JP2007104042A - Crystal resonation element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve various problems in a conventional technique that it takes a dozens of hours to a few hundred hours to process a crystal blank plate into a projection shape, that it is difficult to deal with small lots because crystal blank plates must be put into a processing container per thousands of sheets, and that the surface polishing state of each of the crystal blank plates in a polishing container cannot be controlled and this causes variations on the surface shape in a putting-in lot. <P>SOLUTION: In a crystal resonation element and its manufacturing method, electrodes for excitation formed oppositely between main surfaces on the front and rear surfaces of a crystal blank plate and a leading-out electrode extending from the electrodes for excitation to the external edge portion of the crystal blank plate are formed, and at least one or more circular or arc-like grooves formed concentrically at the center of each of the electrodes for excitation are formed on the main surface of the crystal blank plate by an ultrasonic spindle means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a crystal resonator element mounted in a piezoelectric device such as a crystal resonator and a manufacturing method thereof.

  A quartz crystal element mounted in a piezoelectric device such as a crystal oscillator or a crystal oscillator usually uses a quartz or rectangular crystal element. Quartz crystals used in crystal resonators with a relatively low vibration frequency (10 MHz or less) and crystal resonators that require high frequency stability improve the energy confinement effect and provide secondary vibration such as contour vibration. In order to improve the characteristics such as crystal impedance (hereinafter referred to as CI) and Q value by reducing the vibration loss due to the above, the outer shape is a convex shape as shown in FIG. In FIG. 4, the convex crystal resonator element 40 in which the excitation electrode 42 and the extraction electrode 43 are formed on both the front and back main surfaces of the crystal base plate 41 having a circular outer shape is disclosed. A quartz plate having a shape and a convex processing is also generally used.

  As a processing method for making the outer shape of the quartz base plate into a convex shape, a processing method by polishing has been conventionally employed. For example, a flat disk-shaped quartz plate main surface is pressed against the inner wall of a hemispherical polishing vessel having a spherical inner wall, and the polishing vessel or the quartz plate is slid, and the curvature of the inner wall is copied to the quartz plate main surface. Thus, a processing method for obtaining a convex shape by polishing is used (see, for example, Patent Document 1).

  In addition, a plurality of quartz plates and abrasives are put into a cylindrical polishing container having a plurality of curvatures on the inner wall, and the polishing container body is rotated and revolved so that the curvature of the inner wall is reflected on the main surface of the quartz plate. Thus, a processing method for obtaining a convex shape is also used (for example, see Patent Document 2).

JP-A-2-205466 (page 1-3, FIG. 1) JP 2001-1249 A (page 2-3, FIG. 1-4)

    In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the prior art document information described above.

  In the apparatus as described in Patent Document 1, in the case of processing a quartz base plate into a convex shape, only one to at most ten quartz base plates can be processed by one polishing, and production is possible. The property is extremely low. In addition, the convex processing using such an apparatus requires a certain size for the crystal plate to be processed, and it is not possible to use such a processing method for a crystal base plate that is currently being used in a compact size. It is very difficult.

  In the apparatus described in Patent Document 2, the processing efficiency for processing the surface of the quartz base plate into a convex shape generally depends on the load applied to the processing point. That is, in the crystal element plate whose outer shape is further reduced in size, the mass of the crystal element plate is greatly reduced, which causes a significant reduction in processing efficiency.

  As a polishing container constituting such an apparatus, a metal polishing container having a diameter of about 50 to 200 mm and a length of about 300 to 600 mm is generally used, and the strength of the polishing container is ensured. Therefore, increasing the wall thickness of the polishing container increases the weight. Therefore, the strength of the apparatus itself incorporating this polishing container needs to be very high, and its weight is generally about 1 t or more and becomes large, so the installation space for the apparatus must be wide and able to withstand the weight. There is.

  Because the weight of the polishing container is heavy, even if a large motor is used, the revolution speed of the polishing container can only be obtained up to about a few hundred tens of rpm. It takes hours to hundreds of hours. Further, when processing the surface of the quartz base plate into a convex shape with such an apparatus, it is necessary to put the quartz base plate into the container in units of thousands, which makes it difficult to cope with a small lot. Furthermore, since the surface polishing state of each quartz base plate in the polishing container cannot be controlled and managed, the surface shape varies within the input lot. In addition, it is necessary to control the amount of abrasives introduced and the temperature and humidity during polishing.

  In order to solve the above-mentioned problems, in the present invention, an excitation electrode formed on the front and back main surfaces of the crystal base plate so as to face each other between the front and back main surfaces, and the excitation electrode, A quartz resonator element in which a lead electrode extending from an electrode to an outer edge portion of the quartz base plate is formed, and at least one circular or arc-shaped groove portion concentric with the center of the excitation electrode is provided. It is formed in the main surface of this crystal vibration element characterized by the above-mentioned.

  Also, an excitation electrode formed on a crystal element plate having a flat outer shape on the front and back main surfaces of the crystal element plate so as to face each other between the front and back main surfaces, and from the excitation electrode to the outer edge of the crystal element plate In the method for manufacturing a crystal resonator element that forms an extended lead electrode, at least one or more circular or arc-shaped groove portions concentric with the center of the excitation electrode are formed on the main surface of the crystal base plate. A method of manufacturing a quartz crystal vibrating element, characterized by being formed by a spindle means.

  With such a crystal resonator element and its manufacturing method, the crystal impedance is reduced by reducing the energy loss due to sub-vibration such as contour vibration and the energy confinement effect equivalent to that of a conventional crystal oscillator with convex processing. Various characteristics such as (hereinafter referred to as CI) and Q value can be improved. In addition, the introduction of large-scale equipment as in the prior art can be avoided, and furthermore, the same equipment can be used to manufacture crystal resonator elements from small to many types to large and small types, greatly reducing the cost of manufacturing quartz base plates. be able to.

  Furthermore, in the present invention, since the ultrasonic spindle processing means is used for forming the groove, the groove can be processed in about several seconds, so that the processing time can be greatly shortened compared to conventional convex processing, beveling processing or etching processing. Become. In addition, since the flat portion of the surface of the crystal base plate on which the excitation electrode is formed can be determined by the diameter of the cup wheel of the ultrasonic spindle, a plurality of crystal base plates having the same surface shape can always be formed. In addition, even in a crystal resonator element in which the surface of the quartz base plate is polished (cannot be converted), the same characteristics as the crystal resonator element subjected to the convex processing can be obtained by forming a groove on the surface.

  Due to the above-described operation, the quartz resonator element and the manufacturing method thereof according to the present invention are efficient and the same as the improvement in characteristics by the conventional convex shape in the same process regardless of the number of small-sized and large numbers of quartz base plates. Thus, the characteristics can be improved, and therefore, an effect of providing a crystal resonator element using a quartz base plate at low cost with high productivity is achieved.

The present invention will be described below with reference to the drawings.
1A and 1B are external views showing one embodiment of a crystal resonator element according to the present invention, wherein FIG. 1A is a plan view illustrating the main surface of the crystal resonator element, and FIG. 1B is a virtual cut described in FIG. It is sectional drawing at the time of cut | disconnecting by line A1-A2. FIG. 2 is a cross-sectional view of a crystal resonator element having the same outer shape as that of the crystal resonator element illustrated in FIG. 1 in which another form of groove is formed. FIG. 3 is a plan view showing another embodiment of the crystal resonator element according to the invention. In each drawing, the same reference numerals indicate the same object, and for the sake of clarity, a part of the structure that does not need to be described is not shown, and the dimensions of each structure are partially exaggerated. In particular, the thickness dimension of each structure is greatly exaggerated.

  In FIG. 1, a quartz base plate 11 is shown which is cut out from an artificial crystalline lens constituting a quartz resonator element 10 at a desired cut angle, is processed into a circular shape, and is further polished on both the front and back main surfaces. The quartz base plate 11 has a plurality of grooves 12 (four on the front and back sides in FIG. 1) concentrically with the center of a substantially circular excitation electrode 13 to be described later. It is formed on the front and back main surfaces of the quartz base plate 11 between the outer edges of the plate 11. By forming the groove 12 so as to be concentric with the center of the excitation electrode 13, the energy confinement effect generated in the excitation electrode 13 portion can be further enhanced.

  The groove portion 11 is formed by ultrasonic spindle processing means on the crystal base plate 11 that has been subjected to outer shape processing and surface polishing processing. That is, a cup wheel having a desired groove 12 diameter provided in the spindle processing apparatus is ultrasonically vibrated, and the cup wheel is brought into pressure contact with a predetermined position of the main surface of the crystal base plate 11 to grind the crystal crystal on the main surface. Thus, the groove portion 12 is formed. When a plurality of groove portions 12 are formed, the groove portions 12 are formed by using a cup wheel having a diameter that matches a desired diameter of each groove portion 12. The number of grooves 12 to be formed is increased or decreased according to desired vibration characteristics such as the resonance frequency value of the quartz crystal vibrating plate 10 (proportional to the thickness of the quartz vibrating plate 10 in the thickness-shear vibration mode), Q value, and CI value. . Moreover, as a processing speed, the time required to form one groove part with a depth of about 20 μm to 30 μm is about 1 second. Furthermore, processing with a processing surface accuracy of about 1 μm is possible.

  Depending on the desired vibration characteristics, various changes can be made by changing the groove cross-sectional shape of the groove 12 as shown in FIG. The cross-sectional shape of the groove 11 can be varied depending on the shape of the tip grindstone of the cup wheel. 1 and FIG. 2 disclose a structure in which the groove 12 is formed on the front and back main surfaces of the crystal base plate 11, but the effect of the present invention can be achieved even when the groove 12 is formed on only one of the main surfaces. It is possible to play.

  An excitation electrode 13 is formed in the excitation electrode forming regions on both the front and back main surfaces inside the innermost groove portion on the crystal base plate 11 in which the groove portion 12 is formed, and the outer edge of the crystal base plate 11 is formed from the excitation electrode 13. The crystal vibrating base plate 10 is formed by forming the extraction electrode 14 across the groove 12 in directions different from each other by 180 degrees toward the surface.

  By using the crystal resonator element 10 having such a surface shape, the CI value can be reduced by reducing the energy confinement effect equivalent to the crystal resonator element subjected to the conventional beveling process and the convex process and the vibration loss due to the secondary vibration such as the contour vibration. And various characteristics such as Q value can be improved. Further, in the present invention, since the ultrasonic spindle machining means is used to form the groove portion 12, the groove portion 12 can be machined in about several seconds, so that the machining time can be greatly reduced as compared with conventional beveling and convex machining. . Further, since the flat portion of the surface of the crystal base plate 10 on which the excitation electrode 13 is formed can be determined to have a fixed shape by the cup wheel having the smallest diameter used in the ultrasonic spindle, a plurality of crystal base plates 11 having the same surface shape are always provided. Can be formed. Further, even in the crystal resonator element 10 in which the surface of the crystal base plate 11 is polished (beveling or convex processing is not possible), the groove 12 is formed on the surface after the polishing, so that the beveling processing or the convex processing is performed. The same characteristics as the applied crystal resonator element can be obtained.

  FIG. 3 shows a form in which the groove 32 is formed in the crystal resonator element 30 constituted by the crystal base plate 31 having a rectangular outer shape. In the case of the rectangular crystal resonator element 30, the excitation electrode 33 is similar to the outer shape and is substantially rectangular, and there is not much difference between the width dimension of the quartz base plate 31 and the width dimension of the excitation electrode 33. The shape 32 is an arc shape concentric with the center of the excitation electrode 33.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

1A and 1B are external views showing one embodiment of a crystal resonator element according to the present invention, wherein FIG. 1A is a plan view illustrating the main surface of the crystal resonator element, and FIG. 1B is a virtual cut described in FIG. It is sectional drawing at the time of cut | disconnecting by line A1-A2. FIG. 2 is a cross-sectional view of a crystal resonator element having the same outer shape as that of the crystal resonator element illustrated in FIG. 1 in which another form of groove is formed. FIG. 3 is a plan view showing another embodiment of the crystal resonator element according to the invention. 4A and 4B are external views showing a conventional crystal processing element subjected to convex processing, where FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along a virtual cutting line B1-B2 described in FIG. It is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 ... Quartz vibration element 11, 31 ... Crystal base plate 12, 32 ... Groove part 13, 33 ... Excitation electrode 14, 34 ... Extraction electrode

Claims (2)

Excitation electrode formed on the front and back main surfaces of the crystal base plate with a flat outer shape on the front and back main surfaces, and extending from the excitation electrode to the outer edge of the crystal base plate In the crystal resonator element formed with the extracted electrode,
A quartz crystal resonator element, wherein at least one circular or arc-shaped groove portion concentric with the center of the excitation electrode is formed on the main surface of the quartz base plate. An excitation electrode formed on a crystal base plate having a flat outer shape on the front and back main surfaces of the crystal base plate so as to face each other between the front and back main surfaces, and extending from the excitation electrode to the outer edge of the crystal base plate In the manufacturing method of the crystal resonator element for forming the extracted electrode,
A method of manufacturing a crystal resonator element, wherein at least one or more circular or arcuate grooves having concentric centers of the excitation electrodes are formed on the main surface of the crystal base plate by an ultrasonic spindle means.

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