JPH046286B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an SL cut crystal resonator, and an SL cut crystal resonator that prevents vibration leakage, improves various characteristics, and achieves miniaturization.

[Description of Prior Art] Crystal resonators are the most widely used piezoelectric resonators. 0.8~ using this crystal oscillator
When obtaining a low frequency band of several MHz, it has traditionally been difficult to manufacture as it lies at the boundary between a contour vibration system and a thickness shear vibration system. In other words, the shape of the contour vibration system was too small, making it difficult to process, and the effect of support had a large impact on the crystal resonator's performance, making it impossible to create a satisfactory product. On the other hand, in the case of a thickness-shear vibration system, although the influence of support is small, the frequency is inversely proportional to the thickness, so in order to obtain this low frequency band, the thickness inevitably becomes thicker, and the shape also becomes too large. However, there were difficulties in downsizing. In addition, in order to achieve miniaturization and high precision, it is assumed that many crystal resonators are molded at the same time by processing using photolithography. The crystal oscillator is too thick, making it difficult to etch it. However, in the case of a contour vibration system, the frequency hardly contributes to the thickness, so the thickness of the crystal oscillator can be made thinner. The present invention deals with a contour vibration system, which is conveniently processed by lithography.

Conventionally, this contour vibration system has a square shape.
CT cuts and DT cuts are known, but in order to further reduce the size, there are so-called HT cuts and SL cuts, which have a rectangular shape in which the X-axis direction is longer than the Z-axis direction. The present invention deals with the SL cut crystal resonator among these. Conventionally, this SL cut crystal resonator used wires to provide support and electrical lead-out at the center of the main surface of the crystal resonator, but as the size became smaller, manufacturing and structural difficulties arose. Instead, it is fabricated using a photolithography method and is attempted to be formed using energy confinement. FIG. 3 is a plan view showing an example of an SL cut crystal resonator processed by the photolithography method, but in order to prevent vibration leakage to the support part, the damping part must be made long.

[Object and structure of the present invention] The object of the present invention is to improve the above-mentioned drawbacks, and to improve the characteristics by preventing vibration leakage of the SL cut crystal resonator, and to improve the characteristics. The object of the present invention is to provide an SL cut crystal resonator that is miniaturized, has good dimensional accuracy, and is cost-reduced by processing using photolithography.

In order to achieve such an object, the present invention provides an SL cut crystal resonator in which the cutting direction (yxl) is from -51°30' to -53°30' and the support part is drawn out from the vibrator part and is integrally molded. , an SL cut crystal in which the ratio L/W of the length L to the width W of the vibrator part is 4.3, and the inclination angle θ between the parallel part of the long arm of the vibrator and the damping part is within the range of 19° to 42°. It is a vibrator.

[Explanation of Examples] FIG. 1 is a plan view showing this embodiment.

Since the SL cut crystal resonator 10 is molded by photolithography, its thickness is several tens of microns. The cut angle is set to -51°30' to -53°30', which is normally used in SL cuts, and is composed of a vibrator section 11 and a frame section 15. The vibrator part 11 includes a rectangular SL-cut vibrating part 12 approximately in the center and a damping part 1 whose width becomes smaller in the longitudinal direction of the vibrator part 11.
3, and the damping portions 13 are provided on both sides of the vibrating portion 12 in the short side direction. A support portion 14 is drawn out from approximately the center of the side surface of this damping portion 13 and reaches a frame portion 15 . The frame portion 15 surrounds the entire vibrator portion 11 to increase its strength and prevent it from being directly affected by external influences. The length L of the vibrator part 11,
The same width W, the length 1 of the vibrating part 12, and the vibrating part 12
The angle of inclination between the longitudinal direction of the damping portion 13 and the damping portion 13 is represented by θ. Note that the diagonal lines represent electrodes, and the electrode provided on the vibrating section 12 is an excitation electrode for exciting the vibrating section 12, and a lead-out electrode for electrical conduction from this excitation electrode to the frame section is provided.

Figure 2 shows the SL cut crystal resonator 10 in Figure 1.
is used, and when the side ratio L/W is 4.30, the CI of the SL cut crystal resonator 10 for this inclination angle θ is
(Crystal Impedance) value. The figure is a graph of a quadratic function, and the CI value is 1KΩ or less when the inclination angle θ is between 19° and 42°. Although it is preferable that the CI value be smaller, a value of 1KΩ or less is preferable because the current consumption of the circuit is small.

The present invention is not limited to the shape of the embodiment, but it is sufficient that the actual size ratio of the vibrating portion is between 3.80 and 4.82. Also, as in the embodiment, the vibrating part extends up to the boundary with the damping part, but when the boundary surface is uncertain, the length l of the excitation electrode is used as the vibrating part.

[Effects of the Present Invention] The present invention has found the optimum value for the tilt angle of the SL cut crystal resonator, and has increased the tilt angle and shortened the damping section, which is advantageous for miniaturization. This is one of the characteristics of crystal resonators.
We were able to lower the CI value and fully bring out the characteristics of the crystal resonator.

Furthermore, in the present invention, the support section is extended from the central part of the side surface of the damping section in the vibrator section, so that there is little vibration leakage and the characteristics of the vibrating section can be brought out. It also has a four-point support structure with strong impact resistance.

Furthermore, since it is processed using the photolithography method, it is now possible to mold many pieces from the same crystal plate at the same time compared to conventional SL cut, and it has become possible to mass-produce uniform products.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a correlation diagram between an inclination angle and a CI value, and FIG. 3 is a plan view of a conventional SL cut crystal resonator. 10... SL cut crystal oscillator, 11... Vibrator section, 13... Damping section, 14... Support section, L...
Length of the vibrator section, W...width of the vibrating section, θ...angle of inclination.

Claims (1)

[Claims] 1 The cutting direction (yxl) is from -51°30' to -53°30', and the support part is pulled out from the vibrator part and is integrally molded.
In the SL cut crystal resonator, when the ratio L/W of the length L to the width W of the resonator part is 4.3, the inclination angle θ between the parallel part of the long arm of the resonator and the damping part is in the range of 19° to 42°. SL cut crystal oscillator characterized by the fact that it is inside.