JP2007013571A - Manufacturing method of piezoelectric base plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that since a conventional manufacturing method of the piezoelectric base plate is provided with a process in which specular working is applied to a piezoelectric base plate surface, beveling polishing of relatively coarse abrasive particles is applied, and a main surface shape of the piezoelectric base plate is gradually approximated to a convex shape, unnecessary scratch is generated on the piezoelectric base plate surface by polishing the piezoelectric base plate surface subjected to specular finishing, with coarse abrasive particles. <P>SOLUTION: The manufacturing method of the piezoelectric base plate is provided with: a process for apply polishing to both sides of the main surfaces of the piezoelectric base plate until it has a specific thickness according to a lapping polishing method; a process for applying beveling machining to a main surface edge part of the piezoelectric base plate; a process for applying the specular finishing to the main surfaces of the piezoelectric base plate by the polishing; a process for applying coarse polishing to one of the main surfaces of the piezoelectric base plate so that it becomes almost a convex shape; and a process for applying the specular finishing to the main surfaces processed to have an almost convex shape of the piezoelectric base plate so that they are in desired convex shapes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric element plate, and more particularly, to a method for manufacturing a piezoelectric element plate having a good manufacturing yield when the outer shape of the piezoelectric element plate is processed into a convex shape.

  As one of the piezoelectric element plates, a crystal element plate having a disk shape or a rectangular shape is usually used for a crystal diaphragm such as an AT cut used for a thickness-shear crystal resonator. Quartz crystals used in crystal resonators with a relatively low vibration frequency (10 MHz or less) and crystal resonators that require high stability can further improve the energy confinement effect, and can be caused by sub-vibration such as contour vibration. In order to improve various characteristics such as crystal impedance (hereinafter referred to as CI) and Q value by reducing vibration loss, the outer shape is a convex shape. Note that a quartz base plate formed by SC cut is used for a quartz resonator that requires higher stability.

  As a manufacturing method for finally converting the outer shape of a crystal element plate, which is one of piezoelectric element plates, into a convex shape, a processing method by polishing has been employed. For example, after the main surface of a quartz base plate that has been externally processed into a flat plate shape is polished to a predetermined thickness by a lapping polishing method, the surface of the quartz base plate is processed into a mirror surface by polishing.

  Next, the mirror-finished quartz base plate is beveled, and the edge of the main surface of the quartz base plate is processed to be thinner than the center of the main surface. A rough polishing process is applied to a shape similar to a desired convex shape. Then, the main surface of the quartz base plate that has been subjected to temporary convex shape processing 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 to change the curvature of the inner wall to the quartz base plate. A manufacturing method that obtains a convex shape by polishing so as to be copied onto the main surface, or a plate having a spherical surface, and applying a polishing material to this surface and sliding it while pressing the quartz base plate, the plate surface A method of obtaining a convex shape by transferring the curvature of the above to a quartz base plate is used.

  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.

  The following literature is disclosed about the manufacturing method of the above piezoelectric element plates (crystal element plates).

JP-A-2-205466 JP 2001-1249 A Supervised by Sadao Taki, "Artificial Quartz and its Electrical Applications", published by Nikkan Kogyo Shimbun, published May 30, 1974, p. 96-102

  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.

  However, in the method of manufacturing a piezoelectric element plate as described above, since the surface of the piezoelectric element plate is processed into a mirror surface by polishing in a flat plate form, the beveling process is performed. The surface of the piezoelectric base plate that had been mirror-finished was roughened because it was equipped with a process of gradually bringing the shape of the main surface of the piezoelectric base plate closer to the convex shape by beveling polishing using an abrasive. By polishing with, there is a possibility that unnecessary scratches may occur on the surface of the piezoelectric base plate.

  When a piezoelectric element plate having scratches on its surface is formed on a piezoelectric diaphragm and mounted on a piezoelectric vibrator, the crystal impedance value (hereinafter referred to as CI value), frequency temperature characteristics, etc. as the piezoelectric vibrator are affected by the scratches. In some cases, a problem may occur in the piezoelectric vibration characteristics, and the product yield as a piezoelectric vibrator may be deteriorated. Also, the characteristics themselves are unstable.

The present invention has been made in view of the above-described problems of the prior art, and is a method for manufacturing a piezoelectric element plate in which the shape of the main surface of a piezoelectric element plate subjected to external processing is formed into a substantially convex convex shape. In the method
Polishing the front and back main surfaces of the piezoelectric base plate to a predetermined thickness by a lapping polishing method;
The beveling process is performed on the main surface edge of the piezoelectric element plate, and the main surface edge is processed so that the thickness is gradually thinner than the main surface center.
A step of mirror-finishing the main surface of this piezoelectric base plate by polishing,
A step of rough polishing so that at least one main surface of the piezoelectric element plate has a substantially convex shape;
And a step of mirror-finishing the principal surface of the piezoelectric element plate that has been processed into a substantially convex shape so as to have a desired convex shape.

  By using such a method for manufacturing a piezoelectric element plate, it is possible to prevent generation of scratches on the surface of the piezoelectric element plate that has occurred when the conventional manufacturing method is used. Such a piezoelectric element plate is used for a piezoelectric vibrator. In this case, defects in the piezoelectric vibration characteristics due to scratches can be eliminated, and the characteristics themselves are very stable, so that the product yield as a piezoelectric vibrator can be improved.

  Therefore, by using the manufacturing method according to the present invention, it is possible to provide a piezoelectric element plate that can constitute a piezoelectric vibrator that is inexpensive and has good productivity.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram illustrating an outline of a manufacturing process exemplifying a quartz element plate using quartz crystal, which is one of piezoelectric materials, as the piezoelectric element plate according to the present invention. In FIGS. 1 and 2, a part of the structure is not shown for clarity of explanation, and some dimensions are exaggerated.

  That is, in FIG. 1A, first, the front and back main surfaces of the crystal base plate 11 that has been processed into a flat plate shape are polished to a predetermined thickness by lapping polishing. In this embodiment, the quartz base plate 11 formed by SC cut from an artificial crystalline lens is used, but other cut angles (for example, AT cut) may be used depending on conditions such as a desired standard.

  Next, in FIG. 1B, the main surface edge of the quartz base plate 11 is beveled, and the thickness of the main surface edge is gradually thinner than that of the main surface center. To process. This beveling process can be roughly divided into two methods. One is to apply a polishing material to a plate having a spherical surface, and slide the quartz base plate 11 while pressing it to change the curvature of the plate surface. A method of polishing so as to transfer to 11 and the other using a barrel polishing machine, a plurality of quartz base plates 11 and abrasives are put into a cylindrical or spherical processing apparatus, and the processing apparatus is The surface of the quartz base plate 11 is processed by revolving. The abrasive material used at this time is an extremely coarse abrasive material as compared with the abrasive used in other steps.

  Next, in FIG.1 (c), the main surface of the quartz base plate 11 by which the beveling process was given to the surface is mirror-finished by polishing process. By this step, the work-affected layer and scratches formed on the surface of the crystal base plate by the lapping and beveling processing steps of the previous step are removed by polishing, so that the surface state of the crystal base plate 11 becomes a stable mirror surface state.

  Next, in FIG. 1D, rough polishing is performed so that one main surface of the polished quartz base plate 11 has a substantially convex shape. Thus, by processing one main surface of the quartz base plate 11 to a shape similar to a desired convex shape in advance, the time required for convex polishing according to the next step can be shortened. Incidentally, the other principal surface of the quartz base plate not subjected to the rough polishing is kept in a mirror state.

  Next, in FIG.1 (e), the mirror surface processing is performed so that the main surface processed into the general convex shape of this quartz base plate 11 may become a desired convex shape. In this embodiment, a plate having a spherical surface is used, an abrasive is applied to the plate surface, the quartz base plate 11 is slid while being pressed, and the curvature of the plate surface is transferred to the main surface of the quartz base plate 11. And a method for obtaining a convex shape is used. There are several other methods for making the principal surface of the quartz base plate 11 into a convex shape, but the present invention is effective even when these existing methods are used. Further, at the end of each step described above, the surface of the quartz base plate 11 is cleaned with pure water or the like.

  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. For example, in this embodiment, the best mode of the present invention has been described by exemplifying a crystal base plate using quartz as a material of the piezoelectric base plate. However, as a piezoelectric material in which the present invention is effective, in addition to crystal, tantalate Examples include lithium, lithium niobate, and piezoelectric ceramics.

FIG. 1 is a schematic process diagram illustrating a manufacturing method according to the present invention using a quartz element plate which is one of piezoelectric element plates.

Explanation of symbols

  11 ... Crystal blank (piezoelectric blank)

Claims (1)

In the manufacturing method of the piezoelectric element plate, the shape of the main surface of the piezoelectric element plate subjected to the outer shape processing is formed into a substantially convex convex shape.
Polishing the front and back main surfaces of the piezoelectric base plate to a predetermined thickness by a lapping polishing method;
Beveling the main surface edge of the piezoelectric element plate, and processing the main surface edge to be thinner than the main surface center; and
A step of polishing the principal surface of the piezoelectric base plate by polishing;
A step of rough polishing so that at least one main surface of the piezoelectric element plate has a substantially convex shape;
And a step of subjecting the principal surface of the piezoelectric element plate processed into a substantially convex shape to mirror finishing so as to have a desired convex shape.

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