JP2008182443A - Composite material vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite material vibrator capable of reducing the attenuation coefficient of a vibration in reflection layers and raising electric characteristics and vibration characteristics. <P>SOLUTION: The composite material vibrator 1 is configured that supporting members 5, 6 are coupled to a piezoelectric resonator 2 acting as a vibrating member through the reflection layers 3, 4, an acoustic impedance value Z<SB>2</SB>of the reflection layers 3, 4 is set to be smaller than the acoustic impedance values Z<SB>1</SB>, Z<SB>3</SB>of the piezoelectric resonator 2, and the supporting members 5, 6; and that the vibration from the piezoelectric resonator 2 acting as the vibration member is reflected at interfaces between the reflection layers 3, 4 and the supporting members 5, 6. The reflection layers 3, 4 are formed of the hardener of a thermoset resin composite containing a thermoset resin, a curing agent, and polystyrene particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite material vibration device in which a plurality of material portions having different acoustic impedances are combined.For example, a reflective layer having an acoustic impedance different from that of the vibration member is connected to a vibration member such as a piezoelectric element, The present invention relates to a composite material vibration device whose reflection layer is made of a thermosetting resin composition.

  2. Description of the Related Art Conventionally, as a piezoelectric resonance component constituting a piezoelectric resonator or a piezoelectric filter, a structure in which a case substrate is laminated above and below a piezoelectric vibrator element has been widely used. In this case, a space for preventing the vibration of the piezoelectric vibration portion of the piezoelectric element must be formed in the laminate. Therefore, a method for forming a recess for forming a cavity on the surface of the case substrate to be laminated on the surface of the piezoelectric element, or when laminating the case substrate on the piezoelectric substrate, the adhesive application area for forming the cavity is defined as a cavity. A method of removing the area was used. For this reason, the cavity for preventing the vibration of the piezoelectric vibrating portion has to be formed as described above, which makes it difficult to reduce the size. It was also difficult to reduce costs.

  In order to solve this problem, Patent Document 1 below can support a vibrating member with a relatively simple structure and hardly affect the vibration characteristics of the vibrating member, and can be downsized. An easy composite vibration device is disclosed. In this composite material vibration device, a holding member is connected to a vibration member serving as a vibration generation source via a reflective layer. The acoustic impedance value of the reflective layer is made smaller than the acoustic impedance value of the vibrating member, and the acoustic impedance value of the holding member is made higher than the acoustic impedance value of the reflective layer. Thereby, the vibration propagated from the vibrating member to the reflective layer is reflected at the interface between the reflective layer and the holding member. Therefore, even if it is supported using the holding member, it is difficult to affect the vibration of the vibration member. Therefore, a complicated manufacturing process such as formation of a cavity is not required.

  Patent Document 1 points out that the characteristics of the composite material vibration device can be adjusted by adjusting the Young's modulus and temperature characteristics of the reflective layer. In order to achieve such adjustment, a glass balloon or a resin balloon is dispersed in an epoxy resin or the like constituting the reflective layer.

  On the other hand, the same composite material vibration device is also disclosed in Patent Document 2 below. Here, an epoxy resin composition containing an epoxy resin and a curing agent, and at least one of the epoxy resin and the curing agent having a cycloalkane is used as a material constituting the reflective layer. Accordingly, it is said that the sound velocity in the reflective layer can be lowered and a composite material vibration device having excellent electrical characteristics can be obtained.

Patent Document 3 below shows a thermosetting resin composition containing a thermosetting resin, a curing agent, and a silicone compound as materials constituting the reflective layer in the same composite material vibration device. ing. Here, an epoxy resin or the like is shown as the thermosetting resin, and various curing agents such as amines are shown as the curing agent. In addition, it is said that the inclusion of the silicone compound can lower the sound velocity and the attenuation coefficient, thereby improving the electrical characteristics.
JP 2004-48708 A JP 2005-176323 A WO2005 / 0500838A1

  In the composite material vibration device described in Patent Documents 1 to 3, it is required to reliably reflect the vibration propagated from the vibration member to the reflection layer at the interface between the reflection layer and the holding member. In addition, in order not to impair vibration characteristics and electrical characteristics, it is strongly required that the sound velocity in the reflective layer is low and the attenuation coefficient is low.

  Patent Document 1 describes the density and Young's modulus of the reflective layer as characteristics required for the reflective layer, but does not mention any attenuation coefficient.

  Further, Patent Document 2 describes a method for reducing the sound speed and acoustic impedance of the reflective layer, but does not describe reducing the attenuation coefficient of the reflective layer.

  On the other hand, Patent Document 3 states that the attenuation coefficient and sound velocity of the reflective layer can be lowered by blending a silicone compound as described above.

  However, in the above-mentioned Patent Document 3, silicone oil, silicone rubber, or the like is also shown as a silicone compound. When silicone oil or silicone rubber is mixed with the reflective layer, the damping coefficient increases conversely, and the vibration of the composite material vibration device is increased. There was a possibility that the characteristics deteriorated.

When the silicone resin powder is mixed with an epoxy resin or the like as the silicone compound, the acoustic impedance can be lowered without significantly increasing the attenuation coefficient as compared with the attenuation coefficient of the epoxy resin. However, for example, the degree of increase in the phase maximum value θ _max , which is an electrical characteristic, is small, and the vibration characteristics of the composite material vibration device cannot be sufficiently improved.

  An object of the present invention is a composite material vibration device in which a holding member is connected to a vibration member via a reflection layer in view of the above-described state of the art, and in the reflection layer, vibrations propagated to the reflection layer. It is an object of the present invention to provide a composite material vibration device that can effectively reduce the damping coefficient and the speed of sound, thereby preventing the vibration characteristics of the composite material vibration device from being deteriorated when supported by a holding member.

According to the present invention comprises of a material having a first acoustic impedance value Z _1, a vibration member comprising a vibration generating source, a first second acoustic impedance Z ₂ is lower than the acoustic impedance Z ₁ A reflective layer made of a material and connected to the vibrating member, and made of a material having a _third acoustic impedance value Z3 larger than the _second acoustic impedance value Z2, and the vibrating member of the reflective layer is connected A composite material vibration comprising a holding member connected to the opposite side to the opposite side and configured to reflect vibration propagating from the vibrating member to the reflective layer at an interface between the reflective layer and the holding member A composite material vibration device is provided, wherein the reflective layer is made of a thermosetting resin composition including a thermosetting resin, a curing agent, and polystyrene-based particles.

  Preferably, the polystyrene-based particles are contained in the resin composition at a ratio of 10 to 56% by weight in the thermosetting resin composition. In this case, the attenuation coefficient of the reflective layer can be further reduced by blending polystyrene-based particles.

  As the thermosetting resin, preferably, an epoxy resin is used. In this case, the holding member can be firmly bonded to the vibration member by a curing system composed of an epoxy resin and a curing agent. A composite material vibration device excellent in mechanical strength can be provided.

  In the composite material vibration device according to the present invention, the reflective layer is composed of a thermosetting resin composition containing a thermosetting resin, a curing agent, and polystyrene particles. The damping coefficient of vibration at can be made sufficiently small. Therefore, the vibration characteristics of the composite material vibration device can be improved, and when the vibration member is an electromechanical transducer such as a piezoelectric element, the electric characteristics can be improved.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is an exploded perspective view of a composite material vibration device according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing an appearance.

  In the composite material vibration device 1 of the present embodiment, a piezoelectric resonator 2 is used as a vibration member. The piezoelectric resonator 2 is configured using a ceramic plate made of a lead zirconate titanate-based piezoelectric ceramic having a rectangular plate shape. The ceramic plate is polarized in the thickness direction. An excitation electrode 11 is formed at the center of the upper surface of the ceramic plate. Although not shown in FIG. 1, an excitation electrode is also formed at the center of the lower surface. The excitation electrode 11 is electrically connected to an extraction electrode 11a formed so as to reach one end face of the ceramic plate. Also on the lower surface of the ceramic plate, the excitation electrode is connected to the extraction electrode reaching the other end surface of the ceramic plate.

By applying an AC voltage between the excitation electrode 11 and the excitation electrode on the lower surface, the piezoelectric resonator 2 is excited in the thickness longitudinal vibration mode. Note that the acoustic impedance _{Z 1} of the ceramic plate is ^{18.8 × 10 6 N · s ·} m -3.

  First and second reflective layers 3 and 4 are laminated on the upper and lower surfaces of the piezoelectric resonator 2. First and second holding members 5 and 6 are laminated on the outer surfaces of the reflective layers 3 and 4, that is, on the surface opposite to the surface to which the piezoelectric resonator 2 is connected. The material constituting the reflective layers 3 and 4 is an adhesive material that is liquid before use and solidifies by drying or chemical reaction.

  More specifically, in this embodiment, the reflection layers 3 and 4 are made of a thermosetting resin composition containing a thermosetting resin, a curing agent, and polystyrene-based particles. When the thermosetting resin composition is cured, that is, the holding members 5 and 6 are firmly bonded to the piezoelectric resonator 2 using the adhesive force of the reflective layers 3 and 4.

Incidentally, in the present embodiment, a cured product of the thermosetting resin composition has a second acoustic impedance Z _2. The second acoustic impedance value Z ₂ is smaller than the first acoustic impedance value Z ₁ = 18.8 × 10 ⁶ N · s · m ⁻³ .

  Details of the thermosetting resin composition will be described later.

In the present embodiment, the holding members 5 and 6 are made of ceramics, and the acoustic impedance value thereof, that is, the third acoustic impedance value Z ₃ is 18.8 × 10 ⁶ N · s · m ⁻³ . , higher than the second acoustic impedance _{Z 2.}

  The holding members 5 and 6 are made of a ceramic plate having a rectangular plate shape. A pair of capacitive electrodes 12 and 13 are formed on the upper surface of the lower holding member 6. A capacitive electrode (not shown) is formed at the center of the lower surface of the holding member 6 so as to face the capacitive electrodes 12 and 13 via the holding member 6. A capacitor is formed in the holding member 6 by the capacitive electrodes 12 and 13 and the capacitive electrode on the lower surface.

  The external electrode 14 shown in FIG. 2 is formed on one end face of the laminate formed by laminating the members shown in FIG. An external electrode 15 is also formed on the other end surface of the laminate. The external electrodes 14 and 15 are electrically connected to the excitation electrode 11 of the piezoelectric resonator 2 and the excitation electrode on the lower surface, respectively.

  The external electrodes 14 and 15 are electrically connected to the capacitive electrodes 12 and 13, respectively.

  Therefore, by electrically connecting the external electrodes 14 and 15 and the capacitance electrode formed on the lower surface of the holding member 6 to the outside, the composite material vibration device 1 operates as a three-terminal type capacitor with built-in capacitance.

  In the composite material vibration device 1 of the present embodiment, the first and second reflection layers 3 and 4 are connected to the upper and lower surfaces of the piezoelectric resonator 2 as a vibration member. Holding members 5 and 6 are connected to the surface opposite to the side connected to the child 2. Accordingly, a cavity for preventing the vibration of the piezoelectric resonator 2 is not formed. Therefore, since it is not necessary to form a cavity, it is possible to achieve downsizing and cost reduction.

The reason why the cavity can be omitted as described above is that the acoustic impedance value Z ₂ of the reflective layers 3 and 4 is the acoustic impedance value Z ₁ and Z _{3 of the} material constituting the piezoelectric resonator 2 and the holding members 5 and 6. It is because it is smaller than. Providing such a reflective layer having an acoustic impedance value Z ₂ lower than the first and third acoustic impedance values Z ₁ and Z ₃ allows propagation from the piezoelectric resonator side at the interface between the reflective layer and the holding member. The ability to reflect vibrations is also disclosed in Patent Documents 1 to 3 and the like described above, and has been known since before the filing of the present application.

  The feature of this embodiment is that the reflective layers 3 and 4 are made of the thermosetting resin composition containing polystyrene particles. That is, by blending polystyrene-based particles, the damping coefficient of vibration by the reflective layers 3 and 4 can be effectively lowered, and thereby the electrical characteristics of the composite material vibration device can be enhanced.

  The thermosetting resin used in the thermosetting resin composition is not particularly limited. For example, epoxy resin, urethane resin, phenol resin, vinyl ester resin, urea resin, melamine resin, unsaturated polyester resin, polyimide resin. And so on. Preferably, the cured product is excellent in mechanical strength, and the holding member can be firmly bonded to the piezoelectric resonator. Therefore, it is desirable to use an epoxy resin as the thermosetting resin.

  The epoxy resin is not particularly limited. For example, bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, ortho cresol novolac type epoxy resin, alicyclic epoxy resin, biphenyl type epoxy resin, aralkyl type epoxy. Resin, halogenated epoxy resin, triphenolmethane type epoxy resin, naphthalene novolak type epoxy resin, aromatic amine type epoxy resin, phenol polyfunctional epoxy resin, dicyclopentadiene phenol type epoxy resin, tetraglycidyl-1,3- Examples include bisaminomethylcyclohexane.

  Moreover, only 1 type may be used for the said epoxy resin, and 2 or more types may be used together.

  As the curing agent, an appropriate compound that cures the thermosetting resin is used. When the thermosetting resin is an epoxy resin, for example, amines, aliphatic polyamines, modified aliphatic polyamines, acid anhydrides, phenols, imidazoles, epoxy adduct imidazoles, amine adducts, diaminodiphenyl sulfone, etc. Can be mentioned. More specifically, an isocyanuric acid adduct of 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine can be used as the curing agent. Furthermore, the said hardening | curing agent may be used by 1 type, and may mix and use 2 or more types.

  A feature of the present embodiment is that polystyrene particles are blended in addition to the thermosetting resin and the curing agent. By blending the polystyrene-based particles, the attenuation coefficient in the reflective layers 3 and 4 can be lowered.

  As the polystyrene-based resin constituting the polystyrene-based particles, a copolymer of styrene and another monomer can be used as appropriate in addition to polystyrene, which is a homopolymer of styrene. Examples of such a copolymer include polystyrene-divinylbenzene copolymer and styrene-acrylonitrile copolymer.

  The polystyrene particles are preferably spherical. Of course, the particles are not limited to spherical particles, but may be particles having an aspect ratio other than 1.

  The blending ratio of the polystyrene-based particles is preferably in the range of 10 to 56% by weight in the thermosetting resin composition. If the amount is less than 10% by weight, the attenuation coefficient may not be sufficiently lowered. If the amount exceeds 56% by weight, the viscosity of the thermosetting resin composition becomes high, and the workability when forming the reflective layer is deteriorated. There is a fear.

  In addition, 10-56 weight% in a thermosetting resin composition means the ratio of the polystyrene-type particle when the sum total of the said thermosetting resin, a hardening | curing agent, and a polystyrene-type particle is 100 weight%. And Therefore, when a solvent and other additives are blended, the blending ratio of the polystyrene-based particles may be 10 to 56% by weight with respect to 100% by weight of the thermosetting resin composition excluding these. .

  Next, a specific experimental example will be described to clarify the effect of blending the polystyrene-based particles.

(Experimental example 1)
Tetraglycidyl-1,3-bisaminomethylcyclohexane (epoxy equivalent 100 g / eq) as an epoxy resin and 2,4-diamino-6- [2′methylimidazolyl- (1 ′)]-ethyl-s as a curing agent -The isocyanuric acid adduct of triazine and spherical styrene-divinylbenzene copolymer having an average particle size of 3 µm as polystyrene-based particles were weighed so as to have the blending ratio shown in Table 1 below. And each thermosetting resin composition of Examples 1-4 was prepared.

  Next, each thermosetting resin composition is poured into a molded body made of a fluorinated ethylene resin, vacuum degassed, and left in an oven at a temperature of 180 ° C. for 1 hour, each having a thickness of 25 mm × 35 mm × 2 mm. A cured resin sample was obtained. About each resin cured material sample, the viscoelasticity was measured using an ultrasonic viscoelasticity measuring apparatus (manufactured by RITEC, product number: RAM-10000). Wave) was calculated.

Damping coefficient α = {ln [(A ₀ ² −A ² ) / (A ₀ B)]} / (17.32 × L × 10 ³ ) (1)
In Equation (1), A ₀ represents the amplitude (m) of the reflected wave at the bottom surface of the buffer material of the ultrasonic viscoelasticity measuring device, and A represents the amplitude of the reflected wave at the boundary surface between the buffer material and the cured resin sample ( m), B represents the amplitude (m) of the reflected wave at the bottom of the cured resin, and L represents the thickness (m) of the cured resin sample.

  Further, using the ultrasonic viscoelasticity measuring apparatus, the sound velocity C of the longitudinal wave at 5 MHz of each cured resin sample was determined by the following equation (2).

Speed of sound C (m / sec) = L / t Equation (2)
In formula (2), L is the thickness (m) of the cured resin sample, and t is the propagation time (seconds).

  Moreover, the density of each said resin cured material sample was calculated | required from the weight and volume of the resin cured material sample, and the cured material density was set to (rho).

Furthermore, the sound velocity C obtained in the above sound speed evaluation and density measurements, using the cured product density [rho, was determined acoustic impedance Z ₂ of the resin cured product constituting the reflective layer by the following equation (3).

Acoustic impedance Z ₂ = ρ × C (3)

(Experimental example 2)
The composite material vibration device 1 shown in FIGS. 1 and 2 was actually manufactured. The piezoelectric resonator 2 is made of a lead zirconate titanate ceramic having an acoustic impedance value Z ₁ = 18.8 × 10 ⁶ N · s · m ⁻³ as described above, and the holding members 5 and 6 also have an acoustic impedance value. Z ₃ is made of a ceramic of 18.8 × 10 ⁶ N · s · m ⁻³ . The piezoelectric resonator 2 was coated with the resin composition prepared in each of Examples 1 to 4, and the holding members 5 and 6 were bonded together. The resin composition was cured. When the resin composition is applied, the thickness of the cured resin, i.e., the reflective layers 3 and 4, is set to λ / 4 with respect to the wavelength λ corresponding to the resonance frequency of the piezoelectric resonator 2. Adjusted.

  Next, the nichrome film, the monel film, and the silver film shown in FIGS. 1 and 2 are sequentially formed, and then nickel tin plating is performed thereon to form the external electrodes 14 and 15. Obtained.

For the composite material vibration devices of Examples 1 to 4 obtained as described above, an impedance analyzer (manufactured by Hewlett-Packard Co., product number: HP4194A) was used to measure the maximum phase value θ _max as electrical characteristics. The larger the maximum phase value θ _max , the better the electrical characteristics of the product. The results are shown in Table 1 below.

Here, the “phase” is a phase when the electrical impedance of the composite material vibration device 1 is displayed in a complex manner. As the maximum value θ _{max of the} phase is closer to 90 degrees, oscillation is more stable.

  The electrical equivalent circuit of the composite material vibration device 1 is as shown in FIG. When the impedance of the equivalent circuit is Z, the impedance Z is expressed by the following formula (4). In the following (4), R represents a resistance component of impedance Z, and X represents a reactance component.

Z = R + jX Formula (4)
At this time, the phase θ is expressed by the following equation (5).

θ = tan ⁻¹ (X / R) (5)
(Comparative Example 1)
For comparison, a composite material vibration device was prepared using the resin composition prepared in the same manner as in Example 1 except that the polystyrene-based particles were not included. evaluated. The results are also shown in Table 1 below.

As is clear from Table 1, since Comparative Example 1 does not contain polystyrene-based particles, the reflection layer has a high attenuation coefficient of 1.17, and the maximum value θ _max of the phase in the obtained composite vibration device is It stayed at 81.5 degrees.

On the other hand, in Examples 1 to 4, since the polystyrene-based particles are contained in the thermosetting resin composition constituting the reflective layers 3 and 4, the attenuation coefficient is lowered to 1.07 or less. It can be seen that the maximum value θ _{max of the} phase exhibiting the characteristic is increased to 82.0 degrees or more.

  In the above-described embodiment, the composite material vibration device in which the vibration generation source is a piezoelectric resonator has been described. However, the vibration member of the composite material vibration device according to the present invention is not limited to a piezoelectric resonator, but a piezoelectric filter. In addition, the vibrating member is not limited to the one using the piezoelectric effect, and a vibrating member serving as a generation source for generating various vibrations can be used. In any case, since the reflection layer is made of a resin composition containing polystyrene-based particles, the damping coefficient of vibration propagated from the vibration member to the reflection layer can be lowered, thereby reducing the influence of the support by the holding member. The vibration characteristics and electrical characteristics of the composite material vibration device can be enhanced by reducing the size.

As for the holding member is not limited to using the ceramic, as long as it has a second acoustic impedance value Z ₂ acoustic impedance Z ₃ large third than, other ceramics or other non-ceramic, It can be made of a material.

The disassembled perspective view of the composite material vibration apparatus which concerns on one Example of this invention. The perspective view which shows the external appearance of the composite material vibration apparatus which concerns on one Example of this invention. The figure which shows the equivalent circuit of the composite material vibration apparatus of one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Composite material vibration apparatus 2 ... Piezoelectric resonator 3, 4 ... Reflective layer 5, 6 ... Holding member 11 ... Excitation electrode 12, 13 ... Capacitance electrode 14, 15 ... External electrode

Claims (3)

A vibration member made of a material having a _first acoustic impedance value Z ₁ and serving as a vibration source;
A reflective layer made of a material having a _second acoustic impedance value Z ₂ lower than the first acoustic impedance value Z ₁ and connected to the vibrating member;
Made of a material having an acoustic impedance value Z ₃ large third than the second acoustic impedance value Z _2, to the side where the vibrating member of the reflective layer is connected to the holding member connected to the opposite side With
A composite material vibration device configured to reflect vibration propagating from the vibration member to the reflection layer at the interface between the reflection layer and the holding member,
The composite material vibration device, wherein the reflective layer is made of a thermosetting resin composition including a thermosetting resin, a curing agent, and polystyrene-based particles.   The composite material vibration device according to claim 1, wherein the polystyrene-based particles are contained in the thermosetting resin composition in a proportion of 10 to 56% by weight in the thermosetting resin composition.   The composite material vibration device according to claim 1, wherein the thermosetting resin is an epoxy resin.

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