Abstract:
Methods are provided for manufacturing piezoelectric vibrating devices that do not contain any unwanted gas or water vapor inside the devices. In an exemplary method, a base wafer is prepared including multiple package bases each having a first main surface and a second main surface. The base wafer also includes a pair of through-holes disposed between adjacent package bases of the base wafer. A piezoelectric vibrating piece is placed on each package base. A lid wafer is prepared that includes multiple package lids. A sealing material is applied to the base wafer or lid wafer in peripheral bands used for bonding the bases and lids together and defines respective interior cavities. The band of sealing material includes a communicating groove that communicates from the inner cavity to the first through-hole. The base wafer and lid wafer are subject to heat and compression to effect bonding. Meanwhile, the cavities are allowed to ventilate through the communicating grooves and through-holes to ensure that the cavities have a desired vacuum level or inert gas contents before completion of sealing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Japan Patent Application No. 2010-186785, filed on Aug. 24, 2010, in the Japan Patent Office, the disclosure of which is incorporated herein by reference in its entirety. 
     FIELD 
     This disclosure pertains to, inter alia, piezoelectric vibrating devices that, during their manufacture, automatically ventilate unwanted gas from inside their respective packages before the packages are hermetically sealed, and to methods for manufacturing such devices. 
     TECHNICAL BACKGROUND 
     A surface-mount type piezoelectric device is one in which a piezoelectric vibrating piece is mounted on an insulating package base made of a material such as alumina ceramic. A package lid is then sealed to the package base to enclose the piezoelectric vibrating piece. During manufacture of such a piezoelectric device, a layer of sealing material, such as a polymeric resin or low-melting-point glass (LMPG), is formed on a sealing surface formed either on the package base or on the package lid. Using resin for forming a sealing layer can cause problems, such as parametric fluctuations, because polymeric resins tend to release gas under the elevated temperatures required for curing the resin. Even if the sealing layer is formed of LMPG, entrapped bubbles in the LMPG can release gas, causing adverse effects to the piezoelectric vibrating piece inside the package. 
     Japan Patent Publication No. JP 2005-026974A discloses a method for releasing unwanted gas from inside the package. On the entire edge-surface of the package base made of a non-conductive material, a first layer of LMPG is applied for temporary hardening. Then, a layer of a second LMPG is applied over the first layer and temporarily hardened. The second LMPG is not applied to pre-designated regions of the surface of the second LMPG, particularly regions connected to inside the package. These regions provide escape routes for release of gas from the package before completion of package sealing. 
     The method disclosed in JP &#39;974 disadvantageously requires two or more applications of LMPG and respective temporary hardening steps, which is process-intensive. Also, if the second LMPG has low viscosity, then the second LMPG tends to spread, before it has temporarily hardened, to regions where LMPG is not wanted. Replacing the low-viscosity LMPG with a higher-viscosity LMPG poses difficulties in sealing, due to the problem of the LMPG not flowing to surrounding regions. Furthermore, the manufacturing methods discussed in JP &#39;974 require applying LMPG on each individual piezoelectric device, which is unsuitable for mass-production. 
     Therefore, there is a need for methods for manufacturing piezoelectric devices, as disclosed herein, that do not result in entrapment of unwanted gas or water vapor inside the package containing the piezoelectric device. There is also a need for piezoelectric vibrating devices that do not contain unwanted gas or water vapor. 
     SUMMARY 
     A first aspect of the invention is directed to methods for manufacturing a piezoelectric device. An exemplary embodiment of such a method comprises preparing a base wafer including multiple package bases each having a first main surface including respective external electrodes and a second main surface opposite the first main surface. The second main surface includes a respective peripheral sealing main surface. The base wafer also defines at least a pair of respective through-holes located between adjacent package bases, wherein each through-hole extends from the first main surface to the second main surface. Each package base when assembled with a package lid forms a respective package defining an interior cavity. A respective piezoelectric vibrating piece is attached to each package base. Each vibrating piece includes a respective pair of excitation electrodes. A lid wafer is prepared that includes multiple package lids. Each package lid has a first main surface and a second main surface opposite the first main surface. The second main surface includes a respective peripheral sealing surface. A sealing material is applied onto the peripheral sealing surfaces of the package bases or onto the peripheral sealing surfaces of the package lids. The sealing material is applied as a continuous band having a predetermined width and including a “communicating groove” allowing temporary pneumatic communication to and from the interior cavity via the through-hole. In a vacuum or inert-gas atmosphere, gaseous exchange is made to and from the cavities via the respective communicating grooves and through-holes while applying heat and compression. The heat and compression bonds the wafers together while allowing flow of sealing material into at least a portion of the communicating grooves sufficient to seal the cavities after the gaseous exchange. 
     The method can further comprise forming a metal film on respective interior surfaces of the through-holes, wherein the metal film connects together each excitation electrode with a respective external electrode. 
     The sealing material desirably is an adhesive comprising a glass that melts between 350° C. to 410° C. This material is termed “low-melting-point glass.” 
     After bonding the wafers together, the bonded wafers desirably are cut along pre-established scribe lines to release and separate the individual piezoelectric vibrating devices. The scribe lines are located so as to allow cutting across respective communicating grooves. 
     In some embodiments the communicating grooves expand in width from the respective interior cavities to the scribe lines. Each communicating groove can have at least a portion having a width that is in a range of 10% to 30% of the width of the band of sealing material. 
     The package base in some embodiments has a rectangular plan profile. A respective through-hole can be located on each corner of the rectangular profile. The interior cavity also has a rectangular shape with opposing short sides and opposing long sides. In these and other embodiments each communicating groove can extend from a respective long side of the rectangular cavity to the through-hole. 
     In other embodiments in which the package base has a rectangular plan profile with opposing short sides and opposing long sides, a respective through-hole can be located between adjacent short sides. The interior cavity also has a rectangular shape, wherein each communicating groove extends from a respective long side of the rectangular cavity to the through-hole. 
     In another method embodiment a base wafer is prepared including multiple package bases each having a first main surface including respective external electrodes and a second main surface opposite the first main surface. The second main surface includes a respective peripheral sealing surface. The base wafer also defines at least a pair of first respective through-holes located between adjacent package bases, wherein each first through-hole extends from the first main surface to the second main surface. Each package base when assembled with a piezoelectric frame and package lid forms a respective package defining an interior cavity. Also prepared is a piezoelectric wafer that includes multiple piezoelectric frames. Each piezoelectric frame includes a respective piezoelectric vibrating piece attached to and surrounded by an outer frame. Each vibrating piece has respective excitation electrodes, a first peripheral sealing surface, and a second peripheral sealing surface. The piezoelectric wafer defines at least a pair of respective second through-holes located between adjacent outer frames, wherein each second through-hole extends from the first peripheral sealing surface to the second peripheral sealing surface. Also prepared is a lid wafer that includes multiple package lids each having an outer main surface and an inner main surface. The inner main surface includes a peripheral sealing surface. The method also comprises applying a sealing material on at least one of the peripheral sealing surface of the inner main surface of each lid and the first peripheral sealing surface of each outer frame, and on at least one of the second peripheral sealing surface of each outer frame and the peripheral sealing surface of the second main surface of each base. The sealing material is applied as a continuous band having a predetermined width, and includes a communicating groove allowing temporary communication to and from the interior cavity via the first through-holes or second through-holes. In a vacuum or inert-gas atmosphere, gaseous exchange to and from the cavities is allowed to occur via the communicating groove and respective through-holes during application of heat and compression. The heat and compression bond the wafers together while allowing flow of sealing material into at least a portion of the communicating grooves sufficient to seal the cavities after the gaseous exchange. 
     According to another aspect, piezoelectric devices are provided. An exemplary embodiment of such a device comprises a package base including an inner main surface and an outer main surface, wherein the outer main surface includes external electrodes and the inner main surface comprises a peripheral bonding region. A respective edge-surface electrode is connected to each external electrode, and each edge-surface electrode is located on an outer edge of the package base and extends on the outer edge in the thickness dimension between the inner and outer main surfaces. The device also comprises a piezoelectric vibrating piece supported by the package base. The vibrating piece includes a respective excitation electrode connected to each edge-surface electrode. A package lid is bonded to the package base to form an interior cavity enclosing the piezoelectric vibrating piece. The package lid includes an inner main surface and an outer main surface, wherein the inner main surface comprises a peripheral bonding region. A sealing material is disposed as a band on the respective peripheral bonding regions of the package base and package lid to bond the package base and lid together. The bands of sealing material have a predetermined width in the peripheral bonding regions and define at least one communicating groove extending therein between the interior cavity and at least one of the first edge-surface electrodes. The communicating groove is at least partially filled with the sealing material to seal the interior cavity hermetically. 
     In some embodiments the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each corner thereof. In these embodiments the second edge-surface electrodes can be formed on respective corner castellations. In other embodiments in which the outer frame and package base each have a respective rectangular plan profile, the devices can include a respective castellation on each of two sides, wherein the second edge-surface electrodes are formed on respective edge castellations. 
     According to another embodiment, a piezoelectric device comprises a package base including an inner main surface and an outer main surface, wherein the outer main surface includes external electrodes and the inner main surface comprises a peripheral bonding region. A respective first edge-surface electrode is connected to each external electrode. Each first edge-surface electrode is located on an outer edge of the package base and extends on the outer edge in the thickness dimension between the inner and outer main surfaces. The devices include a piezoelectric frame including a piezoelectric vibrating piece surrounded by an outer frame. The vibrating piece has first and second main surfaces each including a respective peripheral bonding region. The peripheral bonding region of the first main surface is bonded to the peripheral bonding region of the package base. The devices also include a respective second edge-surface electrode connected to each excitation electrode, wherein each second edge-surface electrode is located on an outer edge of the outer frame and extends on the outer edge in the thickness dimension between the first and second main surfaces of the outer frame. Each device also includes a package lid including an inner main surface and an outer main surface. The inner main surface includes a peripheral bonding region that is bonded to the peripheral bonding region of the second main surface of the frame to form an interior cavity enclosing the piezoelectric vibrating piece. A first sealing material is disposed as a band having a predetermined width between the peripheral bonding region of the package lid and the peripheral bonding region of the second main surface of the outer frame. A second sealing material (which can be the same as the first sealing material, or different) is disposed as a band at a predetermined width between the peripheral bonding region of the package base and the peripheral bonding region of the first main surface of the outer frame so as to bond the package lid, piezoelectric frame, and package base together. The bands of sealing material have predetermined widths in the respective peripheral bonding regions and define at least one communicating groove extending therein between the interior cavity and at least one of the first edge-surface electrodes. The communicating groove is at least partially filled with the sealing material to seal the interior cavity hermetically. 
     In some embodiments the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each of two sides thereof. In these embodiments the second edge-surface electrodes can be formed on respective edge castellations. 
     According to the foregoing summary, piezoelectric devices and associated manufacturing methods are provided. The devices do not contain any unwanted gas or water vapor in their interior cavities. The subject methods are readily applied to mass-production of the devices. Also, the various embodiments of piezoelectric devices oscillate or vibrate at a specified frequency, as a result of eliminating unwanted gas or water vapor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a quartz-crystal vibrating device according to the first embodiment, before the package base and package lid have been bonded together. 
         FIG. 2  is an elevational cross-section, along the line A-A in  FIG. 1 , after bonding the package lid to the package base. 
         FIG. 3A  is a perspective, upside-down view of the package lid of the first embodiment, before bonding it to the package base. 
         FIG. 3B  is a perspective, upside-down view of the package lid of the first embodiment, showing one manner in which a communicating groove is filled during compression performed during bonding. 
         FIG. 3C  is a perspective, upside-down view of the package lid of the first embodiment, showing another manner in which a communicating groove is at least partially filled by sealing material during bonding. 
         FIG. 4  is a flow-chart of protocols and steps in an embodiment of a method for manufacturing a quartz-crystal vibrating device according to the first embodiment. 
         FIG. 5  is a plan view of a lid wafer of the first embodiment, before bonding. 
         FIG. 6  is a plan view of a base wafer of the first embodiment, before bonding. 
         FIG. 7  is a plan view of a lid wafer of the second embodiment, before bonding. 
         FIG. 8A  is a perspective, upside-down view of a package lid of the second embodiment, after applying a sealing material. 
         FIG. 8B  is a perspective, upside-down view of a package lid of the second embodiment, showing a manner in which the communicating groove is filled at least partially by sealing material during bonding. 
         FIG. 9A  is a perspective, upside-down view of a package lid of the third embodiment, after applying a sealing material. 
         FIG. 9B  is a perspective, upside-down view of a package lid of the fourth embodiment, after applying a sealing material. 
         FIG. 10A  is a perspective, upside-down view of a package lid of the fifth embodiment, after applying a sealing material. 
         FIG. 10B  is a perspective, upside-down view of a package lid of the sixth embodiment, after applying a sealing material. 
         FIG. 11  is an exploded perspective view of a quartz-crystal vibrating device according to a seventh embodiment, before the package base and lid have been bonded together. 
         FIG. 12A  is a perspective, upside-down view of a package lid of the seventh embodiment, after applying a sealing material. 
         FIG. 12B  is another perspective, upside-down view of a package lid of the seventh embodiment, showing a manner in which the communicating groove is filled at least partially by sealing material during bonding. 
         FIG. 12C  is another perspective, upside-down view of a package lid of the seventh embodiment, showing a manner in which the communicating groove is filled at least partially by sealing material during bonding. 
         FIG. 13  is a plan view of a base wafer as used in the seventh embodiment. 
         FIG. 14  is an exploded perspective view of a quartz-crystal vibrating device according to the eighth embodiment, before the package base and lid have been bonded together. 
         FIG. 15  is a plan view of a quartz-crystal wafer as used in the eighth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are described in detail below, with reference to the accompanying drawings. 
     In the described embodiments, an AT-cut quartz-crystal vibrating piece is used as an exemplary piezoelectric vibrating piece. An AT-cut quartz-crystal vibrating piece has a principal surface (in the YZ plane) that is tilted by 35° 15′ about the Y-axis of the crystal coordinate system (XYZ) in the direction of the Y-axis from the Z-axis around the X-axis. Thus, in the following description, new axes tilted with respect to the axial directions of the quartz-crystal vibrating piece are denoted as the X′-axis, Y′-axis, and Z′-axis, respectively. Regarding a height in the Y′-axis direction, a positive (+) direction is denoted as high and a negative (−) direction is denoted as low. 
     First Embodiment of Quartz-Crystal Vibrating Device 
     The overall configuration of this embodiment of a quartz-crystal vibrating device  100 A is described with reference to  FIGS. 1 ,  2 , and  3 A- 3 C.  FIG. 1  is an exploded perspective view of a quartz-crystal vibrating device  100  of this embodiment before the package base and lid have been bonded together.  FIG. 2  is an elevational section, along the line A-A in  FIG. 1 , after stacking the package lid  11 A on the package base  12 A.  FIG. 3A  is a perspective, upside-down view of the package lid  11 A before it is bonded to the package base  12 A.  FIGS. 3B and 3C  are similar perspective views of the package lid  11 A after it is bonded to the package base  12 A. 
     In this specification, a situation in which the package base and package lid have been placed in vertical alignment with each other without being compressed together is referred to as “stacked,” and a situation in which the package base and package lid have been compressed together with sealing material (and thus bonded together) is referred to as “bonded.” 
     The first embodiment of a quartz-crystal vibrating device  100 A shown in  FIG. 1  includes a package lid  11 A that defines a lid recess  111 . The device also includes a package base  12 A that defines a base recess  121 . A quartz-crystal vibrating piece  10  is mounted onto the base recess  121 . The lid recess  111  and base recess  121  are formed by sand-blasting or wet-etching. For example, whenever the base recess  121  is formed by sand-blasting, the conjunction  126  of the bottom surface M 3  and the side surface M 4  of the base recess  121  is sharp, substantially without any corner radius. However, whenever the base recess  121  is formed by etching, the conjunction  126  has a significant corner radius. In this specification, the conjunctions are indicated as being sharp. 
     The quartz-crystal vibrating piece  10  comprises the quartz-crystal piece  10 . A respective excitation electrode  102   a ,  102   b  is disposed substantially centrally on each main surface of the quartz-crystal piece  19 , wherein the main surfaces face each other across the thickness dimension of the quartz-crystal piece  10 . A respective excitation electrode  102   a  is connected to the extraction electrode  103   a  and extends toward the −Z′-axis corner of the quartz-crystal piece  101  on the +X′-axis side. Similarly, a respective excitation electrode  102   b  is connected to the extraction electrode  103   a  and extends toward the +Z′-axis corner of the quartz-crystal piece  101  on the −X′-axis side. The quartz-crystal vibrating piece  10  is bonded to the package base  12 A, which is fabricated from a piezoelectric body such as glass or quartz-crystal. Bonding is performed using electrically conductive adhesive  13  ( FIG. 2 ). 
     The package base  12 A comprises a peripheral sealing surface M 2  on the upward-facing main surface (+Y′-side surface) surrounding the base recess  121 . On the package base  12 A are respective base castellations  122   a ,  122   b  on the −Z′-axis edge and on the +Z′-axis edge. On the lower main surface of the package base  12 A are external electrodes  125   a ,  125   b  formed in the +Z′-axis region and in the −Z′-axis region. The lower main surface is termed the vibrating device mounting surface. In each base castellation  122   a ,  122   b  is a respective base-edge electrode  123   a ,  123   b  connected to the respective external electrode  125   a ,  125   b . Thus, the base-edge electrodes  123   a ,  123   b  connect the respective base castellations  122   a ,  122   b  to the respective external electrodes  125   a ,  125   b . Also, connecting electrodes  124   a ,  124   b  on the peripheral sealing surface M 2  of the package base  12 A and are also connected to the respective base edge-surface electrodes  123   a ,  123   b.    
     Turning to  FIG. 2 , an electrically conductive adhesive  13  is applied onto each connecting electrode  124   a ,  124   b . The electrically conductive adhesive  13  connects the extraction electrodes  103   a ,  103   a  on the quartz-crystal vibrating piece  10  to the respective connecting electrodes  124   a ,  124   b . Thus, the quartz-crystal vibrating piece  10  is mounted onto the peripheral sealing surface M 2  of the package base  12 A, which achieves connection of the excitation electrodes  102   a ,  102   b  on the quartz-crystal vibrating piece  10  to the respective external electrodes  125   a  via the respective extraction electrodes  103   a ,  103   b , and achieves connection of the electrodes  124   a ,  124   b  to the respective base-edge electrodes  123   a ,  123   b . Whenever an alternating voltage (voltage that alternates between positive and negative values of a selected voltage) is applied across the external electrodes  125   a ,  125   b , the quartz-crystal vibrating device  10  exhibits thickness-shear vibration. 
     This embodiment of a quartz-crystal vibrating device  100 A also comprises a package lid  11 A, which is bonded to the peripheral sealing surface M 2  on the package base  12 A using a sealing material such as low-melting-point glass LG. Bonding the package lid  11 A to the package base  12 A forms an interior cavity CT in which the quartz-crystal vibrating piece  10  is mounted. The cavity CT is filled with an inert gas or is evacuated. 
     The low-melting-point glass LG is a lead-free, vanadium-based glass having an adhesive component that melts at 350° C. to 400° C. Vanadium-based glass can be formulated as a paste mixed with binder and solvent, and bonds to various materials by melting and solidifying. The melting point of vanadium-based glass is lower than the melting point of the package lid  11 A or the melting point of the package base  12 A since the package lid and base are fabricated of piezoelectric material or glass. Vanadium-based glass forms a highly reliable air-tight seal and resists water and humidity. Low-melting-point glass (LMP glass) forms a highly reliable air-tight seal and resists water and humidity from entering into the cavity CT. Since the coefficient of thermal expansion of LMP glass can be controlled effectively by controlling its glass structure, LMP glass can be bonded to various materials having different respective coefficients of thermal expansion, such as ceramics, glass, semiconductor material, and metal. 
     In  FIG. 3A , the lid recess  111  is drawn upside-down (facing upward), to provide clarity. The package lid  11 A is cubic-shaped, with an exemplary length L 1  in the Z′-axis direction of approximately 3,200 μm, an exemplary width W 1  in the X′-axis direction of approximately 2,500 μm, and an exemplary height H 1  in the Y′-axis direction of approximately 180 μm. Although not shown, the package base  12 A can have the same dimensions as the package lid  11 A. 
     The package lid  11 A has a peripheral sealing M 1  surrounding the lid recess  111 . The peripheral sealing surface M 1  is bonded to the peripheral sealing surface M 2  of the package base  12 A. The width W 3  of the peripheral sealing surface M 1  is approximately 400 μm. On the peripheral sealing M 1  of the package lid  11 A, a layer of low-melting-point glass LG is applied; this layer has a thickness D of 10 μm to 15 μm. 
     As the low-melting-point glass LG is applied to the peripheral sealing surface M 1  of the package lid  11 A, a “communication groove”  112  is also formed. The communication groove  112  includes a first groove portion  112   a , a second groove portion  112   b , and a third groove portion  112   c . One end of the first groove portion  112   a  (extending in the +X′-axis direction) opens into the lid recess  111 , and the other end (extending in the −X′-axis direction) is connected to the second groove portion  112   b  (extending in the +Z′-axis direction). One end of the third groove portion  112   c  (extending in the −X′-axis direction) is connected to the second end of the second groove portion  112   b . The second end of the third groove portion  112   c  extends toward the base castellation  122   a  so as to communicate with the base castellation whenever the package lid  11 A and package base  12 A are stacked together (see  FIGS. 1 and 2 ). 
     The width W 5  of each of the first groove portion  112   a , the second groove portion  112   b , and the third groove portion  112   c  is in the range of 10% to 30% of the width W 3  of the peripheral sealing M 1 . I.e., the width W 5  is in the range of 40 μm to 120 μm. In the first embodiment, further details are described below under the assumption that W 5 =100 μm. 
     The length W 4  of the first groove portion  112   a  in the X′-axis direction is approximately 300 μm. Therefore, on the second groove portion  112   b  (wherein W 5 =100 μm) the low-melting-point glass LG is applied on the +X′-axis side at a width of 200 μm, and on the −X′-axis side at a width of 100 μm. Since the first groove portion  112   a  is situated at substantially the center-line of the lid recess  111  in the Z′-axis direction, the length L 2  of the second groove portion  112   b  in the Z′-axis direction is approximately 1,600 μm. The length W 2  of the third groove portion  112   c  in the X′-axis direction is in the range of 800 μm to 1,000 μm. 
     As indicated by the lines BL in  FIG. 1 , whenever the package lid  11 A and package base  12 A are stacked together, the third groove portion  112   c  extends toward the base castellation  122   a . Also, as shown in  FIG. 2 , whenever the package base  12 A and package lid  11 A are stacked together, the third groove portion  112   c  is disposed on top of the base castellation  122   a.    
     Consequently, whenever the package base  12 A and package lid  11 A are stacked together prior to bonding, the cavity CT is in communication with the exterior environment via the base castellation  122   a  and the communicating groove  112 . Hence, whenever the stacked-together package base  12 A and package lid  11 A is placed inside a vacuum reflow chamber, gas formed between particles of the low-melting-glass is released to the environment outside the cavity CT. Also, whenever the package base  12 A and package lid  11 A, as stacked together, are placed inside a chamber filled with an inert gas, the inert gas flows via the communicating groove  112  to inside the cavity CT. 
     After these gaseous exchanges through the communicating groove  112  are completed, the package base  12 A and package lid  11 A are bonded together by continued heating of the low-melting-point glass LG and compressing the package lid  11 A and package base  12 A together. During this compression, low-melting-point glass LG situated in the adjacent communicating groove  112  migrates into the communicating groove  112  and seals it, leaving the cavity CT with the desired vacuum or inert gas inside. 
     There are various ways in which to seal the communicating groove  112 , depending upon the manner in which the package lid and base are compressed together. In  FIG. 3B , some of the low-melting-point glass LG in the vicinity of the second groove portion  112   b  is pressed, thereby hermetically sealing the communicating groove  112 . In this instance, even if the package base  12 A and package lid  11 A are bonded together, the groove portion  112 A connected to the cavity CT and the groove portion  112 B connected to the base castellation  122   a  remain, indicating the residual presence of the communicating groove  112 . 
     In  FIG. 3C , some of the low-melting-point glass LG in the vicinity of the first groove portion  112   a  is compressed, thereby hermetically sealing the communicating groove  112 . In this instance, even if the package base  12 A and package lid  11 A are bonded together, the groove portion  112 ′ remains, indicating the residual presence of the communicating groove  112 . Although not shown in the drawings, the two regions of low-melting-point glass LG indicated in  FIGS. 3B and 3C  may be filled at the same time. Also, the first groove portion  112   a  and second groove portion  112   b  may be compressed entirely together, which would eliminate all the groove portions. 
     In  FIGS. 3B and 3C , regions of low-melting-point glass LG around the third groove portion  112   c  are not likely to be compressed. Due to the presence of the base castellation  122   a , the low-melting-point glass LG applied near the third groove portion unit  112   c  is not likely to be affected by pressure even when the package lid  11 A and package base  12 A are compressed together. Also, even when strong compression is applied to the low-melting-point glass LG, it tends merely to flow into the base castellation  122   a  rather than seal the communicating groove  112 . 
     In the first embodiment, the low-melting-point glass LG is applied in a peripheral zone around the package lid  11 A. Alternatively, the low-melting-point glass can be applied to the peripheral sealing surface  112  formed on the package base  12 A instead of to the package lid  11 A. Alternatively, the low-melting-point glass can be applied to the peripheral surfaces on both the package lid  11 A and the package base  12 A. 
     Method for Manufacturing First Embodiment of Quartz-Crystal Vibrating Device 
       FIG. 4  is a flow-chart showing an embodiment of a method for manufacturing the first embodiment of a quartz-crystal vibrating device  100 A. In  FIG. 4 , the protocol S 10  is directed to manufacture of the quartz-crystal vibrating piece  10 , the protocol S 11  is directed to manufacturing the package lid  11 A, and the protocol S 12  is directed to manufacturing the package base  12 A. These protocols can be performed separately or in parallel.  FIG. 5  is a plan view of the lid wafer  11 W used in this embodiment.  FIG. 6  is a plan view of the base wafer  12 W used in this embodiment. 
     In protocol S 10 , the quartz-crystal vibrating piece  10  is manufactured. Protocol S 10  comprises steps S 101  and S 102 . In step S 101 , a layer of chromium (Cr) is formed, followed by formation of an overlying layer of gold (Au), on both main surfaces of a quartz-crystal wafer (not shown) by sputtering or vacuum-deposition. Then, a photoresist is applied uniformly over the surface of the metal layer. Using an exposure tool (not shown), the profile outlines of the quartz-crystal vibrating pieces  10  are lithographically exposed onto the main surfaces of the quartz-crystal wafer. 
     After removing unneeded regions of the gold and chromium layers, second layers of chromium (Cr) and gold (Au) are formed. Then, a photoresist is applied uniformly on both surfaces of the quartz-crystal wafer. Using an exposure tool (not shown), the profile outlines of the quartz-crystal vibrating pieces  10  are lithographically exposed onto both surfaces of the quartz-crystal wafer. Unneeded regions of the gold layer and chromium layer are removed again, and third layers of chromium (Cr) and gold (Au) are formed. Then, a photoresist is applied uniformly on both main surfaces of the quartz-crystal wafer to form the patterns of electrodes on both main surfaces of the quartz-crystal wafer. Then, the gold and chromium layers are etched to form the excitation electrodes  102   a ,  102   b  and extraction electrodes  103   a ,  103   b  on the quartz-crystal wafer. 
     In step S 102 , individual quartz-crystal vibrating pieces  10  are cut from the quartz-crystal wafer to form multiple separate pieces each having excitation electrodes  102   a ,  102   b  and extraction electrodes  103   a ,  103   b.    
     In protocol S 11 , the package lid  11 A is manufactured. Protocol S 11  comprises steps S 111  and S 112 . In step S 111 , as shown in  FIG. 5 , several hundreds to several thousands of lid recesses  111  are formed on the lid wafer  11 W, which is a circular, uniformly planar plate of quartz-crystal material. On the lid wafer  11 W, lid recesses  111  are formed by etching or mechanical processing. Each lid recess  111  is surrounded by a respective peripheral sealing surface M 1 . 
     In step S 112 , as shown in  FIG. 5 , a low-melting-point glass LG is printed on the peripheral sealing surfaces M 1  on the lid wafer  11 W by screen-printing. The low-melting-point glass LG is applied in a manner that also forms the communicating groove  112  that provides communication of the lid recess  111  to the external environment (ventilated via the base through-hole BH 1  in  FIG. 6 ). Then, the low-melting-point glass LG on the peripheral sealing surfaces M 1  is preliminarily cured. 
     In protocol S 12 , package bases  12 A are manufactured, Protocol S 12  comprises steps S 121  and S 122 . In step S 121 , as shown in  FIG. 6 , several hundreds to several thousands of base recesses  121  are formed on a base wafer  12 W, which is a circular, uniformly planar plate of quartz-crystal material. On the base wafer  12 W, the base recesses  121  are formed by etching or mechanical processing. Each base recess  121  is surrounded by a peripheral sealing surface M 2 . Respective rounded-rectangular through-holes BH 1  are also formed (between longitudinal sides of adjacent package bases) on the package base  12 A in the Z′-axis directions. The through-holes extend depthwise through the thickness of the base wafer  12 W. Later, when the base through-holes BH 1  are cut through in half, they form respective base castellations  122   a ,  122   b  (refer to  FIG. 1 ). 
     In step S 122 , a layer of chromium (Cr) is formed, followed by formation of an overlying layer of gold (Au), on both main surfaces of the base wafer  12 W by sputtering or vacuum-deposition. After selected regions in this metal bilayer are etched, connecting electrodes  124   a ,  124   b  are formed on peripheral sealing surfaces M 2 , as shown in  FIG. 6 . At the same time, the external electrodes  125   a ,  125   b  are formed on the base wafer  12 W, and the base edge-surface electrodes  123   a ,  123   b  are formed on the inner surfaces of the base through-holes BH 1  (refer to  FIG. 1 ). 
     In step S 13 , the quartz-crystal vibrating pieces  10 , manufactured in protocol S 10 , are mounted onto the peripheral sealing surfaces M 2  on the package bases  12 A using electrically conductive adhesive  13 . Here, the quartz-crystal vibrating piece  10  is mounted onto the peripheral sealing surface M 2  of the package base  12 A ( FIG. 2 ), so as to align the extraction electrodes  103   a ,  103   b  on the quartz-crystal vibrating pieces  10  with respective connecting electrodes  124   a ,  124   b  formed on the peripheral sealing surface M 2  of the package bases  12 A. 
     In step S 14 , the lid wafer  11 W and base wafer  12 W are stacked together by co-aligning them. The lid wafer  11 W in  FIG. 5  includes a respective orientation flat OF formed on an outer edge thereof, and the base wafer  12 W includes a respective orientation flat OF formed on an outer edge thereof. Using the orientation flats OF as alignment references, the lid wafer  11 W and the base wafer  12 W are precisely aligned together when the wafers are stacked. When stacked, the lid recesses  111  and base recesses  121  form respective cavities CT. Each cavity CT communicates to the external environment via respective base through-holes BH 1  and communicating grooves  112 . As a stack, the wafers are heated in an evacuated chamber or in a chamber filled with inert gas, at a temperature in the range of 350° C. to 400° C. The wafers must be adequately heated. Placing wafers inside the chamber that are not well-heated initially prevents the low-melting-point glass LG from reaching its melting point. If the wafers are placed in a vacuum-reflow chamber, the gas inside the cavity CT is ventilated via the communicating groove  112  to the external environment in the chamber. Alternatively, if placed in a chamber filled with inert gas, the inert gas may enter the cavities CT via the communicating groove  112 . 
     In step S 15 , the lid wafer  11 W and the base wafer  12 W are compressed against each other to bond the lid wafer  11 W to the base wafer  12 W. When the wafers are placed inside a vacuum-reflow chamber or a chamber filled with an inert gas, the low-melting-point glass LG is heated to a temperature in the range of 350° C. to 400° C., in which the low-melting-point glass LG reaches its the melting temperature. At this point, whenever the lid wafer  11 W and base wafer  12 W are compressed against each other, at least some of the low-melting-point glass enters the communicating groove  112  to seal it (refer to  FIGS. 3B and 3C ). Thus, the cavities CT are formed that are either evacuated or filled with inert gas. After cooling the stacked wafers to room temperature, the low-melting-point glass LG solidifies and bonds together the lid wafer  11 W and base wafer  12 W. 
     In step S 16 , the bonded lid wafer  11 W and base wafer  12 W is cut into individual pieces. The quartz-crystal vibrating devices  100 A are cut into individual pieces using a dicing unit such as laser beam or dicing saw. The cuts are made by cutting along predetermined scribe lines SL, denoted by dot-dash lines in  FIGS. 5 and 6 . In this first embodiment, the desired width of the laser or cutting blade is in the range of 50 to 200 μm. Thus, several hundreds to several thousands of quartz-crystal vibrating devices  100 A according to the first embodiment are made. 
     Second Embodiment of Quartz-Crystal Vibrating Device 
     In the second embodiment, the package lid  11 B comprises a communicating groove  212  having a different shape than the communicating groove  112  in the first embodiment. The following descriptions of the package lid  11 B are made with reference to  FIGS. 7 and 8 .  FIG. 7  is a plan view of the lid wafer  21 W before bonding.  FIG. 8A  is an exploded perspective view of the package lid  11 B before bonding, and  FIG. 8B  is an exploded perspective view of the package lid  11 B after bonding. In this embodiment, components that are similar to corresponding components in the first embodiment have the same reference numerals. 
     Turning first to  FIG. 7 , the lid wafer  21 W defines communicating grooves  212 , each including a first groove portion  212   a , a second groove portion  212   b , and a third groove portion  212   c  located on the peripheral sealing surface M 1  of the respective lid. One end of the first groove portion  212   a  extends in the X′-axis direction and opens in the respective lid recess  111 , while the other end is connected to the second groove portion  212   b , which extends in the Z′-axis direction. The third groove portion  212   c  extends in the X′-axis direction and is connected to the other end of the second groove portion  212   b . The width W 5  of the first groove portion  212   a , the second groove portion  212   b , and the third groove portion  212   c  is in the range of 10% to 30% of the width W 3  of the peripheral sealing surface M 1 ; i.e., W 5 =40 μm to 120 μm. In this second embodiment, details are described below with the width W 5  assumed to be 100 μm, On the lid wafer  21 W, the distance W 6  between adjacent package lids  111  in the X′-axis directions is a sum: W 6 =2(W 3 )+W 5 . 
     The length W 7  of the first groove portion  212   a  in the X′-axis direction is also a sum: W 7 =W 3 +W 5 , which is approximately 500 μm. Also, since the first groove portion  212   a  makes its connection substantially along the center-line of the package lid  111  in the Z′-axis direction, the length L 2  of the second groove portion  212   b  in the Z′-axis direction is approximately 1,600 μm. The length W 8  of the third groove portion  212   c  in the X′-axis direction is approximately 900 μm to 1,100 μm. Whenever the package lid  11 B and package base  12 A are stacked together, the third groove portion  212   c  extends toward the region of the base castellation  122   a  ( FIG. 1 ). Therefore, whenever the lid wafer  21 W and base wafer  12 W ( FIG. 6 ) are stacked together, the cavity CT is in communication with the external environment via the base through-hole BH 1  ( FIG. 6 ) and the communicating groove  212 . 
     In this second embodiment, the width of the laser or blade used for cutting the bonded lid wafer  21 W and base wafer  12 W ( FIG. 6 ) is approximately 100 μm. To prevent clogging of the dicing apparatus, it is preferred that the scribe lines SL (indicated by dot-dash lines) be formed along the second groove portion  212   b  of the communicating groove  212 . 
     The package lid  11 B before bonding is as indicated in  FIG. 8A . This means that the second groove portion  212   b  is not disposed, and the first groove portion  212   a , the second groove portion  212   b , and the third groove portion  212   c  are formed on the peripheral sealing surface M 1  of the package lid  11 B extending in the X′-axis direction. 
     To seal the cavity CT hermetically after stacking the lid wafer  21 W and base  12 W, the first groove portion  212   a  connected to the cavity CT (lid recess  111  in  FIG. 8 ) needs to be sealed, as shown in  FIG. 8B . When the low-melting-point glass LG is heated and the lid wafer  11 W and base wafer  12 W are being compressed together, the low-melting-point glass LG surrounding the first groove portion  212   a  spreads and closes off the first groove portion  212   a  so as to seal it hermetically. In this case, even if the package base  12 A and package lid  11 A are bonded together, the groove portion  212   a ′ remains, indicating the prior presence of the communicating groove  212  before the low-melting-point glass LG was compressed. 
     In the third groove portion  212   c , which partially covers the base through-hole BH 1 , the low-melting-glass LG surrounding the third groove portion  212   c  will not likely compressed. 
     Manufacturing the Second Embodiment of a Quartz-Crystal Vibrating Device 
     The second embodiment of a quartz-crystal vibrating device is manufactured by a method that is substantially similar to the flow-chart of  FIG. 4  depicting the method for manufacturing the first embodiment of a quartz-crystal vibrating device  100 A. In step S 15  pertaining to the separation of individual quartz-crystal vibrating pieces from one another, the lid wafer  21  is cut along the second groove portion  212   b  on the communicating groove  212  extending along the Z′-axis direction. 
     The following third to sixth embodiments have respective package lids having different communicating grooves. When discussing the package lid being compressed against the package base, the filling of the communicating groove with compressed low-melting-point glass is not described or shown in the respective drawings. 
     Third Embodiment of Crystal Vibrating Devices 
       FIG. 9A  is a perspective view of a package lid  11 C after forming the communicating groove  312  but before performing compression. On the peripheral sealing surface M 1  of the package lid  11 C, low-melting-point glass LG is applied as a sealing material. As applied, the low-melting-glass LG defines a communicating groove  312  used for temporarily communicating the lid recess  111  to the external environment. The communicating groove  312  has a serpentine pattern that provides multiple folds in the X′-axis direction. When bonding the package lid  11 C to the package base  12 A the low-melting-point glass LG in the vicinity of the communicating groove  312  is squeezed so as to seal the communicating groove  312  hermetically. Since the total length of the communicating groove  312  is compressed into the serpentine pattern, and thus longer than in the first and second embodiments, the length over which the communicating groove  312  can be sealed is correspondingly extended. This allows, for example, the cavity CT to be sealed in a vacuum. 
     Fourth Embodiment of Crystal Vibrating Device 
       FIG. 9B  is a perspective view of the package lid  11 D of the fourth embodiment before bonding but after forming the communicating groove  412 . 
     The communicating groove  412 , defined in the as-applied low-melting-glass LG, has a longitudinally extended zigzag pattern, in which the groove is folded multiple times in the Z′-axis direction. During bonding the package lid  11 D and package base  12 A together, compression causes the low-melting-point glass LG in the vicinity of the communicating groove  412  to be squeezed in a manner that closes off the communicating groove  412  and hermetically seals it. Since the length of the communicating groove  412  is extended compared to the first and second embodiments, the sealing area of the communicating groove  412  is correspondingly extended. 
     Fifth Embodiment of Crystal Vibrating Device 
       FIG. 10A  is a perspective view of the package lid  11 E of the fifth embodiment after forming the communicating groove  512 , but before bonding the package lid to the package base. On the peripheral sealing surface M 1  of the package lid  11 E, low-melting-glass LG is applied as a sealing material. The communicating groove  512  comprises a first groove portion  512   a  and a third groove portion  512   c , both extending in the X′-axis direction, and a second groove portion  512   b . The second groove portion  512   b  is connected to the first groove portion  512   a  and the third groove portion  512   c  and extends in the Z′-axis direction. The first groove portion  512   a  is configured to connect, while widening smoothly, from its opening into the lid recess  111  to the second groove portion  512   b . The narrower opening of the first groove portion  512   a  into the lid recess  111  is approximately 50 μm, and the wider connection of the first groove portion  512   a  to the second groove portion  512   b  is approximately 200 μm. Thus, one end of the first groove portion  512   a  is connected to the lid recess  111 . The third groove portion  512   c  connects the second groove portion  512   b  to the base through-hole BH 1  ( FIG. 6 ). 
     In the configuration shown in  FIG. 10A , since the end of the first groove portion  512   a  opening into the lid recess  111  is narrower, this end of the communicating groove  512   a  can be easily sealed when the package lid  11 E is being bonded to the package base  12 A. Also, since the first groove portion  512   a  expands in width from the lid recess  111  outward in a substantially linear manner, pneumatic communication via the groove  512  is assured. 
     Sixth Embodiment of Crystal Vibrating Device 
       FIG. 10B  is a perspective view of the package lid  11 F of the sixth embodiment after forming the communicating groove  512  but before bonding. On the peripheral sealing surface M 1  of the package lid  11 F, low-melting-point glass LG is applied as a sealing material. The communicating groove  612  comprises a first groove portion  612   a  and a third groove portion  612   c , both extending in the X′-axis direction, and a second groove portion  612   b . The second groove portion  612   b  extends in the Z′-axis direction. The first groove portion  612   a  is configured to connect, while widening in a stepwise manner, from its opening into the lid recess  111  to the second groove portion  612   b . The narrower opening of the first groove portion  612   aa  into the lid recess  111  is approximately 50 μm, and the wider connection of the first groove portion  612   a  to the second groove portion  612   b  is approximately 200 μm. 
     Seventh Embodiment of Crystal Vibrating Device 
     The configuration of the seventh embodiment of a quartz-crystal vibrating device  100 G is described with references to  FIGS. 11 and 12 .  FIG. 11  is an exploded perspective view of the embodiment  100 G before being bonded together.  FIG. 12A  is a perspective view of the package lid  11 G before it is bonded to the package base, and  FIGS. 12B and 12C  are upside-down perspective views of the package lid  11 G in the seventh embodiment after the sealant has spread out by application of heat and pressure. In this embodiment, components that are similar to corresponding components in the first embodiment have the same reference numerals. 
     Turning first to  FIG. 11 , the seventh embodiment of a quartz-crystal vibrating device  100 G comprises a package lid  11 G defining a lid recess  111 , a package base  12 G defining a base recess  121 , and a quartz-crystal vibrating piece  10 ′ mounted inside the base recess  121 . Extraction electrodes  103   a  and  103   b ′ are formed on the −Y′ surface of the quartz-crystal vibrating piece  10 ′. The quartz-crystal vibrating piece  10 ′ is bonded to the package base  12 G, which is fabricated of a material such as a piezoelectric material (e.g., quartz-crystal) or glass, using an electrically conductive adhesive  13 . Each of the four corners of the package base includes a respective base castellation  722   a - 722   d . On the lower main surface (i.e., the mounting surface of the quartz-crystal vibrating device) of the package base  12 G are a pair of excitation electrodes  725   a ,  725   b  formed on both Z′-axis edges of the device. Opposing corners of the package base  12 G include respective base castellations  722   a ,  722   b , on which respective base edge-surface electrodes  723   a ,  723   b  are formed. One end of each edge-surface electrode is connected to a respective external electrode  725   a . The other two opposing corners of the package base also include respective base castellations  722   c ,  722   d . Each of these base castellations  722   c ,  722   d  includes a respective edge-surface electrode  723   c ,  723   d  that is connected to a respective external electrode  725   a ,  725   b . On the peripheral sealing surface M 2  of the package base  12 G are connecting electrodes  724   a ,  724   b , which are connected to the other ends of the respective base edge-surface electrodes  723   a - 723   d.    
     The connecting electrode  724   b  is situated on the peripheral sealing surface M 2  of the package base  121  just outboard of the base recess  121 . The connecting electrode  724   b  extends on the peripheral sealing surface M 2  in the −Z′-axis direction to the same side of the peripheral sealing surface M 2  as the connecting electrode  724   a . Alternatively, the connecting electrode  724   b  can extend (in the −Z′-axis direction) across the bottom surface M 3  of the package base  121  to the same side of the peripheral sealing surface M 2  on which the connecting electrode  724   a  is located. 
     Similar to the first embodiment, when mounting the quartz-crystal vibrating piece  10 ′ onto the peripheral sealing surface M 2  of the package base, the excitation electrodes  102   a ,  102   b  on the quartz-crystal vibrating piece  10 ′ are connected to the respective connecting electrodes  724   a ,  724   b  on the package base  12 G. Hence, whenever an alternating voltage (voltage that alternates between the positive and negative of a particular value) is applied across the external electrodes  125   a ,  125   b , the quartz-crystal vibrating device  10 ′ exhibits thickness-shear vibration. 
     The package lid  11 G is described with reference to  FIGS. 12A-12C . In these figures, the lid recess  111  is drawn facing upward to provide a better understanding. As shown in  FIG. 12A , the package lid  11 G comprises a peripheral sealing surface M 1  that surrounds the lid recess  111 . The peripheral sealing surface M 1  is bonded to the peripheral sealing surface M 2  of the package base  12 G. 
     Low-melting-point glass LG is applied to the peripheral sealing surface M 1  of the package lid  11 G in a manner that forms a communicating groove  712 . The communicating groove  712  includes a first groove portion  712   a  and a second groove portion  712   b . One end of the first groove portion  712   a  extends in the X′-axis direction to the lid recess  111 , while the other end is connected to the second groove portion  712   b . The second groove portion  712   b  extends in the Z′-axis direction. Here, the dimensions of the first groove portion  712   a  and the second groove portion  712   b  are as described for the respective first groove portion  112   a  and second groove portion  112   b  in the first embodiment. Whenever the package lid  11 G and package base  12 G are bonded together, the second groove portion  712   b  extends to the base castellation  722   a  (see base line BL in  FIG. 11 ). 
     Whenever the package lid  11 G and package base  12 G are stacked together for bonding, the cavity CT is connected temporarily to the external environment via the base castellation  722   a  and the communicating groove  712 . This temporary communication is sufficient to achieve the desired gaseous exchange. After the cavity has been appropriately ventilated (with an inert gas or evacuated), the communicating groove  712  is hermetically sealed as the cavity CT itself is sealed hermetically. During bonding, application of heat and pressure to the package lid  11 G and package base  12 G squeezes the low-melting-point glass LG in the vicinity of the communicating groove  712 , which compresses it and seals the communicating groove  712  with the low-melting-point glass. 
       FIG. 12B  shows a situation, after compression, in which some of the low-melting-point glass LG in the vicinity of the second groove portion  712   b  has been squeezed. Even after bonding this package lid  11 G and package base  12 G together, the first groove portion  712   a  and a part of the second groove portion  712   b  remain open to the cavity CT, while another part of the second groove portion  712   b  remains open to the base castellation  722   a . These vestigial openings indicate the residual existence of the communicating groove  712  before the low-melting-point glass LG had been compressed. 
     In  FIG. 12C , some of the low-melting-point glass LG surrounding the first groove unit  712   a  has been compressed, thereby sealing the communicating groove  712 . Even after bonding this package lid  11 G to the package base  12 G, the groove portion  712 ′ remains, indicating the residual presence of the communicating groove  712  before compression of the low-melting-point glass LG. Although not indicated in the drawings, two areas of low-melting-point glass LG indicated in  FIGS. 12B and 12C  may be compressed at the same time. Also, the entire first groove portion  712   a  and second groove portion  712   b  may be compressed. 
     The seventh embodiment of a quartz-crystal vibrating device can be manufactured by a method depicted by a flow-chart that is substantially similar to the flow-chart of  FIG. 4 . However, during manufacture of the seventh embodiment, the shape of the extraction electrode  103   b ′ on the quartz-crystal vibrating piece  10 ′ in the protocol S 10  is different. Also, the shape of the communicating groove formed in the low-melting-point glass LG in step S 112  is different. Also, the protocol S 12  for manufacturing the package base  12 G is different from the first embodiment. In the following description, the protocol S 12  for manufacturing the base wafer  72 W is explained with reference to  FIG. 13 .  FIG. 13  is a plan view of the base wafer in the seventh embodiment. 
     In step S 121 , as shown in  FIG. 13 , the base recesses  121  are formed on the base wafer. At the same time, respective base through-holes BH 2  are formed on the four corners of the package base  12 G. Each through-hole BH 2  is a circular cut-hole that extends through the base wafer  72 W depthwise. When the bonded wafer is being cut along cut lines, these round through-holes BH 2  are become four respective quarter-round sections, which become the castellations  722   a - 722   d  (see  FIG. 11 ). 
     In step S 122 , the external electrodes  725   a ,  725   b  ( FIG. 11 ) are formed on the lower main surface of the base wafer  72 W, as indicated in  FIG. 13 . Also, in the base through-holes BH 2  are formed respective base edge-surface electrodes  723   a ,  723   b , which are connected to the respective external electrode  725   a . Also formed are the base edge-surface electrodes  723   c ,  723   d , which are connected to the external electrode  725   b , ( FIG. 11 ). On the peripheral sealing surface M 2  are formed the connecting electrode  724   a  (connected to the base edge-surface electrodes  723   a ,  723   b ) and the connecting electrode  724   b  (connected to the base edge-surface electrodes  723   c ,  723   d.    
     Eighth Embodiment of Crystal Vibrating Device 
     The general configuration of this embodiment of a quartz-crystal vibrating device  100 H is described with reference to  FIG. 14 .  FIG. 14  is an exploded perspective view of the eighth embodiment  100 H before bonding the pieces together. In this embodiment, components that are similar to corresponding components in the first embodiment have the same reference numerals. 
     As shown in  FIG. 14 , the vibrating device  100 H comprises a quartz-crystal frame  20  that is sandwiched between the package lid  11 A and the package base  12 H. When the package lid  11 A and the package base  12 H are bonded to respective peripheral sealing surfaces of the quartz-crystal frame  20 , the package base  12 H and the quartz-crystal frame  20  form a cavity CT ( FIG. 2 ). In the eighth embodiment, the package lid  11 A is bonded to the quartz-crystal frame  20  using low-melting-point glass LG, and the package base  12 H is bonded to the quartz-crystal frame  20  using low-melting-point glass LG. 
     In this embodiment the connecting electrodes  124   a ,  124   b  ( FIG. 1 ) are not formed on the package base  12 H, which is different from the package base  12 A used in the first embodiment. 
     The quartz-crystal frame  20  is fabricated from an AT-cut quartz-crystal material having an upper main surface Me facing the package lid  11 H and a lower main surface Mi facing the package base  12 H. The quartz-crystal frame  20  comprises a vibrating portion  201  (including the excitation electrodes  202   a ,  202   b ) and an outer frame  205  that surrounds the vibrating portion  201 . Also, a respective joining portion  204   a  and  204   b  extends between an edge of the vibrating portion  201  and the outer frame  205 . The joining portions  204   a ,  204   b  extend from the vibrating portion  201  to each edge of the outer frame  205  in the Z′-axis directions. This leaves two L-shaped voids  208  situated between the vibrating portion  201  and the outer frame  205 . On both edges of the quartz-crystal frame  20  in the Z′-axis directions, respective castellations  206   a ,  206   b  are formed. These castellations were originally formed as rounded-rectangular quartz-crystal through-holes CH ( FIG. 15 ). On each castellation  206   a ,  206   b  is a respective side-surface electrode  207   a ,  207   b.    
     On the upper main surface Me of the joining portion  204   a , an extraction electrode  203   a  is formed. The extraction electrode connects from the respective excitation electrode  202   a  to the respective edge-surface electrode  207   a  on the respective castellation  206   a . On the lower main surface Mi of the joining portion  204   b , an extraction electrode  203   b  is formed. The extraction electrode  203   b  connects from the respective excitation electrode  202   b  to the respective edge-surface electrode  207   b  on the respective castellation  206   b.    
     When the stacked upper main surface Me on the crystal frame  20  is bonded to the package lid  11 A, and the lower main surface Mi on the crystal frame  20  is bonded to the package base  20 H, the communicating groove  112  extends to the quartz-crystal castellation  206   a . Hence, when the package lid  11 A is stacked onto the quartz-crystal frame  20  for bonding, the cavity CT is in temporary pneumatic communication with the external environment via the base castellation  122   a , the quartz-crystal castellation  206   a , and the communicating groove  112 . 
     During bonding, but after ventilating the cavity, the applied low-melting-point glass LG is heated while the package lid  11 A and quartz-crystal frame  20  are being compressed together, which bonds the quartz-crystal frame  20  and package lid  11 A together. During compression of the low-melting-point glass LG in the vicinity of the communicating groove  112 , the communicating groove  112  becomes hermetically sealed after having been evacuated or filled with an inert gas as specified during the previous gaseous exchange. 
     The excitation electrodes  202   a ,  202   b  are connected to respective external electrodes  125   a ,  125   b  (formed on the lower main surface (mounting surface) of the vibrating device  100 H) via respective extraction electrodes  203   a ,  203   b , edge-surface electrodes  207   a ,  207   b , and base edge-surface electrodes  123   a ,  123   b.    
     In this eighth embodiment, after the package base  12 H and the quartz-crystal frame  20  have been bonded together using the low-melting-point glass LG, the package lid  11 A is bonded to the quartz-crystal frame  20 . Alternatively, the package base  12 H, the quartz-crystal frame  20 , and the package lid  11 A can be bonded together at the same time. Although low-melting-point glass LG was applied on the package lid  11 A, the low-melting-point glass alternatively can be formed on the peripheral sealing surface Me of the quartz-crystal frame  20 . 
     In this embodiment, although the package base  12 H and the quartz-crystal frame  20  are bonded together using the low-melting-point glass LG, the package base  12 H and quartz-crystal frame  20  can alternatively be bonded together by siloxane bonding or by anodic bonding, instead of using low-melting-point glass LG. 
     During manufacture of the eighth embodiment  100 H, the package lid  11 A is manufactured by the following protocol S 11  described in the first embodiment. The package base  12 H is manufactured according to the protocol S 12  described in the first embodiment. However, this embodiment still includes the steps of forming each electrode, forming the pair of external electrodes  125   a ,  125   b , and forming the base edge-surface electrodes  123   a ,  123   b.    
     The method for manufacturing the quartz-crystal frame  20  is described using  FIG. 15  as a reference.  FIG. 15  is a plan view of the quartz-crystal wafer  20 W of this embodiment. First, a profile outline of the quartz-crystal frame  20  is formed on a planar quartz-crystal wafer  20 W by etching. During this step the quartz-crystal vibrating portion  201 , the outer frame  205 , and the pair of voids  208  are formed, and the rounded, rectangular through-holes CH are formed on each quartz-crystal frame  20  in the Z′-axis directions. Each half of a quartz-crystal through-hole CH forms a respective castellation  206   a ,  206   b  ( FIG. 14 ). 
     On both surfaces of the quartz-crystal wafer  20 W and on the surface of the through-holes CH, a foundation layer of chromium (Cr) is formed, followed by an overlying layer of gold (Au), are formed by sputtering or vacuum-deposition. 
     Then, a photoresist is applied uniformly on the entire surface of the metal film. Using an exposure tool (not shown), the outline pattern of the excitation electrodes  202   a ,  202   b , the extraction electrodes  203   a ,  203   b , and the quartz-crystal side-surface electrodes  207   a ,  207   b  are exposed onto the quartz-crystal wafer  20 W. Afterward, regions of the metal layer denuded by the photoresist are etched. As shown in  FIG. 14 , the excitation electrodes  202   a ,  202   b  and the extraction electrodes  203   a ,  203   b  are formed on the quartz-crystal wafer  20 W, and the edge-surface electrodes  207   a ,  207   b  are formed on the inside surfaces of the through-holes CH. 
     INDUSTRIAL APPLICABILITY 
     Representative embodiments have been described in detail above. As evident to those skilled in the art, the present invention may be changed or modified in various ways within the technical scope of the invention. For example, as an alternative to AT-cut quartz-crystal vibrating pieces, the present invention may be directed to the manufacture of tuning-fork type vibrating pieces. In this specification, although the various embodiments have been described in the context of quartz-crystal vibrating pieces, it will be understood that the embodiments can be applied with equal facility to piezoelectric materials such as lithium tantalite and lithium niobate. Furthermore, the present disclosure can be applied to piezoelectric oscillators that also include an IC configured as an oscillating circuit mounted inside the package on the package base.