JPH07202629A - Crystal oscillator and manufacture of the same - Google Patents

Abstract

PURPOSE:To extremely effectively suppress sprious by making a plane to generate the sprious to adversely affect main oscillation coarser than a main oscillating plane. CONSTITUTION:Concerning a crystal board 1 for oscillation, the main oscillating plane wrapped by the #4000 finish of AT cut crystal blank at 12MHz, for example, is protected by regist for sand blast and since its external shape is worked into 2mmX3mm by sand blast, the planes excepting for the main oscillating plane are made coarser than the main operating plane. In this case, the osicllator is provided with regist 5 for sand blast, abrasive grain 6 for sand blast and glass board 7 for reinforce. On the other hand, an exciting electric wire 3 is formed by performing the 100Angstrom and 1000Angstrom vacuum deposition of chrome and gold on a pair of main oscillating planes of a crystal plate 10A for oscillation. The provided crystal plate for oscillation is fixed to a holding part 4 by conductive paste.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal unit, and more particularly to a crystal unit including a plate-shaped vibrating section.

[0002]

2. Description of the Related Art Crystal oscillators have high stability,
It is used as an important device indispensable for information communication. With the development of satellite communication and mobile phones in recent years,
One of the major goals is to reduce the size and increase the performance of each device, but crystal units are no exception.

Crystal oscillators are required to have strict frequency stability. A crystal unit usually used for such a purpose is a crystal plate with a cut angle called AT cut whose main vibration is a resonance frequency that is inversely proportional to the thickness and is cut out into a circular or rectangular shape. Exciting electrodes facing each other are formed on the main vibrating surfaces of the set to form a vibrator.
However, in the case of this cut angle, CT or DT
It is also possible to excite contour sway vibrations in the mid-frequency band of the cut system. Vibrations other than the thickness sway (main vibration) are parasitic to the main vibration and are called parasitic vibrations (spurious). Since this spurious is a major cause of deteriorating the characteristics of the main vibration, efforts have been made to suppress the excitation. Normally, when a rectangular crystal blank is used, its width and length are set to a certain size so that the spurious resonance frequency that occurs does not occur near the resonance frequency of thickness siding vibration. The effect on vibration is reduced, and the vibration of spurious is suppressed by holding the crystal plate. The structure of a conventional crystal unit is shown in FIG. In this figure, 11 is a crystal plate, 12
Is a peripheral part, 13 is an excitation electrode, and 14 is a holding part. In the case of this example, the quartz plate 10 is a rectangular AT-cut quartz blank, and thickness stagnation vibration is excited by a pair of opposing excitation electrodes 11 formed on the main vibrating surface.

[0004]

However, according to the conventional method, when a resonator having a certain resonance frequency is newly prepared, crystal blanks of various sizes are actually prepared and the resonance characteristics thereof are measured to obtain a crystal. The width and length of the blank are determined by repeating trial and error to determine the size so that the main vibration is less affected by spurious. Therefore, the size of the crystal blank in which the spurious is less likely to affect the main vibration for each resonance frequency is unique to the resonance frequency. As described above, the situation in which the size of the crystal blank is slightly different for each frequency has been a major obstacle to mass production of such a crystal unit. In some cases, from the relationship between the temperature characteristics of spurious and the main vibration,
Even if the size of the crystal blank was determined so that they would not affect each other near room temperature, spurious and main vibration would overlap at a certain temperature, and the desired characteristics might not be obtained.

The present invention solves the above problems,
It suppresses the generation of spurious by a simple method, eliminates the need to re-determine the size of the crystal blank for which the main vibration is less affected by spurious for each resonance frequency, and facilitates the improvement of the resonance characteristics of the crystal resonator. The purpose is to facilitate mass production.

[0006]

In order to achieve the above-mentioned object, the crystal resonator of the present invention is a crystal plate used for a vibrating part of a crystal resonator, of which the excitation electrode is not formed. It is characterized in that at least one surface is made rougher than the main vibration surface.

[0007]

With the above-described structure, the surface that generates spurious is different from the surface that determines the main vibration. Therefore, it is effective to generate spurious by a simple method of roughening the surface. Can be suppressed to For this reason, it is not necessary to re-determine the size of the crystal blank in which spurious is less likely to affect the main vibration for each resonance frequency, making it easy to improve the resonance characteristics of the crystal unit and also to mass-produce it. Become.

[0008]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A is an external view of the inside of the crystal unit according to the present embodiment. In this figure, 1 is a vibrating crystal plate, 2 is a peripheral portion, 3 is an excitation electrode, 4
Is a holding unit.

In the case of the present embodiment, the vibrating crystal plate 1 has 12
The main vibration surface of the AT-cut quartz crystal blank for MHz that has been wrapped with # 4000 finish is protected by a sandblasting resist, and the external shape is sandblasted to 2
By processing to mm × 3 mm, the roughness of the surfaces other than the main vibration surface was made rougher than that of the main vibration surface. The situation at this time is shown in FIG.
It shows in (b). In this figure, 5 is a resist for sandblasting, 6 is abrasive grains for sandblasting, and 7 is a reinforcing glass plate. The excitation electrode 3 is the vibrating crystal plate 1
100Å of chrome and 100 of gold on the main vibration surface
It was formed by vacuum vapor deposition. The vibrating crystal plate thus obtained was fixed to the holding portion 4 with a conductive paste, and was vacuum-sealed in a case (not shown) to obtain a crystal resonator.

The resonance characteristics of the crystal unit thus obtained are shown in FIG. 1 (c). In addition, for comparison, the resonance characteristics of a conventional crystal unit having the same shape as that of the present embodiment but the roughness of the surfaces other than the main vibration surface are not rough because the outer shape is processed by a dicing machine are shown in FIG. ). Comparing these resonance characteristics, it can be seen that in the resonance characteristics of the conventional crystal resonator, there are some spurs on the higher frequency side than the main vibration. On the other hand, in the resonance characteristics of the crystal unit according to the present example, resonance other than the main vibration is not seen, and spurious is suppressed because the roughness of the surfaces other than the main vibration surface is larger than that of the main vibration surface. There is.

(Second Embodiment) A second embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2A is an external view of the crystal unit according to this embodiment. In this figure, the same reference numerals as those in FIG. 1 are the same as those described above, and the description thereof will be omitted.

In the case of the present embodiment, the vibrating crystal plate 1 is a large number of AT cut crystal blanks for 12 MHz, # 4000.
The main vibrating surfaces that have been wrapped by finishing are bonded together with electron wax to form a columnar shape, and the side surface is ground with sandpaper (# 500) so that the main vibrating surface has a shape of 2 mm x 3 mm. The roughness of the surfaces other than the vibration surface was made rougher than that of the main vibration surface. The state at this time is shown in FIG. In this figure, 8 is an electron wax for adhesion and 9 is a sandpaper. The excitation electrode 3 was formed by vacuum-depositing 100 l of chromium and 1000 l of gold on the main vibrating surface of the vibrating crystal plate 1 by vacuum vapor deposition. The vibrating crystal plate thus obtained was fixed to the holding portion 4 with a conductive paste, and was vacuum-sealed in a case (not shown) to obtain a crystal resonator.

In the resonance characteristics of the crystal resonator thus obtained, resonance other than the main vibration is not observed, and spurious is suppressed because the roughness of the surfaces other than the main vibration surface is larger than that of the main vibration surface. ing.

(Embodiment 3) A third embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 3A is an external view of the crystal unit according to this embodiment. In this figure, the same reference numerals as those in FIG. 1 are the same as those described above, and the description thereof will be omitted.

In the case of the present embodiment, the vibrating crystal plate 1 has 12
The main vibration surface of the AT-cut quartz blank for MHz that has been lapped with # 1000 finish is protected by a metal mask, the outer shape is processed by sandblasting to 2 mm × 3 mm, and then the main vibration surface is polished The roughness of the surfaces other than the vibration surface was made rougher than that of the main vibration surface. The state at this time is shown in FIG. In this figure, 10 is a metal mask. The excitation electrode 3 is the vibrating crystal plate 1
100Å of chrome and 100 of gold on the main vibration surface
It was formed by vacuum vapor deposition. The vibrating crystal plate thus obtained was fixed to the holding portion 4 with a conductive paste, and was vacuum-sealed in a case (not shown) to obtain a crystal resonator.

With respect to the resonance characteristics of the crystal resonator thus obtained, resonance other than the main vibration is not observed, and spurious is suppressed because the roughness of the surfaces other than the main vibration surface is larger than that of the main vibration surface. ing.

[0017]

As is apparent from the above embodiments, the crystal resonator of the present invention is made by a very simple method in which the surface for generating spurious which adversely affects the main vibration is made rougher than the main vibration surface. , Can suppress spurious emission very effectively. Further, it is not necessary to redetermine the size of the crystal blank in which the spurious is less likely to affect the main vibration for each resonance frequency. Therefore, the resonance characteristics of the crystal unit can be easily improved, and the mass production thereof can be facilitated. Therefore, the effect of the present invention is very large.

[Brief description of drawings]

FIG. 1A is an external view of the inside of a crystal unit according to the first embodiment. FIG. 1B is a diagram showing a processing method of a vibrating crystal plate according to the first embodiment. FIG. Resonance characteristic diagram of the crystal unit obtained by the example (d) is a resonance characteristic diagram of the conventional crystal unit having the same shape as the first embodiment

FIG. 2A is an external view of a crystal unit according to a second embodiment, and FIG. 2B is a diagram showing a method for processing a vibrating crystal plate according to the second embodiment.

3A is an external view of a crystal unit according to a third embodiment, and FIG. 3B is a diagram showing a processing method of a vibrating crystal plate according to the third embodiment.

FIG. 4 is a diagram showing a structure of a conventional crystal unit.

[Explanation of symbols]

 1 Vibration Quartz Plate 2 Peripheral Part 3 Excitation Electrode 4 Holding Part 5 Resist 6 Abrasive Grain 7 Reinforcing Glass Plate 8 Electron Wax 9 Sandpaper 10 Metal Mask

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Eda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A crystal plate used for a vibrating portion of a crystal resonator, wherein at least one of the surfaces other than the surface for exciting the main vibration is made rougher than the main vibration surface. And a crystal unit. 2. A quartz plate used for a vibrating portion of a quartz resonator, at least one surface of which is a surface other than the surface for exciting the main vibration, the surface for exciting the main vibration being covered with a protective material. The method for manufacturing a crystal unit is characterized in that the roughness of the crystal is made rougher than that of the main vibration surface by means of abrasive grains. 3. A surface for exciting main vibration of at least two or more crystal plates used for a vibrating portion of a crystal resonator is adhered to each other, and at least one side surface of the crystal plate is separated from the main vibration surface by abrasive grains. A method for manufacturing a crystal unit, which is also characterized by roughening. 4. A crystal plate used for a vibrating portion of a crystal resonator is machined with abrasive grains to polish the outer surface for exciting the main vibration, so that a surface other than the surface for exciting the main vibration is removed. A method for manufacturing a crystal unit, wherein the surface roughness is made rougher than that of the main vibrating surface.