JP2005354430A - Surface acoustic wave transducer and surface acoustic wave device employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a SAW transducer used for an ETC on-vehicle apparatus or the like and a SAW device employing the same whereby a broadband filter characteristic with a reduced in-band deviation can be obtained. <P>SOLUTION: The SAW transducer with a plurality of concatenated basic ranges each having a width equivalent to a wavelength λ of a stimulated SAW is located on a 128±5° rotation Y-cut X propagation lithium niobate substrate. Each of the basic ranges includes a positive electrode finger 1 and a negative electrode finger 2, and the positive electrode finger 1 and the negative electrode finger 2 are arranged in a way that the center distance is almost λ/2. When Al or an alloy whose major component is Al is used for the electrode material, a relation of the electrode film thickness H/λ and the electrode width W/λ normalized by the wavelength λ is 0.38≤W/λ<0.42 in the case of H/λ <0.01, is 0.22≤W/λ<0.42 in the case of 0.01≤H/λ≤0.03, and is 0.08<W/λ≤0.25 in the case of 0.03<H/λ. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface acoustic wave transducer in which lithium niobate is used for a piezoelectric substrate and one positive electrode finger and one negative electrode finger are arranged in a basic section corresponding to one wavelength of a surface acoustic wave.

  In recent years, surface acoustic wave (hereinafter referred to as SAW) devices have been widely used in the field of mobile communication, and are particularly frequently used in mobile phones because of their excellent characteristics such as high performance, small size, and mass productivity. In addition, the SAW filter for IF used in the low frequency band among the SAW devices is used not only for mobile phones but also for ETC on-board devices and TV components, and has a wide band and symmetrical characteristics with respect to the center frequency, that is, within the band. A characteristic with small deviation (ripple) is required. A transversal SAW filter is most suitable as a SAW filter satisfying such specifications.

  FIG. 8 is a plan view showing a conventional transversal SAW filter, in which an input SAW converter 32 and an output SAW converter 33 are arranged on the main surface of the piezoelectric substrate 31 along the SAW propagation direction. And a shield electrode 34 for shielding the direct wave between the input and output terminals is disposed between the SAW converters 32 and 33. Each of the SAW converters 32 and 33 is composed of a pair of comb electrodes having a plurality of electrode fingers which are interleaved with each other. One of the comb electrodes of the SAW converter 32 is connected to the input terminal IN and the other The comb electrode is grounded. Then, one of the comb electrodes of the SAW converter 33 is connected to the output terminal OUT and the other comb electrode is grounded. Further, a sound absorbing material 35 is applied to both ends of the piezoelectric substrate 31 in the long side direction (SAW propagation direction) in order to suppress the reflected wave from the substrate end face.

  The SAW converters 32 and 33 shown in FIG. 8 have a single (regular) electrode structure in which electrode fingers are arranged in order of positive, negative, and positive, and one positive electrode finger and one negative electrode finger are arranged for each SAW wavelength 1λ. It is. In the SAW converter, there are various electrode structures other than the single electrode. As an example, FIG. 9A shows an electrode structure called a split (double) electrode. In the split electrode structure, electrode fingers having a width of approximately λ / 8 are arranged in order of positive, positive, negative, and negative so that the distance between the centers is λ / 4, and the positive electrode fingers are arranged per 1λ wavelength of SAW. And two negative electrode fingers are arranged. As another example, FIG. 9B shows a structure called DART (Distributed Acoustic Reflection Transducer) which is a typical example of a single phase unidirectional electrode (SPUDT) in which the direction of SAW excitation is directed. Is shown. This DART structure is described in T. Kodama, H. Kawabata, Y. Yasuhara and H. Sato: Design of Low-loss SAW Filters Employing Distributed Acoustic Reflection Transducers, IEEE Ultrason. Symp. Proc., Pp. 59-64 (1986). The electrode finger pair consisting of three electrode fingers is arranged between 1λ, the width of each electrode finger is W1 = 3λ / 8, W2 = W3 = λ / 8, and the left end The center position of each electrode finger is d1 = λ / 4, d2 = 5λ / 8, and d3 = 7λ / 8, where is the origin 0.

Further, when a SAW filter is formed using the above-described SAW converter, as shown in FIG. 10A, matching is performed on the input / output side of the SAW filter in order to match the power source side impedance _RS and the load impedance _RL. Circuits MC1 and MC2 are attached. The matching circuits MC1 and MC2 often use an inexpensive inductor (L) having a low Q value. However, there is a risk that the insertion loss and flatness of the pass characteristic may deteriorate due to the influence of L having a large manufacturing error. . In such a case, it is necessary to reduce the sensitivity of the SAW filter and the matching circuits MC1 and MC2 to L. FIG. 10B shows an equivalent circuit diagram of the comb electrode of the SAW filter. In order to reduce the sensitivity between the SAW filter and L of the matching circuits MC1 and MC2, the electrical Q ( = (Ba + ωCt) / Ga) is lowered to increase the effective excitation efficiency. This electrical Q is described in detail in B. Abbot and CSHartmann: An Efficient Evaluation of the Electrostatic Fields in IDTs with Periodic Electrode Sequences, IEEE Ultrason. Symp. Proc., Pp157-160 (1993). If a SAW converter with a low electrical Q can be realized, even if a matching circuit is formed with an inexpensive inductor having a low Q value, the filter characteristics can be reduced and good flatness can be realized.

  Here, electrical Q was compared for each electrode structure of the single electrode, split electrode, and DART described above. FIG. 11 shows a comparison of the electrical Q of the split electrode and DART when the electrical Q of the single electrode is 1. As shown in the figure, the split Q has a larger electrical Q of 1.305 times and the DART has a 2.144 times that of a single electrode. From the above, it can be said that the single electrode has the lowest electrical Q and excellent effective excitation efficiency.

By the way, SAW filters used as ETC in-vehicle devices and TV parts are required to have a wide band characteristic. As specific specifications, for ETC on-board equipment, a center frequency of 40 (MHz) and a pass bandwidth of 4 (MHz) or more are required, and a specific bandwidth that is a ratio of the center frequency to the pass bandwidth is 10% or more. Is required. For TV components, a center frequency of 57 (MHz) and a pass bandwidth of 5 (MHz) or more are required, and a specific bandwidth of 8.8% or more is required. Such in order to satisfy a wide band specifications, it is necessary to use a high piezoelectric substrate having an electromechanical coupling coefficient k ^2, such as lithium niobate (LN).

  Further, there is an electrode film thickness as a problem in manufacturing a filter used in a low frequency band. There is a limit to the electrode film thickness that can be produced during mass production, and it is generally difficult to accurately form an electrode having a film thickness exceeding 1 μm. In addition, as the film thickness increases, the time required for the film forming process and the etching process becomes longer, and the working efficiency is remarkably deteriorated. Therefore, it is necessary to select an electrode structure that provides good characteristics even when the electrode film thickness is reduced.

  For example, when the electrode structure is DART, the electrode film thickness H / λ normalized by the SAW wavelength λ needs to be 0.03 or more. Therefore, an electrode film thickness of 3 μm or more is required for the ETC on-vehicle device, and the manufacturing efficiency is remarkably deteriorated. Further, when the electrode film thickness H / λ is set to 0.03 or less, sufficient directivity cannot be obtained, and there is a disadvantage that the filter characteristic is unimodal because the loss is low only in the central portion of the passband.

According to Kenya Hashimoto, Introduction to surface acoustic wave device simulation, Realize Co., Ltd., pp.85., The relationship between the electromechanical coupling coefficient and the realizable bandwidth is expressed by the following equation.
BW ₃ / fo = (2η ² k ₂ /2.257) ^1/2
Here, BW ₃ is a maximum passband width that can be realized at a position 3 dB down from the insertion loss, fo is a center frequency, k ₂ is an electromechanical coupling coefficient, and η is an element that represents an effective excitation efficiency considering the electrode shape. It is a coefficient. As shown in FIG. 11, DART has an effective excitation efficiency of electrical Q that is less than half that of a single electrode, and η in the above equation is small, so that the realizable bandwidth is narrower than that of a single electrode. It is disadvantageous for widening the bandwidth. Although it is possible to increase the bandwidth at the expense of insertion loss, it is difficult to improve the performance of the filter characteristics anyway. In addition, the split electrode is inferior to the single electrode in terms of wide band because the excitation efficiency is lower than that of the single electrode.

From the above, it can be said that the single electrode is the most suitable structure for widening the band, but when the SAW reflection occurs in the conventional single electrode, either the low band or the high band of the pass band is determined depending on the reflection direction. As a result, the in-band deviation becomes large and the passband becomes asymmetric with respect to the center frequency. FIG. 12 shows a transversal SAW filter in which a SAW converter is formed with a single electrode shown in FIG. 8, with a center frequency of 40 (MHz) for ETC on-board equipment, an electrode film thickness H / λ = 0.01, and an electrode width. The filter characteristics when W / λ = 0.25 are shown, but it can be seen that the in-band deviation is large and the characteristics are asymmetric with respect to the center frequency.
T. Kodama, H. Kawabata, Y. Yasuhara and H. Sato: Design of Low-loss SAW Filters Employing Distributed Acoustic Reflection Transducers, IEEE Ultrason.Symp.Proc., Pp. 59-64 (1986). B. Abbot and CSHartmann: An Efficient Evaluation of the Electrostatic Fields in IDTs with Periodic Electrode Sequences, IEEE Ultrason.Symp.Proc., Pp157-160 (1993). Written by Kenya Hashimoto, Introduction to surface acoustic wave device simulation, Realize Inc., pp.85.

  In SAW devices that require a wide band and small in-band deviation characteristics such as for ETC on-board devices, it is advantageous to increase the bandwidth by forming a SAW converter with a single electrode, but the in-band deviation increases due to SAW reflection. As a result, there is a problem that the characteristics become asymmetric with respect to the center frequency.

  In order to achieve the above object, the SAW converter according to the present invention and the SAW device using the SAW converter according to claim 1 are arranged on a 128 ± 5 ° rotated Y-cut X-propagating lithium niobate substrate to provide an elastic surface. A surface acoustic wave converter for forming a wave element, the surface acoustic wave converter having a configuration in which a plurality of basic sections having a width corresponding to the wavelength λ of a surface acoustic wave to be excited are connected. The basic section has one positive electrode finger and one negative electrode finger, and the positive electrode finger and the negative electrode finger are arranged so that a center-to-center distance is approximately λ / 2. When the electrode material of the surface acoustic wave converter is Al or an alloy containing Al as a main component, the relationship between the electrode film thickness H / λ normalized by the wavelength λ and the electrode width W / λ is expressed as H / λ < When 0.01, 0.38 ≦ W / λ <0.42, and 0.01 ≦ H / λ ≦ 0.0 It is characterized in that a 0.22 ≦ W / lambda and <0.42, 0.03 <0.08 <W / λ ≦ 0.25 when the H / lambda when the.

  According to the second aspect of the present invention, when the electrode material of the surface acoustic wave converter is made of Mg or an alloy mainly composed of Mg, the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ. When H / λ <0.02, 0.28 ≦ W / λ <0.42, and when 0.02 ≦ H / λ ≦ 0.03, 0.20 ≦ W / λ ≦ When 0.30 and 0.03 <H / λ, 0.08 <W / λ ≦ 0.22 is set.

  According to a third aspect of the present invention, when the electrode material of the surface acoustic wave converter is made of Cu or an alloy containing Cu as a main component, the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ. When H / λ <0.005, 0.25 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.30. It is characterized by doing.

  According to a fourth aspect of the present invention, when the electrode material of the surface acoustic wave converter is made of Ag or an alloy containing Ag as a main component, the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ. When H / λ <0.005, 0.30 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.35. It is characterized by doing.

  According to the fifth aspect of the present invention, when the electrode material of the surface acoustic wave converter is made of Au or an alloy containing Au as a main component, the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ. When H / λ <0.005, 0.18 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.25. It is characterized by doing.

  The invention described in claim 6 is a surface acoustic wave device in which at least one surface acoustic wave transducer is arranged.

  According to the first and sixth aspects of the present invention, 128 ± 5 ° rotated Y-cut X-propagating lithium niobate is used for the piezoelectric substrate, the electrode structure is a single electrode, and the electrode material is Al or an alloy mainly composed of Al. In the SAW converter and the SAW device using the SAW converter, the electrode width is set such that the amount of reflection is zero according to the electrode film thickness, so that it is possible to realize a filter characteristic with a wide band and reduced in-band deviation.

  According to the inventions of claims 2 and 6, since the electrode material is Mg or an alloy containing Mg as a main component, the amount of frequency fluctuation when the film thickness fluctuates as compared with Al is small, so that the production yield Can be improved.

  According to invention of Claim 3 thru | or 6, since the said electrode material was made into Cu, Ag, Au, or an alloy which has those as a main component, it is an electrode with a thin electrode film thickness and a reflection zero compared with Al. Since the width can be set, the manufacturing efficiency can be improved.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings. FIG. 1 is an enlarged view of a part of a SAW converter according to the present invention. The SAW converter has a configuration in which a plurality of basic sections having a width corresponding to the wavelength λ of the SAW excited on the piezoelectric substrate are connected, and the positive electrode finger 1 and the negative electrode finger in one basic section. 2 is a single electrode in which the center-to-center distance is λ / 2. In this embodiment, 128 ± 5 ° rotated Y-cut X-propagating lithium niobate (hereinafter referred to as 128 ± 5 ° LN) is used for the piezoelectric substrate, and the electrode is made of Al or an alloy containing Al as a main component. .

  As described above, the conventional single electrode has a problem that the in-band deviation becomes large due to the influence of SAW reflection, and the passband becomes asymmetric with respect to the center frequency. In the present invention, in view of this problem, the in-band deviation is reduced by setting the electrode width so that the SAW reflection becomes zero, and the passband is flattened. In this example, K. Hashimoto and M. Yamaguchi: Free So-ftware Products for Simulation and Design of Surface Acoustic Wave and Surface Transverse Wave Devices, Freq. Contr. Symp. Proc., Pp. 300-307 (1996) The FEM analysis tool “Multi” shown in FIG. The Kovacs constant is used as the material constant of 128 ± 5 ° LN, and the constant incorporated in the software is used as it is as the material constant of Al.

  FIG. 2 shows the relationship between the electrode width and the reflection amount when the electrode film thickness H / λ is changed in the single electrode of FIG. The horizontal axis represents the electrode width W / λ normalized by the wavelength λ, and the vertical axis represents the coefficient | κ12 ′ obtained by multiplying the absolute value | κ12 | of the mutual coupling coefficient in the mode coupling theory by the wave number k0 (= 2π / λ). | Represents the SAW reflection amount in the basic section. From the same figure, when H / λ = 0.01, W / λ = 0.38, when H / λ = 0.02, W / λ = 0.28, H / λ = 0. When 03 is set, the reflection amount becomes almost zero near W / λ = 0.25. Thus, it was confirmed that there is an electrode width where the reflection amount becomes zero in the single electrode, and that the electrode width where the reflection amount becomes zero decreases as the electrode film thickness increases.

  FIG. 3 shows a transversal SAW filter using a SAW converter when the electrode film thickness is H / λ = 0.01 and the electrode width is W / λ = 0.38 where the reflection amount is almost zero. The pass characteristics are shown. The center frequency is 40 MHz for ETC on-vehicle equipment. From the figure, a characteristic having a wide bandwidth of 5 MHz or more, that is, 10% or more is obtained at a position 3 dB down from the insertion loss, and in comparison with the pass characteristic of the conventional single electrode shown in FIG. It can be seen that the deviation is greatly reduced, and a symmetrical characteristic with respect to the center frequency is obtained.

  Thus, in the present invention, when 128 ± 5 ° LN is used for the piezoelectric substrate and the electrode structure of the SAW converter is a single electrode, the relationship between the electrode film thickness and the electrode width at which SAW reflection is zero is obtained. The headline and in-band deviation could be greatly reduced.

  By the way, in the single electrode, if the electrode width is W / λ <0.08 or 0.42 <W / λ, the manufacturing efficiency is deteriorated. Therefore, within the range of 0.08 <W / λ <0.42. Therefore, it is necessary to set the electrode width at which the reflection amount becomes zero. Therefore, when H / λ <0.01, 0.38 ≦ W / λ <0.42, and when 0.01 ≦ H / λ ≦ 0.03, 0.22 ≦ W / λ <0.42. When 0.03 <H / λ, it is preferably set within the range of 0.08 <W / λ ≦ 0.25.

  So far, only the case where the electrode material is Al or an alloy containing Al as a main component has been described, but the present invention can be applied to other electrode materials. Hereinafter, a case where an electrode material other than Al is used will be described.

  FIG. 4 shows the relationship between the electrode width W / λ and the reflection amount | κ12 ′ | when the electrode film thickness H / λ is changed when the electrode material of the single electrode is Mg. From the figure, it can be seen that even when the electrode material is Mg, there is an electrode width where the amount of reflection is zero, as in Al, and when the electrode film thickness is increased, the electrode width where the amount of reflection is zero is reduced. Specifically, the electrode width at which the reflection amount is zero is H / λ = 0.02 and W / λ = 0.28, H / λ = 0.03 and W / λ = 0.22, When /λ<0.02, 0.28 ≦ W / λ <0.42, and when 0.02 ≦ H / λ ≦ 0.03, 0.20 ≦ W / λ ≦ 0.30 and 0 When 0.03 <H / λ, 0.08 <W / λ ≦ 0.22 is preferable. Further, since Mg has a small frequency fluctuation amount when the film thickness fluctuates as compared with Al, the manufacturing yield can be improved.

  FIG. 5 shows the relationship between the electrode width W / λ and the reflection amount | κ12 ′ | when the electrode film thickness H / λ is changed when the electrode material of the single electrode is Cu. Compared to Al, the reflection amount is generally small, and the value of the electrode width at which the reflection amount becomes zero under the same film thickness condition is small. Specifically, the electrode width at which the reflection amount becomes zero is H / λ = 0.005 and W / λ = 0.25, H / λ = 0.01 and W / λ = 0.12. When /λ<0.005, it is preferable that 0.25 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.30.

  FIG. 6 shows the relationship between the electrode width W / λ and the reflection amount | κ12 ′ | when the electrode film thickness H / λ is changed when the electrode material of the single electrode is Ag. Like Cu, the reflection amount is generally smaller than that of Al, and the electrode width value at which the reflection amount becomes zero under the same film thickness condition is small. Specifically, the electrode width at which the reflection amount becomes zero is H / λ = 0.005 and W / λ = 0.30, H / λ = 0.01 and W / λ = 0.12. When /λ<0.005, it is preferable to satisfy 0.30 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.35.

  FIG. 7 shows the relationship between the electrode width W / λ and the reflection amount | κ12 ′ | when the electrode film thickness H / λ is changed when the electrode material of the single electrode is Au. The total reflection amount is small compared to Al, such as Cu and Ag, and the value of the electrode width at which the reflection amount is zero under the same film thickness condition is small. Specifically, the electrode width at which the reflection amount is zero is H / λ = 0.005 and W / λ = 0.18, H / λ = 0.01 and W / λ = 0.07, When /λ<0.005, 0.18 ≦ W / λ <0.42, and when 0.005 ≦ H / λ, 0.08 <W / λ ≦ 0.25 is preferable.

  Thus, it was confirmed that there is an electrode width where reflection is zero even with an electrode material other than Al. In general, when the electrode width is W / λ = 0.25, that is, when the ratio between the electrode width and the inter-electrode space is 1: 1, the most effective coupling coefficient is high and a broadband characteristic is obtained. When the electrode material is Al, the electrode thickness at which the reflection amount becomes zero when W / λ = 0.25 is H / λ = 0.03, and when used in the low frequency band, the thickness is 1 μm or more. It must be made thicker, and the production efficiency will deteriorate. Therefore, when the film thickness must be reduced, the electrode material may be Cu, Ag, or Au. For example, when the electrode material is Cu, as shown in FIG. 5, the electrode film thickness at which the reflection amount becomes zero when W / λ = 0.25 is H / λ = 0.005, which is much higher than that of Al. In addition, it is possible to satisfy both the conditions of a thin film thickness, a high coupling coefficient, and zero reflection, thereby realizing a filter characteristic with a wider band and a smaller in-band deviation.

  The case where the electrode material is a single material has been described so far, but an alloy in which Al, Cu, Mg, Ag, Au, and other metals are combined may be used. In that case, it is preferable that 90 wt% or more of any of Al, Cu, Mg, Ag, and Au is contained. It goes without saying that the SAW converter of the present invention can be applied to SAW devices other than transversal SAW filters.

The basic section of the surface acoustic wave converter concerning the present invention is shown. The relationship between the electrode width and the amount of reflection when the electrode material is Al is shown. The passage characteristic when the electrode material is Al is shown. The relationship between the electrode width when the electrode material is Mg and the amount of reflection is shown. The relationship between the electrode width and the amount of reflection when the electrode material is Cu is shown. The relationship between the electrode width and the amount of reflection when the electrode material is Ag is shown. The relationship between the electrode width and the reflection amount when the electrode material is Au is shown. The transversal type | mold SAW filter comprised by the conventional single electrode is shown. (A) shows a split (double) electrode, and (b) shows DART. (A) shows a simplified diagram when an external matching circuit is attached to the SAW filter, and (b) shows an equivalent circuit diagram of the comb-shaped electrode. A comparison of each electrode structure and electrical Q is shown. The transmission characteristic of the transversal type SAW filter comprised by the conventional single electrode is shown.

Explanation of symbols

1: Positive electrode finger 2: Negative electrode finger 31: Piezoelectric substrate 32, 33: SAW converter 34: Shield electrode 35: Sound absorbing material

Claims (6)

A surface acoustic wave converter for constituting a surface acoustic wave device by being arranged on a 128 ± 5 ° rotated Y-cut X-propagating lithium niobate substrate,
The surface acoustic wave converter has a configuration in which a plurality of basic sections having a width corresponding to the wavelength λ of the surface acoustic wave to be excited are connected.
The basic section has one positive electrode finger and one negative electrode finger, and the positive electrode finger and the negative electrode finger are arranged so that the center-to-center distance is approximately λ / 2.
When the electrode material of the surface acoustic wave converter is Al or an alloy containing Al as a main component, the relationship between the electrode film thickness H / λ normalized by the wavelength λ and the electrode width W / λ is expressed as H / λ < 0.38 ≦ W / λ <0.42 when 0.01, 0.22 ≦ W / λ <0.42 when 0.01 ≦ H / λ ≦ 0.03, and 0.03 < A surface acoustic wave transducer characterized in that 0.08 <W / λ ≦ 0.25 when H / λ.   When the electrode material of the surface acoustic wave converter is Mg or an alloy containing Mg as a main component, the relationship between the electrode film thickness H / λ normalized by the wavelength λ and the electrode width W / λ is expressed as H / λ < When 0.02, 0.28 ≦ W / λ <0.42, and when 0.02 ≦ H / λ ≦ 0.03, 0.20 ≦ W / λ ≦ 0.30, and 0.03 < 2. The surface acoustic wave transducer according to claim 1, wherein 0.08 <W / λ ≦ 0.22 when H / λ.   When the electrode material of the surface acoustic wave converter is Cu or an alloy containing Cu as a main component, the relationship between the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ is expressed as H / λ < 2. When 0.005 is satisfied, 0.25 ≦ W / λ <0.42, and when 0.005 ≦ H / λ is satisfied, 0.08 <W / λ ≦ 0.30. A surface acoustic wave transducer according to claim 1.   When the electrode material of the surface acoustic wave converter is Ag or an alloy containing Ag as a main component, the relationship between the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ is expressed as H / λ < 2. When 0.005 is satisfied, 0.30 ≦ W / λ <0.42, and when 0.005 ≦ H / λ is satisfied, 0.08 <W / λ ≦ 0.35. A surface acoustic wave transducer according to claim 1.   When the electrode material of the surface acoustic wave transducer is Au or an alloy containing Au as a main component, the relationship between the electrode film thickness H / λ and the electrode width W / λ normalized by the wavelength λ is expressed as H / λ < 2. When 0.005 is satisfied, 0.18 ≦ W / λ <0.42, and when 0.005 ≦ H / λ is satisfied, 0.08 <W / λ ≦ 0.25. A surface acoustic wave transducer according to claim 1. A surface acoustic wave device in which at least one surface acoustic wave transducer according to claim 1 is disposed.

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