + 37.7 × Tp + 352 (8)

ΔH (−) = − 1.91 × 10 ⁻² × Tp ² + 12.8 × Tp + 496 (9)

  The results of calculating the Cr film thickness using the above formula (8) and formula (9) are shown in Table 2 and FIG.

  FIG. 8 is a graph showing the relationship between the Cr film thickness H calculated using Equation (8) and Equation (9) and the apex temperature Tp. The abscissa represents the apex temperature Tp [° C.], the ordinate represents the Cr film thickness H [Å], the upper graph represents H + ΔH (+), the lower graph represents H + ΔH (−), and the middle graph represents the Cr film thickness H. Represents the median. From FIG. 8, it is shown that the Cr film thickness H allows the variation in the range calculated by the formula (8) and the formula (9) with respect to the vertex temperature Tp. That is, it is possible to find a range of the Cr film thickness H in which the frequency deviation is within 170 ppm with respect to the vertex temperature Tp including variation.

  For example, when the apex temperature Tp is 35 ° C., a frequency deviation of 170 ppm is obtained when the Cr film thickness H is in the range of 920 to 1390 °.

Next, temperature characteristics under the conditions of the vertex temperature Tp and the Cr film thickness H will be described using Equation (6).
FIG. 9 is a temperature characteristic curve that represents the apex temperature Tp and the Cr film thickness H at which the temperature characteristic becomes substantially flat at −15 ° C. as parameters. The horizontal axis represents temperature T [° C.] and the vertical axis represents frequency deviation [ppm]. FIG. 9 represents a temperature characteristic curve of a combination of the optimum vertex temperature Tp and the optimum Cr film thickness H with respect to this vertex temperature Tp.

As shown in FIG. 9, the frequency deviation is 170 ppm or less in the operating temperature range of −40 ° C. to + 100 ° C. It can also be seen that the temperature characteristic curve is almost flat at 10 ° C. or lower.
Further, the temperature characteristic is remarkably improved as compared with the frequency deviation of the conventional tuning fork vibrating piece without means for improving the temperature characteristic shown in the figure.

  Therefore, according to the present embodiment, the frequency deviation Δf0 due to the influence of the apex temperature Tp and the frequency deviations Δf1 and Δf2 due to the influence of the Cr film thickness H are respectively expressed as mathematical formulas, and Δf0 and Δf1, and Δf0 and Δf2 are added together. Thus, the frequency temperature characteristic can be improved.

  Further, since the frequency deviation depends on the apex temperature Tp on the high temperature side and largely depends on the Cr film thickness H on the low temperature side, Δf1 and Δf2 are respectively divided into the low temperature side and the high temperature side of the inflection point. Therefore, good frequency temperature characteristics can be obtained within a wider operating temperature range than the prior art.

  In particular, the temperature characteristic curve on the low temperature side, which was difficult with the prior art, can be made almost flat, and a resonator element having excellent frequency temperature characteristics can be realized.

Moreover, since Cr is used as the underlayer and the Neel temperature of Cr is in the operating temperature range (−40 ° C. to 100 ° C.) of the resonator element 10, an extreme value or inflection point of Young's modulus appears in the operating temperature range. Thus, the frequency temperature characteristics can be improved reliably.
In addition, since Cr and Au—Cr alloy have been conventionally used as a contact metal for quartz, the adhesion to the quartz is good and the burden in the manufacturing process is small.

In the above-described embodiment, Cr or an alloy mainly composed of Cr is used as an example of the metal constituting the temperature characteristic correction unit, but the Curie temperature or the Neel temperature is within the operating temperature range of the vibrator. For example, other members may be used.
(Vibrator)

Next, an example of a vibrator using the above-described vibrating piece 10 will be described with reference to the drawings.
FIG. 10 is a cross-sectional view showing a schematic configuration of the vibrator. The vibrator 100 mainly includes the above-described vibration piece 10, a package base 110 that accommodates the vibration piece 10, and a lid 120 that seals an opening of the package base 110.

  The package base 110 is a box body obtained by laminating and firing ceramic green sheets and the like, and an internal mounting electrode 112 for mounting the resonator element 10 is formed inside a cavity formed in a concave shape. External mounting terminals 114 are formed on the bottom surface outside the package base 110. The external mounting terminal 114 is electrically connected to the internal mounting electrode 112 through a not-shown through hole or the like.

  In the present embodiment, the lid 120 has a flat plate shape. As the constituent member, a metal or glass is often employed. Whichever member is employed, it is desirable to employ a member whose linear expansion coefficient approximates that of the component of the package base 110.

  The resonator element 10 is mounted in the package base 110 configured as described above. A conductive adhesive 116 is used for mounting the resonator element 10. A conductive adhesive 116 is applied to the internal mounting electrode 112, and the input / output electrodes of the resonator element 10 are joined to the applied conductive adhesive 116.

  When the opening of the package base 110 on which the resonator element 10 is mounted is sealed, the lid 120 is bonded via the bonding member 118. The joining member 118 differs depending on the members constituting the lid 120. For example, when the lid 120 is a metal, a seal ring made of a low melting point metal is used for the joining member 118. On the other hand, when the lid 120 is made of glass, low-melting glass is used for the bonding member 118.

  A space formed by the package base 110 and the lid 120 is hermetically sealed so as to maintain a reduced pressure state or a vacuum state.

  In the vibrator 100 configured as described above, the resonator element is excited by a driving signal from the outside via the external mounting terminal 114, and oscillates (resonates) at a predetermined frequency (for example, 32 kHz).

  As described above, in the resonator 100, the resonator element 10 having the above-described vertex temperature Tp and Cr film thickness H has improved frequency temperature characteristics, and the resonator 100 has high reliability in a wide temperature range. Can do.

  Further, the vibrating piece 10 is housed in a package, and can be maintained in a package in a vacuum environment to maintain a more stable vibration over a long period of time. Further, by being housed in the package, it is easy to handle, and the resonator element can be protected from the external environment such as humidity.

  DESCRIPTION OF SYMBOLS 10 ... Vibrating piece, 11 ... Vibrating body, 12 ... Base part, 14a, 14b ... Vibrating arm, 24a, 24b ... Cr layer.

Claims (6)

A vibrating body having a base and a plurality of vibrating arms extending in parallel from the base and performing flexural vibrations in opposite phases;
An underlayer provided on the surface of the vibrating body, having a temperature at which the Young's modulus or thermal expansion coefficient becomes an inflection point, and the temperature at which the inflection point is within an operating temperature range of the vibrating body;
Have
A vibration piece characterized by adding a frequency deviation depending on a vertex temperature of a temperature characteristic curve of the vibrating body and a frequency deviation depending on a film thickness of the underlayer to generate a temperature characteristic curve of the frequency deviation. . The resonator element according to claim 1,
The resonator element, wherein the underlayer is made of Cr or an Au-Cr alloy. In the resonator element according to claim 1 or 2,
The vibrating body is made of crystal,
The frequency deviation of the vibrating body is expressed as Δf0,
When the frequency deviation depending on the film thickness of the underlayer in the operating temperature range below the temperature that becomes the inflection point is expressed as Δf1,
The frequency deviation Δf3 of the vibrating body in the operating temperature range below the temperature that becomes the inflection point is
A vibrating piece characterized by Δf3 = Δf0 + Δf1. In the resonator element according to any one of claims 1 and 3,
The frequency deviation of the vibrating body is expressed as Δf0,
When the frequency deviation depending on the film thickness of the underlayer in the operating temperature range equal to or higher than the temperature that becomes the inflection point is expressed as Δf2,
The frequency deviation Δf4 of the vibrating arm in the operating temperature range equal to or higher than the temperature that becomes the inflection point is
A vibrating piece characterized by Δf4 = Δf0 + Δf2. In the resonator element according to any one of claims 1 to 4,
When the thickness of the underlayer is H, the allowable range of the thickness is ΔH, and the apex temperature is Tp, the thickness H is
H = −1.25 × 10 ¹ × Tp ² + 25.2 × Tp + 424 + ΔH
It is represented by the vibration piece characterized by.   A vibrator, wherein the resonator element according to claim 1 is mounted inside a package.

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