JP2002118440A - Piezoelectric transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the mass-productivity of an electrodeless piezoelectric transducer with a sandwich construction comprising an electrodeless piezoelectric board with a mesa part as a vibrator at a center, and two piezoelectric boards with electrodes which are bonded integrally to both the upper and lower sides of the electrodeless piezoelectric board, while a distance between an excitation electrode and the mesa part is maintained constant with a high precision. SOLUTION: This piezoelectric transducer comprises an electrodeless piezoelectric board 22 which has at least a mesa part 30 as a vibrator, thin parts 31, and a thick support 32 linked integrally with the respective edges of the mesa part via the respective thin parts, and two piezoelectric boards 23 and 24 with electrodes which are bonded and fixed to both the upper and lower sides of the electrodeless piezoelectric board, respectively. The respective piezoelectric boards with electrodes have excitation electrodes 37 facing the upper and lower surfaces of the mesa part and lead 37a extended from one side edges of the respective excitation electrodes. Adhesive coating recesses 33 are formed respectively in the upper and lower surfaces of the outer edge of the thick support, and the respective recesses are filled with conductive adhesive to connect the respective recesses with the ends of the piezoelectric boards with electrodes including the lead electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in the structure of a piezoelectric vibrator using an electrodeless piezoelectric substrate having a mesa structure.

[0002]

2. Description of the Related Art Conventionally, a quartz vibrating element in which opposing excitation electrodes are attached to two main surfaces of a quartz substrate formed in a required shape is used so as to obtain a resonance frequency inversely proportional to the thickness of the quartz substrate. 2. Description of the Related Art Quartz resonators excited by thickness-shear mode vibration are used as frequency signal sources for various devices. In particular, a crystal unit using an AT-cut crystal substrate has extremely stable temperature characteristics over a wide temperature range.
Because of its excellent aging characteristics, it is widely used in various communication devices mainly for mobile communication. However, in the conventional quartz vibrating element in which the excitation electrode is formed on the quartz substrate, the excitation electrode is formed directly on the quartz substrate by vapor deposition or the like. Therefore, a vibrator having an electrodeless structure that does not have such an effect is used for an oscillator that requires high stability.

[First Conventional Example] Next, a conventional electrodeless AT
The structure of the cut crystal resonator will be described with reference to the external perspective views and the CC cross-sectional views shown in FIGS. The conventional electrodeless AT-cut crystal resonator 1 shown in FIG. 1 includes an electrodeless crystal substrate 2 and two electrode-attached crystal substrates 3 bonded and integrated on the upper and lower surfaces of the electrodeless crystal substrate 2, respectively. 4). First, the electrodeless quartz substrate 2
A mesa section 10 as a vibrating section located at a central portion, thin sections 11 continuously provided on two opposing edges of the mesa section 10, and a mesa section 10 via each of the thin sections 11. And a thick-walled support portion 12 which is connected and integrated with both end edges of the electrodeless crystal substrate for exciting thickness-shear vibration. Each of the electrode-added crystal substrates 3 and 4 has an excitation electrode 17 formed on an inner bottom surface of a recess 15 formed on a central inner surface facing the upper and lower surfaces of the mesa portion 10 of the electrodeless crystal substrate 2, respectively, and a recess 15. And a lead electrode 17a extending from the excitation electrode 17 to one end edge (thick portion 16) of each of the substrates 3 and 4. Each recess 15 formed in each of the electrode-attached crystal substrates 3 and 4 is provided to maintain a predetermined gap G between the upper and lower surfaces of the opposing mesa unit 10. This gap G is formed by the thick supporting portion 12 of the electrodeless quartz substrate 2.
When the conductive adhesive 18 is used to join the upper and lower surfaces and the thick portions 16 of the electrode-attached quartz substrates 3 and 4 with the conductive adhesive 18, the adhesive 18 is uniformly set to have a constant interval. Secured. The crystal resonator completed by sandwiching and bonding the electrodeless crystal substrate 2 between the electrode-attached crystal substrates 3 and 4 in this manner is mounted in a ceramic package (not shown) using a conductive adhesive, and is used for a long time. It is common to fill with a nitrogen gas for maintaining stability and to make it a closed state. Alternatively, there is also known a type in which external electrodes electrically connected to the excitation electrodes 17 are provided on the lower surface of the lower electrode-attached crystal substrate 4 and are directly mounted on a printed circuit board (not shown). However, the conventional electrodeless crystal resonator 1 configured as described above includes upper and lower surfaces of the thick support portion 12 of the electrodeless crystal substrate 2 and inner surfaces of the thick portions 16 of the electrode-added crystal substrates 3 and 4. And the gap G between the mesa unit 10 as a vibrating part and the upper and lower electrodes is kept constant due to a variation in the amount of the conductive adhesive to be used. However, variations in equivalent circuit constants occur due to variations in intervals, and this has been a factor in reducing the yield when mass-producing electrodeless crystal resonators having equivalent equivalent circuit constants. It should be noted that the correlation between the value of the gap G between the mesa unit 10 and the upper and lower excitation electrodes 17 and the deviation of the equivalent circuit constant is equivalent since the parallel capacitance corresponds to about ± 1 pF with respect to the spacing of about ± 1 μm. The variation of the circuit constant is about 10%. This variation rate is a great variation compared to the variation rate of about 1% of an ordinary quartz oscillator, and it is very difficult to improve this variation in view of the limitation of the conductive adhesive application amount control technology. is there. Thus, in the AT-cut crystal resonator having the electrodeless structure, the mesa unit 10 and the upper and lower excitation electrodes 1 are formed.
Despite the fact that it is important to keep the distance to the gap constant, it is very difficult to secure mass productivity while controlling this distance within an allowable range, and there is a defect that the yield is significantly deteriorated. .

[Second Conventional Example] Next, FIG. 10 is a cross-sectional view showing another conventional example of an electrodeless crystal resonator. This electrodeless piezoelectric resonator 1 includes an electrodeless crystal substrate 2 and an electrodeless crystal substrate 2. It has a sandwich shape composed of two electrode-attached quartz substrates 3 and 4 which are respectively joined and integrated on the upper and lower surfaces of the electrodeless quartz substrate 2. First, the electrodeless crystal substrate 2 has a thickness-shear vibration having at least a thick-walled mesa portion 10 as a vibrating portion located at the center portion, and thin-walled portions 11 respectively connected to both end edges of the mesa portion 10. Is an electrodeless quartz substrate that excites. Each of the electrode-added crystal substrates 3 and 4 has an excitation electrode 17 formed on an inner bottom surface of a recess 15 formed on a central inner surface facing the upper and lower surfaces of the mesa portion 10 of the electrodeless crystal substrate 2, respectively, and a recess 15. From the thick portion 16 located outside the substrate and the excitation electrode 17 to each substrate 3,
Lead electrode 17a extending to one edge (thick portion 16)
And The upper and lower electrode-attached crystal substrates 3 and 4 are joined and integrated by a conductive adhesive in a state where the inner surface of the thick portion 16 is in contact with the upper and lower surfaces of the thin portion 11, respectively. The electrodeless crystal resonator 1 is configured such that the electrode material is not directly deposited on the mesa portion 10 serving as a vibrating portion, but is excited via the gap G by the excitation electrodes 17 disposed on both sides of the mesa portion 10. Vibrator. As a method of forming the excitation electrodes 17 in the recesses 15 of the upper and lower quartz substrates 3 and 4, respectively, first, as shown in FIG.
After forming a plurality of recesses 15 on one surface of 4A by etching, the crystal substrate base materials 3A, 4A are cut into individual chips 3a, 4a by dicing along cutting lines L,
It is known that the chips 3a and 4a are individually packed in a plating gauge (not shown) and then the excitation electrode 17 and the lead electrode 17a are formed by plating.

Further, as shown in FIG. 11B, after forming a plurality of recesses 15 on one side of the base materials 3A, 4A of the quartz substrate by etching, the base material 3A of the quartz substrate 3 is subjected to batch processing.
A method is known in which an excitation electrode 17 and a lead electrode 17a are collectively formed at predetermined positions on A and 4A, respectively, and then cut into individual chips 3a and 4a by dicing along a cutting line L. In particular, the excitation electrode 1 shown in FIG.
As for the method of cutting the chips 3a and 4a individually into the plating gauges after forming the chip 7 and the like, the method of cutting the chips 17a and 4a individually into the plating gauge is omitted, and the electrodes 17a and 4a are provided at predetermined positions on each chip.
Etc. can be formed accurately. However, when the electrodes 17 and the like are formed on the substrate base materials 3A and 4A and then individually cut by dicing, as shown in FIG. 11B, the electrodes are formed on the side surfaces (cut surfaces) of the divided chips. Since the conductive adhesive 19 is not formed, conduction failure with the external terminal 6 such as a printed circuit board is easily caused by using the conductive adhesive 19 as shown in FIG.

[Third conventional example] Next, FIGS. 12 (a) and 12 (b)
1 is a cross-sectional view illustrating another conventional example of an electrodeless crystal resonator. This electrodeless piezoelectric resonator 1 includes an electrodeless crystal substrate 2 and
It has a sandwich shape composed of two electrode-attached crystal substrates 3 and 4 joined and integrated respectively on the upper and lower surfaces of the electrodeless crystal substrate 2. First, the electrodeless quartz substrate 2 includes a mesa section 10 as a vibrating section located at the center, and the mesa section 1.
0 is a non-electrode crystal substrate for exciting thickness-shear vibration, comprising at least thin portions 11 continuously provided at both end edges. Each of the electrode-added crystal substrates 3 and 4 has an excitation electrode 17 formed on an inner bottom surface of a recess 15 formed on a central inner surface facing the upper and lower surfaces of the mesa portion 10 of the electrodeless crystal substrate 2, respectively, and a recess 15. And a lead electrode 17a extending from the excitation electrode 17 to one end edge (the thick portion 16) of each of the substrates 3 and 4. The upper and lower two electrode-attached crystal substrates 3 and 4 are fixed with the clip 7 as shown in FIG. 12A with the inner surface of the thick portion 16 being in contact with the upper and lower surfaces of the thin portion 11, respectively. Alternatively, as shown in FIG. 12B, the thin portion 11 and the inner surface of the thick portion 16 are joined and integrated by the conductive adhesive 8. This electrodeless crystal resonator 1
Is a structure in which the electrode material is not directly deposited on the mesa portion 10 serving as the vibrating portion, and the excitation electrodes 17 disposed on both sides of the mesa portion 10 are opposed to each other.
Is an electrodeless piezoelectric vibrator that is excited through the gap G. These electrodeless crystal resonators 1 are electrically connected to the external electrodes 6 of the printed circuit board P using a conductive adhesive 19. However, the clip 7 as shown in FIG.
The fixing method using the method has a problem that the number of steps for assembling the clip increases, and the number of parts increases by the amount of the clip, and there is a problem in terms of productivity and cost. In addition, since a part of the clip protrudes up and down, there is a problem that the installation stability when mounting on the printed circuit board P is reduced.

The electrodeless piezoelectric substrate 1 according to the conventional example shown in FIG. 12B has a structure in which the opposing surfaces of the outer peripheral edges of the substrates 2, 3, and 4 are fixed using a conductive adhesive 8. But adhesive 8
Since the thickness of the gap G after drying is very small, the gap G is widened by the thickness. Also,
Since the thickness of the adhesive 8 itself is not uniform and varies, the gap of the gap G also varies. As an experiment, as a result of examining the expansion of the gap G after bonding using a silicone-based or epoxy-based adhesive, the value was +10 to 30 μm for the silicone-based and +5 to 10 μm for the epoxy-based. In order to suppress the spread of the gap G, a method of putting a weight on the upper surface of the piezoelectric vibrator and pressing the piezoelectric vibrator may be considered. In this case, since the adhesive widely spreads on the interface, a small vibrator is required. The result was not suitable. Since the equivalent constant of the electrodeless vibrator depends on the gap G, even when an epoxy adhesive that reduces the error of the gap G is used, the value of the equivalent constant Rl is 5.
There was a large spread of 0-100G. Thus, in order to obtain a vibrator having uniform characteristics, it is apparent that it is necessary to suppress variations in the gap G.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional electrodeless piezoelectric vibrator. An electrodeless piezoelectric substrate having a mesa portion as a vibrating portion,
An electrodeless piezoelectric vibrator having a sandwich shape composed of two piezoelectric substrates with electrodes which are respectively joined and integrated on the upper and lower surfaces of the electrodeless piezoelectric substrate. Another object of the present invention is to provide an electrodeless piezoelectric vibrator capable of ensuring mass productivity while maintaining a constant distance between the electrode and the mesa. The problem corresponding to the second conventional example is that, in the manufacturing process of the conventional electrodeless vibrator,
When a plurality of excitation electrodes are formed on a base material of a piezoelectric substrate by batch processing, conduction failure between an excitation electrode and an external electrode is suppressed, thereby reducing the equivalent resistance of the vibrator. It is in. A problem corresponding to the third conventional example is that an electrodeless piezoelectric substrate having a mesa portion as a vibrating portion in the center portion,
An electrodeless piezoelectric vibrator having a sandwich shape composed of two electrode-attached piezoelectric substrates that are respectively joined and integrated on the upper and lower surfaces of the electrodeless piezoelectric substrate. To provide an electrodeless piezoelectric vibrator that can ensure mass productivity while maintaining a constant distance between the excitation electrode formed on each electrode-attached piezoelectric substrate and the mesa portion accurately without using the same. is there. That is, when the electrodeless piezoelectric substrate and the piezoelectric substrate with electrodes on the front and back are fixed by using an adhesive, the variation in the air gap between the two is reduced, and thereby, the equivalent constant error of the vibrator is suppressed. Aim. Another object of the present invention is to provide a process for manufacturing an electrodeless vibrator according to a third conventional example, after joining a piezoelectric substrate with electrodes to one surface of an electrodeless piezoelectric substrate, turning the front and back sides upside down, and then turning the other surface to the other surface. Another object of the present invention is to eliminate the complicated process of bonding another piezoelectric substrate with electrodes to simplify the process and increase the productivity.

[0009]

According to a first aspect of the present invention, there is provided a mesa portion as a vibrating portion, and a thin portion connected to two opposing edges of the mesa portion. When,
An electrodeless piezoelectric substrate that excites a thickness-shear vibration, comprising: at least a thick supporting portion that is provided integrally with each edge of the mesa portion through each of the thin portions; A piezoelectric substrate with two electrodes, each of which is bonded and fixed to both sides,
A piezoelectric vibrator comprising: each of the electrode-attached piezoelectric substrates, excitation electrodes formed respectively on the inner bottom surface of the recess formed on the inner surface facing the upper and lower surfaces of the mesa portion of the electrodeless piezoelectric substrate,
And a lead electrode extending from one end of each excitation electrode toward one end of the electrode-less piezoelectric substrate. By filling a conductive adhesive in each of the adhesive application concave portions, each adhesive application concave portion is joined to an end of the electrode-attached piezoelectric substrate including the lead electrode. . The invention according to claim 2 is an electrodeless piezoelectric substrate that excites thickness-shear vibration, comprising at least a mesa portion as a vibrating portion and thin portions respectively connected to two opposing edges of the mesa portion. And two piezoelectric substrates with electrodes that are respectively bonded and fixed to the upper and lower surfaces of the electrodeless piezoelectric substrate, wherein each of the piezoelectric substrates with electrodes is a mesa of the electrodeless piezoelectric substrate. An excitation electrode formed on the inner bottom surface of the recess formed on the inner surface facing the upper and lower surfaces of the portion, a thick portion connected to two opposing edges of the recess, A lead electrode extending toward one edge of the thick portion, wherein the inner surface of the thick portion of the piezoelectric substrate with electrodes is bonded and fixed to the upper and lower surfaces of the thin portion of the electrodeless piezoelectric substrate, respectively. Forming a recess at the inner surface edge of the thick portion; Wherein the exposed and coated with a metal film forming the lead electrode to the wall.

According to a third aspect of the present invention, there is provided a method for exciting thickness-shear vibration, comprising at least a mesa portion as a vibrating portion and thin portions respectively connected to two opposing edges of the mesa portion. A piezoelectric vibrator comprising: an electrode piezoelectric substrate; and two electrode-attached piezoelectric substrates that are respectively bonded and fixed to upper and lower surfaces of the electrodeless piezoelectric substrate. An excitation electrode formed on an inner bottom surface of a recess formed on an inner surface facing the upper and lower surfaces of the mesa portion of the substrate, a thick portion connected to two opposing edges of the recess, A lead electrode extending from the electrode to one end edge of the thick portion, wherein the inner surface of the thick portion of the electrode-attached piezoelectric substrate is bonded and fixed to upper and lower surfaces of the thin portion of the electrodeless piezoelectric substrate, respectively. On the other end edge opposite to the one end edge from which The electrode piezoelectric substrate is set to be larger than the upper and lower electrode-attached piezoelectric substrates, and is formed along the other end of the electrodeless piezoelectric substrate and each step formed between the other end of each electrode-attached piezoelectric substrate. An adhesive is applied between the substrates to fix them. The invention of claim 4 is characterized in that an epoxy adhesive is used as the adhesive. The invention of claim 5 is an electrodeless piezoelectric substrate that excites thickness-shear vibration, comprising at least a mesa portion as a vibrating portion and thin portions respectively connected to two opposing edges of the mesa portion. And two piezoelectric substrates with electrodes that are respectively bonded and fixed to the upper and lower surfaces of the electrodeless piezoelectric substrate, wherein each of the piezoelectric substrates with electrodes is a mesa of the electrodeless piezoelectric substrate. An excitation electrode formed on the inner bottom surface of the recess formed on the inner surface facing the upper and lower surfaces of the portion, a thick portion connected to two opposing edges of the recess, A lead electrode extending toward one end edge of the thick portion, and wherein the inner surface of the thick portion of the piezoelectric substrate with an electrode is adhesively fixed to the upper and lower surfaces of the thin portion of the electrodeless piezoelectric substrate, and the lead electrode is drawn out. At the other end opposite to the one end, the lower electrode In the order of the electric substrate, the electrodeless piezoelectric substrate, and the upper electrode-equipped piezoelectric substrate, the dimensions are set so that the length of each other end is gradually reduced. A characteristic feature is that an adhesive is applied along between the substrates to fix them. The invention according to claim 6 is characterized in that the electrodeless piezoelectric substrate and the electrode-attached piezoelectric substrate are each formed of an AT-cut quartz substrate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. [First Embodiment] FIGS. 1A and 1B are a plan view and a cross-sectional view taken along the line BB, respectively, showing a configuration of an electrodeless AT-cut quartz resonator according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of an electrodeless AT-cut quartz resonator. In FIG. 2, only the upper electrode-attached crystal substrate is shown upside down. The electrodeless piezoelectric vibrator 21 is, for example, an AT-cut crystal vibrator. The electrodeless piezoelectric vibrator 21 includes an electrodeless crystal substrate 22 and two electrode-attached crystal substrates 23 bonded and integrated on the upper and lower surfaces of the electrodeless crystal substrate 22, respectively. 24. First, the electrodeless quartz substrate 22 includes a mesa unit 30 as a vibrating unit located at the center, and a mesa unit 30.
Thin portions 31 respectively connected to two opposing edges of
And a thick supporting portion 32 integrally connected to both end edges of the mesa portion 30 via the thin portions 31, and concave portions (adhesion portions) on upper and lower surfaces of a central portion of an outer edge of the thick supporting portion 32, respectively. Support plate 33 formed by forming an agent application concave portion 33
a) is an electrodeless quartz substrate that excites thickness-shear vibration, at least comprising: The crystal substrates 23 and 24 with electrodes are
Excitation electrodes 37 formed on the inner bottom surface of a recess 35 formed on a central inner surface facing the upper and lower surfaces of the mesa portion 30 of the electrodeless quartz substrate 22, respectively, and thick portions 36 located on both outer sides of the recess 35 And a recess (adhesive application recess) 38 formed at the center of the inner surface along the outer edge of each thick portion 36, and one edge (thick wall) of each of the substrates 23 and 24 from the excitation electrode 37. Part 3
6) and a lead electrode 37a that covers the inner wall and the like of one of the recesses 38. The planar shape of the thick supporting portion 32 and the planar shape of each thick portion 36 are the same, and they are configured to come into surface contact with each other when these surfaces are joined. Are formed in the same shape and the same positional relationship so as to communicate with each other. The excitation electrode 3 is provided on the other concave portion 38 and the thick portion 36 side.
7 is covered with an independent metal film 37b that does not conduct. The metal film 37b is for adjusting the balance with the thickness of the one concave portion 38 and the thick portion 36 on which the lead electrode 37a is formed. However, the metal film 37b is not indispensable, and even if it is not present, no major trouble occurs.

Each recess 35 formed in each of the electrode-attached quartz substrates 23 and 24 is provided to maintain a predetermined gap G between the upper and lower surfaces of the opposing mesa unit 30. This gap G is formed when the conductive adhesive 39 joins the upper and lower surfaces of the thin support plate 33 a in the recessed portion 33 of the electrodeless quartz substrate 22 and the recessed portion 38 of each of the electrode-attached quartz substrates 23 and 24. Instead of being determined depending on the applied thickness of the adhesive 39,
The upper and lower surfaces 32a of the thick supporting portion 32 of the electrodeless quartz substrate 22,
It is determined by the surface contact between the electrode 32b and the inner surface 36a of the thick portion 36 of each of the electrode-added crystal substrates 23 and 24. Therefore,
The upper and lower surfaces 32a of the thick supporting portion 32 of the electrodeless quartz substrate 22,
32b and the processing accuracy such as the height accuracy of the inner side surface 36a of the thick portion 36 of each of the electrode-added crystal substrates 23 and 24 is ensured.
The interval can always be kept constant. Thus, the electrodeless crystal substrate 2 is placed between the electrode-added crystal substrates 23 and 24.
2 is sandwiched, and the quartz oscillator completed by bonding the recesses 33 and 38 is mounted in a ceramic package (not shown) using a conductive adhesive, and nitrogen gas for maintaining long-term stability. And sealed.
The exploded perspective view of FIG. 3 is a modified example of the electrodeless crystal resonator of FIG. 2. The electrodeless crystal substrate 22 of this embodiment has a mesa portion 30 located at the center of the substrate. 32
The configuration surrounded by is different from the examples of FIGS. Further, the crystal substrates with electrodes 23 and 24 shown in FIG. 3 are different from the examples shown in FIGS. 1 and 2 in that the entire periphery of the excitation electrode 37 is surrounded by an annular thick portion 36. This type of electrodeless crystal resonator has upper and lower surfaces of the mesa unit 30 and each of the recesses 3.
Since the gaps G formed between the first and second members 5 are substantially airtight spaces, they can be used as they are for surface mounting without being mounted on a ceramic package or the like. That is, it is possible to provide an external electrode that is electrically connected to each of the excitation electrodes 37 on the lower surface of the lower electrode-attached quartz substrate 24 and directly mount it on a printed board (not shown).

FIG. 4 is a cross-sectional view of a main part showing a state where the electrodeless crystal resonator 21 is mounted on the bottom plate on the inner bottom surface of the ceramic package or on the printed circuit board with the conductive adhesive 40. In manufacturing the electrodeless crystal resonator having the above-described configuration, first, regarding the electrodeless crystal substrate 22, when forming the mesa portion 30, the thin portion 31, the thick support portion 32, and the like by etching or the like. Since the recesses 33 can be manufactured collectively, there is no fear that the number of manufacturing steps is increased as compared with the conventional case. That is, only by making the mask used for etching a shape having an opening at a position corresponding to the concave portion 33, an electrodeless quartz substrate having a desired shape can be obtained without increasing the number of steps.

[Second Embodiment] FIGS. 5A, 5B and 5C are plan views of an electrodeless piezoelectric vibrator according to an embodiment of the present invention corresponding to the second conventional example. It is an A sectional view and a BB sectional view, and this electrodeless piezoelectric vibrator 51 is, for example, an electrodeless AT-cut crystal vibrator.
It has a sandwich structure composed of two electrode-attached quartz substrates 53 and 54 that are joined and integrated on the upper and lower surfaces of the electrodeless quartz substrate 52, respectively. First, the electrodeless quartz substrate 5
2 is a mesa unit 60 as a vibrating unit located at the center,
A thin-walled portion 61 continuously provided at each end edge of the mesa portion 60;
Is an electrodeless quartz substrate that excites thickness-shear vibration at least. Each of the electrode-attached quartz substrates 53 and 54 has an excitation electrode 67 formed on the inner bottom surface of a recess 65 formed on a central inner side surface facing the upper and lower surfaces of the mesa portion 60 of the electrodeless quartz substrate 52, respectively. A thick portion 66 located outside the
And a lead electrode 67a extending from the excitation electrode 67 to one end edge (thick portion 66) of each of the substrates 53 and 54. The lead direction of each lead electrode 67a is the same direction. The electrode-attached crystal substrates 53 and 54 are joined to the electrodeless crystal substrate 52 with respect to the upper and lower surfaces of the thin portion 61, respectively.
This is performed by bonding the inner side surfaces of the thick portions 66 of the third and the fourth portions 54 with a conductive adhesive. This electrodeless quartz oscillator 51
Is a non-electrode piezoelectric vibrator that excites via a gap G by each of the excitation electrodes 67 disposed opposite to the front and back sides of the mesa portion 60 without directly depositing (metallizing) the electrode material on the mesa portion 60 as a vibrating portion. is there. The characteristic structure of the electrodeless crystal resonator 51 is that the exposed areas of the lead electrodes 67a are formed by forming the recesses 68 at the edges of the electrode-attached crystal substrates 53 and 54 on the side from which the lead electrodes 67a are drawn out. Is set widely. That is, a recess 68 similar to the recess 38 shown in FIGS. 2 and 3 is formed at the center of the end on the inner side surface of the electrode-added crystal substrates 53 and 54 of this embodiment.
The entire inner wall of the recess 68 is covered with a metal film constituting the lead electrode 67a. Therefore, the electrodeless crystal resonator 51
When the electrode-attached quartz substrates 53 and 54 are bonded and fixed to both the front and back sides, the covering surface of the lead electrode 67a is exposed to the outside via the recess 68, and the printed circuit board P using the conductive adhesive 69. A sufficient conductive area can be ensured even when connecting to the upper external electrode 70. Note that the upper lead electrode 67a and the lower lead electrode 67a have their plane directions shifted forward and backward and do not overlap. Can be connected. If the lead electrodes 67a to be pulled out from the excitation electrodes 67 of the electrode-attached crystal substrates 53 and 54 are drawn in different directions, the electrode-attached crystal substrate 5 corresponding to the terminal end of each lead electrode 67a is used.
A concave portion 68 is formed at the edge of each of the concave portions 3 and 54 to form the concave portion 68.
After exposing the electrode film inside, the external electrodes 70 at the corresponding positions may be fixed with a conductive adhesive. Therefore, the lead-out direction of each lead electrode 67a is not limited to the same direction.

The electrode-attached quartz substrates 53 and 54 having the above-described structure are placed in a procedure as shown in FIG. 11B (after forming an electrode film at a required position on the quartz substrate base material by batch processing). In the case of manufacturing by cutting into individual pieces), the shape of the crystal substrate base material after etching is as shown in FIG. At the time of etching, a mask having an additional opening for forming the concave portion 38 may be used as a mask to be used. Since the mask can be formed simultaneously with the concave portion 65, the number of steps does not increase. Since the depth of the recess 38 is equivalent to the depth of the recess 65 and is sufficient, batch etching using the same mask is possible. After the metal film is collectively formed on the crystal substrate base material that has been etched in this manner by vapor deposition using a predetermined mask, the metal film is divided along the cutting line L, thereby forming a concave portion at the edge. A piece with 38 can be obtained. Since the obtained individual pieces of the crystal substrates with electrodes 53 and 54 are coated with a metal film (lead electrode) up to the inner wall of the recess 38, they were applied to an electrodeless crystal resonator having a configuration as shown in FIG. In this case, it is easy to ensure conduction with the external electrode.

[Third Embodiment] FIG. 7A is a cross-sectional view showing the structure of an electrodeless piezoelectric vibrator according to an embodiment of the present invention corresponding to a third conventional example (A in FIG. 5A). -(B) is a cross-sectional view showing a modified example thereof. The electrodeless piezoelectric vibrator 81 is, for example, an electrodeless AT-cut crystal vibrator, and includes an electrodeless crystal substrate 82 and two electrode-attached crystal bonded to the upper and lower surfaces of the electrodeless crystal substrate 82, respectively. A sandwich structure including substrates 83 and 84 is provided. First, the electrodeless crystal substrate 82 has a thickness slip provided at least including a thick-walled mesa portion 90 as a vibrating portion located at the center portion, and thin-walled portions 91 respectively connected to both end edges of the mesa portion 90. An electrodeless quartz substrate that excites vibration.
Each of the electrode-added quartz substrates 83 and 84 has an excitation electrode 97 formed on the inner bottom surface of a recess 95 formed on a central inner side surface facing the upper and lower surfaces of the mesa portion 90 of the electrodeless quartz substrate 82, respectively. And a lead electrode 97a extending from the excitation electrode 97 to one end edge (thick portion 96) of each of the substrates 83 and 84. The lead-out direction of each lead electrode 97a is the same direction. This electrodeless crystal resonator 8
Reference numeral 1 denotes an electrodeless piezoelectric vibrator that does not directly deposit (metallize) an electrode material on the mesa portion 90 as a vibrating portion, and excites through the gap G by the respective excitation electrodes 97 disposed on both sides of the mesa portion 90 so as to face each other. It is. The characteristic configuration of the electrodeless piezoelectric vibrator 81 according to this embodiment is that the other end of the other end 82A of the electrodeless quartz substrate 82 (the end opposite to the one end from which each lead electrode 97a is drawn out). Edge) is set to be longer than each electrode-attached substrate edge 83A, 84A, and an adhesive 98 is applied along two steps formed by the other edge 82A, 83A, 84A. .

That is, the other end of the thin portion 91 of the electrodeless quartz substrate 82 is projected beyond the other end of each thick portion 96 of the upper and lower electrode-attached quartz substrates 83 and 84, and the electrodeless quartz substrate The width of the thin portion 91 at the other end 82A of the substrate 82 is set to such a degree that a step is formed between the thin portion 91 and the other end 84A. Set small so that a step is formed. With this configuration, steps are formed on both upper and lower surfaces of the projecting thin portion 91, and the substrates 82, 83, and 84 can be fixed by applying an adhesive 98 to the steps. Therefore, it is possible to solve the problem that the gap G is generated when the adhesive is interposed between the surfaces where the substrates are in contact with each other. Edges on the side from which the two lead electrodes 97a are drawn out are connected and fixed to the two external electrodes 70 on the printed circuit board 70 using a conductive adhesive 99, respectively. Note that the edges of each of the substrates 82, 83, 84 forming a step for applying the adhesive 98 are formed by a lead electrode 97.
The edge from which a is drawn may be selected. In this case,
It is preferable to use a conductive adhesive as the adhesive.

Next, FIG. 7B is a cross-sectional view showing a state in which each adhesive enters between the substrates 82, 83 and 84 while the adhesives 98 and 99 are being dried, and the gap G is enlarged. It is. Experimentally, using a silicone-based adhesive and an epoxy-based adhesive, respectively, as a result of examining the change in the gap G after bonding,
+1 to 3 μm for silicone type, +0 for epoxy type
There was a variation of 1.5 μm. Regardless of which adhesive is used, the adhesive enters the bonding surface between the substrates and the gap G, despite the adhesives 98 and 99 being applied to the positions shown in FIG. A phenomenon was seen in which the image was slightly enlarged. This is because the adhesive infiltrates between the substrates during drying of the adhesive, and separates the front and back crystal substrates with electrodes 83 and 84 from the electrodeless crystal substrate 82. However, particularly when an epoxy-based adhesive is used, the spread of the gap G is small, and as a result, the value of the equivalent constant Rl is 15 to 2
A vibrator having a small deviation of 5 G was able to be manufactured.
The reason why the silicone type is inferior to the epoxy type is the viscosity. It has been found that the higher the viscosity, the stronger the condensing force and the larger the gap G. When manufacturing this type of electrodeless crystal resonator 81, as shown in FIG. 7 (c), after positioning and mounting the electrode-attached crystal substrate 83 on the upper surface of the electrodeless crystal substrate 82, the conductive adhesive 98 is applied. After the coating and drying, it is necessary to turn over the quartz substrate 84 with the electrodes and then position and mount the electrode-attached quartz substrate 84 on the electrodeless quartz substrate 82 before applying the adhesive 88. Thus, there is a problem in that the number of manufacturing steps and the manufacturing time are increased by the time required to turn the adhesive upside down and the time required to wait for the adhesive applied on one side to dry, thereby lowering the productivity.

[Fourth Embodiment] FIG. 8A shows a configuration of an electrodeless piezoelectric vibrator according to an embodiment (fourth embodiment) of the present invention which can solve the disadvantages of the third embodiment. (Corresponding to the AA section in FIG. 5 (a)), and FIGS. 5 (b) and 5 (c) are sectional views showing the manufacturing procedure. The electrodeless piezoelectric vibrator 81 is, for example, an electrodeless AT-cut quartz vibrator,
An electrodeless crystal substrate 82 and two electrode-attached crystal substrates 8 bonded and integrated to the upper and lower surfaces of the electrodeless crystal substrate 82, respectively.
3 and 84.
First, the electrodeless crystal substrate 82 has a thickness slip provided at least including a thick-walled mesa portion 90 as a vibrating portion located at the center portion, and thin-walled portions 91 respectively connected to both end edges of the mesa portion 90. An electrodeless quartz substrate that excites vibration. Each of the electrode-added crystal substrates 83 and 84 is a mesa 9 of the electrodeless crystal substrate 82.
Recesses 9 formed in the central inner surface opposing the upper and lower surfaces 0, respectively.
Excitation electrodes 97 formed on the inner bottom surface of the substrate 5, a thick portion 96 located outside the recess 95, and a lead electrode extending from the excitation electrode 97 to one edge (thick portion 96) of each of the substrates 83 and 84. 97a. The lead-out direction of each lead electrode 97a is the same direction. The electrodeless crystal resonator 81 does not directly deposit (metallize) the electrode material on the mesa section 90 as the vibrating section, but is excited via the gap G by the respective excitation electrodes 97 arranged on both sides of the mesa section 90. Electrodeless piezoelectric vibrator. The characteristic configuration of the electrodeless piezoelectric vibrator 81 according to this embodiment is opposite to the other ends 82A, 83A, 84A of the substrates 82, 83, 84, that is, the one end on the side from which the lead electrodes 97a are drawn out. , Each substrate edge 82A,
83A and 84A, the length of the other end 84 increases from the lower substrate 84 to the upper substrates 82 and 83 in order.
A, 82A, and 83A are configured to be sequentially shortened. In addition, the lower substrate 8 is sequentially arranged from the upper substrate 83.
2 and 84, the other end edges 83A, 82A, 84A
May be set so as to become shorter in sequence, but in the present embodiment, description will be made mainly on the illustrated example. That is, the width of the thick portion 96 on the other end 84A side of the lowermost electrode-attached crystal substrate 84 is set large, and the width of the thin portion 91 of the other end 82A of the electrodeless crystal substrate 82 is the same as the other end 84A. The width of the other end 93 </ b> A of the electrode-attached quartz substrate 83 is set small enough to form a step with the thin portion 91. With this configuration, steps are formed on the upper surfaces of the substrate edges 82A and 83A, respectively, and the substrates 98, 83, and 84 can be fixed by applying the adhesive 98 to the steps. . Here, the step portion or the step is a space formed between an upper surface (or a lower surface) of one substrate and a side wall of another substrate located immediately above (or immediately below). That is, it refers to the intersection of two surfaces.

8 (b) and 8 (c) are sectional views showing an assembly procedure (adhesion procedure) of the electrodeless piezoelectric vibrator 81.
As shown in (b), an electrodeless quartz substrate 82 is placed on a lower electrode-attached quartz substrate 84, and at this time, both quartz substrates 82, 84
The adhesive 98 is applied along the step formed by the other ends 82A and 84A of the other end. Next, without waiting for the adhesive to dry, the upper electrode-attached quartz substrate 83 is positioned and placed on the upper surface of the electrodeless quartz substrate 82 as shown in FIG. , 83A is applied with an adhesive 98 along the steps formed. In the electrodeless piezoelectric vibrator according to this embodiment, when the upper and lower surfaces of the electrodeless quartz substrate 82 are joined in a sandwich manner by the electrode-attached quartz substrates 83 and 84, one end edges 82A, 83A, and 8 of the respective substrates.
Since the protrusion length of 4A is set so as to gradually decrease from the lower side to the upper side, the edges 84A, 82 of the substrates 84, 82
Steps for applying the adhesive can be formed on the upper surface of A, respectively. Therefore, the adhesive 98 is attached to the step between the edge 84A of the lower substrate 84 and the edge 82A of the substrate 82 at the intermediate position.
, And after positioning the upper substrate 83 on the substrate 82, the respective substrates 82A, 83A, 83A
The operation of applying the adhesive 98 to the step formed on the substrate can be performed continuously, and the cumbersome operation of turning over the two joined substrates is unnecessary. For this reason, productivity can be improved significantly. In addition, the edge from which the lead electrode 97a is drawn may be selected as the edge of each of the substrates 82, 83, and 84 that forms the step portion for applying the adhesive 98. In this case, it is preferable to use a conductive adhesive as the adhesive.

[0021]

As described above, according to the present invention, an electrodeless piezoelectric substrate provided with a mesa portion as a vibrating portion in the center portion, and the upper and lower surfaces of the electrodeless piezoelectric substrate are respectively joined and integrated. In a non-electrode piezoelectric vibrator having a sandwich shape composed of a plurality of piezoelectric substrates with electrodes, the excitation electrodes formed on each of the piezoelectric substrates with electrodes, while maintaining a constant distance between the mesa portion with high accuracy, An electrodeless piezoelectric vibrator capable of securing mass productivity can be provided. That is, the piezoelectric vibrator according to the first embodiment can be put in place by simply changing the shape of the etching external pattern mask that forms the gap for applying the adhesive without changing the conventional manufacturing process. Since a gap for adhesive application can be formed, a remarkable effect is exerted in mass-producing an electrodeless AT-cut quartz resonator having little variation in equivalent circuit constant values while maintaining other characteristics. The piezoelectric vibrator according to the second embodiment is characterized in that, when a plurality of excitation electrodes are formed on a base material of a piezoelectric substrate by batch processing in a conventional process of manufacturing an electrodeless vibrator, an excitation electrode and an external electrode are formed. Can be suppressed, and thereby the equivalent resistance of the vibrator can be reduced. The piezoelectric vibrator according to the third embodiment includes an electrodeless piezoelectric substrate having a mesa portion as a vibrating portion in the center, and two electrodes joined and integrated on the upper and lower surfaces of the electrodeless piezoelectric substrate, respectively. In the electrodeless piezoelectric vibrator provided with the sandwich-shaped piezoelectric substrate, without using a clip or the like to fix between the substrates, the excitation electrode formed on each electrode-mounted piezoelectric substrate, and the mesa portion It is possible to provide an electrodeless piezoelectric vibrator capable of ensuring mass productivity while maintaining a constant interval between the electrodes. That is, when the electrodeless piezoelectric substrate and the piezoelectric substrate with electrodes on the front and back sides are fixed by using an adhesive, the variation of the air gap between the two is reduced, thereby suppressing the equivalent constant error of the vibrator. it can. Another embodiment of the present invention relates to a process for manufacturing an electrodeless vibrator according to the third embodiment, in which a piezoelectric substrate with electrodes is joined to one surface of an electrodeless piezoelectric substrate, and then the other side is turned over. An object of the present invention is to eliminate the complicated step of joining another piezoelectric substrate with an electrode to a surface, simplify the process, and increase the productivity.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view showing a configuration of an electrodeless AT-cut quartz resonator according to an embodiment of the present invention, and BB.
Sectional view.

FIG. 2 is an exploded perspective view of an electrodeless AT-cut quartz resonator.

FIG. 3 is an exploded perspective view according to a modification of the electrodeless crystal resonator of FIG. 2;

FIG. 4 is an essential part cross-sectional view showing a state in which an electrodeless crystal resonator is mounted on a bottom plate on the inner bottom surface of the ceramic package or on a printed circuit board using a conductive adhesive.

5A is a plan view of an electrodeless piezoelectric vibrator according to an embodiment corresponding to the second conventional example, FIG. 5B is a cross-sectional view taken along line AA, and FIG. 5C is a cross-sectional view taken along line BB.

FIG. 6 is a diagram showing a shape of a quartz substrate base material after etching.

7A is a cross-sectional view illustrating a configuration of an electrodeless piezoelectric vibrator according to an embodiment of the present invention corresponding to a third conventional example, FIG. 7B is a cross-sectional view illustrating a modification thereof, and FIG. FIG.

FIG. 8A is a cross-sectional view showing a configuration of an electrodeless piezoelectric vibrator according to an embodiment (fourth embodiment) that can solve the disadvantage of the third embodiment, and FIGS. () Is a cross-sectional view showing the manufacturing procedure.

9A is an external view of a conventional electrodeless piezoelectric vibrator, and FIG. 9B is a cross-sectional view taken along the line CC.

FIG. 10 is a longitudinal sectional view of another conventional electrodeless piezoelectric vibrator.

FIGS. 11A and 11B are diagrams illustrating a conventional method of manufacturing a piezoelectric substrate.

12A and 12B are longitudinal sectional views of another conventional electrodeless piezoelectric vibrator.

[Explanation of symbols]

21 electrode-less AT-cut crystal oscillator, 22 electrode-less crystal substrate, 23, 24 crystal substrate with electrodes, 30 mesa section, 3
1 thin portion, 32 thick support portion, upper and lower surfaces of 32a, 32b, 33 recess (adhesive application recess), 33a thin support plate, 35 recess, 36 thick portion, 37 excitation electrode,
37a lead electrode, 37b metal film, 38 recess,
39 conductive adhesive, 40 conductive adhesive, 51 electrodeless piezoelectric vibrator, 52 electrodeless crystal substrate, 53, 54 electrode crystal substrate, 60 mesa portion, 61 thin portion, 65 concave portion, 66 thick portion, 67 Excitation electrode, 67a Lead electrode, 68 recess, 70 external electrode, 81 electrodeless piezoelectric vibrator, 82 electrodeless crystal substrate, 83, 84 crystal substrate with electrode, 82A, 83A, 84A substrate other edge, 90
Mesa section, 91 thin section, 95 concave section, 96 thick section, 9
7 Excitation electrode, 97a Lead electrode, 98 Conductive adhesive.

Claims (6)

[Claims] 1. A mesa portion as a vibrating portion, a thin portion connected to two opposing edges of the mesa portion, and a thin portion connected to each of the edges of the mesa portion via the thin portion. An electrodeless piezoelectric substrate having at least an integrated thick support portion for exciting thickness shear vibration; and two electrode-attached piezoelectric substrates adhered and fixed to upper and lower surfaces of the electrodeless piezoelectric substrate, respectively. Wherein each of the piezoelectric substrates with electrodes includes an excitation electrode formed on an inner bottom surface formed in a concave surface formed on an inner surface facing the upper and lower surfaces of the mesa portion of the electrodeless piezoelectric substrate. A lead electrode extending from the electrode to one end edge, wherein the adhesive-coated concave portions are formed on upper and lower surfaces of the outer edge of the thick support portion of the electrodeless piezoelectric substrate, respectively. Filling each adhesive coating recess with conductive adhesive allows each adhesive A piezoelectric vibrator, wherein a concave portion for applying an agent is joined to an end of a piezoelectric substrate with an electrode including the lead electrode. 2. An electrodeless piezoelectric substrate for exciting thickness shear vibration, comprising at least a mesa portion as a vibrating portion, and thin portions respectively connected to two opposing edges of the mesa portion, A piezoelectric substrate with two electrodes, each of which is bonded and fixed to both upper and lower surfaces of the electrodeless piezoelectric substrate, wherein each of the piezoelectric substrates with electrodes is a mesa portion of the electrodeless piezoelectric substrate. Excitation electrodes formed on the inner bottom surface of the recess formed on the inner surface opposing the upper and lower surfaces, a thick portion connected to two opposing edges of the recess, and a thick portion from each excitation electrode. A lead electrode extending toward one end of the electrodeless piezoelectric substrate, wherein an inner surface of a thick portion of the piezoelectric substrate with electrodes is bonded and fixed to upper and lower surfaces of a thin portion of the electrodeless piezoelectric substrate, respectively, wherein the lead electrode is formed. A concave portion is formed at an inner surface edge of the thick portion, and the concave portion is formed in the concave portion. The piezoelectric vibrator, characterized in that exposed by covering the metal film forming the lead electrode. 3. An electrodeless piezoelectric substrate for exciting a thickness shear vibration, comprising at least a mesa portion as a vibrating portion, and thin portions respectively connected to two opposing edges of the mesa portion, A piezoelectric substrate with two electrodes, each of which is bonded and fixed to both upper and lower surfaces of the electrodeless piezoelectric substrate, wherein each of the piezoelectric substrates with electrodes is a mesa portion of the electrodeless piezoelectric substrate. Excitation electrodes formed on the inner bottom surface of the recess formed on the inner surface opposing the upper and lower surfaces, a thick portion connected to two opposing edges of the recess, and a thick portion from each excitation electrode. A lead electrode extending toward one end of the piezoelectric substrate, wherein the inner surface of the thick portion of the piezoelectric substrate with electrodes is bonded and fixed to the upper and lower surfaces of the thin portion of the electrodeless piezoelectric substrate, respectively. On the other end edge opposite to Adhesive is applied along the steps formed between the other end of the electrodeless piezoelectric substrate and the other end of each piezoelectric substrate with electrodes. A piezoelectric vibrator characterized by fixing between the substrates. 4. The piezoelectric vibrator according to claim 3, wherein an epoxy-based adhesive is used as said adhesive. 5. An electrodeless piezoelectric substrate that excites thickness-shear vibration, comprising at least a mesa portion as a vibrating portion, and thin portions respectively connected to two opposing edges of the mesa portion, A piezoelectric substrate with two electrodes, each of which is bonded and fixed to both upper and lower surfaces of the electrodeless piezoelectric substrate, wherein each of the piezoelectric substrates with electrodes is a mesa portion of the electrodeless piezoelectric substrate. Excitation electrodes formed on the inner bottom surface of the recess formed on the inner surface opposing the upper and lower surfaces, a thick portion connected to two opposing edges of the recess, and a thick portion from each excitation electrode. A lead electrode extending toward one end of the piezoelectric substrate, wherein the inner surface of the thick portion of the piezoelectric substrate with electrodes is bonded and fixed to the upper and lower surfaces of the thin portion of the electrodeless piezoelectric substrate, respectively. At the other end opposite to the Substrate, electrodeless piezoelectric substrate,
And in the order of the upper piezoelectric substrate with electrodes, dimensions are set so that the length of each other end is gradually reduced, and an adhesive is applied along a step formed between the other ends of each substrate. A piezoelectric vibrator in which the substrates are fixed. 6. The piezoelectric device according to claim 1, wherein the electrodeless piezoelectric substrate and the piezoelectric substrate with electrodes are each formed of an AT-cut quartz substrate. Piezoelectric vibrator.