JPH10209800A - Surface-acoustic-wave device and surface-acoustic-wave device package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve signal attenuation characteristic outside a band by airtightly sealing a surface-acoustic-wave element, which has comb-shaped electrodes for transmission and reception formed on the surface of a piezoelectric substrate and a package which has a ground conductor pattern divided into regions, corresponding to comb- shaped electrodes for transmission and reception at the bottom part where the surface acoustic wave element is mounted. SOLUTION: On the surface of the bottom part of a ceramic-made surface-acoustic- wave device packet 2, ground conductor patterns 24 and 25 which are divided through a nonconductor part 27 and electrically insulated are formed. At the dotted-line position of the bottom part of this packet 2, a surface-acoustic-wave element 1 is mounted, which has two couples of comb-shaped electrodes 12 and 13 for transmission and comb-shaped electrodes 14 and 15 for reception on the 1st surface of the piezoelectric substrate 11. For this mounting, a silicone adhesive is used to adhere them, lead-out electrodes 61 to 64 of the comb-shaped electrodes 12 to 15 are connected to connection parts 81 to 84, and the package 2 is sealed airtightly with a metal cap. Consequently, unnecessary signals outside the band are further attenuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface acoustic wave device, and more particularly to a surface mount type surface acoustic wave device.

[0002]

2. Description of the Related Art Conventionally, an electronic component functioning as a so-called filter, such as a surface acoustic wave device, which selects and extracts only a desired signal from a signal source emitting a plurality of types of signals is called a "package". A surface acoustic wave device is mounted in a container via a mounting agent, and the semiconductor device is electrically connected to input / output terminals provided on a package.

For example, taking a surface acoustic wave filter as an example, as shown in FIG. 8A, this surface acoustic wave filter is made of a surface acoustic wave element 1 and a ceramic material on which the surface acoustic wave element 1 is mounted. Package 2, metal cap 4, and metal cap 4 and package 2
And a sealing material 3 made of a metal such as Kovar for hermetically sealing between the upper surface 21 and the upper surface 21.

In this surface acoustic wave element 1, one or more pairs of transmitting comb electrodes 6 and one or more pairs of receiving comb electrodes 7 are provided on one side of a piezoelectric substrate 5 with a predetermined distance D.
The transmission comb electrodes 6 and 7 are, as shown in a partially enlarged view in FIG. 8B, a comb-shaped electrode 61 and a comb-shaped electrode identical thereto. The portions corresponding to the teeth of the comb are formed in a non-contact and meshing state with the electrodes 62 and 62 facing each other, and the portions of the electrodes 61 and 62 corresponding to the so-called teeth of the comb are arranged at an accurate pitch P1. . Similarly, the portion corresponding to the comb teeth of the receiving comb-teeth electrode has a pitch P2 (not shown).
Are arranged at intervals.

On the other hand, on the surface of the bottom portion 22 of the package 2, a ground conductor pattern 23 for grounding the transmitting and receiving comb-teeth electrodes formed on the surface acoustic wave element 1 is formed. Are electrically connected to each other by wire bonding.

The ground conductor pattern 23 formed on the surface of the bottom 22 of the package 2 is subjected to electrolytic nickel plating and electrolytic gold plating on tungsten metallization.

Here, the ground conductor pattern 23 formed on the bottom 22 of the conventional surface acoustic wave device is
And the ground conductor pattern 23 is electrically disposed so as to function as a common ground electrode without distinction between the transmitting side and the receiving side of the surface acoustic wave element 1. ing.

The characteristics of the surface acoustic wave filter are as follows: only a desired signal is extracted from a signal from a signal source including a plurality of signals, and other unnecessary signals, that is, signals outside the band are removed or reduced. It is most important that the attenuation characteristic for a signal outside the band (hereinafter, the attenuation characteristic for the signal outside the band may be simply referred to as “attenuation characteristic”) is good.

However, the conventional surface acoustic wave device such as a surface acoustic wave filter having the above structure has a problem that it does not have satisfactory attenuation characteristics.

Further, as another problem, when the surface acoustic wave element is mounted on the surface acoustic wave device package, non-uniform stress acts on the surface acoustic wave element, causing a frequency shift and a fluctuation in bandwidth. There is a problem that the characteristics of the surface acoustic wave device are adversely affected. Of the above conventional problems,
The following reasons can be considered as causes that the attenuation characteristics cannot be sufficiently obtained. That is, the electric signal originally sent from the signal source to the transmitting comb-teeth electrode includes an out-of-band signal that should be removed before reception on the receiving side. The surface electrode is once converted into a surface acoustic wave by a tooth electrode, and a surface acoustic wave propagation region between the outside of the transmitting comb-teeth electrode and the outside of the receiving comb-teeth electrode (hereinafter, this surface acoustic wave propagation region is simply referred to as a “propagation region”). Is to be removed or attenuated when passing through.

However, in the conventional surface acoustic wave device having the above-mentioned structure, since the transmitting comb electrode and the receiving comb electrode share the ground conductor pattern for grounding, the out-of-band signal Is transmitted to the receiving comb-teeth electrode side via this ground conductor pattern, and as a result, a signal outside this band is transmitted to the output side. It is believed that there is.

The cause of the stress acting on the surface acoustic wave element is that the thermal expansion coefficient and the thermal contraction rate are different among the mounting agent, the piezoelectric substrate of the surface acoustic wave element, the ground conductor pattern, and the package. Therefore, it is considered that a stress on the surface acoustic wave element is generated due to these differences, and the cause of the non-uniformity of the stress is considered to be a variation in the application shape and the application amount of the mounting agent.

When a stress acts on the surface acoustic wave element, deformation such as warpage occurs in the piezoelectric substrate, and the deformation causes a distance D between the transmission-side comb-teeth electrode 6 and the reception-side comb-teeth electrode 7. And the pitch P1 between the teeth of the transmission-side comb-tooth electrode and the pitch P2 between the teeth of the reception-side comb-tooth electrode fluctuate. Is considered to occur.

[0014]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a surface acoustic wave device and a surface acoustic wave device package having good signal attenuation characteristics outside the band of the surface acoustic wave element.

A second object of the present invention is to provide a surface acoustic wave device and a surface acoustic wave device capable of suppressing the application of uneven stress to the surface acoustic wave device when the surface acoustic wave device is mounted. To provide a package.

[0016]

According to a first aspect of the present invention, there is provided a surface acoustic wave device comprising at least one pair of transmitting comb-shaped electrodes and at least one pair of receiving electrodes on a surface of a piezoelectric substrate. Surface acoustic wave element on which a comb-shaped electrode for use is formed, and the surface acoustic wave element is mounted on the bottom, and a region corresponding to a comb-shaped electrode for transmission and a comb-shaped electrode for reception are provided on the bottom. The package includes a package in which a ground conductor pattern divided into regions is formed, and means for hermetically sealing the surface acoustic wave element mounted in the package.

According to a second aspect of the present invention, in the surface acoustic wave device according to the present invention, the ground conductor pattern has a surface acoustic wave propagation region between the transmitting comb electrode and the receiving comb electrode in the propagation direction of the surface acoustic wave. Is divided substantially parallel to the surface acoustic wave propagation direction, and is divided in a direction outside the surface acoustic wave propagation region with respect to the surface acoustic wave propagation direction in a direction substantially orthogonal to the surface acoustic wave propagation direction. It is characterized by.

According to a third aspect of the present invention, there is provided a surface acoustic wave device according to the present invention, wherein the transmitting comb electrode and the receiving comb electrode are each two pairs.

According to a fourth aspect of the present invention, there is provided a surface acoustic wave device comprising a piezoelectric substrate, at least one pair of transmitting comb-teeth electrodes disposed on the first surface of the piezoelectric substrate, and at least one pair of receiving comb electrodes. And a ground conductor pattern disposed on the second surface of the piezoelectric substrate and divided into a region corresponding to the transmitting comb-teeth electrode and a region corresponding to the receiving comb-teeth electrode. It is characterized by having.

According to a fifth aspect of the present invention, in the surface acoustic wave device according to the present invention, the ground conductor pattern has a surface acoustic wave propagation region between the transmitting comb electrode and the receiving comb electrode in the propagation direction of the surface acoustic wave. Is divided substantially parallel to the surface acoustic wave propagation direction, and is divided in a direction outside the surface acoustic wave propagation region with respect to the surface acoustic wave propagation direction in a direction substantially orthogonal to the surface acoustic wave propagation direction. It is characterized by.

According to a sixth aspect of the present invention, there is provided a surface acoustic wave device package having at least a pair of transmitting comb electrodes and at least a pair of receiving comb electrodes formed on a surface of a piezoelectric substrate. A package body having a bottom on which the element is mounted; and a ground conductor pattern formed on the bottom of the package body and divided into a region corresponding to a comb-shaped electrode for transmission and a region corresponding to a comb-shaped electrode for reception. And characterized in that:

A surface acoustic wave device package according to a seventh aspect of the present invention is characterized in that the transmitting comb electrode and the receiving comb electrode are each two pairs.

Here, the region divided into the region corresponding to the transmission comb-teeth electrode and the region corresponding to the reception comb-teeth electrode means that the transmission comb-teeth electrode of the ground conductor pattern is formed. The part to be grounded and the part to which the comb electrode for reception is grounded are electrically separated, meaning that they are kept insulated from each other.

As a concrete method of dividing the ground conductor pattern, a portion of the ground conductor pattern where the transmitting comb electrode is grounded and a portion where the receiving comb electrode is grounded are electrically connected. It is only necessary that they be divided in a specific manner, and there is no particular limitation. Therefore, for example, in addition to dividing the ground conductor pattern in a direction parallel to the surface acoustic wave propagation direction, the ground conductor pattern may be divided in a direction perpendicular to the surface acoustic wave propagation direction or in an oblique direction. May be.

Considering that the effect that the stress acting on the surface acoustic wave element can be made uniform can be obtained, the propagation direction of the surface acoustic wave between the transmitting comb-teeth electrode and the receiving comb-teeth electrode is considered. The region is divided substantially parallel to the direction of propagation of the surface acoustic wave, and the outer parts on both the left and right sides of the propagation region with respect to the direction of propagation of the surface acoustic wave are divided in a direction substantially orthogonal to the direction of propagation of the surface acoustic wave. It is preferable to divide the whole into two.

The structure of the surface acoustic wave device package according to the present invention is typically a base on which a surface acoustic wave element is mounted, for example, a bottom portion corresponding to a bottom plate of the surface acoustic wave device, and a surface acoustic wave device. It comprises a side wall constituting the outer peripheral portion of the device, and a cap disposed above the side wall and serving as a lid for sealing the surface acoustic wave device.

Here, regarding the structure of the package, the bottom portion and the side wall are formed of separate members, and the side wall is formed of a plurality of layers cut along a plane parallel to the bottom portion. It is possible to make the structure constituted by.

If such a so-called multi-layer structure is adopted as the package structure, necessary members and shapes can be provided for each layer, so that the side wall or the side wall and the bottom are integrally formed. Thus, a surface acoustic wave device package having a complicated shape and structure can be obtained.

For example, the package has a three-layer structure including a first layer, a second layer, and a third layer from the bottom, and the first layer located at the lowermost side has a bottom for metallizing the ground conductor pattern. The metal part of the ground conductor pattern is extended to the outer peripheral portion of the first layer to facilitate connection with an external terminal disposed outside the package. The two layers are provided with a shelf-like protrusion for forming a connection portion for connection with the terminal of the comb-teeth electrode formed on the piezoelectric substrate, and a metal thin film layer is formed on the upper surface of the shelf-like protrusion. A conductor portion for electrically connecting the metal thin film layer and an external terminal disposed outside the side wall is formed on the upper surface of the second layer, and the conductor portion is sandwiched above the second layer. It is conceivable that the third layer is laminated .

With such a multilayer structure, it is possible to obtain a package in which each of the ground conductor pattern and the connection portion can be easily electrically connected to an external terminal. Therefore, it is preferable that the package has a multilayer structure as described above.

In the surface acoustic wave device and the surface acoustic wave device using the surface acoustic wave device package according to the present invention, the ground conductor pattern is formed in the region corresponding to the transmitting comb electrode and the receiving comb electrode. Since the signal is divided into the corresponding regions, the out-of-band signal is prevented from being transmitted from the transmitting-side comb electrode to the receiving-side comb electrode via the ground conductor pattern. As a result, the out-of-band signal is effectively removed when propagating as a surface acoustic wave on the piezoelectric substrate from the transmitting-side comb-teeth electrode to the receiving-side comb-teeth electrode. Damping characteristics are improved.

Also, a surface acoustic wave device according to the present invention,
In a surface acoustic wave device using a surface acoustic wave device package, as a ground conductor pattern, a surface acoustic wave is propagated in a surface acoustic wave propagation region between a transmitting comb electrode and a receiving comb electrode with respect to the propagation direction of the surface acoustic wave. In the case where a portion divided in a direction substantially perpendicular to the direction of propagation of the surface acoustic wave is used in a region outside the surface acoustic wave propagation region with respect to the direction of propagation of the surface acoustic wave, Since uneven stress does not act on the surface acoustic wave element,
The occurrence of frequency deviation, bandwidth fluctuation, and the like caused by the non-uniform stress is prevented.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view of a surface acoustic wave filter according to the present invention, and FIG. 2 is a plan view of a package 2 of the surface acoustic wave filter according to the present invention viewed from the direction of arrow A in the figure. is there.

In the surface acoustic wave filter of this embodiment,
The surface acoustic wave device package 2 (hereinafter, this surface acoustic wave device package is abbreviated as “package”) has a frame-shaped second layer and a third layer laminated on a horizontal plate-like first layer. It has a three-layered structure, and has a rectangular shallow tray-shaped shape with a length of 4.8 mm × width 9.1 mm × thickness 1.8 mm,
These first to third layers are all formed of the same material ceramic.

Next, the structure of the package 2 will be described with reference to FIG. As shown in FIG. 2, ground conductor patterns 24 and 25 formed by metallization are formed on the surface of the bottom 22 of the package 2. The ground conductor pattern 24 and the ground conductor pattern 25 are It is divided via a non-conductive portion 27 passing substantially at the center, and is electrically insulated from each other.

The package 2 has a
A shelf-like connecting portion 8 is formed at both ends in the vertical direction inside, and a thin metal film is formed on the surface of the upper surface portion of the connecting portion 8 indicated by oblique lines in FIG. The connection parts 81, 82, 83 and 84 are electrically insulated.

On the other hand, as shown in FIG. 3, external terminals 91 to 94 and 101 for electrically connecting the inside and outside of the package 2 are provided on the outer peripheral portion of the side wall 26 of the package 2.
To 104 are provided. And the above-mentioned connection parts 81-
84 and these external terminals 101, 102, 103 and 104, the connection part 81 and the external terminal 101, the connection part 82 and the external terminal 103, the connection part 83 and the external terminal 10
2. The connection portion 84 and the external terminal 104 are electrically connected to each other.

The ground conductor pattern 24 is electrically connected to external terminals 91 and 93, and the ground conductor pattern 25 is electrically connected to external terminals 92 and 94.

Next, the relationship between the package and the surface acoustic wave filter element mounted in the package will be described with reference to FIG.

As shown in FIG.
2, the surface acoustic wave filter element 1 is mounted. The surface acoustic wave filter element 1 includes a piezoelectric substrate 11
Are formed with two sets of transmitting comb-teeth electrodes 12 and 13 and two sets of receiving comb-teeth electrodes 14 and 15.

The position where the surface acoustic wave filter element 1 is mounted on the package 2 is a rectangular portion shown by a dotted line in the figure. The second surface of the surface acoustic wave filter element 1, that is, the surface opposite to the surface on which the transmitting and receiving comb-teeth electrodes 12 to 15 are formed, is adhered on the bottom 22 via a silicone adhesive.

Next, the extraction electrodes 61 to 64 of the comb electrodes 12 to 15 are connected to the connection portions 81 to 84 by wire bonding, and are connected to the extraction electrode 61 and the connection portion 81 and to the extraction electrode 62. Part 83, extraction electrode 64 and connection part 82, extraction electrode 63 and connection part 84
Are connected to each other.

In the surface acoustic wave filter of this embodiment,
The ground conductor pattern formed on the bottom portion 22 of the package 2 is divided via a non-conductor portion 27, and these are electrically disconnected. Therefore, the electric signal from the signal source is transmitted to the transmitting extraction electrodes 61 and 62.
FIG. 3 in which the transmission comb electrode is grounded
The signal flowing to the upper left ground conductor pattern 24 does not flow to the lower right ground conductor pattern 25 in FIG. As a result, out of the electrical signals from the signal source, out-of-band signals are prevented from flowing from the transmitting side to the receiving side via the ground conductor patterns 24 and 25. Therefore, such out-of-band signals are transmitted to the comb-teeth electrode 12,
As a result of being removed or attenuated when passing through the path from 13 to the surface of the piezoelectric substrate 11 and then to the receiving comb-teeth electrodes 14 and 15, it is hardly transmitted to the receiving side, so that signals outside this band are not transmitted. The attenuation characteristic is significantly improved as compared with the conventional surface acoustic wave filter.

In the surface acoustic wave filter of the present embodiment, as shown in FIG. 3, the ground conductor pattern is divided into two parts 24 and 25 via a non-conductor part 27. At positions outside the horizontal direction in the figure from the positions where the comb-tooth electrodes 12, 13, 14, and 15 are formed, the non-conductive parts 28 and 29 which are connected to both ends of the non-conductive part 27 and extend in the vertical direction in the figure, respectively. Are vertically divided in the figure.

Here, the transmitting / receiving comb-teeth electrodes 12 to 15 on the surface acoustic wave filter element 1 and the ground conductor pattern 24,
The positional relationship with 25 will be described.

The ground conductor patterns 24 and 25 have the same “L” shape, and these are non-conductor portions 27, 2
It is arranged at a position facing the Tomoe shape via 8 and 29. Then, these ground conductor patterns 24, 25
Is divided approximately parallel to the direction of surface acoustic wave propagation in the surface acoustic wave propagation region between the transmitting comb electrode and the receiving comb electrode with respect to the direction of surface acoustic wave propagation. The region outside the surface acoustic wave propagation region is divided in a direction substantially orthogonal to the surface acoustic wave propagation direction.

That is, the length of the non-conductive portion 27 dividing the ground conductor patterns 24 and 25 in the propagation direction of the surface acoustic wave, that is, the horizontal direction in the figure, is equal to the length in the horizontal direction in the figure. From the left end of the receiving comb-teeth electrode 14,
15 is larger than the distance W to the right end of the package 15, and when the surface acoustic wave filter 1 is bonded and mounted at a position surrounded by a dotted line on the bottom portion 22 of the package 2, the transmitting and receiving comb-teeth electrodes 12 to 15 are non-conductive. The conductor portion 27 is disposed at a position inside the left and right ends in the drawing. Therefore, this non-conductive portion 2
7, the non-conductive portion 29 which is coupled to the non-conductive portion 27 at the left end in the drawing is disposed further to the left than the left end of the transmitting comb-teeth electrodes 12 and 13 in the drawing. The non-conductive portion 28 coupled to the non-conductive portion 27 is disposed further to the right than the right ends in the drawing of the receiving comb electrodes 14 and 15.

As described above, the surface acoustic wave propagation area from the left ends of the transmitting comb electrodes 12 and 13 to the right ends of the receiving comb electrodes 14 and 15 where the surface acoustic waves propagate on the piezoelectric substrate is a non-conductive portion. The non-conductive portions 28 and 29 are located on the right and left sides of the surface acoustic wave propagation region in the drawing.

As a result, even if a stress acts on the surface acoustic wave filter element 1 in the horizontal direction in the drawing, the ground conductor patterns 24 and 25 are uniformly arranged in the horizontal direction in the drawing in the surface acoustic wave propagation region. Therefore, the stress acting on the surface acoustic wave filter element 1 in this region becomes uniform.

Further, since the non-conductive portions 28 and 29 are respectively arranged on both outer sides of the surface acoustic wave propagation region, the non-conductive portions 28 and 29 reduce the stress acting in the left-right direction in the drawing.

Therefore, even if a stress acts on the surface acoustic wave filter element 1 in the left-right direction in the figure, it is considered that the stress acts uniformly on the whole surface acoustic wave filter element 1 in the left-right direction in the figure. . As a result, it is possible to prevent the occurrence of a trouble such as a frequency shift or a fluctuation in bandwidth, which is caused by an uneven stress acting on the surface acoustic wave filter element as in the conventional surface acoustic wave filter.

FIG. 4 is a plan view showing another embodiment of the package. This package 2a differs from the above-described package 2 in the form of division of the ground conductor patterns 24a and 25a. That is, the non-conductive portion 27a substantially at the center of the conductive pattern is formed in a direction orthogonal to the propagation direction of the surface acoustic wave, and the non-conductive portions 28a and 29a near both sides of the conductive pattern connected to the non-conductive portion 27a It is shaped in the direction of wave propagation. Package 2a of this configuration
When a damping characteristic was examined using a surface acoustic wave device equipped with the above, it was confirmed that the same high damping characteristic as in the above embodiment was exhibited.

Next, the following comparative experiments were conducted to confirm the effects of the present invention.

In order to confirm the effect of dividing the ground conductor pattern of the package into the transmission side and the reception side, a ground conductor pattern which is formed uniformly over the entire mounting portion of the surface acoustic wave filter element and is not divided is used. A formed package having a conventional structure (see FIG. 5) and a package having a divided ground conductor pattern according to the present invention (see FIG. 2) were prepared. The size of each package was 4.8 × 9.1 × 1.8 mm. In the conventional package shown in FIG. 5, the connection portions 81 and 83 forming the input electrodes and the connection portions 82 and 84 forming the output electrodes are the same as those in the package shown in FIG. The difference is that they are not.

In each package, a resonator type obtained by patterning an aluminum alloy electrode on a quartz substrate as a surface acoustic wave element was used, using a silicone adhesive as a mount agent.

In this comparative experiment, the surface acoustic wave devices were fabricated from the same quartz wafer, and the structures other than the package were substantially the same.

The band characteristics of a surface acoustic wave filter assembled using a conventional package in which the ground conductor pattern is not divided are shown in graph 1 of FIG. 6 using the package according to the present invention in which the ground conductor pattern is divided. The band characteristics of the obtained surface acoustic wave filter are shown in graph 2 of FIG.

From these graphs, it can be seen that the surface acoustic wave filter according to the present invention has an improved attenuation in an unnecessary signal region outside the pass band as compared with the conventional surface acoustic wave filter.

Next, as shown in FIG. 2, a package provided with a ground conductor pattern divided at the center thereof in the longitudinal direction of the package, that is, substantially parallel to the propagation direction of the surface acoustic wave (hereinafter referred to as this Type (hereinafter referred to as "A type package") and a package (hereinafter referred to as a package) in which a ground conductor pattern is divided at its center in the direction of the short side of the package, that is, substantially perpendicular to the propagation direction of the surface acoustic wave. ,
This type is called "B type package". )
The two types of packages were prepared, and the surface acoustic wave device was assembled, and the characteristics as the surface acoustic wave device were evaluated.
Two types of packages prepared as comparative experiments are shown in FIGS. 2 and 4, respectively.

The characteristics of the surface acoustic wave device were largely changed after the mount cure, and were compared with the device before the cure.

The conditions for assembling the surface acoustic wave element were the same. The curing temperature at the time of mounting was 300 ° C. for 1.5 hours, which is strong against the change with time of the device characteristics. Also, a surface acoustic wave device with no stress applied to the mount without mounting was assembled for comparison.

The stress on the surface acoustic wave element was physically measured by a differential interferometer as the warpage of the surface acoustic wave element. The characteristics of the surface acoustic wave device due to stress were evaluated by measuring the bandwidth. Graph 3 shows the relationship between the device characteristics of the product without mount cure, the A type package product, and the B type package product and the warpage of the surface acoustic wave element. This graph shows that the surface acoustic wave element has no warpage in the product without mount cure, and that the bandwidth of this surface acoustic wave device is 540 KHz.
Also, it was found that the A-type package product was assembled with a small warpage and a wide bandwidth, whereas the B-type package product was large in the warpage, and accordingly the bandwidth was narrow and the variation was large.

From the results of the above comparative experiment, it was confirmed that the package according to the present invention was very effective in producing a surface acoustic wave device having stable characteristics by attenuating out-of-band unnecessary signals.

The present invention is not limited to the above embodiment.

For example, in the above embodiment, the surface acoustic wave device having the ground conductor pattern divided into the forms shown in FIGS. 2 and 4 has been described as an example, but the surface acoustic wave device or package according to the present invention is described. However, the present invention is not limited to those having the ground conductor pattern divided into these forms. That is, the ground conductor pattern may be divided between the transmitting side and the receiving side of the electrode such as a surface acoustic wave element. Therefore, in addition to those divided into the forms shown in FIGS. 2 and 4, for example, those divided diagonally in the diagonal direction of the package, or those divided into three or four or more parts It is also possible.

In the above embodiment, the surface acoustic wave filter has been described as an example. However, the present invention is not particularly limited to this, and may be any element provided with a transmitting electrode and a receiving electrode. . Therefore, the present invention can be applied to a surface acoustic wave device used as an element other than the surface acoustic wave filter, for example, as a delay line, a transmitter, an amplifier, or the like.

[0068]

As described in detail above, the use of the surface acoustic wave device and the package thereof according to the present invention provides a surface acoustic wave device in which unnecessary signals outside the band are further attenuated, It is possible to provide a stable surface acoustic wave device having a small variation in characteristics in the vicinity thereof, which greatly contributes to productivity.

Further, in the surface acoustic wave device according to the present invention or the surface acoustic wave device using the package thereof, the transmitting conductor and the receiving comb electrode in the propagation direction of the surface acoustic wave may be used as the ground conductor pattern. In the surface acoustic wave propagation region between, the surface acoustic wave is divided substantially parallel to the surface acoustic wave propagation direction, and the region outside the surface acoustic wave propagation region with respect to the surface acoustic wave propagation direction is substantially orthogonal to the surface acoustic wave propagation direction. In the case of using a device divided in the direction, it is possible to suppress the application of uneven stress to the mounted surface acoustic wave element.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an exploded view of a surface acoustic wave device according to the present invention.

FIG. 2 is a diagram showing a surface of the surface acoustic wave device according to the present invention as viewed from above;

FIG. 3 is a diagram showing a positional relationship when a surface acoustic wave element to be mounted on the package of the surface acoustic wave device according to the present invention is mounted.

FIG. 4 is a diagram showing the surface of the surface acoustic wave device used in Example 2 and the comparative experiment, as viewed from above.

FIG. 5 is a diagram showing the surface of the surface acoustic wave device used in the comparative experiment as viewed from above.

FIG. 6 is a diagram showing the attenuation characteristics of a surface acoustic wave device according to the present invention and the attenuation characteristics of a conventional surface acoustic wave device in the form of a signal waveform on the receiving side.

FIG. 7 shows the relationship between the stress acting on the surface acoustic wave element and the bandwidth of the surface acoustic wave device having the A type package and the surface acoustic wave device having the B type package used in the comparative experiment. Graph showing the correlation of

FIG. 8 is a perspective view showing an exploded view of a conventional surface acoustic wave device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface acoustic wave element 11 Piezoelectric substrate 12-15 Comb electrode 2 Surface acoustic wave device package 22 Bottom part 24, 25 Ground conductor pattern 26 Side wall.

Claims (7)

[Claims] 1. A surface acoustic wave element having at least a pair of transmitting comb-teeth electrodes and at least a pair of receiving comb-teeth electrodes formed on a surface of a piezoelectric substrate, and the surface acoustic wave element is mounted on a bottom portion. A package in which a ground conductor pattern divided into a region corresponding to a comb-shaped electrode for transmission and a region corresponding to a comb-shaped electrode for reception is formed on the bottom portion; and an elastic surface mounted in the package. Means for hermetically sealing the wave element. 2. The ground conductor pattern is divided substantially parallel to the surface acoustic wave propagation direction in the surface acoustic wave propagation region between the transmission comb electrode and the reception comb electrode with respect to the propagation direction of the surface acoustic wave. 2. The surface acoustic wave according to claim 1, wherein a region outside the surface acoustic wave propagation region with respect to the surface acoustic wave propagation direction is divided in a direction substantially orthogonal to the surface acoustic wave propagation direction. apparatus. 3. The surface acoustic wave device according to claim 1, wherein each of the transmitting comb electrode and the receiving comb electrode has two pairs. 4. A piezoelectric substrate; at least one pair of transmitting comb-teeth electrodes and at least one pair of receiving comb-teeth electrodes disposed on a first surface of the piezoelectric substrate; 2. A surface acoustic wave device, comprising: a ground conductor pattern arranged on a surface of the second surface and divided into a region corresponding to a comb-shaped electrode for transmission and a region corresponding to a comb-shaped electrode for reception. 5. The ground conductor pattern is divided substantially parallel to the surface acoustic wave propagation direction in the surface acoustic wave propagation region between the transmission comb electrode and the reception comb electrode with respect to the propagation direction of the surface acoustic wave. 4. The surface acoustic wave according to claim 3, wherein a region outside the surface acoustic wave propagation region with respect to the surface acoustic wave propagation direction is divided in a direction substantially orthogonal to the surface acoustic wave propagation direction. apparatus. 6. A package body having a bottom portion on which a surface acoustic wave element having at least a pair of transmitting comb electrodes and at least a pair of receiving comb electrodes formed on a surface of a piezoelectric substrate is mounted, and A surface acoustic wave device comprising a ground conductor pattern formed on a bottom portion of a package body and divided into a region corresponding to a transmission comb-teeth electrode and a region corresponding to a reception comb-teeth electrode. package. 7. The surface acoustic wave device package according to claim 6, wherein the transmitting comb electrode and the receiving comb electrode are each two pairs.