JPH0624305B2 - Crystal oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a small crystal oscillator widely used for information devices such as watches, microcomputers, cordless telephones and communication devices, and is manufactured by etching. The present invention relates to a crystal oscillator, and more specifically, to improvement of impact resistance thereof.

SUMMARY OF THE INVENTION The present invention is characterized by improving impact resistance of a vibrator by forming a metal film on an unetched portion and its peripheral portion caused by crystal structure anisotropy during etching. To do.

[Conventional technology]

In recent years, the production of crystal oscillators from a quartz wafer by etching has attracted a great deal of attention due to its high production efficiency. When this etching is used, it is easy to etch due to the structural anisotropy of the quartz single crystal. There is an axis and a non-easy axis, and there is a characteristic that etching residue is generated in the details of the oscillator shape that is pulled up, that is, the plan view of FIG. 4 is an example of a tuning fork type crystal oscillator, 1 is a vibration Part, 2
Is a support portion, 3 is a tuning fork portion, and 6 is an etching residue caused by structural anisotropy. Further, the plan view of FIG. 5 is an example in which an essential part of the long-side vertical vibrator is enlarged and shown. In the figure, 1 is a vibrating part, 2 is a supporting part, and 3'is a frame part. , And 6 are the remaining portions of the etching. Further, 1, 2 and 3 in FIG. 4 and 1, 2 and 3 in FIG. 5 are vibrator main bodies formed by photolithography, and the remaining etching portion 6
It is a desirable part not to have.

[Problems to be Solved by the Invention]

If such etching residue is present, the impact force generated at the time of dropping etc. is concentrated in this etching residue part and cracks are induced from there, which makes it very easy to be destroyed and the impact resistance is significantly reduced. This is due to the stress concentration in the remaining portion of the etching.

That is, FIGS. 6 (a) and 6 (b) are plan views showing the state of destruction of the oscillator due to this stress concentration.
Is an example of a tuning fork type oscillator, and (b) in the same figure is an example of a long-side vertical oscillator. Indicates the destroyed part.

Ideally, it is preferable to improve the impact resistance by removing this etching residual portion, but due to the structural anisotropy of the crystal, it is impossible to completely remove it during etching. Therefore, the impact resistance cannot be said to be sufficient, and there is a big problem that the high production efficiency due to the etching process is not sufficiently reflected.

An object of the present invention is to improve impact resistance deterioration due to stress concentration in the above-mentioned etching residual portion.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a crystal unit formed by etching, which has impact resistance by forming and reinforcing a metal film on the remaining portion of the etching and its surroundings caused by the crystal structure anisotropy. Is to improve.

[Action]

7 (a) and 7 (b) are schematic plan views for explaining the reinforcing action of the present invention. In FIG. 7 (a),
11 is a member, and 12 is an etching residue. When an external force F indicated by an arrow is applied to both sides of the member 11, stress concentration occurs at points A and B in the figure, and from both points Destruction occurs as shown in the section.

FIG. 7 (b) shows the same member as that shown in FIG. 7 (a) with the metal coating 13 formed thereon. Descriptions other than 13 in FIG. 7 (b) are the same as those shown in FIG. 7 (a). Even if an external force F is applied to both sides of 11, no destruction occurs.

The main effect of the present invention is to utilize the above effects. More specifically, the mechanical strength in the vicinity of stress concentration points A and B in FIG. 7 (a) and the stress in FIG. 7 (b) will be described. Comparing the mechanical strengths of the portions A'and B'in the vicinity of the concentration points A and B, the metal films are dispersed in a wider range as much as the metal film is formed, and the latter is reinforced, therefore the same. The destruction does not occur for the same stress concentration generated by the application of the external force F. The present invention is one in which the above principle is applied to an actual vibrator.

〔Example〕

1 (a) for explaining the present invention with reference to the drawings,
2 (b) shows two embodiments in which the present invention is applied to a tuning fork type vibrator. In FIG. 1 (a), 1 is a vibrating portion, 2 is a supporting portion, 3 is a tuning fork crotch portion, and 4 Reference numeral 5 is an excitation electrode, 6 is an etching residue, and 7 is a metal film formed on the etching residue of 6 and its peripheral portion in order to improve impact resistance.

FIG. 1 (b) shows another embodiment of the tuning fork type vibrator,
Reference numerals 2 and 3 are a vibrating portion, a support portion, and a tuning fork portion, respectively, as in FIG. The etching residue 6 and the metal film to be formed on the peripheral portion are integrally formed at the same time as the patterns of the excitation electrodes 4 and 5 as shown by hatching, but in order to prevent an electrical short circuit, The electrodes are separated in the vicinity of the central portion, and the electrode shape in the supporting portion 2 is omitted in FIGS. 1 (a) and 1 (b).

Next, FIG. 2 is a plan view of an essential part of an example in which the present invention is applied to a long-sided longitudinal vibrator. In the drawing, reference numerals 1, 2, 3'represent a vibrating part, a supporting part, and a frame part, respectively. Further, the etching remaining portion is 6.

The metal film to be formed on the unetched portion and the peripheral portion is integrally formed with the excitation electrodes 4 and 5 in the same step as shown by hatching, and has a reinforcing function as well as an electrode conduction.

FIG. 3 is a graph showing the occurrence rate of defective products due to drop impact in the case where the reinforcement of the present invention is applied and the case where the reinforcement is not provided. It can be seen that it has improved to almost 0%. This figure shows an example of a tuning fork type oscillator, but the same effect can be obtained also in other oscillators such as a long-sided vertical oscillator if the etching residue due to the etching process induces cracks. .

〔The invention's effect〕

That is, the present invention, the problem of impact resistance deterioration caused by the etching residual portion caused by the etching process, by forming a metal film on the etching residual portion and its peripheral portion, to increase the mechanical strength against stress concentration, It can be solved. Therefore, the high production efficiency of the original etching process can be sufficiently reflected in the manufacture of the crystal unit, and a great effect can be obtained.

[Brief description of drawings]

1A and 1B are plan views in which the present invention is applied to a tuning fork type vibrator. FIG. 2 is a plan view in which the present invention is applied to a long-sided longitudinal oscillator. FIG. 3 is a graph showing the result of the test in which the present invention was carried out. FIG. 4 is a plan view of a conventional tuning fork type vibrator, FIG. 5 is a plan view of a main part of a conventional long-side vertical vibrator, and FIGS. 6 (a) and 6 (b) are conventional vibrators. And FIG. 7A and FIG. 7B are plan views showing the action of improving the problem. 1 ... Vibration part 2 ... Support part 3 ... Tuning fork part 3 '... Frame part 4, 5 ... Excitation electrode 6 ... Etching residue 7 ... Metal film

Claims (1)

[Claims] 1. In a crystal resonator formed by etching, at least a particularly large external stress concentration portion, an intersection of an etching residual portion and a resonator main body caused by crystal structure anisotropy, or A quartz oscillator characterized by the fact that a metal film is formed around the intersections of the remaining etching portions.