JP2014030114A - Crystal vibration element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal vibration element capable of reducing distortions in vibration displacement distribution to achieve low CI value.SOLUTION: A crystal vibration element comprises: a flat plate crystal piece; an excitation electrode provided on both main surfaces of the flat plate crystal piece; and a routing pattern provided on one edge of the crystal piece and connected to the excitation electrode. Four corners of a square on the main surface of the crystal piece are rounded with a predetermined radius R1, and have a salient formed into a shape having a long side and a short side. The excitation electrode covers the whole of the salient, four corners of the square are rounded with a predetermined radius R2, are formed into a shape having a long side and a short side, and the radius R1 formed in the salient and the radius R2 formed in the excitation electrode are same size.

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 formed in a quadrangle and having a convex portion formed on a main surface thereof, a square 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 closer to the end portion side of the crystal piece than the plane center of the crystal piece.
Moreover, the excitation electrode was provided so that the convex part provided in the crystal piece might be covered, and it was provided in the position which made the plane center correspond with the plane center of a convex part.
In this excitation electrode, the size of the portion protruding from the convex portion was the same in the long side direction and the short side direction (see, for example, Patent Document 1).

Japanese Patent No. 4506135

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, in the conventional quartz resonator element, the corners of the convex portions formed in a quadrangular shape and the corners of the excitation electrodes formed in a quadrangular shape are pointed, so that the ring shape is circular from the inner surface side to the outer peripheral side of the crystal piece. The transmitted vibration displacement distribution is distorted and the CI value (crystal impedance value) increases.

  Therefore, an object of the present invention is to provide a crystal resonator element that reduces distortion of a vibration displacement distribution in order to realize a low CI value.

  In order to solve the above-described problems, the present invention provides a crystal resonator element, which is provided on a flat plate-shaped crystal piece, excitation electrodes provided on both main surfaces of the crystal piece, and one end of the crystal piece. And a lead pattern connected to the excitation electrode, and a convex portion having a long side and a short side while rounding four corners of the quadrangle with a predetermined radius R1 on the main surface of the crystal piece, and the excitation electrode. Is formed in a shape having a long side and a short side while rounding the four corners of the quadrangle with a predetermined radius R2 while covering the entire convex part, and is formed on the radius R1 formed on the convex part and the excitation electrode. The radius R2 is formed with the same radius.

  In such a crystal resonator element, the crystal has the property that vibration is most easily transmitted in the X-axis direction and vibration in the Z′-axis direction is less easily transmitted than the X-axis. And the excitation electrode formed in a shape in which the four corners of the quadrangle are rounded with a predetermined radius R2, the radius of rounding the four corners of the quadrangle is the same size. R1 and the radius R2 on the side of the excitation electrode have the same way of vibration transmission, which can reduce the deviation of the vibration displacement distribution and reduce the occurrence of distortion.

(A) is a schematic diagram which shows an example of the crystal oscillation element which concerns on embodiment of this invention, (b) is AA sectional drawing of (a).

  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.

(First embodiment)
As shown in FIGS. 1 (a) and 1 (b), a crystal resonator element 10 according to the first embodiment of the present invention includes a rectangular crystal piece 1 and excitation electrodes provided on both main surfaces of the crystal piece 1. 2 and a routing pattern 3 connected to the excitation electrode 2 and routed to one end of the crystal piece 1.

The crystal piece 1 is formed in a rectangular shape and a flat plate shape from, for example, an AT-cut crystal wafer (not shown), and an m-plane 1b is provided on the side surface on the long side.
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, a convex portion 1 a is provided on the main surface of the crystal piece 1. The planar center C2 of the convex portion 1a is positioned in a state where it coincides with the center C1 of the projection surface of the crystal piece 1 in plan view. In addition, this convex part 1a will be in the state covered with the excitation electrode 2 mentioned later.

The convex portion 1 a is formed in a shape in which four corners of a quadrangle are rounded with a predetermined radius R 1, the long side of the convex portion 1 a is parallel to the long side of the crystal piece 10, and the short side is the short side of the crystal piece 10. It is provided so as to be parallel to the side.
This crystal piece 1 can be formed using a conventionally known photolithography technique and etching technique. Thus, the provided crystal piece 1 is in a state in which the m-plane 1b is formed on the side surface on the long side. In other words, the m-plane 1b is a crystal plane generated on the side surface side when the crystal is etched.
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.

As shown in FIG. 1A, the excitation electrode 2 has a shape in which four corners of a quadrangle are rounded with a predetermined radius R2, and is flat so that the straight side does not cover the m-plane 1b of the crystal piece 1. The center C3 is provided in accordance with the center C1 of the projection surface of the crystal piece 1 in plan view. In other words, the center C1 of the plane including the main surface and the m-plane 1b when the quartz crystal piece 1 is viewed in plan view and the plane center C3 of the excitation electrode 2 are in agreement.
The excitation electrode 2 is provided so that the long side is parallel to the long side of the convex portion 1a and the short side is parallel to the short side of the convex portion 1a.

  As shown in FIG. 1, the center of the plane including the main surface and the m-plane 1b when the crystal piece 1 is viewed in plan view is a center line CL1 passing through the center of the long side of the crystal piece 1, and the crystal It is also a point where the center line CL2 passing through the center of the short side in the plan view of the piece 1 intersects.

Further, the excitation electrodes 2 are provided on both main surfaces of the crystal piece 1 so as to face each other.
Here, the radius R1 formed on the convex portion 1a is formed with the same radius as the radius R2 formed on the excitation electrode 2.

  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.

The ideal state of the crystal resonator element is to confine the vibration energy near the edge of the crystal piece 1 by maximizing the vibration energy with the excitation electrode.
As described above, according to the crystal resonator element 10 according to the embodiment of the present invention, the crystal has the property that the vibration is most easily transmitted in the X-axis direction, and the vibration is less transmitted in the Z′-axis direction than the X-axis. Since the formed radius R2 is formed with the same size as the radius R1 formed on the convex portion 1a, the vibration R1 on the convex portion side and the radius R2 on the excitation electrode side are transmitted in the same manner, Deviation of the vibration displacement distribution can be reduced to reduce the occurrence of distortion. Accordingly, it is possible to realize a crystal resonator element in which vibration energy is easily confined on the end side of the crystal piece 1 and has a low CI value.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, if the crystal piece is provided with an m-plane, it is not limited to the AT cut, and crystal pieces having various cut angles can be used.
The excitation electrode may be provided so as to cover the m-plane formed on the crystal piece.

DESCRIPTION OF SYMBOLS 10 Crystal oscillator 1 Crystal piece 1a Convex part 1b m surface 2 Excitation electrode 3 Leading pattern C1, C2, C3 center

Claims (1)

A flat crystal piece,
Excitation electrodes provided on both main surfaces of the crystal piece;
Provided at one end of this crystal piece, with a routing pattern connected to the excitation electrode,
Protrusions having a long side and a short side while rounding the four corners of the quadrangle on the main surface of the crystal piece with a predetermined radius R1, are provided.
The excitation electrode is formed in a shape having a long side and a short side while covering the entire convex portion and rounding the four corners of the quadrangle with a predetermined radius R2.
The quartz crystal resonator element, wherein the radius R1 formed on the convex portion and the radius R2 formed on the excitation electrode are formed with the same radius.

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