JP6117555B2 - Piezoelectric parts - Google Patents

Description

  The present invention relates to a piezoelectric component capable of obtaining highly reliable and highly accurate frequency characteristics.

  Conventionally, as shown in FIG. 8, a support substrate 61, and a piezoelectric element 63 having both ends fixed on the support substrate 61 with a conductive bonding material 62, an electrode 64 provided on the upper surface of the support substrate 61, and A resonator (piezoelectric component) in which a capacitor is formed by an electrode 65 provided on the lower surface to form a capacitor element is known (see Patent Document 1).

JP-A-2005-210404

  Such a resonator (piezoelectric component) is difficult to reduce in size because it is necessary to secure a region for forming a capacity on the support substrate 61. In addition, when trying to manufacture a large number of pieces, it is difficult to obtain a piezoelectric component that is adjusted by measuring the frequency with high accuracy by picking up the stray capacitance by the electrode of the adjacent piece.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric component that can be miniaturized and can be adjusted in frequency with high accuracy even by taking multiple pieces.

The piezoelectric component of the present invention includes a support substrate and a piezoelectric element having both ends fixed on the support substrate and mounted so as to vibrate. The piezoelectric element opposes one main surface and the other main surface, respectively. An electrode disposed so as to have a region, and is insulated from the electrode on the one main surface and the other main surface at a distance from each other and between the electrodes disposed on the opposite main surface And a capacitor forming electrode arranged so as to form a capacitor , wherein the electrode forming material and the capacitor forming electrode forming material are different from each other.

  The piezoelectric component according to the present invention is characterized in that the thickness of the electrode is different from the thickness of the capacitor forming electrode.

  The piezoelectric component of the present invention is characterized in that the surface of the capacitance forming electrode is covered with an insulating film.

  In the piezoelectric component according to the present invention, the distance between the electrode on the one main surface and the capacitor forming electrode is different from the distance between the electrode on the other main surface and the capacitor forming electrode. And

The piezoelectric component of the present invention is characterized in that the area of the capacitance forming electrode provided on the one main surface and the area of the capacitance forming electrode provided on the other main surface are different in plan view. And

  According to the present invention, stray capacitance due to the influence of adjacent wiring conductors can be suppressed in a multi-piece state before being divided into pieces, and the oscillation frequency of each piezoelectric component can be measured with high accuracy. Thereby, a large number of piezoelectric parts having high-accuracy frequency tolerance can be manufactured (mass produced), and a piezoelectric part whose frequency is adjusted with high precision at low cost can be obtained. Furthermore, according to the present invention, since it is not necessary to secure a region for forming a capacitance on the support substrate, the piezoelectric component can be miniaturized.

(A) is a schematic sectional drawing which shows an example of embodiment of the piezoelectric component of this invention, (b) is an enlarged view of the piezoelectric element shown to (a). (A) is a schematic top view of the state which removed the cover body of the piezoelectric component of Fig.1 (a), (b) is a top view of the support substrate shown to (a). (A) And (b) is a schematic sectional drawing which shows the other example of the piezoelectric element in embodiment of the piezoelectric component of this invention. It is the graph which evaluated the spurious characteristic of the piezoelectric component containing the piezoelectric element of the structure shown to Fig.3 (a). It is a schematic sectional drawing which shows the other example of embodiment of the piezoelectric component of this invention. It is a schematic sectional drawing which shows the other example of the piezoelectric element in embodiment of the piezoelectric component of this invention. (A) is a schematic sectional drawing which shows the other example of the piezoelectric element in embodiment of the piezoelectric component of this invention, (b) is a top view of the piezoelectric element shown to (a), (c) is (a). It is a bottom view of the piezoelectric element shown in FIG. (A) is a schematic plan view of a part (lid) omitted showing an example of a conventional piezoelectric component, and (b) is a schematic sectional view of the piezoelectric component shown in (a).

  An example of an embodiment of a piezoelectric component of the present invention will be described in detail with reference to the drawings.

  FIG. 1A is a schematic sectional view showing an example of an embodiment of the piezoelectric component of the present invention, and FIG. 1B is an enlarged view of the piezoelectric element shown in FIG. FIG. 2A is a schematic plan view of the piezoelectric component of FIG. 1A with the lid removed, and FIG. 2B is a plan view of the support substrate shown in FIG. .

  The piezoelectric component of the example shown in FIGS. 1 and 2 includes a support substrate 1 and a piezoelectric element 2 having both ends fixed on the support substrate 1 and capable of vibrating. The piezoelectric element 2 has one main surface and Provided with electrodes (excitation electrodes 22 and 23) disposed so as to have regions facing each other on the other main surface, and spaced apart from the electrodes (excitation electrodes 22 and 23) on the one main surface and the other main surface, respectively. Capacitor forming electrodes 24 and 25 are provided so as to form a capacitance with electrodes (excitation electrodes 22 and 23) which are insulated and are disposed on opposite main surfaces (excitation electrodes 22 and 23).

  The support substrate 1 includes, for example, a support substrate body 11 formed as a rectangular flat plate having a length of 2.5 mm to 7.5 mm, a width of 1.0 mm to 3.0 mm, and a thickness of 0.1 mm to 1 mm. It is out. As the support substrate body 11, a ceramic material such as alumina and a resin material such as glass epoxy can be used.

A pair of signal terminals 121, 122 and a ground terminal 13 are provided on the lower surface of the support substrate body 11 constituting the support substrate 1, and the pair of signal terminals 121, 122, Wiring conductors 141 and 142 are provided so as to be electrically connected, and a wiring conductor 143 is provided so as to be electrically connected to the ground terminal 13. These are formed by printing and sintering a conductive paste containing metal powder such as gold, silver, copper, aluminum, tungsten, or the like. Moreover, what formed plating, such as Ni / Au and Ni / Sn, may be used as needed.

  On the support substrate 1, the piezoelectric element 2 is mounted so that both ends are fixed. Specifically, both ends of the piezoelectric element 2 are fixed on the support substrate 1 by the conductive bonding material 3 so as to vibrate.

  The piezoelectric body 21 constituting the piezoelectric element 2 is formed, for example, as a rectangular flat plate having a length of 1.0 mm to 4.0 mm, a width of 0.2 mm to 2 mm, and a thickness of 40 μm to 1 mm. The material is polarized in the thickness direction. The piezoelectric body 21 is made of, for example, piezoelectric ceramics based on lead titanate, lead zirconate titanate, sodium niobate, potassium niobate, a bismuth layered compound, etc., or a piezoelectric single unit such as lithium tantalate or lithium niobate. It can be formed using crystals.

  In addition, the piezoelectric element 2 includes electrodes (excitation electrodes 22 and 23) arranged so as to have regions facing each other on one main surface and the other main surface of the piezoelectric body 21. The excitation electrode 22 provided on the upper main surface of the piezoelectric body 21 is provided so as to extend from one end portion toward the other end portion, and is provided on the lower main surface of the piezoelectric body 21. The excitation electrode 23 is provided so as to extend from the other end toward the one end, and has regions facing each other. The excitation electrodes 22 and 23 can be made of metal such as gold, silver, copper, and aluminum, and are applied to the surface of the piezoelectric body 21 to a thickness of, for example, 0.1 μm to 3 μm. The excitation electrode 22 of the piezoelectric element 2 is electrically connected to the wiring conductor 141 via the conductive bonding material 3, and the excitation electrode 23 of the piezoelectric element 2 is connected to the wiring conductor 142 via the conductive bonding material 3. And are electrically connected. The connection portion of the wiring conductor 141 with the conductive bonding material 3 and the connection portion of the wiring conductor 142 with the conductive bonding material 3 may be a pad-shaped pattern. In FIG. A connection portion with the conductive bonding material 3 is a pad-shaped pattern.

  Here, the conductive bonding material 3 also has a function of ensuring a predetermined space (gap) between the upper surface of the support substrate 1 and the lower surface of the piezoelectric element 2. As such a conductive bonding material 3, for example, solder, a conductive adhesive, or the like is used. As long as the solder is used, a lead-free material such as copper, tin, or silver can be used. If it is an adhesive agent, the epoxy-type conductive resin or silicone-type resin containing 75-95 mass% of electroconductive particles, such as silver, copper, and nickel, can be used.

  In such a piezoelectric element 2, when a voltage is applied between the excitation electrode 22 and the excitation electrode 23 from both ends, thickness longitudinal vibration or thickness slip occurs at a specific frequency in a region where the excitation electrode 22 and the excitation electrode 23 face each other. The piezoelectric vibration is generated.

  The piezoelectric element 2 is insulated from the electrodes (excitation electrodes 22 and 23) on the one main surface and the other main surface of the piezoelectric body 21 with a space therebetween, and is disposed on the main surface on the opposite side (excitation). Capacitor forming electrodes 24 and 25 are arranged so as to form a capacitor (capacitance element) between the electrodes 22 and 23). The capacitance forming electrode 24 and the capacitance forming electrode 25 of the piezoelectric element 2 are electrically connected to the wiring conductor 143 through the conductive bonding material 3. In addition, the connection part with each electroconductive joining material 3 in the wiring conductor 143 is a pad-shaped pattern.

  Capacitance forming electrodes 24 and 25 are arranged so as to form capacitors (capacitance elements) with electrodes (excitation electrodes 22 and 23) arranged on the main surface on the opposite side across the piezoelectric body 21. Thus, the dielectric properties of the piezoelectric body 21 can be used effectively.

  The capacitance forming electrodes 24 and 25 can be made of the same material as the excitation electrodes 22 and 23. Further, the capacitance obtained between the excitation electrode 22 and the capacitance forming electrode 24 and between the excitation electrode 23 and the capacitance forming electrode 25 is the IC of the oscillation circuit formed by being connected to the piezoelectric element 2. Determined by matching.

  A lid 4 is provided on the support substrate 1 so as to cover the piezoelectric element 2. The lid 4 is bonded to the peripheral edge of the upper surface of the support substrate 1 with an adhesive or the like, thereby causing the piezoelectric element 2 housed in the space formed together with the support substrate 1 to physically influence from the outside. And a function of protecting from chemical influences, and a hermetic sealing function for preventing entry of foreign matters such as water into the space formed together with the support substrate 1. In addition, as a material of the cover body 4, metal, such as SUS, ceramics, such as an alumina, resin, glass, etc. can be used, for example. Further, an insulating resin material such as an epoxy resin may contain an inorganic filler in a proportion of 25 to 80% by mass so as to reduce the difference in thermal expansion coefficient with the support substrate 1.

  The piezoelectric element 2 is insulated from the electrodes (excitation electrodes 22 and 23) disposed on the one main surface and the other main surface with a space therebetween, and the electrodes (excitation electrodes 22 and 22) disposed on the opposite main surface. 23) is provided with capacitance forming electrodes 24 and 25 arranged so as to form a capacitance (capacitance element) between the wiring conductors adjacent to each other in a multi-piece state before being separated into individual pieces. This makes it possible to suppress the influence of stray capacitance and accurately measure the oscillation frequency of each piezoelectric component. As a result, a large number of piezoelectric parts having an oscillation frequency tolerance with high accuracy can be manufactured (mass produced), and a piezoelectric part whose frequency is adjusted with high precision at low cost can be obtained.

  Furthermore, according to the present invention, it is not necessary to secure a region for forming a capacitance on the support substrate 1, so that the piezoelectric component can be miniaturized.

  Here, as shown in FIG. 3, the thickness t1 of the electrodes (excitation electrodes 22, 23) and the thickness t2 of the capacitance forming electrodes 24, 25 are preferably different. Thereby, since the thickness of the piezoelectric element 2 becomes non-uniform | heterogenous, a spurious characteristic improves. Specifically, the resonance frequency of the capacitance forming portion by the capacitance forming electrodes 24, 25 is shifted in relation to the weight of the capacitance forming electrodes 24, 25 and does not vibrate at the vibration frequency (resonance frequency) of the piezoelectric element 2. As a result, ripples and spurious can be suppressed. In addition, it is possible to suppress the resonance peak damping (attenuation) while maintaining the confinement of vibration energy (maintaining the vibration in the opposed region of the excitation electrodes 22 and 23).

  3A shows a configuration in which the thickness t2 of the capacitance forming electrodes 24 and 25 is thicker than the thickness t1 of the excitation electrodes 22 and 23, and FIG. 3B shows the thickness t2 of the capacitance forming electrodes 24 and 25. Shows a structure thinner than the thickness t1 of the excitation electrodes 22 and 23. FIG. 4 is a graph in which spurious characteristics are evaluated. The configuration of FIG. 3A (t1 <t2) is compared to the configuration in which the thickness t2 of the capacitance forming electrodes 24 and 25 and the thickness t1 of the excitation electrodes 22 and 23 are equal. ) Indicates a better spurious characteristic in which unnecessary frequency components are attenuated.

  Further, the thickness of the capacitance forming electrode 24 and the thickness of the capacitance forming electrode 25 may be different, and the ripples and spurious positions are dispersed, so that the effect of suppressing these is further enhanced.

Further, the forming material of the electrodes (excitation electrodes 22 and 23) may be different from the forming material of the capacitance forming electrodes 24 and 25. For example, when the forming material of the excitation electrodes 22 and 23 is silver, the capacitance forming electrode A configuration in which the forming material of the electrodes 24 and 25 is gold can be given. Thereby, the vibration frequency on the piezoelectric element 2 becomes non-uniform depending on the position (electrode position), so that the spurious characteristics are improved. That is, similarly to the configuration of FIG. 3, the resonance frequency of the capacitance forming portion by the capacitance forming electrodes 24, 25 is shifted in relation to the weight of the capacitance forming electrodes 24, 25, and the vibration frequency (resonance) of the piezoelectric element 2. Therefore, ripples and spurious can be suppressed. In addition, it is possible to suppress the resonance peak damping (attenuation) while maintaining the confinement of vibration energy (maintaining the vibration in the opposed region of the excitation electrodes 22 and 23).

  Further, as shown in FIG. 5, the surfaces of the capacitance forming electrodes 24 and 25 are preferably covered with an insulating film 26, and examples of the insulating film 26 include resin materials such as epoxy and silicone. Also by this, the resonance frequency of the capacitance forming portion by the capacitance forming electrodes 24 and 25 is shifted and the vibration frequency (resonance frequency) of the piezoelectric element 2 is not vibrated, so that ripples and spurious can be suppressed. Moreover, reflection of vibration energy can be reduced.

  Further, as shown in FIG. 6, the distance d1 between the electrode (excitation electrode 22) on one main surface of the piezoelectric element 2 and the capacitance forming electrode 25 is such that the electrode (excitation electrode 23) on the other main surface and the capacitance forming electrode. The distance d2 is preferably different from the distance d2, and by making the vibration of the piezoelectric element 2 left-right asymmetric, leakage and reflection of vibration energy can be dispersed in the frequency domain and the spurious frequency can be adjusted. Will improve.

  Further, as shown in FIG. 7, the gap shape between the excitation electrode 22 and the capacitance forming electrode 25 (between the excitation electrode 23 and the capacitance formation electrode 24) is curved, for example, the end face of the excitation electrode 22 The shape and the end face shape of the excitation electrode 23 are rounded so as to be convex at the center in the width direction (just like drawing a semicircle or semi-ellipse), so that the center of the piezoelectric element 2 where vibrations are concentrated Since the electrode has a shape corresponding to vibration spreading radially from the portion, leakage and reflection of vibration energy are suppressed, and resonance characteristics (resonance resistance) are improved.

  Further, as shown in FIG. 6, the area of the capacitance forming electrode 24 provided on one main surface of the piezoelectric element 2 in plan view is different from the area of the capacitance forming electrode 25 provided on the other main surface. Thus, the capacitance value C1 formed between the excitation electrode 22 and the capacitance forming electrode 24 opposed to each other with the piezoelectric body 21 interposed therebetween, and the capacitance electrode C and the excitation electrode 23 opposed to each other with the piezoelectric body 21 interposed therebetween. Since the capacitance value C2 formed with the electrode 25 can be made different, IC matching can be optimized.

  The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the scope of the present invention.

  Next, an example of a method for manufacturing a piezoelectric component according to the present embodiment will be described.

  First, a multi-piece substrate for producing the support substrate 1 is produced. For example, after the raw material powder is mixed with water and a dispersant using a ball mill, a binder, a solvent, a plasticizer, and the like are added to obtain a green sheet. The green sheet is subjected to hole processing as necessary, and then a conductive paste containing metal powder such as gold, silver, copper, aluminum, tungsten or the like is printed and laminated. This is fired at a peak temperature of, for example, 900 ° C. to 1600 ° C.

Next, for example, after the raw material powder was mixed with water and a dispersant using a ball mill, the piezoelectric body 21 constituting the piezoelectric element 2 was added with a binder, a plasticizer, and the like, and dried and sized. The raw material thus obtained is press-molded and fired to obtain a piezoelectric ceramic. An electrode is formed on the end face of the obtained piezoelectric ceramic, and the thickness direction is, for example, 0.4 kV / mm to 25 ° C. to 300 ° C.
Polarization is performed by applying a voltage of 6 kV / mm.

  The excitation electrode 22 and the excitation electrode 23, the capacitance forming electrode 24, and the capacitance forming electrode 25 formed on the upper and lower surfaces of the piezoelectric body 21 are obtained by using a vacuum evaporation method, a PVD method, a sputtering method, or the like for the obtained piezoelectric ceramic. A metal film is deposited on the upper and lower surfaces of the piezoelectric body 21 and a photoresist film having a thickness of about 1 μm to 10 μm is formed on each metal film by screen printing or the like, and then patterned by photoetching, Can be formed. The piezoelectric element 2 is produced by cutting the patterned piezoelectric ceramic into a predetermined size by dicing or the like.

  Then, using the conductive bonding material 3, a large number of piezoelectric elements 2 are mounted on the substrate and fixed. When the conductive bonding material 3 is a conductive adhesive in which metal powder is dispersed in a resin, the conductive adhesive 3 is applied onto the wiring conductors 141 and 142 using a dispenser or the like, and the piezoelectric material is piezoelectric. The element 2 may be mounted and the conductive adhesive resin may be cured by heating or ultraviolet irradiation.

  Next, frequency adjustment is performed in a state where the piezoelectric element 2 is mounted on a multi-piece substrate. In the frequency adjustment, the excitation electrodes 22 and 23 and the capacitance forming electrodes 24 and 25 formed on the surface of the piezoelectric element 2 are etched with an ion gun or the like, and matched with the IC by changing the length or thickness or changing the design value. The oscillation frequency is adjusted by connecting an oscillation frequency measurement terminal to the signal terminals 121 and 122 and the ground terminal 13 at the time of ion gun irradiation and measuring the oscillation frequency. When the oscillation frequency is reached, the ion gun is irradiated. Implement by stopping.

  Then, the opening peripheral surface of the lid 4 is joined to the peripheral portion of the upper surface of the support substrate 1 so as to cover the piezoelectric element 2. As the lid 4, a multi-piece collective cover sheet having a plurality of concave portions is used, and the multi-piece collective cover sheet is placed on the substrate so that the concave portions cover the piezoelectric elements 2. The convex portion of the collective cover sheet serving as the peripheral surface is joined to the peripheral portion of the upper surface of the support substrate 1. For example, a thermosetting insulating adhesive is applied to the convex portion of the collective lid sheet that becomes the peripheral edge of the opening of the prepared lid 4, and the lid 4 is placed on the upper surface of the support substrate 1. After that, the lid 4 or the support substrate 1 is heated to cure the insulating adhesive by raising the temperature to 100 to 150 ° C., and the lid 4 is bonded to the upper surface of the support substrate 1.

  Finally, it is cut by dicing or the like along the boundary of each piezoelectric component (piece).

  The piezoelectric component of the present invention is manufactured by the above method.

  According to the above method, a piezoelectric component with a built-in capacitor can be obtained, and a small and highly accurate piezoelectric component can be manufactured with high productivity.

1: support substrate 11: support substrate body 121, 122: signal terminal 13: ground terminals 141-143: wiring conductor 2: piezoelectric element 21: piezoelectric body 22, 23: excitation electrode 24, 25: capacitance forming electrode 26: insulation Membrane 3: Conductive bonding material 4: Lid

Claims (5)

A support substrate and a piezoelectric element having both ends fixed on the support substrate and mounted so as to vibrate. The piezoelectric element is disposed so as to have areas facing each other on one main surface and the other main surface. And the first main surface and the other main surface are insulated from the electrodes at a distance from each other and form a capacitance with the electrode disposed on the opposite main surface. A piezoelectric component comprising: a capacitor forming electrode disposed, wherein a material for forming the electrode is different from a material for forming the capacitor forming electrode .   2. The piezoelectric component according to claim 1, wherein a thickness of the electrode is different from a thickness of the capacitor forming electrode. 3. The piezoelectric component according to claim 1, wherein a surface of the capacitor forming electrode is covered with an insulating film. The distance between the electrode on the one main surface and the capacitor forming electrode is different from the distance between the electrode on the other main surface and the capacitor forming electrode. 3. The piezoelectric component according to claim 3. The area of the capacitance forming electrode provided on the one main surface in plan view is different from the area of the capacitance forming electrode provided on the other main surface. 4. The piezoelectric component according to claim 4.

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