JPH09139650A - Crystal oscillator and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce working costs, to provide good CI characteristics and to reduce dispersion in characteristics by forming a step by etching the section, where no electrode is formed, of a crystal element. SOLUTION: An exciting electrode 2 is circularly deposited so as to face the respective central parts of both the side plate faces of a crystal element for which the crystal of artificial crystal is cut at a prescribed angle to a crystal axis, segmented in the shape of plate and rectangularly formed. In this case, when depositing the exciting electrode 2, a lead electrode for deriving this exciting electrode 2 to the peripheral edge part of a crystal element 1 is formed as well. With the exciting electrode 2 itself as a mask, the crystal element 1 is immensed in etching liquid, a section 4 to form no exciting electrode 2 is etched and a step 3 is formed. Further, the section 4, where the exciting electrode 2 is not formed, of the crystal element 1 shown by slanting lines is etched and removed as shown by surrounding it by dotted lines. Thus, a lot of crystal elements can be simultaneously worked by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal unit capable of obtaining a good CI value and a manufacturing method thereof.

[0002]

2. Description of the Related Art Recently, piezoelectric vibrators have been used as a reference for frequency, time, etc. of various electronic devices. In particular, a crystal resonator using crystal as a piezoelectric body is widely used in many electronic devices because it has good electric characteristics and is inexpensive. In such a crystal unit, a crystal unit formed into a rectangular shape is used as a crystal unit having a small size, for example, a length of 5 to 5
Some have a width of about 8 mm and a width of about 2 mm.

However, if the shape of the crystal piece is reduced in this way, the crystal impedance (hereinafter referred to as CI), which is representative of the electrical characteristics of the crystal resonator, becomes high, and good vibration characteristics cannot be obtained. It was sometimes impossible to use it. For this reason, as a means for lowering the CI value, beveling for shaping the plate surface of the crystal blank into a curved surface is performed.

As an example of bevel processing, there is a method in which a large number of crystal pieces are housed together with an abrasive in a long cylindrical container and the containers are alternately inclined in the axial direction. By moving the crystal piece together with the polishing material from one end of the container to the other end, the plate surface of the crystal piece is polished into a curved surface that follows the inner wall of the container.

However, the bevel processing requires a long time for processing, and the processed strained layer remains on the surface of the crystal piece after processing, so that the surface roughness is large. Moreover, since it is difficult to make the processing amount and processing accuracy uniform, there are large variations in characteristics, and some crystal pieces cannot be used due to cracks, chips, etc. during processing.
For this reason, there has been a problem that the processing cost in the process of processing the crystal piece increases and the CI value cannot be lowered so much.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reduce the processing cost, obtain good CI characteristics, and particularly suitable for mass production. It is an object of the present invention to provide a crystal unit having less variation in characteristics of the crystal unit and a method for manufacturing the same.

[0007]

Means for Solving the Problems A first invention of the present invention is:
A second aspect of the present invention is a crystal resonator characterized in that a step is formed by etching a portion of the crystal piece where the electrode is not formed. A second aspect of the present invention is a step of forming an excitation electrode in a central portion of a plate surface of the crystal piece A method of manufacturing a crystal resonator, comprising: a step of etching a piece to form a step in a portion where an electrode is not formed; .

[0008]

1 is a plan view of a crystal resonator according to an embodiment of the present invention, and FIG. 2 is an exaggerated thickness shown in FIG.
This will be described in detail with reference to the sectional view taken along the line A and the flow chart shown in FIG. In the figure, reference numeral 1 denotes a crystal piece, which is obtained by cutting an artificial crystal crystal at a predetermined angle with respect to a crystal axis, cutting it into a plate shape, and molding it into a rectangular shape. The excitation electrodes 2 are vapor-deposited in a circular shape so as to face the central portions of both side plate surfaces of the crystal blank (see FIG. 3).
a). When depositing the excitation electrode 2, the excitation electrode 2
An extraction electrode for leading out to the peripheral portion of the crystal piece 1 is also formed.

Then, using the excitation electrode 2 itself as a mask,
The quartz piece 1 is dipped in an etching solution to etch a portion where the excitation electrode 2 is not formed to form a step 3 (FIG. 3b). At this time, a step is also formed in the portion where the extraction electrode is formed, but the ratio is generally smaller than the entire area of the crystal piece. As an etching liquid used for etching the crystal of quartz, for example, an ammonium fluoride solution may be used.

Then, a non-formation portion 4 of the excitation electrode 2 of the crystal blank 1 shown by hatching in FIG. 1 is removed by etching as shown by being surrounded by a broken line in FIG. By performing such etching, it is possible to remove the remaining portions such as fine cracks, chips, processing strains and the like that have occurred on the surface of the crystal piece in the processing steps such as cutting and polishing.

The crystal element 1 in which the excitation electrode 2 and the extraction electrode are formed in this way, and the portion where the electrode is not formed is etched, the crystal element 1 is held hermetically in a metal container or the like while holding the extraction end of the extraction electrode in the lead terminal. It is stopped and the excitation electrode is led out to the outside through the lead terminal and mounted on an electronic device or the like for use.

In this way, a large number of crystal pieces can be collectively processed by etching. Then, by uniformly convection the etching liquid, the processing amount can be accurately controlled according to the processing time, and the processing amount can be easily made uniform. Further, unlike the mechanical bevel processing which has been widely performed conventionally, the surface roughness of the crystal piece after the processing is small, and the crystal piece is not damaged such as cracked or chipped. Further, by etching, the remaining layers such as fine cracks, chips, and processing strains on the surface of the crystal piece are removed, so that good vibration characteristics can be obtained.

The present invention is not limited to the above embodiment, but can be applied to various types of crystal resonators. Further, the etching step is not limited to wet etching using an etching solution, and it goes without saying that dry etching using gas may be performed.

Further, in the above embodiment, the excitation electrode 2 is used as a mask, but a mask capable of protecting the excitation electrode 2 without being attacked during etching is formed on the excitation electrode 2. May be. In this case, it is necessary to remove the mask after etching is completed. Further, in the above-described embodiment, the extraction electrode is also formed when the excitation electrode 2 is formed, but the extraction electrode may be formed after the etching is completed.
This is effective in the case of a small crystal resonator in which the area of the extraction electrode occupies a large proportion of the area of the crystal piece.

[0015]

As described above in detail, according to the present invention, it is possible to process a large amount of crystal pieces at a low cost, is suitable for mass production, has a good CI characteristic and a small variation in the characteristic, and a crystal resonator thereof. A manufacturing method can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a crystal piece of a crystal resonator according to an embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of the plan view shown in FIG.

FIG. 3 is a flow chart illustrating the method of the present invention.

[Explanation of symbols]

 1 Quartz piece 2 Excitation electrode 3 Step 4 Non-formed part (of electrode) 5 Extraction electrode

Claims (4)

[Claims] 1. A crystal resonator, wherein a portion of a crystal piece where no electrode is formed is etched to form a step at the portion where no electrode is formed. 2. A method of manufacturing a crystal resonator, comprising: a step of forming an excitation electrode in a central portion of a plate surface of a crystal piece; and a step of etching the crystal piece to form a step at a portion where an electrode is not formed. . 3. A crystal oscillator according to claim 2, wherein when forming the excitation electrodes, extraction electrodes for leading each excitation electrode to the end of the crystal piece are formed. Method. 4. The method for manufacturing a crystal resonator according to claim 2, wherein after the etching is performed, a lead electrode for leading each excitation electrode to the end of the crystal piece is formed.