Patent Publication Number: US-7719171-B2

Title: Method of fabricating hermetic terminal and hermetic terminal, method of fabricating piezoelectric oscillator and piezoelectric oscillator, oscillator, electronic appliance, and radio clock

Description:
This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. JP2007-219234 filed on Aug. 27, 2007, the entire content of which is hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method of fabricating a hermetic terminal and a hermetic terminal, a method of fabricating a piezoelectric oscillator and a piezoelectric oscillator, an oscillator, an electronic appliance, and a radio clock. 
   2. Description of the Related Art 
   In recent years, mobile telephones and portable information terminal devices employ a piezoelectric oscillator using quartz crystal as a time source, a timing source of control signals, and a reference signal source. As this type of piezoelectric oscillator, various ones are offered. As one of them, a cylinder package piezoelectric oscillator formed in a cylindrical shape is known. 
   As shown in  FIG. 30 , a piezoelectric oscillator  70  is configured to have a tuning fork piezoelectric vibrating piece  71 , a case  72  in a cylindrical shape with a bottom in which the piezoelectric vibrating piece  71  is accommodated, and a hermetic terminal  73  that hermetically seals the piezoelectric vibrating piece  71  inside the case  72 . 
   The hermetic terminal  73  is configured of an annular ring  74  formed of a metal material, two leads  75  arranged as they penetrate through the ring  74  and are individually joined to two mount electrodes  71   a  of the piezoelectric vibrating piece  71 , and a filler  76  that fixes the leads  75  to the ring  74  in one piece in an insulating state and hermetically seals the inside of the case  72 . 
   The two leads  75  each have an inner lead portion  75   a  that is the portion extended inside the case  72  and have an outer lead portion  75   b  that is the portion extended outside the case  72 . Then, the outer lead portion  75   b  functions as an external connecting terminal. 
   In addition, the case  72  is pressed, fitted, and fixed to the outer side of the ring  74 . Since the case  72  is press fitted under a vacuum atmosphere, the space surrounding the piezoelectric vibrating piece  71  inside the case  72  is hermetically sealed in the vacuum state. 
   In the piezoelectric oscillator  70  thus configured, a predetermined voltage is applied as drive voltage to each of the outer lead portions  75   b  of the two leads  75 , and then current is carried from the inner lead portion  75   a  to the piezoelectric vibrating piece  71  through the mount electrode  71   a . Thus, the piezoelectric vibrating piece  71  oscillates at a predetermined frequency. 
   This type of piezoelectric oscillator is mounted on various electronic appliances. However, since these electronic appliances are being reduced in size year after year, also in the piezoelectric oscillator, further size reduction is demanded. In order to reduce the size of the piezoelectric oscillator, it is effective to reduce the outer diameter of the ring. To this end, it is necessary to reduce the diameters of two leads. However, in the case in which the leads are made narrower than the current form, the stiffness is decreased, and then it is likely to deform the leads in the process of fabrication. Particularly, the outer lead portions that are longer than the inner lead portions tend to become deformed. When the outer lead portions become deformed, they cannot maintain themselves in the state of being parallel with each other. Thus, the quality is degraded, and the oscillator cannot be used as a product. Consequently, it is likely to cause a reduction in yields. 
   In addition, in the process of fabrication, the outer lead portions are entangled with the outer lead portions of another hermetic terminal, which might temporarily stop the production line. Also in this point, it is likely to cause a reduction in yields. Particularly, the more size reduction is aimed, the more the problems might occur noticeably. On this account, in the fabricating method under present conditions, it is difficult to fabricate a piezoelectric oscillator of high yields and high quality which can be further reduced in size. Particularly, it is difficult to fabricate a hermetic terminal configuring a piezoelectric oscillator. 
   Then, a piezoelectric oscillator is provided which has a hermetic terminal with a single lead, not two leads (see JP-A-2002-43886). This hermetic terminal has a projecting piece formed in one piece with a ring, and the projecting piece serves as the role of the inner lead portion before. In other words, the lead and the projecting piece are electrically connected to a piezoelectric vibrating piece. As described above, since the projecting piece formed in one piece with the ring is allowed to function as the inner lead portion, two leads, which are required before, can be reduced to a single lead. 
   On this account, even though the outer diameter of the ring is reduced, it is unnecessary to reduce the diameter of the lead as compared with the case of using two leads, a reduction in stiffness can be prevented, and the deformation of the lead can be prevented. In addition to this, since a single lead is provided, leads are unlikely to become entangled with each other in the process of fabrication, and thus the hermetic terminal can be reduced in size, and the piezoelectric oscillator can be reduced in size. 
   In addition, in the hermetic terminal which supports the piezoelectric vibrating piece inside the case including the hermetic terminal  73  of the piezoelectric oscillator  70  shown in  FIG. 30  and the hermetic terminal described in the Patent Reference 1, some of them are configured in which a piezoelectric vibrating piece is arranged closer to the center inside the case, in order to reliably prevent such a problem that the piezoelectric vibrating piece is contacted to the case, one of the end parts of the inner lead portion supporting the piezoelectric vibrating piece is flattened to form a stair portion, and the stair portion holds the piezoelectric vibrating piece. 
   In the manufacture of the piezoelectric oscillator including the hermetic terminal having this stair portion, generally, after the flattening process for forming the stair portion, plating is applied to the hermetic terminal to plate the lead, and then, the hermetic terminal is set in a holding member such as a unit frame. Then, the hermetic terminal is transferred to the subsequent process step in every holding member, and the set hermetic terminal is used to complete the piezoelectric oscillator. 
   Here, the reason why plating is performed after the flattening step is that in the case in which the inner lead portion is flattened after plated, a plating might be removed from the formed stair portion by being flattened. In addition, the reason why the holding member is set after plated is that it is difficult to plate the hermetic terminal in the state in which the hermetic terminal is set on the holding member. 
   However, the methods before still have the following problems. 
   In the fabricating method in which the flattening process is performed for forming the stair portion, the hermetic terminal is plated, and then the hermetic terminal is set on the holding member, it is extremely difficult to align and set the hermetic terminal in setting the hermetic terminals on the holding member. In other words, in setting the hermetic terminal on the holding member, the stair portion is already formed on the inner lead portion by flattening the inner lead portion. Thus, in setting the hermetic terminal on the holding member, it is necessary to align the direction (orientation) of the stair portion by a demand from the subsequent process step so that the hermetic terminal can be directed upward, for example. However, since the hermetic terminal is a tiny component and the size of the stair portion is also small, it is extremely difficult to set the hermetic terminal on the holding member as the direction (orientation) of the stair portion is aligned in one direction particularly in the case in which the premise is automation of high efficiency (at high speed), which is a cause that hinders automation. In addition, the difficulty in setting the hermetic terminals as they are aligned is noticeable in the case in which the lead is a single lead particularly as the hermetic terminal described in Patent Reference 1 because of low instability when a hermetic terminal intermediate is laid down. 
   In addition, in the hermetic terminal described in Patent Reference 1, it is necessary to form the projecting piece in one piece with the ring. In addition to this, it is necessary to form the projecting piece on a part of the ring formed annular. However, this process is not easily to perform, which takes a lot of efforts and time. Particularly, since it is necessary to bend the projecting piece while the ring is prevented from being deformed in bending the projecting piece, productivity is not excellent. Therefore, actually, it is necessary to produce a large amount of hermetic terminals a day, but the hermetic terminal is not suited for such mass production. 
   BRIEF SUMMARY 
   The invention is made in the light of circumstances. An object is to provide a method of fabricating a hermetic terminal and a hermetic terminal which particularly facilitate flattening an inner lead portion and setting the terminal on a holding member, a method of fabricating a piezoelectric oscillator and a piezoelectric oscillator which prevent excitation electrodes provided on two surfaces of a piezoelectric vibrating piece from being short-circuited to each other as well as allow size reduction in addition to high reliability of the connecting position of the piezoelectric vibrating piece, and an oscillator, an electronic appliance, and a radio clock which include the piezoelectric oscillator. 
   In order to solve the problems, a method of fabricating a hermetic terminal according to the invention is a method of fabricating a hermetic terminal having an annular ring, a lead arranged to penetrate through the ring in which one end side thereof is an inner lead portion electrically connected to a piezoelectric vibrating piece and the other end side thereof is an outer lead portion electrically connected to outside as the ring is between them, and a filler fixing the lead to the ring, wherein the hermetic terminal seals the piezoelectric vibrating piece inside a case, the method including the steps of: applying a plating process to a hermetic terminal intermediate having the lead fixed in the ring with the filler to plate the ring and the lead; setting the hermetic terminal intermediate after subjected to the plating process on a holding member; and flattening an end part of an inner lead portion in the lead to form a stair portion in the hermetic terminal intermediate set on the holding member. 
   According to the method of fabricating a hermetic terminal, the hermetic terminal intermediate, in which the filler and the lead are incorporated in the ring and they are fired to fix the lead with the filler, is subjected to the plating process, and set on the holding member, and then the end part of the inner lead portion is flattened to form the stair portion. Therefore, the hermetic terminal intermediate can be readily set on the holding member. In other words, in setting the hermetic terminal intermediate on the holding member, since the stair portion is not formed on the hermetic terminal intermediate, it is of course unnecessary to align the direction (orientation) of the stair portion, and thus it is unnecessary to align the direction of the stair portion. In addition, after that, the end part of the inner lead portion of the hermetic terminal intermediate set on the holding member is flattened to from the stair portion. Therefore, the direction (orientation) of the stair portion can be easily aligned to the holding member. Furthermore, since the holding member can stabilize the attitude of the hermetic terminal intermediate, the flattening process for the inner lead portion itself can be facilitated. 
   In addition, in the method of fabricating the hermetic terminal, preferably, the lead is a single lead. 
   As discussed above, in the case in which the lead is a single lead, the hermetic terminal intermediate is unstable when it is laid down, and it is difficult to align and set the hermetic terminal in the case in which the stair portion is formed in the previous step. As described above, the hermetic terminal intermediate is set on the holding member, and then flatted, which facilitates setting the hermetic terminal intermediate on the holding member and flattening the inner lead portion regardless of the stability of the hermetic terminal intermediate when it is laid down. 
   In addition, since the lead is a single lead, even though the outer diameter of the ring is made smaller, it is unnecessary to reduce the diameter of the lead as compared with the case of two leads, and it is unlikely that leads are not entangled with each other in the process of fabrication. Therefore, the hermetic terminal can be reduced in size, and the piezoelectric oscillator using the same can be reduced in size. 
   In addition, in the method of fabricating the hermetic terminal, preferably, in the flattening step, a die having a film made of Ti—Cr coated at least on a flattening surface is used as a flattening tool. 
   Since the film made of Ti—Cr is hard and excellent in durability, such a hard film is provided on the flattening surface, whereby the flattening surface can be formed into a smooth surface with no projections and depressions as well as can maintain the smoothness for a long time. Therefore, also in the case in which the inner lead portion after plated is flattened with this flattening surface, no damage occurs in the plated surface of the stair portion formed by being flattened because the flattening surface is smooth. Thus, such a problem can be prevented that a plating is removed and transferred to the flattening surface side. 
   In addition, in the method of fabricating the hermetic terminal, preferably, the holding member is formed of a long product in a belt shape, and in the setting step, the hermetic terminal intermediate is continuously arranged in the longitudinal direction of the holding member in a state in which the end part of the inner lead portion of the hermetic terminal intermediate is arranged outside the holding member. 
   With this configuration, the end part of the held hermetic terminal intermediate to be the inner lead portion can be flattened while the holding member is being moved in the length direction. Thus, the flattening step can be automated highly efficiently (at high speed). 
   A hermetic terminal according to the invention is fabricated according to the fabricating method described above. 
   According to the hermetic terminal, as discussed above, processing can be facilitated such as flattening the inner lead portion and setting the hermetic terminal intermediate on the holding member, and thus the mass production of the hermetic terminal, the improvement of yields, and the cost reduction are allowed. 
   A method of fabricating a piezoelectric oscillator according to the invention is a method of fabricating a piezoelectric oscillator including: a piezoelectric vibrating piece, a case having an opening for accommodating the piezoelectric vibrating piece therein; and a hermetic terminal having an annular ring, a lead arranged to penetrate through the ring in which one end side thereof is an inner lead portion electrically connected to a piezoelectric vibrating piece and the other end side thereof is an outer lead portion electrically connected to outside as the ring is between them, and a filler fixing the lead to the ring, wherein the hermetic terminal seals the piezoelectric vibrating piece inside a case, wherein the hermetic terminal is fabricated by the fabricating method above. 
   In addition, a piezoelectric oscillator according to the invention is fabricated according to the fabricating method described above. 
   According to the method of fabricating the piezoelectric oscillator and the piezoelectric oscillator obtained by the method, particularly as to the manufacture of the hermetic terminal, as discussed above, since flattening the inner lead portion and setting the hermetic terminal intermediate on the holding member are facilitated, the overall manufacture can be facilitated, and the mass production, the improvement of yields, and the cost reduction are allowed. 
   In addition, in the piezoelectric oscillator, preferably, the case is configured with conductivity; the ring has: a press fitting portion press fitted into an opening of the case, and a reducing portion extended from the press fitting portion with a clearance to the inner side surface of the case with conductivity, the lead is a single lead, the piezoelectric vibrating piece in a plate shape is arranged in the case and has an excitation electrode on each of two surfaces thereof, wherein one of the excitation electrodes is connected to the inner lead portion of the lead through a bump, whereby the piezoelectric vibrating piece is supported by the inner lead portion, and the other one on the opposite side of the excitation electrode is wire bonded to the outer side surface of the reducing portion of the ring. 
   According to the piezoelectric oscillator, since one of the excitation electrodes of the piezoelectric vibrating piece is connected to the inner lead portion through the bump, and the other one is wire bonded to the reducing portion of the ring, the size can be reduced while the excitation electrodes are prevented from being short-circuited to each other as well as the piezoelectric oscillator can be readily fabricated with excellent yields. 
   In addition, since the lead is a single lead, even though the outer diameter of the ring is made smaller, it is unnecessary to reduce the diameter of the lead as compared with the case of two leads, and it is unlikely that leads are entangled with each other in the process of fabrication. Therefore, the hermetic terminal can be reduced in size, and thus the piezoelectric oscillator itself can be reduced in size. 
   In addition, an oscillator according to the invention includes the piezoelectric oscillator connected to an integrated circuit as an oscillating element. 
   In addition, an electronic appliance according to the invention includes the piezoelectric oscillator. 
   In addition, a radio clock according to the invention includes the piezoelectric oscillator electrically connected to a filter part. 
   In accordance with the oscillator, the electronic appliance, and the radio clock according to the invention, since they include the piezoelectric oscillator that allows easy manufacture, the improvement of mass production and yields, and the cost reduction, the costs of the oscillator, the electronic appliance, and the radio clock themselves can be curtailed. 
   In accordance with the method of fabricating a hermetic terminal according to the invention, since processing can be made easier by facilitating flattening the inner lead portion and setting the hermetic terminal intermediate on the holding member, the mass production, the improvement of yields, and the cost reduction are allowed. 
   In accordance with the hermetic terminal according to the invention, processing can be facilitated such as flattening the inner lead portion and setting the hermetic terminal intermediate on the holding member, and thus the mass production, the improvement of yields, and the cost reduction are allowed. 
   In accordance with the method of fabricating a piezoelectric oscillator according to the invention, and the piezoelectric oscillator according to the invention obtained by the method, particularly as to the manufacture of the hermetic terminal, as discussed above, since flattening the inner lead portion and setting the hermetic terminal intermediate on the holding member can be facilitated, the overall manufacture can be facilitated, and the mass production, the improvement of yields, and the cost reduction are allowed. 
   In accordance with the oscillator, the electronic appliance, and the radio clock according to the invention, since they include the piezoelectric oscillator that allows easy manufacture, the improvement of mass production and yields, and the cost reduction, the costs of the oscillator, the electronic appliance, and the radio clock themselves can be curtailed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a top view depicting the piezoelectric oscillator according to a first embodiment of the invention; 
       FIG. 2  shows a cross section in a cutting line A-A in  FIG. 1  depicting the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 3  shows a cross section in a cutting line B-B in  FIG. 1  depicting the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 4  shows a flow chart depicting the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 5  shows an illustration depicting a piezoelectric oscillator producing process step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 6A to 6D  each show an illustration depicting a ring forming step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 7  shows an illustration depicting a ring loading step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 8  shows an illustration depicting a filler inserting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 9  shows an illustration depicting a lead inserting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 10  shows an illustration depicting a filler firing step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 11  shows a schematic diagram depicting a hermetic terminal intermediate prepared in a hermetic terminal fabricating process step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 12  shows an illustration depicting a plating step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 13A and 13B  each show a schematic diagram depicting holding members in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 14A and 14B  each show an illustration depicting a setting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 15A and 15B  each show an illustration depicting a flattening step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 16A ,  16 B and  16 C each show an illustration depicting a flattening step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 17  shows an illustration depicting a shaping step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 18  shows an illustration depicting a bump forming step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 19  shows an illustration depicting a holding member cutting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 20A and 20B  each show an illustration depicting a first mounting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIGS. 21A and 21B  each show an illustration depicting a second mounting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 22  shows an illustration depicting a fine tuning step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 23  shows an illustration depicting a press fitting step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention 
       FIG. 24  shows an illustration depicting a separating step in the fabrication process steps of the piezoelectric oscillator according to the first embodiment of the invention; 
       FIG. 25  shows a side view depicting a piezoelectric oscillator according to a second embodiment of the invention; 
       FIG. 26  shows a front view depicting the piezoelectric oscillator according to the second embodiment of the invention; 
       FIG. 27  shows a schematic diagram depicting an oscillator according to a third embodiment of the invention; 
       FIG. 28  shows a block diagram depicting an electronic appliance according to a fourth embodiment of the invention; 
       FIG. 29  shows a block diagram depicting a radio clock according to a fifth embodiment of the invention; and 
       FIG. 30  shows a block diagram schematically depicting a piezoelectric oscillator before. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
     FIGS. 1 to 3  each show a diagram depicting a piezoelectric oscillator according to a first embodiment of the invention.  FIG. 1  shows a cross sectional side view depicting the piezoelectric oscillator according to the embodiment overall,  FIG. 2  shows a cross section depicting line A-A shown in  FIG. 1 , and  FIG. 3  shows a cross section depicting line B-B shown in  FIG. 1 . 
   As shown in  FIGS. 1 to 3 , a piezoelectric oscillator  1  according to the embodiment is a cylinder package piezoelectric oscillator, which is configured to include a piezoelectric vibrating piece  2 , a case  3  in a nearly cylindrical shape with a bottom which accommodates the piezoelectric vibrating piece  2  therein and covers therearound, and a hermetic terminal  4  which hermetically seals an opening  3   a  of the case  3 . In the embodiment, the piezoelectric vibrating piece  2  is a tuning fork vibrating piece, which is formed of a quartz crystal piece  2   a  in a nearly plate shape having a pair of oscillating arm portions  5  and  6  adjacently arranged in parallel with each other, and a base portion  7  fixing the base end side of the oscillating arm portions  5  and  6  in one piece. In addition, on each of two surfaces of the quartz crystal piece  2   a , a conductive film such as chromium (Cr), nickel (Ni), aluminum (Al) or titanium (Ti) is formed in a predetermined pattern to provide a first excitation electrode  8 , and a second excitation electrode  9 . The first excitation electrode  8  and the second excitation electrode  9  are electrically isolated to each other and patterned. 
   Then, voltage is applied to each of the first excitation electrode  8  and the second excitation electrode  9  to oscillate them at a predetermined resonance frequency in the direction of bringing the oscillating arm portions  5  and  6  closer to each other or separating them from each other. In addition, on the tip end side of the oscillating arm portions  5  and  6 , at least one of the first excitation electrode  8  and the second excitation electrode  9  has a fine tuning part  10  and a coarse tuning part  11  formed of a chromium (Cr) film. Since the fine tuning part  10  and the coarse tuning part  11  have some cuts by applying a laser beam, whereby the oscillating arm portions  5  and  6  are set to a predetermined resonance frequency. 
   The hermetic terminal  4  is an embodiment of the hermetic terminal according to the invention, which is configured to include a ring  12  in a nearly cylindrical shape press fitted into the opening  3   a  of the case  3 , a lead  13  inserted into the ring  12 , a filler  14  filled between the ring  12  and the lead  13  inside the ring  12  for hermetically sealing the ring  12 . The filler  14  is formed of a material having insulating properties. In the embodiment, the filler  14  is formed of a glass ring made of borosilicate glass having a through hole  14   a . In other words, the filler  14  is inserted into the ring  12 , and fired in the state in which the lead  13  is inserted into the through hole  14   a , whereby the filler  14  insulates the ring  12  from the lead  13  as well as hermetically seals in the case  3 . 
   The lead  13  is arranged to be coaxial with a center axis C 3  of the case  3  and a center axis C 12  of the ring  12 , having an inner lead portion  15  extended from the ring  12  to the inner side of the case  3 , and a first outer lead portion  16  extended from the ring  12  to the outer side of the case  3 , and the lead  13  is formed of a bar-shaped member, described later. On the tip end side of the inner lead portion  15 , a bump connecting portion  15   a  is formed, which is formed of a stair portion in a nearly flat surface. In a flattening step, described later, the bump connecting portion  15   a  is formed into the stair portion in which a part (one side) of the lead  13  is flattened to near the center axis C 3  to have a nearly flat surface. Then, to the bump connecting portion (stair portion)  15   a , the first excitation electrode  8  of the piezoelectric vibrating piece  2  is connected through the bump in the base portion  7 , whereby the first excitation electrode  8  and the lead  13  are electrically connected to each other, and the piezoelectric vibrating piece  2  is supported by the inner lead portion  15  of the lead  13  in an open-sided shape. 
   The ring  12  is configured to have a press fitting portion  12   a  in a nearly cylindrical shape, and a reducing portion  12   b  extended from the press fitting portion  12   a  into the case  3 . The outer diameter of the press fitting portion  12   a  is formed nearly equal to the inner diameter of the case  3 , and the press fitting portion  12   a  is press fitted into the case  3 . In addition, the reducing portion  12   b  is formed to have a diameter smaller than that of the press fitting portion  12   a , and arranged to have a clearance  12   d  between it and the inner side surface of the case  3 . On a part of the outer side surface  12   c  of the reducing portion  12   b , two step portions  12   e  and  12   f  in a nearly flat surface are formed. The two step portions  12   e  and  12   f  are formed nearly symmetrically to the center axis C 12  of the ring  12 , and nearly in parallel with two surfaces on which the first excitation electrode  8  and the second excitation electrode  9  of the piezoelectric vibrating piece  2  are formed. 
   In addition, the ring  12  is formed of a conductive material. Preferably, this conductive material is a material having a thermal expansion coefficient almost similar to that of glass to form the filler  14 . For example, an iron-nickel-cobalt alloy or an iron-nickel alloy is preferably used. Then, the step portion  12   e  on the bump connecting portion (stair portion)  15   a  side in the two step portions  12   e  and  12   f  of the ring  12  is wire bonded to the second excitation electrode  9  of the piezoelectric vibrating piece  2  with a wire  17 , and they are electrically connected to each other. In addition, in the embodiment, two wires  17  are provided. 
   The case  3  is formed of a conductive material in a nearly cylindrical shape with a bottom, having the opening  3   a  on one end side, and the bottom part  3   b  on the other end side. Into the opening  3   a  of the case  3 , the ring  12  of the hermetic terminal  4  is press fitted, whereby the inside of the case  3  is hermetically sealed in the vacuum state. 
   In addition, the bottom part  3   b  of the case  3  is formed with a second outer lead portion  18  projecting outside. In this configuration, the piezoelectric oscillator  1  according to the embodiment can conduct to the first excitation electrode  8  of the piezoelectric vibrating piece  2  from outside the case  3  through the lead  13  with the first outer lead portion  16  as well as to the second excitation electrode  9  of the piezoelectric vibrating piece  2  from outside through the case  3 , the ring  12  and the wire  17  with the second outer lead portion  18 . In addition, gold plating (not shown) is partially applied to the portion in which the wire  17  is joined to the step portion  12   e  of the ring  12  of the hermetic terminal  4  and the bump connecting portion  15   a  of the inner lead portion  15 , which allows excellent conductivity. This gold plating is deposited in a film thickness of about a few angstroms in the step portion  12   e  and the bump connecting portion  15   a.    
   Next, a method of fabricating the piezoelectric oscillator  1  will be described. 
     FIG. 4  shows a flow chart depicting the fabrication process steps of the piezoelectric oscillator  1  according to the embodiment, and  FIGS. 5 to 24  each show an illustration depicting the individual fabrication process steps. The fabrication process steps of the piezoelectric oscillator  1  according to the embodiment are roughly divided into a piezoelectric vibrating piece producing process step S 10  in which the piezoelectric vibrating piece is produced, a hermetic terminal fabricating process step S 20  in which the hermetic terminal  4  is fabricated, and an assembly process step S 40  in which the piezoelectric vibrating piece  2 , the hermetic terminal  4 , and the case  3  are assembled. Hereinafter, the individual steps will be described in detail. 
   In the piezoelectric vibrating piece producing process step S 10 , first, a Lumbered rough stone quartz crystal is sliced to prepare a wafer having a predetermined thickness, and the wafer is polished to a certain thickness. Then, the outer shape of the quartz crystal piece  2   a  is patterned and etched on the wafer by photolithography, whereby a plurality of the quartz crystal pieces  2   a  (see  FIGS. 1 and 2 ) can be prepared from the wafer. Subsequently, on each of the prepared quartz crystal pieces  2   a , metal films are deposited for the first excitation electrode  8 , the second excitation electrode  9 , the fine tuning part  10 , and the coarse tuning part  11 . Then, for each of the quartz crystal pieces  2   a , a laser beam is applied to the coarse tuning part  11  to partially evaporate the metal film forming the coarse tuning part  11  to change the weight, whereby the resonance frequency of the quartz crystal piece  2   a  is coarsely tuned, and then the piezoelectric vibrating piece  2  is completed. In addition, fine tuning in which the resonance frequency of the quartz crystal piece  2   a  is tuned more highly accurately is performed after assembled with the hermetic terminal  4 . Then, as shown in  FIG. 5 , a plurality of the piezoelectric vibrating pieces  2  thus prepared is arranged on a dedicated palette  30 , and carried to the assembly process step S 40 , described later. 
   Next, the hermetic terminal fabricating process step S 20 , which is an embodiment of the method of fabricating a hermetic terminal according to the invention, will be described. In the hermetic terminal fabricating process step S 20 , first, the ring  12  is prepared as a ring forming step S 21 . In other words, as shown in  FIG. 6A , a lance process is applied to a conductive plate member  31  such as an iron-nickel-cobalt alloy or an iron-nickel alloy for forming the ring  12 , and then deep drawing is applied a plurality of times, whereby a cylinder member  32  is formed which has a bottom having the diameter nearly equal to the outer diameter of the press fitting portion  12   a  of the ring  12 . In addition, the work position at which the cylinder member  32  is formed is accurately positioned by a pilot hole, not shown, formed in advance on the plate member  31 , whereby a plurality of the cylinder members  32  can be arranged and formed. 
   Subsequently, as shown in  FIG. 6B , sizing is performed to form the reducing portion  12   b  and the two step portions  12   e  and  12   f . In other words, the cylinder member  32  is molded in such a way that the portion to be the reducing portion  12   b  is further compressed to reduce the outer diameter thereof, and the portions to be the two step portions  12   e  and  12   f  are flat. Here, the two step portions  12   e  and  12   f  are formed nearly symmetrically to the center axis C 12 , whereby the reducing portion  12   b  can be formed in a uniform and nearly cylindrical shape without deforming the overall form. Then, as shown in  FIG. 6C , a bottom part  32   a  of each of the cylinder members  32  is punched to form a ceiling hole  32   b . Lastly, as shown in  FIG. 6D , blanking is performed to remove the cylinder member  32  from the plate member  31  for completing the ring  12 . 
   Subsequently, the ring  12 , the bar-shaped member to be the lead  13 , and the filler  14  are joined to each other. In other words, first, as a ring loading step S 22 , as shown in  FIG. 7 , a plurality of the rings  12  is mounted on a ring carbon jig  33  having a plurality of recessed parts  34 . The ring carbon jig  33  is formed of carbon so that it can be used in firing the filler  14  in a filler firing step S 25 , described later, which is a firing jig according to the invention. In addition, on the bottom side of the recessed part  34 , the recessed part  34  has a reducing portion  34   a  corresponding to the reducing portion  12   b  of the ring  12  and a flat portion  34   b  corresponding to the two step portions  12   e  and  12   f  of the ring  12  so that the ring  12  can be inserted downward. The orientation of each of the flat portions  34   b  of the plurality of the recessed parts  34  is formed to be nearly equal to each other. In addition, on the bottom surface side of the recessed part  34 , an insertion hole  33   a  is formed, into which the bar-shaped member can be inserted coaxially to the recessed part  34 . The depth of the insertion hole  33   a  is formed so that it can be matched with the length of the bar-shaped member to be the inner lead portion  15  of the lead  13  (on one end side thereof), and the bottom part side thereof is blocked with a bottom plate  33   b.    
   A plurality of the rings  12  is placed on the top of the ring carbon jig  33  in this configuration, and vibrations are applied to the ring carbon jig  33  to load the plurality of the rings  12  each into the recessed part  34  as the orientation is aligned. At this time, since the ring  12  is formed as the two step portions  12   e  and  12   f  are nearly symmetrically to the center axis C 12  and the ring  12  is formed in a nearly symmetric member overall, the ring  12  can be more smoothly loaded by vibrations. 
   Subsequently, as a filler inserting step S 23 , as shown in  FIG. 8 , the filler  14  is inserted into each of the rings  12  loaded in the recessed part  34  of the ring carbon jig  33 . Since the filler  14  has a shape before fired in the filler firing step S 25 , described later, the filler  14  has the outer diameter that the filler  14  can be inserted into the ring  12  as well as a shape having the through hole  14   a  into which the bar-shaped member can be inserted. Then, a plurality of the fillers  14  is placed on the top of the ring carbon jig  33  to apply vibrations to the ring carbon jig  33 , whereby each of the fillers  14  is inserted into the ring  12 . 
   Subsequently, as a lead inserting step S 24 , as shown in  FIG. 9 , the bar-shaped member  13   a  is inserted into the through hole  14   a  of the filler  14  that is inserted into the ring  12 . Here, as described above, the bar-shaped member  13   a  is a solid round bar to be the lead  13  in the hermetic terminal  4  as a completed product, in which the length thereof is formed longer than the length of the lead  13 . 
   In order to insert the bar-shaped member  13   a  like this into the through hole  14   a  of the filler  14 , first, on the top of the ring carbon jig  33  in which the rings  12  and the fillers  14  are loaded, a lead carbon jig  35  is set which is a firing jig according to the invention. The lead carbon jig  35  is formed with a plurality of through holes  35   a  into which the bar-shaped member  13   a  can be inserted. In addition, the ring carbon jig  33  and the lead carbon jig  35  have a positioning pin (not shown) and a positioning hole (not shown) at positions corresponding to each other, whereby the recessed part  34  is coaxially arranged and inserted into the through hole  35   a  in the state in which they are joined to each other. 
   Then, a plurality of the bar-shaped members  13   a  is placed on the top of the lead carbon jig  35  to apply vibrations to the ring carbon jig  33  and the lead carbon jig  35 , and then each of the bar-shaped members  13   a  is inserted into the through hole  14   a  of the filler  14  that is inserted into the ring  12 . Thus, each of the bar-shaped members  13   a  is joined to (put together with) the ring  12  and the filler  14  in the state in which the portion to be the inner lead portion  15  (one end side) is extended under the ring  12 , and the portion to be the first outer lead portion  16  (other end side) is extended above the ring  12 . 
   Here, the bar-shaped member  13   a  is inserted into the ring  12  in such a way that one end side of the bar-shaped member  13   a  to be inserted into the insertion hole  33   a  of the ring carbon jig  33  has the length, that is, the length corresponding to the insertion hole  33   a  denoted by L 1  in  FIG. 9 , longer than the length of the inner lead portion  15  in the hermetic terminal  4  as a completed product, that is, the length denoted by L 2  in  FIG. 2 , and then the bar-shaped member  13   a  is joined to the ring  12  and the filler  14 . In other words, the ring carbon jig  33  is formed to have the length L 1  of the insertion hole  33   a  longer than the length L 2  of the inner lead portion  15 , and the bar-shaped member  13   a  is inserted into the ring carbon jig  33  to the length L 1  of the insertion hole  33   a.    
   Here, preferably, the length L 1  of one end side of the bar-shaped member  13   a  corresponding to the length of the insertion hole  33   a  ranges from 1.5 times to 3 times the length L 2  of the inner lead portion  15  because of the reason below, described later; it is about two times in the embodiment. In addition, in the embodiment, the length of the bar-shaped member  13   a  is set to the other end projecting above the ring  12 , that is, the portion to be the first outer lead portion  16  in such a way that the length is nearly matched with the length of the first outer lead portion  16  in the hermetic terminal  4  as a completed product. 
   Subsequently, as the filler firing step S 25 , the filler  14  is fired as it is joined to the ring  12  and the bar-shaped member  13   a . In other words, as shown in  FIG. 10 , the ring carbon jig  33  and the lead carbon jig  35  are placed in the heating furnace as the ring  12 , the bar-shaped member  13   a  and the filler  14  are inserted therein, and they are heated at a temperature of 980° C. for about 13 hours, for example. Thus, the filler  14  is fired to hermetically seal the ring  12  to the bar-shaped member  13   a , and then, the ring  12 , the bar-shaped member  13   a  and the filler  14  are formed in one piece. Therefore, as shown in  FIG. 11 , the hermetic terminal intermediate  4   a  is formed. In the hermetic terminal intermediate  4   a  thus obtained, the length of one end side (inner lead portion)  15   b  of the bar-shaped member  13   a  is L 1  as discussed above, and is longer than the length L 2  of the inner lead portion  15  in the hermetic terminal  4  as a completed product. 
   Here, the hermetic terminal intermediate  4   a  uses the bar-shaped member  13   a  longer than the lead  12 , the one end side  15   b  to be the inner lead portion of the bar-shaped member  13   a  is inserted into the ring  12  so that the one end side  15   b  is longer than the inner lead portion  15 , and the hermetic terminal intermediate  4   a  is accommodated and fired in the ring carbon jig  33  and the lead carbon jig  35 , which are the firing jig. Thus, it is prevented that the one end side  15   b  extended from the ring  12  to be the inner lead portion becomes extremely shorter than the other end side to be the first outer lead portion in the firing jig. Therefore, as compared with the case in which the one end side  15   b  to be the inner lead portion is formed to have the same length as that of the inner lead portion  15  in the hermetic terminal  4  as a completed product, the one end side  15   b  and the other end side of the bar-shaped member  13   a  are extended relatively in good balance with respect to the ring  12 . Therefore, the degree that the bar-shaped member  13   a  is inclined to the center axis of the ring  12  is made smaller, whereby the bar-shaped member  13   a  is prevented from being eccentric to the ring  12 . 
   Subsequently, the hermetic terminal intermediate  4   a  is removed from the ring carbon jig  33  and the lead carbon jig  35 , and subjected to a plating step S 26 . In other words, as shown in  FIG. 12 , as the plating step S 26 , plating is applied to the outer side surface of the press fitting portion  12   a  and a part of the step portion  12   e  of the ring  12  and the bar-shaped member  13   a  in each of the hermetic terminal intermediate  4   a.    
   For example, the plating process includes base plating and finish plating, and for base plating, copper plating is used, for example. In addition, for finish plating, for example, a tin-copper alloy plating or gold plating is used, and particularly, gold plating is preferably used. In the ring  12 , the step portion  12   e  is a connecting portion for wire bonding, and one end side of the bar-shaped member  13   a  is the bump connecting portion  15   a  as described later. Thus, as finish plating, gold plating with more excellent connecting properties is preferable. 
   In addition, prior to such plating process, as pre-processing of plating, preferably, the surfaces of the bar-shaped member  13   a  and the ring  12  are cleaned, degreased with an alkaline solution, and acid washed with solutions of hydrochloric acid and sulfuric acid. 
   In addition, after the plating process, in order to stabilize the formed plating film (metal film), preferably, the plating film is annealed in a furnace in a vacuum atmosphere at a temperature of 170° C. for about one hour, for example. Thus, residual stress in the plating film can be removed. 
   Subsequently, as a setting step S 27 , the hermetic terminal intermediate  4   a  after plated is arranged and set on a holding member  36 .  FIGS. 13A and 13B  each show the holding member  36  before the hermetic terminal intermediates  4   a  are set thereon, and  FIGS. 14A and 14B  each show the holding member  36  after the hermetic terminal intermediates  4   a  are set thereon. Although not shown in  FIGS. 13A to 14B , the holding member  36  is a long resin product continued in a belt shape, on which a large number of hermetic terminal arranging parts  37  are formed at equal intervals in the length direction. The hermetic terminal arranging part  37  is configured of a pair of retaining parts  37   a  and  37   b . As shown in  FIGS. 14A and 14B , the retaining parts  37   a  and  37   b  are configured to retain the first outer lead portion (other end side)  16  of the bar-shaped member  13   a  in each of the hermetic terminal intermediates  4   a.    
   In the setting step S 27 , as shown in  FIGS. 14A and 14B , on the holding member  36  thus configured, the first outer lead portion (other end side)  16  of each of the hermetic terminal intermediates  4   a  formed in the previous step is retained on each of the hermetic terminal arranging parts  37  of the holding member  36 . At this time, the one end side  15   b  to be the inner lead portion  15  and the ring  12  are positioned outside the holding member  36 , and continuously arranged in the length direction of the holding member  36 . At this time, in the invention, since the setting step S 27  is performed prior to the flattening step, described later, it is unnecessary to align the orientation of the stair portion formed in the flattening step in one direction (upward) as the techniques before. Therefore, the hermetic terminal intermediate  4   a  can be easily set on the holding member  36 . 
   In addition, since the two step portions  12   e  and  12   f  of the ring  12  in the hermetic terminal intermediate  4   a  are formed nearly symmetrically to each other to the center axis C 12 , even though any one of the two step portions  12   e  and  12   f  is selected and placed as it is directed upward, wire bonding can be performed under the same conditions in a second mounting step S 42 , described later. In other words, since a plurality of the step portions is provided, in arranging the hermetic terminal intermediates  4   a , any one of the step portions to be the position for wire bonding later can be readily adjusted upward. 
   Subsequently, as a flattening step S 28 , the one end side  15   b  of the bar-shaped member  13   a  of each of the hermetic terminal intermediates  4   a  is flattened, and a stair portion  15   c  is formed on one side of the one end side  15   b  (the side to be flattened) in the bar-shaped member  13   a  as shown in  FIGS. 15A and 15B . In other words, while the holding member  36  is being moved intermittently, the tip end portion of the one end side  15   b  of each of the hermetic terminal intermediates  4   a  extended outside the holding member  36  is in turn flattened from above with a die  77  as shown in  FIGS. 16A to 16C , and a nearly half of the round bar shaped bar-shaped member  13   a  is made flat as shown in  FIG. 16C . 
   Here, in the embodiment, since the one end side  15   b  of the bar-shaped member  13   a  is inserted into the ring  12  in such a way that the one end side  15   b  is longer than the inner lead portion  15  in the hermetic terminal  4  as a completed product, the stair portion  15   c  formed by being flattened can be formed to have a relatively large area. In other words, the stair portion  15   c  is formed in such away that the length of the portion not to be the stair portion  15   c  in the one end side  15   b  is the same length as that of the corresponding portion in the hermetic terminal  4  as a completed product, whereby the a relatively longer range for flattening can be surely provided, which allows the stair portion  15   c  to be formed to have a relatively large area. 
   On the die  77  as a flattening tool, Ti—Cr is deposited in advance by an electro-deposition method to provide a Ti—Cr film having a thickness of about 1 mm at least on a flattening surface  77   a . Since the Ti—Cr film is hard with excellent durability, this hard film is provided on the flattening surface to form the flattening surface  77   a  into a smooth surface with no projections and depressions as well as to maintain the smoothness for a long time. Therefore, as described above, the flattening surface  77   a  is used to flatten the one end side  15   b  of the hermetic terminal intermediate  4   a  after plated, and no damage occurs in the plated surface of the stair portion  15   c  formed by being flattened because the flattening surface  77   a  is smooth. Thus, such a problem can be prevented that a plating is removed and transferred to the flattening surface  77   a  side. 
   In addition, the flattening step S 28  is performed after the filler firing step S 25  as in the embodiment, whereby it is unnecessary to adjust the relative orientations between the two step portions  12   e  and  12   f  of the ring  12  and the bump connecting portion  15   a  of the bar-shaped member  13   a  in the lead inserting step S 24  and the filler firing step S 25 . 
   Subsequently, as a shaping step S 29 , as indicated by chain double-dashed lines in  FIG. 17 , the tip end part and the two side parts of the stair portion  15   c  formed in the flattening step S 28  are cut with a cutting die (not shown), for example, the stair portion  15   c  is shaped into a nearly rectangle, for example, as depicted by a solid line in  FIG. 17 , and then the bump connecting portion  15   a  is formed substantially rectangularly. Thus, the one end side  15   b  of the bar-shaped member  13   a  becomes the inner lead portion  15 . As described above, since the stair portion  15   c  after flattened is partially cut into a predetermined shape, the bump connecting portion  15   a  obtained has a uniform shape and dimensions as designed. 
   Here, the margin for partially cutting the stair portion  15   c  to shape it into a predetermined shape is secured because the stair portion  15   c  is formed to have a relatively large area as described above. 
   Subsequently, as a bump forming step S 30 , as shown in  FIG. 18 , a pair of gold bumps  78  is formed at a predetermined position on the bump connecting portion  15   a , and then the hermetic terminal  4  as a completed product is obtained. For example, for the position of forming the gold bump  78 , based on the top edge and two side edges of the bump connecting portion  15   a , a position apart from a predetermined distance from these edges is determined, and the gold bump  78  is formed at this position. Therefore, as described above, since the stair portion  15   c  is shaped into a predetermined rectangle, the position of forming the gold bump  78  is as designed, and variations are suppressed. 
   Subsequently, as a holding member cutting step S 31 , as shown in  FIG. 19 , the holding member  36  in a belt shape is cut in every predetermined length. Thus, the holding member after cut is formed into a palette  38 , and  24  terminals of formed hermetic terminals  4 , for example are arranged and held on each of the palettes  38  in advance. Therefore, all the steps of the hermetic terminal fabricating process step S 20  are finished. 
   Subsequently, as the assembly process step S 40 , the piezoelectric vibrating piece  2 , the case  3 , and the hermetic terminal  4  are assembled. First, as a first mounting step S 41 , as shown in  FIGS. 20A and 20B , on the palette  38 , the piezoelectric vibrating piece  2  is mounted on the inner lead portion  15  of each of the hermetic terminals  4 . In other words, the piezoelectric vibrating piece  2  prepared in the piezoelectric vibrating piece producing process step S 10  is taken out of the dedicated palette  30 . Then, the first excitation electrode  8  of the taken piezoelectric vibrating piece  2  is connected to the formed bump connecting portion  15   a  on which the gold bumps  78  (not shown in  FIG. 20 ) are formed on the inner lead portion  15  of each of the hermetic terminals  4  through the bumps in the base portion  7 . At this time, it is the same as the techniques before that the gold bump  78  is used as the alignment mark for positioning. For the conditions of bump connection, for example, the mounting temperature is 130° C., the bonding load is 0.5 N, and the load time is about 15′ 10-3 seconds. Thus, the first excitation electrode of the piezoelectric vibrating piece  2  is electrically connected to the lead  13 , and the piezoelectric vibrating piece  2  is supported by the inner lead portion  15  of the lead  13  in an open-sided shape. 
   Here, as described above, since the gold bumps  78  are highly accurately arranged on the bump connecting portion  15   a  as designed, the piezoelectric vibrating piece  2  positioned relative to the bumps is also highly accurately connected to the position as designed. 
   In addition, since the bump connecting portion  15   a  is formed nearly flat in the flattening step, the conductivity between the first excitation electrode  8  and the lead  13  can be made more reliable as well as the piezoelectric vibrating piece  2  can be supported excellently by the lead  13 . In addition, since the bump connecting portion  15   a  is flattened to the position almost the same as the center axis of the lead  13 , the piezoelectric vibrating piece  2  can be connected to the lead  13  at the position almost the same as the center axis of the lead  13 . 
   Subsequently, as a second mounting step S 42 , as shown in  FIGS. 21A and 21B , the step portion  12   e  selected from the two step portions  12   e  and  12   f  of the ring  12  in each of the hermetic terminals  4  is wire bonded to the second excitation electrode  9  of the piezoelectric vibrating piece  2  mounted on each of the hermetic terminals  4 . In the embodiment, two wires  17  are bonded between the step portion  12   e  and the second excitation electrode  9 . For the wire  17  for use, for example, a gold (Au) line is selected, one end of the wire  17  is bonded to the second excitation electrode  9  in the base portion  7  of the piezoelectric vibrating piece  2 , and then the other end is bonded to the step portion  12   e  of the ring  12 . For the individual conditions for wire bonding, for example, the mounting temperature is 130° C., the wire diameter is 25 mm, the ball diameter is 80 to 85 mm, the ball thickness if 13 mm, and the shear strength is from 0.45 to 0.53 N; the bonding load is 0.55 N in bonding to the second excitation electrode  9 , and the load time is 7′ 10-3 seconds; and the bonding load is 0.4 N, and the load time is about 5′ 10-3 seconds in bonding to the step portion  12   e . Thus, the second excitation electrode  9  of the piezoelectric vibrating piece  2  is electrically connected to the ring  12 . Here, in the outer side surface of the reducing portion  12   b , the second excitation electrode  9  is bonded to the nearly flat step portion  12   e , whereby conductivity can be ensured. Particularly, the second excitation electrode  9  is connected with a plurality of the wires  17 , whereby conductivity can be more ensured. In addition, the filler  14  having the insulating properties is interposed between the lead  13  connected to the first excitation electrode  8  and the ring  12  connected to the second excitation electrode  9  to provide insulation therebetween, whereby the first excitation electrode  8  of the piezoelectric vibrating piece  2  is insulated from the second excitation electrode  9  to prevent short circuits. 
   Subsequently, as a fine tuning step S 43 , the piezoelectric vibrating piece  2  is finely tuned. In other words, as shown in  FIG. 22 , in the vacuum atmosphere, an electrode is contacted with a contact  39  provided on the outer side surface of the press fitting portion  12   a  of the ring  12  and on the palette  38 , and voltage is applied thereon, whereby the oscillating arm portions  5  and  6  of the piezoelectric vibrating piece  2  are oscillated. Then, the frequencies of the oscillating arm portions  5  and  6  are measured while a laser beam is applied onto the fine tuning part  10  to evaporate the metal film forming the fine tuning part  10 , whereby the piezoelectric vibrating piece  2  is finely tuned so that the vibrations of the oscillating arm portions  5  and  6  of the piezoelectric vibrating piece  2  can be a predetermined resonance frequency. 
   Subsequently, as a press fitting step S 44 , as shown in  FIG. 23 , in the vacuum atmosphere, each of the piezoelectric vibrating pieces  2  is inserted from the opening  3   a  of the case  3  formed in a predetermined shape in advance, and the ring  12  of the hermetic terminal  4  is press fitted into the case  3 , whereby the piezoelectric vibrating piece  2  is hermetically sealed in the case  3 . Lastly, as a separating step S 45 , as shown in  FIG. 24 , in the first outer lead portion  16  of the lead  13 , the portion fitted into the hermetic terminal arranging part  37  of the palette  38  is separated, and then the piezoelectric oscillator  1  is completed. 
   As described above, in the piezoelectric oscillator  1  according to in the embodiment, for the first excitation electrode  8  and the second excitation electrode  9  of the piezoelectric vibrating piece  2  arranged in the case  3 , the first excitation electrode  8  can externally conduct through the first outer lead portion  16  of the lead  13 , and the second excitation electrode  9  can externally conduct the second outer lead portion  18  of the case  3  through the ring  12  and the case  3  with no short circuits with each other. Here, the second excitation electrode  9  can be connected to the step portion  12   e  formed in the reducing portion  12   b  by providing the wire  17  with the use of the clearance  12   d  formed between the inner side surface of the case  3  and the step portion  12   e  of the ring  12 , and the outer diameters of the case  3  and the ring  12  will not become larger. In addition, since the ring  12  has a simple structure including the press fitting portion  12   a , the reducing portion  12   b , and the two step portions  12   e  and  12   f , even though the outer diameter thereof is reduced, the ring  12  can be readily formed by press working. On this account, in the piezoelectric oscillator  1  according to in the embodiment, the size can be reduced while short circuits can be prevented, and the piezoelectric oscillator  1  can be readily fabricated with excellent yields. In addition, the piezoelectric vibrating piece  2  is arranged at the position almost the same as the center axis of the lead  13  by the nearly flat bump connecting portion  15   a , whereby the piezoelectric vibrating piece  2  can be arranged at the position almost the same as the center axis C 3  of the case  3  together with the lead  13 . Therefore, the distance between the inner side surface of the case  3  and the piezoelectric vibrating piece  2  can be set to the minimum length depending on the range in which the piezoelectric vibrating piece  2  is displaced, and thus the case  3  and the ring  12  can be further reduced in size. 
   In addition, since the hermetic terminal  4  can be readily processed in such a way that the inner lead portion  15  can be easily flattened and the hermetic terminal intermediate can be easily set on the holding member, the mass production of the hermetic terminal  4 , the improvement of yields, and the cost reduction are allowed. Thus, the overall manufacture of the piezoelectric oscillator  1  can be facilitated as well, and the mass production, the improvement of yields, and the cost reduction are allowed. 
   In addition, in the embodiment, the hermetic terminal  4  with a single lead  13  and the piezoelectric oscillator  1  using the same are described, but the invention is not limited thereto. The invention can be adapted to the hermetic terminal with two leads as the hermetic terminal  73  of the piezoelectric oscillator  70  shown in  FIG. 30 . 
   Second Embodiment 
     FIGS. 25 and 26  each show a second embodiment of the invention. In the embodiment, the members overlapping with the members used in the embodiment described above are designated the same numerals and signs, omitting explanations. 
   As shown in  FIGS. 25 and 26 , this piezoelectric oscillator  50  according to the embodiment is a surface mounted piezoelectric oscillator in which the piezoelectric oscillator  1  according to the first embodiment is resin molded. More specifically, the piezoelectric oscillator  50  includes a case  3 , a hermetic terminal  4  which hermetically seals an opening  3   a  of the case  3 , a piezoelectric vibrating piece  2 , not shown, arranged inside the case  3 , and a resin body  51  which is formed of a resin for covering the case  3 , a first outer lead portion  16  and a second outer lead portion  18 . To each of the first outer lead portion  16  and the second outer lead portion  18 , an external terminal  52  is connected. The external terminal  52  includes a fitting portion  53  having a V-shape groove  53   a  into which the first outer lead portion  16  or the second outer lead portion  18  are fit, and an external connecting part  54  provided at the lower end of the fitting portion  53  and having a face  54   a  exposed outside the resin body  51 . 
   Also in the piezoelectric oscillator  50  like this, the excitation electrodes, not shown, provided on both surfaces of the piezoelectric oscillator are not short circuited to each other, and the size can be reduced, as well as the piezoelectric oscillator  50  can be readily fabricated. For example, for the outer shape of the resin body  51 , such a piezoelectric oscillator can be implemented in which one side is 1.1 mm or below in the cross section and the length is 4.3 mm or below. On this account, the piezoelectric oscillator  50  can be mounted on a substrate with a smaller space, and the space on the substrate can be saved. 
   Third Embodiment 
     FIG. 27  shows a third embodiment of the invention. In the embodiment, the members overlapping with the members used in the embodiment described above are designated the same numerals and signs, omitting explanations. 
     FIG. 27  shows a schematic diagram depicting the configuration of a tuning fork quartz crystal oscillator according to the invention, showing a plan view depicting a surface mounted piezoelectric oscillator using the piezoelectric oscillator discussed above. As shown in  FIG. 27 , in this oscillator  100  according to the embodiment, a cylinder package piezoelectric oscillator  1  is configured as an oscillating element electrically connected to an integrated circuit  101 . In addition, the piezoelectric oscillator  1  is the same as that of the first embodiment, omitting the explanations. The oscillator  100  has a substrate  103  on which an electronic component  102  such as a condenser is mounted. The substrate  103  is mounted with the integrated circuit  101  for the oscillator, and the piezoelectric oscillator  1  is mounted near the integrated circuit  101 . The electronic component  102 , the integrated circuit  101  and the piezoelectric oscillator  1  are electrically connected to each other through a wiring pattern, not shown. In addition, the individual components are molded with a resin, not shown. 
   In the oscillator  100  thus configured, voltage is applied to the piezoelectric oscillator  1 , a piezoelectric vibrating piece  2  in the piezoelectric oscillator  1  is oscillated, and the vibrations are converted into electric signals by the piezoelectric property of quartz crystal and inputted to the integrated circuit  101  as electric signals. The inputted electric signals are processed variously by the integrated circuit  101 , and outputted as frequency signals. Thus, the piezoelectric oscillator  1  functions as an oscillating element. In addition, for example, in the configuration of the integrated circuit  101 , an RTC (real time clock) module is selectively set in accordance with demands, whereby in addition to a single-function oscillator for clocks, such a function can be added that controls the operation dates and times of the oscillator and external devices or provides times and calendars. 
   As discussed above, in accordance with the oscillator  100  according to the embodiment, the small-sized piezoelectric oscillator  1  with no short circuits is included to provide a small-sized, highly reliable oscillator. 
   In addition, the oscillator  100  is described as it includes the cylinder package piezoelectric oscillator  1 , but which is not limited thereto, and which may include the surface mounted package piezoelectric oscillator  50  shown in the second embodiment, for example. 
   Fourth Embodiment 
     FIG. 28  shows a fourth embodiment of the invention. In the embodiment, the members overlapping with the members used in the embodiment described above are designated the same numerals and signs, omitting explanations. 
   In the embodiment, as an electronic appliance, a portable information device having the piezoelectric oscillator  1  described above is taken and described as an example.  FIG. 28  shows a block diagram depicting the configuration of this electronic appliance. As shown in  FIG. 28 , the portable information device  110  according to the embodiment has the piezoelectric oscillator  1  and a power supply part  111  for supplying electric power. For example, the power supply part  111  is configured of a lithium secondary battery. To the power supply part  111 , the following functional blocks are connected in parallel with each other: a control part  112  which performs various controls, a clock part  113  which counts time, a communicating part  114  which communicates with external devices, a display part  115  which displays various items of information, and a voltage detecting part  116  which detects voltage in the individual functional blocks. Then, the power supply part  111  supplies electric power to the individual functional blocks. 
   The control part  112  controls the individual functional blocks to perform operation control over the entire system such as sending and receiving sound data, measuring current time, and display. In addition, the control part  112  has a ROM in which a program is written in advance, a CPU which reads and performs the program written in the ROM, and a RAM used as the work area for the CPU. 
   The clock part  113  has an integrated circuit having an oscillation circuit therein, a register circuit, a counter circuit and an interface circuit and the piezoelectric oscillator  1 . Voltage is applied to the piezoelectric oscillator  1 , the piezoelectric vibrating piece  2  is then oscillated, and the vibrations are converted into electric signals by the piezoelectric property of quartz crystal, and inputted to the oscillation circuit as electric signals. The output of the oscillation circuit is binarized, and counted by the register circuit and the counter circuit. Then, through the interface circuit, signals are sent and received with the control part  112 , and the current time and current date or calendar information are displayed on the display part  115 . 
   The communicating part  114  has a function similar to that of a mobile telephone before, including a radio part  117 , a sound processing part  118 , a switching part  119 , an amplifying part  120 , a sound input/output part  121 , a telephone number input part  122 , a ringtone generating part  123  and a call control memory part  124 . The radio part  117  sends and receives various items of data such as sound data with a base station through an antenna  125 . The sound processing part  118  encodes and decodes sound signals inputted from the radio part  117  or the amplifying part  120 . The amplifying part  120  amplifies the signals inputted from the sound processing part  118  or the sound input/output part  121  to a predetermined level. The sound input/output part  121  is configured of a speaker and a microphone, which makes a ringtone or a received call loud or collects sounds. 
   In addition, the ringtone generating part  123  generates a ringtone in response to calling from the base station. The switching part  119  switches the amplifying part  120  connected to the sound processing part  118  to the ringtone generating part  123  only when a call is received, whereby the ringtone generated in the ringtone generating part  123  is outputted to the sound input/output part  121  through the amplifying part  120 . In addition, the call control memory part  124  stores therein a program for control of calling and called communications. In addition, the telephone number input part  122  has number keys 0 to 9 and other keys, for example, and these number keys are pressed to input the telephone number of a destination call. 
   In the case in which voltage applied to the individual functional blocks such as the control part  112  by the power supply part  111  is below a predetermined value, the voltage detecting part  116  detects this voltage drop and informs the control part  112  of the voltage drop. A predetermined voltage value at this time is a preset value as the minimum voltage necessary to stably operate the communicating part  114 , for example, about 3 V. The control part  112  informed of the voltage drop from the voltage detecting part  116  disables the operations of the radio part  117 , the sound processing part  118 , the switching part  119  and the ringtone generating part  123 . Particularly, it is required to stop the operation of the radio part  117  of large power consumption. Moreover, the display part  115  displays that the communicating part  114  is disabled for use because of battery shortage. 
   In other words, the voltage detecting part  116  and the control part  112  can disable the operation of the communicating part  114 , and show this on the display part  115 . This representation may be a text message, and for more intuitive representation, an X (cross) mark may be put on a telephone icon shown on the upper part of the display surface of the display part  115 . In addition, the portable information device  110  has a power source breaker  126  which can selectively shut down the power source for the function of the communicating part  114 , and the power source breaker  126  reliably disables the function of the communicating part  114 . 
   In accordance with the portable information device  110  according to the embodiment, the small-sized piezoelectric oscillator  1  with no short circuits is included to provide a small-sized, highly reliable portable information device. 
   In addition, the portable information device  110  is described as it includes the cylinder package piezoelectric oscillator  1 , but which is not limited thereto. For example, it may include the surface mounted package piezoelectric oscillator  50  shown in the second embodiment. The packaged piezoelectric oscillator  50  is preferable because it can be connected on a printed wiring board by reflow soldering together with other electronic components at the same time. 
   Fifth Embodiment 
     FIG. 29  shows a fifth embodiment of the invention. In the embodiment, the members overlapping with the members used in the embodiment described above are designated the same numerals and signs, omitting explanations. 
   In the embodiment, as an embodiment of a radio clock, a radio clock which has the piezoelectric oscillator  1  described above will be described.  FIG. 29  shows a block diagram depicting the configuration of the radio clock. As shown in  FIG. 29 , the radio clock  130  according to the embodiment has the piezoelectric oscillator  1  electrically connected to a filter part  131 , which is a clock having a function that receives standard radio waves including clock information and automatically corrects the radio waves to accurate time for display. In Japan, there are two transmitting stations (sending station) that send standard radio waves in Fukushima prefecture (40 kHz) and Saga prefecture (60 kHz), each sending standard radio waves. Since a long wave of 40 kHz or 60 kHz has a property of propagating through the earth&#39;s surface as well as a property of propagating while reflected in ionospheric layers and the earth&#39;s surface, the wave has a wide propagating area, covering throughout Japan with the two transmitting stations. 
   An antenna  132  receives standard radio waves of a 40 kHz or 60 kHz long wave. Standard radio waves of the long wave are waves in which time information called time code is amplitude modulated to a carrier wave of 40 kHz or 60 kHz. The received standard radio waves of the long wave are amplified by an amplifier  133 , and filtered and tuned by the filter part  131  having a plurality of the piezoelectric oscillators  1 . In addition, as the piezoelectric oscillator  1 , piezoelectric oscillator parts  134  and  135  are provided having resonance frequencies of 40 kHz and 60 kHz, respectively, the same as the carrier frequencies. 
   Moreover, the filtered signals at a predetermined frequency are detected and demodulated by a detector and rectifier circuit  136 . Then, the time code is taken out through a waveform shaping circuit  137 , and counted by a CPU  138 . The CPU  138  reads information such as the current year, the day of a year, the day of a week, and time. The read information is reflected in a RTC  139 , and accurate time information is displayed. Since the carrier wave is 40 kHz or 60 kHz, preferably, the piezoelectric oscillator parts  134  and  135  are the piezoelectric oscillator having the tuning fork structure described above. In the example of 60 kHz, for exemplary dimensions of a tuning fork oscillator piece, it can be configured in such dimensions that the overall length is about 2.8 mm, and the width dimension of the base portion is about 0.5 mm. 
   In accordance with the radio clock  130  according to the embodiment, the small-sized piezoelectric oscillator  1  with no short circuits is included to provide a small-sized, highly reliable radio clock. 
   In addition, the radio clock  130  is described as it includes the cylinder package piezoelectric oscillator  1 , but which is not limited thereto. For example, it may include the surface mounted package piezoelectric oscillator  50  shown in the second embodiment. 
   As discussed above, the embodiments of the invention have been described in detail with reference to the drawings. The vibration mode is not limited to bending oscillation of the tuning fork, which may be other vibration mode such as the thickness-shear vibration mode by other vibrating pieces. In addition, the material for a piezoelectric product is not limited to quartz crystal, which may be piezoelectric materials such as lithium niobate, lithium tantalate, and langasite. Moreover, the specific configuration is not limited to these embodiments, which includes design modifications within the scope not deviating from the teachings of the invention.