JP2009272795A - Piezoelectric vibration element, and piezoelectric device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration element in which a connection state of a conductive adhesive is easily confirmed and its adhesive strength is enhanced. <P>SOLUTION: The piezoelectric vibration element has a crystal substrate 2, driven electrodes 3 and 4 formed on both principal surfaces of a crystal substrate 2, two pad electrodes 6 and 8 formed on one surface of the crystal substrate 2, and a through-hole 9 formed on the pad electrode 6, wherein the driven electrode 4 is disposed on the linear extension connecting the two pad electrodes 6 and 8, the through-hole 9 is formed on the pad electrode 6 disposed between the pad electrode 8 and driven electrode 4, the electrode pad 8 is connected to the driven electrode 4 through a lead electrode 7, the electrode pad 6 is connected to the driven electrode 4 through a lead electrode 5 and the through-hole 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a piezoelectric vibration element, a piezoelectric device, and a manufacturing method thereof, and is particularly suitable for improving the adhesive strength of a conductive adhesive.

While mobile communication devices such as mobile phones are becoming smaller and lighter, there is a strong demand for higher functionality, and there are two conflicting demands for increasing the number of parts and miniaturization associated with higher functionality. In order to satisfy them simultaneously, importance is attached to the effective use of the board area by reducing the area of the printed circuit board constituting the electrical component and increasing the density of mounted components. Quartz resonators (vibrators, filters) used as frequency control devices in mobile communication devices and transmission communication devices are also strongly required to be miniaturized. As a device package structure to support high-density mounting, The surface mount type has become the mainstream, and at the same time, there is an increasing demand for higher frequencies.
FIG. 7 is a perspective view of a conventional AT-cut quartz crystal vibrating element disclosed in Patent Document 1.
The crystal resonator element 110 shown in FIG. 7 is a vibrator using the fundamental thickness shear vibration wave of an AT-cut crystal substrate, and one main surface of the crystal substrate constituting the crystal resonator element 110 is recessed by etching. Thus, the recess 113 is formed. Therefore, this quartz substrate has a structure in which the bottom surface of the recessed portion 113 is an ultrathin vibrating portion 113a and the outer periphery of the vibrating portion 113a is integrally supported by the thick annular surrounding portion 114 over the entire circumference. It has become.
Further, gold is deposited using a mask, or a main surface electrode 111 constituting an excitation electrode is formed on one main surface (vibration portion 113a) of the quartz substrate by photolithography, and a lead electrode extending therefrom. In addition to 115 and the pad electrode 116, a pad electrode 117 is formed. The pad electrode 117 is a back electrode 1 constituting an excitation electrode formed in the same manner on the other main surface.
The lead electrode 118 extending from 12 is electrically connected to the lead electrode 118 by pulling out to the surface side through the side end face of the quartz substrate. If the crystal resonator element 110 is configured as described above,
A vibration device that is less affected by the supporting stress can be realized.
As another prior document, for the purpose of increasing the bonding strength of the quartz substrate, a crystal resonator is disclosed in which through holes are provided in the outer periphery of the chip to ensure conduction between the front and back sides (
Patent Document 2).
Moreover, in order to ensure the electrode connection with the support member, a piezoelectric device is disclosed in which a through hole is provided in the quartz plate of the lead electrode portion (Patent Document 3).
JP 2002-246869 A JP 2004-173050 A JP-A-8-018389

By the way, when a piezoelectric device such as a crystal resonator is configured using the crystal resonator element 110 disclosed in Patent Document 1, the pad electrodes 116 and 117 of the crystal resonator element 110 are connected to the inner bottom surface of a surface mount package (not shown). The upper conductive pad was connected using a conductive adhesive.
However, in the conventional crystal resonator element 110 shown in FIG. 7, the connection state of the pad electrode 116 on the side close to the vibrating portion 113a is obstructed by the metal film of the pad electrode 116, and the connection state can be confirmed visually. There was a problem that it was not possible.
Further, the conventional piezoelectric device using the crystal resonator element 110 has a problem in that the bonding strength is weak because the connection between the conductive pads of the surface mount package (not shown) and the pad electrodes 116 and 117 is flat.
The present invention has been made in view of the above points, and it is easy to check the connection state of the conductive adhesive and can increase the adhesive strength of the conductive adhesive. An object is to provide a device and a manufacturing method thereof.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A piezoelectric substrate, an excitation electrode formed on both main surfaces of the piezoelectric substrate, and two pad electrodes formed on one side of the piezoelectric substrate are connected to each other. The excitation electrode is disposed on a straight extension line, and the through-hole is provided in a pad electrode provided at a position close to the excitation electrode of the two pad electrodes, and the pad electrode is connected to the through-hole and the lead electrode. And a piezoelectric vibration element in which the other pad electrode is connected to the other excitation electrode via a lead electrode.

If comprised in this way, when connecting two pad electrodes to a connection electrode using a conductive adhesive, a throwing effect will be acquired by the conductive adhesive which flowed into the conductive adhesive with which the through-hole was filled. Therefore, the adhesive strength between the connection electrode and the pad electrode by the conductive adhesive can be improved.
In addition, by forming a through hole in the other pad electrode located between the one pad electrode and the excitation electrode, it is possible to confirm the connection state of the conductive adhesive visually from above. is there.

Application Example 2 The piezoelectric vibration element according to Application Example 1 is characterized in that the excitation electrodes formed on both main surfaces of the piezoelectric substrate have different areas.

According to this configuration, even if the positions of the excitation electrodes formed on both main surfaces are slightly shifted, the area where the excitation electrodes face does not change, so that there is no variation in characteristics.

Application Example 3 Application Example 1 or 2 in which the pattern width of the lead electrode is as narrow as possible than the pattern width of the pad electrode, and the lead electrode is formed along the longitudinal end of the quartz substrate.
The piezoelectric vibration element described in the above is characterized.

If comprised in this way, the energy leak of thickness shear vibration can be suppressed as much as possible.

[Application Example 4] The piezoelectric vibration element according to Application Example 1 or 2 and a package substrate on which two connection electrodes are formed, and in the state in which a conductive adhesive is filled in the through hole, The piezoelectric device is characterized in that two pad electrodes and the two connection electrodes are connected by a conductive adhesive.

With this configuration, it becomes possible to reliably fill the inside of the through hole with the conductive adhesive, and the anchoring effect is obtained by the conductive adhesive flowing into the conductive adhesive filled in the through hole. Therefore, the adhesive strength between the connection electrode and the pad electrode can be improved.

Application Example 5 The area of the excitation electrode formed on the lower surface side of the piezoelectric substrate on which the pad electrode is formed is smaller than the area of the excitation electrode formed on the upper surface side of the piezoelectric substrate, and the piezoelectric substrate The piezoelectric device according to Application Example 3, wherein a diameter of the conductive adhesive applied to the through hole on the upper surface side of the piezoelectric substrate is smaller than a diameter of the conductive adhesive applied to the lower surface side of the piezoelectric substrate. And

If comprised in this way, it can prevent that the other pad electrode with which the conductive adhesive was apply | coated, and the excitation electrode are short-circuited.

[Application Example 6] The method for manufacturing a piezoelectric device according to Application Example 3 or 4, wherein a first application step of applying a conductive adhesive to a connection electrode to which the piezoelectric vibration element is connected; A mounting step of mounting a piezoelectric vibration element on the connection electrode coated with an adhesive, a second application step of applying a conductive adhesive to the through hole of the piezoelectric vibration element from the upper surface side, and the first and second And a drying step of drying the conductive adhesive after the coating step.

  In this way, the piezoelectric device of the present invention can be manufactured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams showing a configuration of a piezoelectric vibration element according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA shown in FIG.
In the piezoelectric vibration element 1 shown in FIG. 1, excitation electrodes 3 and 4 are formed on both front and back main surfaces of a rectangular crystal substrate 2. The excitation electrode 3 on the upper surface (front surface) side is electrically connected to the pad electrode 6 formed on the rear surface side through the lead electrode 5 and the through hole 9. The excitation electrode 4 on the lower surface (back surface) side is electrically connected to the pad electrode 8 via the lead electrode 7. The excitation electrodes 3 and 4, the lead electrodes 5 and 7, and the pad electrodes 6 and 8 are patterned using a photolithographic technique after forming an electrode film on the surface of the quartz substrate 2 by sputtering or vapor deposition of an electrode material. Can be formed.
One pad electrode 8 is formed near the end of the quartz substrate 2 in the short direction. The other pad electrode 6 is formed between the pad electrode 8 and the excitation electrode 4. In other words, the piezoelectric vibration element 1 of the present embodiment has the excitation electrode 4 on the straight extended game connecting the two pad electrodes 6 and 8.
Is trying to place.
The pad electrode 6 is formed with a through-hole 9 having conductivity, and the excitation electrode 3 is formed on the quartz substrate 2.
Are connected to the pad electrode 6 on the back surface side through a lead electrode 5 and a through hole 9 extending from the excitation electrode 3 on the front surface side.

FIG. 2 is a cross-sectional view of a piezoelectric vibrator configured using the piezoelectric vibration element of the present embodiment shown in FIG.
In the piezoelectric vibrator 10 shown in FIG. 2, for example, a metal lid 20 is joined to an upper portion of a package substrate 11 formed in a concave shape by laminating ceramics. External terminals 14 and 14 are provided on the outer bottom surface of the package substrate 11. The external terminals 14 and 14 are conductive pads (on the inner bottom surface of the package substrate 11 via internal conductors (not shown) in the package substrate 11).
Connection electrode) 12 and the like.
The conductive pads 12 and 12 are connected to the pad electrode 6 of the piezoelectric vibration element 1 via the conductive adhesive 13.
8 is electrically and mechanically connected. Further, in the present embodiment, the conductive adhesive 13 is also applied to the upper surface side of the piezoelectric vibration element 1 with respect to the pad electrode 6 in which the through hole 9 is formed.
With this configuration, the conductive adhesive 13 that flows into the through-hole 9 from the lower surface side of the piezoelectric vibration element 1 and the conductive adhesive 13 that flows into the through-hole 9 from the upper surface side of the piezoelectric vibration element 1 are formed. It combines and hardens in the through hole 9. As a result, a throwing effect (anchor effect) is obtained in which the conductive adhesive 13 in the through hole 9 acts like a nail or wedge, so that the adhesive strength between the conductive pad 12 of the package substrate 11 and the pad electrodes 6 and 8 is obtained. Can be improved.
Conventionally, when the other pad electrode 6 is formed between the one pad electrode 8 and the excitation electrode 4, the metal film of the other pad electrode 6 becomes an obstacle, and the connection state of the pad electrode 6 is changed to the upper side. In this embodiment, the through hole 9 is formed in the pad electrode 6 so that the connection state of the conductive adhesive 13 is confirmed by visual observation from above. There is an advantage that becomes possible.

Further, when the conductive adhesive 13 is applied to the upper surface side and the lower surface side of the piezoelectric vibration element 1 as in this embodiment, the conductive adhesion on the lower surface side of the piezoelectric vibration element 1 is caused by its own weight or the like. The application diameter of the agent 13 is larger than the application diameter of the conductive adhesive 13 on the upper surface side. For this reason, in this embodiment, the area of the excitation electrode 4 formed on the lower surface side of the piezoelectric vibration element 1 is made smaller than the area of the excitation electrode 3 formed on the upper surface side. As a result, the pad electrode 6 and the excitation electrode 4 are short-circuited by increasing the distance between the conductive adhesive 13 applied between the pad electrode 6 and the conductive pad 12 of the package substrate 11 and the excitation electrode 4. Can be prevented. Of course, when the diameter of the conductive adhesive on the lower surface side is smaller than the diameter of the conductive adhesive on the upper surface side, the same is true when the area of the excitation electrode formed on the upper surface side is smaller than the area of the excitation electrode formed on the lower surface side. An effect is obtained.
In addition, the excitation electrodes 3 and 4 formed on both main surfaces of the piezoelectric vibration element 1 as in the present embodiment.
For example, when the excitation electrodes 3 and 4 are formed, even if the positions of the excitation electrodes 3 and 4 are slightly shifted, the area where the excitation electrodes 3 and 4 are opposed does not change. There is also an advantage that no variation occurs.
Further, in the piezoelectric vibration element 1 of the present embodiment, energy leakage of thickness shear vibration is likely to occur in the crystal X-axis direction, so that the pattern width of the lead electrodes 5 and 7 extending from the excitation electrodes 3 and 4 is made as narrow as possible. In addition, since the lead electrodes 5 and 7 are formed along the longitudinal ends of the quartz substrate 2, energy leakage due to thickness-shear vibration can be suppressed as much as possible.
In the present embodiment, the case where the through hole 9 is formed only in one of the pad electrodes 6 of the piezoelectric vibration element 1 has been described as an example. However, this is only an example, and the two pad electrodes 6, 8 are described.
You may form the through-hole 9 in both. However, when the through holes 9 are formed in the two pad electrodes 6 and 8, it is necessary to increase the spacing between the pad electrodes 6 and 8 in order to ensure the strength of the crystal substrate 2. From this point of view, it is preferable to form the through hole 9 only in one of the pad electrodes 6.

FIG. 3 is a diagram showing another configuration of the piezoelectric vibration element according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same site | part as FIG. 1, and detailed description is abbreviate | omitted. The piezoelectric vibration element 1 shown in FIG. 3 is configured such that the lead electrode 5 connecting the excitation electrode 3 and the pad electrode 6 is drawn from the center of the excitation electrode 3. Even in such a configuration, the same effect as in FIG. 1 can be obtained. However, from the viewpoint of confining the thickness shear vibration energy, the configuration shown in FIG. 1 is preferable.

4A and 4B are diagrams illustrating the configuration of the piezoelectric vibration element according to the second embodiment, in which FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along line BB illustrated in FIG. In addition, the same code | symbol is attached | subjected to the same site | part as FIG. 1, and detailed description is abbreviate | omitted.
The piezoelectric vibration element 1 shown in FIG. 4 is a so-called reverse mesa type piezoelectric vibration element having an ultrathin portion in order to increase the vibration frequency. That is, the concave portion 31 is formed on one main surface of the quartz substrate 2 by etching, and the bottom surface of the concave portion 31 is an ultrathin vibrating portion 31a. That is, this quartz crystal substrate 2 has a configuration in which the bottom surface of the recessed portion 31 is an ultrathin vibrating portion 31a and the outer periphery of the vibrating portion 31a is integrally supported by a thick annular surrounding portion 32 over the entire circumference. It has become. And the excitation electrode 4 is formed in this vibration part 31a. Even in such a configuration, the same effect as in FIG. 1 can be obtained. Further, there is an advantage that high frequency can be achieved.
In the present embodiment, the quartz resonator element is described as an example of the piezoelectric resonator element of the present invention. However, this is only an example, and the present invention can be applied to a piezoelectric substrate other than the quartz substrate.
In this embodiment, a piezoelectric vibrator has been described as an example of a piezoelectric device to which the piezoelectric vibration element of the present invention is applied. However, the piezoelectric vibration element of the present invention is an MCF (Monolithic Cryst).
al Filters), piezoelectric oscillators, and piezoelectric modules.
In the present embodiment, a flat metal lid 20 is formed on the upper surface of the package substrate 11 having a recess.
The piezoelectric vibration element 1 is hermetically sealed by bonding, but the structure of the package substrate 11 is merely an example. For example, conductive pads 12 and 12 are provided on the upper surface of a flat package substrate (insulating substrate), The present invention can also be applied to the case where the piezoelectric vibrating element 1 is mounted on the conductive pads 12 and 12 and a metal lid having a reverse saddle shape (reverse concave shape) is joined and hermetically sealed.
In the present embodiment, the pad electrodes 6 are formed on the upper surface side and the lower surface side of the through hole 9. However, this is merely an example, and the excitation electrode 3 is connected to the conductive pad via the lead electrode 5 and the through hole 9. 12, the pad electrode 6 provided on the same side as the excitation electrode 3 may be omitted, and only the pad electrode 6 on the same side as the excitation electrode 4 may be provided. Further, the pad electrodes 6 provided on both surfaces of the quartz substrate 2 can be omitted. However, in order to improve the conduction between the excitation electrode 3 and the conduction pad 12, at least the pad electrode on the lower surface side of the quartz substrate 2 is used. 6 is preferably provided.

FIG. 5 is a diagram illustrating a manufacturing process of a piezoelectric vibrator using the piezoelectric vibration element according to the present embodiment.
In this case, first, as the first coating process, the conductive pads 12, 1 of the package substrate 11.
A conductive adhesive 13 is applied on the substrate 2 (S1). Next, as a mounting process, the conductive adhesive 13
The quartz crystal substrate 2 is mounted on the conductive pads 12 and 12 coated with (S2). Next, as a second application step, the conductive adhesive 13 is applied from the upper side of the pad electrode 6 of the quartz substrate 2 in which the through hole 9 is formed (S3). Thereafter, as a drying step, the conductive adhesive 13 is dried (S4).
According to such a manufacturing process, the conductive adhesive 13 applied to the lower side of the quartz substrate 2 and the conductive adhesive 13 applied to the upper side can be simultaneously dried in the drying step. The conductive adhesive 13 that has flowed into the through hole 9 from the lower surface side and the conductive adhesive 13 that has flowed into the through hole 9 from the upper surface side can be reliably combined in the through hole 9.

FIG. 6 is a diagram showing a manufacturing process in the case of manufacturing the piezoelectric vibrator of the present embodiment using the conventional manufacturing process as a comparison with the manufacturing process of the present embodiment shown in FIG.
In this case, first, as the first coating process, the conductive pads 12, 1 of the package substrate 11.
A conductive adhesive 13 is applied on the substrate 2 (S1). Next, as a mounting process, the conductive adhesive 13
The quartz crystal substrate 2 is mounted on the conductive pads 12 and 12 coated with (S2). Next, as a first drying step, the conductive adhesive 13 is dried (S4).
Next, as a second application step, the conductive adhesive 13 is applied from the upper side of the pad electrode 6 of the quartz substrate 2 in which the through hole 9 is formed (S4). Thereafter, as a second drying step, the conductive adhesive 13 is dried (S5).
In this case, in the first and second drying steps, the conductive adhesive 13 applied to the lower side of the quartz substrate 2 and the conductive adhesive 13 applied to the upper side of the quartz substrate 2 are separately dried. Therefore, there is a possibility that the conductive adhesive 13 cannot be reliably connected in the through hole 9, and therefore the manufacturing process of the present embodiment shown in FIG. 5 is preferable.

It is the figure which showed the structure of the piezoelectric vibration element which concerns on embodiment of this invention, (a) is a top view, (b) is AA sectional drawing shown to (a). It is sectional drawing of the piezoelectric vibrator to which the piezoelectric vibration element of this embodiment is applied. It is the figure which showed the other structure of the piezoelectric vibration element concerning this Embodiment. It is the figure which showed the structure of the piezoelectric vibration element concerning 2nd Embodiment. It is the figure which showed the manufacturing process of the piezoelectric vibrator using the piezoelectric vibration element concerning this embodiment. It is the figure which showed the manufacturing process in the case of manufacturing the piezoelectric vibrator of this embodiment using the conventional manufacturing process. It is a perspective view of the conventional AT cut crystal resonator element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibration element, 2 ... Quartz substrate, 3, 4 ... Excitation electrode, 5, 7 ... Lead electrode, 6, 8 ... Pad electrode, 9 ... Through-hole, 10 ... Piezoelectric vibrator, 11 ... Package substrate, 12 ... Conductive pads,
13 ... conductive adhesive, 14 ... external terminal, 20 ... metal lid, 31 ... concave part, 31a ... vibrating part,
32 ... Annular Go

Claims (6)

A piezoelectric substrate, an excitation electrode formed on both main surfaces of the piezoelectric substrate, and two pad electrodes formed on one side of the piezoelectric substrate, on a straight extension line connecting the two pad electrodes The excitation electrode is disposed, and the through hole is provided in a pad electrode provided at a position close to the excitation electrode among the two pad electrodes, and the pad electrode is connected to the one of the one through the through hole and the lead electrode. A piezoelectric vibration element characterized in that it is connected to an excitation electrode and the other pad electrode is connected to the other excitation electrode via a lead electrode. 2. The areas of excitation electrodes formed on both main surfaces of the piezoelectric substrate are different.
The piezoelectric vibration element described in 1. The pattern width of the lead electrode is as narrow as possible than the pattern width of the pad electrode, and the lead electrode is formed along an end portion in the longitudinal direction of the quartz substrate. Piezoelectric vibration element. The piezoelectric vibration element according to claim 1 or 2 and a package substrate on which two connection electrodes are formed, and the two pad electrodes are filled with a conductive adhesive inside the through hole. A piezoelectric device characterized in that the two connection electrodes are connected to each other by a conductive adhesive. The area of the excitation electrode formed on the lower surface side of the piezoelectric substrate on which the pad electrode is formed,
The area of the excitation electrode formed on the upper surface side of the piezoelectric substrate is smaller, and the diameter of the conductive adhesive applied on the through hole on the upper surface side of the piezoelectric substrate is smaller than the lower surface side of the piezoelectric substrate. The piezoelectric device according to claim 4, wherein the piezoelectric device is smaller than a diameter of the applied conductive adhesive. A method for manufacturing a piezoelectric device according to claim 4 or 5,
A first application step of applying a conductive adhesive to a connection electrode to which the piezoelectric vibration element is connected;
A mounting step of mounting a piezoelectric vibration element on the connection electrode coated with the conductive adhesive;
A second application step of applying a conductive adhesive from the upper surface side to the through hole of the piezoelectric vibration element;
A drying step of drying the conductive adhesive after the first and second coating steps;
A method for manufacturing a piezoelectric device comprising:

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