JP2010103963A - Crystal resonator element and crystal resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AT-cut crystal vibrator in which equivalent parallel capacitor C0 does not increase while reducing a crystal impedance CI by connecting a lead-out electrode to an excitation electrode in the shape of a sector, in order to improve balancing of the crystal impedance CI and the equivalent parallel capacitor C0. <P>SOLUTION: The crystal vibrator (10) is constituted such that: the lead-out electrode (13) is connected to the excitation electrode (12) in the shape of a sector; and the crystal impedance CI is reduced without increasing the equivalent parallel capacitor C0 since the center angle of the angle of the sector is set within the range of 90 to 180 degrees. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a quartz crystal resonator element that particularly improves vibration characteristics.

  The quartz crystal resonator element is known as a frequency control element, and is incorporated as a frequency and time reference source in an oscillator of various electronic devices. In recent years, there has been a crystal resonator element whose frequency has been increased to, for example, the 600 MHz band due to the rise of optical communication or the like, and the thickness of the vibration region has been reduced by etching.

  The crystal vibrating piece 70 disclosed in Patent Document 1 is composed of a rectangular crystal piece 71 having an AT cut. As shown in FIG. 7, a pair of excitation electrodes 72 provided opposite to each other are formed at the center of the crystal piece 71. In addition, an extraction electrode 73 extends from the pair of excitation electrodes 72 to both ends in opposite directions, and the extraction electrode 73 is widely formed in the vicinity of both ends of the crystal piece 71. The connection area CA is a connection portion between the excitation electrode 72 and the extraction electrode 73, and the arrow AR indicates the supply of electric energy.

Japanese Patent Laid-Open No. 2004-40693

  However, the conventional crystal resonator element has a problem that the crystal impedance CI is basically increased due to the reduction of the outer dimension of the crystal element accompanying the miniaturization. For example, as shown in Patent Document 1, when the excitation electrode becomes smaller, the connection region between the excitation electrode and the extraction electrode becomes shorter. For this reason, there is a problem that the electrical conduction resistance between the excitation electrode and the extraction electrode becomes large, and sufficient electrical energy cannot be supplied to the excitation electrode as indicated by an arrow AR in FIG. In addition, since the width of the extraction electrode itself is small, there is a problem that the crystal impedance CI is increased by increasing the conduction resistance.

  In addition, there is a limit to reducing the crystal impedance CI by increasing the connection region between the extraction electrode and the excitation electrode. That is, it is assumed that the crystal impedance CI can be reduced by connecting each extraction electrode in a connection region longer than a half circumference of the excitation electrode and supplying electric energy from the connection region. However, in this case, since a pair of extraction electrodes are overlapped between both main surfaces, there is a problem that the equivalent parallel capacitance C0 increases.

  In order to improve the balance between the crystal impedance CI and the equivalent parallel capacitance C0, the present invention reduces the crystal impedance CI by connecting the extraction electrode to the excitation electrode in a fan shape and at the same time does not increase the equivalent parallel capacitance C0. An object of the present invention is to provide a quartz crystal resonator element of a mold.

A crystal vibrating piece according to a first aspect includes a crystal piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the crystal piece, and a pair of extraction electrodes that respectively extend from the excitation electrode. The extraction electrode of the crystal vibrating piece has a region extending from the vicinity of the center of the excitation electrode into a fan shape having a central angle θ of 90 ° or more and less than 180 °, and the center of the excitation electrode and the center of the extraction electrode Are not aligned with the first direction, and a connecting line extending in a fan shape of the pair of extraction electrodes intersects at both points in the second direction orthogonal to the first direction and around the excitation electrode.
According to such a configuration, the connection region between the excitation electrode and the extraction electrode is a half circumference of the excitation electrode, the extraction electrode is fan-shaped and the area of the extraction electrode is increased, and the extraction electrodes do not overlap each other. As the crystal impedance CI decreases, the equivalent parallel capacitance C0 does not increase. Accordingly, the vibration characteristics of the quartz crystal resonator element are enhanced.

The quartz crystal resonator element according to the second aspect is arranged on a quartz crystal piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the crystal piece, a semicircle portion connected to the excitation electrode, and an outer periphery of the semicircle portion. And a pair of extraction electrodes constituted by a base portion. And the semicircular portion of the extraction electrode of the quartz crystal vibrating piece has the center of the semicircular portion coincident with the center of the excitation electrode, and the inner periphery of the semicircular portion is connected to the half of the excitation electrode. The center of the base portion coincides with the excitation electrode, and has a fan-shaped region having a center angle θ of 90 ° or more and less than 180 °.
According to such a configuration, the connection region between the excitation electrode and the extraction electrode is not only the half circumference of the excitation electrode, but the two semicircular portions surround the excitation electrodes formed on both sides of the crystal piece, respectively. Electrical energy can be supplied from the half circumference of the excitation electrode. In addition, since the extraction electrodes are fan-shaped and the area of the extraction electrodes is increased and the extraction electrodes do not overlap each other, the crystal impedance CI of the extraction electrodes is reduced and the equivalent parallel capacitance C0 is not increased. Accordingly, the vibration characteristics of the quartz crystal resonator element are enhanced.

  The extraction electrode of the crystal vibrating piece of the third aspect is formed by sequentially stacking the first film, the second film, the third film, and the fourth film on both surfaces of the crystal piece, and the excitation electrode is formed of the third film and the fourth film. A film is sequentially formed on both sides of the crystal piece, and the second film and the fourth film include gold (Au).

A crystal vibrating piece according to a fourth aspect includes a crystal piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the crystal piece, and a pair of extraction electrodes that respectively extend from the excitation electrode. The extraction electrode of the quartz crystal vibrating piece has a region extending from the vicinity of the center of the excitation electrode in a fan shape having a center angle θ of 90 ° or more and 180 ° or less, the first film, the second film, the third film, and The fourth film is formed by sequentially stacking on both sides of the crystal piece, the excitation electrode is formed by sequentially stacking the third film and the fourth film on both sides of the crystal piece, and the second film and the fourth film are: Including gold (Au).
According to the 3rd viewpoint and the 4th viewpoint, an extraction electrode becomes thicker and crystal impedance CI can be made smaller. Furthermore, since the second film and the fourth film contain gold (Au), they have high antioxidant and corrosion resistance and low chemical reactivity, and their electrical characteristics are hardly changed even after high temperature operation.

  In the quartz crystal resonator element according to the fifth aspect, the first film and the third film are thinner than the second film and the fourth film.

In the crystal vibrating piece according to the sixth aspect, the second film is thicker than the fourth film.
According to the fifth and sixth aspects, by making the extraction electrode thicker, the crystal impedance CI is further reduced, and the vibration characteristics of the quartz crystal resonator element can be enhanced.
In the quartz crystal resonator element according to the seventh aspect, the pair of excitation electrodes is polygonal or circular.
A crystal resonator according to an eighth aspect includes the crystal resonator element according to the first to eighth aspects and a package for fixing the crystal oscillator piece.

  The AT-cut quartz crystal resonator element according to the present invention has a longer connection area between the excitation electrode and the extraction electrode, and the extraction electrode spreads in a fan shape to increase the area of the extraction electrode, so that the extraction electrodes do not overlap with each other. As CI decreases, the equivalent parallel capacitance C0 does not increase. Therefore, the vibration characteristics of the AT-cut type quartz vibrating piece can be enhanced.

It is sectional drawing of the quartz oscillator which accommodated the AT cut type quartz vibrating piece. It is a top view of the AT cut type | mold crystal vibrating piece which concerns on a 1st Example. It is a top view of the extraction electrode of the AT cut type crystal vibrating piece of the first embodiment. 1 is a cross-sectional view of an AT-cut type crystal vibrating piece. It is a top view of the AT cut type | mold crystal vibrating piece which concerns on a 2nd Example. It is a top view of the extraction electrode of the AT cut type crystal vibrating piece of the second embodiment. It is a top view which shows an example of the prior art AT cut type | mold crystal vibrating piece.

In this embodiment, an AT-cut type crystal vibrating piece 10 will be described as an example of the crystal vibrating piece.
<Whole structure of the crystal unit 100>
Before describing the AT-cut type crystal vibrating piece 10, a crystal unit 100 in which the AT-cut type crystal vibrating piece 10 is accommodated will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view of a crystal unit 100 that accommodates an AT-cut type crystal resonator element 10.

  As shown in FIG. 1, the crystal unit 100 includes a package 18 formed of a piezoelectric material, ceramic, glass, or the like, and an AT-cut type crystal resonator element 10 accommodated therein. A pair of external electrodes 17 connected to an external power source (not shown) are formed at both ends of the bottom surface of the package 18. Here, the AT-cut type crystal vibrating piece 10 is composed of an AT-cut crystal piece 11. The AT cut is a cutting angle in which the main surface (YZ plane) is inclined 35 degrees 15 minutes from the Z axis in the Y axis direction with the X axis as the center with respect to the Y axis of the crystal axis (XYZ). Hereinafter, when the axial direction of the AT-cut type crystal vibrating piece 10 is expressed, the inclined new axes are usually referred to as the X ′ axis, the Y ′ axis, and the Z ′ axis, and these are used.

  Further, two pedestals 15 are provided on the lower surface of the internal space of the package 18, and the AT-cut type crystal vibrating piece 10 is fixed to the pedestal 15 via a conductive adhesive 16. Here, the vibration region 14 is formed in a reverse mesa shape on one main surface by etching. The quartz crystal piece 11 in which the vibration region 14 is formed has a pair of excitation electrodes 12 facing both main surfaces (front and back surfaces) near the center thereof. The thickness between the two main surfaces is about 2 μm to 10 μm. A pair of extraction electrodes 13 are connected to the pair of excitation electrodes 12, respectively. The AT-cut type crystal vibrating piece 10 mainly generates a vibration of several MHz to several hundred MHz by “thickness slip” in which the main surface moves in the opposite direction. For this reason, the thickness adjustment of the vibration region 14 and the thickness of the excitation electrode 12 or the extraction electrode 13 are very important.

  The pair of extraction electrodes 13 is configured to be thicker than the excitation electrode 12 and extends to both ends of the crystal piece 11 in the Z′-axis direction. The inside of the package 18 is in a vacuum or an inert gas state so that the excitation electrode 12 or the extraction electrode 13 is not easily oxidized. In the first embodiment, the AT-cut type crystal vibrating piece 10 in which the main surface on one side is an inverted mesa type will be described, but the AT-cut type crystal vibrating piece in which both main surfaces are an inverted mesa type Also good.

<Configuration of AT-Cut Quartz Vibrating Piece 10>
(First embodiment)
Hereinafter, a first embodiment of the AT-cut type crystal vibrating piece 10 will be described with reference to the drawings. FIG. 2 is a plan view of the AT-cut type crystal vibrating piece 10 according to the first embodiment. FIG. 3 is a plan view of the extraction electrode 13 of the AT-cut type crystal vibrating piece 10 of the first embodiment. Although the excitation electrode 12 and the extraction electrode 13 are formed simultaneously, only the portion of the extraction electrode 13 excluding the excitation electrode 12 is illustrated in FIG.

  As shown in FIG. 2, the AT-cut type crystal vibrating piece 10 is composed of a crystal piece 11 having an AT-cut width CW, and is symmetric with respect to the Z ′ axis passing through the center. Further, an inverted mesa type vibration region 14 is provided in the center of the crystal piece 11. An excitation electrode 12 is formed at the center of the vibration region 14, and the centers O of the pair of excitation electrodes 12 overlap each other in the Y′-axis direction. The fan-shaped center P of the pair of extraction electrodes 13 does not coincide with the center O of the excitation electrode 12. The fan-shaped centers P of the pair of extraction electrodes 13 extend beyond the center O of the excitation electrode 12 along the Z ′ axis. The radius R of the inverted mesa type vibration region 14 which is circular is about 0.25 mm. The radius r of the pair of excitation electrodes 12 is about 0.1 mm. The width CW of the crystal piece 11 is about 0.30 mm to 0.50 mm, and the width WW of the extraction electrode 13 is about 0.28 mm to 0.45 mm.

  As shown in FIG. 3, the extraction electrode 13 has a center angle θ (hereinafter referred to as an angle θ) in the middle of the excitation electrode 12 side in the X′-axis direction, and its radius is the same as the radius r of the excitation electrode 12. It has a certain hollow part 15. The center P of the hollow portion 15 does not coincide with the center O of the excitation electrode 12. In this specification, both ends of the arc of the extraction electrode 13 in contact with the hollow portion 15 are referred to as point A and point C. The arc points A and C of the extraction electrode 13 on one main surface coincide with the arc points A and C of the extraction electrode 13 on the other main surface. The points A and C of the extraction electrode 13 are on the circumference of the excitation electrode 12 and coincide with a position extending from the center O of the excitation electrode 12 in the X′-axis direction. At this time, the connection area CA between the excitation electrode 12 and the extraction electrode 13 corresponds to the outer periphery of the hollow portion 15.

  Further, the X′-axis direction of the extraction electrode 13 intersects the points B and D through the points A and C at both ends of the hollow portion 15 from the center P of the hollow portion 15. The central angle of the fan shape composed of the connecting line AB and the connecting line CD is also θ. The extraction electrode 13 has a fan-shaped angle θ composed of the connection line AB and the connection line CD of 90 ° or more and less than 180 °. For this reason, the angle θ in this embodiment is about 160 °.

  As shown in the first embodiment, when the angle θ of the connection region CA is about 160 °, the connection region CA between the extraction electrode 13 and the excitation electrode 12 is extended to the half circumference of the excitation electrode 12. For this reason, the crystal impedance CI becomes sufficiently small, and the electric energy is sufficiently supplied from the extraction electrode 13 to the excitation electrode 12 as indicated by the arrow AR in FIG. Further, since the area of the extraction electrode 13 is increased, the crystal impedance CI is further reduced. In addition, since the pair of extraction electrodes 13 provided on both main surfaces of the crystal piece 11 do not overlap each other, the equivalent parallel capacitance C0 does not increase. That is, when the angle θ of the connection area CA is about 160 °, the crystal impedance CI of the extraction electrode 13 is reduced and the equivalent parallel capacitance C0 is not increased. Therefore, the vibration characteristics of the AT-cut type crystal vibrating piece 10 are further improved. Can do.

FIG. 4 is a cross-sectional view of the AT-cut type crystal vibrating piece 10 from AA in FIG.
As shown in FIG. 4, the crystal blank 11 has a thin vibration region 14 at the center and a thick outer periphery that surrounds the outer periphery. Here, the thickness h of the central portion is preferably about 2 μm to 10 μm and the thickness H of the outer peripheral portion is preferably about 80 μm to 200 μm. Further, the extraction electrode 13 includes a first film 101 and a second film 102, and a third film 103 and a fourth film 104. The excitation electrode 12 formed in the middle of the central part is formed of the third film 103 and the fourth film 104. The first film 101 and the third film 103 are thinner than the second film 102 and the fourth film 104, and the second film 102 is thicker than the fourth film 104. In addition, the first film 101 and the third film 103 of the first embodiment may be made of a metal such as nickel (Ni) or chromium (Cr) according to product requirements, and the second film 102 and the fourth film 104. Is made of gold (Au).

  The first film 101 to the fourth film 104 of the extraction electrode 13 are formed by a vacuum deposition process and a photolithography process. The third film 103 and the fourth film 104 are formed simultaneously, that is, the excitation electrode 12 and the extraction electrode 13 are formed simultaneously. The extraction electrode 13 depicted in FIG. 3 coincides with the state in which the first film 101 and the second film 102 are formed and the third film 103 and the fourth film 104 are not formed.

  With the above-described configuration, the extraction electrode 13 is thicker than the excitation electrode 12 and is made of gold (Au) having excellent conductivity, so that the crystal impedance CI is further reduced. In addition, gold (Au) has high antioxidant and corrosion resistance and low chemical reactivity. Furthermore, when the crystal unit 100 is manufactured, higher electrical characteristics can be maintained even when exposed to a high temperature of 150 ° C. to 350 ° C. The reason why the excitation electrode 12 does not include the first film 101 and the second film 102 is that the thickness h of the central portion of the vibration region 14 is thin, so that if the excitation electrode 12 is thick, a high resonance frequency cannot be obtained. Because.

Furthermore, in order to make the frequency more stable, it is necessary to heat-treat the AT-cut type crystal vibrating piece 10 in the manufacturing process of the crystal device. At this time, stress is applied to the vibration region 14 due to the expansion of the extraction electrode 13, and the frequency variation of the AT-cut type crystal vibrating piece 10 occurs. This is particularly noticeable when the vibration region 14 is thin. Accordingly, in the first embodiment, the area of the extraction electrode 13 in the vibration region 14 increases as the fan-shaped central angle θ formed by the connection line AB and the connection line CD increases, and the AT-cut type crystal vibrating piece 10 is subjected to heat treatment. The frequency at the time of the change is changed.
The second embodiment is an embodiment for solving such a problem.

(Second embodiment)
Next, an AT-cut type crystal vibrating piece 10 according to a second embodiment will be described with reference to the drawings. FIG. 5 is a plan view of an AT-cut type crystal vibrating piece 10 according to the second embodiment. FIG. 6 is a plan view of the extraction electrode 13 of the AT-cut type crystal vibrating piece 10 of the second embodiment. The same components as those described in the first embodiment are denoted by the same reference numerals and described.

  As shown in FIG. 5, the AT-cut type crystal vibrating piece 10 of the second embodiment is improved on the basis of the first embodiment. In the second embodiment, the fan-shaped center P of the pair of extraction electrodes 13 coincides with the center O of the excitation electrode 12. Further, in the AT-cut type crystal vibrating piece 10 of the second embodiment, electric energy can be supplied from the half circumference of the excitation electrode 12 formed on both sides of the crystal piece as indicated by the arrow AR. For this reason, the supply of electrical energy is even better than in the first embodiment. Further, since the pair of extraction electrodes 13 provided on both surfaces of the crystal piece 11 do not overlap, the equivalent parallel capacitance C0 does not increase. Therefore, the AT-cut type crystal vibrating piece 10 having higher vibration characteristics can be obtained. Hereinafter, the shape of the extraction electrode 13 of the second embodiment will be described in detail with reference to FIG.

  As shown in FIG. 6, the extraction electrode 13 of the AT-cut type crystal vibrating piece 10 of the second embodiment includes a concentric semicircular portion 131 on the excitation electrode 12 side and a base portion on the end side in the Z′-axis direction. 132. First, the radius of the inner circle in the concentric semicircle portion 131 is the same as the radius r of the excitation electrode 12. The radius R1 of the outer circle is smaller than the radius R of the vibration region 14, and points E and F on the radius R1 of the outer circle from the center P of the hollow portion 15 through points A and C at both ends of the hollow portion 15. Intersect.

  The base portion 132 on the end side has the same shape as the extraction electrode 13 described in the first embodiment, and has a width WW. Next, the center P of the hollow portion 15 and the base portion 132 intersect with the points B and D of the base portion 132 via the points G and J on the circumference of the concentric semicircular portion 131. The concentric semicircular part 131 and the base part 132 are connected at points G and J. The central angle θ of the sector shape formed by the connection line GB and the connection line JD is 90 ° or more and less than 180 °.

  The cross section from AA of the AT-cut type crystal vibrating piece 10 of the second embodiment is also shown in FIG. 4, and the extraction electrode 13 of the AT-cut type crystal vibrating piece 10 includes the first film 101 and The second film 102, the third film 103, and the fourth film 104 are configured. In addition, the excitation electrode 12 formed in the middle of the central part is formed of the third film 103 and the fourth film 104.

  In addition, since the connection area CA between the excitation electrode 12 and the extraction electrode 13 is a half circumference of the excitation electrode 12, it is possible to reduce the crystal impedance CI and suppress an increase in the equivalent parallel capacitance CO. Therefore, the vibration characteristics of the AT-cut type crystal vibrating piece 10 can be enhanced. In the second embodiment, the area of the extraction electrode 13 in the vibration region 14 can be reduced even if the connection area CA between the excitation electrode 12 and the extraction electrode 13 is set to a half circumference of the excitation electrode 12. For this reason, the influence of stress can be suppressed and the frequency fluctuation of the AT-cut type quartz vibrating piece 10 can be suppressed.

  The optimum embodiment of the present invention has been described in detail above. However, as will be apparent to those skilled in the art, the present invention can be implemented with various modifications and variations within the technical scope thereof.

  For example, in the present invention, an AT-cut type crystal vibrating piece has been described as an example. The shape of the excitation electrode is not limited to the circular shape shown in the embodiment of the present invention, and may be variously changed and may be a polygon such as a quadrangle or a hexagon. Further, the material constituting the excitation electrode and the extraction electrode is not limited to the metal shown in the embodiment of the present invention, but may be a metal such as aluminum (Al), and the content of gold (Au) is 1 to 40 wt. % Gold (Au) silver (Ag) alloy. Further, as for the crystal piece, a thicker outer peripheral portion may be formed on one main surface as in the embodiment of the present invention, or may be formed on both main surfaces.

DESCRIPTION OF SYMBOLS 10, 70 ... AT cut type crystal vibrating piece 11, 71 ... Crystal piece 12, 72 ... Excitation electrode 13, 73 ... Extraction electrode 14 ... Vibration region 15 ... Base 16 ... Conductive adhesive 17 ... External electrode 18 ... Package 100 ... Quartz Crystal 101 ... First Film 102 ... Second Film 103 ... Third Film 104 ... Fourth Film 131 ... Concentric Semicircular Part 132 ... Base Part AR ... Electric Energy Supply CA ... Connection Area h ... Vibration Area Thickness O: center of excitation electrode 12 P: fan-shaped center of extraction electrode 13 H: thickness of outer periphery r: radius of excitation electrode R: radius of vibration region

Claims (8)

A quartz crystal vibrating piece comprising a quartz piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the quartz piece, and a pair of extraction electrodes that respectively extend from the excitation electrode,
The extraction electrode has a region extending from the vicinity of the center of the excitation electrode in a fan shape having a central angle θ of 90 ° or more and less than 180 °,
The center of the excitation electrode and the fan-shaped center of the extraction electrode do not coincide with the first direction, and the pair of the pair of the excitation electrode and the excitation electrode are in both the second direction orthogonal to the first direction and around the excitation electrode. A crystal vibrating piece characterized in that connecting lines extending in a fan shape of the extraction electrode intersect. A crystal piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the crystal piece, a semicircle portion connected to the excitation electrode, and a base portion arranged on the outer periphery of the semicircle portion A quartz crystal vibrating piece having a pair of extraction electrodes,
The semicircular portion of the extraction electrode has a center of the semicircular portion coinciding with the center of the excitation electrode and an inner periphery of the semicircular portion is connected to a half of the excitation electrode;
The quartz crystal resonator element according to claim 1, wherein the base portion has a fan-shaped region in which a center of the base portion coincides with the excitation electrode and a center angle θ is 90 ° or more and less than 180 °. The extraction electrode is formed by sequentially stacking a first film, a second film, a third film, and a fourth film on both sides of the crystal piece,
The excitation electrode is formed by sequentially stacking the third film and the fourth film on both sides of the crystal piece,
The quartz crystal vibrating piece according to claim 1, wherein the second film and the fourth film contain gold (Au). A quartz crystal vibrating piece comprising a quartz piece that vibrates in thickness, a pair of excitation electrodes formed on both sides of the quartz piece, and a pair of extraction electrodes that respectively extend from the excitation electrode,
The extraction electrode has a region extending in a fan shape having a central angle θ of 90 ° or more and 180 ° or less from the vicinity of the center of the excitation electrode, and the first film, the second film, the third film, and the fourth film are Sequentially stacked on both sides of the crystal piece,
The excitation electrode is formed by sequentially stacking the third film and the fourth film on both sides of the crystal piece,
The quartz crystal resonator element, wherein the second film and the fourth film contain gold (Au).   5. The quartz crystal vibrating piece according to claim 3, wherein the first film and the third film are thinner than the second film and the fourth film.   5. The quartz crystal vibrating piece according to claim 3, wherein the second film is thicker than the fourth film.   The quartz vibrating piece according to any one of claims 1 to 6, wherein the pair of excitation electrodes are polygonal or circular. A quartz crystal resonator element according to claim 1;
A package for fixing the crystal vibrating piece;
Crystal resonator with