JP2006261746A - Method of manufacturing piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezoelectric vibrator which reduces manufacturing cost by improving the productivity and yield in manufacturing the piezoelectric vibrator. <P>SOLUTION: The piezoelectric vibrator has been manufactured by a process of cleaning a piezoelectric blank plate; process of vapor-depositing an excitation electrode on the main surface of the blank plate after cleaning; process of adjusting the thickness of the metal electrode provided on the piezoelectric blank plate; process of dividing the piezoelectric blank plate into singular pieces after adjusting the thickness of the metal electrode to form piezoelectric vibration pieces; process of mounting each of the piezoelectric vibration pieces on a package for piezoelectric vibrator via a conductive adhesive; process of drying the conductive adhesive after mounting; and process of minutely adjusting the main vibration frequency of each of the piezoelectric vibrators after drying. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrator having excellent productivity and reduced manufacturing costs.

  Conventionally, electronic parts having functions such as frequency generation sources and filters have been made using piezoelectric materials. Among various piezoelectric materials, piezoelectric vibrators (quartz crystal vibrators) that use quartz that has particularly excellent resonance characteristics are widely used. Has been. Crystal resonators are mounted on OA devices such as computers and mobile communication devices represented by mobile phones, and there is an increasing demand for crystal resonators that are inexpensive and have good frequency characteristics.

  A method for manufacturing such a crystal unit will be described with reference to the flowchart of FIG. First, a quartz wafer (base plate) cut out from a quartz crystal is polished to a required external dimension and thickness and cleaned (M30). After cleaning, an electrode made of a metal material such as Au or Al for exciting the crystal base plate is deposited on the main surface of the crystal base plate in a predetermined electrode shape to form a metal electrode film. (M31). After the metal electrode film is formed, the crystal base plate is divided into individual pieces by a dicing saw or the like, and a crystal vibrating piece in which the metal electrode film is formed on each crystal piece is formed (M32). . Thereafter, the crystal vibrating piece is mounted on a package for housing the crystal vibrating piece via a conductive adhesive (M33), and the conductive adhesive is cured by a drying (annealing) process (M34). In order to obtain a target main vibration frequency by evaporating a further metal electrode on the metal electrode film or removing the metal electrode film by a technique such as etching after the conductive bonding time is cured. The frequency is finely adjusted (M35), and the inside of the package is sealed in a vacuum state to prevent the secular change caused by the chemical change of the electrode material and maintain stable performance, thereby completing the crystal resonator ( M36).

As a means for fine adjustment of the final main vibration frequency in the quartz crystal resonator element as described above, for example, JP-A-5-29864 is disclosed. The above publication is characterized in that a metal material thin film is formed on a vibrating electrode formed on the front and back surfaces of a piezoelectric substrate by a dry method (evaporation, sputtering, etc.) to a thickness corresponding to the frequency to be adjusted.
According to the publication, in a piezoelectric resonant element in which the vibration electrode is deposited on the piezoelectric substrate, when the resonance frequency is higher than the target frequency, the metal electrode is deposited on the vibration electrode so that the target frequency is obtained. When the resonance frequency of the piezoelectric resonator is lower than the target frequency, the electrode material on the vibrating electrode is removed by sputtering so that the resonance frequency becomes the target frequency. Since the film thickness can be accurately controlled, the resonance frequency can be adjusted with high accuracy, and the defective product occurrence rate can be greatly reduced.
JP-A-5-29864

However, the crystal resonator manufacturing method in the manufacturing process as described above has the following problems. After the crystal base plate is cut out from the crystal, the crystal base plate polished to the required outer dimensions and thickness has a thickness t1 at the center of the base plate as shown in FIG. 4 (a). Mainly, the shape becomes thicker than the thickness t2. Therefore, when a metal electrode is formed on the main surface of the base plate having a shape as shown in FIG. 4A, the crystal base plate after the metal electrode film formation is shown in FIG. The total thickness of the thickness and the metal electrode film thickness varies greatly between the central portion and the end portion (peripheral portion) of the quartz base plate. As is well known, the main vibration frequency of the crystal resonator depends on the total thickness of the crystal element plate thickness and the electrode film thickness. The frequency varies greatly. Accordingly, since the frequency fine adjustment step (M35) in FIG. 5 requires a large frequency adjustment, the deposition time of the metal electrode film becomes longer, which affects the productivity of the crystal unit. there were. In addition, there is a problem that it is difficult to reduce the manufacturing cost because the yield of the product is lowered due to the generation of the quartz crystal vibrating piece in which the frequency adjustment becomes impossible as the frequency adjustment amount increases.
It is an object of the present invention to provide a method for manufacturing a piezoelectric vibrator that improves the production time and yield in manufacturing the piezoelectric vibrator and reduces the manufacturing cost.

  To achieve the above object, the present invention provides a method for manufacturing a piezoelectric vibrator, a step of cleaning a piezoelectric element plate, a step of vapor-depositing a metal electrode on the main surface of the piezoelectric element plate after cleaning, Adjusting the thickness of the metal electrode provided on the piezoelectric element plate, dividing the piezoelectric element plate into pieces after adjusting the thickness of the metal electrode, and forming each piezoelectric vibrating piece; A step of mounting the piezoelectric vibrating piece on a package for a piezoelectric vibrator via a conductive adhesive, a step of drying the conductive adhesive after the mounting, and a fine adjustment of the main vibration frequency of the piezoelectric vibrating piece after the drying The piezoelectric vibrator is manufactured by the step of performing.

In the method for manufacturing a piezoelectric vibrator according to the present invention, since the process of adjusting the thickness of the metal electrode film is added after forming the metal electrode film on the main surface of the piezoelectric element plate, the piezoelectric element plate and the metal electrode are added. Since the total thickness with the film becomes substantially uniform and the time for fine frequency adjustment in the manufacturing process of the piezoelectric vibrator can be greatly shortened, the production speed of the piezoelectric vibrator can be improved. In addition, since the frequency adjustment amount at the time of fine frequency adjustment can be reduced, there is no possibility of producing a piezoelectric vibrating piece that cannot be adjusted, and the yield can be improved.
Due to the above-described effects of improving the production speed and improving the yield, it is possible to manufacture a piezoelectric vibrator with reduced manufacturing costs.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiment. In addition, about the structural member similar to what was shown in the above-mentioned prior art example, the same code | symbol is attached | subjected and the description is abbreviate | omitted. The manufacturing method for the crystal resonator of this example will be described by taking as an example a process for batch processing of crystal pieces in the state of a crystal base plate.

  FIG. 1 is a flowchart showing a manufacturing process of a crystal resonator according to an embodiment of the present invention. First, a quartz base plate cut out from a quartz crystal is polished to a required external dimension and thickness and washed (M30). As described above, the polished quartz base plate has a barrel-shaped shape in which the thickness t1 of the center portion of the base plate is thicker than the thickness t2 of the end portion of the base plate, as shown in FIG. It becomes.

  After the cleaning process, the quartz base plate is sandwiched between metal masks, and a metal electrode having a predetermined shape and film thickness is formed on both main surfaces of the quartz base plate. An electrode film made of a metal material such as Al is formed (M31). In addition, since the metal electrode film is formed on the crystal base plate 10 shown in FIG. 4 (a), the crystal base plate after the metal electrode film formation is shown in FIG. 4 (b). Regarding the thickness of 10 and the thickness and total thickness of the metal electrode film 11, the thickness at the center of the base plate is larger than the thickness at the end of the base plate.

After the formation of the metal electrode film, as shown in FIG. 2A, a hole is formed in the center so that the total thickness of the crystal element plate thickness and the metal electrode film thickness is uniform over the entire element plate. The metal mask 12 having 13 is placed on the upper surface of the quartz base plate 10 and dry etching is performed to scrape the metal electrode located at the center of the quartz base plate and adjust the thickness of the metal electrode film ( M41).
As described above, in the quartz base plate on which the metal electrode film is formed, the total thickness of the thickness of the quartz base plate and the thickness of the metal electrode film becomes thicker at the center portion of the base plate than at the end portion of the base plate. . Therefore, the total thickness of the crystal base plate and the metal electrode film is adjusted almost uniformly in the entire crystal base plate by cutting the metal electrode film at the center of the crystal base plate by the dry etching. It becomes possible.

After the thickness adjustment step of the metal electrode, the crystal base plate is divided into individual pieces by a dicing saw or the like, and each crystal vibrating piece is formed (M32).
The quartz crystal resonator element is accommodated in a quartz resonator package through a conductive adhesive by a mounting process (M33), and after passing through a drying (annealing) process of the conductive adhesive (M34), the excitation is performed. On the electrode film of the electrode, a fine metal electrode film is deposited, or the electrode film is removed by a technique such as etching or sputtering, thereby finely adjusting the frequency to obtain a target main vibration frequency ( M35). Since the thickness of each crystal vibrating piece is uniform by the metal electrode thickness adjusting step (M41), the frequency adjustment amount in the fine frequency adjustment step (M35) is the target main vibration depending on the minute adjustment amount. The frequency can be obtained.
After the fine frequency adjustment step, the package is sealed with a vacuum or nitrogen gas sealed in order to prevent aging caused by chemical changes in the electrode material and maintain stable performance. The child is completed (M36).

As described above, in the method for manufacturing a crystal resonator, the step of cleaning the crystal base plate, the step of forming a metal electrode film on the main surface of the crystal base plate after cleaning, and the metal electrode at a predetermined position About the step of cutting by dry etching and adjusting the thickness of the metal electrode, the step of dividing the crystal base plate into pieces after adjusting the thickness of the metal electrode, and forming each piece of crystal vibrating piece, and the crystal vibrating piece A step of mounting the quartz resonator package via a conductive adhesive, a step of drying the conductive adhesive after the mounting, and a step of finely adjusting the main vibration frequency of the crystal element after the drying. Since the quartz crystal unit is manufactured, the total thickness of the quartz base plate and the metal electrode film at each location after the thickness adjustment of the metal electrode is uniform, and the final fine frequency adjustment can be greatly reduced. Can be improved because, the production time of the crystal oscillator. Further, since the amount of adjustment during the fine frequency adjustment is reduced, there is no possibility of occurrence of an unadjustable crystal vibrating piece, so that the yield can be improved and the crystal resonator can be manufactured with reduced manufacturing costs.
In the above embodiment, the metal electrode film provided on the main surface of the crystal base plate is dry-etched so that the total thickness of the crystal base plate thickness and the thickness of the metal electrode film in each part of the crystal base plate is uniform. Although the thickness of the metal electrode film was adjusted by means of shaving, the same effect can be obtained if the metal electrode film is shaved by means such as sputtering or laser processing. In addition, as shown in FIG. 3, the metal electrode film is additionally formed only on an end portion (peripheral portion) of the crystal element plate by means such as vapor deposition, so that the entire crystal element plate is Even if the thickness of the metal electrode film is adjusted, the same effect is obtained.
Moreover, although the example of the crystal resonator has been described in the above embodiment, the present invention is not limited to this, and it is obvious that the present invention may be applied to a piezoelectric material other than the crystal.

It is a flowchart figure which shows the manufacturing process of the crystal oscillator based on this invention. (A) It is sectional drawing which shows the method of adjusting the thickness of the metal electrode film which concerns on this invention. (B) It is a perspective view which shows the method of adjusting the thickness of the metal electrode film which concerns on this invention. (A) It is sectional drawing which shows the modification in the method of adjusting the thickness of the metal electrode film which concerns on this invention. (B) It is a perspective view which shows the modification in the method of adjusting the thickness of the metal electrode film which concerns on this invention. (A) It is a figure which shows the quartz base plate cross section after the conventional quartz base plate grinding | polishing process. (B) It is a figure which shows the quartz base plate cross section after forming a metal electrode film in the conventional quartz base plate. It is a flowchart figure which shows the manufacturing process of the conventional crystal oscillator.

Explanation of symbols

10 Crystal base plate 11 Metal electrode 12 Metal mask 13 Hole

Claims (3)

  A step of cleaning the piezoelectric element plate, a step of depositing a metal electrode on the main surface of the piezoelectric element plate after the cleaning, a step of adjusting the thickness of the metal electrode after the metal electrode deposition step, After the thickness adjustment step, the piezoelectric element plate is divided into individual pieces to form a piezoelectric vibrating piece, the piezoelectric vibrating piece is mounted on a piezoelectric vibrator package via a conductive adhesive, and the mount A method of manufacturing a piezoelectric vibrator, comprising: a step of drying the conductive adhesive after the step; and a step of finely adjusting a main vibration frequency of the piezoelectric element after the drying.   2. The method of adjusting a thickness of the metal electrode, wherein the thickness of the metal electrode is adjusted by removing the metal electrode at a central portion of the piezoelectric element plate. Method. 2. The piezoelectric vibration according to claim 1, wherein the method for adjusting the thickness of the metal electrode includes adjusting the thickness of the metal electrode by adding a metal electrode to the periphery of the piezoelectric element plate. Child manufacturing method.

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