JP2014168145A - Quartz oscillation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stabilized low CI value.SOLUTION: A quartz oscillation element includes a tabular crystal piece, an elliptical protrusion provided on the principal surface of the crystal piece, an excitation electrode provided on both principal surfaces of the crystal piece, and covering the protrusion, and a routing pattern provided at one end of the crystal piece, and connected with the excitation electrode. The excitation electrode has a side, directing the short side of the crystal piece, formed in a curved shape and the side, directing the long side, formed linearly. The protrusion provided on one principal surface of the crystal piece has the same or shorter minor axis and a longer major axis as compared with the protrusion provided on the other principal surface.

Description

  The present invention relates to a crystal resonator element used in a crystal device.

2. Description of the Related Art Conventionally, a quartz crystal element in which an excitation electrode made of a metal film is provided on a quartz piece has been used in a quartz device.
This crystal piece can be formed, for example, by using an AT-cut crystal wafer by using a conventionally known photolithography technique and etching technique.
Such a crystal resonator element includes a crystal piece having a quadrangular shape and a convex portion formed on the main surface, an elliptical excitation electrode provided at the center of both main surfaces of the crystal piece, and a crystal piece connected to the excitation electrode. It is comprised from the routing pattern provided in one edge part of a piece.
Here, a quadrangular convex portion is provided on the main surface of the crystal piece, and the plane center of the convex portion is provided in accordance with the plane center of the crystal piece.
Moreover, the excitation electrode is provided in the plane of the convex part provided in the crystal piece, and is provided in the position which made the plane center correspond with the plane center of a convex part (for example, refer patent document 1).
In addition, a crystal resonator element in which the convex portion and the excitation electrode are elliptical has been proposed (see, for example, Patent Document 2).
Such a crystal resonator element has a shape in which the side surface of the convex portion has an inclination angle that varies depending on the axial direction of the crystal by wet etching. The portion with this inclination angle is called the residual.

JP 2009-135830 A JP 2012-74860 A

The ideal state of the crystal resonator element is to maximize the vibration energy by the excitation electrode and confine the vibration energy near the edge of the crystal piece.
However, since the residue formed by the wet etching that occurs during the formation of the protrusion is formed on the protrusion formed on the crystal piece, it is considered that a uniform thickness is not formed and unnecessary vibration is generated. As a result, when the excitation electrode is formed after the elliptical convex portion is formed on the crystal piece, the CI value (crystal impedance value) fluctuates easily due to a temperature change. This variation is called a CI dip, and when the frequency-temperature characteristic is graphed, a variation in the CI value appears greatly in a predetermined temperature range.

  Therefore, an object of the present invention is to provide a crystal resonator element that obtains a stable low CI value.

  In order to solve the above-mentioned problems, the present invention provides a crystal resonator element, which is provided on a plate-like crystal piece, an elliptical convex portion provided on the main surface of the crystal piece, and both main surfaces of the crystal piece. An excitation electrode that covers the convex portion, and a routing pattern that is provided at one end of the crystal piece and is connected to the excitation electrode. The excitation electrode has a curved side that faces the short side of the crystal piece. The side facing the long side is formed in a straight line, and the convex portion provided on one main surface of the crystal piece is the same short diameter as the convex portion provided on the other main surface of the crystal piece And having a long major axis.

  Further, the present invention is a crystal resonator element, comprising a plate-shaped crystal piece, an elliptical convex portion provided on a main surface of the crystal piece, and the convex portions provided on both main surfaces of the crystal piece. An excitation electrode to be covered and a routing pattern provided at one end of the crystal piece and connected to the excitation electrode, and the excitation electrode is formed in a curved shape with a side facing the short side of the crystal piece The side facing the long side is formed in a straight line, and the convex part provided on one main surface of the crystal piece has a short diameter and a long major axis shorter than the convex part provided on the other main surface of the crystal piece. It is characterized by comprising.

  In such a crystal resonator element, with respect to the shape of the protrusions provided on both main surfaces of the crystal piece, the protrusion provided on one main surface of the crystal piece is more than the protrusion provided on the other main surface of the crystal piece. Since it is configured with the same short diameter and a long long diameter, the variation in thickness due to the etching residue formed on the convex portion is reduced as compared with the prior art, thereby preventing the occurrence of unnecessary vibration and stable CI without CI dip. Value temperature characteristics can be obtained.

  In such a crystal resonator element, with respect to the shape of the protrusions provided on both main surfaces of the crystal piece, the protrusion provided on one main surface of the crystal piece is more than the protrusion provided on the other main surface of the crystal piece. Since it is configured with a short minor axis and a long major axis, the variation in thickness due to etching residue formed on the convex portion is reduced as compared with the prior art, thereby preventing the occurrence of unnecessary vibration and stable CI without CI dip. Value temperature characteristics can be obtained.

(A) is a schematic diagram which shows an example of the crystal oscillation element which concerns on embodiment of this invention, (b) is the side view which exaggerated and showed the short side of the crystal piece, (c) is a crystal piece It is the side view which exaggerated and showed the long side of this. It is a mimetic diagram showing the modification of the crystal oscillation element concerning the embodiment of the present invention. It is a graph which shows an example of CI value temperature characteristic of the crystal oscillation element concerning the embodiment of the present invention. The crystal oscillation element used for the comparison with the crystal oscillation element which concerns on embodiment of this invention is shown, (a) is a top view of a crystal oscillation element, (b) is a side view, (c) is other It is a top view of a crystal oscillation element. It is a graph which shows an example of the CI value temperature characteristic of the crystal oscillation element used for comparison with the crystal oscillation element which concerns on embodiment of this invention. It is a graph which shows an example of the CI value temperature characteristic of the other crystal oscillation element used for the comparison with the crystal oscillation element which concerns on embodiment of this invention.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. Note that each component is exaggerated for easy understanding of the state. Further, when referring to the main surface of the crystal piece, the main surface is defined as the widest surface of the planes appearing on the crystal piece and a surface parallel to the wide surface.

As shown in FIGS. 1A to 1C, a crystal resonator element 11 according to an embodiment of the present invention is provided on a crystal piece 1 having a quadrangular shape and provided with convex portions and both main surfaces of the crystal piece 1. And a routing pattern 3 connected to the excitation electrode 2 and routed to one end of the crystal piece 1.
In the crystal resonator element 11 according to this embodiment of the present invention, the intersection of the center line passing through the center of the long side of the crystal piece 1 and the center line passing through the center of the short side of the crystal piece 1 is the plane center C1 of the crystal piece 1. The plane center C2 of the convex portion and the plane center C1 of the crystal piece are formed to coincide with each other, and the plane center C3 of the excitation electrode 2 is formed to be shifted to the short side where the routing pattern 3 of the crystal piece 1 is not provided. Has been.

The crystal piece 1 is formed in a rectangular shape and a flat plate shape from, for example, an AT-cut crystal wafer.
The crystal piece 1 has a long side parallel to the X axis, a short side parallel to the Z ′ axis, and a thickness parallel to the Y ′ axis direction.
Further, as shown in FIGS. 1A to 1C, convex portions 1 a and 1 b are provided on both main surfaces of the crystal piece 1. The plane center C2 of the convex portions 1a and 1b is a position that coincides with the center C1 of the projection surface of the crystal piece 1 in plan view.

The convex portions 1 a and 1 b provided on both main surfaces of the crystal piece 1 are formed in an elliptical shape, the major axis of the ellipse is parallel to the long side of the crystal piece 11, and the minor axis of the ellipse is It is provided so as to be parallel to the short side.
Here, the convex part 1b provided in one main surface of the crystal piece 1 is provided so that it may have the same short diameter and a long long diameter as the convex part 1a provided in the other main surface of the crystal piece 1. That is, the convex part 1b will be in the state formed long with respect to the convex part 1a.

This crystal piece 1 can be formed using a conventionally known photolithography technique and etching technique. The crystal piece 1 has a crystal face of crystal on the side surface. The residue formed on the side surface of the crystal piece 1 is omitted.
The crystal piece 1 has an end portion where the routing pattern 3 is provided as the + X direction of the X axis and an opposite end portion as the −X direction.

At this time, as shown in FIG. 1 (b), in the Z-axis direction, the convex portion 1a has a residue with an inclination angle that enters the inside of the convex portion 1a, and this side surface along the Z-axis direction. On the opposite side, a residue with a tilt angle that protrudes outward is produced on the side surface.
On the other hand, the convex portion 1b has a side surface with a residue having an inclination angle that protrudes outside at a position opposite to the side surface where the residue with an inclination angle entering the inside of the convex portion 1a is generated. The residue with the inclination angle which enters the inside of the convex part 1b is generated on the side surface at a position opposite to the side surface where the residue with the inclination angle protruding outside the surface is generated.

In the crystal resonator element 11 according to the embodiment of the present invention having the convex portion 1a and the convex portion 1b, Z portions having different thicknesses are formed on portions having different thicknesses due to the residues generated on the convex portions 1a and 1b. When the length portion in the axial direction is ΔW1, the length portion ΔW1 in the Z-axis direction can be made smaller than the conventional one.
Therefore, since the thickness variation due to the etching residue formed on the convex portion is reduced as compared with the conventional case, unnecessary vibration can be prevented. Accordingly, the crystal resonator element 10 according to the embodiment of the present invention can obtain a stable CI value temperature characteristic without CI dip.

In addition, as a modification, the convex part 1a and the convex part 1b are provided with the convex part 1b provided on one main surface of the crystal piece 1 on the other main surface of the crystal piece 1 as shown in FIG. The crystal resonator element 12 may be configured to have a short diameter shorter than the convex portion 1a and a long long diameter. That is, the convex part 1b will be in the state formed thinly and long with respect to the convex part 1a.
Even if comprised in this way, since the dispersion | variation in the thickness by the etching residue formed in a convex part reduces conventionally, generation | occurrence | production of an unnecessary vibration can be prevented. Accordingly, the crystal resonator element 10 according to the embodiment of the present invention can obtain a stable CI value temperature characteristic without CI dip.

As shown in FIG. 1A, the excitation electrode 2 is provided on the crystal piece 1 so as to cover the convex portions 1a and 1b. In the excitation electrode 2, the side facing the short side of the crystal piece 1 is formed in a curved shape, and the side facing the long side of the crystal piece 1 is formed in a straight line.
The excitation electrode 2 provided so as to cover the convex portions 1a and 1b may be formed using an elliptical shape, or may be configured in a shape in which the minor axis side is formed in a straight line in the elliptical shape.

  The routing pattern 3 is provided at one end of the crystal piece 1 and is connected to the excitation electrode 2. The routing pattern 3 is provided along the edge of the main surface of the crystal piece 1.

For example, the routing pattern 3 includes two pairs of connection pads 3a and routing wirings 3b. The connection pads 3a are provided side by side at the corners of both main surfaces of the crystal piece 1, and one connection pad 3a is connected to the excitation electrode 2 provided on one main surface via the lead wiring 3b. Another connection pad 3a is connected to the excitation electrode 2 provided on the other main surface via the lead wiring 3b.
Further, the routing wiring 3b is formed in a straight line along the edge of the main surface of the crystal piece 1, and is provided from the excitation electrode 2 to the connection pad 3a.

  In the crystal resonator element 11 according to the embodiment of the present invention configured as described above, for example, as shown in FIG. 3, CI dip does not occur, and the CI value becomes a value that falls between about 40Ω to 50Ω and is stable. CI value temperature characteristics could be obtained.

On the other hand, for example, as shown in FIGS. 4A and 4B, elliptical convex portions are provided on both main surfaces of the crystal piece 1, and the other convex portion is provided on one main surface of the crystal piece 1. The crystal resonator element 21 in which the minor axis and the major axis of the convex portion of the main surface are formed large was examined.
As shown in FIG. 4B, the quartz resonator element 21 has different lengths in the Z-axis direction for portions having different thicknesses due to residues generated on the convex portions provided on both main surfaces of the quartz piece. When the portions are ΔW2 and ΔW3, the distance between the length portions ΔW2 and ΔW3 in the Z-axis direction is different and the symmetry is lost, and the total length of ΔW2 and ΔW3 is The quartz resonator element 11 according to the embodiment of the present invention is longer than the length portions ΔW1 + ΔW1 in the Z-axis direction having different thicknesses.
In the case of this crystal resonator element 21, as shown in FIG. 5, a CI dip in which the CI value suddenly increases around -10 ° C. occurred.

Also, for example, as shown in FIG. 4C, an elliptical convex portion is provided on both main surfaces of the crystal piece, and the convex portion of one main surface of the crystal piece and the convex portion of the other main surface are the same. The crystal resonator element 22 formed in a shape was examined.
In the case of this crystal resonator element 21, CI dip did not occur as shown in FIG. 6, but the CI value became a value between about 80Ω and 100Ω.
4, 5, and 6, “Temp (° C.)” means temperature, and on the vertical axis, “CI (Ω)” means CI value.

  Accordingly, the crystal resonator element 11 according to the embodiment of the present invention can obtain a stable CI value temperature characteristic without CI dip.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment.

DESCRIPTION OF SYMBOLS 11, 12 Crystal resonator element 1 Crystal piece 1a, 1b Convex part 2 Excitation electrode 3 Leading pattern C1, C2, C3 Plane center

Claims (2)

A flat crystal piece,
An elliptical convex portion provided on the main surface of the crystal piece;
An excitation electrode provided on both main surfaces of the crystal piece and covering the convex portion;
Provided at one end of this crystal piece, with a routing pattern connected to the excitation electrode,
The excitation electrode is formed such that the side facing the short side of the crystal piece is formed in a curved shape while the side facing the long side is formed in a straight line,
The quartz crystal resonator element, wherein a convex portion provided on one main surface of the crystal piece has a shorter diameter and a longer long diameter than a convex portion provided on the other main surface of the crystal piece. . A flat crystal piece,
An elliptical convex portion provided on the main surface of the crystal piece;
An excitation electrode provided on both main surfaces of the crystal piece and covering the convex portion;
Provided at one end of this crystal piece, with a routing pattern connected to the excitation electrode,
The excitation electrode is formed such that the side facing the short side of the crystal piece is formed in a curved shape while the side facing the long side is formed in a straight line,
A crystal resonator element, wherein a convex portion provided on one main surface of the crystal piece has a shorter and longer major diameter than a convex portion provided on the other main surface of the crystal piece. .

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