JP2013093797A - Crystal vibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal vibration device that facilitates high frequency and downsizing of a crystal diaphragm and improves shock resistance performance.SOLUTION: A crystal vibration device includes an AT-cut rectangular crystal diaphragm 1. On the principal plane of the crystal diaphragm, excitation electrodes 2 and 3 and extraction electrodes 4 and 5 that are made to extend to part of a side in a Z' axis direction in the outer peripheral end of the principal plane of the crystal diaphragm from the excitation electrode, are formed. On at least sides in an X-axis direction in the outer peripheral end of the principal plane of the crystal diaphragm, thick wall parts 111 and 131 composed of a metal film are provided. On at least a side in a Z'-axis direction in the outer peripheral end of the principal plane of the crystal diaphragm from which the extraction electrode is extended, a thick wall part 121 composed of a quartz base material is provided.

Description

  The present invention relates to a crystal vibration device, and relates to the structure of an AT-cut crystal vibration device.

  A crystal resonator using a thickness vibration type AT-cut crystal diaphragm generally has a configuration in which a pair of excitation electrodes are formed opposite to each other on the front and back surfaces of a crystal diaphragm and an AC voltage is applied to the excitation electrodes. The vibration frequency of such a crystal resonator depends on the thickness of the crystal diaphragm. For this reason, as a high-frequency quartz crystal plate that operates at a frequency of 100 MHz or more (16.7 μm or less) with a thickness-shear fundamental wave vibration, the central portion of the quartz crystal plate is recessed using a photolithographic technique and a wet etching technique. A so-called inverted mesa-shaped crystal diaphragm is formed in which a thin vibration region is formed and a thick frame region is formed at the peripheral edge.

  A quartz crystal plate made of an anisotropic crystal has different etching rates depending on the wet etching direction (quartz crystal axis). For example, in an AT-cut quartz diaphragm, a new axis that is shifted by θ ° from the Z axis is referred to as Z ′, and a new axis that is shifted from the Y axis by θ ° is referred to as Y ′. , Z ′> + X> −X> Y ′. For this reason, when the crystal diaphragm is wet etched to obtain an inverted mesa shape, the inclination angle of the stepped portion of the recess differs depending on the direction of the crystal diaphragm (crystal crystal axis). If they are mixed and the slope is large, the flat area of the vibration part is infringed. As a result, there arises a problem that it is impossible to secure an effective area of the vibration part region for the initial design. In particular, the miniaturized quartz diaphragm has such a problem, and the protruding portion of the slope is larger at the step portion of the thick portion at the outer peripheral end along the X-axis direction. Under the present circumstances, it is difficult to secure the vibration part due to the adverse effects of the above.

  In order to solve such problems, for example, Patent Document 1 proposes a thick frame region having a substantially L shape or I shape.

JP 2002-33640 A

  In the above-mentioned Patent Document 1, there is a large problem that the strength as a crystal diaphragm is insufficient, and a new problem arises that the impact resistance performance is poor.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a crystal resonator device that facilitates high frequency and miniaturization of the crystal diaphragm and has improved impact resistance. It is intended.

  Accordingly, in the quartz crystal vibrating device of the present invention, as shown in claim 1, there is an AT-cut rectangular quartz crystal vibrating plate, an excitation electrode on the main surface, and the main surface of the quartz crystal plate from the excitation electrode. A quartz-crystal vibrating device in which an extraction electrode extending to a part of a side in the Z′-axis direction among the outer peripheral ends is formed, and at least in a side in the X-axis direction among the outer peripheral ends of the main surface of the crystal vibrating plate And a thickened portion made of a metal film, and at least a side in the Z′-axis direction of an outer peripheral end portion of the main surface of the crystal diaphragm, and a side where the extraction electrode is extended has a crystal mother It has the thick part which consists of material, It is characterized by the above-mentioned.

  With the above configuration, at least one side in the X-axis direction of the outer peripheral end portion of the main surface of the quartz crystal plate has a thick portion made of a metal film. Even if the vibration region is made thinner, it is possible to constitute the end portion reinforcing portion of the crystal diaphragm having a small bank width. In particular, since the slope is formed relatively large in the step portion in the thick portion made of the crystal base material formed by wet etching the side in the X-axis direction of the crystal plate, the crystal plate is centered on the Z′-axis direction. However, in the present invention, since the slope is not formed in the thick portion made of the metal film, it is small without invading the vibration region of the crystal plate in the Z′-axis direction. It can also be adapted. In addition, by forming the thick part with a metal film that is separate from the crystal diaphragm, the entire thickness of the crystal diaphragm as the vibration part can be processed uniformly and is not easily affected by processing variations.

  In addition, at least a side in the Z′-axis direction of the outer peripheral end portion of the main surface of the crystal diaphragm and a side where the extraction electrode is extended have a thick portion made of a crystal base material. Therefore, even if the vibration region of the crystal diaphragm is thinned, a thick part made of a crystal base material can be configured as an end reinforcement on the side in the Z′-axis direction where the slope is difficult to be formed. It does not narrow the vibration area. In addition, by configuring a non-metallic thick portion made of a quartz base material, an extraction electrode can be formed on the upper portion of the non-metallic thick portion, so compared to a thick portion composed of a metal film. Thus, the extending direction of the extraction electrode is not hindered and can be held by a stable thick portion (end reinforcing portion) that can be formed thicker and wider. Furthermore, since the extraction electrode is extended at the side in the Z′-axis direction where the slope is difficult to be formed, the influence of the disconnection of the step portion between the vibration region and the thick portion is small.

  In addition, the thickness of the outer peripheral end of the quartz crystal plate is reduced by combining the thick portion made of the metal film and the thick portion made of the crystal base material as in the present invention. Even so, securing the vibration region and improving the strength of the end can be realized at the same time, and creation is also easy.

  The present invention can provide a crystal vibration device that facilitates high-frequency and miniaturization of a crystal diaphragm and has improved impact resistance.

The top view which shows the 1st Embodiment of this invention. Sectional drawing along the AA line of FIG. Sectional drawing along the BB line of FIG. The top view which shows the 2nd Embodiment of this invention. Sectional drawing along CC line of FIG. Sectional drawing along the DD line | wire of FIG. The top view which shows the modification of this invention. The top view which shows the other modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a crystal resonator (crystal resonator device) as an example. 1 is a plan view of a quartz crystal diaphragm according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is taken along line BB in FIG. FIG.

  The quartz crystal plate 1 is formed of an AT-cut quartz plate made of thickness shear vibration. For example, the X axis of the crystal crystal axis is substantially parallel to the long sides 11 and 13, and the Z ′ axis of the crystal crystal axis is the short sides 12 and 14. Are formed in a rectangular shape in a plan view so as to be substantially parallel to.

  A vibration region is provided at the center of the main surface of the quartz crystal plate 1, and excitation electrodes 2 and 3 having a substantially square shape in plan view are formed on the front and back surfaces thereof. This vibration region is configured as a high-frequency crystal diaphragm that operates at a frequency of 100 MHz or more with a thickness-shear fundamental wave vibration. In this embodiment, for example, the fundamental wave vibration is formed in the 98 to 110 MHz band and the vibration region has a thickness of about 15 to 17 μm.

  The excitation electrodes 2 and 3 have the same shape and the same area, and are formed to face each other with the crystal vibrating plate 1 therebetween. Since the excitation electrodes 2 and 3 have a square shape, the excitation electrodes 2 and 3 have two parallel sides and are formed in the same shape, and each parallel side extends along both the X-axis direction and the Z′-axis direction of the crystal diaphragm 1. Is formed. Lead electrodes 4, 5 extending from the respective excitation electrodes 2, 3 to the short side 12 in the Z′-axis direction of the outer peripheral end portion of the main surface of the crystal plate 1 are formed. These excitation electrodes and extraction electrodes have a structure in which an upper electrode layer such as gold (Au) is laminated on a base electrode layer of, for example, chromium (Cr) or nickel (Ni), and is formed by vacuum deposition or sputtering. However, it is not limited to the metal material.

  A thick frame region is formed around the main surface of the crystal diaphragm 1 (outer peripheral end), and a short side 12 of the crystal crystal axis in the Z′-axis direction is a thick portion 121 made of a crystal base material. Except for the region of the thick part 121, the long sides 11 and 13 of the X-axis of the crystal crystal axis have thick parts 111 and 131 made of a metal film.

  In the first embodiment of the present invention, as shown in FIGS. 2 and 3, each thick portion is formed only on the main surface side (the main surface on the upper side in the drawing) on which the excitation electrode 2 of the crystal diaphragm is formed. 111, 121, 131 are formed. That is, by using a photolithographic technique and a wet etching technique, only the main surface side (the main surface on the upper side in the figure) on which the excitation electrode 2 of the crystal diaphragm is formed, the portion excluding the region of the short side 12 is recessed. Thus, by forming a thin vibration region, a crystal base material in which the region of the short side 12 on the main surface side (upper main surface in the figure) where the excitation electrode 2 of the crystal vibration plate is formed protrudes. A thick part 121 is formed. Further, by using a technique such as a photolithography technique and electrolytic plating, only the main surface side (the main surface on the upper side in the figure) on which the excitation electrode 2 of the quartz crystal plate is formed, the length excluding the region of the thick portion 121. By forming a metal film in the regions of the sides 11 and 13, the regions of the long sides 11 and 13 on the main surface side (the main surface on the upper side in the figure) on which the excitation electrode 2 of the crystal diaphragm is formed protruded. Thick portions 111 and 131 made of metal plating are formed.

  The thick portions 111 and 131 are made of a material similar to that of the excitation electrode and the extraction electrode as a base electrode, and a metal film such as gold (Au) is formed thereon. The material of the metal film is not limited to the metal material, and an optimum material can be selected in consideration of cost and characteristics. In this embodiment, the gold-plated metal film is formed by electrolytic plating, but the metal film may be formed by other methods such as non-electrolytic plating, vacuum deposition, and sputtering. By adopting a plating method, a thick metal film can be formed at a lower cost.

  Next, a second embodiment of the present invention will be described with reference to the drawings, taking a crystal resonator (crystal resonator device) as an example. 4 is a plan view of a quartz crystal diaphragm according to a second embodiment of the present invention, FIG. 5 is a cross-sectional view taken along line CC in FIG. 4, and FIG. 6 is taken along line DD in FIG. FIG. Note that portions similar to those in the first embodiment described above are denoted by the same reference numerals, and a part of the description is omitted.

  The vibration region of the quartz diaphragm according to the second embodiment of the present invention is formed with, for example, a 555 to 835 MHz band for fundamental wave vibration and a thickness of the vibration region of about 2 to 3 μm. Similarly, a thick frame region is provided around the main surface of the crystal diaphragm 1 (outer peripheral end). The short side 12 of the crystal crystal axis in the Z′-axis direction has thick portions 121 and 122 made of a crystal base material, and the short side 14 of the crystal crystal axis in the Z′-axis direction has a crystal base material. It has the thick parts 141 and 142 which consist of. Except for the regions of the thick portions 121, 122, 141, 142, the long side 11 of the X-axis of the crystal crystal axis has thick portions 111, 112 made of a metal film. The long side 13 of the X axis of the crystal axis has thick portions 131 and 132 made of a metal film.

  In the second embodiment of the present invention, unlike the first embodiment, as shown in FIGS. 5 and 6, the thick portions 111, 112, 121, 122, 131 are formed on both main surfaces of the crystal diaphragm. , 132, 141, 142 are formed. In other words, by using a photolithographic technique and a wet etching technique, a portion of the quartz diaphragm excluding the area of the short side 12 is recessed from both principal face sides to form a thin vibrating area, whereby both quartz crystal diaphragms Thick portions 121 and 122 made of a crystal base material from which the region of the short side 12 of the surface protrudes are formed. Further, by using a technique such as photolithography and electrolytic plating, a metal film is formed on the long sides 11, 13 and 14 except for the thick portions 121 and 122 on both main surfaces of the quartz diaphragm. Thick portions 111, 112, 131, 132, 141, 142 made of a metal film in which the regions of the long sides 11, 13 on both main surface sides (upper main surface in the drawing) of the crystal diaphragm are formed are formed. doing.

  The thick portions 111, 112, 131, 132, 141, and 142 are made of a material similar to that of the excitation electrode and the extraction electrode as a base electrode, and a metal film such as gold (Au) is formed thereon. The material of the metal film is not limited to the metal material, and an optimum material can be selected in consideration of cost and characteristics.

  The quartz diaphragm 1 according to the first and second embodiments configured as described above is housed in a package body such as ceramic or glass (not shown), and the quartz diaphragm 1 is mounted on the package body with a conductive resin. Electromechanical bonding is performed by an adhesive, a conductive bonding material such as a metal bump or a plating bump. Then, after performing a stabilization process by a predetermined heating or the like, the opening of the package body is hermetically sealed by means such as seam bonding, beam bonding, brazing bonding, or glass sealing with a lid (not shown). The crystal unit is completed.

The present invention is not limited to the embodiment as described above, and may be as shown in FIGS.
In the modification of FIG. 7, the thick portion 121 made of a crystal base material and the thick portions 111 and 131 made of a metal film are formed around the main surface (outer peripheral end portion) of the crystal diaphragm 1 as in the above-described embodiment. , 141, a non-thick part M is formed in which one or more metal films are not formed in some side regions. This modification is effective in reducing the stress of the metal film.

  In another modification of FIG. 8, thick portions 121 and 141 made of a crystal base material are formed on two opposite sides 12 and 14 in the Z′-axis direction of the outer peripheral end of the main surface of the crystal diaphragm 1, Except for the areas of the thick portions 121 and 141, the long sides 11 and 13 of the X axis are formed with thick portions 111 and 131 made of a metal film. In the present modification, the thickness of the thick portion 121 and the thick portion 141 made of a crystal base material can be configured in the same manner, so that the mounting stability can be enhanced.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to crystal vibration devices such as crystal resonators.

1 Quartz diaphragm 2, 3 Excitation electrode 4, 5 Extraction electrode

Claims (1)

There is an AT-cut rectangular crystal diaphragm, an excitation electrode on its main surface, and a lead extending from the excitation electrode to a part of the Z′-axis side of the outer peripheral edge of the main surface of the crystal diaphragm A quartz-crystal vibrating device in which an electrode is formed, and has a thick portion made of a metal film on at least a side in an X-axis direction of an outer peripheral end portion of the main surface of the quartz-crystal vibrating plate, A quartz-crystal vibrating device having a thick portion made of a quartz base material on at least the side in the Z′-axis direction of the outer peripheral end portion of the main surface and the extended side of the extraction electrode.

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