JP2012010054A - Composite substrate and elastic wave device using thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a composite substrate from being remained warped after getting high-temperature in which a piezoelectric substrate and a support substrate are joined with a resin adhesive layer.SOLUTION: An insulating resin adhesive layer 13 which joins a rear face of a piezoelectric substrate 11 and a support substrate 12 includes conductive discharging particles which eliminate charge of the piezoelectric substrate 11. Consequently, a composite substrate 10 and an elastic wave device formed using thereof are prevented from being remained warped after getting high-temperature.

Description

  The present invention relates to a composite substrate and an acoustic wave device using the same.

Conventionally, as acoustic wave devices, surface acoustic wave devices that can function as filter elements and oscillators used in cellular phones and the like, and bulk wave devices such as thin film resonators (FBAR: Film Bulk Acoustic Resonator) are known. It has been. In such an acoustic wave device, a piezoelectric substrate having an electric conductivity of 1 × 10 ⁻¹³ [Ω ⁻¹ · cm ⁻¹ ] or higher and an insulation having an electric conductivity of 5 × 10 ⁻¹² [Ω ⁻¹ · cm ⁻¹ ] or lower It has been proposed to use a composite substrate that is bonded to a body substrate via an adhesive (see, for example, Patent Document 1). By doing so, it is described that the pyroelectric effect generated in the piezoelectric substrate is suppressed, and the amount of increase in warpage of the composite substrate can be reduced even after heat treatment at 180 ° C.

JP 2010-68484 A

  However, when a process at a temperature higher than 180 ° C. (for example, 250 ° C. or higher) such as a reflow process for mounting an acoustic wave device on a printed wiring board is performed, the pyroelectric effect is obtained in the composite substrate described in Patent Document 1. In some cases, the amount of warpage after heat treatment cannot be sufficiently reduced. Moreover, in the composite substrate described in Patent Document 1, since it is necessary to use a piezoelectric substrate and a support substrate (insulator substrate) that are in the above-described conductivity range, there is a problem that these materials are limited. . Furthermore, if the piezoelectric substrate is not a pyroelectric body, it is not necessary to suppress the pyroelectric effect, but even in this case, the warpage generated at a high temperature due to the difference in thermal expansion coefficient between the piezoelectric substrate and the support substrate remains at room temperature. May end up. If the warp remains, problems may occur in the subsequent processes. Therefore, it is desired to prevent warp after heat treatment by a method other than the method described in Patent Document 1.

  The present invention has been made to solve such a problem, and in a composite substrate in which a piezoelectric substrate and a support substrate are bonded together by a resin adhesive layer, warping remains after the temperature has once increased. The main purpose.

  The composite substrate of the present invention employs the following means in order to achieve the main object described above.

The composite substrate of the present invention is
A piezoelectric substrate capable of propagating elastic waves;
A support substrate having a smaller coefficient of thermal expansion than the piezoelectric substrate;
An adhesive layer made of an insulating resin that joins the back surface of the piezoelectric substrate and the support substrate;
With
The adhesive layer contains conductive static eliminating particles that remove electric charges of the piezoelectric substrate.
Is.

  In this composite substrate, conductive charge-removing particles that remove charges on the piezoelectric substrate are contained in a resin adhesive layer that joins the back surface of the piezoelectric substrate and the support substrate. Thereby, it is possible to prevent the warp from remaining after the composite substrate once becomes high temperature. The reason for this is considered as follows. When the composite substrate reaches a high temperature, the composite substrate is warped due to the difference in thermal expansion coefficient between the piezoelectric substrate and the support substrate, and electric charges are generated on the surface of the piezoelectric substrate due to the stress generated by the warp. Further, when the piezoelectric substrate is a pyroelectric body, the composite substrate is heated to generate charges due to the pyroelectric effect on the surface of the piezoelectric substrate. If such charges continue to exist in the piezoelectric substrate even when the temperature returns to room temperature, the piezoelectric substrate remains warped by the inverse piezoelectric effect due to the charges. In the composite substrate of the present invention, since the conductive charge-removing particles exist in the adhesive layer, it is considered that the electric charge in the piezoelectric substrate moves into the adhesive layer, so that the piezoelectric substrate is discharged and the warp is eliminated. In the composite substrate of the present invention, the charge eliminating particles may be made of carbon or metal.

  A first acoustic wave device of the present invention is formed using the composite substrate of the present invention described above, and includes an electrode capable of exciting the acoustic wave on the surface of the piezoelectric substrate. According to this elastic wave device, the same effect as that obtained with the composite substrate described above can be obtained. Examples of the acoustic wave device include a surface acoustic wave device such as a resonator, a filter, and a convolver, and a bulk wave device such as a thin film resonator.

The second acoustic wave device of the present invention is
A piezoelectric substrate capable of propagating elastic waves;
An electrode formed on a surface of the piezoelectric substrate and capable of exciting the elastic wave;
A support substrate having a smaller coefficient of thermal expansion than the piezoelectric substrate;
An adhesive layer made of an insulating resin that joins the back surface of the piezoelectric substrate and the support substrate;
A static elimination layer that is bonded to a side surface of the piezoelectric substrate and contains conductive static elimination particles that remove electric charges of the piezoelectric substrate in an insulating resin;
It is equipped with.

  In this acoustic wave device, a charge-removing layer in which electrically conductive charge-removing particles that remove charges on the piezoelectric substrate are contained in an insulating resin is provided on the side surface of the piezoelectric substrate. Thereby, since the electric charge in the piezoelectric substrate moves to the charge removal layer, the piezoelectric substrate is discharged, so that it is possible to prevent the warp from remaining after the acoustic wave device is once heated to a high temperature. In the composite substrate of the present invention, the charge eliminating particles may be made of carbon or metal.

  In the second acoustic wave device of the present invention, the charge removal layer may cover a side surface of the piezoelectric substrate. By doing so, the effect of preventing warpage of the piezoelectric substrate is enhanced.

1 is a perspective view of a composite substrate 10. FIG. 4 is an explanatory view (cross-sectional view) schematically showing a manufacturing process of the composite substrate 10. FIG. 1 is a perspective view of a 1-port SAW resonator 30 manufactured using a composite substrate 10. FIG. 2 is a cross-sectional view showing a state in which a 1-port SAW resonator 30 is mounted on a ceramic substrate 40, sealed with resin, and mounted on a printed wiring board 60. FIG. It is sectional drawing of 1 port SAW resonator 70 of another embodiment. 3 is a graph plotting the results of Comparative Example 1 in Evaluation Test 1. FIG. 6 is a graph plotting the results of Comparative Example 2 in Evaluation Test 2. FIG.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a composite substrate 10 according to an embodiment of the present invention. The composite substrate 10 is used for a surface acoustic wave device, and is formed in a circular shape with one portion being flat. This flat portion is a portion called an orientation flat (OF), and is used for detecting the wafer position and direction when various operations are performed in the manufacturing process of the surface acoustic wave device. The composite substrate 10 of this embodiment includes a piezoelectric substrate 11, a support substrate 12, and an adhesive layer 13.

  The piezoelectric substrate 11 is a piezoelectric substrate capable of propagating surface acoustic waves. Examples of the material of the piezoelectric substrate 11 include lithium tantalate, lithium niobate, lithium niobate-lithium tantalate solid solution single crystal, lithium borate, gallium nitride, and quartz. Although the magnitude | size of the piezoelectric substrate 11 is not specifically limited, For example, a diameter is 50-150 mm and thickness is 10-50 micrometers.

  The support substrate 12 is a substrate bonded to the back surface of the piezoelectric substrate 11 via the adhesive layer 13. The support substrate 12 is made of a material having a smaller thermal expansion coefficient than the piezoelectric substrate 11. Examples of the material of the support substrate 12 include silicon, sapphire, aluminum nitride, alumina, borosilicate glass, quartz glass, and spinel. Among these, silicon is the most practical material for semiconductor device fabrication, and is preferable because it is easy to composite the surface acoustic wave device fabricated using the composite substrate 10 and the semiconductor device. Although the magnitude | size of the support substrate 12 is not specifically limited, For example, a diameter is 50-150 mm and thickness is 100-500 micrometers. Further, the thermal expansion coefficient of the support substrate 12 is preferably 2 to 7 ppm / K when the thermal expansion coefficient of the piezoelectric substrate 11 is 13 to 20 ppm / K, for example. Note that the support substrate 12 is made of a material having a smaller thermal expansion coefficient than the piezoelectric substrate 11 in this way, so that the change in size of the piezoelectric substrate 11 when the temperature changes is suppressed by the support substrate 12. That is, the temperature characteristics of the composite substrate 10 are improved.

  The adhesive layer 13 adheres the back surface of the piezoelectric substrate 11 and the front surface of the support substrate 12. The adhesive layer 13 is obtained by adding conductive charge eliminating particles to an adhesive composition made of an insulating resin for bonding the piezoelectric substrate 11 and the support substrate 12. Examples of the material of the adhesive composition include an epoxy resin and an acrylic resin. Examples of the material of the charge eliminating particles include carbon or metal (for example, silver). The size of the particles is not particularly limited, and for example, the diameter is 20 to 200 nm. Further, the amount of particles in the adhesive layer 13 is not particularly limited, but is, for example, 5 to 15 wt% of the adhesive composition. Moreover, it is preferable that the thickness of the contact bonding layer 13 shall be 0.1-2 micrometers, for example. If the thickness of the adhesive layer 13 exceeds 2 μm, it is not preferable because the effect of improving the temperature characteristics of the composite substrate 10 cannot be obtained sufficiently. Further, if the thickness of the adhesive layer 13 is less than 0.1 μm, it is not preferable because sufficient adhesive strength cannot be obtained.

  A method for manufacturing such a composite substrate 10 will be described below with reference to FIG. FIG. 2 is an explanatory view (cross-sectional view) schematically showing the manufacturing process of the composite substrate 10. First, a support substrate 12 having an OF and a predetermined diameter and thickness is prepared. In addition, a piezoelectric substrate 21 in a state before polishing the piezoelectric substrate 11 is prepared (see FIG. 2A). Then, an adhesive composition containing conductive charge eliminating particles is uniformly applied to at least one of the front surface of the support substrate 12 and the back surface of the piezoelectric substrate 21. Thereafter, the two substrates are bonded together, and when the adhesive composition is a thermosetting resin, it is heated and cured, and when the adhesive composition is a photocurable resin, it is cured by irradiation with light. Thereby, the adhesive composition containing the charge eliminating particles is cured to become the adhesive layer 13, and the bonded substrate 20 (composite substrate 10 before polishing) is obtained (see FIG. 2B). Thereafter, the piezoelectric substrate 21 is polished to a predetermined thickness by a polishing machine, and the surface of the piezoelectric substrate 21 is mirror-polished, so that the piezoelectric substrate 21 before polishing becomes the piezoelectric substrate 11 and the composite substrate 10 is obtained ( (Refer FIG.2 (c)).

  The composite substrate 10 thus obtained is then formed with electrodes by using a general photolithographic technique to make the composite substrate 10 an assembly of a large number of surface acoustic wave devices. Cut out to a surface acoustic wave device. FIG. 3 shows a state where the composite substrate 10 is an assembly of 1-port SAW (Surface Acoustic Wave) resonators 30 which are surface acoustic wave devices. The 1-port SAW resonator 30 is obtained by forming IDT (Interdigital Transducer) electrodes 32 and 34 (also referred to as comb-shaped electrodes and interdigital electrodes) and a reflective electrode 36 on the surface of the piezoelectric substrate 11 by photolithography. . The obtained 1-port SAW resonator 30 is mounted on the printed wiring board 60 as follows. That is, as shown in FIG. 4, after the IDT electrodes 32 and 34 and the pads 42 and 44 of the ceramic substrate 40 are connected via the gold balls 46 and 48, the resin 50 is sealed on the ceramic substrate 40. A lead-free solder paste is interposed between the electrodes 52 and 54 provided on the back surface of the ceramic substrate 40 and the pads 62 and 64 of the printed wiring board 60, and then mounted on the printed wiring board 60 by a reflow process. Is done. FIG. 4 shows the solders 66 and 68 after the solder paste is melted and re-solidified. Here, since the 1-port SAW resonator 30 is heated to, for example, about 260 ° C. in the reflow process, warping occurs due to a difference in thermal expansion coefficient between the piezoelectric substrate 11 and the support substrate 12 during heating. And the electric charge arises on the surface of a piezoelectric substrate by the stress by this curvature. Further, when the piezoelectric substrate 11 is a pyroelectric body, the one-port SAW resonator 30 is heated to generate a charge due to the pyroelectric effect on the surface of the piezoelectric substrate 11. However, in this embodiment, the piezoelectric substrate 11 is neutralized by the movement of these charges to the neutralization particles in the adhesive layer 13. Therefore, when the 1-port SAW resonator 30 returns to room temperature after the reflow process, the piezoelectric substrate 11 does not have an inverse piezoelectric effect due to electric charges, and the warpage of the piezoelectric substrate 11 is eliminated.

  According to the composite substrate 10 of the present embodiment described in detail above, the conductive charge-removing particles that remove the electric charge of the piezoelectric substrate 11 on the adhesive layer 13 made of an insulating resin that joins the back surface of the piezoelectric substrate 11 and the support substrate 12. Is contained. Thereby, it is possible to prevent warping from remaining after the composite substrate 10 and the surface acoustic wave device formed using the composite substrate 10 are once heated to a high temperature.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, in the composite substrate 10, the insulating resin-made adhesive layer 13 contains the conductive charge-removing particles that remove the electric charges of the piezoelectric substrate 11. However, the adhesive layer 13 of the composite substrate 10 In the surface acoustic wave device formed by using the composite substrate 10, the electrically conductive charge eliminating particles for removing the charge of the piezoelectric substrate are included in the insulating resin on the side surface of the piezoelectric substrate 11. It is good also as what adheres the made static elimination layer. A cross-sectional view of the 1-port SAW resonator 70 in this case is shown in FIG. In addition, the same code | symbol shall be attached | subjected about the same component as the composite substrate 10 and 1 port SAW resonator 30 in embodiment mentioned above, and description is abbreviate | omitted. The one-port SAW resonator 70 is a composite substrate in which the back surface of the piezoelectric substrate 11 and the support substrate 12 are bonded by an adhesive layer 73. IDT electrodes 32 and 34 (not shown) and a reflective electrode 36 are provided on the surface of the piezoelectric substrate 11. Are formed. Unlike the adhesive layer 13, the adhesive layer 73 does not contain static elimination particles and is made of an insulating resin similar to the adhesive composition of the adhesive layer 13. The 1-port SAW resonator 70 includes a charge removal layer 74 that removes charges from the piezoelectric substrate 11 on the side surface of the piezoelectric substrate 11. Similar to the adhesive layer 13, the charge removal layer 74 is made of an insulating resin adhesive composition containing conductive charge removal particles. As the material of the charge eliminating particles, for example, carbon or metal can be used as in the case of the charge eliminating particles in the adhesive layer 13. For example, after the 1-port SAW resonator 70 is cut out from the composite substrate and then bonded to the side surface of the piezoelectric substrate 11 before the reflow process, the charge removal layer 74 is bonded to the composite substrate 10 and the 1-port SAW resonator 30 described above. Similarly, the effect of preventing the warp from remaining after the surface acoustic wave device 70 once becomes high temperature can be obtained. The charge removal layer 74 may be bonded to a part of the side surface of the piezoelectric substrate 14 or may cover the side surface. It is preferable to cover the side surface because the effect of preventing the warp from remaining after the temperature has once increased is increased. In FIG. 5, the charge removal layer 74 is bonded only to the side surface of the piezoelectric substrate 11, but it may be bonded to the side surface of the piezoelectric substrate 11, for example, bonded to the side surface of the adhesive layer 73 or the support substrate 12. It is good also as what is done. Furthermore, not only the charge removal layer 74 but also the adhesive layer 73 may contain charge removal particles as in the adhesive layer 13.

  In the above-described embodiment, the 1-port SAW resonator has been described as the elastic wave device manufactured using the composite substrate 10, but the same effect can be obtained even if another elastic wave device is manufactured using the composite substrate 10. Can do. Examples of other acoustic wave devices include surface acoustic wave devices such as 2-port SAW resonators, transversal SAW filters, ladder SAW filters, and convolvers, and bulk wave devices such as thin film resonators.

[Example 1]
As Example 1, the composite substrate 10 shown in FIG. 1 was produced, and the 1-port SAW resonator 30 shown in FIG. 3 was produced using the composite substrate 10.

Specifically, first, a lithium tantalate substrate (hereinafter referred to as an LT substrate) having a thickness of 250 μm and a diameter of 100 mm serving as the piezoelectric substrate 11 and a silicon substrate having a thickness of 250 μm and a diameter of 100 mm serving as the support substrate 12 were prepared. . Here, as the LT substrate, a 42 ° Y-cut X-propagation LT substrate in which the propagation direction of the surface acoustic wave is X and the cutting angle is a rotational Y-cut is used. The volume resistivity of the LT substrate was 5.0 × 10 ¹⁰ Ω · cm. Subsequently, a mixed adhesive prepared by mixing carbon particles having an average particle diameter of 50 nm as an antistatic particle in the epoxy resin adhesive in an amount of 15 wt% of the epoxy resin adhesive is prepared, and this is applied to the surface of the silicon substrate by spin coating. Applied. The specific resistance of the mixed adhesive was 2.0 × 10 ⁻⁴ Ω · cm. And it bonded so that the back surface of LT board | substrate might contact the side which apply | coated the mixed adhesive of the silicon substrate, it heated at 160 degreeC, and the bonded substrate from which the thickness of the contact bonding layer 13 after hardening was set to 1 micrometer was formed.

  Next, this bonded substrate was polished with a polishing machine until the thickness of the LT substrate became 10 μm. As a polishing machine, a machine that first thins the LT substrate and then performs mirror polishing is used. When the thickness is reduced, a bonded substrate is sandwiched between the polishing platen and the pressure plate, and a slurry containing abrasive grains is supplied between the bonded substrate and the polishing platen, and the pressure plate is used for bonding. A pressure plate that rotates while pressing the substrate against the surface plate was used. Subsequently, when performing mirror polishing, the polishing surface plate is assumed to have a pad attached to the surface and the abrasive grains are changed to a high count, and by giving rotation and revolution motion to the pressure plate, The surface of the LT substrate was mirror-polished. Specifically, first, the surface of the LT substrate of the bonded substrate was pressed against the surface of the platen, and polishing was performed with a rotation speed of 100 rpm and a polishing duration of 60 minutes. Subsequently, the polishing surface plate is assumed to have a pad attached to the surface and the abrasive grains are changed to a higher one, the pressure for pressing the bonded substrate against the surface plate surface is 0.2 MPa, the rotational speed of the rotation motion Was polished at 100 rpm, the revolution speed was 100 rpm, and the polishing time was 60 minutes. As a result, the LT substrate before polishing became the polished piezoelectric substrate 11, and the composite substrate 10 of Example 1 was completed.

  Subsequently, the IDT electrodes 32 and 34 and the reflective electrode 36 were formed on the fabricated composite substrate 10 using a general photolithography technique to form an assembly of 4000 one-port SAW resonators 30. Then, using a No. 2000 resin grindstone, dicing was performed at a rotational speed of 29000 rpm, and each one-port SAW resonator 30 was cut out. The IDT electrodes 32 and 34 are formed to have a line width of 0.55 μm and a period λ of 2.2 μm, and the reflective electrode 36 has a stripe line width of 0.55 μm and a period p of 1 / 2λ. It formed so that it might become.

[Comparative Example 1]
A composite substrate 10 is produced in the same manner as in Example 1 except that the adhesive layer 13 is formed only by an epoxy resin adhesive without mixing carbon particles, and the 1-port SAW resonator 30 is produced in the same manner as in Example 1. Was made.

[Evaluation Test 1]
Ten 1-port SAW resonators 30 of Example 1 and Comparative Example 1 were prepared as samples, placed on a hot plate set at 250 ° C., and surrounded by a SUS box. In this state, the sample was held for 3 minutes, opened, and the sample was transferred to a SUS plate having a diameter of 100 mm and a thickness of 20 mm and cooled to room temperature, and then the amount of warpage and the amount of static electricity (potential) of the piezoelectric substrate 11 were measured. The amount of warpage was measured using an optical measuring device (NV5010) manufactured by Zygo, and the amount of static electricity was measured using an electrostatic measuring device (SK-200) manufactured by Keyence. As a result, in all 10 one-port SAW resonators 30 of Example 1, the amount of warpage and the potential were zero. On the other hand, the warpage amount and potential of the 1-port SAW resonator 30 of Comparative Example 1 are as shown in FIG. In FIG. 6, nine plotted points appear because there are two 1-port SAW resonators 30 having a warp amount of 1 μm and a potential of 220V. The average value of the warpage amount of Comparative Example 1 was 1.19 μm, and the average value of the potential was 229.8V. From the result of Example 1 and the result of FIG. 6, in Example 1, the electric potential of the piezoelectric substrate 11 is removed by removing the electric charge of the piezoelectric substrate 11 once heated to the temperature by the adhesive layer 13 containing the charge eliminating particles. Becomes zero, which indicates that no warp remains.

[Example 2]
As Example 2, the 1-port SAW resonator 70 shown in FIG. The 1-port SAW resonator 70 was manufactured by manufacturing a 1-port SAW resonator in the same manner as in Comparative Example 1, and then bonding the charge removal layer 74 so as to cover the side surface of the piezoelectric substrate 11. In addition, the static elimination layer 74 used the mixed adhesive agent which mixed silver particle with an average particle diameter of 50 nm as a static elimination particle by the amount of 15 wt% of an epoxy resin adhesive in the epoxy resin adhesive. The specific resistance of the mixed adhesive was 5.0 × 10 ⁻⁵ Ω · cm. The mixed adhesive was applied with a cotton swab so as to cover the side surface of the piezoelectric substrate 11, and then cured by heating to 160 ° C. to obtain a charge removal layer 74.

[Comparative Example 2]
A 1-port SAW resonator 70 was produced in the same manner as in Example 2 except that the charge removal layer 74 was formed only with an epoxy resin adhesive without mixing carbon particles.

[Evaluation Test 2]
Ten 10-port SAW resonators 70 of Example 2 and Comparative Example 2 were prepared and heated and cooled under the same conditions as in Evaluation Test 1, and then the surface of the piezoelectric substrate 11 was tested in the same manner as in Evaluation Test 1. The amount of warpage and the amount of static electricity (potential) were measured. As a result, in all 10 one-port SAW resonators 70 of Example 2, the amount of warpage and the potential were zero. On the other hand, the warpage amount and potential of the 1-port SAW resonator 70 of Comparative Example 1 are as shown in FIG. In addition, the average value of the curvature amount of the comparative example 2 was 1.29 μm, and the average value of the potential was 229.9V. From the result of Example 2 and the result of FIG. 7, in Example 2, the electric potential of the piezoelectric substrate 11 is removed by removing the electric charge of the piezoelectric substrate 11 once heated to the temperature by the charge eliminating layer 74 containing the charge eliminating particles. Becomes zero, which indicates that no warp remains.

  DESCRIPTION OF SYMBOLS 10 Composite substrate, 11 Piezoelectric substrate, 12 Support substrate, 13 Adhesive layer, 20 Bonded substrate, 21 Piezoelectric substrate (before polishing), 30 1-port SAW resonator, 32, 34 IDT electrode, 36 Reflective electrode, 40 Ceramic substrate, 42,44 pad, 46,48 gold ball, 50 resin, 52,54 electrode, 60 printed wiring board, 62,64 pad, 66,68 solder, 70 1-port SAW resonator, 74 static elimination layer.

Claims (6)

A piezoelectric substrate capable of propagating elastic waves;
A support substrate having a smaller coefficient of thermal expansion than the piezoelectric substrate;
An adhesive layer made of an insulating resin that joins the back surface of the piezoelectric substrate and the support substrate;
With
The adhesive layer contains conductive static eliminating particles that remove electric charges of the piezoelectric substrate.
Composite board. The charge eliminating particles are made of carbon or metal.
The composite substrate according to claim 1.   3. An acoustic wave device formed using the composite substrate according to claim 1 and having an electrode capable of exciting the acoustic wave on a surface of the piezoelectric substrate. A piezoelectric substrate capable of propagating elastic waves;
An electrode formed on a surface of the piezoelectric substrate and capable of exciting the elastic wave;
A support substrate having a smaller coefficient of thermal expansion than the piezoelectric substrate;
An adhesive layer made of an insulating resin that joins the back surface of the piezoelectric substrate and the support substrate;
A static elimination layer that is bonded to a side surface of the piezoelectric substrate and contains conductive static elimination particles that remove electric charges of the piezoelectric substrate in an insulating resin;
Elastic wave device with The charge eliminating particles are made of carbon or metal.
The elastic wave device according to claim 4. The charge removal layer covers a side surface of the piezoelectric substrate;
The elastic wave device according to claim 4 or 5