Abstract:
A quartz crystal device includes: a crystal unit in which a crystal blank is hermetically encapsulated; and a mounting substrate housing an IC chip on which a circuit using the crystal blank is integrated. By joining an external terminal of the crystal unit and a bonding terminal of the mounting substrate, the mounting substrate is joined to the crystal unit to be integrated, and the quartz crystal device is configured. In the quartz crystal device, a crystal monitor terminal electrically connected to the bonding terminal is provided on an outer side surface of the mounting substrate, and even in a state in which the crystal unit and the mounting terminal are integrated, a vibration characteristic of the crystal blank is measurable by using the crystal monitor terminal.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a quartz crystal device having a configuration in which a quartz crystal unit and an IC (integrated circuit) chip including a circuit using the crystal unit are integrated, and particularly relates to a quartz crystal device provided with a monitor electrode for inspecting characteristics of a crystal blank used in the crystal element from outside. 
   2. Description of the Related Art 
   As a typical quartz crystal device in which a quartz crystal unit and an IC chip are integrated, there is a surface-mount oscillator in which a crystal unit and an IC chip on which an oscillating circuit using the crystal unit are integrated. Surface-mount crystal oscillators are widely incorporated especially in portable electronic apparatuses such as portable telephones, for example, as reference sources for frequency and time because of their compactness and light weight. 
   As one type of such a surface-mount crystal oscillator, there is a bonding type surface-mount crystal oscillator in which an IC chip and a quartz crystal blank are respectively housed in separate containers and thereafter, the containers are joined to be integrated, as disclosed in Japanese Patent Laid-Open No. 2004-88533 (JP-A-2004-088533).  FIG. 1A  is a side view showing one example of a configuration of a conventional bonding type surface-mount crystal oscillator.  FIG. 1B  is an assembled sectional view of the crystal oscillator.  FIGS. 2A and 2B  are respectively a top view and a bottom view of a mounting substrate for use in the crystal oscillator.  FIG. 3  is a bottom view of a crystal unit in the crystal oscillator. 
   The illustrated crystal oscillator includes mounting substrate  2  housing IC chip  1 , and crystal unit  3  in which crystal blank  8  is hermetically encapsulated, in which mounting substrate  2  is joined to a bottom surface of crystal unit  3  Mounting substrate  2  is a planar member with a substantially rectangular plane shape, and a recess for housing IC chip  1  is formed on one of principal surfaces of mounting substrate  2 . 
   Mounting substrate  2  is configured by laminated ceramics constituted of planar bottom wall layer  2   a  in a substantially rectangular shape, and frame wall layer  2   b  provided on bottom wall layer  2   a  in a frame shape, and a side wall of the recess of mounting substrate  2  is formed by frame wall layer  2 . At four corner portions on a top surface of frame wall layer  2   b , that is, the four corner portions of an opening end surface surrounding the recess of mounting substrate  2 , bonding terminals  5  for electrically and mechanically joining mounting substrate  2  to the bottom surface of crystal unit  3  are formed. Mounting terminals  4  which are used when the crystal oscillator is surface-mounted on a wiring board are provided at four corner portions of an undersurface illustrated in the drawing of bottom wall layer  2   a , that is, an outer bottom surface of mounting substrate  2 . 
   IC chip  1  has a substantially rectangular shape, in which electronic circuits including at least an oscillating circuit using crystal unit  3  are integrated on a semiconductor substrate. In IC chip  1 , the electronic circuits such as the oscillating circuit are formed on one principal surface of the semiconductor substrate by an ordinary semiconductor device fabricating process, and therefore, of a pair of principal surfaces of the semiconductor substrate, the principal surface on which the electronic circuits are formed will be called a circuit formation surface of the IC chip. A plurality of IC terminals for connecting IC chip  1  to an external circuit are also formed on the circuit formation surface. The IC terminals include a power supply terminal, a ground terminal, an oscillation output terminal, an AFC (automatic frequency control) terminal, a pair of crystal connection terminals for connecting to the crystal oscillator, and the like. 
   Circuit terminals  11  are provided on a bottom surface of the recess of mounting substrate  2 , that is, an exposure surface of bottom wall layer  2   a  by the recess to correspond to the IC terminals. The circuit terminals corresponding to the IC terminals, which are the power supply terminal, the ground terminal, the oscillation output terminal and the AFC terminal, are electrically connected to mounting terminals  4  respectively through conductive paths (not shown) formed in mounting substrate  2 . The circuit terminals corresponding to a pair of crystal connection terminals of IC chip  2  are electrically connected to bonding terminals  5 (X) at both ends of one diagonal line of mounting substrate  2 , for example, through conductive paths (not shown). Remaining two bonding terminals  5 (GND) are electrically connected to ground terminals  4 (GND) out of mounting terminals  4  via through-holes provided in mounting substrate  2 , for example. 
   IC chip  1  is fixed to the inner bottom surface of the recess of mounting substrate  2  by causing the circuit formation surface to face the inner bottom surface of the recess of mounting substrate  2 , and electrically and mechanically connecting the IC terminals to circuit terminals  11  by ultrasonic thermo-compression bonding using bumps  6 . In order to protect the circuit formation surface of IC chip  1 , protection resin layer  16  is provided in the recess of mounting substrate  2  as so-called underfill so as to bury a space between the inner bottom surface of the recess and the circuit formation surface. 
   Meanwhile, crystal unit  3  is such that crystal blank  8  is hermetically encapsulated in a recess of container body  7  by housing crystal blank  8  in container body  7 , and joining metal cover  9  to an opening end surface surrounding the recess. Container body  7  is constituted of laminated ceramics having the recess. In the illustrated one, metal cover  9  is joined to a metal thick film or metal ring  15  provided at the opening end surface by seam welding or beam welding. External terminals  10  corresponding to bonding terminals  5  of mounting substrate  2  are provided at four corner portions of an outer bottom surface of container body  7 . A pair of crystal holding terminals  12  for holding crystal blank  8  are provided on an inner bottom surface of the recess of container body  7 . 
   Crystal blank  8  is, for example, a substantially rectangular AT-cut quartz crystal blank, in which excitation electrodes (not shown) are respectively provided on both of its principal surfaces, and from the excitation electrodes, lead electrodes (not shown) are extended to both sides of one end portion of crystal blank  8 . By fixing both the sides of the one end portion of crystal blank  8  where the lead electrodes are extended with conductive adhesive  13  or the like to crystal holding terminals  12 , crystal blank  8  is electrically and mechanically connected to crystal holding terminals  12 , and held in the recess of container body  7 . 
   In container body  7 , a pair of crystal holding terminals  12  are electrically connected to a pair of external terminals  10 (X) on one diagonal line in the outer bottom surface of container body  7  through conductive paths (not shown) formed in container body  7 . External terminals  10 (GND) on the other diagonal line in the outer bottom surface are electrically connected to metal cover  9  through via holes provided in container body  7 . 
   By connecting bonding terminals  5  of mounting substrate  2  to external terminals  10  of crystal unit  3  by using solder or the like, mounting substrate  2  and crystal unit  3  are electrically and mechanically connected, and are completed as a surface-mounting crystal oscillator. At this time, crystal holding terminals  12  in crystal unit  3  are electrically connected to the IC terminals through external terminals  10 (X), bonding terminals  5 (X) and circuit terminals  11 , and therefore, crystal blank  8  is electrically connected to the oscillating circuit in IC chip  1 . Metal cover  9  is also electrically connected to ground terminal  4 (GND) of the mounting terminals. 
   Such a bonding type surface-mount crystal oscillator is ultimately assembled by independently forming mounting substrate  2  loaded with IC chip  1  and crystal unit  3 , and thereafter, joining both of them. On this occasion, before mounting substrate  2  is joined to the outer bottom surface of crystal unit  3 , probes of a measuring apparatus are caused to abut on a pair of external terminals  10 (X), which are formed on the outer bottom surface of container body  7  of crystal unit  3  and electrically connected to crystal blank  8 , to measure a vibration characteristic and the like of crystal blank  8 , and whether crystal unit  3  is good or not is determined. As the vibration characteristic, crystal impedance (CI) is generally measured. Here, when it is determined as a defective, crystal unit  3  is removed from the manufacturing process, and mounting substrate  2  is joined to only good crystal unit  3 . Thereby, an expensive IC chip is not wasted, and productivity can be enhanced. Further, external terminals  10 (X) are formed within the same plane, and probes can be caused to abut on a pair of external terminals  10 (X) form one direction. Therefore, the operation efficiency of measurement of the vibration characteristic becomes high. 
   As another type of a surface-mount crystal oscillator, there is a so-called. two-chamber type in which by using a container body with recesses formed respectively on both principal surfaces, a crystal blank is hermetically encapsulated in the recess of one principal surface to configure a crystal unit, and an IC chip is accommodated in the recess on the other principal surface. A two-chamber type surface-mount crystal oscillator is also called an H-shaped surface-mount crystal oscillator since a container body in which the sectional shape in a central portion is in a H-shape is used.  FIG. 4A  is a side view of such a two-chamber type surface-mount crystal oscillator.  FIG. 4B  is a sectional view of it.  FIG. 5  is a bottom view of the container body with an IC chip removed. In these drawings, the same components as those in  FIGS. 1A ,  1 B,  2 A,  2 B and  3  are assigned with the same reference numerals, and the redundant description of them will be omitted or simplified. 
   Container body  21  has a flat outer shape in a substantially rectangular parallelepiped shape which looks like a rectangle having short sides and long sides seen from above when mounted on a wiring board, and are provided with recesses on its top surface and undersurface respectively. As a result, container body  21  has an H-shaped sectional shape. Container body  21  is constituted of laminated ceramics having planar central layer  21   a  in a substantially rectangular shape, and upper and lower frame layers  21   b  and  21   c  respectively having rectangular openings. First recess  20   a  at an upper side illustrated in the drawing is formed by central layer  21   a  and frame layer  21   b , and quartz crystal blank  8  which functions as a crystal unit is encapsulated in first recess  20   a . Further, second recess  20   b  at a lower side illustrated in the drawing is formed by central layer  21   a  and frame layer  21   c , and IC chip  1  is housed in second recess  20   b.    
   A pair of crystal holding terminals  12  are provided on an inner bottom surface of first recess  20   a , that is, a surface of a front side of central layer  21   a , and crystal blank  8  is fixed and held in first recess  20   a  by fixing lead electrodes to crystal holding terminals  12  with, for example, conductive adhesive  13  or the like at the positions where the pair of lead electrodes are led out, as in the case shown in  FIGS. 1A and 1B . After fixing crystal blank  8 , in the opening end surface of first recess  20   a  of container body  21 , metal cover  9  is joined to metal ring  15  provided on a top surface of frame layer  21   b  by seam welding or the like, whereby crystal blank  8  is hermetically encapsulated in first recess  20   a    
   In container body  21 , mounting terminals  4  which are used when the crystal oscillator is surface-mounted on a wiring board are respectively formed at four corner portions of the opening end surface of frame layer  21   c  forming second recess  20   b . Further, on an inner bottom surface of second recess  20   b , that is, a back surface of central layer  21   a , a plurality of circuit terminals  11  are disposed to be along both long sides of central layer  21   a  as shown in  FIG. 5 . As in the above-described case, circuit terminals  11  are provided to correspond to IC terminals provided on IC chip  1 . In the illustrated example, four circuit terminals  11  are provided in a line along each long side. Four of circuit terminals  11  correspond to, for example, a power source terminal, a ground terminal, an oscillation output terminal, and AFC terminal of the IC terminals, and are electrically connected to corresponding mounting terminals  4  by conductive paths (not shown) formed in central layer  21   a . Further, two of remaining circuit terminals  11  are crystal circuit terminals  11   a  electrically connected to crystal blank  8 . Crystal circuit terminals  11   a  are electrically connected to crystal holding terminals  12  provided on the inner bottom surface of first recess  20   a  through conductive paths (not shown) such as via holes provided in central layer  21   a . Further, a pair of crystal inspection terminals X 1 , X 2  are provided on the back surface of central layer  21   a . Crystal inspection terminals X 1 , X 2  are electrically connected to crystal circuit terminals  11   a  by a conductive pattern provided on the back surface of central layer  21   a . Accordingly, crystal inspection terminals X 1 , X 2  are electrically connected to crystal blank  8 . 
   As IC chip  1 , the one as described above is used. IC chip  1  is fixed to the bottom surface of second recess  20   b  by joining the IC terminals to circuit terminals  11 ,  11   a  provided on the bottom surface of second recess  20   b  by ultrasonic thermo-compression bonding using bumps  6  by the method of so-called flip chip bonding. 
   When such a two-chamber type surface-mount crystal oscillator is manufactured, first, a crystal unit is configured by hermetically encapsulating crystal blank  8  in first recess  20   a , and thereafter, probes for measurement are caused to abut on crystal inspection terminals X 1 , X 2  which are provided on the bottom surface of second recess  20   b , that is, the back surface of central layer  21   a , whereby the vibration characteristic or the like of crystal blank  8  as a crystal unit is measured. At this time, the probes can be caused to abut on a pair of crystal inspection terminals X 1 , X 2  from one direction, and operation efficiency of measurement of the vibration characteristic or the like becomes high. The crystal unit which has abnormality in the vibration characteristic or the like is discarded as a defective, and for the one which is determined as good, IC chip  1  is subsequently mounted on the bottom surface of second recess  20   b . Protective resin layer  16  as underfill for protecting a circuit formation surface of IC chip  1  is further provided, and thereby, a crystal oscillator is completed. Japanese Patent Laid-Open No. 2000-49560 (JP-A-2000-49560), for example, describes disposing crystal inspection terminals on the bottom surface of the recess where the IC chip is to be mounted in the container body, and fixing the IC chip to the bottom surface of the recess after measurement of the oscillation characteristic or the like of the crystal blank in a two-chamber type crystal oscillator. 
   As a surface-mount crystal oscillator, there is a one-chamber type crystal oscillator in which by using a container body having one recess with a step portion formed on an inner wall, an IC chip is fixed to an inner bottom surface of the recess, and both sides of one end portion of a crystal blank where lead electrodes are extended are fixed to the step portion, whereby the crystal blank is disposed above the IC chip. In the one-chamber type crystal oscillator, the crystal blank is fixed after the IC chip is mounted on the bottom surface of the recess. Therefore, the IC chip cannot be mounted after measurement of the vibration characteristic of the crystal blank. The vibration characteristic is measured after the IC chip is mounted and the crystal blank is fixed. 
   Japanese Patent Laid-Open No. 2003-298000 (JP-A-2003-298000) discloses to form the terminals to be used for measurement of the vibration characteristic of a crystal blank, that is, the crystal inspection terminals, on an outer surface of the container body in a one-chamber type crystal oscillator. 
   In the above described bonding type surface-mount crystal oscillator, after the mounting substrate is joined to the crystal unit, external terminals  10 (X) electrically connected to crystal blank  8  are not exposed to an outside, and therefore, the vibration characteristic of crystal blank  8  cannot be measured individually. Similarly, in the two-chamber type surface-mount crystal oscillator, after the IC chip is mounted, crystal inspection terminals X 1 , X 2  are hidden by the IC chip, and therefore, the vibration characteristic of crystal blank  8  cannot be individually measured. However, in order to enhance reliability of the crystal oscillator and respond to request for high functionality, it is required to be able to measure the vibration characteristic of crystal blank  8  even after mounting substrate  2  loaded with IC chip  1  is joined to the bottom surface of crystal unit  3  in the case of a bonding type, or even after IC chip  1  is mounted on the bottom surface of the recess of container body  21  in the case of two-chamber type. More specifically, it is required to be able to measure the vibration characteristic of the crystal blank without passing through the IC chip when whether a product is good or bad is finally determined before shipment after completion of a crystal oscillator, and when failure analysis is performed for searching the cause of a trouble when the trouble occurs during use of a crystal oscillator. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a quartz crystal device which does not impair operation efficiency of measurement of the vibration characteristic of a crystal blank in a manufacture process and is capable of measuring the vibration characteristic of the crystal blank even after being assembled. 
   The object of the present invention is attained by a quartz crystal device including a crystal monitor terminal electrically connected to a crystal blank on an outer side surface separately from an external terminal or a crystal inspection terminal used for measuring a vibration characteristic of the crystal blank in the manufacturing process. 
   A quartz crystal device of the present invention configured as a bonding type is characterized in that the device includes: a crystal unit having a container in which a crystal blank is hermetically encapsulated, and including an external terminal electrically connected to the crystal blank, the external terminal being provided on an outer bottom surface of the container; a mounting substrate including a bonding terminal on one principal surface and a mounting terminal on the other principal surface, and housing an IC chip on which a circuit using the crystal blank is integrated, the bonding terminal corresponding to the external terminal; and a crystal monitor terminal provided on an outer side surface of the mounting substrate and electrically connected to the bonding terminal. The device is further characterize in that, by joining the external terminal and the bonding terminal, the mounting substrate is joined to the crystal unit to be integrated with the crystal unit, and even in a state in which the crystal unit and the mounting terminal are integrated, a vibration characteristic of the crystal blank is measurable by using the crystal monitor terminal. 
   In this bonding type quartz crystal device, the crystal monitor terminal may be formed in a concave portion formed on the outer side surface of the mounting substrate. Further, the mounting substrate is configured by laminated ceramics configured by laminating ceramic sheets in a plurality of layers, and the crystal monitor terminal may be formed on a side surface of each ceramic sheet except for a layer which is the closest to the second principal surface side of the mounting substrate. Furthermore, the crystal monitor terminal may extensively exist on an outer side surface of the crystal unit. 
   According to these bonding type configurations, the vibration characteristic of the crystal blank can be directly measured by using the crystal monitor terminal provided on the outer side surface of the mounting substrate or the container body even after the mounting substrate housing the IC chip is joined to the crystal unit. 
   A quartz crystal device of the present invention configured as a two-chamber type is characterized in that the device includes: a container body having a first recess formed on one principal surface and a second recess formed on the other principal surface; a crystal blank hermetically encapsulated in the first recess; an IC chip which is housed in the second recess by being fixed to a bottom surface of the second recess, and on which a circuit using the crystal blank is integrated; a crystal inspection terminal provided at a position covered with the IC chip in the bottom surface of the second recess, and electrically connected to the crystal blank; and a crystal monitor terminal provided on an outer side surface of the container body, and electrically connected to the crystal blank. The device is further characterized in that even in a state in which the IC chip is fixed to the bottom surface of the second recess, a vibration characteristic of the crystal blank is measurable by using the crystal monitor terminal. 
   In this two-chamber type quartz crystal device, the crystal monitor terminal may be formed in a concave portion formed on the outer side surface of the container body, and the container body may be configured by laminated ceramics configured by laminating ceramic sheets in a plurality of layers. 
   According to these two-chamber type configurations, the vibration characteristic of the crystal blank can be directly measured by using the crystal monitor terminal provided on the outer side surface of the mounting substrate or the container body even after the IC chip is fixed to the bottom surface of the recess of the container body. 
   By applying the present invention, the vibration characteristic of the crystal blanks can be measured without passing through the IC chips, for example, when whether the products are good or not is determined before shipment after completion of the crystal oscillators, or when failure analysis for searching the cause of a trouble is performed when the trouble occurs during use of the crystal oscillators. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A and 1B  are a side view and an assembled sectional view, respectively, showing one example of a configuration of a conventional bonding type surface-mount crystal oscillator; 
       FIG. 2A  is a top view of a mounting substrate in the crystal oscillator shown in  FIGS. 1A and 1B ; 
       FIG. 2B  is a bottom view of the mounting substrate in the crystal oscillator shown in  FIGS. 1A and 1B ; 
       FIG. 3  is a bottom view of a crystal unit in the crystal oscillator shown in  FIGS. 1A and 1B ; 
       FIGS. 4A and 4B  are a side view and an assembled sectional view, respectively, showing one example of a configuration of a conventional two-chamber type surface-mount crystal oscillator; 
       FIG. 5  is a bottom view of a container body in the crystal oscillator shown in  FIGS. 4A and 4B  with an IC chip removed; 
       FIGS. 6A and 6B  are a side view and an assembled sectional view, respectively, showing a configuration of a surface-mount crystal oscillator according to a first embodiment of the present invention; 
       FIGS. 7A and 7B  are a top view and a bottom view of a mounting substrate in the crystal oscillator of the first embodiment, respectively; 
       FIG. 8  is a side view showing a configuration of a surface-mount crystal oscillator according to a second embodiment of the present invention; 
       FIG. 9  is a side view showing a configuration of a surface-mount crystal oscillator according to a third embodiment of the present invention; and 
       FIG. 10  is a bottom view of a container body in the crystal oscillator of the third embodiment with an IC chip removed. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
   In  FIGS. 6A ,  6 B,  7 A and  7 B showing a quartz crystal device according to a first embodiment of the present invention, the same components as those in  FIGS. 1A ,  1 B,  2 A,  2 B,  3 ,  4 A,  4 B and  5  are assigned with the same reference numerals, and the redundant description of them will be omitted or simplified. 
   A surface-mount crystal oscillator of the first embodiment is similar to the conventional bonding type surface-mount crystal oscillator shown in  FIGS. 1A ,  1 B,  2 A and  2 B, but differs from the conventional one in the point that crystal monitor terminals  22  are provided on outer side surfaces of mounting substrate  2 . 
   Of four outer side surfaces of mounting substrate  2  having a substantially rectangular planar shape, in central portions of a pair of outer side surfaces opposed to each other along long sides of mounting substrate  2 , concave portions  23  each with a section in the shape of a pan bottom are formed to connect a bottom surface and a top surface of mounting substrate  2 . Each of concave portions  23  is formed in a region interposed between mounting terminals  4  which are provided respectively at both end portions of the side of the bottom surface, when seen from the bottom surface side of mounting substrate  2 , as shown in  FIG. 7B . In such concave portion  23 , at a position corresponding to a side surface of frame wall layer  2   b , crystal monitor terminal  22  is formed. Crystal monitor terminal  22  is not formed at the position corresponding to a side surface of bottom wall layer  2   a . This is because if crystal monitor terminal  22  is formed at a position corresponding to the side surface of bottom wall layer  2   a , there occurs the fear of crystal monitor terminal  22  and a circuit pattern on a wiring board being electrically contact each other unexpectedly when the crystal oscillator is mounted on the wiring board. When bottom wall layer  2   a  itself is also configured by ceramic sheets in a plurality of layers in mounting substrate  2  configured by laminated ceramics, crystal monitor terminal  22  may be also formed on a side surface of a ceramic sheet of each layer except for the ceramic sheet to be the lowest bottom surface of mounting substrate  2 , so that in concave portion  23 , crystal monitor terminal  22  is formed to extend to the side surface of bottom wall layer  2   a  from the side surface of frame wall layer  2   b , and the electrode area of crystal monitor terminal  22  becomes large. When the problem of the fear of electrical contact with the circuit pattern on a wiring board or the like does not occur, crystal monitor terminal  22  may be formed on the side surface of the lowermost layer portion of bottom wall layer  2   a.    
   Such concave portion  23  and crystal monitor terminal  22  are formed by performing through-hole machining and through-hole plating processing to the machined surface when mounting substrate  2  is formed by laminating and firing ceramic green sheets corresponding to bottom wall layer  2  and frame wall layer  2   b.    
   Crystal monitor terminals  22  formed on a pair of outer side surfaces which opposed to each other of mounting substrate  2  are electrically connected to a pair of circuit terminals  11   a  corresponding to crystal connection terminals of IC chip  1  out of circuit terminals  11  formed on an inner bottom surface of a recess of mounting substrate  2 , that is, a top surface of bottom wall layer  2   a , through conductive paths  24  as shown by the broken lines in  FIG. 7B . Conductive paths are formed on a lamination plane between frame wall layer  2   b  and bottom wall layer  2   a . Circuit terminals  11   a  are also connected to bonding terminals  5 (X) formed at corner portions of a top surface of frame wall layer  2   b , and as a result, a pair of crystal monitor terminals  22  are electrically connected to a pair of bonding terminals  5 (X). 
   Such a bonding type surface-mount crystal oscillator of the first embodiment is assembled by independently forming mounting substrate  2  loaded with IC chip  1  and crystal unit  3 , and thereafter, joining both of them. On this occasion, before mounting substrate  2  is joined to the bottom surface of crystal unit  3 , probes of a measuring apparatus are caused to abut on a pair of external terminals  10 (X) formed on an outer bottom surface of container body  7  of crystal unit  3 , a vibration characteristic of crystal blank  8  is measured, whether the crystal unit is good or not is determined, and thereafter, mounting substrate  2  is joined to only good crystal unit  3  to complete a crystal oscillator. 
   In the crystal oscillator, access cannot be got from an outside to external terminals  10 (X) which are electrically connected to crystal blank  8 , after completion of the crystal oscillator, but instead, crystal monitor terminals  22  are electrically connected directly to crystal blank  8 . Therefore, by causing the probes for measurement to abut on crystal monitor terminals  22 , the vibration characteristic of crystal blank  8  can be measured. Accordingly, in the surface-mount crystal oscillator, when whether the product is good or not is finally determined before shipment, and when failure analysis for search of the cause of a trouble is performed when the trouble occurs during use of the crystal oscillator, the vibration characteristic of the crystal blank can be measured without passing through the IC chip. 
   Second Embodiment 
   Next, a surface-mount crystal oscillator which is a quartz crystal device according to a second embodiment of the present invention will be described. In the above described first embodiment, in the bonding type surface-mount crystal oscillator, crystal monitor terminals  22  are provided at only the outer side surfaces of mounting substrate  2  which houses IC chip  1 , but in order to enlarge an area of crystal monitor terminals  22  to make it easy for probes to abut on them, crystal monitor terminals  22  can be also formed on the outer side surfaces of crystal unit  3 . The crystal oscillator of the second embodiment shown in  FIG. 8  is such that crystal monitor terminals  22  are also disposed at the outer side surfaces of crystal unit  3  in the crystal oscillator of the first embodiment. In  FIG. 8 , the same components as those in  FIGS. 6A ,  6 B,  7 A and  7 B are assigned with the same reference numerals, and the redundant description of them will be omitted or simplified. 
   In the second embodiment, concave portions  23  are also formed on the outer side surfaces of crystal unit  3  so that concave portions  23  on the outer side surfaces of mounting substrate  2  directly extend, and crystal monitor terminals  22  are also provided in concave portions  23  in the regions at the outer side surfaces of crystal unit  3 . Crystal monitor terminals  22  in crystal unit  3  are electrically connected to external terminals  5 (X) of crystal unit  3  through conductive paths (not shown) formed in a bottom surface of crystal unit  3 , for example. Container body  7  of crystal unit  3  is formed of laminated ceramics, and concave portions  23  are formed to connect a top surface and a bottom surface of container body  7 . In order to avoid electrical contact with metal cover  9 , crystal monitor terminals  22  are formed on side surfaces of the respective layers except for the uppermost layer out of ceramic sheets in a plurality of layers configuring container body  7  in concave portions  23  of container body  7 . Here, the uppermost layer of the ceramic sheets means the layer which is the closest to the top surface of container body  7 . Concave portion  23  and crystal monitor terminal  22  are formed by performing through-hole machining and through-hole plating when the ceramic green sheets are laminated and fired to form container body  7  as in the case of mounting substrate  2 . 
   In the second embodiment, before mounting substrate  2  loaded with IC chip  1  is joined to the bottom surface of crystal unit  3 , probes of a measuring apparatus is caused to abut on a pair of external terminals  10 (X) formed on an outer bottom surface of container body  7  of crystal unit  3 , the vibration characteristic or the like of crystal blank  8  is measured, whether the crystal unit is good or not is determined, and thereafter, mounting substrate  2  is joined to only good crystal unit  3  to complete the crystal oscillator. On this occasion, since crystal monitor terminals  22  are also already formed on the outer side surface of crystal unit  3 , the vibration characteristic of crystal blank  8  can be measured by using the crystal monitor terminals, but the probes have to be caused to abut on a pair of crystal monitor terminals  22  in such a manner that the probes nip them form the two opposite directions, and therefore, operability becomes worse as compared with the case in which probes are caused to abut on a pair of external terminals  10 (X) from one direction 
   The surface-mount crystal oscillator of the second embodiment has the advantage of being capable of measuring the vibration characteristic of a crystal blank without passing through the IC chip, when whether the product is good or not is finally determined before shipment, or failure analysis for search of the cause of a trouble is performed when the trouble occurs during use of the crystal oscillator, as in the crystal oscillator of the first embodiment. Further, the crystal oscillator of the second embodiment has the advantage of easily causing probes to abut on crystal monitor terminals  22  as compared with the one of the first embodiment since crystal monitor terminals  22  are also formed on the outer side surfaces of crystal unit  3 . When mounting substrate  2  is joined to crystal unit  3 , a space of about 50 μm is formed between both of them, and a slit having a width of about the same value as this is formed in each of crystal monitor terminals  22 , but the slit of this width is sufficiently small as compared with the dimension of the tip end of the probe, and therefore, does not become a trouble for measuring the vibration characteristic. 
   Third Embodiment 
   Next, a surface-mount crystal oscillator which is a quartz crystal device according to a third embodiment of the present invention will be described. In the first and second embodiments, the present invention is applied to the bonding type surface-mount crystal oscillator, but the present invention can be also applied to a two-chamber type surface-mount crystal oscillator. The third embodiment is an example of application of the present invention to a two-chamber type surface-mount crystal oscillator.  FIG. 9  is a side view showing a surface-mount crystal oscillator of the third embodiment.  FIG. 10  is a bottom view of a container body in this crystal oscillator with an IC chip removed. In these drawings, the same components as those shown in  FIGS. 4A ,  4 B and  5  are assigned with the same reference numerals, and the redundant description of them will be omitted or simplified. 
   The surface-mount crystal oscillator of the third embodiment is similar to the conventional two-chamber type surface-mount crystal oscillator shown in  FIGS. 4A ,  4 B and  5 , but differs from the conventional one in the point that crystal monitor terminals  22  are provided on an outer side surface of container body  21 . 
   As the one shown in  FIGS. 4A ,  4 B and  5 , container body  21  with a substantially rectangular planar shape is configured by laminated ceramics in which frame layers  21   b  and  21   c  are respectively laminated on a top surface and an undersurface of central layer  21   a . Of four outer side surfaces of container body  21 , in central portions of a pair of outer side surfaces opposed to each other along long sides of container body  21 , concave portions  23  each with a section in the shape of a pan bottom are respectively formed to connect an upper end surface and a bottom surface of container body  21 . Crystal monitor terminals  22  are provided in concave portions  23  as in the first and second embodiments. Each crystal monitor terminal  22  is formed at a position corresponding to a side surface of a ceramic sheet of each layer except for the ceramic sheets corresponding to the lowest bottom surface and the uppermost surface in container body  21  configured by laminating and firing the ceramic green sheets in a plurality of layers. The ceramic sheet corresponding to the lowest bottom surface means the ceramic sheet which is in contact with a wiring board. Crystal monitor terminals  22  are electrically connected to crystal circuit terminals  11   a  through conductive paths  24  formed in a lamination plane between central layer  21   a  and frame layer  21   c . In the drawing, conductive paths  24  are shown by the broken lines. Crystal circuit terminals  11   a  are also electrically connected to crystal blank  8 , and therefore, crystal monitor terminals  22  are electrically connected to crystal blank  8 . 
   When the two-chamber type surface-mount crystal oscillator of this embodiment is manufactured, a crystal unit is configured by hermetically encapsulating crystal blank  8  in first recess  20   a , after which, probes for measurement are caused to abut on a pair of crystal inspection terminals X 1 , X 2  provided on the bottom surface of second recess  20   b , whereby, the vibration characteristic or the like of crystal blank  8  as a crystal unit is measured, and whether the crystal unit is good or not is determined. For the one which is determined as good, IC chip  1  is mounted on the bottom surface of second recess  20   b  next, and thereby, the crystal oscillator is completed. When the vibration characteristic of crystal blank  8  needs to be measured after the crystal oscillator is completed, the vibration characteristic can be directly measured by causing probes to abut on crystal monitor terminals  22  instead of crystal inspection terminals X 1 , X 2 .