Abstract:
Disclosed is a piezoelectric component ( 1 ) comprising a piezoelectric transducer ( 10 ) wherein a pair of electrodes ( 20   a,    20   b ) are formed on both major surfaces of a piezoelectric substrate ( 11 ), a pair of frame members ( 30   a,    30   b ) fitted to both major surfaces of the piezoelectric transducer ( 10 ), a pair of sealing substrates ( 40   a,    40   b ) composed of a light-transmitting resin material and so fitted as to cover the frame members ( 30   a,    30   b ), opaque coating layers ( 50   a,    50   b ) respectively formed on the sealing substrates ( 40   a,    40   b ), and a pair of input/output terminal electrodes ( 61   a,    61   b ) respectively connected to the electrodes ( 20   a,    20   b ). By having such a constitution, the state of sealed space and sealing widths of the frame members ( 30   a,    30   b ) can be checked by visual examination such as direct visual observation or image recognition, and thus a highly reliable piezoelectric component ( 1 ) can be obtained. In addition, a mark can be made on the coating layers ( 50   a,    50   b ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 11/911,107 (issued as U.S. Pat. No. 7,649,306 on Jan. 19, 2010) which is the U.S. national phase application of PCT/JP2006/308832 filed Apr. 27, 2006 and claims the benefit of Japanese patent application serial number JP2006-087614 filed Mar. 28, 2006 and Japanese patent application number JP2005-129161 filed Apr. 27, 2005, each of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a piezoelectric component which is easily manufactured and is in reliability and relates to a method for manufacturing such a piezoelectric component. 
       BACKGROUND 
       [0003]    In general, microcomputers are used in communication equipment and electronic equipment. In such microcomputers, piezoelectric components including piezoelectric resonator are widely used as clock sources. 
         [0004]    In a known piezoelectric component, vibrating electrodes are formed on both major surfaces of a piezoelectric substrate, and sealed spaces are formed between the vibrating electrodes and sealing electrodes respectively on the major surfaces for allowing vibration of the vibrating electrodes. 
         [0005]    Recently, communication equipment and electronic equipment have been reduced in size and thickness. Consequently, components mounted on these equipments are increasingly required to be reduced in size and thickness. 
       SUMMARY 
       [0006]    According to one aspect of the present invention, a piezoelectric component includes a piezoelectric oscillating element, a pair of frames, a pair of sealing substrates, a pair of input/output terminal electrodes, and ground terminal electrodes. The piezoelectric oscillating element is composed of a pair of electrodes which are disposed on both major surfaces of the piezoelectric substrate. The pair of electrodes at least partially face each other with the piezoelectric substrate therebetween. The pair of frames are arranged on the respective major surfaces of the piezoelectric substrate so as to surround the regions of the pair of electrodes facing each other. The pair of sealing substrates are composed of a light-transmissive resin material arranged so as to cover the respective external surfaces of the pair of frames. The pair of input/output terminal electrodes are respectively connected to the pair of electrodes. The ground terminal electrodes are on the side faces of the piezoelectric substrate. The pair of electrodes comprises vibrating electrodes facing each other with the piezoelectric substrate therebetween, extractor electrodes connecting the vibrating electrodes to the input/output terminal electrodes, and capacitor electrodes protruding from the vibrating electrodes or the extractor electrodes toward the ground terminal electrodes and generating capacitors with the ground terminal electrodes. 
         [0007]    According to another aspect of a present invention, a method of manufacturing the piezoelectric component has three steps. In the first step, a piezoelectric mother substrate provided with electrodes on both major surfaces thereof and having a plurality of element regions which are each separately formed into a piezoelectric oscillating element is prepared. In the second step, lattice bodies composed of a light-transmissive resin material are formed on both major surfaces of the piezoelectric mother substrate, wherein the lattice bodies are divided together with the element regions along the boundaries of the element regions into frames on the respective piezoelectric oscillating elements. In the third step, a plurality of sealed spaces by the piezoelectric mother substrate, the parts of the lattice bodies which become the frames, and a sealing mother substrate composed of a light-transmissive resin material are formed by attaching the sealing mother substrate so as to cover the lattice bodies at one major surface side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an external perspective view schematically illustrating a piezoelectric component according to an embodiment of the present invention. 
           [0009]      FIG. 2  is a longitudinal sectional view schematically illustrating the piezoelectric component according to an embodiment of the present invention. 
           [0010]      FIG. 3  is an exploded perspective view schematically illustrating the piezoelectric component according to an embodiment of the present invention. 
           [0011]      FIG. 4  is a plan view of a piezoelectric substrate used in the piezoelectric component shown in  FIG. 1 . 
           [0012]      FIG. 5  is a cross-sectional view taken along A-A line of the piezoelectric substrate used in the piezoelectric component shown in  FIG. 1 . 
           [0013]      FIG. 6  is an equivalent circuit diagram of the piezoelectric component according to an embodiment of the present invention. 
           [0014]      FIG. 7  is an external perspective view schematically illustrating a piezoelectric component according to an embodiment of the present invention. 
           [0015]      FIG. 8  is a longitudinal sectional view schematically illustrating the piezoelectric component according to an embodiment of the present invention. 
           [0016]      FIG. 9  is an exploded perspective view schematically illustrating the piezoelectric component according to an embodiment of the present invention. 
           [0017]      FIG. 10  is a top view illustrating a capacitor element used in the piezoelectric component according to the embodiment of the present invention. 
           [0018]      FIG. 11  is a bottom view illustrating the capacitor element used in the piezoelectric component according to an embodiment of the present invention. 
           [0019]      FIG. 12  is a plan view schematically illustrating a process of manufacturing a piezoelectric component according to an embodiment of the present invention. 
           [0020]      FIG. 13  is a plan view schematically illustrating another process of manufacturing the piezoelectric component according to an embodiment of the present invention. 
           [0021]      FIG. 14  is a plan view schematically illustrating another process of manufacturing the piezoelectric component according to an embodiment of the present invention. 
           [0022]      FIG. 15  is a plan view schematically illustrating another process of manufacturing the piezoelectric component according to an embodiment of the present invention. 
           [0023]      FIG. 16  is a plan view schematically illustrating another process of manufacturing the piezoelectric component according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  is an external perspective view schematically illustrating a piezoelectric component according to an embodiment of the present invention. In this embodiment,  FIG. 2  is a longitudinal sectional view of the piezoelectric component shown in  FIG. 1 , and  FIG. 3  is an exploded perspective view of the piezoelectric component shown in  FIG. 1 . Also in this embodiment,  FIG. 4  is a plan view of a piezoelectric oscillating element used in the piezoelectric component shown in  FIG. 1 , and  FIG. 5  is a cross-sectional view taken along A-A line. Additionally in this embodiment,  FIG. 6  is an equivalent circuit diagram of the piezoelectric component shown in  FIG. 1 . 
         [0025]    The piezoelectric component  1  has a structure including a piezoelectric oscillating element  10  in which a pair of electrodes  20   a  and  20   b  are formed on both major surfaces of a piezoelectric substrate  11  so as to partially face each other with the piezoelectric substrate  11  therebetween; a pair of frames  30   a  and  30   b  disposed on the respective both major surfaces of the piezoelectric substrate  11  so as to surround the facing area A of the pair of electrodes  20   a  and  20   b;  a pair of sealing substrates  40   a  and  40   b  arranged so as to cover the respective external surfaces of the pair of frames  30   a  and  30   b;  and coating layers  50   a  and  50   b  disposed on the external surfaces of the pair of sealing substrates  40   a  and  40   b.    
         [0026]    The electrode  20   a  is connected to a pair of input/output terminal electrodes  61   a  and  61   b  disposed on the side faces of the piezoelectric component  1 , and the electrode  20   b  is connected to a pair of input/output terminal electrodes  62   a  and  62   b  disposed on the side faces of the piezoelectric component  1 . Furthermore, ground terminal electrodes  63   a  and  63   b  are respectively disposed between the input/output terminal electrodes  61   a  and  62   a  and between  61   b  and  62   b  on the side faces of the piezoelectric component  1 . 
         [0027]    The pair of input/output terminal electrodes  61   a  and  61   b  is collectively represented by reference numeral  61 , the pair of input/output terminal electrodes  62   a  and  62   b  is collectively represented by reference numeral  62 , and the ground terminal electrodes  63   a  and  63   b  are collectively represented by reference numeral  63 . 
         [0028]    The input/output terminal electrodes  61  and  62  and the ground terminal electrodes  63  are disposed on both side faces of the piezoelectric substrate  11 , i.e., the input/output terminal electrodes  61   a  and  62   a  and the ground terminal electrode  63   a  are disposed on one side face and the input/output terminal electrodes  61   b  and  62   b  and the ground terminal electrode  63   b  are disposed on the other side face. 
         [0029]    In addition, external connection electrodes  71 ,  72 , and  73  are disposed on the bottom face of the piezoelectric component  1 . The input/output terminal electrodes  61   a  and  61   b  are connected to the external connection electrode  71 , the input/output terminal electrodes  62   a  and  62   b  are connected to the external connection electrode  72  and the ground terminal electrodes  63   a  and  63   b  are connected to the external connection electrode  73 . 
         [0030]    As shown in  FIGS. 4 and 5 , the electrode  20   a  of the pair of electrodes  20   a  and  20   b  disposed on both major surfaces of the piezoelectric substrate  11  comprises a vibrating electrode  21   a,  an extractor electrode  22   a  for connecting the vibrating electrode  21   a  to the input/output terminal electrodes  61   a  and  61   b,  and a capacitor electrode  23   a  extending from the vibrating electrode  21   a  toward the ground terminal electrode  63   a  to generate a capacitor with the ground terminal electrode  63   a.    
         [0031]    Similarly, the electrode  20   b  comprises a vibrating electrode  21   b,  an extractor electrode  22   b  for connecting the vibrating electrode  21   b  to the input/output terminal electrodes  62   a  and  62   b,  and a capacitor electrode  23   b  extending from the vibrating electrode  21   b  toward the ground terminal electrode  63   b  to generate a capacitor with the ground terminal electrode  63   b.    
         [0032]    The vibrating electrodes  21   a  and  21   b  are disposed so as to partially face each other with the piezoelectric substrate  11  therebetween. Energy is confined between the vibrating electrodes  21   a  and  21   b  by applying an electric field between the vibrating electrodes  21   a  and  21   b,  and thereby thickness vibration is excited (see  FIG. 5 ). As a result, the piezoelectric oscillating element  10  resonates at a certain frequency. 
         [0033]    In addition, a load capacitor C 1  shown in the equivalent circuit diagram of  FIG. 6  is generated between the capacitor electrode  23   a  and the ground terminal electrode  63   a,  and a load capacitor C 2  shown in the equivalent circuit diagram of  FIG. 6  is generated between the capacitor electrode  23   b  and the ground terminal electrode  63   b.    
         [0034]    Consequently, as a whole, a piezoelectric component  1  includes a piezoelectric oscillating element  10  and load capacitors C 1  and C 2 , as shown in  FIG. 6 . 
         [0035]    The characteristic of the piezoelectric component  1  according to this embodiment is that the sealing substrates  40   a  and  40   b  are composed on a light-transmissive resin material. 
         [0036]    Therefore, it can be confirmed by appearance inspection from the outside of the sealing substrates  40   a  and  40   b  during the manufacturing processes whether or not the vibrating electrodes  21   a  and  21   b  are in contact with the frames  30   a  and  30   b,  whether or not sealing widths (indicated by “d” in  FIG. 2 ) formed by the frames  30   a  and  30   b  are sufficient, or whether or not continuous bubbles or the like, which reduce the hermeticity of sealed spaces, are present in the insides of the sealing substrates or in the interfaces between the sealing substrates and the frames. Thereby, a piezoelectric component  1  having high reliability can be obtained. 
         [0037]    The light transmittance of the sealing substrates  40   a  and  40   b  is preferably 25% or more for readily conducting appearance inspection without using a specific light source. The state of sealed spaces can be visually inspected under usual room brightness (about 1500 lux) by adjusting the transmittance to 25% or more. If the light transmittance of the sealing substrates  40   a  and  40   b  is less than 25%, it is less easy to visually inspect the state of sealed spaces. The light transmittance in the present invention is a value that can be measured using a spectrophotometer. Specifically, the light transmittance of sealing substrates  40   a  and  40   b  is determined by irradiating each of the sealing substrates  40   a  and  40   b  with visible light (400 to 800 nm), measuring intensities of the light before and after the transmission through the sealing substrate by a spectrophotometer, and calculating a ratio of the light intensity after the transmission to the intensity before the transmission (light intensity transmitted through a resin substrate/light intensity of a light source). 
         [0038]    Furthermore, the sealing substrates  40   a  and  40   b  can be reduced in thickness by forming them with a resin material, which is good in workability. Thus, a piezoelectric component  1  with a reduced thickness can be obtained. 
         [0039]    In addition, in the piezoelectric component  1  according to this embodiment, the resin material constituting the sealing substrates  40   a  and  40   b  is good in elasticity and toughness. 
         [0040]    Consequently, the sealing substrates  40   a  and  40   b  themselves have high resistance to external forces and thermal and mechanical shocks and simultaneously absorb and relieve external forces and shocks to protect the piezoelectric substrate  11 . 
         [0041]    Thereby, a piezoelectric component  1  having high reliability can be obtained. Materials for the sealing substrates  40   a  and  40   b  will be described in detail below. 
         [0042]    In the piezoelectric component  1  according to this embodiment, frames  30   a  and  30   b  composed of a light-transmissive resin material are preferred. 
         [0043]    In such a case, it can be easily visually inspected from the outsides of the sealing substrates  40   a  and  40   b  whether or not, for example, continuous bubbles, which reduce the hermeticity of sealed spaces S formed by the piezoelectric substrate  11 , the frames  30   a  and  30   b,  and the sealing substrates  40   a  and  40   b,  are present in the insides of the frames  30   a  and  30   b  or in the interfaces between the frames  30   a  and  30   b  and the piezoelectric substrate  11 . Thereby, a piezoelectric component  1  having high reliability can be obtained. Whether or not bubbles are present in the interfaces of the frames  30   a  and  30   b  and the piezoelectric substrate  11  can be easily visually inspected by adjusting the light transmittances of the sealing substrates  40   a  and  40   b  and the frames  30   a  and  30   b  to 50% or more, even if after the sealing substrates  40   a  and  40   b  are formed on the external surfaces of the frames  30   a  and  30   b.  Therefore, in one embodiment it is preferable that the sealing substrates  40   a  and  40   b  and the frames  30   a  and  30   b  each have a light transmittance of 50% or more. 
         [0044]    In addition, in the piezoelectric component  1  according to this embodiment, coating layers  50   a  and  50   b  composed of a light-shielding (opaque) resin material are disposed on the external surfaces of the sealing substrates  40   a  and  40   b.  These coating layers  50   a  and  50   b  are provided with marks (denoted by M in  FIG. 16 ). The “mark” is, for example, the serial number of a piezoelectric component  1  or a trademark identifying the manufacturer. 
         [0045]    If a mark is directly provided to the sealing substrate  40   a  or  40   b,  which is light transmissive, the mark is difficult to be identified. 
         [0046]    Therefore, a piezoelectric component  1  improved in visibility of marks can be obtained by disposing the light-shielding coating layers  50   a  and  50   b  and marking the coating layers  50   a  and  50   b,  compared to a case in which marks are directly provided to the sealing substrates  40   a  and  40   b  composed of a light-transmissive resin material. At the same time, these coating layers  50   a  and  50   b  composed of a light-shielding resin material can protect the sealing substrates  40   a  and  40   b.    
         [0047]    Furthermore, in the piezoelectric component  1  according to this embodiment, as shown in  FIG. 5 , a capacitor C 1  is generated between the capacitor electrode  23   a  and the ground terminal electrode  63   a,  and a capacitor C 2  is generated between the capacitor electrode  23   b  and the ground terminal electrode  63   b.  Thereby, it is not necessary to separately form capacitor elements for generating load capacitors C 1  and C 2 . Therefore, a piezoelectric component  1  containing a piezoelectric oscillating element  10  and load capacitors C 1  and C 2  can be miniaturized. 
         [0048]    As shown in  FIG. 4  which is a plan view of a piezoelectric substrate  11 , the capacitor electrode  23   a  and the capacitor electrode  23   b  are preferably disposed not to face each other with the piezoelectric substrate  11  therebetween, namely, disposed so as to be shifted from each other. 
         [0049]    Thereby, the capacitors C 1  and C 2  can be obtained without significantly damping the thickness vibration generated in the vibrating electrodes  21   a  and  21   b.  This is because, as shown in the cross-sectional view of  FIG. 5 , the capacitors C 1  and C 2  are formed in regions remote from the facing area A of the vibrating electrode  21   a  and the vibrating electrode  21   b , and the largest vibration is at the center of the facing area A and the vibration is decreased with the distance from the center toward the outside. Therefore, even if electric fields are generated by the capacitors C 1  and C 2 , the electric fields rarely affect the thickness vibration in the facing area A. 
         [0050]    Furthermore, since the frames  30   a  and  30   b  composed of an insulative resin are disposed on the piezoelectric substrate  11  between the capacitor electrode  23   a  and the ground terminal electrode  63   a  and between the capacitor electrode  23   b  and the ground terminal electrode  63   b,  respectively, the capacities of the capacitors C 1  and C 2  can be increased. This is because the frames  30   a  and  30   b  have a dielectric constant higher than that of the air. 
         [0051]    Furthermore, the frames  30   a  and  30   b  can block the adhesion of metallic foreign materials. Therefore, even if the distances between the capacitor electrode  23   a  and the ground terminal electrode  63   a  and between the capacitor electrode  23   b  and the ground terminal electrode  63   b  are reduced, electrical short between the electrodes caused by, for example, adhesion of a metallic foreign material can be avoidable. 
         [0052]      FIG. 7  is an external perspective view schematically illustrating a piezoelectric component according to another embodiment of the present invention. 
         [0053]      FIG. 8  is a longitudinal sectional view schematically illustrating the piezoelectric component shown in  FIG. 7 , and  FIG. 9  is an exploded perspective view of the piezoelectric component shown in  FIG. 7 . 
         [0054]      FIGS. 10 and 11  are a top view and a bottom view, respectively, schematically illustrating a capacitor element used in the piezoelectric component shown in  FIG. 7 . 
         [0055]    In this embodiment, only elements different from those of the above-mentioned embodiment will be described. The same elements are referred to by the same reference numerals, and their description is omitted. 
         [0056]    The piezoelectric component  2  according to this embodiment is characterized in that capacitor electrodes  23   a  and  23   b  are not formed on the piezoelectric substrate  11  and, instead, a capacitor element  80  is disposed on the bottom face of a sealing substrate  40   b.    
         [0057]    As shown in  FIGS. 9 ,  10 , and  11 , the capacitor element  80  consists of a dielectric substrate  81 , a pair of hot-side capacitor electrodes  82   a  and  82   b  disposed on the top face of the dielectric substrate  81 , and a ground-side capacitor electrode  83  disposed on the bottom face of the dielectric substrate  81 . 
         [0058]    The hot-side capacitor electrode  82   a  is connected to an extractor electrode  22   a  disposed on one major surface of the piezoelectric substrate  11  and to an external connection electrode  71  disposed on the bottom face of the dielectric substrate  81  via input/output terminal electrodes  61   a  and  61   b,  respectively. The hot-side capacitor electrode  82   b  is connected to an extractor electrode  22   b  disposed on another major surface of the piezoelectric substrate  11  and to an external connection electrode  72  disposed on the bottom face of the dielectric substrate  81  via input/output terminal electrodes  62   a  and  62   b,  respectively. The ground-side capacitor electrode  83  is arranged between the external connection electrodes  71  and  72  on the bottom face of the dielectric substrate  81 . Both ends of the ground-side capacitor electrode  83  are connected to the ground terminal electrodes  63   a  and  63   b,  respectively. The ground-side capacitor electrode  83  also has a function as an external connection electrode. 
         [0059]    As shown in  FIG. 6 , a load capacitor C 1  is formed between the hot-side capacitor electrode  82   a  and the ground-side capacitor electrode  83 , and a load capacitor C 2  is formed between the hot-side capacitor electrode  82   b  and the ground-side capacitor electrode  83 . Consequently, a piezoelectric component  2  containing a piezoelectric oscillating element  10  and the load capacitors C 1  and C 2 , as an equivalent circuit diagram shown in  FIG. 6 , is obtained. 
         [0060]    In the piezoelectric component  2  according to this embodiment, since the hot-side capacitor electrode  82   a  and the ground-side capacitor electrode  83  are disposed so as to face each other with the dielectric substrate  81  therebetween, a capacitor C 1  with a large capacity can be generated between the hot-side capacitor electrode  82   a  and the ground-side capacitor electrode  83 . Similarly, since the hot-side capacitor electrode  82   b  and the ground-side capacitor electrode  83  are disposed so as to face each other with the dielectric substrate  81  therebetween, a capacitor C 2  with a large capacity can be generated between the hot-side capacitor electrode  82   b  and the ground-side capacitor electrode  83 . 
         [0061]    Next, a method for manufacturing the piezoelectric component will be described with reference to the piezoelectric component  1  shown in  FIGS. 1 to 5 . 
         [0062]      FIGS. 12 to 16  are plan views schematically illustrating each process of manufacturing a piezoelectric component, according to this embodiment. 
         [0063]      FIGS. 12 to 16  are plan views, viewed from the upper face side. The part of the piezoelectric component under the piezoelectric mother substrate  91  is not shown, but is the same as that above the piezoelectric mother substrate  91 . 
         [0064]    In the method of manufacturing a piezoelectric component according to this embodiment, first, a piezoelectric mother substrate  91  having a plurality of element regions  92  which are each separately formed into a piezoelectric oscillating element  10  is prepared ( FIG. 12 ). 
         [0065]    Each element region  92  of the piezoelectric mother substrate  91  is previously provided with electrodes  20   a  and  20   b  on the respective major surfaces thereof. The boundaries between each element region  92  of the piezoelectric mother substrate  91  are provided with dicing lines  93  which are removed by dicing later. 
         [0066]    Then, an electrically conductive bump  97 , which is divided into 4 parts by dicing later, is formed at each position which becomes a portion between the ends of adjacent extractor electrodes  22   a  of the electrodes  20   a  and at each position which becomes a portion between the ends of adjacent extractor electrodes  22   b  of the electrodes  20   b  ( FIG. 13 ). 
         [0067]    This provides a favorable connection of the extractor electrode  22   a  to terminal electrodes  61   a  and  61   b  and a favorable connection of the extractor electrode  22   b  to terminal electrodes  62   a  and  62   b.    
         [0068]    Then, lattice bodies  94  composed of a light-transmissive resin material are formed on both major surfaces of the piezoelectric mother substrate  91  so as to cover both major surfaces, other than regions of vibrating electrodes  21   a  and  21   b,  of the piezoelectric mother substrate  91  ( FIG. 14 ). 
         [0069]    The lattice bodies  94  are to be divided together with the element regions  92  along the dicing lines  93  into frames  30  on the respective piezoelectric oscillating elements  10 . 
         [0070]    Then, sealing mother substrates  95  composed of a light-transmissive resin material are attached so as to cover the lattice bodies  94  ( FIG. 15 ). 
         [0071]    Thus, each element region  92  of the piezoelectric mother substrate  91 , each portion of the lattice body  94  which becomes the frame  30 , and the sealing mother substrate  95   a  form a sealed space S at each element region  92 . 
         [0072]    Since the lattice bodies  94  and the sealing mother substrates  95  are both composed of light-transmissive resin materials, the formed state of the sealed spaces S can be observed by appearance inspection such as visual observation or image recognition. In addition, it can be observed by appearance inspection such as visual observation or image recognition whether or not continuous bubbles or the like, which reduce the hermeticity of sealed spaces S, are present in the insides of the lattice bodies  94 , in the interfaces between the lattice bodies  94  and the piezoelectric mother substrate  91 , or interfaces between the lattice bodies  94  and the sealing mother substrates  95 . 
         [0073]    Furthermore, it can be checked by appearance inspection such as visual observation or image recognition whether or not there are narrowed portions in sealing widths (indicated by “d” in  FIG. 2 ) formed by the frames  30   a  and  30   b.    
         [0074]    When a defective piece is found by these appearance inspections, the defective piece can be removed after the dividing process. Therefore, a piezoelectric component improved in reliability can be manufactured. 
         [0075]    Then, after the process of forming a plurality of sealed spaces S shown in  FIG. 15 , coating layers  50   a  and  50   b  composed of a light-shielding (opaque) resin are formed on the respective external surfaces of the sealing mother substrates  95  ( FIG. 16 ). 
         [0076]    On the coating layers  50   a  and  50   b  composed of a light-shielding resin material, marks M are formed. 
         [0077]    Though one additional step, for example, the step of forming the coating layers  50   a  and  50   b,  is necessary for providing marks M on the coating layers  50   a  and  50   b,  the visibility of the marks M can be enhanced compared to the case in which the marks M are directly provided on the sealing substrates  40   a  and  40   b  composed of a light-transmissive resin material. Consequently, a false perception of marks M can be reduced, and a manufacturing method improved in productivity can be provided. In marks M with a depth of 3 μm or more, the visibility is further improved. 
         [0078]    Furthermore, the coating layers  50   a  and  50   b  can be marked with marks M by using laser light, which is difficult to be used for light-transmissive resins. Thereby, marks M improved in wear resistance can be provided. The laser used in printing may be a YAG laser (wavelength: 1064 nm) or a CO2 laser (wavelength: 10.6 μm), for example. It is preferable that the laser have a shorter wavelength in view of improved color development of the resin used as the coating layer. In general, a laser having a wavelength of approximately 1064 nm is preferred. 
         [0079]    The process using laser light is improved in printing speed compared to that in printing such as ink-jet printing. Therefore, a manufacturing method improved in productivity can be provided. 
         [0080]    Then, external connection electrodes  71 ,  72 , and  73  are formed on the bottom face of the lower coating layer  50   b,  and then piezoelectric components are cut into each one by dicing ( FIG. 16 ). The dicing can be precisely performed by putting marks for dicing with the same material as that of the external connection electrodes  71 ,  72 , or  73  when they are formed. 
         [0081]    In the method of manufacturing a piezoelectric component according to this embodiment, as shown in  FIG. 12 , reference patterns  96  may be formed together with the electrodes  20   a  and  20   b  on both major surfaces of the piezoelectric mother substrate  91 . The reference patterns  96  are formed along and near the dicing lines  93  for confirming the dicing lines  93  so as to have the same width as that of a dicing blade. In such a case, the coating layers  50   a  and  50   b  are not formed over the entire external surfaces of the upper and lower sealing substrates  40   a  and  40   b,  but are formed only over the regions where marks are provided so that the reference patterns  96  are not covered with the coating layers  50   a  and  50   b.  The reference patterns  96  on the major surfaces of the piezoelectric substrate  11  can be viewed by thus forming the coating layers  50   a  and  50   b  at the defined areas. Therefore, dicing can be performed using the reference patterns  96  as indication for dicing. 
         [0082]    Lastly, input/output terminal electrodes  61  and  62  and ground terminal electrodes  63  are formed on the respective side faces to complete a piezoelectric component  1 . 
         [0083]    Shapes and manufacturing materials of the piezoelectric component according to the present invention will now be described. 
         [0084]    The piezoelectric substrate  11  and the piezoelectric mother substrate  91  are composed of a piezoelectric ceramic material including a base material such as lead zirconate titanate (PZT), lead titanate (PT), sodium potassium niobate (Na1-xKxNbO3), or a bismuth layer-structured compound (for example: MBi4Ti4O15, M: divalent alkaline earth metal element); or a piezoelectric single crystal such as quartz crystal or lithium tantalate. 
         [0085]    The piezoelectric substrate  11  is preferably a rectangle having a length of 0.6 to 5 mm, a width of 0.2 to 5 mm, and a thickness of 40 μm to 1 mm, from the viewpoint of miniaturization and properties for mounting on a circuit substrate. 
         [0086]    Furthermore, the piezoelectric substrate  11  is not required to have a uniform thickness over the entire surface. For example, a vibration area A may have a thickness smaller or larger than that of the surrounding area, in order to enhance the energy confinement of thickness vibration and improve the resonance characteristics. 
         [0087]    In addition, in order to further improve the resonance characteristics, for example, the piezoelectric substrate  11  may be provided with an internal electrode composed of Ag—Pd as a vibration electrode. 
         [0088]    Furthermore, a piezoelectric substrate  11  having a relative dielectric constant of 1000 or less is preferred, in view of better resonance in a high frequency region. 
         [0089]    In a piezoelectric substrate  11  composed of a ceramic material, a raw material powder is formed into a sheet by, for example, adding a binder to the raw material powder and pressing the mixture into a sheet or mixing the raw material powder with water and a dispersing agent using a ball mill, drying the mixture, adding a binder, a solvent, a plasticizer, and the like to the mixture, and forming the resulting mixture into a sheet by a doctor blade method; the sheet is fired at a peak temperature of 1100 to 1400° C. for 0.5 to 8 hours to form a substrate; and the substrate is polarized in the thickness direction by applying, for example, a voltage of 3 to 6 kV/mm at 80 to 200° C. to obtain a piezoelectric substrate  11  having the desired piezoelectric characteristics. 
         [0090]    In a piezoelectric substrate  11  composed of a piezoelectric single crystal material, a piezoelectric substrate  11  having desired piezoelectric characteristics is obtained by cutting an ingot (base material) of the piezoelectric single crystal material so as to have a predetermined crystal direction. 
         [0091]    The electrodes  20   a  and  20   b  are preferably composed of a metal film such as gold, silver, copper, or aluminum, from the viewpoint of electrical conductivity. The thickness is preferably in the range of 0.1 to 3 μm. In a metal film having a thickness less than 0.1 μm, for example, the conductivity tends to be readily decreased by oxidation when the metal film is left in the air at a high temperature. In a metal film having a thickness larger than 3 μm, the film tends to be readily peeled. 
         [0092]    The adhesion of the metal films described above to the substrate may be performed by applying the film to the substrate by a vacuum deposition method, a PVD method, a sputtering method, or a thick film printing method and then baking them. 
         [0093]    In addition, in order to enhance the adhesion with the piezoelectric substrate  11 , for example, base electrode layers composed of a material, such as Cr, having a high adhesion to a ceramic substrate are previously formed and desired metal films may be formed thereon. 
         [0094]    After adhesion of the metal films to both of the entire major surfaces of the piezoelectric substrate  11 , photoresist films having a thickness of 1 to 10 μm are formed on the metal films by spin coating, for example. Then, various types of electrodes can be formed by patterning by photoetching. 
         [0095]    The vibrating electrodes  21  are arranged at approximately the center of both major surfaces of the piezoelectric substrate  11  and are of a rectangular shape with longitudinal and transverse lengths of several tens of micrometers to several millimeters or of a circular shape. The details in shape and size are determined based on resonator characteristics and other desired electric characteristics. 
         [0096]    The frames  30  (and the lattice bodies  94 ) are composed of a light-transmissive resin material, for example, a resin material containing a base material such as a phenol resin, a polyimide resin, or an epoxy resin. 
         [0097]    In particular, a base material of the epoxy resin is not only good in insulating properties, but also has high adhesion to ceramics and is good in moisture resistance and heat resistance, and thereby is preferred. 
         [0098]    An epoxy resin of a curing type, not hydrolyzed, is preferred. In addition, an epoxy resin to which particles of rutile titanium oxide are added for reducing the moisture permeability or to which 2,4-diamino-6-vinyl-S-triamine and isocyanuric acid are added for enhancing insulation properties can be used. 
         [0099]    These resin materials can be used, for example, a thermal-curable or photo-curable resin is applied on the piezoelectric substrate  11  by screen printing or transcription so as to have a thickness of 1 to 80 μm and is then cured by heating or ultraviolet irradiation. 
         [0100]    Frames  30  (and the lattice bodies  94 ) having a thickness of 20 to 60 μm are particularly preferred from the viewpoint of achieving a piezoelectric component reduced in thickness while a favorable height of the sealed spaces is maintained. 
         [0101]    The lattice bodies  94  formed on the piezoelectric substrate  11  may have upper faces having convex shapes. With such shapes, bubbles, which reduce hermeticity of the sealed spaces, are effectively prevented from remaining in the connecting faces of the lattice bodies  94  and the sealing substrates  40  during connecting them. 
         [0102]    The sealing substrates  40   a  and  40   b  are composed of a light-transmissive resin material and are attached on the top and bottom faces of the piezoelectric oscillating element  10  via the frames  30   a  and  30   b  and form sealed spaces with the frames  30   a  and  30   b.  The longitudinal and transverse lengths of the sealing substrates  40   a  and  40   b  are usually approximately the same as those of the piezoelectric substrate  11 . The thickness of the sealing substrate  40   a,  which is placed at the upper side, may be 10 μm or more, but the thickness of the sealing substrate  40   b,  which is placed at the lower side, is preferably 20 μm or more from the viewpoint of preferably achieving a function of absorbing stress from a mounting substrate and mechanical and thermal shocks, and preferably 100 μm or less from the viewpoint of reducing the thickness of the piezoelectric component. 
         [0103]    Furthermore, the sealing substrates  40   a  and  40   b  are required to have suitable elasticity. When measured by DMA (Dynamic Mechanical Analysis), an elastic modulus in the range of 2 to 60 GPa is preferred, and that in the range of 2 to 20 GPa is particularly preferred from the viewpoint of the function of absorbing shocks. 
         [0104]    Sealing substrates  40   a  and  40   b  (and sealing mother substrates  95 ) composed of a resin sheet material which is prepared by impregnating fiberglass cloth or aramid fiber cloth with a polyimide resin or an epoxy resin can suppress thermal deformation of the sealing substrate  40   a  to surely form sealed spaces and be improved in mechanical strength. 
         [0105]    In particular, a polyimide resin or epoxy resin sheet containing 30 to 80% fiberglass having an adhesion function (prepreg) is preferred and is favorably cured by being maintained at 150 to 200° C. at a pressure of 0.2 to 5 MPa for 5 to 90 minutes under in a vacuum of 100 Pa or less or in the atmosphere. 
         [0106]    Since an adhesive for attaching between the sealing substrates  40  and the lattice bodies  94  is not necessary, materials and the number of steps can be reduced, and an efficient manufacturing method is provided. 
         [0107]    Alternatively, the sealing substrates  40  may be composed of a plurality of resin sheets having different characteristics. Such sealing substrates  40  may be improved totally in various characteristics such as mechanical strength, shock resistance, and moisture resistance. 
         [0108]    The light transmissivity of the sealing substrates  40   a  and  40   b  composed of a resin material can be mainly adjusted by controlling the thickness of the sealing substrates  40   a  and  40   b,  types of the resin material, and types and amounts of additives added to the resin material. For example, in sealing substrates  40   a  and  40   b  including an epoxy resin as the resin material, a light transmissivity of 50% can be obtained by adding 15 wt % of a coloring additive such as carbon black based on 100 wt % of the epoxy resin and forming the sealing substrates so as to have a thickness of 150 μm. 
         [0109]    The coating layers  50   a  and  50   b  are composed of a light-shielding resin material and are formed on the external surfaces of the sealing substrates  40   a  and  40   b.  The coating layers  50   a  and  50   b  have a thickness of 5 to 50 μm and are preferably composed of a colored resin prepared by, for example, mixing a pigment such as carbon black and a dispersing agent in a powder form with a usual resin such as an epoxy resin or a polyimide resin. In addition, the coating layers  50   a  and  50   b  may be composed of a resin material prepared by impregnating fiberglass cloth or aramid fiber cloth with a light-shielding resin. 
         [0110]    Furthermore, at least one of the coating layers  50   a  and  50   b  is provided with various marks representing information about the piezoelectric component  1 , and external connection electrodes  71 ,  72 , and  73  are formed on the bottom face of the coating layer  50   b.  The marking may be performed by printing such as ink-jet printing or by stamping using laser light, as described above. 
         [0111]    The terminal electrodes  61 ,  62 , and  63  and the external connection electrodes  71 ,  72 , and  73  may be highly conductive metal films, such as gold, silver, copper, or aluminum, but are preferably formed of an electrically conductive epoxy resin, from the viewpoint of adhesive strength to a resin, preferably with 75 to 95 mass % of an electrically conductive filler such as silver, copper, or nickel, from the viewpoint of electrical conductivity. 
         [0112]    An electrically conductive resin having an appropriate elasticity can improve a function of absorbing stress from a mounting substrate and shocks. Thus, a piezoelectric component having high reliability can be obtained. 
         [0113]    A metal filler having a smaller particle diameter is preferred, from the viewpoint of smoothing the electrically conductive resin surface and improving mountability. However, in view of printability, a metal filler having an average particle diameter of 0.5 to 5 μm is preferred. 
         [0114]    When the electrically conductive film is too thin, the conductivity may be reduced. When the film is too thick, the electrically conductive film tends to be readily peeled off by stress during mounting. Therefore, a thickness in the range of 10 to 60 μm is preferred. 
         [0115]    The adhesion of such an electrically conductive resin may be performed by applying the resin by a known method such as screen printing or roller transcription and then curing the resin by heating or ultraviolet irradiation. 
         [0116]    Furthermore, at least one plating film of such as Cu, Ni, Sn, or Au may be formed on the surface of the electrically conductive resin if desired. Thereby, the solderability can be improved. 
         [0117]    The dielectric substrate  81  has a function of forming load capacitors with the hot-side capacitor electrodes  82   a  and  82   b  and the ground-side capacitor electrode  83 , and also has a function of protecting the piezoelectric substrate  11  from external forces. The dielectric substrate  81  is composed of a ferroelectric ceramic material such as lead zirconate titanate (PZT), lead titanate (PT), or barium titanate (BT) and is a rectangular single plate with a length of 0.6 to 5 mm, a width of 0.2 to 5 mm, and a thickness of several tens of micrometers to one millimeter, from the viewpoint of mountability on a circuit substrate. 
         [0118]    This dielectric substrate  81  is prepared by forming a raw material powder into a sheet, for example, by adding a binder to the raw material powder and pressing the mixture into a sheet or by mixing the raw material powder with water and a dispersing agent using a ball mill, drying the mixture, adding a binder, a solvent, a plasticizer, and the like to the dried mixture, and forming the resulting mixture into a sheet by a doctor blade method; and firing the sheet at a peak temperature of 1100 to 1400° C. for several tens of minutes to several hours. 
         [0119]    In the dielectric substrate  81  composed of a ferroelectric ceramic material such as lead zirconate titanate (PZT), lead titanate (PT), or barium titanate (BT), the relative permittivity of the dielectric substrate  81  can be increased. Therefore, a capacitor element  80  having a sufficiently large electrostatic capacity can be obtained. A dielectric substrate  81  having a relative permittivity of 200 to 5000 is preferred. 
         [0120]    The hot-side capacitor electrodes  82   a  and  82   b  and the ground-side capacitor electrode  83  are formed by application of an electrically conductive resin or an electrically conductive paste by a conventional method such as screen printing and then curing the resin by ultraviolet irradiation or heating, or firing the paste. 
         [0121]    As the electrically conductive paste, a high-temperature firing type conductive paste containing 75 to 95% mass of silver powder to which a glass powder, a resin or oil, and a solvent are added and being fired at 400 to 800° C. is preferred. 
         [0122]    As the electrically conductive resin, a conductive resin containing 75 to 95% mass of an electrically conductive filler such as silver is preferred. In the electrically conductive paste or the electrically conductive resin, an electrode thickness of 8 to 15 μm is preferred. 
         [0123]    The electrodes may be formed by deposition of a highly electrically conductive metal film of gold, silver, copper, aluminum, or the like by, for example, a vacuum deposition method, a PVD method, or a sputtering method; then formation of a photoresist film having a thickness of 1 to 10 μm on the metal film by, for example, spin coating; and patterning by photoetching. 
         [0124]    In such a case, in order to enhance the adhesion of the electrodes to the piezoelectric substrate  11 , an under-electrode layer composed of, for example, Cr, which has high adhesion to a ceramic substrate, may be previously formed, and then a desired metal film may be formed thereon. 
         [0125]    The electrically conductive bump  97  is formed by application of an electrically conductive resin or an electrically conductive paste by a conventional method such as screen printing and then curing the resin by ultraviolet irradiation or heating or firing the paste. 
         [0126]    As the electrically conductive paste, a high-temperature firing type conductive paste containing 75 to 95% mass of silver powder to which a glass powder, a resin or oil, and a solvent are added and being fired at 400 to 800° C. is preferred. 
         [0127]    As the electrically conductive resin, a conductive resin containing 75 to 95% mass of an electrically conductive filler such as silver is preferred. 
         [0128]    The reference patterns  96  may be formed simultaneously when the electrodes  20   a  and  20   b  are formed with the same material and method as those in the electrodes  20   a  and  20   b.  Alternatively, the reference patterns may be formed with a material, such as a non-electrically conductive pigment, different from that of the electrodes by screen printing, for example. 
         [0129]    The present invention is not limited to the above-mentioned embodiments and can be variously modified or improved within the scope of the present invention. 
         [0130]    For example, in the above-mentioned embodiments, the coating layers  50   a  and  50   b  are disposed at the respective external sides of the upper and lower sealing substrates  40   a  and  40   b.  However, the coating layer  50   a  or  50   b  may be disposed on only the sealing substrate  40   a  or on only the other sealing substrate  40   b.    
         [0131]    Furthermore, the sealing substrates  40   a  and  40   b  may be directly marked without forming the coating layers  50   a  and  50   b.  In such a case, in view of visibility of marks, it is preferable that the light transmissivity of the sealing substrates  40   a  and  40   b  be decreased to a certain degree. For example, a piezoelectric component which is improved in visibility of marks and allows visual inspection of conditions of sealed spaces can be obtained by adjusting the light transmissivity of the sealing substrates  40   a  and  40   b  to within the range of 25 to 75%, when the marking is conducted using a YAG laser. In the case that the sealing substrates  40   a  and  40   b  are directly provided with marks, the coating layers  50   a  and  50   b  are not necessary. Consequently, a piezoelectric component having a reduced thickness can be obtained. In addition, since the process of forming the coating layers  50   a  and  50   b  is not necessary, the productivity can be advantageously improved.