JP2013232778A - Tuning fork type piezoelectric vibration piece and tuning fork type piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tuning fork type piezoelectric vibration piece which has resistance to stress and external force and is suitable for the downsizing, and to provide a tuning fork type piezoelectric vibrator.SOLUTION: A tuning fork type piezoelectric vibration piece 2 is composed of a pair of leg parts 21, 22 and a base part 25. The leg parts protrude from one end surface of the base part to be arranged in parallel with the one end surface, and a crotch portion 253 is formed between the pair of legs. A pair of through holes 241, 242 is formed along the one end surface of the base part and the base part includes joint regions 235, 236 at the other end surface 252 side of the base part. The pair of through holes is formed at positions which are located closer to a center line P in a width direction of the base part than base end parts 212, 222 of the pair of the leg parts so that their through holes do not contact with each other. In each through hole, a plane area of the through hole gradually becomes smaller from both end parts of the through hole on front and rear main surfaces of the tuning fork type piezoelectric vibration piece toward the inner part of the tuning fork type piezoelectric vibration piece, and a wall surface of the through hole is formed into a spiral shape. A planar view shape of the through hole is formed into a substantially regular polygon shape composed of five or more arc shaped ridges.

Description

  The present invention relates to a tuning-fork type piezoelectric vibrating piece used for electronic equipment and the like, and a tuning-fork type crystal resonator using the same.

  Piezoelectric vibration devices represented by piezoelectric vibrators are widely used in mobile communication devices such as mobile phones. There is a tuning fork type piezoelectric vibrating piece as one of the piezoelectric vibrating pieces used in the piezoelectric vibrator. The tuning fork-type piezoelectric vibrating piece is a tuning-fork-shaped piezoelectric vibrating piece including a base and a pair of vibrating legs (hereinafter referred to as legs) extending in one direction from the base, and is a tuning fork type using the tuning-fork type piezoelectric vibrating piece. Piezoelectric vibrators are widely used as clock sources for watches.

  For example, in the tuning fork type piezoelectric vibrating piece described in Patent Document 1, a joint portion to be joined to the outside is further formed so as to protrude from the other end surface facing one end surface on which two leg portions of the base portion are formed. The joints formed so as to protrude from the other end surfaces of the base portions are formed by extending into two T-shapes along both side surfaces from the other end surfaces of the base portions, and the tip portions are the tip ends of the two leg portions. Facing in the same direction.

  In this tuning fork type piezoelectric vibrator, the main body case is composed of a base and a lid. Inside the main body case, the tip of the joint of the tuning fork type piezoelectric vibrating piece is made of an electrically conductive material on the base. The joined tuning fork type piezoelectric vibrating piece is hermetically sealed inside the main body housing. According to this tuning fork type piezoelectric vibrator, vibration leakage (acoustic leakage) can be prevented.

JP 2004-357178 A

  As described above, according to the tuning fork type piezoelectric vibrator described in Patent Document 1, the tip of the joint portion of the tuning fork type crystal vibrating piece is electromechanically joined to the base by a conductive material. The lead electrode from the leg portion, which is a portion, to the joining position of the base becomes long, and vibration generated in the leg portion is difficult to be transmitted. However, on the other hand, the joining position to the base is the tip of the joining part, the vibration part is the leg part, and the substantial length through the base part becomes long, so that the vibration stress and the tuning fork type piezoelectric vibrator It is difficult to withstand the external force when an impact is applied from the outside, and the piezoelectric vibrating piece is easily cracked by receiving stress or external force at the base or the joint. In addition, since the total length of the joint in plan view is long, it is necessary to secure a base mounting area for mounting the joint having a long plan view overall length. Hinder.

  The present invention has been made in view of such points, and an object of the present invention is to provide a tuning fork type piezoelectric vibrating piece and a tuning fork type piezoelectric vibrator that are suitable for miniaturization that is resistant to stress and external force while preventing acoustic leakage. To do.

In order to achieve the above object, in the tuning-fork type piezoelectric vibrating piece, the piezoelectric vibrating element plate is composed of a pair of leg portions that are made of quartz and are vibrating portions, and a base portion that protrudes from the leg portions. The leg portions are juxtaposed so as to protrude from one end surface of the base portion, and between the pair of leg portions, a fork portion is formed at an intermediate position in the width direction of the one end surface of the base portion. A pair of through holes are formed along one end surface of the base portion, and a bonding region is formed on the other end surface side facing the one end surface of the base portion, and the pair of through holes are connected to the pair of legs. Formed at a position closer to the center line in the width direction of the base part than the base end part of the part in a state where the mutual (reciprocal) through holes do not contact each other,
In the through hole, the plane area of the through hole gradually decreases from both end portions of the through hole on the front and back main surfaces of the piezoelectric vibration element plate toward the inside of the piezoelectric vibration element plate, and The wall surface is formed in a spiral shape, and the planar view shape of the through-hole is formed in a substantially regular polygonal shape constituted by five or more arc-shaped ridge sides.

  According to the present invention, acoustic leakage can be prevented more efficiently without hindering downsizing of the tuning fork type piezoelectric vibrating piece, which is resistant to stress and external force, and causes problems such as cracking of the tuning fork type piezoelectric vibrating piece. Can be prevented.

  That is, the fork is formed at an intermediate position in the width direction of the one end surface of the base, and the pair of through holes are formed in the base along the one end surface of the base. The joining region is provided on the opposite other end surface side, and the pair of through holes are located closer to the center line in the width direction of the base portion than the base end portions of the pair of leg portions, and mutually (mutually) Since it is formed in a state where the through hole is not in contact, it is possible to suppress vibration leakage (acoustic leakage) caused by vibration imbalance generated when exciting the tuning fork type piezoelectric vibrating piece. In the joint region, the propagation of a part of vibration energy generated by the pair of leg portions can be cut off by the through hole formed in the base portion.

  In particular, the through hole is formed such that the flat area of the through hole gradually decreases from both end portions of the through hole on the front and back main surfaces of the piezoelectric vibrating element plate to the inside of the piezoelectric vibrating element plate like an hourglass. Moreover, since the wall surface of the through hole is also formed in a spiral shape, the external stress can be dispersed while gradually weakening along the spiral wall surface of the through hole, and is generated in the pair of legs. A part of vibration energy can be propagated while gradually weakening along the spiral wall surface of the through hole.

  In addition, since the shape of the through hole in plan view is formed in a substantially regular polygonal shape constituted by five or more arcuate ridges, the connection point between the ridge and the ridge that is the opening end of the through hole Uniformity can be given to each corner, and since one corner becomes an obtuse angle of 90 ° or more, stress concentration at each corner is less likely to occur, and cracks occur at each corner. Suppress. Furthermore, since it is a substantially regular polygonal shape formed by arc-shaped ridges, the stress transmitted to each ridge is also uniformly distributed. As a result, not only the strength at the opening end of the through-hole is improved, but the configuration of the opening end of these through-holes is combined with the configuration formed in a spiral shape along the wall surface to synergistically concentrate stress. It is even more preferable to eliminate the propagation of vibration energy because the generation of further cracks can be suppressed.

  As described above, vibration leakage (acoustic leakage) can be more efficiently suppressed, and the structure that is strong against stress and external force can be used as the joint region with the outside. For example, the tuning fork type piezoelectric vibrating piece is mounted on the outside, such as mounting the tuning fork type piezoelectric vibrating piece, or an external force is applied to the tuning fork type piezoelectric vibrating piece. However, according to the present invention, such a problem can be greatly reduced. In addition, since it is possible to suppress physical and electrical breakage in the joining region, durability such as impact resistance is improved.

  The through hole has a substantially regular polygonal shape with an even number of ridge sides, and two opposing ridge sides of the substantially regular polygon are arranged in a direction perpendicular to the protruding direction of the leg portion. May be.

  In this case, in addition to the above-described effects, even if a bending variation occurs with respect to the leg portion of the tuning-fork type piezoelectric vibrating piece due to a drop impact or the like, the stress of this bending variation is the leg portion of the two opposing ridge sides. By being supported by the ridge side closer to, stress concentration is less likely to occur, and the generation of cracks at this portion is further suppressed.

  In order to achieve the above object, the tuning fork type piezoelectric vibrator according to the present invention includes the tuning fork type piezoelectric vibrating piece according to the present invention provided inside the casing of the tuning fork type piezoelectric vibrator and hermetically sealed. It is characterized by. The present invention can also be applied to a tuning fork type piezoelectric vibrator configured as described above, for example, in which the first joining region of the tuning fork type piezoelectric vibrating piece is joined to the holding portion inside the housing. The same effect can be obtained as a tuning fork type piezoelectric vibrator in which a piezoelectric vibrating piece is joined to a holding portion inside a housing and hermetically sealed.

  As described above, according to the present invention, it is possible to provide a tuning fork-type piezoelectric vibrating piece and a tuning-fork type piezoelectric vibrator that are suitable for miniaturization that is resistant to stress and external force while preventing acoustic leakage.

FIG. 1 is a schematic cross-sectional view showing the configuration of a tuning fork type crystal resonator showing an embodiment of the present invention. FIG. 2 is a plan view of one main surface side of the tuning-fork type crystal vibrating piece showing the embodiment of the present invention. FIG. 3 is a plan view of the other main surface side of the tuning-fork type crystal vibrating piece showing the embodiment of the present invention. FIG. 4 consists of FIG. 4A and FIG. 4B, and FIG. 4A is a schematic plan view of a through hole formed in a tuning fork type crystal vibrating piece showing an embodiment of the present invention. FIG. 4B is a schematic cross-sectional view thereof.

  Hereinafter, a tuning fork type crystal resonator will be described as an example with reference to the drawings. The tuning fork type crystal resonator 1 used in the present embodiment includes a base 3 and a lid (not shown) joined via a sealing member H to form a casing. Specifically, the tuning fork type crystal vibrating piece 2 is bonded to the electrode pad 32 of the base 3 having an opening at the top via a metal film M1 such as a plating bump, and the lid is bonded to the base 3 via the sealing member H. The storage part is hermetically sealed (see below). Here, in this embodiment, the nominal frequency of the tuning fork type crystal resonator 1 is 32.768 kHz. In addition, this nominal frequency is an example and can be applied to other frequencies.

  The base 3 is composed of an insulating container made of, for example, a ceramic material, a glass material, or a resin material. The base 3 has a bank portion 30 around it, and is formed in a concave shape in cross section with an upper opening, and a step portion for mounting the tuning fork type crystal vibrating piece 2 inside the base 3 (storage portion). 31 is formed. A pair of electrode pads 32 (only one of which is shown in FIG. 1) on which the tuning fork type crystal vibrating piece 2 is mounted is formed on the upper surface of the step portion 31. The pair of electrode pads 32 are electrically connected to two or more terminal electrodes 33 formed on the bottom surface (back surface) of the base 3 through a wiring pattern (not shown) formed inside the base 3. On the top surface (periphery) of the bank portion 30 of the base 3, a metal film layer 34 (constituting a part of the sealing member H) is formed in a circumferential shape along the top surface. For example, when a ceramic material is used for the base 3, the electrode pad 32, the terminal electrode 33, and the metal film layer 34 are composed of, for example, a three-layered structure, and in the order of tungsten, nickel, and gold from the bottom. Are stacked. Tungsten is integrally formed during ceramic firing by metallization technology, and the nickel and gold layers are formed by plating technology. Note that molybdenum may be used for the tungsten layer.

  The lid (not shown) is made of, for example, a metal material, a ceramic material, or a glass material, and is formed into a single plate having a rectangular shape in plan view. A sealing material (constituting a part of the sealing member H) is formed on the lower surface of the lid. This lid is joined to the base 3 via the sealing material H by a technique such as seam welding, beam welding, heat fusion joining, etc., and the casing of the tuning fork type crystal resonator 1 is constituted by the lid and the base 3.

  The tuning-fork type crystal vibrating piece 2 is a piezoelectric vibrating element plate, and a large number of tuning-fork type crystal vibrating pieces 2 are collectively formed from one crystal wafer (not shown) made of a crystal Z plate made of anisotropic material. With respect to the outer shape forming of the tuning fork type crystal vibrating piece 2, a resist or a metal film is formed on a quartz wafer using a photolithography technique, and the tuning fork type quartz crystal is formed by wet etching, for example, using the resist or the metal film formed on the quartz wafer as a mask. The resonator element 2 is formed with an outer shape.

  As shown in FIGS. 2 and 3, the tuning fork type crystal vibrating piece 2 includes a pair of first leg portions 21 and second leg portions 22 which are vibrating portions, and an external portion (in this embodiment, an electrode pad 32 of the base 3). The first leg portion 21, the second leg portion 22, and a base portion 25 provided by projecting the joint portion 23. A fork 253 is formed between the pair of first leg 21 and second leg 22 and at an intermediate position in the width direction of the one end face 251 of the base 25. On the front and back main surfaces (one main surface 261 and the other main surface 262) of the tuning-fork type crystal vibrating piece 2, at least a pair of excitation electrodes 291 and 292 and extraction electrodes 293 extracted from the pair of excitation electrodes 291 and 292, respectively. , 294. Further, on one main surface 261 of the tuning-fork type crystal vibrating piece 2, connection electrodes 295 and 296 are formed which are lead-out end portions of the lead electrodes 293 and 294 and are formed at the joint portion 23 joined to the outside. . Further, part of the extraction electrodes 293 and 294 (the other end portions 297 and 298) are extracted to the fork portion 253 (including the vicinity of the fork portion 253). In particular, in the present embodiment, the through holes 241 and 242 are formed, and the lead electrodes 293 and 294 are routed using the through holes 241 and 242. Therefore, it is not necessary to route the extraction electrodes 293 and 294 at the fork portion 253, and the other end portions 297 and 298 of the extraction electrodes 293 and 294 are located at the fork portion 253 (including the vicinity of the fork portion 253). Can do. Therefore, in this embodiment, it is not necessary to design the routing pattern of the extraction electrodes 293 and 294 between the fork portion 253 and the through holes 241 and 242, and the other end portions 297 and 298 of the extraction electrodes 293 and 294 It is not pulled out between the base end portion 212 of the first leg portion 21 and the base end portion 222 of the second leg portion 22 in contact with the portion 253 (including the vicinity of the fork portion 253). Therefore, even if the other end portions 297 and 298 of the extraction electrodes 293 and 294 are in contact with the fork portion 253 (including the vicinity of the fork portion 253), and the formation displacement of the extraction electrodes 293 and 294 occurs, disconnection does not occur. In addition, since the routing pattern of the extraction electrodes 293 and 294 is not designed on the fork portion 253 (including the vicinity of the fork portion 253), the excitation electrodes 291 and 292 can be made wider and larger. As a result, the series resonance resistance value (CI value) can be reduced. In addition, since it is not necessary to secure the design area of the lead pattern of the extraction electrodes 293 and 294 in the vicinity of the fork portion 253 (including the vicinity of the fork portion 253) of the tuning fork type crystal vibrating piece 2, the extraction electrodes 293 and 294 For the purpose of conduction, it is necessary to make the base plate shape of the fork portion 253, the base end portion 212 of the first leg portion 21 and the base end portion 222 of the second leg portion 22 into a tapered shape or an arc shape with a large R. Therefore, it is easy to cope with downsizing of the tuning-fork type crystal vibrating piece 2. For this reason, disconnection or the like is unlikely to occur in the lead electrodes 293 and 294 formed on the front and back main surfaces (one main surface 261 and the other main surface 262) of the base portion 25 of the tuning fork type piezoelectric vibrating piece 2, and the wiring is simplified. Pattern design is facilitated, and downsizing of the base 25 of the tuning fork type piezoelectric vibrating piece 2 can be realized at the same time.

The base 25 has a symmetrical shape in plan view, and as shown in FIGS. 2 and 3, as shown in FIG. 2 and FIG. (Refer to the above) Further, a step is gradually formed in the vicinity of the other end surface 252 of the base portion 25 so as to become narrower from the one end surface 251 to the other end surface 252. For this reason, the leakage vibration generated by the vibrations of the first leg portion 21 and the second leg portion 22 that are the vibration portions can be attenuated by the other end surface 252, and the transmission of the leakage vibration to the joint portion 23 can be suppressed. This is preferable for further reducing acoustic leakage (vibration leakage). In addition, as a structure where the width | variety becomes gradually narrow here, the width | variety of the base 25 is narrow with respect to the one end surface 251 vicinity with the large width dimension of the base 25 on the basis of the planar view whole shape of the base 25. (Hereinafter, this portion is referred to as a constricted portion 255). In addition, the portion where the width of the base 25 is the narrowest in the constricted portion 255 is one end, and one end of the constricted portion 255 is the end of the base 25. This is a boundary (boundary point) between the other end face 252 and the joint 23, and is P3 shown in FIG. Further, the constricted portion 255 is not limited to the step shape shown in FIGS. 2 and 3, and may be a tapered shape or a curved surface shape, or may be a combination of these shapes.
Further, a pair of through holes 241 and 242 are formed side by side along (in parallel with) the one end surface 251 on the one end surface 251 of the base portion 25. The pair of through holes 241 and 242 are positioned closer to the center line P (see FIG. 2) in the width direction of the base portion 25 than base end portions 212 and 222 of a pair of leg portions 21 and 22, which will be described later. It is formed symmetrically with respect to the center line P in the width direction of the base 25 in a state where the mutual (through) 241 and 242 are not in contact with each other.

  Further, regarding the pair of through holes 241, 242, a line segment connecting a first joining region 235 described later and the center of the base end portion 212 of the leg portion 21 is defined as Q1, and the first joining region 235 and the leg portion 22 are connected to each other. A pair of through holes 241 and 242 are formed at positions on the line segments Q1 and Q2, where Q2 is a line segment connecting the center of the base end 222. For this reason, the propagation of vibration energy can be cut off more efficiently, and vibration leakage (acoustic leakage) can be suppressed even more efficiently.

  The through holes 241 and 242 are formed in the region where the extraction electrodes 293 and 294 are formed, and a conduction electrode (not shown) is formed inside the through holes 241 and 242. The conducting electrodes formed in the through holes 241 and 242 may be formed only on the wall surface S1 of the through holes 241 and 242 or may be formed in a state in which the through holes 241 and 242 are filled with the conducting electrodes. . With such a configuration of the through holes 241 and 242, the lead electrodes 293 and 294 formed on the one main surface 261 are led to the same lead electrode 293 and 294 on the other main surface 262, respectively.

  Further, as shown in the plan view of FIG. 4A, the inner wall surface of the through holes 241 and 242 is composed of a plurality of wall surfaces S1, and the wall surfaces inside the through holes 241 and 242 are formed by the plurality of wall surfaces S1. It is formed in a spiral shape. Further, in the through holes 241, 242, as shown in the cross-sectional view of FIG. 4 (b), the front and back main surfaces (one main surface 261 and the other main surface 262) of the tuning fork type crystal vibrating piece 2 are penetrated like an hourglass. Gradually from the both ends T1 and T2 of the holes 241 and 242 toward the inside T3 of the tuning-fork type crystal vibrating piece 2, the flat area of the through holes 241 and 242 (related to the opening diameter and opening width of the through holes 241 and 242) Opening area to be reduced).

  Further, the plan view shape of both end portions T1, T2 (open end portions) of the through holes 241 and 242 is constituted by five or more arc-shaped ridge sides, as shown in the plan view of FIG. And it forms in the substantially regular polygon shape which is an even-numbered edge. Specifically, it consists of a substantially regular hexagon formed by six arc-shaped ridge sides, and two ridge sides 2411 and 2412 and two ridge sides 2421 and 2422 facing each other among the six ridge sides are first. The leg portion 21 and the second leg portion 22 are formed in a direction orthogonal to the protruding direction. Such a configuration of the through holes 241 and 242 is such that the temperature and concentration of the etching solution are not over-etched when the through holes 241 and 242 are formed by wet etching on an anisotropic crystal material such as quartz. Is optimally set, and the etching time is optimally managed. In this embodiment, the shape in plan view is a substantially regular hexagon. However, the shape is not limited to this and may be a substantially regular pentagon or more, and may be a substantially regular octagon, a substantially regular hexagon, or the like.

  Further, by forming the through holes 241 and 242 as shown in FIG. 4, the stress from the outside is dispersed while gradually weakening along a plurality of wall surfaces S <b> 1 arranged (formed) in a spiral shape. The propagation of part of the vibration energy generated by the vibration of the first leg portion 21 and the second leg portion 22 that are the vibration portions is also released while gradually weakening along the spiral wall surfaces S1 of the through holes 241 and 242. be able to.

  In addition, since the flat areas of the through holes 241 and 242 can be gradually reduced from both end portions T1 and T2 of the through holes 241 and 242 toward the inside T3 of the through holes 241 and 242, the surface areas of the through holes 241 and 242 are reduced. Can be increased, and the conduction state of the conduction electrode can be stabilized.

  As shown in FIGS. 2 and 3, the pair of first leg portion 21 and second leg portion 22 protrude from one end surface 251 of the base portion 25 and are arranged in parallel via the fork portion 253. Note that the fork portion 253 here is provided at an intermediate position (central region) in the width direction of the one end surface 251 and refers to a region between two boundary points P1 (see FIG. 5). The distal end portions 211 and 221 and the proximal end portions 212 and 222 of the first leg portion 21 and the second leg portion 22 are in a protruding direction as compared with other portions of the first leg portion 21 and the second leg portion 22. Widely shaped in the orthogonal direction. Among these, the wide regions of the tip portions 211 and 221 of the first leg portion 21 and the second leg portion 22 are referred to as wide regions of the first leg portion 21 and the second leg portion 22. In addition, the corners of the tip portions 211 and 221 of the first leg portion 21 and the second leg portion 22 are curved. By forming the tip portions 211 and 221 wide in this way, the tip portions 211 and 221 (tip regions) can be used effectively, which is useful for downsizing the tuning-fork type crystal vibrating piece 2 and has a low frequency. It is also useful for conversion. In addition, by forming the corners of the tip portions 211 and 221 as curved surfaces, it is possible to prevent contact with a bank portion or the like when receiving an external force. Here, the corners of the tip portions 211 and 221 are not limited to curved surfaces, and may be tapered, or may be a shape combining curved surfaces and tapered corners.

  In addition, the one main surface 261 and the other main surface 262 of the pair of first leg portion 21 and second leg portion 22 have a series resonance resistance value (CI in the present embodiment) that deteriorates due to the downsizing of the tuning-fork type crystal vibrating piece 2. In order to improve the value (hereinafter the same), the groove portions 27 are respectively formed. Further, a part of the side surface 28 of the outer shape of the tuning fork type crystal vibrating piece 2 is formed to be inclined with respect to the one main surface 261 and the other main surface 262. This is because the etching speed in the crystal direction (X, Y direction) of the substrate material is different when the tuning fork type crystal vibrating piece 2 is formed by wet etching.

  As shown in FIGS. 2 and 3, the joining portion 23 has an extraction electrode 293 and 294 described below as an external electrode (external in the present invention, in this embodiment, the electrode pads 32 and 32 of the base 3) and electromechanical. It is for joining. Specifically, the joint portion 23 is formed to project from an intermediate position (central region) in the width direction of the other end surface 252 facing the one end surface 251 of the base 25 from which the pair of first leg portions 21 and second leg portions 22 project. Has been. That is, the joint portion 23 is formed so as to protrude at a position facing the fork portion 253 disposed between the pair of first leg portions 21 and second leg portions 22.

  In particular, in the present embodiment, the joining portion 23 includes a short side portion 231 narrower than the other end surface 252 that protrudes in the vertical direction with respect to the other end surface 252 of the base portion 25, and a distal end portion of the short side portion 231. A long side portion 232 that is bent at a right angle in plan view at the distal end portion of the continuous short side portion 231 and extends in the width direction of the base portion 25, and the distal end portion 233 of the joint portion 23 faces the width direction of the base portion 25. ing. That is, the joining portion 23 is formed in an L shape in plan view, and a bent portion 234 that is a bent portion formed in an L shape in plan view corresponds to the tip portion of the short side portion 231. Thus, since the short side part 231 is formed in a narrower state than the other end face 252 of the base part 25, the effect of further suppressing vibration leakage is enhanced.

  In addition, the main surface 261 of the joint portion 23 includes a first joint region 235 and a second joint region 236 that are joined to the outside, and the first joint region 235 extends in the width direction of the base portion 25. It is formed in one region of the bent portion 234 of the joint portion 23 formed in an L shape in plan view on the center line P on the extension line (intermediate position in the width direction of the short side portion 231 of the joint portion 23), The joining region 236 is formed in one region of the distal end portion of the long side portion 232 corresponding to the distal end portion 233 of the joining portion 23 formed in an L shape in plan view. In the first bonding region 235, a connection electrode 296 (leading end portion of the extraction electrode 294) drawn from an end portion (to one end portion) of the short side portion 231 through the extraction electrode 294 from a second excitation electrode 292 described later. ) And the connection electrode 295 (extraction electrode) extracted from the first excitation electrode 291 (described later) through the extraction electrode 293 to the end portion (tip end portion 233) of the long side portion 232 is formed in the second bonding region 236. 293 lead-out end).

  With this configuration, vibration leakage (acoustic leakage) can be more efficiently suppressed without increasing the length of the joint portion 23. In particular, the first joint region 235 joined to the outside in the joint portion 23 can be electrically and mechanically joined as one pole at the bent portion 234 in which acoustic leakage is more efficiently suppressed. The second joining region 236 joined to the outside at 23 can be electromechanically joined as the other pole at the tip 233 that is not affected by acoustic leaks, stress or external force.

Further, on the upper surfaces of these connection electrodes 295 and 296, metal films M1 (M11 and M12) are formed as plating bumps having a rougher surface roughness and a smaller flat area than the connection electrodes 295 and 296. The metal film M1 (M11, M12) is formed in a circular shape in plan view with a thickness of, for example, about 5 to 20 μm, a diameter of about 50 μm, and a plane area of about 1962.5 μm ² . After ultrasonic bonding (after FCB), at least the metal film M1 (M11, M12) expands in the surface direction and is crushed, and has a thickness of about half. When the thickness of the metal film M1 (M11, M12) is smaller than 5 μm, the gap between the connection electrodes 295, 296 of the tuning-fork type crystal vibrating piece 2 and the electrode pads 32, 32 of the base 3 becomes small, and the tuning-fork type crystal resonator 1 It tends to adversely affect the electrical characteristics of the. When the thickness of the metal film M1 (M11, M12) is larger than 20 μm, the tuning fork type crystal vibrating piece 2 is likely to be influenced by the inclination and displacement, and the bonding strength is likely to vary. The planar shape of the metal film M1 (M11, M12) as the plating bump is a circular shape such as a circle or an ellipse, or a polygonal shape including a rectangle or a square, depending on the planar view shape of the connection electrode or the like. Things can be configured freely.

  Regarding the formation of the metal film M1 (M11, M12) at the joint 23, the metal film formation part (connection electrodes 295, 296) (not shown) is formed in the first joint region 235 and the second joint region 236 of the joint 23. A mask having a window portion with a small plane area) is formed into a desired shape (rectangular window portion in this embodiment) by photolithography, and the metal film M1 (M11, M12) is formed on the formation portion of the metal film M1 (M11, M12). M11, M12) are plated by a technique such as electrolytic plating. Thereafter, an annealing treatment may be performed.

  In addition, the tuning fork type crystal vibrating piece 2 according to the present embodiment includes a pair of first excitation electrode 291 and second excitation electrode 292 configured with different potentials, and the first excitation electrode 291 and the second excitation electrode 292. Lead electrodes 293 and 294 drawn from the first and second excitation electrodes 291 and 292 to be electrically connected to the electrode pads 32 and 32, and a connection electrode 295 having a metal film M1 formed at the tip thereof , 296 are integrally formed simultaneously. Note that the extraction electrodes 293 and 294 in the present embodiment refer to electrode patterns extracted from the pair of first excitation electrode 291 and second excitation electrode 292. The connection electrodes 295 and 296 indicate those formed at locations where the leading portions (leading end portions) of the extraction electrodes 293 and 294 are joined to the base 3.

  A part of the pair of first excitation electrode 291 and second excitation electrode 292 is formed inside the groove portion 27. For this reason, even if the tuning fork type crystal vibrating piece 2 is downsized, the vibration loss of the first leg portion 21 and the second leg portion 22 is suppressed, and the CI value can be suppressed low.

  The first excitation electrode 291 is formed on both main surfaces (one main surface 261 and the other main surface 262) of the first leg portion 21 and both side surfaces 28 of the second leg portion 22. Similarly, the second excitation electrode 292 is formed on both main surfaces (one main surface 261 and the other main surface 262) of the second leg portion 22 and both side surfaces 28 of the first leg portion 21.

  The first excitation electrode 291 and the second excitation electrode 292, the extraction electrodes 293 and 294, and the connection electrodes 295 and 296 of the tuning fork type crystal vibrating piece 2 are formed on the first leg portion 21 and the second leg portion 22 by metal deposition. A thin film formed by forming a chromium (Cr) layer on the chromium layer and forming a gold (Au) layer on the chromium layer. The thin film is formed on the entire surface of the substrate by a technique such as vacuum vapor deposition or sputtering, and then formed into a desired shape by metal etching by photolithography. The first excitation electrode 291, the second excitation electrode 292, and the extraction electrodes 293, 294 are formed by laminating chromium (Cr) and gold (Au) in this order. For example, chromium (Cr), silver ( The order may be Ag), chromium (Cr), gold (Au), chromium (Cr), chromium (Cr), silver (Ag), chromium (Cr).

  Further, the wide areas of the first leg portion 21 and the second leg portion 22 described above are formed on the one main surface 261 and the other main surface 262 of the distal end portions 211 and 221 of the first leg portion 21 and the second leg portion 22. In contrast, extraction electrodes 293 and 294 are formed on almost the entire surface. A metal film is formed on the upper surfaces of the extraction electrodes 293 and 294 formed in the wide regions of the first leg portion 21 and the second leg portion 22 of the one main surface 261 by ion irradiation such as laser beam irradiation or ion milling. The adjustment metal film (frequency adjustment weight) M3 obtained by adjusting the frequency of the tuning-fork type quartz vibrating piece 2 by reducing the mass of the tuning fork type crystal resonator element 2 is integrally formed with the extraction electrodes 293 and 294 in a slightly small area. .

  In the adjustment metal film M3, for example, the adjustment metal film M3 is formed by forming a formation portion of the adjustment metal film M3 in a desired shape on the extraction electrodes 293 and 294 in each region (wide region) by photolithography. The adjustment metal film M3 is plated on the forming portion by a technique such as electrolytic plating. Thereafter, an annealing treatment may be performed. When these metal films (adjustment metal film M3) are formed by plating, it is more practically desirable to form them simultaneously in the same process as the metal film M1 (M11, M12).

  The tuning-fork type crystal vibrating piece 2 configured as described above is measured after the frequency of each tuning-fork type crystal vibrating piece 2 is measured in the state of a wafer on which a large number of piezoelectric vibrating base plates are formed. The frequency is roughly adjusted by reducing the metal film M3 for adjustment of the crystal vibrating piece 2 by beam irradiation or by increasing it by partial vapor deposition.

  A piece of a tuning fork type crystal vibrating piece 2 (piezoelectric vibrating element plate) that has been subjected to coarse frequency adjustment and taken out of the wafer is a metal film M1 formed on the upper surface of the connection electrodes 295 and 296 on the one main surface 261 side. (M11, M12) and the electrode pads 32, 32 of the base 3 are ultrasonically bonded by the FCB method and mounted on the base 3.

  The tuning fork type quartz vibrating piece 2 mounted on the base 3 is finely adjusted by reducing the frequency of the frequency and then reducing the adjustment metal film M3 of the tuning fork type quartz vibrating piece 2 by beam irradiation or ion etching. The final frequency adjustment is performed.

  Thereafter, a lid (not shown) is joined to the base 3 on which the tuning-fork type crystal vibrating piece 2 having been subjected to the final frequency adjustment is mounted via a sealing member H by a technique such as heating and melting, and the tuning-fork type crystal. The resonator element 2 is hermetically sealed inside a housing constituted by a base 3 and a lid (not shown). Examples of the above-described hermetic sealing methods include seam welding, beam welding, and atmosphere heating.

  With the configuration described above, acoustic leak can be prevented more efficiently without hindering the downsizing of the tuning fork type crystal vibrating piece 2, and there is a problem that the tuning fork type crystal vibrating piece 2 is cracked by being strong against stress and external force. It can be prevented from occurring. In particular, it is possible to suppress vibration leakage (acoustic leakage) caused by vibration unbalance generated when exciting the tuning fork type crystal vibrating piece 2 without enlarging the length and area of the joint portion 23. Even when the tuning fork type crystal vibrating piece 2 is excited, vibration unbalance hardly occurs. In particular, in the first joining region 235 of the joining portion 23, the propagation of a part of vibration energy generated in the pair of first leg portion 21 and second leg portion 22 is also like an hourglass, and the inside of the piezoelectric vibration element plate ( Since the wall surface of the tuning fork-type crystal vibrating piece 2) is also combined with the spirally formed through holes 241 and 242 and can be cut off more efficiently, vibration leakage (acoustic leakage) is more efficiently performed. Therefore, it is possible to make the structure strong against stress and external force as a joint region with the outside.

  Moreover, the planar view shape of both ends T1, T2 (opening end) of the through holes 241 and 242 is a regular hexagon formed by six arc-shaped ridges, and two of the six ridges facing each other. The ridge sides 2411 and 2412 and the two ridge sides 2421 and 2422 are formed so as to be arranged in a direction orthogonal to the protruding direction of the first leg portion 21 and the second leg portion 22. For this reason, it is possible to give uniformity to the corners that are the connection points of the ridges and the ridges that are the end portions T1 and T2 (opening ends) of the through holes 241 and 242. By being an obtuse angle of 120 ° and 90 ° or more, stress concentration at each corner becomes difficult to occur, and the occurrence of cracks at each corner is suppressed. Furthermore, since it is a substantially regular polygonal shape composed of six arc-shaped ridge sides, the stress transmitted to each ridge side is evenly distributed. As a result, not only the strength at both end portions T1, T2 (open end portions) of the through holes 241 and 242 is improved, but the configuration of both end portions T1, T2 (open end portions) of the through holes 241, 242 is spiral. By combining with the wall surface S1, it is possible to synergistically eliminate stress concentration and suppress the occurrence of further cracks, and it is even more preferable to let the propagation of vibration energy escape. Furthermore, two ridge sides 2411 and 2412 and two ridge sides 2421 and 2422 facing each other among the six ridge sides of the through holes 241 and 242 are orthogonal to the protruding directions of the first leg portion 21 and the second leg portion 22. They are arranged in the direction. For this reason, even if bending fluctuation occurs with respect to the first leg portion 21 and the second leg portion 22 of the tuning-fork type crystal vibrating piece 2, the stress of this bending fluctuation is close to the leg portion of the two opposing ridge sides. By being supported by the ridges 2411 and 2421 on the other side, stress concentration is less likely to occur, and the occurrence of cracks at this portion is further suppressed. The occurrence of this crack reduces not only the impact of dropping the tuning fork type crystal vibrating piece 2 on the base 3 but also the influence when the tuning fork type crystal vibrating piece 2 is mounted on the base 3. Can do.

  Further, between the front and back main surfaces (one main surface) via the ridge or side end surface of the tuning fork type crystal vibrating piece 2 around the fork portion 253 or the ridge portion or side end surface of the other base 25 adjacent to the fork portion 253. 261 and the other main surface 262) are not required to have a wiring structure for extending the extraction electrodes 293 and 294, and therefore, it is possible to achieve a configuration with stable electrical connectivity in which disconnection or the like hardly occurs. Further, a part of the extraction electrodes 293 and 294 is in contact with the fork portion 253 so as not to be drawn between the base end portion 212 and the base end portion 222 of the pair of leg portions (the first leg portion 21 and the second leg portion 22). Therefore, the lead-out electrodes 293 and 294 formed on the main surface of the base portion 25 of the tuning-fork type crystal vibrating piece 2 can be easily designed with a more simplified wiring pattern, so that the tuning-fork type quartz crystal Miniaturization of the base 25 of the resonator element 2 can be realized at the same time.

  Further, by using the metal film M1 (M11, M12) as a plating bump for the joint portion 23, the displacement and protrusion of the electrode pads 32 and 32 and the connection electrodes 295 and 296 that are further reduced in size occur. Absent. The tuning-fork type crystal vibrating piece 2 can be stably electromechanically joined to the base 3 by the metal film M1 (M11, M12). Specifically, by using the metal film M1 (M11, M12) as a plating bump, the tuning fork type crystal vibrating piece 2 can be used as a plating bump before the tuning fork type crystal vibrating piece 2 is mounted on the outside (base 3). Metal films M1 (M11, M12) can be formed. As a result, since the metal film M1 (M11, M12) as a plating bump is always formed at a desired formation position of the tuning fork type crystal vibrating piece 2, for example, to the outside (base 3) of the tuning fork type crystal vibrating piece 2 Even if the mounting position is shifted from the desired position, it is possible to prevent the tuning-fork type crystal vibrating piece 2 from being mounted on the outside (base 3) in a state where the bump is shifted. The tuning-fork type crystal vibrating piece 2 can be mounted. Further, since the metal film M1 (M11, M12) having a rougher surface roughness and a smaller flat area than the connection electrodes 295, 296 is used, the metal film M1 (M11, M12) is more stable with respect to the electrode pads 32, 32. Thermal diffusion bonding is performed in a state, and electromechanical bonding is stabilized.

  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.

  The present invention can be applied to a piezoelectric vibration device such as a tuning fork type crystal resonator.

DESCRIPTION OF SYMBOLS 1 Tuning fork type crystal resonator 2 Tuning fork type crystal resonator element 21 First leg portion 211 Tip portion 212 Base end portion 22 Second leg portion 221 Tip portion 222 Base end portion 23 Joint portion 231 Short side portion 232 Long side portion 233 Tip portion 234 Folded portion 235 First joint region 236 Second joint region 241, 242 Through hole 25 Base 251 One end surface 252 Other end surface 253 Fork portion 254 Side surface 255 Constricted portion 261 One main surface 262 Other main surface 27 Groove portion 28 Side surface 291 , 292 Excitation electrodes 293, 294 Extraction electrodes 295, 296 Connection electrodes 297, 298 Other ends 3 of the extraction electrodes 3 Base 30 Bank portion 31 Step portion 32 Electrode pad 33 Terminal electrode 34 Metal film layer D1 Minimum length D2, D3 Length D4 Total shortest length H Sealing member M1 (M11, M12) Metal film M3 Adjustment metal film P Center line P1 Base point P2 Shortest point Q1, Q2 Line segment S1 Inside the both end portions T3 tuning-fork type crystal vibrating piece of the wall T1, T2 through hole of hole

Claims (3)

In tuning fork type piezoelectric vibrating piece,
The piezoelectric vibration element plate is composed of a pair of legs that are made of crystal and are vibrating parts, and a base part that protrudes from the legs,
The pair of leg portions are juxtaposed to protrude from one end surface of the base portion, and between the pair of leg portions, a fork portion is formed at an intermediate position in the width direction of the one end surface of the base portion,
In the base, a pair of through holes are formed along one end surface of the base, and a joining region that joins to the outside is provided on the other end surface facing the one end surface of the base.
The pair of through holes are formed in a state in which the mutual (reciprocal) through holes are not in contact with each other at positions closer to the center line in the width direction of the base than the base ends of the pair of legs.
In the through hole, the plane area of the through hole gradually decreases from both end portions of the through hole on the front and back main surfaces of the piezoelectric vibration element plate toward the inside of the piezoelectric vibration element plate, and A tuning-fork type piezoelectric vibrating piece, wherein a wall surface is formed in a spiral shape, and the shape of the through hole in a plan view is formed in a substantially regular polygonal shape constituted by five or more arcuate ridges. In the tuning fork type piezoelectric vibrating piece according to claim 1,
The through hole has a substantially regular polygonal shape with an even number of ridge sides, and two opposing ridge sides of the substantially regular polygon are arranged in a direction perpendicular to the protruding direction of the leg portion. Tuning fork type piezoelectric vibrating piece In tuning fork type piezoelectric vibrator,
A tuning fork type piezoelectric vibrator comprising the tuning fork type piezoelectric vibrating piece according to claim 1 or 2 provided inside a housing of the tuning fork type piezoelectric vibrator and hermetically sealed.

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