JPH03116882A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric oscillator which is excellent in workability and electrical properties and adapted for increase in frequency by a method wherein a reinforcing plate provided with a through-hole is pasted on one of the primary faces of a piezoelectric piece, the other primary face is polished, and the part of the piezoelectric piece correspondent to the through-hole of the reinforcing plate is made to oscillate as an oscillating region. CONSTITUTION:A quartz piece 1 is formed, for instance, disc-shaped, a reinforcing plate 7 is formed of the same material with the quartz piece 1, and a through-hole 9 is provided to the center of the reinforcing plate 7. The reinforcing plate 7 is pasted on the primary face of the quartz piece 1, and then both sides of a composite plate 8 are polished. The peripheral part of the composite plate 8 where the quartz piece 1 and the reinforcing plate 7 are joined together is made to serve an oscillation depressing region and the part of the quartz piece 1 opposed to the through-hole 9 is made to serve as an oscillating region. Exciting electrodes 10 are formed on the centers of both sides of the oscillating region, and extraction electrodes 11 are extended to both the peripheral ends of the composite plate 8 respectively, and an oscillation frequency is determined based on the thickness of the oscillating region.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a piezoelectric resonator, and particularly to a crystal resonator that achieves high frequency thickness shear vibration.

(Background of the invention) Crystal resonators are commonly known for their excellent resonance characteristics (,t ff
It is widely used as an oscillator and filter element in i-devices, etc.

In recent years, there has been a trend toward higher frequencies due to congestion of communication lines and high-quality communications.

(Conventional technology) FIG. 4 is a diagram of a crystal resonator explaining a conventional example.

The crystal oscillator is, for example, an AT-cut disc-shaped crystal piece 1
Consisting of An excitation electrode 2 and an extraction electrode 3 are formed on both sides of the crystal blank 1 . Normally, the outer peripheries of both extended ends of the lead-out electric wire ei3 are held and sealed by a structure (not shown). Then, it is excited by an oscillation circuit (not shown) and exhibits a thickness shear vibration in which the two surfaces are displaced in opposite directions. Such thickness shear vibration is inversely proportional to the thickness t, and the smaller the thickness, the higher the vibration frequency f6. In other words,
f = /l (however, k is a piezoelectric constant and is usually 1670 to H7
・It is indicated by w+m). For example, when the vibration frequency is IOMHz, a thickness of 0.167 mm is required.

Note that the vibration frequency is a fundamental wave vibration, and the same applies hereinafter. 5. Normally, both sides are polished to the same thickness.

(Problems with the prior art) However, in such a crystal resonator, 1, for example, 10
When trying to obtain a vibration frequency of 0MIIZ.

The thickness of crystal piece 1 is 0.0167mm (16.7μm)
becomes. Therefore, in this case, damage etc. may occur and processing by polishing becomes difficult. Furthermore, even if it could be processed, there would be problems in holding the crystal piece 1, and in practice,
60 MIIZ was the limit.

For this reason, it has been proposed to thin the central portion 4 of the crystal piece 1 by ion milling and to hold the outer peripheral portion 5 thereof, as shown in the cross-sectional view of FIG. 5, for example.

Note that the reference numeral 6 in the figure is a ttt pole. However, in such a device, the parallelism and flatness of the central portion are impaired, and spurious noise, etc., are generated. There was a problem of deterioration of various mechanical and mechanical properties.

(Objective of the Invention) An object of the present invention is to provide a piezoelectric vibrator that has good workability and electrical characteristics and is suitable for high frequencies.

(Solution Means of the Invention) The present invention includes attaching a reinforcing plate having a through hole to one main surface of a piezoelectric piece, polishing the other main surface of the piezoelectric piece, and matching the through hole of the piezoelectric piece. The solution is to excite the inside of the area as a vibration region. An embodiment of the present invention will be described below.

(Embodiment) FIGS. 1 to 3 are diagrams of a crystal resonator for explaining an embodiment of the present invention. Note that the same parts as those in the previous embodiment drawings are given the same numbers and the explanation thereof will be simplified.

The crystal resonator is the AT cut crystal piece 1 mentioned above and the reinforcing plate 7.
It consists of a composite board 8 to which is pasted. The flatness and parallelism of the crystal blank 1 and the reinforcing plate 7 are maintained by polishing or the like in advance. The crystal piece 1 is, for example, disc-shaped with a diameter of 5 mm and a diameter of 50 μm.
The thickness is set to (30M 112). Further, the reinforcing plate 7 is made of the same material as the crystal blank 1, has a thickness of 100 μm, and has a 2 mm through hole 9 in the center as shown in FIG.

After reinforcing one main surface of the crystal blank 1 [7]
b)", polishing the composite plate 8 from both sides, for example, and polishing the crystal piece 1.
"Figure 1 (C)" where the thickness of the cable is approximately 16 pm (100 MHz). Note that the outer peripheral portion of the crystal blank 1 that joins with the reinforcing plate 7 is defined as a vibration suppressing portion, and the central portion facing the through hole 9 is defined as a vibration region. Then, at the center of the vibration area,
mm excitation electrodes 10 are formed, and extraction currents 1M11 are extended to the outer periphery of both ends of the composite plate 8. However, from the excitation electrode on one main surface of the crystal blank 1, there is a part extending from the excitation electrode to the surface of the reinforcing plate via the inner wall of the through hole, and a metal base as shown in Fig. 3. The structure is such that the outer periphery of both ends of the composite plate 8 is electrically and mechanically connected to and held by a supporter 13 erected on the supporter 12 .

In such a device, the thickness of the crystal blank 10 is about 50 μm, but the thickness of the composite plate 8 is 150 μm, so the crystal blank 1 can be sufficiently polished to a thickness of 16 μm without being damaged. A vibration frequency of 100MH2K is obtained depending on the thickness of the vibration region. In addition, since the crystal piece 1 and the reinforcing plate 7 satisfy flatness and parallelism in advance and are made thin by polishing,
Maintain the same qt degree and )μ surface skin of crystal piece 1. Also,
Since the thickness of the composite plate 8 after polishing is about 90 μm, the composite plate 8 can be easily held and a high frequency can be achieved. Furthermore, in this embodiment, since the reinforcing plate 7 is made of the same material as the crystal blank 1, there is no frequency change due to a difference in thermal expansion coefficients, and the electrical characteristics are improved6. The diameter of the region is 2 mm, corresponding to the through hole, but the thickness is very small, 16 μm, so the plate surface area is sufficient relative to the thickness and does not impede the vibration characteristics.

(Other matters) In the above example, the thickness of the crystal piece is 16 μm (1
00MIIZ), @The diameter of the moving area was set to 2 mm, etc., but the present invention is not limited to this, and it goes without saying that each dimension can be selected as appropriate.

In addition, although the vibration area portion was set to be a portion facing the through hole 9,
Since it is desirable that the displacement of the outer circumference of the vibration region be 0, this does not necessarily mean that the entire region vibrates. For example, by increasing the vibration area relative to the thickness, the displacement at the outer periphery can be brought close to O. In addition, the excitation electrode is
Although it is set at the center of the dynamic region, for example, if it is formed eccentrically from the center, overtone vibration can be caused, and a further increase in frequency can be expected. Further, although the outer peripheries of both ends of the composite board 7 are held by the supports 13, the auxiliary #iJI board may be directly fixed to, for example, a circuit board (not shown), and the holding structure is not limited to this. Furthermore, although the reinforcing plate 7 is made of the same material as the crystal piece 1, basically any material may be used as long as it is an insulator. For example, when the Z plate is made of quartz, there is no piezoelectric resonance in the Z plate portion, resulting in less secondary resonance. In short, the present invention can polish the crystal piece 1 by attaching a reinforcing plate when the crystal piece 1 is thin and difficult to polish.
It is intended to be configured and configured in a specific manner, and such is within its technical scope.

(Effects of the Invention) The present invention attaches a reinforcing plate having four holes to one main surface of a piezoelectric piece, polishes the other main surface of the piezoelectric piece, and corresponds to the through-holes of the piezoelectric piece. Since the vibration area is used as a vibration region and excited, it is possible to provide a piezoelectric vibrator suitable for high frequencies with good workability and electrical characteristics.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention, and FIG.
1 shows a disassembled composite board; FIG. 2(b) is a top view of the composite board before polishing, and FIG. 3(c) is a cross-sectional view of the same after polishing. FIG. 2 is a diagram of a composite plate on which electrodes are formed, and FIG. 3 is a diagram of the composite plate held. FIG. 4 and FIG. 5 are diagrams of a crystal resonator to explain a conventional example. M1 diagram (a) (1)) (C) Figure 3 n

Claims (2)

[Claims] (1) A reinforcing plate having a through hole is attached to one main surface of the piezoelectric piece, the other main surface of the piezoelectric piece is polished, and a vibration region is formed in the part of the piezoelectric piece corresponding to the through hole. A piezoelectric vibrator characterized by being excited as (2) The piezoelectric vibrator according to claim 1, wherein the reinforcing plate is made of the same material as the piezoelectric piece.