JP2012195711A - Crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator with excellent characteristics in which the effect of an unwanted mode is eliminated as much as possible.SOLUTION: A crystal diaphragm 1 is made of an AT-cut crystal diaphragm and comprises: a thin portion 10 which is rectangular in a plan view; and a thick portion 11 which is rectangular in a plan view and thicker than the thin portion 10. On both principal surfaces of the thick portion 11, excitation electrodes 12 and 13 are formed to face each other, and they are connected to connection electrodes 12b and 13b, respectively. The connection electrodes 12b and 13b are unevenly distributed at a corner C1 of the crystal diaphragm 1, while the thick portion 11 and the excitation electrodes 12 and 13 are unevenly distributed at a corner C2, with the former parts and the latter parts arranged to be spaced apart in a diagonal direction.

Description

  The present invention relates to a crystal resonator using thickness shear vibration used in electronic equipment.

  In the crystal resonator, suppression of unnecessary modes is important for ensuring desired characteristics. The unnecessary mode includes a vibration mode other than the main vibration, a harmonic vibration mode, or the like. However, a mesa configuration (a configuration having a thick portion) is disclosed for the purpose of suppressing such an unnecessary mode. An example of such a configuration is shown in Japanese Patent Application Laid-Open No. 2008-263387. In this configuration, a mesa-type piezoelectric diaphragm is disclosed in which a vibration part having a thickness dimension larger than that of the peripheral part is formed at the central portion of the plate surface of the piezoelectric diaphragm, and the piezoelectric diaphragm is held by one side with one side held Configuration is adopted.

JP 2008-263387 A

  In Patent Literature 1, unnecessary modes that may occur during driving are suppressed by specifying in relation to the amount of mesa excavation, but there are not a few from the mesa portion (thick portion) of the vibration region. The vibration sometimes propagated to the thin part. In such a case, when holding the quartz diaphragm (piezoelectric diaphragm) to the base or the like, the influence of the holding part may adversely affect the characteristics of the quartz diaphragm.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a crystal resonator having good characteristics in which the influence of an unnecessary mode is eliminated as much as possible even when it is miniaturized.

  A crystal resonator according to the present invention is made to achieve the above object, and has a rectangular crystal diaphragm including a thick portion, a thin portion, and a connection electrode connected to the outside by a conductive bonding material. The thick electrode is formed with the excitation electrode, and the excitation electrode is connected to the connection electrode, and the excitation electrode and the connection electrode are each arranged in a diagonally spaced manner in the diagonal direction of the crystal diaphragm. It is characterized by that.

  The region where the excitation electrode is formed vibrates more strongly than the surrounding area when the crystal resonator is driven, and even when the vibration energy is confined by the formation of the thick portion, vibration energy is generated in the thin portion. May propagate. The vibration energy is attenuated by separating the region where the excitation electrode is formed and the region where the connection electrode is formed diagonally, and the influence of the connection electrode joining, that is, the holding (adhering) of the crystal diaphragm is affected. It can be suppressed as much as possible.

In addition, a crystal resonator according to the present invention is made to achieve the above-described object, and has a crystal vibrating plate having a thick portion, a thin portion, and a connection electrode connected to the outside by a conductive bonding material. The thick electrode portion is formed with the excitation electrode, and the excitation electrode is connected to the connection electrode, and the thick wall portion and the connection electrode are each arranged in a diagonally spaced manner in the diagonal direction of the crystal diaphragm. It is characterized by being.

The excitation electrode formation region in the thick wall portion vibrates more strongly than the surrounding area when the crystal unit is driven, and even if the vibration energy is confined by the formation of the thick wall portion, the vibration energy is not contained in the thin wall portion. May propagate. By separating the thick-walled portion where the excitation electrode is formed and the region where the connection electrode is formed in a diagonal direction, the vibration energy is attenuated and the connection electrode is bonded, that is, the quartz diaphragm is held (adhered). Can be suppressed as much as possible.

In each of the above configurations, the conductive bonding material may be a metal bump, and the connection electrode may be electrically and mechanically connected to the outside by the metal bump.

The electrical / mechanical connection by the metal bumps can be performed with strong bonding by using FC bonding (flip chip bonding) using ultrasonic waves. Therefore, the conductive bonding by the metal bumps has an advantage of being stable. Yes. However, because of the strong bonding, the buffering function is small, for example, when vibration energy propagates, it cannot be absorbed sufficiently, and the characteristics of the crystal unit may fluctuate greatly due to the bonding. It was. According to this configuration, since the excitation electrode formation region and the connection electrode formation region to be driven are separated in the diagonal direction, it is possible to suppress the deterioration of the characteristics of the crystal resonator.

Moreover, in each said structure, the structure by which the taper is formed in the boundary of a thick part and a thin part may be sufficient.

The taper is an inclined part having a slope extending from the thick part to the thin part. By forming such a taper, the vibration of the thick part can be smoothly attenuated and propagated to the thin part and driven. Coupled with the fact that the excitation electrode formation region and the connection electrode formation region are diagonally separated, propagation of vibration energy to the connection electrode can be suppressed.

  Furthermore, in each of the above configurations, a protruding portion may be formed on one side or two sides adjacent to each other of the quartz crystal plate, and the connection electrode may be formed on the protruding portion.

With the above configuration, the projecting portion is formed so as to protrude outside the rectangular crystal diaphragm, and the connection electrode is formed on the projecting portion. For this reason, coupled with the fact that the excitation electrode formation region and the connection electrode formation region to be driven are spaced apart in the diagonal direction, the vibration of the thick portion is difficult to propagate through the connection electrode.

Further, in each of the above configurations, the connection electrodes are configured as a pair, each connection electrode is bonded to the outside by the conductive bonding material, and the outer size of the conductive bonding material close to the excitation electrode is far from the excitation electrode. The configuration may be smaller than the outer size of the conductive bonding material.

  As described above, the excitation electrode formation region vibrates more strongly than the surrounding area when the crystal resonator is driven, and even when the vibration energy is confined by the formation of the thick portion, vibration energy is generated in the thin portion. May propagate. This vibration energy is gradually attenuated and propagates. However, by setting the outer size of the conductive bonding material close to the excitation electrode to be smaller than the outer size of the conductive bonding material far from the excitation electrode, a relatively undamped region is reduced. By joining with a conductive bonding material of a size, vibration can be attenuated smoothly without hindering main vibration. Further, the bonding strength can be improved by increasing the outer size of the conductive bonding material far from the excitation electrode.

  According to the present invention, it is possible to obtain a crystal resonator having good characteristics in which the influence of an unnecessary mode is eliminated as much as possible even when it is miniaturized.

The perspective view of the quartz-crystal diaphragm which shows 1st Embodiment by this invention. Plan view of FIG. The figure which shows the state which airtightly accommodated the crystal diaphragm of AA sectional drawing of FIG. 2 in a package. Sectional drawing of the crystal diaphragm which shows 2nd Embodiment by this invention The top view of the quartz-crystal diaphragm which shows 3rd Embodiment by this invention. The top view of the crystal diaphragm which shows 4th Embodiment by this invention The top view of the quartz-crystal diaphragm which shows 5th Embodiment by this invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. 1 to 3 by taking a crystal resonator using an AT-cut crystal diaphragm as an example.

  As shown in FIG. 3, the crystal resonator has a structure in which a crystal diaphragm 1 is electrically and mechanically bonded to a base 2 by metal bumps 13 c and hermetically sealed by a lid 3.

  The quartz crystal plate 1 is composed of an AT-cut quartz plate and has a long side in the crystal axis X-axis direction, a short side in the Z-axis direction, and a thickness in the Y-axis direction. is there. Further, the quartz diaphragm has a thin portion 10 having a rectangular shape in plan view and a thick portion 11 having a rectangular shape in plan view, which is thicker than the thin portion 10. In this embodiment, the thick portion is formed inside the thin portion 10. It is a configuration. The thick portion has a long side and a short side, and is formed so as to be biased to one corner C2 of the quartz crystal plate 1. Specifically, one long side 11 a of the thick part is adjacent to one long side 1 a of the quartz crystal plate 1 in a parallel state, and one short side 11 b of the thick part is one short side of the crystal plate 1. It is the structure which adjoined in the state parallel to the edge | side 1b. The long side 1a and the long side 11a, and the short side 1b and the short side 11b may not be arranged in parallel. When not arranged in parallel as described above, for example, a vibration mode related to the contour system vibration may be suppressed.

  In the present embodiment, the thick part 11 has a thick structure (planomesa structure) in which the thickness of only one main surface of the crystal diaphragm 1 is increased as shown in FIG. In this case, since it is sufficient to form the thick portion only on one main surface, the manufacturing is easy, and there are advantages that the manufacturing error is small and the positioning of the energy confinement region is easy.

Moreover, the thick structure (bi-mesa structure) which thickness increased on both main surfaces (front and back) may be sufficient. In this case, the vibration energy confinement efficiency is improved, and a crystal resonator having good characteristics can be obtained.

Excitation electrodes 12 and 13 are formed on both main surfaces of the thick portion 11 so as to face each other. These excitation electrodes 12 and 13 have a rectangular shape in plan view, and are opposed to each other in the same shape and the same size on the front and back of the thick portion. Each side is arranged in parallel with each side of the thick portion 11 having a rectangular shape in plan view. The excitation electrodes may have different shapes on the front and back sides. For example, the electrode on the front surface may have a rectangular shape when viewed in plan, and the electrode on the back surface may have a diamond shape. In this case, it may contribute to suppression of unnecessary modes.

These excitation electrodes 12 and 13 are connected to extraction electrodes 12a and 13a (13a not shown), respectively. The extraction electrodes 12a and 13a have a width narrower than that of the excitation electrode, extend from the thick portion 11 to the thin portion 10 and are connected to the connection electrodes 12b and 13b, respectively.

The connection electrodes 12b and 13b have an area wider than the extraction electrode and are connected to the outside. The connection electrode 13b shown in FIGS. 1 and 2 is formed to wrap around from the connection electrode on the back surface through the side surface of the crystal diaphragm 1 to the front surface. (See Figure 3)

Further, the connection electrodes 12b and 13b are formed to be unevenly distributed at corners of other short sides different from one short side 1b of the crystal diaphragm 1, and both the connection electrodes 12b and 13b are provided close to each other. Yes.

With the above configuration, the connection electrodes 12b and 13b are unevenly distributed at the corner portion C1 of the quartz diaphragm 1, and the thick wall portion 11 and the excitation electrodes 12 and 13 are unevenly distributed at the corner portion C2 and are spaced apart in the diagonal direction. ing. The above-described excitation electrode, extraction electrode, and connection electrode have, for example, the same laminated structure of a plurality of metals. For example, the excitation electrode, the extraction electrode, and the connection electrode are each formed of a chromium layer formed of chromium (Cr) in the form of a film on the surface of the crystal diaphragm 1, and a gold layer made of gold (Au) or silver (Ag) on the upper surface. It is good also as a 2 layer structure which consists of a laminated structure which formed the silver layer formed in the shape. The laminated structure of these electrode films is not limited to the above example, and may be a three-layer structure of a chromium layer or a titanium layer, a gold layer, a silver layer, or a chromium layer, for example.

In this embodiment, the connection electrodes 12b and 13b are connected to the outside by forming metal bumps 12c and 13c (13c not shown) as conductive bonding materials. The metal bumps 12c and 13c are formed in a thick film shape using plating, and the planar view shape is circular or polygonal, and is formed on the upper surface of the connection electrodes 12b and 13b. The metal bump (conductive bonding material) may have a configuration in which a plurality of small metal bumps are provided on the connection electrode. With such a configuration in which a plurality of small metal bumps are provided, the applied pressure per unit area at the time of FC bonding can be reduced, and the reliability of bonding can be improved. The metal bump is made of gold (Au) or a gold alloy.

As shown in FIG. 3, the crystal diaphragm 1 is hermetically sealed in a package. The package includes a base 2 and a lid 3. The base 2 has a concave storage portion 21 as viewed in cross section and a bank portion 22 formed circumferentially outside the storage portion. In addition, an electrode pad 20 is formed on the bottom surface of the storage portion 21, and the electrode pad 20 is connected to an external connection terminal (not shown) outside the base (back surface). The external connection terminal is conductively bonded to a mounting electrode of a mounting board such as a printed wiring board.

  The metal bumps 12c and 13c of the crystal diaphragm 1 are FC-bonded to the electrode pad 20 of the base 2, and the upper surface of the lid 3 and the base portion of the base 2 is hermetically bonded at the bonding portion 21 in a vacuum atmosphere or an inert gas atmosphere. To obtain a crystal resonator.

  Next, a manufacturing method of a crystal resonator will be described below by taking processing using a photolithography technique as an example. The crystal diaphragm can be processed and formed with electrodes by using a photolithography technique.

  An AT-cut quartz wafer having an outer size capable of obtaining a large number of quartz diaphragms is prepared, and the surface of the quartz wafer is precisely polished to a predetermined thickness. Next, using a photolithography technique, a resist film for forming a thick part and a thin part is patterned for each crystal diaphragm. Thereafter, the quartz wafer is etched using the formed resist film to obtain a large number of rectangular quartz diaphragms having a thick part and a thin part. At this time, each crystal diaphragm is connected to the crystal wafer.

Next, a laminated film of electrodes is formed on the quartz wafer by using a vacuum deposition method or a sputtering method in the order of a chromium film and a gold film as electrode materials. Next, a resist film for electrode formation is patterned using a photolithography technique, and then a predetermined electrode pattern can be formed for each crystal diaphragm by performing etching according to the patterning.

Then, masking of the resist film having openings only in the connection electrode portions is performed using a photolithography technique, and metal bumps are formed by plating a gold film on the openings. The metal bumps are formed to have the same size as the connection electrode or smaller than the connection electrode. Also, a plurality of small metal bumps may be formed on the connection electrode to form a multipoint metal bump configuration.

Thereafter, each quartz crystal diaphragm is separated from the quartz wafer to obtain a rectangular quartz diaphragm having electrodes formed thereon. Note that the above-described electrode formation and metal bump formation procedures are examples, and for example, metal bumps may be formed first, and then multiple electrode patterns may be formed.

  Next, the base 2 is prepared, and the crystal diaphragm is held so that the metal bumps are bonded to the electrode pads, and FC bonding (flip chip bonding) is performed. After that, the base bank is joined with a lid and hermetically sealed. In addition, the airtight joining of a lid and a base can use joining using seam welding, joining using a metal brazing material, or joining using a glass brazing material.

  A second embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 4, the crystal resonator has a configuration in which a crystal diaphragm 4 is electromechanically bonded to the base 2. The basic configuration is the same as that of the first embodiment, except that the thick portion 41 is formed on both main surfaces, the taper 41a is formed at the boundary between the thick portion 41 and the thin portion 40, and the crystal The difference between the diaphragm 4 and the base 2 is that a conductive resin bonding material S is used.

  The quartz crystal plate 4 is formed of an AT-cut quartz plate, and is a rectangular quartz plate as a whole with a configuration having a long side in the crystal axis X-axis direction, a short side in the Z-axis direction, and a thickness in the Y-axis direction. . Further, the crystal diaphragm 4 has a thin portion 10 having a rectangular shape in plan view and a thick portion 11 having a rectangular shape in plan view, which is thicker than the thin portion 10. In this embodiment, the thick portion is formed inside the thin portion 40. It is a configuration. The thick portion has a long side and a short side, and is formed so as to be biased to one corner of the crystal diaphragm 4.

  In the present embodiment, the thick portion 41 has a thick configuration (bi-mesa configuration) in which the thickness is increased on both main surfaces (front and back surfaces) of the crystal diaphragm 4 as shown in FIG. In this case, the vibration energy confinement efficiency is improved, and a crystal resonator having good characteristics can be obtained.

  A taper 41 a is formed at the boundary between the thick portion 41 and the thin portion 40. The taper 41a has a configuration in which the thickness gradually changes, and may be formed over the entire circumference of the boundary, or may be formed in only a part so as to be formed only on two opposing sides, for example.

Excitation electrodes 42 and 43 are formed on both main surfaces of the thick portion 41 so as to face each other. These excitation electrodes 42 and 43 have a rectangular shape in plan view, and each side is arranged in parallel with each side of the thick portion 41 having a rectangular shape in plan view. The excitation electrodes may have different shapes on the front and back sides. For example, the electrode on the front surface may be rectangular and the electrode on the back surface may be diamond-shaped when viewed in plan. In this case, it may contribute to suppression of unnecessary modes.

These excitation electrodes 42 and 43 are connected to extraction electrodes 42a and 43a (43a not shown), respectively. The extraction electrodes 42a and 43a have a width narrower than that of the excitation electrode, extend from the thick portion 41 to the thin portion 40, and are connected to connection electrodes 42b and 43b (42b not shown), respectively.

The connection electrodes 42b and 43b have a wider area than the extraction electrode and are connected to the outside. The connection electrode 43b shown in FIGS. 1 and 2 is formed so as to wrap around from the connection electrode on the back surface to the surface via the side surface of the crystal diaphragm 4. (See Figure 3)

Further, the connection electrodes 42b and 43b are formed to be unevenly distributed at corners of other short sides different from one short side 4b of the crystal diaphragm 4, and both the connection electrodes 42b and 43b are provided close to each other. Yes.

With the above configuration, the connection electrodes 42b and 43b are unevenly distributed at the corners of the quartz crystal plate 4, and the thick wall portion 41 and the excitation electrodes 42 and 43 are unevenly distributed at the corners and are arranged in a diagonal direction. . The above-described excitation electrode, extraction electrode, and connection electrode have, for example, the same laminated structure of a plurality of metals. For example, the excitation electrode, the extraction electrode, and the connection electrode are each formed of a chromium layer formed of chromium (Cr) in the form of a film on the surface of the crystal diaphragm 1, and a gold layer made of gold (Au) or silver (Ag) on the upper surface. It is good also as a 2 layer structure which consists of a laminated structure which formed the silver layer formed in the shape. The laminated structure of these electrode films is not limited to the above example, and may be a three-layer structure of a chromium layer or a titanium layer, a gold layer, a silver layer, or a chromium layer, for example.

In the present embodiment, a conductive resin bonding material S (resin bonding material containing a conductive filler) is used as a conductive bonding material, and bonding to the outside is performed by conductive bonding of a base electrode pad. As an example of the conductive resin bonding material, a conductive resin bonding material using a silicone resin, a urethane resin, or an epoxy resin can be given.

As shown in FIG. 4, the crystal diaphragm 4 is hermetically sealed in the package. The package includes a base 2 and a lid 3. The base 2 has a concave storage portion 21 as viewed in cross section and a bank portion 22 formed circumferentially outside the storage portion. In addition, an electrode pad 20 is formed on the bottom surface of the storage portion 21, and the electrode pad 20 is connected to an external connection terminal (not shown) outside the base (back surface).

  The crystal diaphragm 4 is conductively bonded to the base electrode pad 20 with the conductive resin bonding material S, and the upper surface of the lid 3 and the bank portion of the base 2 is hermetically bonded at the bonding portion 21 in a vacuum atmosphere or an inert gas atmosphere. To obtain a crystal resonator.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a plan view showing the configuration of the crystal diaphragm.

  The crystal resonator has a structure in which a crystal diaphragm 5 is electrically and mechanically joined to a base by metal bumps 52c and 53c. Although the basic configuration is the same as that of the first embodiment, the configuration of the crystal diaphragm 5, the arrangement of the connection electrodes 52b and 53b, and the configuration of the metal bumps are different.

  The quartz diaphragm 5 is an AT-cut quartz diaphragm, and has a long side in the crystal axis X-axis direction, a short side in the Z-axis direction, and a thickness in the Y-axis direction. is there. The quartz diaphragm 5 has a thin portion 10 having a rectangular shape in plan view and a thick portion 11 having a rectangular shape in plan view which is thicker than the thin portion 10. In this embodiment, the thick portion is formed inside the thin portion 50. It is a configuration. The thick part 51 has a long side and a short side, and is formed so as to be biased to one corner C2 of the crystal diaphragm 5. Specifically, one long side 51 a of the thick part is adjacent to one long side 5 a of the crystal diaphragm 5 in a parallel state, and one short side 51 b of the thick part 51 is one of the crystal diaphragm 5. It is the structure which adjoined in the state parallel to the short side 5b. A chamfer 501 is formed on the square of the crystal diaphragm 50. This chamfer 501 may suppress a vibration mode related to, for example, contour vibration.

  In the present embodiment, the thick part 51 has a thick structure (planomesa structure) in which the thickness of only one main surface of the crystal diaphragm 5 is increased as shown in FIG. Since it only needs to be formed on one main surface, it is easy to manufacture, and there are advantages that the manufacturing error is small and the positioning of the energy confinement region is easy.

Moreover, the thick structure (bi-mesa structure) which thickness increased on both main surfaces (front and back) may be sufficient. In this case, the vibration energy confinement efficiency is improved, and a crystal resonator having good characteristics can be obtained.

Excitation electrodes 52 and 53 (53 is not shown) are formed on both main surfaces of the thick portion 51 so as to face each other. These excitation electrodes 52 and 53 have a rectangular shape in plan view, and each side is arranged in parallel to each side of the thick portion 51 having a rectangular shape in plan view.

These excitation electrodes 52 and 53 are connected to extraction electrodes 52a and 53a (53a not shown), respectively. The extraction electrodes 52a and 53a have a width smaller than that of the excitation electrode, extend from the thick portion 51 to the thin portion 50, and are connected to the connection electrodes 52b and 53b, respectively.

The connection electrodes 52b and 53b have a wider area than the extraction electrode and are connected to the outside. The connection electrode 53b shown in FIG. 1 and FIG. 2 is formed to wrap around from the connection electrode on the back surface to the surface via the side surface of the crystal diaphragm 5. (See Figure 3)

Further, the connection electrodes 52b and 53b are formed to be unevenly distributed at corners of other short sides different from the one short side 5b of the crystal diaphragm 5, and both the connection electrodes 52b and 53b are provided close to each other. Yes.

With the above configuration, the connection electrodes 52b and 53b are unevenly distributed at the corner portion C1 of the crystal diaphragm 1, and the thick portion 51 and the excitation electrodes 52 and 53 are unevenly distributed at the corner portion C2 and are arranged in a diagonally spaced direction. ing. The above-described excitation electrode, extraction electrode, and connection electrode have, for example, the same laminated structure of a plurality of metals. For example, an excitation electrode, an extraction electrode, and a connection electrode are each formed of a chromium layer formed of chromium (Cr) in the form of a film on the surface of the crystal diaphragm 5, and a gold layer made of gold (Au) or silver (Ag) on the upper surface thereof. It is good also as a 2 layer structure which consists of a laminated structure which formed the silver layer formed in the shape. The laminated structure of these electrode films is not limited to the above example, and may be a three-layer structure of a chromium layer or a titanium layer, a gold layer, a silver layer, or a chromium layer, for example.

In the present embodiment, metal bumps 52c and 53c (53c is not shown) are formed on the connection electrodes 52b and 53b as conductive bonding materials to be connected to the outside. The metal bumps 52c and 53c are formed in a thick film shape using plating, and the planar view shape is circular or polygonal, and is formed on the upper surfaces of the connection electrodes 52b and 53b.

As shown in FIG. 5, the metal bump 52c formed on the connection electrode 52b is smaller than the metal bump 53c formed on the connection electrode 53b. The excitation electrode formation region vibrates more strongly than the surrounding area when driving the quartz resonator, and even when the vibration energy is confined by the formation of the thick portion, vibration energy may propagate to the thin portion. is there. This vibration energy is gradually attenuated and propagates. However, by setting the outer size of the conductive bonding material close to the excitation electrode to be smaller than the outer size of the conductive bonding material far from the excitation electrode, a relatively undamped region is reduced. By joining with a conductive bonding material of a size, vibration can be attenuated smoothly without hindering main vibration. Further, the bonding strength can be improved by increasing the outer size of the conductive bonding material far from the excitation electrode.

The metal bump may have a configuration in which a plurality of small metal bumps are provided on the connection electrode. With such a configuration in which a plurality of small metal bumps are provided, the applied pressure per unit area at the time of FC bonding can be reduced, and the reliability of bonding can be improved. The metal bump is made of gold (Au) or a gold alloy.

The crystal diaphragm 5 is hermetically sealed in a package as shown in FIG. A crystal resonator plate is obtained by FC-bonding a crystal diaphragm to a base electrode pad and hermetically bonding the lid and the upper surface of the bank portion of the base in a vacuum atmosphere or an inert gas atmosphere.

  When the quartz diaphragm is stored in the storage portion of the base by the chamfer 501, the corner portion can be prevented from coming into contact with the storage portion, and the manufacturing yield can be improved.

  A fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a plan view showing the configuration of the crystal diaphragm.

  The crystal resonator has a structure in which a crystal diaphragm 6 is electrically and mechanically joined to a base by metal bumps 62c and 63c. Although the basic configuration is the same as that of the first embodiment, the shape of the crystal diaphragm and the configuration of the extraction electrode are different.

  The quartz crystal plate 6 is formed of an AT-cut quartz plate, and has a long side in the crystal axis X-axis direction, a short side in the Z-axis direction, and a thickness in the Y-axis direction. is there. The quartz diaphragm 6 has a thin-walled portion 10 that is rectangular in plan view and a thick-walled portion 11 that is thicker than the thin-walled portion 10 and is rectangular in plan view. In this embodiment, the thick-walled portion is formed inside the thin-walled portion 60. It is a configuration. The thick portion 61 has a long side and a short side, and is formed so as to be biased to one corner C2 of the crystal diaphragm 6. Specifically, one long side 61 a of the thick part is adjacent to one long side 6 a of the crystal diaphragm 6 in a parallel state, and one short side 61 b of the thick part is one short side of the crystal diaphragm 6. The configuration is close in parallel with the side 6b. The long side 6a and the long side 61a, and the short side 6b and the short side 61b may not be arranged in parallel. When parallelism is not located in this way, for example, a vibration mode related to contour system vibration may be suppressed.

  In the present embodiment, the thick part 61 has a thick structure (planomesa structure) in which the thickness of only one main surface of the crystal diaphragm 6 is increased as shown in FIG. Since it only needs to be formed on one main surface, it is easy to manufacture, and there are advantages that the manufacturing error is small and the positioning of the energy confinement region is easy.

Moreover, the thick structure (bi-mesa structure) which thickness increased on both main surfaces (front and back) may be sufficient. In this case, the vibration energy confinement efficiency is improved, and a crystal resonator having good characteristics can be obtained.

An overhang 60 a is formed at the other corner C <b> 1 of the crystal diaphragm 6. The projecting portion 60a has a rectangular configuration in plan view in which a part of the short side extends in the short side direction. The overhanging portion is not limited to the above configuration, and may be a configuration in which overhanging portions are formed on two sides adjacent to each other. The shape of the overhanging portion may be a polygon or a circle when seen in a plan view. May be.

Excitation electrodes 62 and 63 (63 is not shown) are formed on both main surfaces of the thick portion 61 so as to face each other. These excitation electrodes 62 and 63 have a rectangular shape in plan view, and each side is arranged parallel to each side of the thick portion 61 having a rectangular shape in plan view.

These excitation electrodes 62 and 63 are connected to extraction electrodes 62a and 63a (63a not shown), respectively. The extraction electrodes 62a and 63a have a narrower width than the excitation electrode, extend from the thick portion 61 to the thin portion 60, and are connected to the connection electrodes 62b and 63b, respectively. In FIG. 6, the extraction electrode extends from the short side of the thick part to the thin part and reaches the overhanging part of the long side.

The connection electrodes 62b and 63b have a wider area than the extraction electrode and are connected to the outside. The connection electrode 63b shown in FIGS. 1 and 2 is formed to wrap around from the connection electrode on the back surface through the side surface of the crystal diaphragm 6 to the front surface. (See FIG. 3) Further, the connection electrodes 62b and 63b are formed in parallel with the overhanging portion.

With the above configuration, the connection electrodes 62b and 63b are unevenly distributed at the corner C1 of the quartz diaphragm 6, and the thick portion 61 and the excitation electrodes 62 and 63 are unevenly distributed at the corner C2 and are spaced apart in the diagonal direction. It has become. The above-described excitation electrode, extraction electrode, and connection electrode each have, for example, the same laminated structure of a plurality of metals. For example, a chromium layer formed with a film of chromium (Cr) on the surface of a quartz diaphragm, and a gold layer formed with a film of gold (Au) or a silver layer formed with a film of silver (Ag) on the upper surface The laminated structure can be raised.

In the present embodiment, metal bumps 62c and 63c (63c is not shown) are formed on the connection electrodes 62b and 63b as conductive bonding materials, and are connected to the outside. The metal bumps 62c and 63c are formed on the thick film using plating, and the shape in plan view is circular or polygonal, and is formed on the upper surface of the connection electrode.

As shown in FIG. 6, the metal bump 62c formed on the connection electrode 62b is smaller than the metal bump 63c formed on the connection electrode 63b. The excitation electrode formation region vibrates more strongly than the surrounding area when driving the quartz resonator, and even when the vibration energy is confined by the formation of the thick portion, vibration energy may propagate to the thin portion. is there. This vibration energy is gradually attenuated and propagates. However, by setting the outer size of the conductive bonding material close to the excitation electrode to be smaller than the outer size of the conductive bonding material far from the excitation electrode, a relatively undamped region is reduced. By joining with the size conductive joining material, vibration can be attenuated smoothly. Further, the bonding strength can be improved by increasing the outer size of the conductive bonding material far from the excitation electrode.

The metal bump may have a configuration in which a plurality of small metal bumps are provided on the connection electrode. With such a configuration in which a plurality of small metal bumps are provided, the applied pressure per unit area at the time of FC bonding can be reduced, and the reliability of bonding can be improved. The metal bump is made of gold (Au) or a gold alloy.

As shown in FIG. 3, the crystal diaphragm 6 is hermetically sealed in the package. A crystal resonator plate is obtained by FC-bonding a crystal diaphragm to a base electrode pad and hermetically bonding the lid and the upper surface of the bank portion of the base in a vacuum atmosphere or an inert gas atmosphere. According to the present embodiment, the overhanging portion 60a makes it difficult for vibration from the thick-walled portion to propagate, and even when the crystal diaphragm is supported by the connection electrode, the characteristics are not deteriorated and good. A crystal resonator with special characteristics can be obtained.

  A fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a plan view showing the configuration of the crystal diaphragm.

  The crystal resonator has a structure in which a crystal diaphragm 7 is electromechanically bonded to a base by metal bumps 72c and 73c. Although the basic configuration is the same as that of the first embodiment, the configuration of the thick portion 71 and the configuration of the excitation electrode are different.

  The quartz crystal diaphragm 7 is composed of an AT-cut quartz crystal diaphragm, and has a configuration having a long side in the crystal axis X-axis direction, a short side in the Z-axis direction, and a thickness in the Y-axis direction. is there. The quartz diaphragm 7 has a thin portion 10 having a rectangular shape in plan view and a thick portion 11 having a rectangular shape in plan view which is thicker than the thin portion 10. In this embodiment, the thick portion is formed inside the thin portion 70. It is a configuration. In the present embodiment, the thick portion 71 has a long side and a short side, and is formed in the center portion in the width direction of the crystal diaphragm 7.

  In the present embodiment, the thick part 71 has a thick structure (planomesa structure) in which the thickness of only one main surface of the crystal diaphragm 7 is increased as shown in FIG. Since it only needs to be formed on one main surface, it is easy to manufacture, and there are advantages that the manufacturing error is small and the positioning of the energy confinement region is easy.

Moreover, the thick structure (bi-mesa structure) which thickness increased on both main surfaces (front and back) may be sufficient. In this case, the vibration energy confinement efficiency is improved, and a crystal resonator having good characteristics can be obtained.

Excitation electrodes 72 and 73 (73 is not shown) are formed on both main surfaces of the thick portion 71 so as to face each other. These excitation electrodes 72 and 73 have a rectangular shape in plan view, and each side is arranged in parallel to each side of the thick portion 71 having a rectangular shape in plan view. In the present embodiment, the excitation electrodes 72 and 73 are formed so as to be biased toward one corner C21 of the thick portion 71. With this configuration, the excitation electrodes 72 and 73 are arranged so as to be biased to the corner portion C2 of the crystal diaphragm.

These excitation electrodes 72 and 73 are connected to extraction electrodes 72a and 73a (73a not shown), respectively. The extraction electrodes 72a and 73a have a width narrower than that of the excitation electrode, extend from the thick portion 71 to the thin portion 70, and are connected to the connection electrodes 72b and 73b, respectively.

The connection electrodes 72b and 73b have a wider area than the extraction electrodes and are connected to the outside. The connection electrode 73b shown in FIGS. 1 and 2 is formed to wrap around from the connection electrode on the back surface through the side surface of the crystal diaphragm 7 to the front surface. (See Figure 3)

Further, the connection electrodes 72b and 73b are formed so as to be unevenly distributed at corners of other short sides different from the one short side 7b of the crystal diaphragm 7, and both the connection electrodes 72b and 73b are provided close to each other. Yes.

With the above configuration, the connection electrodes 72b and 73b are unevenly distributed at the corner portion C1 of the quartz diaphragm 7, and the thick portion 71 and the excitation electrodes 72 and 73 are unevenly distributed at the corner portion C2 and are spaced apart in the diagonal direction. ing. The above-described excitation electrode, extraction electrode, and connection electrode each have, for example, the same laminated structure of a plurality of metals. For example, a chromium layer formed with a film of chromium (Cr) on the surface of a quartz diaphragm, and a gold layer formed with a film of gold (Au) or a silver layer formed with a film of silver (Ag) on the upper surface The laminated structure can be raised.

In the present embodiment, metal bumps 72c and 73c (73c is not shown) are formed on the connection electrodes 72b and 73b as conductive bonding materials for connection to the outside. The metal bumps 72c and 73c are formed on a thick film using plating, and the shape in plan view is circular or polygonal, and is formed on the upper surface of the connection electrode.

As shown in FIG. 3, the crystal diaphragm 7 is hermetically sealed in the package. The package includes a base 2 and a lid 3. The base has a concave storage portion 21 as viewed in cross section and a bank portion 22 formed circumferentially outside the storage portion. An electrode pad 20 is formed on the bottom surface of the storage portion, and the electrode pad is connected to an external connection terminal (not shown) outside the base (back surface).

  A crystal resonator plate is obtained by FC-bonding a crystal diaphragm to a base electrode pad and hermetically bonding the lid and the upper surface of the bank portion of the base in a vacuum atmosphere or an inert gas atmosphere.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit, gist, or main features. For this reason, 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.

  Applicable for mass production of crystal units.

1, 4, 5, 6, 7 Quartz diaphragm 11, 41, 51, 61, 71 Thick part 10, 40, 50, 60, 70 Thin part 12, 13, 42, 43, 52, 53, 62, 63 72, 73 Excitation electrodes 12b, 13b, 42b, 43b, 52b, 53b, 62b, 63b, 72b, 73b Connection electrodes

Claims (6)

A rectangular crystal diaphragm including a thick part, a thin part, and a connection electrode connected to the outside by a conductive bonding material,
The excitation electrode is formed in the thick part, and the excitation electrode is connected to the connection electrode,
The quartz vibrator according to claim 1, wherein the excitation electrode and the connection electrode are spaced apart from each other in a diagonal direction of the quartz diaphragm. A quartz diaphragm having a thick part, a thin part, and a connection electrode connected to the outside by a conductive bonding material,
The excitation electrode is formed in the thick part, and the excitation electrode is connected to the connection electrode,
The quartz resonator according to claim 1, wherein the thick part and the connection electrode are spaced apart from each other in a diagonal direction of the quartz diaphragm. 3. The crystal resonator according to claim 1, wherein the conductive bonding material is made of a metal bump, and the connection electrode is electrically and mechanically connected to the outside by the metal bump. 4. The crystal resonator according to claim 1, wherein a boundary between the thick portion and the thin portion is tapered. 5. 5. The crystal vibration according to claim 1, wherein a protruding portion is formed on one side of the quartz diaphragm or two sides adjacent to each other, and the connection electrode is formed on the protruding portion. Child. The connection electrode is composed of a pair, and each connection electrode is bonded to the outside by the conductive bonding material, and the outer size of the conductive bonding material close to the excitation electrode is far from the excitation electrode. The crystal unit according to claim 1, wherein the crystal unit is smaller.

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