JP2012195918A - Piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device capable of preventing increase of capacitance.SOLUTION: A piezoelectric device 100 includes: a piezoelectric vibration frame 10 provided with a piezoelectric vibration piece 101 having a pair of excitation electrodes 102a formed on both main surfaces Me and Mi and a frame body 104 surrounding the piezoelectric vibration piece and having a pair of extraction electrodes 103a and 103b extracted from the excitation electrodes formed on one main surface Mi; a first plate 12 having a first end face M1 joined to one main surface of the frame body of the piezoelectric vibration frame, a mounting surface M3 on the opposite side of the first end face, a pair of mounting terminals 125a and 125b formed by being extended from the mounting surface to the first end face and joined to the extraction electrodes, and a first step part 123 formed on the inner side of the entire periphery of the first end face and recessed from the first end face; and a joining member LG arranged at the first step part of the first plate, to join the piezoelectric vibration frame and the first plate.

Description

  The present invention relates to a surface mount type piezoelectric device including a piezoelectric vibration frame having a frame.

  As a piezoelectric device such as a piezoelectric vibrator or a SAW filter, a surface mount type (SMD) type package is mainly used. As the package, a crystal package using a piezoelectric material such as crystal formed by etching or a glass package using glass has been proposed.

  For example, in the piezoelectric device disclosed in Patent Document 1, lead electrodes are formed on the entire surface of both surfaces of the frame of the piezoelectric vibration frame, and the entire surface of the lid portion that forms the package and the surface that is bonded to the piezoelectric vibration frame of the base portion. A metal film for bonding is formed on each. And the piezoelectric device by which the inside was airtight was manufactured by joining an extraction electrode and the metal film for joining with a metal-type brazing material.

WO2007 / 023685

  However, in the piezoelectric device disclosed in Patent Document 1, if the electrical brazing and the airtight joining are combined with the same metal brazing material, the capacitance of the piezoelectric device may increase. Therefore, it becomes difficult to change the frequency depending on the application of the piezoelectric device, and reliability cannot be guaranteed.

  An object of the present invention is to provide a piezoelectric device capable of preventing an increase in capacitance.

  A piezoelectric device according to a first aspect includes a piezoelectric vibrating piece in which a pair of excitation electrodes are formed on both main surfaces, and a frame in which a pair of extraction electrodes are formed on the entire surface of one main surface so as to surround the piezoelectric vibrating piece. A piezoelectric vibration frame having a body, a first end surface joined to one main surface of the frame of the piezoelectric vibration frame, a mounting surface opposite to the first end surface, and extending from the mounting surface to the entire surface of the first end surface. A first plate having a pair of mounting terminals joined to the electrodes and a first step portion formed inside the entire circumference of the first end surface and recessed from the first end surface; and a piezoelectric element disposed on the first step portion of the first plate A bonding material for bonding the vibration frame and the first plate.

  In the piezoelectric device according to the second aspect, the pair of lead electrodes formed on the frame of the piezoelectric vibration frame are formed apart from each other by a predetermined distance, and the pair of mounting terminals formed on the first end surface of the base portion are separated from each other by a predetermined distance. Formed.

  In the piezoelectric device according to the third aspect, the piezoelectric vibration frame and the first plate are bonded by both the bonding material and the eutectic metal bonding or the anodic bonding.

  In the piezoelectric device according to the fourth aspect, the piezoelectric vibrating frame further includes a connecting portion that connects the piezoelectric vibrating piece and the frame, and a through opening between the piezoelectric vibrating piece and the frame, and the other main surface of the piezoelectric vibrating piece. The extraction electrode drawn out from the excitation electrode formed in the step is formed to extend to one main surface of the frame body through the connecting portion and the through opening.

  In the piezoelectric device according to the fifth aspect, the piezoelectric vibration frame is formed with a first castellation that is recessed from the outer periphery, and the extraction electrode that is extracted from the excitation electrode formed on the other main surface of the piezoelectric vibration piece is the first castellation. It is formed to extend to one main surface of the frame body.

  A piezoelectric device according to a sixth aspect includes a second plate having a second end surface joined to the other main surface of the frame body of the piezoelectric vibration frame.

  In the piezoelectric device according to the seventh aspect, a metal film is formed on the second end surface of the second plate, and an extraction electrode drawn from the excitation electrode formed on the other main surface of the piezoelectric vibrating piece is formed on the other main surface of the frame. The formed metal film of the second plate and the extraction electrode formed on the other main surface of the piezoelectric vibration frame are bonded by eutectic metal bonding or anodic bonding.

  In the piezoelectric device according to the eighth aspect, a second castellation that is recessed from the outer periphery is formed on the first plate, and the mounting terminal is formed to extend from the mounting surface to the first end surface via the second castellation.

  In the piezoelectric device according to the ninth aspect, the first plate has a first recess recessed from the first step portion, and the second plate is further recessed from the second step portion and the second step portion recessed from the second end surface. There are two recesses, and the bonding material is disposed in the first step portion and the second step portion.

  In the piezoelectric device according to the tenth aspect, the bonding material is low-melting glass or polyimide resin.

  In the piezoelectric device according to the eleventh aspect, the frame is formed thicker than the thickness of the piezoelectric vibrating piece.

  The present invention provides a piezoelectric device that can prevent an increase in capacitance by using different materials for electrical bonding and hermetic bonding.

2 is an exploded perspective view of a first crystal resonator 100. FIG. FIG. 4A is a plan view of the crystal frame 10 viewed from the + Y′-axis side. (B) is a transparent view of the crystal frame 10 as viewed from the + Y′-axis side. (A) is sectional drawing of the base part 12 in the AA cross section of FIG. FIG. 4B is a plan view of the base portion 12 viewed from the + Y ′ axis side. (A) is sectional drawing of the lid part 11 in the AA cross section of FIG. FIG. 5B is a plan view of the lid portion 11 as viewed from the −Y′-axis side. It is AA sectional drawing of FIG. 3 is a flowchart showing a method for manufacturing the first crystal unit 100. It is a top view of the lid wafer 11W. FIG. 6 is a plan view of a crystal wafer 10W viewed from the + Y′-axis side. It is a transparent view of the quartz crystal wafer 10W viewed from the + Y′-axis side. It is a top view of the base wafer 12W. (A) is BB sectional drawing in FIGS. 7-10, and is the figure which showed the state in which eutectic metal EC was mounted in the groove part for eutectic metals. FIG. 7B is a cross-sectional view taken along the line B-B in FIGS. 7 to 10, illustrating a state in which the lid wafer 11 </ b> W, the crystal wafer 10 </ b> W, and the base wafer 12 </ b> W are bonded by the eutectic metal EC. 4 is an exploded perspective view of a second crystal resonator 200. FIG. FIG. 6 is a transparent view of the crystal frame 20 viewed from the + Y′-axis side. It is CC sectional drawing of FIG. 5 is a flowchart showing a method for manufacturing the second crystal unit 200.

  In this specification, an AT-cut crystal frame is used as the piezoelectric vibration frame. In other words, the AT-cut crystal frame has a main surface (YZ plane) inclined with respect to the Y axis of the crystal axis (XYZ) from the Z axis to the Y axis direction by 35 degrees 15 minutes with respect to the X axis. Therefore, the new tilted axes are used as the Y ′ axis and the Z ′ axis with reference to the X axis direction of the AT-cut crystal frame. That is, in the present embodiment, the description will be made assuming that the longitudinal direction of the crystal frame is the X-axis direction, the height direction of the crystal frame is the Y′-axis direction, and the direction perpendicular to the X-axis direction and the Y′-axis direction is the Z′-axis direction.

(First embodiment)
<Overall Configuration of First Crystal Resonator 100>
The first crystal unit 100 is a surface mount type and is used by being mounted on a printed circuit board or the like. The overall configuration of the first crystal unit 100 will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the first crystal unit 100.

  As shown in FIG. 1, the first crystal unit 100 includes a lid portion 11 having a lid recess 111, a base portion 12 having a base recess 121, and a crystal frame 10 sandwiched between the lid portion 11 and the base portion 12. With.

<< Configuration of Crystal Frame 10 >>
First, the configuration of the crystal frame 10 will be described with reference to FIGS. 1 and 2. 2A is a plan view of the crystal frame 10 viewed from the + Y ′ axis side, and FIG. 2B is a transparent view of the crystal frame 10 viewed from the + Y ′ axis side. As shown in FIG. 1, the crystal frame 10 is formed of an AT-cut quartz material, and has a surface Me on the + Y ′ side and a back surface Mi on the −Y ′ side. The crystal frame 10 includes a crystal vibrating unit 101 and a frame body 104 surrounding the crystal vibrating unit 101. A through opening 108 that penetrates from the front surface Me to the back surface Mi is formed between the crystal vibrating portion 101 and the frame body 104. Portions where the through opening 108 is not formed are connecting portions 105 a and 105 b that connect the crystal vibrating portion 101 and the frame body 104. Here, the connecting portion 105a is connected to the + X-axis side (−Z′-axis side) of the crystal vibrating portion 101, and the connecting portion 105b is connected to the −X-axis side (+ Z′-axis side) of the crystal vibrating portion 101.

  Further, castellations 106a and 106b when the through holes CH (see FIGS. 8 and 9) are formed are formed on both sides in the X-axis direction of the crystal frame 10, respectively. Specifically, a castellation 106 a is formed on the + X axis side of the crystal frame 10, and a castellation 106 b is formed on the −X axis side of the crystal frame 10.

  As shown in FIG. 2A, the crystal frame 10 has a first excitation electrode 102 a formed on the surface Me of the crystal vibrating part 101. In addition, a first extraction electrode 103 a that is extracted from the first excitation electrode 102 a is formed on the surface Me of the crystal frame 10. The first extraction electrode 103a is formed all around the frame body 104 from the crystal vibrating part 101 through the connecting part 105a. Further, the first extraction electrode 103a formed on the surface Me of the crystal frame 10 is extracted to the back surface Mi of the crystal frame 10 through the castellation 106a (see FIG. 2B).

  As shown in FIG. 2B, the crystal frame 10 has the second excitation electrode 102 b formed on the back surface Mi of the crystal vibrating portion 101. Further, a second extraction electrode 103b extracted from the second excitation electrode 102b is formed on the back surface Mi of the crystal frame 10. The second extraction electrode 103b is formed all around the frame body 104 from the quartz crystal vibrating portion 101 through the connecting portion 105b. Further, the second extraction electrode 103b formed on the back surface Mi of the crystal frame 10 is extracted to the surface Me of the crystal frame 10 through the castellation 106b (see FIG. 2A).

  Here, for the first excitation electrode 102a, the second excitation electrode 102b, the first extraction electrode 103a, and the second extraction electrode 103b, for example, a chromium (Cr) layer is used as a base, and a gold (Au) layer is formed on the upper surface of the chromium layer. Is used. The chromium layer has a thickness of, for example, 0.05 μm to 0.1 μm, and the gold layer has a thickness of, for example, 0.2 μm to 2 μm.

  Further, as shown in FIG. 2, on the front surface Me and the back surface Mi, the first extraction electrode 103a and the second extraction electrode 103b are formed apart from each other by a gap SP having a predetermined width. Thereby, it can be ensured that the first extraction electrode 103a and the second extraction electrode 103b do not short-circuit.

<< Configuration of Base Unit 12 >>
Next, the structure of the base part 12 is demonstrated, referring FIG.1 and FIG.3. 3A is a cross-sectional view of the base portion 12 in the AA cross section of FIG. 1, and FIG. 3B is a plan view of the base portion 12 viewed from the + Y′-axis side. As shown in FIG. 1, the base portion 12 is made of glass or quartz material, and has a first end face M1 on the outer periphery of the + Y ′ side face. Castellations 126a and 126b when through holes BH (see FIG. 10) are formed are formed on both sides of the base portion 12 in the X-axis direction. Specifically, a castellation 126 a is formed on the + X axis side of the base portion 12, and a castellation 126 b is formed on the −X axis side of the base portion 12.

  As shown in FIG. 3A, the mounting terminal 125a is formed on the + X axis side of the mounting surface M3, and the mounting terminal 125b is formed on the −X axis side of the mounting surface M3. The mounting terminal 125a is formed to extend to the first end face M1 through the castellation 126a, and the mounting terminal 125b is formed to extend to the first end face M1 through the castellation 126b.

  Further, a first step portion 123 that is recessed from the first end surface M1 in the Y′-axis direction is formed inside the entire circumference of the first end surface M1, and a first step in the Y′-axis direction is formed inside the first step portion 123. A base recess 121 that is recessed from the stepped portion 123 is formed. Further, a low melting point glass LG as a bonding material for bonding the crystal frame 10 and the base portion 12 so as to be airtight is disposed in the first step portion 123.

  The low melting point glass LG includes lead-free vanadium-based glass that melts at 350 ° C. to 410 ° C. Vanadium-based glass is in the form of a paste with a binder and a solvent added, and is melted and then solidified to adhere to other members. In addition, this vanadium-based glass has high reliability such as airtightness at the time of bonding, water resistance and moisture resistance. Furthermore, the thermal expansion coefficient of vanadium glass can be flexibly controlled by controlling the glass structure.

  As shown in FIG. 3B, the second extraction electrode 103b (see FIG. 2B) formed on the back surface Mi (see FIG. 2B) of the frame body 104 of the crystal frame 10 is used. Correspondingly, mounting terminals 125 b are formed around the entire first end face M <b> 1 of the base portion 12. Further, the mounting terminal 125b is formed from the mounting surface M3 of the base portion 12 to the first end surface M1, and the first end surface M1 is formed away from the mounting terminal 125a with a gap SP having a predetermined width.

<< Configuration of Lid Part 11 >>
Next, the structure of the lid part 11 is demonstrated, referring FIG.1 and FIG.4. 4A is a cross-sectional view of the lid portion 11 in the AA cross section of FIG. 1, and FIG. 4B is a plan view of the lid portion 11 viewed from the −Y′-axis side. As shown in FIG. 1, the lid portion 11 is made of glass or quartz material, and has a second end face M <b> 2 on the outer periphery of the −Y ′ side face.

  As shown in FIG. 4A, a second stepped portion 113 that is recessed from the second end surface M2 in the Y′-axis direction is formed inside the entire circumference of the second end surface M2, and A lid recess 111 that is recessed from the second stepped portion 113 in the Y′-axis direction is formed inside. Further, a low melting point glass LG as a bonding material for bonding the lid portion 11 and the crystal frame 10 so as to be hermetically sealed is disposed on the second stepped portion 113.

  As shown in FIG. 4B, the first extraction electrode 103a (see FIG. 2A) formed on the surface Me (see FIG. 2A) of the frame body 104 of the crystal frame 10 is applied. Correspondingly, a metal film 112 is formed on the entire periphery of the second end face M <b> 2 of the lid portion 11.

<< Assembly of First Crystal Resonator 100 >>
Finally, assembly of the first crystal unit 100 will be described with reference to FIGS. 1 and 5. 5 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 1 and 5, the lid portion 11 is bonded to the + Y′-axis side of the crystal frame 10, and the base portion 12 is bonded to the −Y′-axis side of the crystal frame 10.

  That is, the metal film 112 formed on the second mating surface M2 of the lid portion 11 and the first extraction electrode 103a formed on the surface Me of the frame body 104 of the crystal frame 10 are joined. Similarly, the mounting terminal 125b formed on the first end face M1 of the base portion 12 and the second extraction electrode 103b formed on the back surface Mi of the frame body 104 of the crystal frame 10 are joined. The metal film 112 and the first extraction electrode 103a, and the mounting terminal 125b and the second extraction electrode 103b are joined by a eutectic metal. As the eutectic metal, a gold silicon (Au 3.15Si) alloy, a gold germanium (Au12Ge) alloy, or a gold tin (Au20Sn) alloy is used. The eutectic metal bonding will be described in detail with reference to FIG.

  Here, the mounting terminal 125a formed up to the first end face M1 of the base portion 12 through the castellation 126a and the first extraction electrode 103a formed on the back surface Mi of the frame body 104 of the crystal frame 10 are electrically conducted. Similarly, the mounting terminal 125b formed up to the first end face M1 of the base portion 12 through the castellation 126b and the second extraction electrode 103b formed on the back surface Mi of the frame body 104 of the crystal frame 10 are electrically conducted. That is, the mounting terminal 125a formed on the base portion 12 and the first excitation electrode 102a of the crystal frame 10 are conductive, and the mounting terminal 125b formed on the base portion 12 and the second excitation electrode 102b of the crystal frame 10 are conductive. Is done. As a result, when an alternating voltage (potential alternating between positive and negative) is applied to the mounting terminals 125a and 125b, the quartz crystal vibrating portion 101 can vibrate in thickness.

  On the surface Me of the crystal frame 10, the bonded metal film 112 and the first extraction electrode 103a are formed apart from the second extraction electrode 103b so as to form a gap SP having a predetermined width, so the first extraction electrode 103a. And the second extraction electrode 103b are insulated. Similarly, on the back surface Mi of the crystal frame 10, the mounting terminal 125b and the second extraction electrode 103b that are joined are formed apart from the first extraction electrode 103a so as to form a gap SP having a width W1. The extraction electrode 103a and the second extraction electrode 103b are insulated.

  Further, the lid portion 11 and the crystal frame 10 are further joined by the low melting point glass LG disposed in the second step portion 113 of the lid portion 11. Similarly, the crystal frame 10 and the base portion 12 are further joined by the low melting point glass LG disposed in the first step portion 123 of the base portion 12.

  As a result, a cavity CT is formed in which the quartz crystal vibrating portion 101 of the quartz frame 10 is sealed. The cavity CT is filled with nitrogen gas or is evacuated.

  That is, in the first embodiment, electrical bonding is performed by eutectic metal EC (see FIG. 11), and hermetic bonding is performed by low melting point glass LG. In other words, the first crystal unit 100 of the first embodiment can prevent an increase in capacitance by using different materials for electrical bonding and airtight bonding.

<Method for Manufacturing First Crystal Resonator 100>
FIG. 6 is a flowchart showing a method for manufacturing the first crystal unit 100. In FIG. 6, the manufacturing step S11 of the lid portion 11, the manufacturing step S12 of the crystal frame 10, and the manufacturing step S13 of the base portion 12 can be performed separately and in parallel. FIG. 7 is a plan view of the lid wafer 11W. FIG. 8 is a plan view of the quartz-crystal wafer 10W viewed from the + Y′-axis side. FIG. 9 is a transparent view of the crystal wafer 10W viewed from the + Y′-axis side. FIG. 10 is a plan view of the base wafer 12W.

In step S11, the lid part 11 is manufactured. Step S11 includes steps S111 to S113.
In step S111, as shown in FIG. 7, hundreds to thousands of lid concave portions 111 and second stepped portions 113 (see FIG. 4A) are formed on the lid wafer 11W of a quartz plate having a uniform thickness. The The lid recess 11 and the second step 113 are formed on the lid wafer 11W by etching or machining, and the second end face M2 is formed on the outer periphery of the lid recess 111 and the second step 113. At the same time, eutectic metal grooves 115 for positioning the spherical eutectic metal EC are formed at the four corners of the lid portion 11 in step S14 described later. That is, the eutectic metal groove 115 is formed in the middle of the four lid portions 11 adjacent to each other.

  In step S112, as shown in FIG. 7, the metal film 112 is formed on the second end face M2 of the lid wafer 11W by sputtering or vacuum deposition. Here, the metal film 112 is not formed at the locations 114 on both sides in the X-axis direction of the lid portion 11 so as to correspond to the shape of the first extraction electrode 103a formed in step S122 described later.

  In step S113, as shown in FIG. 7, the low melting point glass LG is formed on the second step portion 113 (see FIG. 4A) of the lid wafer 11W by screen printing. Thereafter, the low-melting glass LG is temporarily cured, so that the low-melting glass LG is disposed on the second step portion 113 of the lid wafer 11W.

In step S12, the crystal frame 10 is manufactured. Step S12 includes steps S121 and S122.
In step S121, as shown in FIGS. 8 and 9, the outer shape of the plurality of crystal frames 10 is formed on the uniform crystal wafer 10W by etching. That is, the crystal vibrating portion 101, the frame body 104, and the through opening 108 are formed. At the same time, through holes CH having rounded rectangular shapes are formed on both sides of each crystal frame 10 in the X-axis direction so as to penetrate the crystal wafer 10W. When the through hole CH is divided in half, one castellation 106a, 106b (see FIG. 2) is obtained. At the same time, eutectic metal grooves 109 for positioning the spherical eutectic metal EC are formed at the four corners of the crystal frame 10 in step S14 described later. That is, the eutectic metal groove 109 is formed in the middle of the four crystal frames 10 adjacent to each other.

  In step S122, first, metal layers are formed on both surfaces of the quartz wafer 10W and the through holes CH by sputtering or vacuum deposition. Then, a photoresist is uniformly applied on the entire surface of the metal layer. Thereafter, the pattern of the first excitation electrode 102a, the second excitation electrode 102b, the first extraction electrode 103a, and the second extraction electrode 103b drawn on the photomask is exposed to the crystal wafer 10W using an exposure apparatus (not shown). The Next, the metal layer exposed from the photoresist is etched. As a result, as shown in FIGS. 8 and 9, the first excitation electrode 102a, the second excitation electrode 102b, the first extraction electrode 103a, and the second extraction electrode 103b are formed on both surfaces of the quartz wafer 10W, and the through hole CH Are formed with a first extraction electrode 103a and a second extraction electrode 103b.

  Here, as shown in FIG. 8, in each crystal frame 10, the first extraction electrode 103a and the second extraction electrode 103b are insulated by a gap SP having a predetermined width on the −X axis side on the surface Me. On the other hand, as shown in FIG. 9, in each crystal frame 10, the first extraction electrode 103a and the second extraction electrode 103b are insulated by a gap SP having a predetermined width on the + X axis side on the back surface Mi. Thereby, it can be ensured that the first extraction electrode 103a and the second extraction electrode 103b do not short-circuit.

In step S13, the base portion 12 is manufactured. Step S13 includes steps S131 to S133.
In step S131, as shown in FIG. 10, hundreds to thousands of base recesses 121 and first stepped portions 123 (see FIG. 3A) are formed on a crystal wafer base plate 12W having a uniform thickness. Is done. A base recess 121 and a first stepped portion 123 are formed on the base wafer 12W by etching or machining, and a first end face M1 is formed on the outer periphery of the base recessed portion 121 and the first stepped portion 123. At the same time, rounded rectangular through holes BH are formed on both sides of each base portion 12 in the X-axis direction so as to penetrate the base wafer 12W. When the through hole BH is divided in half, one castellation 126a, 126b (see FIG. 1) is obtained. At the same time, eutectic metal grooves 128 for positioning the spherical eutectic metal EC are formed at the four corners of the base portion 12 in step S14 described later. That is, the eutectic metal groove 128 is formed in the middle of the four base portions 12 adjacent to each other.

  In step S132, a pair of mounting terminals 125a and 125b are formed on the first end surface M1 and the mounting surface M3 of the base portion 12 by sputtering and etching methods (see FIG. 1). Here, the mounting terminal 125b is formed in the same shape as the second extraction electrode 103b on the back surface Mi of the crystal wafer 10W formed in step S122. That is, the mounting terminal 125b is insulated from the mounting terminal 125a by the gap SP having the width W1 (see FIG. 3).

  In step S133, as shown in FIG. 10, the low melting point glass LG is formed on the first step portion 123 (see FIG. 3A) of the base wafer 12W by screen printing. Thereafter, the low-melting glass LG is temporarily cured, so that the low-melting glass LG is disposed on the first step portion 123 of the base wafer 12W.

  In step S14, a plurality of spherical eutectic metals EC are placed in the eutectic metal grooves as shown in FIG. FIG. 11A is a cross-sectional view taken along the line BB in FIGS. 7 to 10 and shows a state in which the eutectic metal EC is placed in the eutectic metal groove. As shown in FIG. 11A, the base wafer 12W is placed on a table (not shown), and the eutectic metal groove 128 of the base wafer 12W and the eutectic metal groove 109 on the surface Me of the crystal wafer 10W are spherical. The eutectic metal EC is placed.

  In step S15, the lid wafer 11W, the crystal wafer 10W, and the base wafer 12W are bonded together by the eutectic metal EC and the low melting point glass LG. FIG. 11B is a cross-sectional view taken along the line B-B in FIGS. 7 to 10 and shows a state in which the lid wafer 11W, the crystal wafer 10W, and the base wafer 12W are bonded by the eutectic metal EC. Here, the eutectic metal EC is dissolved in a vacuum or in an inert atmosphere. The melted eutectic metal EC is capillarized between the metal film 112 of the lid wafer 11W and the first extraction electrode 103a on the surface Me of the quartz wafer 10W, and the second extraction electrode 103b on the back surface Mi of the quartz wafer 10W and the base wafer. It flows between the 12W mounting terminal 125b. Thereby, the surfaces of the metal film 112, the first extraction electrode 103a, the second extraction electrode 103b, and the mounting terminal 125b are wetted. Further, since the distances between adjacent eutectic metal grooves are substantially equal, the surfaces of the metal film 112, the first extraction electrode 103a, the second extraction electrode 103b, and the mounting terminal 125b can be sufficiently wetted.

  Further, the lid wafer 11W, the crystal wafer 10W, and the base wafer 12W are more reliably bonded by the low melting point glass LG (see FIG. 5). In the first crystal unit 100, electrical bonding is performed using eutectic metal EC, and hermetic bonding is performed using low-melting glass LG. That is, the first crystal unit 100 can prevent an increase in capacitance by using different materials for electrical bonding and airtight bonding.

  In step S16, the bonded lid wafer 11W, crystal wafer 10W, and base wafer 12W are individually cut. In the cutting process, the first crystal unit 100 is unitized along the one-dot chain line scribe line SL shown in FIGS. 7 to 10 using a dicing apparatus using a laser or a dicing apparatus using a cutting blade. As a piece. Thereby, hundreds to thousands of first crystal units 100 are manufactured.

(Second Embodiment)
<Overall Configuration of Second Crystal Resonator 200>
The overall configuration of the second crystal unit 200 will be described with reference to FIGS. FIG. 12 is an exploded perspective view of the second crystal unit 200. In the second embodiment, the same components as those in the first embodiment will be described with the same reference numerals.

  As shown in FIG. 12, the second crystal unit 200 includes a lid part 21 having a first second step part 213, a base part 22 having a first step part 223, a lid part 21 and a base part 22. And a sandwiched crystal frame 20.

<< Configuration of Crystal Frame 20 >>
The configuration of the crystal frame 20 will be described in detail with reference to FIGS. FIG. 13 is a transparent view of the crystal frame 20 viewed from the + Y′-axis side. The quartz frame 20 is formed of an AT-cut quartz material and has a + Y′-side surface Me and a −Y′-side back surface Mi. The crystal frame 20 includes a crystal vibrating part 101 and a frame body 204 that surrounds the crystal vibrating part 101, and a through opening 108 that penetrates from the front surface Me to the back surface Mi is formed between the crystal vibrating part 101 and the frame body 204. Is done. Portions where the through opening 108 is not formed are connecting portions 105 a and 105 b that connect the crystal vibrating portion 101 and the frame body 204.

  In the crystal frame 10, the first excitation electrode 102 a and the first extraction electrode 203 a that is extracted from the first excitation electrode 102 a are formed on the surface Me of the crystal vibration unit 101. The first extraction electrode 203a is formed to extend from the crystal vibrating portion 101 to the + X axis side of the back surface Mi of the frame body 204 through the connecting portion 105a and the through opening 108. As shown in FIG. 13, the first extraction electrode 203 a extending to the back surface Mi of the frame body 204 is formed so as to cover almost half of the frame body 204 on the + X axis side.

  Further, as shown in FIG. 13, the crystal frame 20 has the second excitation electrode 102b and the second extraction electrode 203b extracted from the second excitation electrode 102b formed on the back surface Mi of the crystal vibration unit 101. The second extraction electrode 203b is formed so as to cover approximately half of the rear surface Mi of the frame body 104 on the −X-axis side from the crystal vibrating portion 101 through the connecting portion 105b.

  Note that, on the rear surface Mi of the frame 204, the first extraction electrode 203a and the second extraction electrode 203b are formed apart so as to form a gap SP having a predetermined width. Thereby, it can be ensured that the first extraction electrode 203a and the second extraction electrode 203b are not short-circuited.

<< Configuration of Base Unit 22 >>
As shown in FIG. 12, the base portion 22 is formed of glass or a quartz material, and has a first step portion 223 and a first end face M <b> 1 formed on the outer periphery of the first step portion 223. On both sides of the base portion 22 in the X-axis direction, castellations 126a and 126b when the through holes BH (see FIG. 10) are formed are formed.

  Mounting terminals 225a and 225b are formed on both sides of the mounting surface M3 of the base portion 22 on the X axis. The mounting terminal 225a is formed so as to cover almost half of the first end face M1 on the + X axis side via the castellation 126a, and the mounting terminal 225b is formed on the −X axis side of the first end face M1 via the castellation 126b. It is formed to cover almost half.

  Note that, on the first end face M1 of the base portion 22, the mounting terminal 225a and the mounting terminal 225b are formed apart so as to form a gap SP having a predetermined width. Thereby, it is possible to ensure that the mounting terminal 225a and the mounting terminal 225b are not short-circuited.

  Further, the low melting point glass LG as a bonding material for bonding the crystal frame 20 and the base portion 22 circulates around the first stepped portion 223 inside the first end face M1 of the base portion 22, that is, in the first stepped portion 223. Are arranged as follows.

<< Configuration of lid portion 21 >>
As shown in FIG. 12, the lid portion 21 is made of glass or quartz material, and the second end surface M2 formed on the outer periphery of the surface on the −Y ′ side and the second stepped portion 213 recessed from the second end surface. And have.

<< Assembly of First Crystal Resonator 100 >>
Finally, the assembly of the first crystal unit 100 will be described with reference to FIGS. 14 is a cross-sectional view taken along the line CC of FIG. As shown in FIG. 14, the lid portion 21 is bonded to the + Y′-axis side of the crystal frame 20, and the base portion 22 is bonded to the −Y′-axis side of the crystal frame 20.

  That is, the second mating surface M2 of the lid portion 21 and the surface Me of the frame body 204 of the crystal frame 20 are joined by the low melting point glass LG that is a joining material. On the other hand, the mounting terminals 225a and 225b formed on the first end face M1 of the base portion 22 and the first extraction electrode 103a and the second extraction electrode 103b formed on the back surface Mi of the frame body 204 of the crystal frame 20 are eutectic metal. Are joined together. As the eutectic metal, a gold silicon (Au 3.15Si) alloy, a gold germanium (Au12Ge) alloy, or a gold tin (Au20Sn) alloy is used. Since the bonding using the eutectic metal has been described with reference to FIG.

  Here, the mounting terminal 225a formed up to the first end face M1 of the base portion 22 through the castellation 126a and the first extraction electrode 203a formed on the back surface Mi of the frame body 204 of the crystal frame 20 are electrically conducted. Similarly, the mounting terminal 225b formed up to the first end face M1 of the base portion 22 through the castellation 126b and the second extraction electrode 203b formed on the back surface Mi of the frame body 204 of the crystal frame 20 are electrically conducted. That is, the mounting terminal 225a formed on the base portion 22 and the first excitation electrode 102a of the crystal frame 20 are conductive, and the mounting terminal 225b formed on the base portion 22 and the second excitation electrode 102b of the crystal frame 20 are conductive. Is done. As a result, when an alternating voltage (a potential that alternates between positive and negative) is applied to the mounting terminals 225a and 225b, the quartz crystal vibrating portion 101 can vibrate in thickness shear.

  Further, the crystal frame 20 and the base portion 22 are further joined by the low melting point glass LG disposed in the first step portion 223 of the base portion 22. That is, in the second embodiment, the electrical connection between the crystal frame 20 and the base portion 22 is performed by eutectic metal (see FIG. 11), and the hermetic bonding is performed by the low melting point glass LG. As a result, the quartz crystal vibrating portion 101 of the quartz frame 20 is sealed, and a cavity CT filled with nitrogen gas or in a vacuum state is formed. That is, the second crystal unit 100 of the second embodiment can prevent an increase in capacitance by using different materials for electrical bonding and airtight bonding.

  Further, in the second embodiment, the lid portion 21 and the crystal frame 20 are joined by the low melting point glass LG that is a joining material, but may be joined by eutectic metal as in the first embodiment, or the anode You may join by joining.

<Method for Manufacturing Second Crystal Resonator 200>
FIG. 15 is a flowchart showing a method for manufacturing the second crystal unit 200. In FIG. 15, the manufacturing step S21 of the lid portion 21, the manufacturing step S22 of the crystal frame 20, and the manufacturing step S23 of the base portion 22 can be performed separately and in parallel.

In step S21, the lid part 21 is manufactured. Step S21 includes steps S211 and S212.
In step S211, hundreds to thousands of second step portions 213 are formed on a crystal flat lid wafer having a uniform thickness by etching or machining. As a result, a second end face M2 is formed on the outer periphery of the second step portion 213. Please refer to FIG. 7 and FIG.

  In step S212, the low melting point glass LG is formed on the second end face M2 of the lid wafer by screen printing. Thereafter, the low-melting glass LG is temporarily cured, so that the low-melting glass LG is disposed on the second end face M2 of the lid wafer. Please refer to FIG.

In step S22, the crystal frame 20 is manufactured. Step S22 includes steps S221 and S222.
In step S221, the outer shape of the plurality of crystal frames 20 is formed by etching on a uniform crystal wafer. That is, the crystal vibrating part 101, the frame body 204, and the through opening 108 are formed. Refer to FIG. 8, FIG. 9 and FIG.

  In step S222, the first excitation electrode 102a, the second excitation electrode 102b, the first extraction electrode 203a, and the second extraction electrode 203b are formed on both surfaces of the quartz wafer by sputtering and etching. Please refer to FIG. 12 and FIG.

In step S23, the base portion 22 is manufactured. Step S23 includes steps S231 to S233.
In step S231, the first step surface 223 and the first end face M1 on the outer periphery of the first step portion 223 are formed by etching or machining on a crystal wafer having a uniform thickness. At the same time, through holes are formed on both sides of each base portion 22 in the X-axis direction so as to penetrate the base wafer. In addition, eutectic metal grooves for positioning the spherical eutectic metal EC are formed at the four corners of the base portion 22, respectively. Please refer to FIG. 10 and FIG.

  In step S232, a pair of mounting terminals 225a and 225b are formed on the first end surface M1 and the mounting surface M3 of the base portion 22 by sputtering and etching. Please refer to FIG.

  In step S233, the low melting point glass LG is formed on the first step portion 223 of the base wafer by screen printing. Please refer to FIG.

  In step S24, a plurality of spherical eutectic metals are placed in the eutectic metal grooves of the base wafer. Refer to FIG.

  In step S25, the lid wafer and the crystal wafer are bonded by the low melting point glass LG, and the crystal wafer and the base wafer are bonded by the eutectic metal EC and the low melting point glass LG. In other words, in the bonding of the quartz wafer and the base wafer, electrical bonding is performed using a eutectic metal, and hermetic bonding is performed using the low melting point glass LG. That is, the second crystal unit 200 can prevent an increase in capacitance by using different materials for electrical bonding and airtight bonding. Refer to FIG.

  Here, the lid wafer and the quartz wafer are bonded by the low melting point glass LG, but may be bonded by other eutectic metal or anodic bonding.

  In step S26, the bonded lid wafer, crystal wafer, and base wafer are individually cut. In the cutting step, the second crystal unit 200 is divided into individual pieces along the scribe line using a dicing apparatus using a laser or a dicing apparatus using a cutting blade. Thereby, hundreds to thousands of second crystal resonators 200 are manufactured. Please refer to FIGS.

  As described above, the optimal embodiment has been described in detail in the present specification. However, as will be apparent to those skilled in the art, the present invention can be implemented with various modifications and variations within the technical scope thereof. .

  In this specification, the base wafer, the crystal wafer, the lid wafer, and the like are bonded to each other by the low melting point glass, but a polyimide resin may be used instead of the low melting point glass. When a polyimide resin is used, screen printing may be used, or exposure may be performed after a photosensitive polyimide resin is applied to the entire surface.

  For example, in this specification, an AT-cut crystal frame has been described as an example, but the present invention is also applicable to a tuning-fork type crystal frame having a pair of vibrating arms.

  The present invention is also applied to an inverted mesa type crystal frame in which the crystal vibration part is formed thinner than the frame.

  Furthermore, the present invention can be applied to a piezoelectric oscillator in which an IC incorporating an oscillation circuit is accommodated in a cavity in addition to a crystal resonator.

DESCRIPTION OF SYMBOLS 10, 20 ... Crystal frame, 10W ... Crystal wafer 11, 21 ... Lid part, 11W ... Lid wafer 12, 22 ... Base part, 12W ... Base wafer 100, 200 ... Crystal vibrator 101 ... Crystal vibration part 102a ... First excitation electrode 102b ... 2nd excitation electrode 103a, 203a ... 1st extraction electrode, 103b, 203b ... 2nd extraction electrode 104, 204 ... Frame 105a, 105b ... Connection part 106a, 106b, 126a, 126b ... Castellation 108 ... Through-opening Part 109, 128 ... Eutectic metal groove part 111 ... Lid concave part 121 ... Base concave part 112 ... Metal film 123, 223 ... First step part 113, 213 ... Second step part 125a, 125b, 225a, 225b ... Mounting terminal CT… Cavity EC… Eutectic Genus M1 ... first end surface, M2 ... second end surface Me ... surface, Mi ... backside SL ... scribe line SP ... clearance

Claims (11)

A piezoelectric vibrating frame having a piezoelectric vibrating piece having a pair of excitation electrodes formed on both main surfaces, and a frame surrounding the piezoelectric vibrating piece and having a pair of extraction electrodes drawn from the excitation electrode on one main surface;
A first end surface joined to one main surface of the frame body of the piezoelectric vibration frame, a mounting surface opposite to the first end surface, and extending from the mounting surface to the first end surface. A first plate having a pair of mounting terminals to be joined and a first step portion formed inside the entire circumference of the first end surface and recessed from the first end surface;
A bonding material disposed at the first step portion of the first plate and bonding the frame and the first plate;
A piezoelectric device comprising: A pair of the extraction electrodes formed on the frame body of the piezoelectric vibration frame are formed apart from each other by a predetermined distance,
2. The piezoelectric device according to claim 1, wherein the pair of mounting terminals formed on the first end surface of the base portion are formed at a predetermined distance from each other.   3. The piezoelectric device according to claim 1, wherein the piezoelectric vibration frame and the first plate are bonded by both the bonding material and eutectic metal bonding or anodic bonding. The piezoelectric vibrating frame further includes a connecting portion that connects the piezoelectric vibrating piece and the frame, and a through opening between the piezoelectric vibrating piece and the frame.
The extraction electrode extracted from the excitation electrode formed on the other main surface of the piezoelectric vibrating piece is formed to extend to the one main surface of the frame through the connection portion and the through opening. The piezoelectric device according to any one of claims 1 to 3. The piezoelectric vibration frame is formed with a first castellation that is recessed from the outer periphery thereof,
The said extraction electrode withdraw | derived from the said excitation electrode formed in the other main surface of the said piezoelectric vibrating piece is extended and formed to the said one main surface of the said frame through the said 1st castellation. Item 4. The piezoelectric device according to any one of Items 3 to 3.   The piezoelectric device according to any one of claims 1 to 5, further comprising a second plate having a second end surface joined to the other main surface of the frame body of the piezoelectric vibration frame. A metal film is formed on the second end surface of the second plate,
The extraction electrode extracted from the excitation electrode formed on the other main surface of the piezoelectric vibrating piece is formed on the other main surface of the frame;
The piezoelectric device according to claim 6, wherein the metal film of the second plate and the extraction electrode formed on the other main surface of the piezoelectric vibration frame are bonded by eutectic metal bonding or anodic bonding. The first plate is formed with a second castellation that is recessed from its outer periphery,
The piezoelectric device according to any one of claims 1 to 7, wherein the mounting terminal is formed to extend from the mounting surface to the first end surface via the second castellation. The first plate has a first recess recessed from the first step;
The second plate has a second stepped portion recessed from the second end surface and a second recessed portion further recessed from the second stepped portion,
The piezoelectric device according to any one of claims 1 to 8, wherein the bonding material is disposed in the first step portion and the second step portion.   The piezoelectric device according to claim 1, wherein the bonding material is low-melting glass or polyimide resin. The piezoelectric device according to any one of claims 1 to 10, wherein the frame is formed thicker than a thickness of the piezoelectric vibrating piece.