Abstract:
A method of manufacturing a resonance element includes the steps of preparing a multilayered body having a plurality of piezoelectric layers and a plurality of inner electrodes laminated to each other, forming an insulating film on one surface of the multilayered body at exposed portions of the inner electrodes, the insulating film having a plurality of openings constituting substantially parallel rows which are substantially parallel to the laminating direction of the multilayered body, forming an outer electrode on substantially the entire surface on which the insulating film is formed, forming a plurality of grooves on the surface on which the outer electrode is formed and cutting the multilayered body substantially parallel to the grooves, wherein a first group of the openings in a first of the rows are disposed on every alternate exposed portion of the internal electrodes, and a second group of remaining openings in a second row adjacent to the first row are disposed on each of the remaining alternate exposed portions of the internal electrodes, the first and second row are separated from each other by a predetermined distance and the groove is formed between the first and second rows.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of manufacturing a piezoelectric resonator. More particularly, the present invention relates to a method of manufacturing a piezoelectric resonator which is provided in electronic components, such as an oscillator, a discriminator, and a filter, and which uses mechanical resonance of a piezoelectric body. 
     2. Description of the Related Art 
     FIG. 26 is a perspective view showing an example of a conventional piezoelectric resonator. A piezoelectric resonator  1  shown in FIG. 26 includes a piezoelectric substrate  2 , for example, having a rectangular plate shape. The piezoelectric substrate  2  is polarized along the thickness direction thereof. Electrodes  3  are provided on both major surfaces of the piezoelectric substrate  2 . As a result of inputting a signal between these electrodes  3 , an electric field is applied along the thickness direction of the piezoelectric substrate  2 , causing the piezoelectric substrate  2  to vibrate along the length direction thereof. 
     The piezoelectric resonator shown in FIG. 26 is an unstiffened type, in which the vibration direction is different from the electric-field direction and the polarization direction. An electro-mechanical coupling coefficient of a piezoelectric resonator of such an unstiffened resonator is lower than that of a stiffened piezoelectric resonator, in which the electric-field direction, the polarization direction, and the vibration direction coincide with each other. Therefore, in the unstiffened type piezoelectric resonator, the difference ΔF between the resonance frequency and the anti-resonance frequency is relatively small. This causes a very small bandwidth when such an unstiffened piezoelectric resonator is used for a filter. Therefore, the degree of characteristic design freedom is small in such an unstiffened piezoelectric resonator and electronic components incorporating such a resonator. 
     Furthermore, in the piezoelectric resonator shown in FIG. 26, a primary resonance of a length mode is used. However, due to the structure of the resonator shown in FIG. 26, an odd-number multiple high-order mode, such as a third order mode or a fifth order mode, and a large spurious vibration of a width mode, are generated. 
     Japanese Patent Application No. 8-110475, filed by the applicant of the present invention, describes a piezoelectric resonator having a multilayered base structure having a longitudinal direction which is provided as a result of a plurality of piezoelectric layers and a plurality of electrodes being alternately stacked and laminated. The plurality of piezoelectric layers are polarized along the length direction of the base, and a fundamental vibration of a longitudinal vibration is excited. The piezoelectric resonator of such a multilayered structure is a stiffened type resonator, in which the polarization direction, the electric-field direction, and the vibration direction are the same. As a result, such a stiffened resonator has spurious emissions that are smaller than that of an unstifffened type resonator, and the difference ΔF between the resonance frequency and the anti-resonance frequency is large in this stiffened type resonator. 
     Next, an example of a piezoelectric resonator having such a multilayered structure will be described in detail. FIG. 1 is a perspective view showing an example of a conventional piezoelectric resonator having a multilayered structure, to provide a background against which-the present invention will be compared later. FIG. 2 is a schematic view of the piezoelectric resonator. FIG. 3 is a plan view of the essential portion of the piezoelectric resonator. 
     A piezoelectric resonator  10  in FIG. 1 having such a multilayered structure includes a base  12 , for example, having a rectangular body. The base  12  includes a plurality of piezoelectric layers  12   a , which are formed from, for example, a piezoelectric ceramic, and are multilayered. In the plurality of piezoelectric layers  12   a  in the intermediate portion along the length direction of the base  12 , a plurality of internal electrodes  14  are disposed on each of the two main surfaces so as to be perpendicular relative to the length direction of the base  12 . Therefore, a plurality of internal electrodes  14  are disposed and spaced apart in a direction that is perpendicular to the length direction of the base  12  and along the length direction of the base  12 . Also, the plurality of piezoelectric layers  12   a  in the intermediate portion along the length direction of the base  12 , as indicated by the arrows in FIG. 2, are polarized along the length direction of the base  12  so that adjacent piezoelectric layers are oppositely polarized relative to each other on both sides of the respective internal electrodes  14 . However, the piezoelectric layers  12   a  of both end portions along the length direction of the base  12  are not polarized. In this base  12 , the internal electrodes  14  are exposed at four side surfaces which are parallel to the length direction of the base  12 . 
     A groove  15  which extends along the length direction of the base  12  is formed on one side surface of the base  12 . The groove  15  is formed in the center in the width direction of the base  12 , dividing one side surface of the base  12  into two portions. Furthermore, as shown in FIG. 2, a first insulation film  16  and a second insulation film  18  are disposed on the side surfaces divided by the groove  15 . On one side divided by the groove  15  on the side surface of the base  12 , every alternate exposed portion of the internal electrodes  14  is covered by the first insulation film  16 . Also, on the other side divided by the groove  15  on the side surface of the base  12 , the exposed portions of the internal electrodes  14  that are not covered by the first insulation film  16  on one side of the groove  15  are covered by the second insulation film  18 . 
     Furthermore, at the portions where the first and second insulation films  16  and  18  of the base  12  are disposed, that is, on both sides of the groove  15 , two external electrodes  20  and  22  are disposed. Therefore, the internal electrodes  14  that are not covered by the first insulation film  16  are connected to the external electrode  20 , and the internal electrodes  14  that are not covered by the second insulation film  18  are connected to the external electrode  22 . That is, adjacent internal electrodes  14  are connected to the external electrode  20  and the external electrode  22 , respectively. 
     In this piezoelectric resonator  10 , the external electrodes  20  and  22  are used as input and output electrodes. In the intermediate portion along the length direction of the base  12 , since the section between adjacent internal electrodes  14  is polarized and an electric field is applied between the adjacent internal electrodes  14 , the section is piezoelectrically active. Since mutually opposite voltages are applied to the portions of the base  12  which are mutually oppositely polarized, the base  12  expands or contracts in the same direction as a whole. Therefore, in the entire piezoelectric resonator  10 , a fundamental vibration in a longitudinal vibration mode, in which the center portion along the length direction of the base  12  is a node, is excited. Both end portions along the length direction of the base  12  are not polarized, and an electric field is not applied thereto because no electrode is disposed at the end portions. Therefore, both end portions are piezoelectrically inactive. 
     In this piezoelectric resonator  10 , the polarization direction of the base  12 , the electric-field direction applied by the input signal, and the vibration direction of the base  12  are the same. That is, this piezoelectric resonator  10  is a stiffened piezoelectric resonator. This piezoelectric resonator  10  has an electro-mechanical coupling coefficient greater than that of an unstiffened type, such that the polarization direction, the electric-field direction, and the vibration direction are different from each other. Therefore, in this piezoelectric resonator  10 , it is possible to increase the selectable width of the difference ΔF between the resonance frequency and the anti-resonance frequency in comparison with an unstiffened piezoelectric resonator. Therefore, in this piezoelectric resonator  10 , it is possible to obtain a characteristic with a larger bandwidth than that of an unstiffened resonator. Furthermore, this piezoelectric resonator  10  has spurious emissions which are smaller than that of an unstiffened resonator. In addition, in this. piezoelectric resonator  10 , since the external electrodes  20  and  22  are disposed on a single common side surface thereof, the resonator  10  can be surface-mounted onto, for example, an insulator substrate. 
     A method of manufacturing this piezoelectric resonator  10  will be described below with reference to FIGS. 4 to  13 . In these figures, for convenience of description, the number of layers of green sheets which form the piezoelectric layers  12   a  does not coincide with the number of layers of the piezoelectric layers  12   a  which form the piezoelectric resonator  10  shown in FIGS. 2 and 3. However, the following manufacturing process is the same regardless of the number of piezoelectric layers. 
     When manufacturing this piezoelectric resonator  10 , as shown in FIG. 4, a green sheet  30  is prepared first. Conductive paste containing, for example, silver, palladium, an organic binder, and the like, is coated onto one surface of the green sheet  30 , forming a conductive paste layer  32 . The conductive paste layer  32  is formed on the entire surface excluding one end side of the green sheet  30 . A plurality of the green sheets  30  are stacked in layers. At this time, the green sheets  30  are multilayered so that alternate end portions which are not formed with the conductive paste layer  32  are disposed in mutually opposite directions. Furthermore, since a conductive paste is coated onto the opposing side surfaces of the multilayered body and then sintered, a multilayered base  34  such as that shown in FIG. 5 is formed. 
     Inside the multilayered base  34 , as a result of the conductive paste layer  32  being sintered, a plurality of internal electrodes  36  are formed. These internal electrodes  36  are alternately exposed at the opposing portions of the multilayered base  34 . Then, in the opposing portions of the multilayered base  34 , electrodes  38  and  40  for polarization are formed, to which each alternate internal electrode  36  is connected. By applying a direct-current voltage to these polarization electrodes  38  and  40 , a polarization process is performed on the multilayered base  34 . At this time, inside the multilayered base  341  a direct-current high electric-field is applied between adjacent internal electrodes  36 , and the directions of the applied electric field are opposite to each other. Therefore, the multilayered base  34  is polarized in mutually opposite directions on both sides of the internal electrodes  36 , as indicated by the arrows in FIG.  5 . 
     Next, as indicated by the dotted line in FIG. 6, the multilayered base  34  is cut by a dicer or the like in such a manner as to intersect at right angles to the plurality of internal electrodes  36  and the polarization electrodes  38  and  40 . As a result, a multilayered body  42  such as that shown in FIG. 7 is formed. 
     Then, as shown in FIG. 8, an insulation film  44  is arranged in such a manner as to form a checkered pattern on one main surface of the multilayered body  42 . In this case, in one row in the vertical direction with respect to the internal electrodes  36  of a checkered pattern, the insulation film  44  is disposed on alternate internal electrodes  36  in the vertical direction with respect to the internal electrodes  36  of the multilayered body  42 . Also, in a row which is vertical with respect to the adjacent internal electrodes  36  of the multilayered body  42 , the insulation film  44  is formed on the internal electrodes  36  which are not covered with the insulation film  44  in the adjacent row. 
     Thereafter, in this multilayered body  42 , on the entire surface where the insulation film  44  is formed, as shown in FIG. 9, an external electrode  48  is formed by sputtering or the like. 
     Next, in the multilayered body  42 , the groove  15  is formed so as to intersect at right angles to the surface of the internal electrodes  36  by a dicing machine in the portion indicated by the one-dot-chain line in FIG. 10, specifically, in the portion between the one-dot-chain lines of FIG. 11, that is, on the main surface of the multilayered body  42  in the boundary portion of adjacent rows of the insulation film  44  arranged in a checkered pattern, and further, by cutting the multilayered body  42  as shown in FIG. 12, the piezoelectric resonator  10  shown in FIGS. 1 and 2 is formed in the portion indicated by the dotted line in FIG. 10, specifically, in the portion between the one-dot-chain lines of FIG. 11, that is, in the intermediate portion of these grooves  15 . 
     However, in the above-described method, when the position at which the groove  15  is formed in the multilayered body  42  is deviated by ½ or more of the edge thickness (corresponding to the width of the groove  15 ) of a dicing machine, for example, as shown in FIG. 13, the groove  15  is deviated from the boundary of the adjacent rows of the insulation film  44 . In this case, in the piezoelectric resonator  10  to be formed, as shown in FIG. 14, the internal electrodes  36  ( 14 ) to be insulated are not insulated completely by the insulation film  44  ( 16 ), and the section between external electrodes  48  ( 20 ) and  48  ( 22 ) is short-circuited. In this manner, in the above-described method, the groove  15  must be formed so as to include the edge of the insulation film  44 , and the position at which the groove  15  is formed requires high accuracy, making it difficult to manufacture the piezoelectric resonator  10  with a high yield of non-defective products. 
     SUMMARY OF THE INVENTION 
     To overcome the problems with conventional devices described above, the preferred embodiments of the present invention provide a method of manufacturing a piezoelectric resonator, such that a surface-mountable piezoelectric resonator having a multilayered structure can easily be manufactured accurately and with a high yield of non-defective products. 
     The preferred embodiments of the present invention provide a method of manufacturing a resonance element, including the steps of preparing a multilayered body having a plurality of piezoelectric layers and a plurality of inner electrodes laminated to each other, forming an insulating film on one surface of the multilayered body at exposed portions of the inner electrodes, the insulating film having a plurality of openings constituting substantially parallel rows which are substantially parallel to the laminating direction of the multilayered body, forming an outer electrode on substantially the entire surface on which the insulating film is located, forming a plurality of grooves on the surface on which the outer electrode is located and cutting the multilayered body substantially parallel to the grooves, wherein a first group of the openings in a first of the rows are disposed on each alternate exposed portion of the internal electrodes, and a second group of the openings in a second row adjacent to the first row are disposed on each of the remaining alternate exposed portions of the internal electrodes, the first and second rows being separated from each other by a predetermined distance, and the groove is located between the first and second rows. 
     In the above described method, a relationship 0&lt;x&lt;(W−a)/2 is preferably satisfied where W is the width of the piezoelectric resonator, a is the width of the groove, and x is the dimension of the predetermined distance between the first row and the adjacent second row. 
     According to preferred embodiments of the present invention, a surface-mountable piezoelectric resonator having a multilayered structure is manufactured. 
     Also, in a method of manufacturing a piezoelectric resonator in accordance with preferred embodiments of the present invention, an insulation film is formed in such a way that the first and second rows are separated by a predetermined distance. Therefore, even if the position at which a groove is formed in the multilayered body is slightly deviated from a predetermined position, no short-circuit occurs between electrodes, and it is easy to manufacture a piezoelectric resonator with a high yield of non-defective products. 
     Other features and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention which refers to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an example of a piezoelectric resonator relating to a background of the present invention. 
     FIG. 2 is a schematic view of the piezoelectric resonator shown in FIG.  1 . 
     FIG. 3 is a plan view of the essential portion of the piezoelectric resonator shown in FIG.  1 . 
     FIG. 4 is a perspective view showing a state in which ceramic green sheets and the like are stacked and laminated to produce a piezoelectric resonator. 
     FIG. 5 is a schematic view showing a multilayered base made from ceramic green sheets shown in FIG.  4 . 
     FIG. 6 is a schematic view showing a portion where the multilayered base shown in FIG. 4 is cut. 
     FIG. 7 is a schematic view showing a multilayered base such that the multilayered base shown in FIG. 6 is cut. 
     FIG. 8 is a schematic view showing a state in which an insulation film is disposed in the multilayered base shown in FIG.  7 . 
     FIG. 9 is a schematic view showing a state in which an external electrode is disposed in the multilayered base shown in FIG.  8 . 
     FIG. 10 is a schematic view showing a step for manufacturing a piezoelectric resonator by forming a groove in the multilayered base shown in FIG.  9  and cutting the multilayered base. 
     FIG. 11 is a schematic view of the essential portion of the step shown in FIG.  10 . 
     FIG. 12 is a schematic view showing the piezoelectric resonator manufactured in the step shown in FIG.  11 . 
     FIG. 13 is a schematic view of the essential portion showing a step in a case in which the position at which a groove is formed in the multilayered base and the position at which the multilayered base is cut are deviated in the step shown in FIG.  11 . 
     FIG. 14 is a schematic view showing the piezoelectric resonator manufactured in the step shown in FIG.  13 . 
     FIG. 15 is a schematic view of the essential portion showing a step for manufacturing a piezoelectric resonator by forming a groove in the multilayered base and cutting the multilayered base in the method of manufacturing a piezoelectric resonator according to preferred embodiments of the present invention. 
     FIG. 16 is a schematic view showing the piezoelectric resonator manufactured by the process shown in FIG.  15 . 
     FIG. 17 is a schematic view of the essential portion showing a step in a case in which the position of a groove and cutting position are deviated in the step shown in FIG.  15 . 
     FIG. 18 is a schematic view showing the piezoelectric resonator manufactured by the process shown in FIG.  17 . 
     FIG. 19 is a schematic view of the essential portion showing a step in a case in which the position of a groove and cutting position are deviated in the step shown in FIG.  15 . 
     FIG. 20 is a schematic view showing the piezoelectric resonator manufactured by the process shown in FIG.  19 . 
     FIG. 21 is an exploded perspective view showing an example of an electronic component including the piezoelectric resonator shown in FIG.  1 . 
     FIG. 22 is a side view showing the mounting construction of the piezoelectric resonator in the electronic component shown in FIG.  21 . 
     FIG. 23 is a plan view of the essential portion showing an example of a ladder filter including the piezoelectric resonator shown in FIG.  1 . 
     FIG. 24 is an exploded perspective view of the essential portion of the ladder filter shown in FIG.  23 . 
     FIG. 25 is a circuit diagram of the ladder filter shown in FIG.  23 . 
     FIG. 26 is a perspective view showing an example of a conventional piezoelectric resonator relating to a background of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A preferred embodiment of a method of manufacturing a piezoelectric resonator similar to the piezoelectric resonator  10  shown in FIGS. 1 and 12 will now be described. 
     Initially, a multilayered body  42  shown in FIG. 7 is made by the same steps as used in a method of manufacturing the piezoelectric resonator  10  shown in FIGS. 1 and 12. 
     Then, as shown in FIG. l 5 E an insulation film  44  is formed on one surface of this multilayered body  42  in such a way that overlapping portions  46  which are continuous in a vertical direction with respect to the internal electrodes  36  are provided instead of the checkered pattern shown in FIG.  8 . That is, a first row of openings at  48 ( 20 ) and a second row of openings at  48 ( 22 ) adjacent to the first row of openings at  48 ( 20 ), each of which rows is substantially parallel to the laminating direction of the multilayered body, are separated from each other by a predetermined distance. 
     Thereafter, in this multilayered body  42 , as shown in FIG. 15, external electrodes  48  are formed by sputtering or similar processes on the entire surface of the surface where the insulation film  44 , including the overlapping portion  46 , is formed. 
     Next, in the multilayered body  42 , a groove  15  is formed by a dicing machine so as to intersect at right angles to the surface of the internal electrodes  36  in the portion indicated by the one-dot-chain line in FIG. 15, that is, in an approximately central portion of the overlapping portions  46  of the insulation film  44 , and in the portion between the dotted lines in FIG. 15, that is, in the intermediate portion of the grooves  15 , by cutting the multilayered body  42 , a piezoelectric resonator  10 ′ shown in FIG. 16 is formed. 
     In comparison with the piezoelectric resonator  10  shown in FIG. 1, in the piezoelectric resonator  10 ′ shown in FIG. 16, the overlapping portions  46  of the insulation film  44  remain on both sides of the groove  15 . However, since the internal electrodes  36  ( 14 ) are not completely insulated in the overlapping portion  46 , the internal electrodes  36  ( 14 ) do not cause a connection failure. As a result, the piezoelectric resonator  10 ′ becomes similar to the piezoelectric resonator  10  shown in FIG. 1, and has similar functions. 
     In the above-described method which is a preferred embodiment of the present invention, when the width of the piezoelectric resonator is denoted as W, the width of the groove is denoted as a, and the width of the overlapping portion  46  of the insulation film  44  is denoted as x, 0&lt;x&lt;(W−a)/2 is preferably satisfied. Therefore, even if the position at which the groove  15  is formed in the multilayered body  42  is deviated by ½ or more of the edge thickness of the dicing machine, it is not deviated completely from the overlapping portion  46  of the insulation film  44 , as shown, for example, in FIG.  17 . In this case, in a piezoelectric resonator  10 ″ to be formed, as shown in FIG. 18, the overlapping portions  46  of the insulation film  44  are left on one side of the groove  15 . However, the internal electrodes  36  ( 14 ) are not completely insulated in the overlapping portion  46 , the internal electrodes  36  ( 14 ) are exposed on the other side of the base  12 , and the internal electrodes  36  ( 14 ) do not cause a connection failure. As a result, the piezoelectric resonator  10 ″ becomes substantially the same as the piezoelectric resonator  10  shown in FIG. 1, and has similar functions. 
     Therefore, in the above-described method which is a preferred embodiment of the present invention, even if the position at which the groove  15  is formed is slightly deviated from a predetermined position (the approximately central portion along a direction that is substantially parallel to the internal electrodes of the overlapping portions of the insulation film), a short-circuit does not occur between the electrodes, and it is easy to manufacture a surface-mountable piezoelectric resonator of a multilayered structure with a high yield of non-defective products. 
     When, as shown in FIG. 19, the groove  15  is formed alongside the overlapping portion  46  of the insulation film  44 , if the dimension x of the overlapping portion  46  is (W−a)/2 or more, the internal electrodes  36  ( 14 ) are completely insulated in the overlapping portions  46 , as shown in FIG.  20 . 
     Even in such a case, if the dimension x of the overlapping portion  46  of the insulation film  44  is set such that 0&lt;x&lt;(W−a)/2, the internal electrodes  36  ( 14 ) are not insulated completely. 
     Also in preferred embodiments of the present invention, if the thickness a of the edge for forming the groove  15  is formed to be larger than the width x of the overlapping portion  46  of the insulation film  44 , in the case where the groove  15  is formed at a predetermined position, it is possible to obtain a piezoelectric resonator  10  having no overlapping portion  46  of the insulation film  44 . In such a case, even if the groove  15  is formed at a position that is deviated slightly from a predetermined desired position, it is possible to obtain a piezoelectric resonator  10  having no overlapping portion  46  of the insulation film  44 . 
     By using the above-described piezoelectric resonator  10 , an electronic component, such as an oscillator and a discriminator, is manufactured. FIG. 21 is a perspective view showing an example of an electronic component  60 . The electronic component  60  includes an insulator substrate  62 . Two recesses  64  are formed in each of the opposing end portions of the insulator substrate  62 . Two pattern electrodes  66  and  68  are disposed on one main surface of the insulator substrate  62 . One of the pattern electrodes  66  is formed between the opposing recesses  64  in a substantially L-shaped configuration from one end of the recess toward the approximate central portion of the insulator substrate  62 . Also, the other pattern electrode  68  is formed between the other opposing recesses  64  in a substantially L-shaped configuration from the other end of the recess toward the approximately central portion of the insulator substrate  62 . Then, near the central portion of the insulator substrate  62 , the two pattern electrodes  66  and  68  are arranged so as to be opposite to each other and spaced from each other. The pattern electrodes  66  and  68  are arranged to extend around from the end portion of the insulator substrate  62  toward the other surface. 
     As shown in FIG. 22, a support member  24  made of a conductive material, disposed at each of the approximate central portions of the external electrodes  20  and  22  of the piezoelectric resonator  10 , is connected by, for example, a conductive bonding agent to the end portion of the pattern electrode  66  and the pattern electrode  68  in the approximate central portion of the insulator substrate  62 . As a result, the external electrodes  20  and  22  of the piezoelectric resonator  10  are fixed onto the insulator substrate  62  and also electrically connected to the pattern electrodes  66  and  68 . 
     Furthermore, a metal cap  74  is put on the insulator substrate  62 . At this time, an insulating resin is coated onto the insulator substrate  62  and the pattern electrodes  66  and  68  so that the metal cap  74  is not electrically connected to the pattern electrodes  66  and  68 . Then, as a result of the metal cap  74  being mounted, the electronic component  60  is completed. In this electronic component  60 , the pattern electrodes  66  and  68  formed in such a manner as to extend around from the end portion of the insulator substrate  62  toward the rear surface are used as input and output terminals for connection with an external circuit. 
     In this electronic component  60 , since the piezoelectric resonator  10  is supported by the support member  24  located at the approximate central portion along the length direction of the base  12 , the end portion of the piezoelectric resonator  10  is located separated and spaced from the insulator substrate  62 , thereby allowing for free and unhindered vibration. Also, the approximate central portion, which is a node of the piezoelectric resonator  10 , is fixed by the support member  24 , and the external electrodes  20  and  22  and the pattern electrodes  66  and  68  are electrically connected to each other. Since the support member  24  is formed in the piezoelectric resonator  10  in advance, accurate positioning at the node of the piezoelectric resonator  10  can be performed. Therefore, in comparison with a case in which a projection-shaped support member is formed on the side of the pattern electrodes  66  and  68  and the piezoelectric resonator is mounted thereon, it is possible to support the node with accuracy. Therefore, leakage of vibration of the piezoelectric resonator  10  is prevented and excellent resonator characteristics are obtained. Also, the need to use a lead wire for connecting the external electrodes  20  and  22  of the piezoelectric resonator  10  to the pattern electrodes  66  and  68  is eliminated, and the electronic component  60  can be manufactured at a low cost. 
     Furthermore, this electronic component  60 , together with ICs and the like, may be mounted in a circuit substrate, and may be used as an oscillator and a discriminator. Since the electronic component  60  of such a construction is hermetically sealed and protected by the metal cap  74 , this component can be used as a chip component which can be mounted by reflow soldering or the like. 
     In the case where this electronic component  60  is used as an oscillator, since the above-described piezoelectric resonator  10  is used, spurious emissions are minimized, and abnormal vibrations caused by spurious emissions are prevented. Also, since the capacitance value of the piezoelectric resonator  10  can be set freely, it is easy to achieve impedance matching with an external circuit. In particular, when the component is used as an oscillation element for a voltage-controlled oscillator, since ΔF of the resonator is large, it is possible to obtain a wider variable frequency range than was previously possible. 
     When this electronic component  60  is used as a discriminator, the feature that ΔF of the resonator is large leads to the feature that peak separation is wide. Furthermore, since the capacitance design range of the resonator is wide, it is easy to achieve impedance matching with an external circuit. 
     Furthermore, use of a plurality of piezoelectric resonators  10  makes it possible to manufacture a ladder filter. FIG. 23 is a plan view of the essential portion showing an example of an electronic component used as a ladder filter having a ladder-type circuit. FIG. 24 is an exploded perspective view of the essential portion thereof. In the electronic component  60  shown in FIGS. 23 and 24, four pattern electrodes  90 ,  92 ,  94 , and  96  are disposed on the insulator substrate  62 . Five lands disposed in one row and spaced from each other are disposed on these pattern electrodes  90  to  96 . In this case, a first land from one end of the insulator substrate  62  is formed in the pattern electrode  90 , a second land and a fifth land are formed in the pattern electrode  92 , a third land is formed in the pattern electrode  94 , and a fourth is formed in the pattern electrode  96 . 
     The support member  24  disposed on the external electrodes  20  and  22  of the respective piezoelectric resonators  10   a ,  10   b ,  10   c , and  10   d  is mounted on these lands. In this case, in order to construct the ladder-type circuit shown in FIG. 25, the piezoelectric resonators  10   a  to  10   d  are mounted. Then, a metal cap (not shown) is put onto the insulator substrate  62 . 
     This electronic component  60  is used as a ladder filter having a ladder-type circuit, such as that shown in FIG.  25 . At this time, for example, two piezoelectric resonators  10   a  and  10   d  are used as series resonators and the other two piezoelectric resonators  10   b  and  10   c  are used as parallel resonators. Such a ladder filter is designed so that the capacitance of the parallel resonators  10   b  and  10   c  exceeds the capacitance of the series resonators  10   a  and  10   d.    
     The attenuation of the ladder filter depends upon the capacitance ratio of the series resonator to the parallel resonator. In this electronic component  60 , by varying the number of multilayers of the piezoelectric resonators  10   a  to  10   d , the capacitance can be adjusted. Therefore, by adjusting the capacitance of the piezoelectric resonators  10   a  to  10   d , it is possible to realize a ladder filter having a larger attenuation with a smaller number of resonators than in a case in which a conventional piezoelectric resonator utilizing a transverse piezoelectric effect is used. Also, since ΔF of the piezoelectric resonators  10   a  to  10   d  is larger than that of the conventional piezoelectric resonator, it is possible to realize a ladder filter having a wider passing bandwidth than that using a conventional piezoelectric resonator. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the forgoing and other changes in form and details may be made therein without departing from the spirit of the invention.