Patent Publication Number: US-2022216847-A1

Title: Piezoelectric vibrating device

Description:
TECHNICAL FIELD 
     The present invention relates to a piezoelectric vibration device for use in variously different electronic instruments including communication devices. 
     BACKGROUND ART 
     Surface-mounted piezoelectric vibrators and piezoelectric oscillators are typical examples of the piezoelectric vibration devices which have been and are currently used in a broad range of applications. For example, temperature-compensated piezoelectric oscillators operable to compensate frequency-temperature characteristics of piezoelectric vibrators are more commonly used as frequency sources for mobile communication devices that are often exposed to different thermal environments. 
     Such a temperature-compensated piezoelectric oscillator is equipped with an integrated circuit element that includes a temperature sensor and a temperature-compensated circuit. The temperature-compensated piezoelectric oscillator is configured to generate a compensation voltage to control an oscillation frequency based on temperatures detected by the temperature sensor embedded in the integrated circuit element (for example, patent literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2005-006030 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In such a surface-mounted, temperature-compensated piezoelectric oscillator, terminals for external connection are joined, with a joining material such as solder, to an external circuit board. When electronic components mounted to the external circuit board, which are a heat source (for example, power transistors), are turned on and supplied with electric current, the electronic components start to generate heat, and the generated heat is conducted to the terminals for external connection of the temperature-compensated piezoelectric oscillator mounted to this circuit board. 
     In the temperature-compensated piezoelectric oscillator, the integrated circuit element is directly connected to the terminals for external connection via, for example, an internal wiring, while the piezoelectric vibrator is connected to the integrated circuit element via an internal wiring. Thus, the piezoelectric vibrator is not directly connected to the terminals for external connection unlike the integrated circuit element. 
     Then, heat generated from the heat source of the external circuit board and conducted to the terminals for external connection of the temperature-compensated piezoelectric oscillator is then rapidly conducted to the integrated circuit element via the internal wiring and the terminals for external connection that excel in thermal conductivity. The temperature rise of the integrated circuit element may accordingly exhibit a sharper gradient than that of the piezoelectric vibrator, leading to greater temperature differences between the integrated circuit element and the piezoelectric vibrator. As a result, accurate temperature compensation may be difficult to perform, inviting frequency variations, i.e., generally called frequency drift, until the state of thermal equilibrium is reached between the piezoelectric vibrator and the integrated circuit element with less or no temperature difference between them. 
     This frequency drift may certainly occur when the electronic components; heat source, mounted to the external circuit board are turned on and supplied with electric current but may also occur when the electronic components are electrically turned off. When the electronic components; heat source; mounted to the external circuit board are electrically turned off, heat generated from the electronic components may no longer be conducted to the temperature-compensated piezoelectric oscillator, causing the temperature of the temperature-compensated piezoelectric oscillator to drop to lower degrees. At the time, heat from the integrated circuit element may be rapidly conducted to and radiated from the terminals for external connection via the internal wiring that excel in thermal conductivity. The temperature drop of the integrated circuit element may accordingly exhibit a sharper gradient than that of the piezoelectric vibrator, leading to greater temperature differences between the integrated circuit element and the piezoelectric vibrator. Then, the frequency drift may be likely to occur until the state of thermal equilibrium is reached between the piezoelectric vibrator and the integrated circuit element with less or no temperature difference between them. 
     Thus, the frequency drift may be inevitable in response to ON and OFF of electric current supply to the electronic components; heat source, of the external circuit board mounted with the temperature-compensated piezoelectric oscillator. This unfavorable event may be particularly noticeable with any electronic devices in which electronic components are electrically turned on and off relatively often. 
     The present invention addresses these issues and is directed to minimizing the risk of such undesired temperature differences that may occur between the piezoelectric vibrator and the integrated circuit element under heat conducted from the external circuit board mounted with the piezoelectric vibration device. 
     Solutions to the Problems 
     To this end, the present invention provides the following technical features. 
     A piezoelectric vibration device is provided that includes: 
     a piezoelectric vibrator including a plurality of terminals for external connection and a plurality of electrodes for mounting purpose; and 
     an integrated circuit element including a plurality of mounting terminals connectable to the plurality of electrodes for mounting purpose, the piezoelectric vibrator being mountable to the integrated circuit element. 
     The piezoelectric vibration device is further characterized in that 
     the piezoelectric vibrator includes: 
     a piezoelectric vibration plate including driving electrodes formed on main surfaces on both sides thereof; 
     a first sealing member allowed to cover and seal one of the main surfaces of the piezoelectric vibration plate; and 
     a second sealing member allowed to cover and seal the other one of the main surfaces of the piezoelectric vibration plate, 
     among the plurality of electrodes for mounting purpose, two paired electrodes for mounting purpose are electrically connected to the driving electrodes formed on the main surfaces, and a plurality of remaining electrodes for mounting purpose are electrically connected to the plurality of terminals for external connection, 
     the plurality of remaining electrodes for mounting purpose each have a wiring pattern for use in electrical connection between a respective one of the plurality of terminals for external connection and a respective one of the plurality of mounting terminals of the integrated circuit element, and 
     the wiring pattern in at least one of the plurality of remaining electrodes for mounting purpose has a constricted portion smaller in width than other portions thereof. 
     The present invention is characterized in that a plurality of remaining electrodes for mounting purpose, other than two paired electrodes for mounting purpose connected to the driving electrodes on the main surfaces of the piezoelectric vibration plate, each have a wiring pattern for use in electrical connection between a respective one of the terminals for external connection and a respective one of the mounting terminals of the integrated circuit element. The wiring pattern in at least one of the remaining ones of the electrodes for mounting purpose has a constricted portion smaller in width than the other portions that prevents the conduction of heat. In case heat is generated from a heat source in an external circuit board mounted with the piezoelectric vibration device, the generated heat may be conducted from the terminals for external connection of the piezoelectric vibration device to the integrated circuit element via the wiring patterns. According to the present invention, however, the constricted portion(s) of the wiring pattern(s) may prevent the heat thus generated from being conducted to the integrated circuit element. Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature rise. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     When, for example, the heat source of the external circuit board no longer generates heat, inviting the piezoelectric vibration device to drop its temperature to lower degrees, heat from the integrated circuit element may be conducted to and radiated from the terminals for external connection via the wiring patterns. According to the present invention, however, the conduction of heat at the time may be effectively prevented by the constricted portion(s) of the wiring pattern(s). Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature drop. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     The piezoelectric vibrator has a multilayered structure including three layers; the piezoelectric vibration plate having main surfaces on which the driving electrodes are formed, and the first and second sealing members covering and sealing the main surfaces. The piezoelectric vibrator thus structured may be advantageously reduced in thickness (reduced in height) as compared with, for example, such a packaging structure that piezoelectric vibration pieces are each housed in the housing space of a container and sealed with a lid member. 
     In a preferred embodiment of the piezoelectric vibration device according to the present invention, the wiring patterns in all of the plurality of remaining electrodes for mounting purpose may each have the constricted portion smaller in width. 
     According to the present invention, heat, if generated by the heat source of the external circuit board mounted with the piezoelectric vibration device and conducted from the terminals for external connection to the integrated circuit element via the wiring patterns, may be more effectively prevented from being thus conducted to the integrated circuit element. When, for example, the heat source of the external circuit board no longer generates heat, heat from the integrated circuit element possibly conducted to and radiated from the terminals for external connection via the wiring patterns may be more effectively prevented from being thus conducted to and radiated from these terminals. This may ensure more effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be more quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     In one embodiment of the piezoelectric vibration device according to the present invention, the plurality of electrodes for mounting purpose may be disposed on an outer surface of the first sealing member, the plurality of terminals for external connection may be disposed on an outer surface of the second sealing member, and the piezoelectric vibrator may include a plurality of through electrodes penetrating through the first sealing member, the piezoelectric vibration plate and the second sealing member in a direction of thickness thereof, and the plurality of remaining electrodes for mounting purpose may be electrically connected to the plurality of terminals for external connection via the plurality of through electrodes. 
     According to this embodiment, the terminals for external connection joined to the external circuit board are formed on the outer surface of the second sealing member on one surface of the piezoelectric vibrator, the electrodes for mounting purpose connected to the mounting terminals of the integrated circuit element are formed on the outer surface of the first sealing member on the other surface of the piezoelectric vibrator, and the plurality of remaining electrodes for mounting purpose are electrically connected to the plurality of terminals for external connection via the plurality of through electrodes penetrating through the first sealing member, the piezoelectric vibration plate and the second sealing member in a direction of their thickness. 
     In the piezoelectric vibration device thus characterized, heat generated by the heat source of the external circuit board mounted with the piezoelectric vibration device may be conducted to the mounting terminals of the integrated circuit element via the following electrodes and terminals of the piezoelectric vibration device; the remaining electrodes for mounting purpose, the through electrodes and the terminals for external connection that excel in thermal conductivity. In this instance, the conduction of heat at the time may be prevented by the constricted portion(s) of the wiring pattern(s) in the remaining electrodes(s) for mounting purpose, which may slow down the rate of thermal conduction to the integrated circuit element. Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature rise. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     When, for example, the heat source of the external circuit board no longer generates heat, heat from the integrated circuit element may be conducted from the mounting terminals to the remaining electrodes for mounting purpose, the through electrodes and the terminals for external connection, and then radiated from there. According to the present invention, however, the conduction of heat at the time may be effectively prevented by the constricted portion(s) of the wiring pattern(s) in the remaining electrodes for mounting purpose. Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature drop. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     In another embodiment of the piezoelectric vibration device according to the present invention, the constricted portion of the wiring pattern may be formed at a position closer to a respective one of the plurality of through electrodes than a connecting portion for connection between a respective one of the plurality of electrodes for mounting purpose and a respective one of the plurality of mounting terminals of the integrated circuit element. 
     According to this embodiment, the constricted portion(s) that serves to prevent the conduction of heat is formed at a position(s) closer to the through electrode(s) of the wiring pattern(s) for use in electrical connection between the through electrode(s) and the mounting terminal(s) of the integrated circuit element, i.e., at a position(s) away from the mounting terminals of the integrated circuit element. The conduction of heat may be thus controllable away from the mounting terminals of the integrated circuit element. 
     In yet another embodiment of the piezoelectric vibration device according to the present invention, the constricted portion of the wiring pattern may be formed outside of a mounting region where the integrated circuit element is mounted. 
     According to this embodiment, the constricted portions that serve to prevent the conduction of heat are formed in any region but the region where the integrated circuit element is mounted. Thus, the conduction of heat may be controllable away from the mounting region of the integrated circuit element. 
     In one embodiment of the piezoelectric vibration device according to the present invention, the constricted portion of the wiring pattern may be smaller than or equal to 40 μm in width. 
     In this embodiment that defines the constricted portion of the wiring pattern to 40 μm or less in width, the conduction of heat may be quite effectively controllable. 
     In yet another embodiment of the piezoelectric vibration device according to the present invention, the plurality of mounting terminals may be disposed at positions closer to an outer circumference of the integrated circuit element, and the two paired electrodes for mounting purpose electrically connected to the driving electrodes formed on the main surfaces may each have a wiring pattern for driving electrode extending more inward than the plurality of mounting terminals in the mounting region where the integrated circuit element is mounted. 
     According to this embodiment, the two paired electrodes for mounting purpose electrically connected to the driving electrodes formed on the main surfaces of the piezoelectric vibration plate in the piezoelectric vibrator each have a wiring pattern for driving electrode extending more inward than the mounting terminals in the mounting region of the integrated circuit element. In case the integrated circuit element is heated and elevated to higher temperature degrees than that of the piezoelectric vibrator, heat radiated from the heated integrated circuit element may heat the wiring patterns for driving electrode, and heat from these heated wiring patterns may be efficiently conducted to the piezoelectric vibrator. Thus, possible temperature differences between the integrated circuit element and the piezoelectric vibrator may be even more speedily minimized or reduced to zero, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     In yet another embodiment of the piezoelectric vibration device according to the present invention, the wiring patterns for driving electrode of the two paired electrodes for mounting purpose may be substantially symmetric to each other in which a point of symmetry is a central position of the mounting region of the integrated circuit element. 
     According to this embodiment characterized in that the wiring patterns for driving electrode of the two paired electrodes for mounting purpose are substantially point-symmetric about the central position of the mounting region of the integrated circuit element, the wiring patterns for driving electrode may be substantially equally heated by heat radiated from the integrated circuit element. Then, heat from the wiring patterns for driving electrode thus heated may be conducted to the main surfaces of the piezoelectric vibration plate, and temperatures of the main surfaces of the piezoelectric vibration plate may be both elevated to higher degrees in a balanced manner. 
     In a preferred embodiment of the piezoelectric vibration device according to the present invention, the wiring patterns for driving electrode of the two paired electrodes for mounting purpose may be at least extended as far as a near-center position in the mounting region of the integrated circuit element. 
     According to this embodiment characterized in that the wiring patterns for driving electrode of the electrodes for mounting purpose are at least extended as far as a near-center position in the mounting region of the integrated circuit element, the wiring patterns for driving electrode may be efficiently heated by heat radiated from a near-center part of the integrated circuit element driven and heated to high temperatures. Thus, heat from the heated wiring patterns for driving electrodes may be conducted to the piezoelectric vibrator, by which the piezoelectric vibrator may be efficiently heated and elevated to higher temperature degrees. 
     Effects of the Invention 
     The present invention is advantageously characterized in that the remaining electrodes for mounting purpose, other than the two paired electrodes for mounting purpose that are connected to the driving electrodes on the main surfaces of the piezoelectric vibration plate, each have a wiring pattern for use in electrical connection between a respective one of the terminals for external connection and a respective one of the mounting terminals of the integrated circuit element, and the wiring pattern in at least one of the remaining electrodes for mounting purpose has a constricted portion smaller in width than the other portions that prevents the conduction of heat. Possibly, heat generated from a heat source of the external circuit board mounted with the piezoelectric vibration device may be conducted, from the terminals for external connection of the piezoelectric vibration device, to the integrated circuit element via the wiring patterns. In case such an event occurs, however, the present invention may successfully prevent the conduction of heat at the time using the constricted portion(s) of the wiring pattern(s). Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature rise. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     When, for example, the heat source of the external circuit board no longer generates heat, heat from the integrated circuit element may be conducted to and radiated from the terminals for external connection via the wiring patterns. In case of such an event, heat from the integrated circuit element may be conducted, from the mounting terminals of this circuit element, to the terminals for external connection via the wiring patterns, and then radiated from there. According to the present invention, the conduction of heat at the time may be effectively prevented by the constricted portion(s) of the wiring pattern(s). Thus, the integrated circuit element may be allowed to have a moderate gradient of temperature drop. This may ensure effective control of possible temperature differences between the integrated circuit element and the piezoelectric vibrator, allowing the state of thermal equilibrium to be quickly reached between the integrated circuit element and the piezoelectric vibrator. 
     The piezoelectric vibrator has a multilayered structure including three layers; the piezoelectric vibration plate having main surfaces on which the driving electrodes are formed, and the first and second sealing members covering and sealing the main surfaces. The piezoelectric vibrator thus structured may be advantageously reduced in thickness (reduced in height) as compared with, for example, such a packaging structure that piezoelectric vibration pieces are each housed in the housing space of a container and sealed with a lid member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic structural view of a temperature-compensated crystal oscillator according to an embodiment of the present invention. 
         FIG. 2  is a schematic plan view illustrating the side of one main surface of a crystal vibration plate shown  FIG. 1 . 
         FIG. 3  is a schematic plan view illustrating the side of the other main surface of the crystal vibration plate seen through from the side of the one main surface of the crystal vibration plate shown  FIG. 1 . 
         FIG. 4  is a schematic plan view illustrating the side of one main surface of a first sealing member shown in  FIG. 1 . 
         FIG. 5  is a schematic plan view illustrating the side of the other main surface of the first sealing member seen through from the side of the one main surface of the first sealing member shown in  FIG. 1 . 
         FIG. 6  is a schematic plan view illustrating the side of one main surface of a second sealing member shown in  FIG. 1 . 
         FIG. 7  is a schematic plan view illustrating the side of the other main surface of the second sealing member seen through from the side of the one main surface of the second sealing member shown in  FIG. 1 . 
         FIG. 8  is a graphical illustration of a simulation result that represents a relationship between wiring length and heat conduction time. 
         FIG. 9  is a graphical illustration of a simulation result that represents a relationship between wiring width and heat conduction time. 
         FIG. 10  is a schematic structural view of a temperature-compensated crystal oscillator according to another embodiment of the present invention. 
         FIG. 11  is a schematic plan view illustrating the side of one main surface of a first sealing member according to the embodiment shown in  FIG. 10 . 
         FIG. 12  is a schematic plan view illustrating the side of one main surface of a first sealing member according to yet another embodiment of the present invention. 
         FIG. 13  is a schematic structural view of a temperature-compensated crystal oscillator according to yet another embodiment of the present invention. 
         FIG. 14  is a schematic plan view illustrating the side of one main surface of a first sealing member according to the embodiment shown in  FIG. 13 . 
         FIG. 15A  is a drawing that illustrates a modified example of a constricted portion in a wiring pattern shown in  FIG. 14 . 
         FIG. 15B  is a drawing that illustrates another modified example of the constricted portion in the wiring pattern shown in  FIG. 14 . 
         FIG. 15C  is a drawing that illustrates yet another modified example of the constricted portion in the wiring pattern shown in  FIG. 14 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present invention is hereinafter described with reference to the accompanying drawings. In this embodiment, a temperature-compensated crystal oscillator is described as an example of the piezoelectric vibration device according to the present invention. 
     First Embodiment 
       FIG. 1  is a schematic structural view of a temperature-compensated crystal oscillator according to an embodiment of the present invention. 
     A temperature-compensated crystal oscillator  1  according to this embodiment includes a crystal vibrator  2 , and an IC 3 ; integrated circuit element, mounted to the crystal vibrator  2 . 
     The crystal vibrator  2  includes a crystal vibration plate  4 ; an example of the piezoelectric vibration plate, a first sealing member  5  used to cover and air-tightly seal the side of one main surface of the crystal vibration plate  4 , and a second sealing member  6  used to cover and air-tightly seal the side of the other main surface of the crystal vibration plate  4 . 
     The crystal vibrator  2  is produced in the form of a sandwich-like multilayered package in which the first and second sealing members  5  and  6  are respectively joined to one and the other main surfaces of the crystal vibration plate  4 . The package of the crystal vibrator  2  has a cuboidal shape and is rectangular in plan view. In this embodiment, this package is in the size of, for example, 1.0 mm×0.8 mm in plan view and is thus reduced in size and height. 
     This package may be thus sized, or the size of this package may be selected from other applicable dimensions. 
     The IC 3  mounted to the crystal vibrator  2  is an integrated circuit element having a cuboidal outer shape in which an oscillator circuit, a temperature sensor and a temperature-compensated circuit are combined into one chip. 
     The crystal vibration plate  4  and the first and second sealing members  5  and  6  of the crystal vibrator  2  are hereinafter described. 
       FIG. 2  is a schematic plan view illustrating the side of one main surface of the crystal vibration plate  4 .  FIG. 3  is a schematic plan view illustrating the side of the other main surface of the crystal vibration plate  4  seen through from the one main-surface side. 
     In the description given below, a front surface is used to refer to one main surface closer to the IC 3  (upper side in  FIG. 1 ), and a back surface is used to refer to the other main surface away from the IC 3  (lower side in  FIG. 1 ).  FIG. 2  is a schematic plan view illustrating the front-surface side of the crystal vibration plate  4 , and  FIG. 3  is a schematic plan view illustrating the back-surface side of the crystal vibration plate  4  seen through from the front-surface side. 
     The crystal vibration plate  4  according to this embodiment is an AT-cut crystal plate, main surfaces of which on front and back sides are both XZ′ planes. 
     The crystal vibration plate  4  includes a substantially rectangular vibrating portion  41 , a frame portion  43  surrounding the vibrating portion  41  across a space (void)  12 , and a coupling portion  44  that allows the vibrating portion  41  and the frame portion  43  to be coupled to each other. The vibrating portion  41 , the frame portion  43  and the coupling portion  44  are formed as an integral unit. Though not illustrated in the drawings, the vibrating portion  41  and the coupling portion  44  are smaller in thickness than the frame portion  43 . 
     First and second driving electrodes  45  and  46  are formed in a pair on main surfaces on front and back sides of the vibrating portion  41 . First and second extraction electrodes  47  and  48  are respectively extracted from the first and second driving electrodes  45  and  46 . The first extraction electrode  47  on the front-surface side is extracted, via the coupling portion  44 , to a junction pattern  401  for connecting purpose formed in the frame portion  43 . The second extraction electrode  47  on the back-surface side is extracted, via the coupling portion  44 , to a junction pattern  402  for connecting purpose formed in the frame portion  43 . The junction pattern  402  for connecting purpose is formed so as to extend along a short side of the crystal vibration plate  4  rectangular in plan view and to surround a fifth through electrode  415  described later. 
     In this embodiment, the vibrating portion  41  is coupled to the frame portion  43  with the coupling portion  44  at one position. This may reduce any stress possibly acted upon the vibration portion  41 , as compared with the vibrating portion  41  being coupled to the frame portion  43  with the coupling portion  44  at two or more positions. 
     On the front and back main surfaces of the crystal vibration plate  4  are respectively formed first and second junction patterns  403  and  404  for sealing purpose serving to join the crystal vibration plate  4  to the first and second sealing members  5  and  6 . The first and second junction patterns  403  and  404  for sealing purpose on these main surfaces are formed in a circular shape along the outer circumference of the frame portion  43  and substantially along the outer peripheral edge of the crystal vibration plate  4  except its four corners. As illustrated in  FIG. 5 , a first junction pattern  51  for sealing purpose is formed on the back surface of the first sealing member  5 . This junction pattern  51  for sealing purpose is formed correspondingly to the first junction pattern  403  for sealing purpose on the front surface of the crystal vibration plate  4 . As illustrated in  FIG. 6 , a second junction pattern  61  for sealing purpose is formed on the front surface of the second sealing member  6 . This junction pattern  61  for sealing purpose is formed correspondingly to the second junction pattern  403  for sealing purpose on the back surface of the crystal vibration plate  4 . 
     As described later, the first sealing member  5 , the crystal vibration plate  4  and the second sealing member  6  are stacked in layers, and the circular first junction patterns  51  and  403  for sealing purpose of the first sealing member  5  and of the crystal vibration plate  4  are joined by diffusion bonding. Further, the circular second junction patterns  61  and  404  for sealing purpose of the second sealing member  6  and of the crystal vibration plate  4  are joined by diffusion bonding. Thus, the front and back surfaces of the crystal vibration plate  4  are sealed to each other with the first and second sealing members  5  and  6 , and a housing space is formed in which the vibrating portion  41  of the crystal vibration plate  4  is housed. 
     A package is thus formed in which the vibrating portion  41  is housed in a space formed by three layers of crystal plates; the crystal vibration plate  4  and the first and second sealing members  5  and  6  that are stacked on one another. This package, therefore, may be reduced in thickness (reduced in height), as compared with a crystal vibrator so structured that a crystal vibrating piece is housed in the housing recess of a ceramic container and sealed with a lid member joined to the container. 
     As illustrated in  FIGS. 2 and 3 , the crystal vibration plate  4  has five through electrodes; first to fifth through electrodes  411  to  415 . These electrodes are formed so as to penetrate through the front and back main surfaces of the crystal vibration plate  4 . In these through electrodes  411  to  415 , inner wall surfaces of through holes are each coated with a metal film. The first to fourth through electrodes  411  to  414  are formed at four corners of the crystal vibration plate  4  on the outer side of the circular first and second junction patterns  403  and  404  for sealing purpose. The fifth through electrode  415  is formed in the frame portion  43  on the inner side of the circular first and second junction patterns  403  and  404  for sealing purpose at a position close to a short side of the crystal vibration plate  4  rectangular in plan view. 
     Junction patterns  421  to  424  for connecting purpose are formed at positions around the through electrodes  411  to  414  at four corners on the front surface of the crystal vibration plate  4  on the outer side of the circular first junction pattern  403  for sealing purpose. The through electrodes  411  to  414  are electrically connected to these junction patterns  421  to  424  for connecting purpose. 
     Junction patterns  431  to  434  for connecting purpose are formed at positions around the through electrodes  411  to  414  at four corners on the back surface of the crystal vibration plate  4  on the outer side of the circular second junction pattern  404  for sealing purpose. The through electrodes  411  to  414  are electrically connected to these junction patterns  431  to  434  for connecting purpose. 
     As described later, the first sealing member  5  and the second sealing member  6  respectively have first to fourth through electrodes  501  to  504  and first to fourth through electrodes  601  to  604  that are formed correspondingly to the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4  (see  FIGS. 5 and 6 ). 
     As illustrated in  FIG. 2 , a junction pattern  425  for connecting purpose is formed around the fifth through electrode  415  on the front surface of the crystal vibration plate  4 . The fifth through electrode  415  and the junction pattern  425  for connecting purpose are electrically connected to each other. 
     As illustrated in  FIG. 3 , a junction pattern  402  for connecting purpose, which is connected to the extraction electrode  48  extracted from the second driving electrode  46 , is formed around the fifth through electrode  415  on the back surface of the crystal vibration plate  4 . The fifth through electrode  415  is electrically connected to this junction pattern  402  for connecting purpose and is thus electrically connected to the second driving electrode  46 . 
     On one side of the front surface of the crystal vibration plate  4  in a direction along its long sides across the vibrating portion  41  (lateral direction in  FIG. 2 ), a junction pattern  425  for connecting purpose is formed around the fifth through electrode  415 , and a junction pattern  401  for connecting purpose is formed to be continuous to the first extraction electrode  47 , as illustrated in  FIG. 2 . On the other side of the front surface of the crystal vibration plate  4  in the same direction are formed two junction patterns  441  and  442  for connecting purpose. 
     The junction patterns  425  and  401  for connecting purpose and the junction patterns  441  and  442  for connecting purpose are substantially symmetric with respect to a center line CL in the long-side direction of the crystal vibration plate  4 . Also, the junction patterns  425  and  441  for connecting purpose and the junction patterns  401  and  442  for connecting purpose are substantially symmetric with respect to a center line in the short-side direction of the crystal vibration plate  4 . Thus, the junction patterns  425  and  401  for connecting purpose and the junction patterns  441  and  442  for connecting purpose are substantially symmetric, respectively, in the long-side direction and in the short-side direction of the crystal vibration plate  4 . 
     Also, the junction patterns  421  to  424  for connecting purpose formed around the through electrodes  411  to  414  at four corners on the front surface of the crystal vibration plate  4  are symmetric, respectively, in the long-side direction and in the short-side direction of the crystal vibration plate  4 . 
     This structural feature; the junction patterns  425  and  401 ,  441  and  442 ,  421  to  424  being symmetric or substantially symmetric, respectively, in the long-side direction and in the short-side direction of the crystal vibration plate  4 , may allow a pressing force to be equally applied at the time of diffusion bonding. 
     As in the front surface of the crystal vibration plate  4 , the junction pattern  402  for connecting purpose extended to the fifth through electrode  415  is formed on the back surface of the crystal vibration plate  4 . The junction pattern  402  for connecting purpose is formed on one side in the long-side direction of the crystal vibration plate  4  across the vibrating portion  41  (lateral direction in  FIG. 3 ). Two junction patterns  451  and  452  for connecting purpose are formed on the other side in the long-side direction of the crystal vibration plate  4 . Similarly, the junction pattern  402  for connecting purpose and the junction patterns  451  and  452  for connecting purpose are substantially symmetric in the long-side direction and in the short-side direction of the crystal vibration plate  4 . 
     Also, the junction patterns  431  to  434  for connecting purpose formed around the through electrodes at four corners on the back surface of the crystal vibration plate  4  are symmetric in the long-side direction and in the short-side direction of the crystal vibration plate  4 . 
     The electrodes and junction patterns of the crystal vibration plate  4 ; first and second driving electrodes  45  and  46 , first and second extraction electrodes  47  and  48 , first and second junction patterns  403  and  404  for sealing purpose, and junction patterns  401 ,  402 ,  421  to  425 ,  431  to  434 ,  441 ,  442 ,  451  and  452  for connecting purpose, may each consist of, for example, a ground layer including Ti or Cr and an Au layer formed on the ground layer. 
       FIG. 4  is a schematic plan view illustrating the front-surface side of the first sealing member  5 .  FIG. 5  is a schematic plan view illustrating the back-surface side the first sealing member  5  seen through from the front-surface side. 
     The first sealing member  5  is a cuboidal substrate including an AT-cut crystal plate, similarly to the crystal vibration plate  4 . As illustrated in  FIG. 5 , the first sealing member  5  has, on its back surface, a first junction pattern  51  for sealing purpose to be joined for sealing to the first junction pattern  403  for sealing purpose on the front surface of the crystal vibration plate  4 . This first junction pattern  51  for sealing purpose is formed in a circular shape along the whole circumference of the first sealing member  5  and substantially along the outer peripheral edge of the first sealing member  5  except its four corners. 
     The first sealing member  5  has six through electrodes; first to sixth through electrodes  501  to  506 , which are formed so as to penetrate through the front and back main surfaces of the first sealing member  5 . In these through electrodes  501  to  506 , inner wall surfaces of through holes are each coated with a metal film. As with the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4 , the first to fourth through electrodes  501  to  504  are formed at four corners of the first sealing member  5  rectangular in plan view. The fifth through electrode  505  is formed, correspondingly to the junction pattern  441  for connecting purpose on the front surface of the crystal vibration plate  4 , at a position on the inner side of the circular first junction pattern  51  for sealing purpose close to a short side of the rectangular first sealing member  5 . The sixth through electrode  506  is formed, correspondingly to the junction pattern  401  for connecting purpose on the front surface of the crystal vibration plate  4 , at a position on the inner side of the circular first junction pattern  51  for sealing purpose close to the other short side of the rectangular first sealing member  5 . 
     As illustrated in  FIG. 5 , junction patterns  511  to  514  for connecting purpose are formed around the through electrodes  501  to  504  at four corners on the back surface of the first sealing member  5 . These through electrodes  501  to  504  are electrically connected, respectively, to the junction patterns  511  to  514  for connecting purpose. 
     A junction pattern  515  for connecting purpose is formed around the fifth through electrode  505  on the back surface of the first sealing member  5 . This fifth through electrode  505  is electrically connected to the junction pattern  515  for connecting purpose. A junction pattern  518  for connecting purpose is formed, correspondingly to the junction pattern  425  for connecting purpose on the front surface of the crystal vibration plate  4 , at a position on the opposite side of the junction pattern  515  for connecting purpose in the long-side direction of the first sealing member  5  (lateral direction in  FIG. 5 ). The junction pattern  518  for connecting purpose and the junction pattern  515  for connecting purpose formed around the fifth through electrode  505  are electrically connected to each other via a wiring pattern  519  for connecting purpose. The junction pattern  518  for connecting purpose on the back surface of the first sealing member  5  is, therefore, electrically connected to the fifth through electrode  505  of the first sealing member  5 . 
     As described later, the junction pattern  518  for connecting purpose of the first sealing member  5  is joined by diffusion bonding to the junction pattern  425  for connecting purpose formed around the fifth through electrode  415  on the front surface of the crystal vibration plate  4 . The junction pattern  518  for connecting purpose is thus electrically connected to the fifth through electrode  415  of the crystal vibration plate  4 . The fifth through electrode  415  of the crystal vibration plate  4  is electrically connected to the second driving electrode  46  formed on the back surface of the crystal vibration plate  4 . The junction pattern  518  for connecting purpose of the first sealing member  5  is thus electrically connected to the second driving electrode  46  of the crystal vibration plate  4 . The junction pattern  518  for connecting purpose of the first sealing member  5  is electrically connected to the junction pattern  515  for connecting purpose formed around the fifth through electrode  505  via the wiring pattern  519  for connecting purpose. Therefore, the second driving electrode  46  formed on the back surface of the crystal vibration plate  4  is electrically connected to the fifth through electrode  505  of the first sealing member  5  via the fifth through electrode  415  of the crystal vibration plate  4  and the junction patterns  518 ,  519  and  515  for connecting purpose of the first sealing member  5 . 
     A junction pattern  516  for connecting purpose is formed, correspondingly to the junction pattern  401  for connecting purpose on the front surface of the crystal vibration plate  4 , around the sixth through electrode  506  on the back surface of the first sealing member  5 . The sixth through electrode  506  is electrically connected to this junction pattern  516  for connecting purpose. On the opposite side of the junction pattern  516  for connecting purpose in the long-side direction of the first sealing member  5  (lateral direction on  FIG. 5 ), a junction pattern  517  for connecting purpose is formed correspondingly to the junction pattern  442  for connecting purpose on the front surface of the crystal vibration plate  4 . 
     As described later, the junction pattern  516  for connecting purpose of the first sealing member  5  is joined by diffusion bonding to the junction pattern  401  for connecting purpose formed on the front surface of the crystal vibration plate  4 . The junction pattern  516  for connecting purpose is, therefore, electrically connected to the first driving electrode  45  via the junction pattern  401  for connecting purpose and the first extraction electrode  47 . The sixth through electrode  506  of the first sealing member  5  is thus electrically connected to the first driving electrode  45  of the crystal vibration plate  4 . 
     As with the crystal vibration plate  4 , the junction patterns  515  to  518  for connecting purpose formed on the back surface of the first sealing member  5  are substantially symmetric in the long-side direction and in the short-side direction of the first sealing member  5  to allow a pressing force to be equally applied at the time of diffusion bonding. The junction patterns  511  to  514  for connecting purpose formed around the through electrodes  501  to  504  at four corners on the back surface of the first sealing member  5  are also symmetric in the long-side direction and in the short-side direction of the first sealing member  5 . 
     The front surface of the first sealing member  5  is a surface to be mounted with the IC 3 . In  FIG. 4  showing the front surface of the first sealing member  5 , virtual lines are used to illustrate the rectangular outer shape of the IC 3  in plan view mounted to the first sealing member  5  and outer shapes of the first to sixth mounting terminals  31  to  36  of the IC 3 . 
     As illustrated in  FIG. 4 , first to sixth electrodes  521  to  526  for mounting purpose are formed on the front surface of the first sealing member  5 . The first to sixth mounting terminals  31  to  36  of the IC 3  are respectively connected to these electrodes  521  to  526  for mounting purpose. 
     In a rectangular mounting region S defined with a virtual line where the IC 3  is mounted, the first to sixth electrodes  521  to  526  for mounting purpose have first to sixth terminal junctions  531  to  536  including electrode pads (not illustrated in the drawings) to which the mounting terminals  31  to  36  of the IC 3  are connectable. The first to sixth electrodes  521  to  526  for mounting purpose further have first to sixth electrode connectors  541  to  546  electrically connectable to the through electrodes  501 ,  505 ,  502 ,  503 ,  506  and  504 . These electrode connectors  541  to  546  are extending from the first to sixth terminal junctions  531  to  536  in the mounting region S toward the outside of the mounting region S. 
     As illustrated in  FIG. 1 , the IC 3  is joined, with a metallic member; metal bumps  7  (for example, Au bumps), to the front surface of the first sealing member  5  by the FCB (flip-chip bonding). Instead of the metal bumps  7 , metal plating or metal paste may be used for bonding. 
     An interval between the IC 3  and the first sealing member  5  is filled with a sealing resin; underfill resin  8 , to protect the acting surface of the IC 3  and to ensure an adequate mechanical bonding strength. 
     As with the first and second junction patterns  403  and  404  for sealing purpose of the crystal vibration plate  4 , the respective patterns and electrodes of the first sealing member  5 ; first junction pattern  51  for sealing purpose, junction patterns  511  to  518  for connecting purpose, wiring pattern  519  for connecting purpose, and first to sixth electrodes  521  to  526  for mounting purpose, may each consist of, for example, a ground layer including Ti or Cr and an Au layer formed on the ground layer. 
     The other technical aspects of the front surface of the first sealing member  5  will be described later. 
       FIG. 6  is a schematic plan view illustrating the front-surface side of the second sealing member  6 .  FIG. 7  is a schematic plan view illustrating the back-surface side of the second sealing member  6  seen through from the front-surface side. 
     The second sealing member  6  is a cuboidal substrate, including an AT-cut crystal plate, like the crystal vibration plate  4  and the first sealing member  5 . 
     As illustrated in  FIG. 6 , the second sealing member  6  has, on its front surface, a second junction pattern  61  for sealing purpose to be joined for sealing to the second junction pattern  404  for sealing purpose on the back surface of the crystal vibration plate  4 . This second junction pattern  61  for sealing purpose is formed in a circular shape along the whole circumference of the second sealing member  6  and substantially along the outer peripheral edge of the second sealing member  6  except its four corners. 
     The second sealing member  6  has four through electrodes; first to fourth through electrodes  601  to  604 , which are formed so as to penetrate through the front and back main surfaces of the second sealing member  6 . In these through electrodes  601  to  604 , inner wall surfaces of through holes are each coated with a metal film. Like the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4 , the first to fourth through electrodes  601  to  604  are formed at four corners of the rectangular shape in plan view of the second sealing member  6 . As illustrated in  FIG. 6 , junction patterns  611  to  614  for connecting purpose are formed around the through electrodes  601  to  604  at four corners on the front surface of the second sealing member  6 . The through electrodes  601  to  604  are electrically connected to the junction patterns  611  to  614  for connecting purpose. 
     At positions close to short sides of the second sealing member  6  on the inner side of the circular second junction pattern  61  for sealing purpose, four junction patterns in total; two junction patterns  621  and  622  for connecting purpose and two junction patterns  623  and  624  for connecting purpose, are formed correspondingly to the junction patterns  451 ,  452  and  402  for connecting purpose on the back surface of the crystal vibration plate  4 . 
     To allow a pressing force to be equally applied at the time of diffusion bonding, the junction patterns  621 ,  622 ,  623  and  624  for connecting purpose on the front surface of the second sealing member  6  and the junction patterns  611  to  614  for connecting purpose formed at four corners on the front surface are, in the same manner as with the crystal vibration plate  4 , substantially symmetric in the long-side direction and in the short-side direction of the second sealing member  6 . 
     As illustrated in  FIG. 7 , the second sealing member  6  has, on its back surface, four terminals; first to fourth terminals  631  to  634  for external connection, which are used to mount the temperature-compensated crystal oscillator  1  to an external circuit board. 
     In the illustrated example, the first terminal  631  for external connection is a terminal to be connected to a power supply. The second terminal  632  for external connection is a terminal for oscillation output. The third terminal  633  for external connection is a terminal for control voltage input. The fourth terminal  634  for external connection is a terminal for grounding. 
     The first to fourth terminals  631  to  634  for external connection are formed at four corners of the second sealing member  6  rectangular in plan view. The first to fourth through electrodes  601  to  604  are formed in the corner regions where the first to fourth terminals  631  to  634  for external connection are formed. These through electrodes  601  to  604  are thus electrically connected to the respective terminals  631  to  634  for external connection. 
     As with the first and second junction patterns  403  and  404  for sealing purpose of the crystal vibration plate  4 , the respective patterns and terminals of the second sealing member  6 ; the second junction pattern  61  for sealing purpose, the junction patterns  611  to  614  and  621  to  624  for connecting purpose and the first to fourth terminals  631  to  634  for external connection, may each consist of, for example, a ground layer including Ti or Cr and an Au layer formed on the ground layer. 
     Unlike the known art in which joining materials, such as adhesives, may be used, no exclusive joining material is used to join the crystal vibrator  2  to the target materials. The crystal vibrator  2  described in this embodiment is produced in the form of a sandwich-like package, as illustrated in  FIG. 1 , in which the crystal vibration plate  4  and the first sealing member  5  are joined by diffusion bonding, with the first junction patterns  403  and  51  for sealing purpose being stacked on each other, and the crystal vibration plate  4  and the second sealing member  6  are joined by diffusion bonding, with the second junction patterns  404  and  61  for sealing purpose being stacked on each other. Then, the housing space containing the vibrating portion  41  of the crystal vibration plate  4  is air-tightly sealed with the sealing members  5  and  6 . 
     In this instance, the first junction pattern  403  for sealing purpose of the crystal vibration plate  4  and the first junction pattern  51  for sealing purpose of the first sealing member  5  are combined by diffusion bonding into a joining material, and the second junction pattern  404  for sealing purpose of the crystal vibration plate  4  and the second junction pattern  61  for sealing purpose of the second sealing member  6  are combined by diffusion bonding into a joining material. 
     By performing the diffusion bonding under pressure, bonding strengths of the respective joining materials may be successfully improved. 
     During the diffusion bonding, the junction patterns for connecting purpose described earlier are stacked on and joined to each other by diffusion bonding and further joined firmly to each other with the joining materials generated as the result of diffusion bonding. 
     Specifically, the junction patterns  421  to  424  for connecting purpose formed at four corners on the front surface of the crystal vibration plate  4  are joined by diffusion bonding to the junction patterns  511  to  514  for connecting purpose formed at four corners on the back surface of the first sealing member  5 . The junction patterns  441  and  442  for connecting purpose formed at positions on the front surface of the crystal vibration plate  4  close to a short side thereof on the inner side of the circular first junction pattern  403  for sealing purpose are joined by diffusion bonding to the junction patterns  515  and  517  for connecting purpose on the back surface of the first sealing member  5 . The junction patterns  425  and  401  for connecting purpose formed at positions on the front surface of the crystal vibration plate  4  close to the other short side thereof on the inner side of the circular first junction pattern  403  for sealing purpose are joined by diffusion bonding to the junction patterns  518  and  516  for connecting purpose on the back surface of the first sealing member  5 . 
     Further, the junction patterns  431  to  434  for connecting purpose formed at four corners on the back surface of the crystal vibration plate  4  are joined by diffusion bonding to the junction patterns  611  to  614  on the front surface of the second sealing member  6 . The junction patterns  451  and  452  for connecting purpose formed at positions on the back surface of the crystal vibration plate  4  close to a short side thereof on the inner side of the circular second junction pattern  404  for sealing purpose are joined by diffusion bonding to the junction patterns  621  and  622  for connecting purpose on the front surface of the second sealing member  6 . The junction pattern  402  for connecting purpose at a position on the back surface of the crystal vibration plate  4  close to the other short side thereof on the inner side of the circular second junction pattern  404  for sealing purpose are joined by diffusion bonding to the junction patterns  623  and  624  for connecting purpose on the front surface of the second sealing member  6 . 
     The junction patterns  611  to  614  for connecting purpose on the front surface of the second sealing member  6  and the junction patterns  431  to  434  for connecting purpose on the back surface of the crystal vibration plate  4  are combined into joining materials by the diffusion bonding described above. Then, the first to fourth through electrodes  601  to  604 , which are electrically connected to the first to fourth terminals  631  to  634  for external connection on the back surface of the second sealing member  6 , are electrically connected, with these joining materials, to the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4 . 
     The junction patterns  421  to  424  for connecting purpose formed around the through electrodes  411  to  414  on the front surface of the crystal vibration plate  4  and the junction patterns  511  to  514  for connecting purpose on the back surface of the first sealing member  5  are combined into joining materials by the diffusion bonding described above. The, the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4  are electrically connected, with these joining materials, to the first to fourth through electrodes  501  to  504  of the first sealing member  5 . 
     Therefore, the first to fourth terminals  631  to  634  for external connection on the back surface of the second sealing member  6  are electrically connected, respectively, to the first to fourth through electrodes  411  to  414  of the crystal vibration plate  4  via the first to fourth through electrodes  601  to  604  of the second sealing member  6 . These first to fourth terminals  631  to  634  for external connection are further electrically connected, respectively, to the first to fourth through electrodes  501  to  504  of the first sealing member  5  via the first to fourth through electrodes  411  to  414 . 
     As illustrated in  FIG. 4 , the first to fourth through electrodes  501  to  504  of the first sealing member  5  are electrically connected, respectively, to the electrode connectors  541 ,  543 ,  544  and  546  of the first, third, fourth and sixth electrodes  521 ,  523 ,  524  and  526  for mounting purpose on the front surface of the first sealing member  5 . Therefore, the first to fourth terminals  631  and  634  for external connection of the second sealing member  6  are electrically connected, respectively, to the electrode connectors  541 ,  543 ,  544  and  546  of the first, third, fourth and sixth electrodes  521 ,  523 ,  524  and  546  for mounting purpose on the front surface of the first sealing member  5 . 
     The junction pattern  401  for connecting purpose, which is connected to the first driving electrode  45  on the front surface of the crystal vibration plate  4  illustrated in  FIG. 2  via the first extraction electrode  47 , is electrically connected to the sixth through electrode  506  of the first sealing member  5  with the joining material generated by the diffusion bonding of the junction pattern  516  for connecting purpose formed around the sixth through electrode  506  on the back surface of the first sealing member  5  illustrated in  FIG. 5 . As illustrated in  FIG. 4 , the sixth through electrode  506  of the first sealing member  5  is electrically connected to the fifth electrode connector  545  of the fifth electrode  525  for mounting purpose on the front surface of the first sealing member  5 . 
     The first driving electrode  45  of the crystal vibration plate  4  is, therefore, electrically connected to the fifth electrode connector  545  of the fifth electrode  525  for mounting purpose of the first sealing member  5  via the sixth through electrode  506  of the first sealing member  5 . 
     The fifth through electrode  415  electrically connected to the second driving electrode  46  on the back surface of the crystal vibration plate  4  illustrated in  FIG. 3  via the second extraction electrode  48  and the junction pattern  402  for connecting purpose is also electrically connected to the junction pattern  425  for connecting purpose on the front surface of the crystal vibration plate  4  illustrated in  FIG. 2 . The fifth through electrode  415  of the crystal vibration plate  4  is electrically connected, with the joining material generated by the diffusion bonding of the junction pattern  425  for connecting purpose of the crystal vibration plate  4  and the junction pattern  518  for connecting purpose on the back surface of the first sealing member  5  illustrated in  FIG. 5 , to the junction pattern  518  for connecting purpose on the back surface of the first sealing member  5 . The junction pattern  518  for connecting purpose on the back surface of the first sealing member  5  is connected to the junction pattern  515  for connecting purpose formed around the fifth through electrode  505  via the wiring pattern  519  for connecting purpose. The junction pattern  515  for connecting purpose on the back surface of the first sealing member  5  is electrically connected to the fifth through electrode  505 . As illustrated in  FIG. 4 , the fifth through electrode  505  is electrically connected to the second electrode connector  542  of the second electrode  522  for mounting purpose on the front surface of the first sealing member  5 . 
     The second driving electrode  46  on the back surface of the crystal vibration plate  4  is, therefore, electrically connected to the second electrode connector  542  of the second electrode  522  for mounting purpose on the front surface of the first sealing member  5  via the fifth through electrode  415  of the crystal vibration plate  4 , junction patterns  518 ,  519  and  515  for connecting purpose on the back surface of the first sealing member  5 , and the fifth through electrode  505  of the first sealing member  5 . 
     In the surface-mounted, temperature-compensated crystal oscillator  1  thus characterized, the first to fourth terminals  631  to  634  for external connection of the second sealing member  6  on the back-surface side of the crystal vibrator  2  illustrated in  FIG. 1  are mounted and joined with a bonding material, such as solder, to an external circuit board not illustrated in the drawing. 
     When an external circuit board mounted with electronic components; heat source, (for example, power transistors) is turned on and supplied with electric current, the electronic components start to generate heat. Then, heat generated then may be conducted to the first to fourth terminals  631  to  634  for external connection of the surface-mounted, temperature-compensated crystal oscillator  1  mounted to the external circuit board. 
     As described earlier, the IC 3  is directly connected to the first to fourth terminals for external connection  631  to  634  via the first to fourth through electrodes  601  to  604 ,  411  to  414  and  501  to  504  constituting in part the internal wiring. On the other hand, the first and second driving electrodes  45  and  46  of the crystal vibrator  2  are connected to the IC 3  and are thus not directly connected to the first to fourth terminals for external connection  631  to  634  on the back surface of the second sealing member  6 . 
     Therefore, any heat generated from the electronic components; heat source, mounted to the circuit board may be conducted to the temperature-compensated crystal oscillator  1  and further conducted rapidly to the IC 3  via the first to fourth through electrodes  601  to  604 ,  411  to  414  and  501  to  504  and the first to fourth terminals for external connection  631  to  634  that excel in thermal conductivity. Thus, the temperature rise of the IC 3  may exhibit a sharper gradient than that of the crystal vibrator  2 , resulting in greater temperature differences between the crystal vibrator  2  and the IC 3 . Then, accurate temperature compensation may be difficult to perform, leading to frequency variations, i.e., generally called frequency drift, until the state of thermal equilibrium is reached between the crystal vibrator  2  and the IC 3  with less or no temperature difference between them. 
     This frequency drift may also occur when the electronic components; heat source, mounted to the external circuit board are electrically turned off. When the electronic components mounted to the external circuit board are electrically turned off, heat generated from the electronic components may no longer be conducted to the temperature-compensated crystal oscillator  1 , causing the temperature of the temperature-compensated crystal oscillator  1  to drop to lower degrees. At the time, heat from the IC 3  may be rapidly conducted to the first to fourth terminals  631  to  634  for external connection via the first to fourth through electrodes  601  to  604 ,  411  to  414  and  501  to  504  having better thermal conductivity than the crystal vibrator  2 , and the heat conducted to these electrodes is then radiated. Thus, the temperature drop of the IC 3  may exhibit a sharper gradient than that of the crystal vibrator  2 . This may invite greater temperature differences between the crystal vibrator  2  and the IC 3 , leading to the frequency drift. 
     In order to prevent the occurrence of such an unfavorable event; frequency drift, this embodiment provides the following technical features for control of possible temperature differences generated between the IC 3  and the crystal vibrator  2  when the electronic components; heat source, mounted to the external circuit board are electrically turned on and off, so that the state of thermal equilibrium is quickly reached between these devices. 
     In this embodiment, the gradients of temperature rise and drop of the IC 3  when the electronic components; heat source; mounted to the external circuit board are electrically turned on and off may be rendered as moderate as possible to minimize possible temperature differences between the IC 3  and the crystal vibrator  2 . 
     Specifically, among the first to sixth electrodes  521  to  526  for mounting purpose on the front surface of the first sealing member  5  illustrated in  FIG. 4 , the first, third, fourth and sixth electrodes  521 ,  523 ,  524  and  526  for mounting purpose, except for two paired second and fifth electrodes  522  and  525  for mounting purpose that are connected to the first and second driving electrodes  45  and  46  of the crystal vibration plate  4 , respectively have first to fourth wiring patterns  571  to  574 . The first to fourth wiring patterns  571  to  574  provide electrical connection between the first, third, fourth and sixth electrode connectors  541 ,  543 ,  544  and  546  formed around the first to fourth through electrodes  501  to  504  and the first, third, fourth and sixth terminal junctions  531 ,  533 ,  534  and  536  to which the first, third, fourth and sixth mounting terminals  31 ,  33 ,  34  and  36  of the IC 3  are joined. The first to fourth wiring patterns  571  to  574  respectively have constricted portions  5711 ,  5722 ,  5733  and  5744  smaller in wiring width than the other portions. The constricted portions  5711 ,  5722 ,  5733  and  5744  are formed by cutting the wiring patterns  571  to  574  in part on one side into a rectangular shape. 
     For example, the constricted portions  5711 ,  5722 ,  5733  and  5744  may have a wiring width smaller than or equal to 100 μm or preferably smaller than or equal to 40 μm. In this embodiment, the wiring widths of these constricted portions are smaller than or equal to 40 μm. 
     A simulation test was performed to discuss how the rate of thermal conductivity changes with different wiring lengths and widths, the result of which is hereinafter described. 
     Two blocks connected to each other with a wiring were used. Then, this simulation test calculated the amounts of time required for the temperature of an outer surface of one of the blocks to reach 0.9° C. with different wiring lengths and widths when the temperature of an outer surface of the other block was fixed to 1° C. 
       FIG. 8  is a graph showing the amounts of time required for the outer surface temperature of one of the blocks to reach 0.9° C. with different wiring lengths, in which the lateral axis represents the wiring length, and the vertical axis represents the time.  FIG. 9  is a graph showing the amounts of time required for the outer surface temperature of one of the blocks to reach 0.9° C. with different wiring widths, in which the lateral axis represents the wiring width, and the vertical axis represents the time. 
     These graphs teach that it takes more time for the outer surface temperature of one of the blocks to reach 0.9° C. as the wiring that interconnects the two blocks is greater in length and smaller in width. 
     As illustrated in  FIG. 9 , there is not much difference among the amounts of time calculated with the wiring widths of approximately 40 μm or more, whereas the amounts of time suddenly and rapidly increase to approximately three times greater with the wiring widths of approximately 40 μm or less. 
     In this embodiment, the first to fourth wiring patterns  571  to  574  provide electrical connection between the first, third, fourth and sixth electrode connectors  541 ,  543 ,  544  and  546  formed around the first to fourth through electrodes  501  to  504  and the first, third, fourth and sixth terminal junctions  531 ,  533 ,  534  and  536  to which the first, third, fourth and sixth mounting terminals  31 ,  33 ,  34  and  36  of the IC 3  are joined, and these wiring patterns  571  to  574  respectively have constricted portions  5711 ,  5722 ,  5733  and  5744  smaller in wiring width than the other portions. These constricted portions  5711 ,  5722 ,  5733  and  5744  may serve to prevent the conduction of heat between the first to fourth through electrodes  501  to  504  and first, third, fourth and sixth terminal junctions  531 ,  533 ,  534  and  536  to which the first, third, fourth and sixth mounting terminals  31 ,  33 ,  34  and  36  of the IC 3  are joined. 
     When the electronic components; heat source, of the external circuit board mounted with the temperature-compensated crystal oscillator  1  are electrically turned on, the electronic components start to generate heat. Then, heat generated then may be conducted to the temperature-compensated crystal oscillator  1  and further conducted to the IC 3  via the first to fourth terminals for external connection  631  to  634 , the first to fourth through electrodes  601  to  604 ,  411  to  414  and  501  to  504 , and the first to fourth wiring patterns  571  to  574 . In this instance, the conduction of heat to the IC 3  may be prevented by the constricted portions  5711 ,  5722 ,  5733  and  5744  of the first to fourth wiring patterns  571  to  574 . As a result, the temperature rise gradient of the IC 3  may become moderate, allowing effective control of possible temperature differences between the IC 3  and the crystal vibrator  2 . Thus, the state of thermal equilibrium may be successfully reached between the IC 3  and the crystal vibrator  2 , and the frequency drift may be unlikely to occur. 
     When the electronic components; heat source; mounted to the external circuit board are electrically turned off, heat generated from the electronic components may no longer be conducted to the temperature-compensated crystal oscillator  1 , causing the temperature of the temperature-compensated crystal oscillator  1  to drop to lower degrees. At the time, heat from the IC 3  may be rapidly conducted from its first, third, fourth and sixth mounting terminals  31 ,  33 ,  34  and  36  of the IC 3  to the first to fourth terminals  631  to  634  for external connection via the first to fourth wiring patterns  571  to  574  and the first to fourth through electrodes  501  to  504 ,  411  to  414  and  601  to  604 , and the heat conducted to these terminals is then radiated. In this instance, the constricted portions  5711 ,  5722 ,  5733  and  5744  of the first to fourth wiring patterns  571  to  574  may successfully prevent the conduction of heat from IC 3  to the first to fourth through electrodes  501  to  504 . Thus, the temperature drop gradient of the IC 3  may become moderate, allowing effective control of possible temperature differences between the IC 3  and the crystal vibrator  2 . As a result, the state of thermal equilibrium may be quickly reached between the crystal vibration plate  4  and the IC 3 , and the frequency drift may be unlikely to occur. 
     In this embodiment, all of the wiring patterns  571  to  574  have the constricted portions; constricted portions  5711 ,  5722 ,  5733  and  5744 . In one embodiment of the present invention, at least one of these wiring patterns, instead of all of them, may be provided with a constricted portion. 
     Second Embodiment 
       FIG. 10  is a schematic structural view of a temperature-compensated crystal oscillator according to another embodiment of the present invention. This drawing is illustrated correspondingly to  FIG. 1 .  FIG. 11  is a schematic plan view illustrating the front-surface side of a first sealing member  5   a  in a crystal vibrator  2   a  provided in a temperature-compensated crystal oscillator  1   a  according to the embodiment shown in  FIG. 10 . This drawing is illustrated correspondingly to  FIG. 4 . In these drawings, the same reference signs as in the first embodiment or corresponding reference signs are appended to the same structural elements as described in the first embodiment or corresponding structural elements. 
     In this embodiment, any technical aspects but the electrode patterns on the front surface of the first sealing member  5   a  and an IC 3   a , i.e., the back-surface side of the first sealing member  5   a , the crystal vibration plate  4  and the second sealing member  6 , are substantially the same as described in the first embodiment illustrated in  FIGS. 2, 3 and 5 to 7 . These like components and features, therefore, will not be described again in this embodiment. 
     In this embodiment, a direction in which the IC 3   a  is mounted relative to the first sealing member  5   a  differs from what is described in the first embodiment, and electrode patterns of the first sealing member  5   a  accordingly differ from what is described in the first embodiment. In the first embodiment, the IC 3  is mounted so that its long-side direction is orthogonal to the long-side direction of the first sealing member  5 , as illustrated in  FIG. 4 . On the other hand, the IC 3   a  is mounted in this embodiment so that its long-side direction is parallel to the long-side direction of the first sealing member  5   a , as illustrated in  FIG. 11 . 
     In  FIG. 11  illustrating the front-surface side of the first sealing member  5   a , virtual lines are used to illustrate the rectangular outer shape in plan view of the IC 3   a  mounted to the first sealing member  5   a , and outer shapes of first to sixth mounting terminals  31   a  to  36   a  and a temperature sensor  301   a.    
     As illustrated in  FIG. 11 , the first sealing member  5   a  has, on its front surface, first to sixth electrodes  521   a  to  526   a  for mounting purpose. The first to sixth mounting terminals  31   a  to  36   a  of the IC 3   a  are respectively connected to these electrodes  521   a  to  526   a  for mounting purpose. 
     In a rectangular mounting region Sa defined with a virtual line where the IC 3   a  is mounted, the first to sixth electrodes  521   a  to  526   a  for mounting purpose have first to sixth terminal junctions  531   a  to  536   a  including electrode pads (not illustrated in the drawings) to which the mounting terminals  31   a  to  36   a  of the IC 3   a  are connectable. The first to sixth electrodes  521   a  to  526   a  for mounting purpose further have first to sixth electrode connectors  541   a  to  546   a  electrically connectable to the through electrodes,  501 ,  505 ,  503 ,  502 ,  506  and  504 . These electrode connectors  541   a  to  546   a  are extending from the first to sixth terminal junctions  531   a  to  536   a  in the mounting region Sa toward the outside of the mounting region Sa. 
     Of the first to sixth electrodes  521   a  to  526   a  for mounting purpose on the front surface of the first sealing member  5   a , the first, fourth, third and sixth electrodes  521   a ,  524   a ,  523   a  and  526   a  for mounting purpose, except for two paired second and fifth electrodes  522   a  and  525   a  for mounting purpose that are connected to the first and second driving electrodes  45  and  46  of the crystal vibration plate  4 , respectively have first to fourth wiring patterns  571   a  to  574   a . The first to fourth wiring patterns  571   a  to  574   a  provide electrical connection between the first, fourth, third and sixth electrode connectors  541   a ,  544   a ,  543   a  and  546   a  around the first to fourth through electrodes  501  to  504  and the first, fourth, third and sixth terminal junctions  531   a ,  534   a ,  533   a  and  536   a  to which the first, fourth, third and sixth mounting terminals  31   a ,  34   a ,  33   a  and  36   a  of the IC 3   a  are joined. These wiring patterns  571   a  to  574   a  respectively have constricted portions  5711   a ,  5722   a ,  5733   a  and  5744   a  smaller in wiring width than the other portions. 
     Thus, the first, fourth, third and sixth electrode connectors  541   a ,  544   a ,  543   a  and  546   a  around the first to fourth through electrodes  501  to  504  of the first sealing member  5   a  are electrically connected, via the first to fourth wiring patterns  571   a  to  574   a , to the first, fourth, third and sixth terminal junctions  531   a ,  534   a ,  533   a  and  536   a  to which the first, fourth, third and sixth mounting terminals  31   a ,  34   a ,  33   a  and  36   a  of the IC 3   a  are joined, and these wiring patterns  571   a  to  574   a  that thus provide electrical connection between these electrode connectors and terminal junctions respectively have the constricted portions  5711   a ,  5722   a ,  5733   a  and  5744   a  smaller in wiring width than the other portions. These constricted portions  5711   a ,  5722   a ,  5733   a  and  5744   a  may effectively prevent the conduction of heat between the first to fourth through electrodes  501  to  504  and the first, fourth, third and sixth terminal junctions  531   a ,  534   a ,  533   a  and  536   a  to which the first, fourth, third and sixth mounting terminals  31   a ,  34   a ,  33   a  and  36   a  of the IC 3   a  are joined. 
     In this manner, the temperature rise gradient of the IC 3   a  may become moderate when the electronic components; heat source, of the external circuit board mounted with the temperature-compensated crystal oscillator  1   a  are electrically turned on. Further advantageously, the temperature drop gradient of the IC 3   a  may also become moderate when the electronic components; heat source, of the external circuit board are electrically turned off. Thus, possible temperature differences between the IC 3   a  and the crystal vibrator  2   a  may be controlled, and the state of thermal equilibrium may be quickly reached between these devices. As a result, the frequency drift may be unlikely to occur. 
     In this embodiment, the sixth through electrode  506  of the first sealing member  5   a  electrically connected to the first driving electrode  45  of the crystal vibration plate  4  is electrically connected to the fifth electrode connector  545   a  of the fifth electrode  525   a  for mounting purpose, similarly to the first embodiment. The first driving electrode  45  of the crystal vibration plate  4 , therefore, is electrically connected to the fifth electrode connector  545   a  of the fifth electrode  525   a  for mounting purpose of the first sealing member  5   a  via the sixth through electrode  506  of the first sealing member  5   a.    
     Further, the fifth through electrode  505  of the first sealing member  5   a  electrically connected to the second driving electrode  46  of the crystal vibration plate  4  is electrically connected to the second electrode connector  542   a  of the second electrode  522   a  for mounting purpose, similarly to the first embodiment. The second driving electrode  46  on the back surface of the crystal vibration plate  4 , therefore, is electrically connected to the second electrode connector  542   a  of the second electrode  522   a  for mounting purpose on the front surface of the first sealing member  5   a  via the fifth through electrode  505  of the first sealing member  5   a.    
     In this embodiment, the following technical features are provided to allow the state of thermal equilibrium to be quickly reached between the IC 3   a  and the crystal vibrator  2  without any temperature difference therebetween even when the IC 3   a  is heated to higher temperatures than the crystal vibrator  2 . 
     As illustrated in  FIG. 11 , the first to sixth mounting terminals  31   a  to  36   a  of the IC 3   a  are disposed at positions close to the outer circumference of the IC 3   a  rectangular in plan view. Specifically, the first to sixth mounting terminals  31   a  to  36   a  are disposed at positions close to a respective one of long sides; a pair of opposing sides in two pairs of opposing sides of the rectangular shape, and are arranged in two rows along the long sides. The one of two pairs of opposing sides may be “short sides” instead of the “long sides”. 
     In this embodiment, of the first to sixth electrodes  521   a  to  526   a  for mounting purpose formed on the front surface of the first sealing member  5   a , the second and fifth electrodes  522   a  and  525   a  that are paired and connected to the driving electrodes  46  and  45  of the crystal vibration plate  4  respectively have a fifth wiring pattern  565  and a sixth wiring pattern  566 . The fifth wiring pattern  565  and the sixth wiring pattern  566  are wiring patterns for driving electrode that are extending inward in the mounting region Sa rectangular in plan view where the IC 3   a  is mounted. The wiring patterns  565  and  565  are formed in a large width, so that areas of these wiring patterns facing the IC 3   a  in the mounting region Sa are adequately large. 
     In the rectangular mounting region Sa, the fifth and sixth wiring patterns  565  and  566  are extending in the long-side direction of the IC 3   a  (lateral direction on  FIG. 11 ) between the first to third mounting terminals  31   a  to  33   a  and the fourth to six mounting terminals  34   a  to  36   a  of the IC 3   a  that are arranged in two rows. The fifth and sixth wiring patterns  565  and  566  are then each diagonally bent at a near-center position and extending toward the second and fifth mounting terminals  32   a  and  35   a . The fifth wiring pattern  565  is extending so as to exactly overlap with a rectangular region of projection where the temperature sensor  301   a  embedded in the IC 3   a  is projected in the mounting region Sa. 
     In the mounting region Sa where the IC 3   a  is mounted, the fifth and sixth wiring patterns  565  and  566  large in width of the paired second and fifth electrodes  522   a  and  525   a  that are respectively connected to the driving electrodes  46  and  45  of the crystal vibration plate  4  are formed in a manner that these wiring patterns face the IC 3   a.    
     In case the temperature of the IC 3   a  reaches higher degrees than that of the crystal vibrator  2   a , resulting in temperature differences between the IC 3   a  and the crystal vibrator  2   a , heat radiated from the IC 3   a  heats the fifth and sixth wiring patterns  565  and  566  that are disposed immediately below the IC 3   a  and are facing the IC 3 . 
     The fifth and sixth wiring patterns  565  and  566  are extending from the electrode connectors  542   a  and  545   a  of the second and fifth electrodes  522   a  and  525   a  for mounting purpose. The electrode connectors  542   a  and  545   a  are electrically connected to the fifth and sixth through electrodes  505  and  506 . The fifth through electrode  505  is connected to the second driving electrode  46  on the back surface of the crystal vibration plate  4 , while the sixth through electrode  506  is connected to the first driving electrode  45  on the front surface of the crystal vibration plate  4 . 
     The fifth and sixth wiring patterns  565  and  566  are thus respectively connected to the driving electrodes  46  and  45  of the crystal vibration plate  4 . When heat is radiated from the heated IC 3   a  and the wiring patterns  565  and  566  are thereby heated, therefore, heat radiated from the heated wiring patterns  565  and  566  is conducted to the driving electrodes  46  and  45  of the crystal vibration plate  4  and heat these driving electrodes. 
     Then, heat is radiated from the IC 3   a  heated to higher temperature degrees than that of the crystal vibrator  2   a , and the IC 3   a  cools down to lower temperature degrees. On the other hand, the crystal vibrator  2   a  is exposed to heat conducted from the second wiring pattern  562  and the fifth wiring pattern  565  heated by the heat radiation from the IC 3   a . This may effectively control possible temperature differences between the IC 3   a  and the crystal vibrator  2   a , allowing the state of thermal equilibrium to be quickly reached between these devices. 
     Any difference between the temperature of the crystal oscillator  2  and the temperature detected by the temperature sensor  301  of the IC 3  may possibly invite frequency variations. Such an unfavorable event, however, may be effectively controlled, and accurate temperature compensation may be thus successfully performed. 
     In the second electrode  522   a  for mounting purpose having the fifth wiring pattern  565  and the fifth electrode  525   a  for mounting purpose having the sixth wiring pattern  566  according to this embodiment, their patterns are formed to be point-symmetric about a central position O of the mounting region Sa rectangular in plan view. Thus, the fifth wiring pattern  565  and the sixth wiring pattern  566  may be efficiently heated by being exposed to the heat radiated from the heated IC 3   a  in a balanced manner. 
     This embodiment may be particularly advantageous in that the fifth wiring pattern  565  is formed so as to entirely include the region of projection of the temperature sensor  301  embedded in the IC 3   a . Therefore, the fifth wiring pattern  565  immediately below and facing the temperature sensor  301   a  may be heated by heat radiated from a part of the IC 3   a  where this temperature sensor is disposed, and heat from the fifth wiring pattern  565  thus heated may be conducted to the crystal vibration plate  4  of the crystal vibrator  2   a . As a result, the state of thermal equilibrium may be quickly reached between the crystal vibration plate  4  and a part of the IC 3   a  where the temperature sensor  301   a  is disposed, and accurate temperature compensation may be successfully performed. 
     Any other structural and technical features and effects of this embodiment are similar to what is described in the first embodiment. 
       FIG. 12  is a schematic plan view illustrating the front-surface side of a first sealing member  5   b  in a crystal vibrator of a temperature-compensated crystal oscillator according to yet another embodiment of the present invention. This drawing is illustrated correspondingly to  FIG. 11 . 
     In this embodiment, any technical aspects but the electrode patterns on the front surface of the first sealing member  5   b  and an IC 3   b , i.e., the back-surface side of the first sealing member  5   b , the crystal vibration plate  4  and the second sealing member  6 , are substantially the same as described in the embodiment illustrated in  FIGS. 10 and 11 . These like components and features, therefore, will not be described again in this embodiment. 
     In this embodiment, a direction in which the IC 3   b  is mounted relative to the first sealing member  5   b  differs from what is described in the embodiment illustrated in  FIG. 11 , and electrode patterns of the first sealing member  5   b  are accordingly formed differently from what is described in the earlier embodiment. In the earlier embodiment, the IC 3   a  is mounted so that its long-side direction is parallel to the long-side direction of the first sealing member  5   a , as illustrated in  FIG. 11 . On the other hand, the IC 3   b  is mounted in this embodiment so that its long-side direction is orthogonal to the long-side direction of the first sealing member  5   b , as illustrated in  FIG. 12 . 
     As illustrated in  FIG. 11 , the first sealing member  5   b  has, on its front surface, first to sixth electrodes  521   b  to  526   b  for mounting purpose. The first to sixth mounting terminals  31   b  to  36   b  of the IC 3   b  are respectively connected to the first to sixth electrodes  521   b  to  526   b  for mounting purpose correspondingly to how these mounting terminals  31   b  to  36   b  are arranged. 
     In a rectangular mounting region Sb defined with a virtual line where the IC 3   b  is mounted, the first to sixth electrodes  521   b  to  526   b  for mounting purpose have first to sixth terminal junctions  531   b  to  536   b  including electrode pads (not illustrated in the drawings) to which the mounting terminals  31   b  to  36   b  of the IC 3   b  are connectable. The first to sixth electrodes  521   b  to  526   b  for mounting purpose further have first to sixth electrode connectors  541   b  to  546   b  electrically connectable to the through electrode  501 ,  505 ,  502 ,  503 ,  506  and  504 . These electrode connectors  541   b  to  546   b  are extending from the first to sixth terminal junctions  531   b  to  536   b  in the mounting region Sb toward the outside of the mounting region Sb. 
     Among the first to sixth electrodes  521   b  to  526   b  for mounting purpose on the front surface of the first sealing member  5   b , the first, third, fourth and sixth electrodes  521   b ,  523   b ,  524   b  and  526   b  for mounting purpose, except for the second and fifth electrodes  522   b  and  525   b  for mounting purpose that are paired and connected to the first and second driving electrodes  45  and  46  of the crystal vibration plate  4 , respectively have first to fourth wiring patterns  571   b  to  574   b . The first to fourth wiring patterns  571   bb  to  574  provide electrical connection between the first, third, fourth and sixth electrode connectors  541   b ,  543   b ,  544   b  and  546   b  formed around the first to fourth through electrodes  501  to  504  and the first, third, fourth and sixth terminal junctions  531   b ,  533   b ,  534   b  and  536   b  to which the first, third, fourth and sixth mounting terminals  31   b ,  33   b ,  34   b  and  36   b  of the IC 3  are joined. These wiring patterns  571   b  to  574   b  respectively have constricted portions  5711   b ,  5722   b ,  5733   b  and  5744   b  smaller in wiring width than the other portions. 
     Thus, the first to fourth wiring patterns  571   b  to  574   b  provide electrical connection between the first to fourth through electrodes  501  to  504  of the first sealing member Sb and the first, third, fourth and six terminal junctions  531   b ,  533   b ,  534   b  and  536   b  to which the IC 3   b  is joined, third, fourth and sixth electrode connectors  541 ,  543 ,  544  and  546  formed, and these wiring patterns  571   b  to  574   b  respectively have constricted portions  5711   b ,  5722   b ,  5733   b  and  5744   b  smaller in wiring width than the other portions. These constricted portions  5711   b ,  5722   b ,  5733   b  and  5744   b  may serve to prevent the conduction of heat between the first to fourth through electrodes  501  to  504  and the first, third, fourth and six terminal junctions  531   b ,  533   b ,  534   b  and  536   b  to which the IC 3   b  is joined. 
     In this manner, the temperature rise gradient of the IC 3   b  may become moderate when the electronic components; heat source, of the external circuit board mounted with the temperature-compensated crystal oscillator  1   a  are electrically turned on. Further advantageously, the temperature drop gradient of the IC 3   b  may also become moderate when the electronic components; heat source, of the external circuit board are electrically turned off. Thus, possible temperature differences between the IC 3   b  and the crystal vibrator may be controlled, and the state of thermal equilibrium may be quickly reached between these devices. As a result, the frequency drift may be unlikely to occur. 
     In this embodiment, among the first to sixth electrodes  521   b  to  526   b  for mounting purpose on the front surface of the first sealing member  5   b , the second and fifth electrodes  522   b  and  525   b  that are paired and connected to the driving electrodes  46  and  45  of the crystal vibration plate  4  respectively have a fifth wiring pattern  565   b  and a sixth wiring pattern  566   b . The fifth wiring pattern  565   b  and the sixth wiring pattern  566   b  are wiring patterns for driving electrode that are extending inward in the rectangular mounting region Sb where the IC 3   b  is mounted. These wiring patterns  565   b  and  566   b  are extending as far as an interval between the first to third mounting terminals  31   b  to  33   b  and the fourth to sixth mounting terminals  34   b  to  36   b  that are arranged in two rows in the rectangular mounting region Sb in which the IC 3   b  is mounted. 
     The sixth wiring pattern  566   b , in particular, is extending so as to exactly overlap with a rectangular region of projection where a temperature sensor  301   b  embedded in the IC 3   b  is projected in the mounting region Sb. 
     In the earlier embodiment, the second and fifth electrode connectors  542   a  and  545   a  and the second and fifth terminal junctions  532   a  and  535   a  of the second and fifth electrodes  522   a  and  525   a  for mounting purpose are spaced apart at an interval as illustrated in  FIG. 11 , and the these electrode connectors and terminal junctions are electrically interconnected with the fifth and sixth wiring patterns  565  and  566 , as illustrated in  FIG. 11 . 
     In this embodiment, the second and fifth electrode connectors  542   b  and  545   b  and the second and fifth terminal junctions  532   b  and  535   b  of the second and fifth electrodes  522   b  and  525   b  for mounting purpose are disposed in proximity, and these electrode connectors and terminal junctions are electrically interconnected. The fifth and sixth wiring patterns  565   b  and  566   b  are thus not used to electrically interconnect the second and fifth terminal junctions  532   b  and  535   b  and the second fifth electrode connectors  542   b  and  545   b . Instead, these wiring patterns solely function as heat conductors. 
     In the second electrode  522   b  for mounting purpose having the fifth wiring pattern  565   b  and the fifth electrode  525   b  having the sixth wiring pattern  566   b  according to this embodiment, their patterns are formed to be point-symmetric about a central position O of the mounting region Sb rectangular in plan view, similarly to the earlier embodiment. 
     The fifth and sixth wiring patterns  565   b  and  566   b  in this embodiment are respectively connected to the driving electrodes  46  and  45  of the crystal vibration plate  4 , similarly to the earlier embodiment. When heat is radiated from the heated IC 3   b  at higher temperatures than the crystal vibrator  2  and the wiring patterns  565   b  and  566   b  are thereby heated, therefore, heat radiated from the heated wiring patterns  565   b  and  566   b  is conducted to and heat the driving electrodes  46  and  45  of the crystal vibration plate  4 . 
     Therefore, the heated IC 3   b  radiates heat, cooling down to lower temperature degrees, while the crystal vibrator is heated to higher temperature degrees by heat conducted from the fifth and sixth wiring patterns  565   b  and  566   b  heated by the heat radiated from the IC 3   b . This may effectively control possible temperature differences between the IC 3   b  and the crystal vibrator, allowing the state of thermal equilibrium to be reached between these devices. 
     Any difference between the temperature of the crystal oscillator  2  and the temperature detected by the temperature sensor  301   b  of the IC 3   b  may possibly invite frequency variations. Such an unfavorable event, however, may be effectively controlled, and accurate temperature compensation may be thus successfully performed. 
     Third Embodiment 
       FIG. 13  is a schematic structural view of a temperature-compensated crystal oscillator according to yet another embodiment of the present invention. This drawing is illustrated correspondingly to  FIG. 1 .  FIG. 14  is a schematic plan view illustrating the front-surface side of a first sealing member  5   c  in a crystal vibrator  2   c  of a temperature-compensated crystal oscillator  1   c  shown in  FIG. 13 . This drawing is illustrated correspondingly to  FIG. 4 . In these drawings, the same reference signs as in the first embodiment or corresponding reference signs are appended to the same structural elements as described in the first embodiment or corresponding structural elements. 
     In this embodiment, any technical aspects but the electrode patterns on the front surface of the first sealing member  5   c  and an IC 3   c , i.e., the back-surface side of the first sealing member  5   c , the crystal vibration plate  4  and the second sealing member  6 , are substantially the same as described in the first embodiment illustrated in  FIGS. 2, 3 and 5 to 7 . These like components and features, therefore, will not be described again in this embodiment. 
     On the front surface of the first sealing member  5   c  are formed first to sixth electrodes  521   c  to  526   c  to which first to sixth mounting terminals  31   c  to  36   c  of the IC 3   c  are connectable, as illustrated in  FIG. 14 . 
     In a rectangular mounting region Sc defined with a virtual line where the IC 3   c  is mounted, the first to sixth electrodes  521   c  to  526   c  for mounting purpose have first to sixth terminal junctions  531   c  to  536   c  including electrode pads (not illustrated in the drawings) to which the mounting terminals  31   c  to  36   c  of the IC 3   c  are connectable. The first to sixth electrodes  521   c  to  526   c  for mounting purpose further have first to sixth electrode connectors  541   c  to  546   c  electrically connectable to the through electrodes,  504 ,  505 ,  502 ,  503 ,  506  and  501 . These electrode connectors  541   c  to  546   c  are extending from the first to sixth terminal junctions  531   c  to  536   c  in the mounting region Sc toward the outside of the mounting region Sc. 
     At substantially middle positions in the rectangular region Sc close to its short sides are formed junction patterns  551  and  552  extending along the short sides. 
     As illustrated in  FIG. 14 , the first to fourth through electrodes  501  to  504  of the first sealing member  5   c  are electrically connected, respectively, to the electrode connectors  546   c ,  543   c ,  544   c  and  541   c  of the sixth, third, fourth and first electrodes  526   c ,  523   c ,  524   c  and  521   c  for mounting purpose on the front surface of the first sealing member  5   c . Therefore, the first to fourth terminals  631  to  634  for external connection on the back surface of the second sealing member  6  are electrically connected, respectively, to the electrode connectors  546   c ,  543   c ,  544   c  and  541   c  of the sixth, third, fourth and first electrodes  526   c ,  523   c ,  524   c  and  521   c  for mounting purpose on the front surface of the first sealing member  5   c.    
     Because of the mounting terminals  31  to  36  of the IC 3   c  arranged as illustrated in this embodiment, the sixth electrode connector  546   c  formed around the first through electrode  501  of the six electrode  526   c  for mounting purpose is electrically connected to the sixth terminal junction  536   c  disposed at a distant position via a diagonally extending first wiring pattern  571   c.    
     In the vicinity of the sixth electrode connector  546   c  formed around the first through electrode  501 , the wiring pattern  571   c  has a constricted portion  5711   c  smaller in wiring width than the other portions. In the vicinity of the first electrode connector  541   c  formed around the fourth through electrode  504 , the wiring pattern  574   c  has a constricted portion  5711   c  smaller in wiring width than the other portions. The constricted portions  5711   c  and  5744   c  of the first and fourth wiring patterns  571   c  and  574   c  are so shaped that these wiring patterns  571   c  and  574   c  are extending in a progressively smaller width from the sixth and first terminal junctions  536   c  and  531   c.    
     As for the third and fourth electrodes  523   c  and  524   c  for mounting purpose of the first sealing member  5   c , these electrodes for mounting purpose per se constitute the second and third wiring patterns  572   c  and  573   c  for use in electrical connection between the third and fourth electrode connectors  543   c  and  544   c  formed around the second and third through electrodes  502  and  503  and the third and fourth terminal junctions  533   c  and  534   c  to which the third and fourth mounting terminals  33   c  and  34   c  of the IC 3   c  are joined. 
     At a substantially middle position between the third electrode connector  543   c  and the third terminal junction  533   c , the third electrode  523   c  for mounting purpose serving as the second wiring pattern  572   c  has a constricted portion  5722   c  smaller in wiring width than the other portions. At a substantially middle position between the fourth electrode connector  544   c  and the fourth terminal junction  534   c , the fourth electrode  524   c  for mounting purpose serving as the third wiring pattern  573   c  has a constricted portion  5733   c  smaller in wiring width than the other portions. The constricted portions  5722   c  and  5733   c  of the second and third wiring patterns  572   c  and  573   c  are formed by cutting the wiring patterns  572   c  to  573   c  in part on one side into a thin and long rectangular shape. 
     Among the first to sixth electrodes  521   c  to  526   c  for mounting purpose on the front surface of the first sealing member  6   c , the six, third, fourth and first electrodes  526   c ,  523   c ,  524   c  and  521   c  for mounting purpose, except for the second and fifth electrodes  522   c  and  525   c  for mounting purpose that are paired and connected to the first and second driving electrodes  45  and  46  of the crystal vibration plate  4 , respectively have first to fourth wiring patterns  571   c  to  574   c . The first to fourth wiring patterns  571   c  to  574   c  provide electrical connection between the first to fourth through electrodes  501  to  504  and the sixth, third, fourth and first terminal junctions  536   c ,  533   c ,  534   c  and  531   c  to which the IC 3   c  is joined. These wiring patterns  571   c  to  574   c  respectively have the constricted portions  5711   c ,  5722   c ,  5733   c  and  5744   c  smaller in wiring width than the other portions. The constricted portions  5711   c ,  5722   c ,  5733   c  and  5744   c  may successfully prevent the conduction of heat between the first to fourth through electrodes  501  to  504  and the sixth, third, fourth and first terminal junctions  536   c ,  533   c ,  534   c  and  531   c  to which the sixth, third, fourth and first mounting terminals  36   c ,  33   c ,  34   c  and  31   c  of the IC 3   c  are joined. 
     In this manner, the temperature rise gradient of the IC 3   c  may become moderate when the electronic components; heat source, of the external circuit board mounted with the temperature-compensated crystal oscillator  1   a  are turned on and supplied with electric current, similarly to the first embodiment. Further, the temperature drop gradient of the IC 3   c  may also become moderate when the electronic components of the external circuit board are turned off and no longer supplied with electric current. Thus, possible temperature differences between the IC 3   c  and the crystal vibrator may be effectively controlled, and the state of thermal equilibrium may be quickly reached between these devices. As a result, the frequency drift may be unlikely to occur. 
     The constricted portions of the wiring patterns are not necessarily so shaped as thus far described in the embodiments and may have variously different shapes insofar as they are smaller in width than the other portions. The constricted portion  5711   c  of the first wiring pattern  571   c  illustrated in  FIG. 14 , for instance, may be any one selected from the following examples; a constricted portion  5711   c   1  having a constant width smaller than that of the wiring pattern  571   c  extending from the six terminal junction  536   c  in the vicinity of the sixth electrode connector  546   c  formed around the first through electrode  501 , as illustrated in  FIG. 15A , a constricted portion  5711   c   2  progressively reduced in width from the sixth electrode connector  546   c  formed around the first through electrode  501  toward wiring pattern  571   c , as illustrated in  FIG. 15B , and a constricted portion  5711   c   3  constricted in an arc-like shape from both sides of the wiring pattern  571   c  along its width in the vicinity of the sixth electrode connector  546   c  formed around the first through electrode  501 , as illustrated in  FIG. 15C . 
     In the embodiments described thus far, one wiring pattern has a constricted portion at one position thereof. Instead, one wiring pattern may have constricted portions at two or more positions thereof. 
     In the embodiments described thus far, the IC is mounted to the first sealing member on the front-surface side of the crystal vibrator. Instead, the IC may be mounted to the second sealing member  6  on the back-surface side of the crystal vibrator. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  1   a ,  1   c  temperature-compensated piezoelectric oscillator 
           2 ,  2   a ,  2   c  crystal vibrator 
           3 ,  3   a ,  3   c  IC (integrated circuit element) 
           4  crystal vibration plate 
           5 ,  5   a ,  5   b ,  5   c  first sealing member 
           6  second sealing member 
           7  metal bump (metallic material) 
           8  underfill resin 
           31 - 36 , 31   a - 36   a  first to sixth mounting terminals 
           31   b - 36   b , 31   c - 36   c  first to sixth mounting terminals 
           45 ,  46  first, second driving electrode 
           411 - 415  first to fifth through electrodes 
           501 - 506  first to sixth through electrodes 
           601 - 604  first to fourth through electrodes 
           521 - 526 , 521   a - 526   a  first to sixth electrodes for mounting purpose 
           521   b - 526   b , 521   c - 526   c  first to sixth electrodes for mounting purpose 
           531 - 536 , 531   a - 536   a  first to sixth terminal junctions 
           531   b - 536   b , 531   c - 536   c  first to sixth terminal junctions 
           541 - 546 ,  541   a - 546   a  first to sixth electrode connectors 
           541   b - 546   b , 541   c - 546   c  first to sixth electrode connectors 
           571 - 574 ,  571   a - 574   a  first to fourth wiring patterns 
           571   b - 574   b , 571   c - 574   c  first to fourth wiring patterns 
           565 ,  566 ,  565   b ,  566   b  wiring pattern for driving electrode 
           631 - 634  first to fourth terminals for external connection 
         S, Sa, Sb, Sc mounting region