Crystal Oscillator and Method for Manufacturing the Same

Abstract

This crystal oscillation element (102) comprises: a crystal piece (110) having a pair of main surfaces (112, 114) facing each other; and a pair of excitation electrodes (120, 130) provided to the pair of main surfaces (112, 114) of the crystal piece (110), wherein, with respect to an X-axis, Y-axis, and Z-axis as crystal axes of the crystal, when axes obtained by rotating the X-axis and the Y-axis by a rotation angle φ with the Z-axis as the axis of rotation are respectively defined as an X'-axis and a Y'-axis, and axes obtained by rotating the Y'-axis and the Z-axis by a rotation angle θ with the X'-axis as the axis of rotation are respectively defined as a Y''-axis and a Z'-axis, each of the pair of main surfaces (112, 114) of the crystal piece (110) is perpendicular to the Y''-axis, and when the angle formed between the X-axis and the X'-axis when the pair of main surfaces (112, 114) of the crystal piece (110) are viewed in a plan view is defined as ψ, the relationships ψ=α×φ×θ and α=±0.0165±0.016 are established.

Description

Technical Field

[0001] The present invention relates to a crystal oscillator and a method for manufacturing the same.

Background Art

[0002] In various electronic devices such as mobile communication terminals, communication base stations, and home appliances, crystal oscillators are used for applications such as timing devices, sensors, or oscillators. The crystal oscillator includes a crystal piece having a pair of main surfaces, and a pair of exciting electrodes provided on the pair of main surfaces of the crystal piece.

[0003] For example, Patent Document 1 discloses a crystal oscillator including a crystal piece having a rectangular planar shape obtained by rotating a plane perpendicular to the Y-axis of a crystal by φ degrees about the Z-axis of the crystal and further rotating the crystal by θ degrees about the X-axis of the crystal from that state, with the side along the X' axis being the first side and the side along the Z' axis being the second side.

[0004] Patent Document 2 discloses a crystal oscillator including a crystal piece having a pair of main surfaces parallel to an X' axis obtained by rotating the X-axis, which is a crystal axis of a crystal, by 15 to 25 degrees about the Z-axis, which is also a crystal axis of the crystal, and a Z' axis obtained by rotating the Z-axis by 33 to 34 degrees about the X' axis.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the crystal oscillator described in Patent Document 1, when the crystal is rotated by θ degrees, it is necessary to tilt the crystal to measure the angle, which may complicate the mechanisms of the angle measuring device and the crystal cutting device. For this reason, the angular accuracy of the crystal piece may decrease, and an increase in the ESR value due to an increase in the spurious oscillation and an increase in the temperature change of the frequency in a predetermined temperature range may occur.

[0007] Further, in the crystal oscillator described in Patent Document 2, since the angle formed by the X-axis and the X'-axis is large when the main surface of the crystal piece is viewed in plan, there has been a problem that the spurious oscillation increases and combines with the main oscillation to deteriorate the ESR value.

[0008] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a crystal oscillator having a small temperature change of frequency and a low ESR value and a simple manufacturing method thereof.

Means for Solving the Problems

[0009] The crystal oscillator according to one aspect of the present invention includes a crystal piece having a pair of main surfaces facing each other, and a pair of exciting electrodes provided on the pair of main surfaces of the crystal piece. With respect to the X-axis, Y-axis, and Z-axis, which are the crystal axes of the crystal, when the axes obtained by rotating the X-axis and the Y-axis by a rotation angle φ with the Z-axis as the rotation axis are defined as the X'-axis and the Y'-axis, respectively, and the axes obtained by rotating the Y'-axis and the Z-axis by a rotation angle θ with the X'-axis as the rotation axis are defined as the Y''-axis and the Z'-axis, respectively, each of the pair of main surfaces of the crystal piece is perpendicular to the Y''-axis. When the angle formed by the X-axis and the X'-axis when the pair of main surfaces of the crystal piece are viewed in plan is ψ, the relationship ψ = α × φ × θ and α = ±0.0165 ± 0.016 holds.

[0010] A method for manufacturing a crystal oscillator according to another aspect of the present invention is a method for manufacturing a crystal oscillator including a crystal piece having a pair of main surfaces facing each other and a pair of excitation electrodes provided on the pair of main surfaces of the crystal piece, the method including: preparing a crystal having crystal axes of an X-axis, a Y-axis, and a Z-axis; specifying an X'-axis and a Y'-axis obtained by rotating the X-axis and the Y-axis by a rotation angle φ with the Z-axis as a rotation axis; cutting the crystal along a plane perpendicular to the X'-axis; specifying a Y''-axis and a Z'-axis obtained by rotating the Y'-axis and the Z-axis by a rotation angle θ with the X'-axis as a rotation axis; and cutting the crystal along a plane perpendicular to the Y''-axis. Each of the pair of main surfaces of the crystal piece is perpendicular to the Y''-axis. When an angle formed by the X-axis and the X'-axis when the pair of main surfaces of the crystal piece is viewed in a plan view is ψ, a relationship of ψ = α × φ × θ and α = ±0.0165 ± 0.016 holds.

Effect of the Invention

[0011] According to the present invention, it is possible to provide a crystal oscillator with a small temperature change in frequency and a low ESR value, and a simple manufacturing method therefor.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0013] Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar components are denoted by the same or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be construed as being limited to the embodiments.

[0014] <Crystal Oscillator> First, with reference to FIGS. 1 to 2, the configuration of a crystal oscillator 100 according to an embodiment of the present invention will be described. FIG. 1 is an exploded perspective view of a crystal oscillator according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the crystal oscillator shown in FIG. 1.

[0015] The crystal oscillator 100 includes a crystal vibration element 102, a lid member 140, a base member 150, and a joining member 190. The crystal vibration element 102 is provided between the base member 150 and the lid member 140. The base member 150 and the lid member 140 constitute a holder for housing the crystal vibration element 102. In the example shown in FIGS. 1 and 2, the base member 150 has a flat plate shape, and the crystal vibration element 102 is housed in the concave portion of the lid member 140. However, as long as at least the excited portion of the crystal vibration element 102 is housed in the holder, the shapes of the base member 150 and the lid member 140 are not limited to the above. For example, the base member 150 may have a concave portion on the side of the lid member 140, or both the base member 150 and the lid member 140 may have concave portions on the sides facing each other.

[0016] The crystal oscillator 102 is an electromechanical energy conversion element capable of converting electrical energy and mechanical energy by the piezoelectric effect. The crystal oscillator 102 includes a crystal piece 110, a first excitation electrode 120 and a second excitation electrode 130 that form a pair of excitation electrodes, a first lead-out electrode 122 and a second lead-out electrode 132 that form a pair of lead-out electrodes, and a first connection electrode 124 and a second connection electrode 134 that form a pair of connection electrodes.

[0017] The crystal piece 110 has an upper surface 112 and a lower surface 114 that face each other. The upper surface 112 is located on the side opposite to the side facing the base member 30, that is, the side facing the top wall portion 141 of the lid member 140 described later. The lower surface 114 is located on the side facing the base member 150. The upper surface 112 and the lower surface 114 are rectangular. The upper surface 112 and the lower surface 114 correspond to a pair of main surfaces of the crystal piece 110.

[0018] The main vibration of the crystal oscillator 10 using the crystal piece 110 is the thickness shear vibration mode. In the examples shown in FIGS. 1 and 2, the upper surface 112 and the lower surface 114 of the crystal piece 110 are provided in a planar shape, but the present invention is not limited thereto. The upper surface 112 and the lower surface 114 may be provided in a mesa shape, an inverse mesa shape, a convex shape, or a bevel shape.

[0019] The first excitation electrode 120 and the second excitation electrode 130 apply a voltage to the crystal piece 110. The first excitation electrode 120 is provided on the upper surface 112 of the crystal piece 110, and the second excitation electrode 130 is provided on the lower surface 114 of the crystal piece 110. The first excitation electrode 120 and the second excitation electrode 130 face each other with the crystal piece 110 interposed therebetween. When the upper surface 112 of the crystal piece 110 is viewed in plan, the first excitation electrode 120 and the second excitation electrode 130 each have a rectangular shape and are arranged so that substantially the entire portions thereof overlap each other.

[0020] Note that the planar shape of each of the first excitation electrode 120 and the second excitation electrode 130 when the upper surface 112 of the crystal piece 110 is viewed in plan view is not limited to a rectangular shape. The planar shape of each of the first excitation electrode 120 and the second excitation electrode 130 may be a polygonal shape, a circular shape, an elliptical shape, or a combination thereof.

[0021] The first lead electrode 122 electrically connects the first excitation electrode 120 and the first connection electrode 124, and the second lead electrode 132 electrically connects the second excitation electrode 130 and the second connection electrode 134. The first lead electrode 122 is provided across the upper surface 112 to the lower surface 114 of the crystal piece 110, and the second lead electrode 132 is provided on the lower surface 114 of the crystal piece 110.

[0022] The first connection electrode 124 and the second connection electrode 134 electrically connect the crystal vibration element 102 to the base member 150. The first connection electrode 124 and the second connection electrode 134 are provided at both ends of one short side of the lower surface 114 of the crystal piece 110.

[0023] The first excitation electrode 120, the first lead electrode 122, and the first connection electrode 124 are integrally provided. The same applies to the second excitation electrode 130, the second lead electrode 132, and the second connection electrode 134. These electrodes of the crystal vibration element 102 have, for example, a multilayer structure provided by laminating a base layer and a surface layer in this order. For example, the base layer is a chromium (Cr) layer having good adhesion to the crystal piece 110, and the surface layer is a gold (Au) layer having good chemical stability.

[0024] The base member 150 holds the crystal vibration element 102 so as to be excitable. The base member 150 includes a base body 151, connection electrodes 160, 162, lead electrodes 164, 166, external electrodes 170, 172, 174, 176, and conductive holding members 180, 182.

[0025] The base body 151 is a plate-shaped insulator having an upper surface 152 and a lower surface 154 facing each other in the thickness direction. The upper surface 152 and the lower surface 154 correspond to a pair of main surfaces of the base body 151. The upper surface 152 is located on the side facing the crystal oscillator element 102 and the lid member 140, and corresponds to the mounting surface on which the crystal oscillator element 102 is mounted. From the viewpoint of suppressing the thermal stress acting on the crystal oscillator element 102 from the base body 151 due to a thermal history such as reflow, the base body 151 is preferably made of a heat-resistant material. From the same viewpoint, the base body 151 may be provided with a material having a thermal expansion coefficient close to that of the crystal piece 110. The base body 151 is provided, for example, by a ceramic substrate, a glass substrate, or a crystal substrate.

[0026] A corner portion of the base body 151 has a cutout side surface formed by cutting a part thereof into a cylindrical curved surface shape (also called a castellation shape). Note that the shape of the corner portion of the base body 151 is not limited to this, and the shape of the cutout may be planar, or there may be no cutout and a substantially right-angled corner portion may remain.

[0027] The connection electrodes 160 and 162 are electrically connected to the crystal oscillator element 102. The connection electrode 160 is electrically connected to the connection electrode 124 of the crystal oscillator element 102, and the connection electrode 162 is connected to the connection electrode 134 of the crystal oscillator element 102.

[0028] The lead-out electrode 164 electrically connects the connection electrode 160 and the external electrode 170, and the lead-out electrode 166 electrically connects the connection electrode 162 and the external electrode 172. The lead-out electrodes 164 and 166 are provided on the upper surface 152 of the base body 151.

[0029] The external electrodes 170 and 172 are external terminals for electrically connecting the crystal oscillator element 102 to an external substrate. The external electrode 170 electrically connects the first excitation electrode 120 of the crystal oscillator element 102 to the external substrate, and the external electrode 172 electrically connects the second excitation electrode 130 of the crystal oscillator element 102 to the external substrate. As an example, one of the external electrodes 174 and 176 is a ground electrode for grounding the lid member 140, and the other is a dummy electrode not electrically connected to the crystal oscillator element 102. Each of the external electrodes 170, 172, 174, and 176 is continuously provided from the cutout side surfaces provided at the four corner portions of the base body 151 to the lower surface 154. In the example shown in FIG. 1, the external electrode 170 and the external electrode 172 are located diagonally on the upper surface 152 of the base body 151, and the external electrode 174 and the external electrode 176 are located at another diagonal on the upper surface 152 of the base body 151. However, the external electrodes 170, 172, 174, and 176 are not limited to the above. Both of the external electrodes 174 and 176 may be ground electrodes, or both may be dummy electrodes. The external electrodes 174 and 176 may be omitted. The external electrode 174 may be electrically connected to one of the external electrodes 170 and 172, and the external electrode 176 may be electrically connected to the other of the external electrodes 170 and 172.

[0030] The conductive holding members 180 and 182 electrically connect the base member 150 and the crystal oscillator element 102 and mechanically hold the crystal oscillator element 102. The conductive holding member 180 electrically connects the first connection electrode 124 of the crystal oscillator element 102 and the connection electrode 160 of the base member 150. The conductive holding member 182 electrically connects the second connection electrode 134 of the crystal oscillator element 102 and the connection electrode 162 of the base member 150. The conductive holding members 180 and 182 are cured products of a conductive adhesive containing a thermosetting resin, a photocurable resin, or the like. The main component of the conductive holding members 180 and 182 is, for example, a silicone resin. The conductive holding members 180 and 182 contain conductive particles, and as the conductive particles, for example, metal particles containing silver (Ag) are used.

[0031] The main components of the conductivity maintaining members 180 and 182 are not limited to silicone resin, and may be, for example, epoxy resin, acrylic resin, or the like. Further, the conductive particles contained in the conductivity maintaining members 180 and 182 are not limited to silver particles, and may be formed of other metals, conductive ceramics, conductive organic materials, or the like. The conductivity maintaining members 180 and 182 may contain a conductive polymer.

[0032] The lid member 140 has a top wall portion 141 and a side wall portion 142 that extends from the outer edge portion of the top wall portion 141 toward the base member 150. The top wall portion 141 faces the base member 150 with the crystal vibration element 102 interposed therebetween, and the side wall portion 142 surrounds the crystal vibration element 102 with a space therebetween. The material of the lid member 140 is preferably a conductive material, and more preferably a metal material with high airtightness. By configuring the lid member 140 with a conductive material, an electromagnetic shielding function for reducing the entry and exit of electromagnetic waves into the internal space 101 is imparted to the lid member 140. From the viewpoint of suppressing the generation of thermal stress, the material of the lid member 140 is preferably a material having a thermal expansion coefficient close to that of the base member 150. For example, it is an Fe-Ni-Co alloy whose thermal expansion coefficient near room temperature coincides with that of glass or ceramic in a wide temperature range. The lid member 140 is electrically connected to at least one of the external electrodes 174 and 176 by a grounding member (not shown).

[0033] The joining member 190 joins the base member 150 and the lid member 140 and seals the internal space 101 in which the crystal oscillator 102 is housed. The joining member 190 is provided in a frame shape across the entire circumference of the outer edge portion of the base member 150 and is sandwiched between the tip portion of the side wall portion 142 of the lid member 140 and the upper surface 152 of the base member 150. The joining member 190 is provided with an insulating material. The joining member 190 is provided, for example, with an organic adhesive containing a resin such as an epoxy-based, vinyl-based, acrylic-based, urethane-based, or silicone-based resin. The material of the joining member 190 is not limited to the organic adhesive and may be provided with an inorganic adhesive such as a silicon-based adhesive containing water glass or the like or a calcium-based adhesive containing cement or the like. The material of the joining member 190 may be a low melting point glass (for example, a lead borate-based or tin phosphate-based glass).

[0034] Next, with reference to FIGS. 3 to 6, a more detailed configuration of the crystal piece 110 will be described. FIG. 3 is a diagram for explaining the angle of the crystal piece shown in FIG. 1. FIG. 4 is a graph for explaining the relationship between the rotation angle φ and the frequency temperature characteristic. FIG. 5 is a graph for explaining the relationship between the rotation angle θ and the frequency temperature characteristic. FIG. 6 is a graph for explaining the relationship between the rotation angle φ and the electromechanical coupling coefficient.

[0035] The main surfaces 112 and 114 of the crystal piece 110 are Z'X' planes perpendicular to the Y'' axis. The crystal piece 110 is formed by etching a crystal substrate (for example, a quartz wafer) obtained by cutting and polishing a crystal of synthetic quartz crystal.

[0036] As shown in FIG. 3, the upper surface 112 of the crystal piece 110 has a rectangular shape with a long side parallel to the X'-axis direction and a short side parallel to the Z'-axis direction. Further, the crystal piece 110 is plate-shaped with a thickness parallel to the Y''-axis direction. Here, the X'-axis, Y''-axis, and Z'-axis are defined based on the crystallographic axes of the crystal. Specifically, the X'-axis and Y'-axis are axes obtained by rotating the X-axis and Y-axis, which are the crystallographic axes of the crystal, by a rotation angle φ with the Z-axis, which is the crystallographic axis of the crystal, as the rotation axis. Also, the Y''-axis and Z'-axis are axes obtained by rotating the Y'-axis and Z-axis by a rotation angle θ with the X'-axis as the rotation axis. Note that the X-axis corresponds to the electrical axis (polar axis) of the crystal, the Y-axis corresponds to the mechanical axis of the crystal, and the Z-axis corresponds to the optical axis of the crystal.

[0037] When the upper surface 112 of the crystal piece 110 is viewed in plan view, when the angle formed by the X-axis and the X'-axis is ψ, the relationships ψ = α × φ × θ and α = ±0.0165 ± 0.016 hold. By using the crystal piece 110 with such an angle, it becomes possible to provide a crystal oscillator 102 having good frequency-temperature characteristics and suppressing the generation of sub-vibrations. Note that the angle ψ can be rephrased as the angle formed by the axis obtained by projecting the X-axis onto the upper surface along the Y''-axis and the X'-axis.

[0038] When the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z-axis, the relationship 1° ≤ φ ≤ 14° holds. As shown in FIG. 4, when the rotation angle φ is changed, the frequency-temperature curve shifts to the high-temperature side or the low-temperature side. When 1° ≤ φ ≤ 14°, compared with the case where φ = 0°, the frequency-temperature curve shifts to the high-temperature side. For this reason, the change in frequency in the high-temperature region is suppressed. Also, as shown in FIG. 6, when the rotation angle φ is changed, the electromechanical coupling coefficient k decreases with φ = 0° as the peak, and the sub-vibration increases. By establishing the relationship 1° ≤ φ ≤ 14°, the decrease in the electromechanical coupling coefficient k is suppressed, and the ESR value is kept low by suppressing the sub-vibration.

[0039] When the counterclockwise direction is defined as positive when viewed from the positive direction side of the X' axis, preferably, the relationship of 30 degrees ≤ θ ≤ 40 degrees holds. As shown in FIG. 5, when the rotation angle θ is changed, the frequency-temperature curve rotates around the inflection point. When 30 degrees ≤ θ ≤ 40 degrees, compared with the case of θ = 0 degrees, the frequency-temperature curve rotates clockwise. For this reason, the change in frequency in the low temperature range and the high temperature range is suppressed. By setting 1 degree ≤ φ ≤ 14 degrees and 30 degrees ≤ θ ≤ 40 degrees, the guaranteed temperature of the crystal oscillator 102 can be expanded to the high temperature side.

[0040] <Manufacturing method> Next, with reference to FIGS. 7 to 9, a manufacturing method of the crystal oscillator 102 according to an embodiment of the present invention will be described. FIG. 7 is a flowchart showing a part of the manufacturing method of the crystal oscillator according to an embodiment of the present invention. FIGS. 8 and 9 are diagrams for explaining the manufacturing method of the crystal oscillator according to an embodiment of the present invention.

[0041] First, a crystal XT0 is prepared (S110). The crystal XT0 is a crystal cut on the XY plane perpendicular to the Z axis.

[0042] Next, identify the X'-axis and Y'-axis of the crystal XT0 (S120), and cut the crystal XT0 along the ZX' plane and the Y'Z plane (S130). Place the crystal XT0 on the rotating stage such that one XY plane abuts against the placement surface of the rotating stage and the other XY plane faces upward. Next, while measuring the crystal orientation of the crystal XT0 with an X-ray orientation measuring device using the other XY plane as the measurement plane, rotate the rotating stage in the in-plane direction of the placement surface. Thereby, identify the X'-axis direction and Y'-axis direction of the crystal XT0. Next, cut the crystal XT0 on the rotating stage along the X'-axis and Y'-axis with the blade of a crystal cutting device provided perpendicular to the placement surface of the rotating stage. Thereby, as shown in FIG. 8, the crystal XT1 is cut out from the crystal XT0. In step S130, it is sufficient that the crystal XT0 is cut along the Y'Z plane, which will be the measurement plane of the X-ray orientation measuring device in the subsequent step S140, and it is not necessary to cut the crystal XT0 along the ZX' plane. For details of such crystal orientation measurement and cutting processing of the crystal, refer to the paper "MAKING DOUBLY ROTATED QUARTZ PLATES" published by W.L. Bond and J.A. Kusters at the 31th Annual Symposium on Frequency Control (June 1 - 3, 1977) (added to IEEE Xplore on December 5, 2005). The numerical values of the rotation angles in this embodiment were measured in accordance with this paper.

[0043] Next, identify the Y''-axis and Z'-axis of the crystal XT1 (S140), and cut the crystal XT1 along the X'Y'' plane and the Z'X' plane (S150). Similar to step S120, use the Y'Z plane of the crystal XT1 placed on the placement surface of the rotating stage as the measurement plane of the X-ray orientation measuring device to identify the Y''-axis direction and Z'-axis direction of the crystal XT1. Also, similar to step S130, cut the crystal XT1 on the rotating stage along the Y''-axis and Z'-axis. At this time, a plurality of substrate-shaped crystals XT2 are cut out from the crystal XT1.

[0044] Thereafter, for example, by etching, a plurality of crystal pieces 110 are formed in a single crystal XT2, and excitation electrodes and the like are provided to form a collective substrate for the crystal vibration element 102. At this time, by etching, a shape such as a mesa shape, an inverse mesa shape, a convex shape, or a bevel shape may be imparted to each of the plurality of crystal pieces 110. Finally, the collective substrate is separated into individual pieces to obtain the crystal vibration element 102. Note that the method of forming the plurality of crystal pieces 110 in the crystal XT2 is not limited to etching, and may be processing by mechanical cutting or the like. Further, the method of imparting a shape to each of the plurality of crystal pieces 110 is not limited to etching, and may be processing by chemical mechanical polishing or the like. The processing of imparting a shape to each of the plurality of crystal pieces 110 may be performed before providing the excitation electrodes and the like, or may be performed after providing the excitation electrodes and the like.

[0045] As described above, in the crystal vibration element 102 according to an embodiment of the present invention, with the Z-axis as the rotation axis, the axes obtained by rotating the X-axis and the Y-axis by the rotation angle φ are defined as the X'-axis and the Y'-axis, respectively. With the X'-axis as the rotation axis, the axes obtained by rotating the Y'-axis and the Z-axis by the rotation angle θ are defined as the Y''-axis and the Z'-axis, respectively. When the angle formed by the X-axis and the X'-axis when the pair of main surfaces 112 and 114 of the crystal piece 110 are viewed in plan view is ψ, the relationship ψ = α × φ × θ and α = ±0.0165 ± 0.016 holds.

[0046] According to this, a crystal vibration element 102 with a small temperature change in frequency and a low ESR value is provided.

[0047] As one aspect of the above, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z-axis, the relationship 1 degree ≤ φ ≤ 14 degrees holds.

[0048] According to this, the change in frequency in the high temperature range can be suppressed. Further, the decrease in the electromechanical coupling coefficient k is suppressed, and the ESR value can be kept low by suppressing the secondary vibration.

[0049] As one aspect of the above, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the X'-axis, the relationship 30 degrees ≤ θ ≤ 40 degrees holds.

[0050] According to this, it is possible to suppress the change in frequency in the low temperature range and the high temperature range.

[0051] As one aspect described above, each of the pair of main surfaces 112 and 114 of the crystal piece 110 is rectangular having sides parallel to the X' axis and the Z' axis.

[0052] According to this, it is possible to efficiently utilize the internal space 101 of the crystal oscillator 100 to maximize the size of the crystal piece 110. For this reason, the ESR value can be kept low.

[0053] Moreover, the manufacturing method of the crystal vibration element 102 according to another embodiment of the present invention includes specifying the Y'' axis and the Z' axis of the crystal XT1, cutting the crystal XT1 on the Z'Y' plane and the Z'X' plane, specifying the Y'' axis and the Z' axis of the crystal XT1, and cutting the crystal XT1 on the Z'Y' plane and the Z'X' plane.

[0054] According to this, it is possible to provide a crystal vibration element 102 having good frequency temperature characteristics and capable of suppressing the occurrence of sub-vibrations. Also, it is not necessary to tilt the crystal during measurement by the crystal orientation measuring device and during processing by the crystal cutting device. For this reason, compared with the manufacturing method of measuring the crystal orientation and cutting the crystal while tilting the crystal, the crystal vibration element 102 can be manufactured simply, and the angular error of the crystal piece 110 can be reduced.

[0055] Note that, in the crystal vibration element according to an embodiment of the present invention, the internal space 101 may be metal-sealed. That is, the base member and the lid member may be joined by a joining member made of a metal material. In this case, the connection electrode of the base member is separated from the sealing member, and the connection electrode of the base member and the external electrode are electrically connected by, for example, a through electrode penetrating the base member.

[0056] Hereinafter, some or all of the embodiments of the present invention are appended. Note that the present invention is not limited to the following appendices.

[0057] According to one aspect of the present invention, there is provided a quartz crystal unit including a quartz crystal piece having a pair of main surfaces facing each other and a pair of exciting electrodes provided on the pair of main surfaces of the quartz crystal piece. For the X-axis, Y-axis, and Z-axis which are the crystal axes of quartz, when the axes obtained by rotating the X-axis and Y-axis by a rotation angle φ around the Z-axis are defined as the X'-axis and Y'-axis respectively, and the axes obtained by rotating the Y'-axis and Z-axis by a rotation angle θ around the X'-axis are defined as the Y''-axis and Z'-axis respectively, each of the pair of main surfaces of the quartz crystal piece is perpendicular to the Y''-axis. When the angle formed by the X-axis and the X'-axis when the pair of main surfaces of the quartz crystal piece is viewed in plan view is ψ, a quartz crystal resonator is provided in which the relationship ψ = α × φ × θ and α = ±0.0165 ± 0.016 holds.

[0058] As one aspect of the above quartz crystal resonator, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z-axis, the relationship 1° ≤ φ ≤ 14° holds.

[0059] As one aspect of the above quartz crystal resonator, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the X'-axis, the relationship 30° ≤ θ ≤ 40° holds.

[0060] As one aspect of the above quartz crystal resonator, each of the pair of main surfaces of the quartz crystal piece is rectangular having sides parallel to the X'-axis and the Z'-axis.

[0061] As one aspect of the above quartz crystal resonator, the main vibration is a thickness-shear vibration mode.

[0062] There is provided a crystal oscillator including the quartz crystal resonator according to any one of the above aspects, a base member, and a lid member joined to the base member, wherein the quartz crystal resonator is provided in an internal space between the base member and the lid member.

[0063] According to another aspect of the present invention, there is provided a method for manufacturing a crystal oscillator comprising a crystal piece having a pair of main surfaces facing each other and a pair of exciting electrodes provided on the pair of main surfaces of the crystal piece, the method including: preparing a crystal having crystal axes X, Y, and Z; specifying X' and Y' axes obtained by rotating the X and Y axes by a rotation angle φ with the Z axis as a rotation axis; cutting the crystal along a plane perpendicular to the X' axis; specifying Y'' and Z' axes obtained by rotating the Y' and Z axes by a rotation angle θ with the X' axis as a rotation axis; and cutting the crystal along a plane perpendicular to the Y'' axis. Each of the pair of main surfaces of the crystal piece is perpendicular to the Y'' axis. When the angle formed by the X axis and the X' axis when the pair of main surfaces of the crystal piece are viewed in plan view is ψ, the relationship ψ = α × φ × θ and α = ±0.0165 ± 0.016 holds. A method for manufacturing a crystal oscillator is provided.

[0064] As one aspect of the method for manufacturing the crystal oscillator, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z axis, the relationship 1 degree ≤ φ ≤ 14 degrees holds.

[0065] As one aspect of the method for manufacturing the crystal oscillator, when the counterclockwise direction is defined as positive when viewed from the positive direction side of the X' axis, the relationship 30 degrees ≤ θ ≤ 40 degrees holds.

[0066] As one aspect of the method for manufacturing the crystal oscillator, the method further includes cutting the crystal along a plane perpendicular to the Z' axis, and each of the pair of main surfaces of the crystal piece has a rectangular shape having sides parallel to the X' axis and the Z' axis.

[0067] As described above, according to one aspect of the present invention, it is possible to provide a crystal oscillator with a small frequency temperature change and a low ESR value, and a simple manufacturing method therefor.

[0068] Note that the embodiments described above are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. The present invention can be modified / improved without departing from its gist, and the equivalents thereof are also included in the present invention. That is, as long as the features of the present invention are provided, those obtained by appropriately making design changes by those skilled in the art to the embodiments and / or modified examples are also included in the scope of the present invention. For example, each element included in the embodiments and / or modified examples and its arrangement, material, conditions, shape, size, etc. are not limited to those illustrated and can be appropriately changed. In addition, the embodiments and modified examples are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments and / or modified examples is possible, and these are also included in the scope of the present invention as long as they include the features of the present invention.

Explanation of Reference Numerals

[0069] 100... Crystal oscillator 101... Internal space 102... Crystal vibration element 110... Crystal piece 112... Upper surface 114... Lower surface 120... First excitation electrode 130... Second excitation electrode 122... First lead-out electrode 132... Second lead-out electrode 124... First connection electrode 134... Second connection electrode 150... Base member 140... Cover member 190... Joining member φ... Rotation angle with the Z-axis as the rotation axis θ... Rotation angle with the X'-axis as the rotation axis ψ... Angle formed by the X-axis and the X'-axis when the main surface of the crystal piece is viewed in plan

Claims

1. A crystal piece having a pair of main surfaces facing each other, and a pair of exciting electrodes provided on the pair of main surfaces of the crystal piece, With respect to the X-axis, Y-axis, and Z-axis, which are the crystal axes of the crystal, the axes obtained by rotating the X-axis and the Y-axis by a rotation angle φ with the Z-axis as the rotation axis are defined as the X'-axis and the Y'-axis, respectively, When the axes obtained by rotating the Y'-axis and the Z-axis by a rotation angle θ with the X'-axis as the rotation axis are defined as the Y''-axis and the Z'-axis, respectively, Each of the pair of main surfaces of the crystal piece is perpendicular to the Y''-axis, Each of the pair of main surfaces of the crystal piece has a rectangular shape having a short side and a long side, When the angle formed by the X-axis and the long side of the pair of main surfaces of the crystal piece when viewed in plan view is ψ, ψ = α × φ × θ, and α＝±０．０１６５±０．０１６ The relationship holds, A crystal oscillator.

2. When the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z-axis, 1 degree ≤ φ ≤ 14 degrees The relationship holds, The crystal oscillator according to Claim 1.

3. When the counterclockwise direction is defined as positive when viewed from the positive direction side of the X'-axis, 30 degrees ≤ θ ≤ 40 degrees The relationship holds, The crystal oscillator according to Claim 1 or 2.

4. Each of the pair of main surfaces of the crystal piece has sides parallel to the X'-axis and the Z'-axis, The crystal oscillator according to Claim 1.

5. The main vibration is a thickness shear vibration mode, The crystal oscillator according to Claim 1.

6. The crystal oscillator according to Claim 1, A base member, A lid member joined to the base member, Comprising, The crystal oscillator is provided in an internal space between the base member and the lid member.

7. A method for manufacturing a crystal oscillator comprising a crystal piece having a pair of main surfaces facing each other and a pair of exciting electrodes provided on the pair of main surfaces of the crystal piece, Preparing a crystal having crystal axes X-axis, Y-axis, and Z-axis, Identifying the X'-axis and the Y'-axis obtained by rotating the X-axis and the Y-axis by a rotation angle φ with the Z-axis as the rotation axis, Cutting the crystal with a plane perpendicular to the X'-axis, Identifying the Y''-axis and the Z'-axis obtained by rotating the Y'-axis and the Z-axis by a rotation angle θ with the X'-axis as the rotation axis, Cutting the crystal with a plane perpendicular to the Y''-axis Including, Each of the pair of main surfaces of the crystal piece is perpendicular to the Y''-axis, Each of the pair of main surfaces of the crystal piece has a rectangular shape having a short side and a long side, When the angle formed by the X-axis and the long side of the pair of main surfaces of the crystal wafer is ψ when the pair of main surfaces of the crystal wafer is viewed in plan view, ψ = α × φ × θ, and α＝±０．０１６５±０．０１６ the relationship holds, A method for manufacturing a crystal oscillator.

8. When the counterclockwise direction is defined as positive when viewed from the positive direction side of the Z-axis, 1 degree ≤ φ ≤ 14 degrees the relationship holds, The method for manufacturing a crystal oscillator according to claim 7.

9. When the counterclockwise direction is defined as positive when viewed from the positive direction side of the X'-axis, 30 degrees ≤ θ ≤ 40 degrees the relationship holds, The method for manufacturing a crystal oscillator according to claim 7 or 8.

10. further comprising cutting the crystal with a plane perpendicular to the Z'-axis, each of the pair of main surfaces of the crystal wafer has sides parallel to the X'-axis and the Z'-axis, The method for manufacturing a crystal oscillator according to claim 7.

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