JPH10190402A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide surface acoustic wave device whose frequency characteristic is small in change with lapse of time and which has high reliability. SOLUTION: Although this surface acoustic wave device connects a surface acoustic wave element 11 with a package 12 through an adhesive layer 16, the layer 16 is one-sidely provided on one of short sides of the element 11 of the layer 16 and more than half of the element 11 is floated up from a mounting plane 14. Then, even though a volumetric change occurs when the adhesive layer is stiffened, etc., the transformation of the surface acoustic wave element is drastically reduced. The floating part of the element 11 is also mechanically supported by connecting it to the package 12 through bonding wires 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device, and more particularly to a surface acoustic wave device used for a cable TV, a keyless entry device for an automobile, a mobile communication, and the like.

[0002]

2. Description of the Related Art Conventionally, surface acoustic wave devices used for various mobile communications such as a cable TV, a keyless entry for an automobile, and a simple type mobile phone have been required to have higher frequency accuracy than system requirements, Quartz substrates with little dependence are often used.

In a surface acoustic wave device, an IDT (Inter Digital Transdu) is provided on a piezoelectric substrate.
It is necessary to fix a surface acoustic wave element on which an electrode pattern including cer) is formed to a package. For fixing the surface acoustic wave element to the package, for example, the surface acoustic wave element and the package are opposed to each other via an adhesive (mounting agent), and the adhesive is cured by heating to about 150 to 200 degrees. By doing that.

FIG. 9 is a perspective view schematically showing an example of the configuration of a conventional surface acoustic wave device. A surface acoustic wave element 903 in which an electrode pattern 902 including an IDT, a reflector and the like are formed on a piezoelectric substrate 901 by a conductive thin film and the like, and an envelope 904
Are fixed with an adhesive or the like, and the connection terminal 905 of the envelope 904 and the connection terminal 902a of the surface acoustic wave element formed as a part of the electrode pattern 902 of the surface acoustic wave element are connected by, for example, a bonding wire (not shown). And
Hermetically sealed with a metal cap 906 or the like.

FIG. 10 is a diagram schematically showing a cross-sectional structure in the AA direction of the surface acoustic wave device. The illustration of the metal cap is omitted. The surface acoustic wave element and the envelope are fixed with an adhesive 907. In the case of a general thermosetting adhesive, the adhesive is cured at a temperature of about 200 ° C. to about 300 ° C. The adhesive changes in volume upon curing, and for example, a general thermosetting resin shrinks by about 20%. Due to such a change in the volume of the adhesive, a thermal load in the manufacturing process, a difference in the coefficient of thermal expansion of the package, the adhesive, and the piezoelectric substrate, stress is applied to the surface acoustic wave element. Deforms into a convex shape with a displacement of about several tens of μm (when the size of the piezoelectric substrate is about 2 mm × 3 mm and the thickness is about 0.5 mm). FIG.
FIG. 1 is a diagram for explaining deformation of a surface acoustic wave element due to stress. As shown in FIG. 11A, when the adhesive layer contracts, a stress acts on the adhesive surface of the surface acoustic wave element (piezoelectric substrate) 10 in the contracting direction, and the surface on the side opposite to the adhesive surface has a surface. Stress is generated in the direction of extension, and the shape is deformed into a convex shape. Thereafter, the chip is gradually flattened by the release of the residual stress remaining in the surface acoustic wave element (FIG. 11B, FIG. 11).
(C)).

Due to the change in the shape of the surface acoustic wave element accompanying the release of the residual stress, there is a problem that the characteristics of the surface acoustic wave device, particularly the frequency characteristics, change with time. For example, when the surface acoustic wave element is deformed as shown in FIG. 11A, the distance between the electrode fingers of the IDT is widened, and the frequency characteristic is greatly changed. Further, the frequency characteristics also change due to the deformation of the surface acoustic wave element accompanying the release of the residual stress as shown in FIGS. 11B and 11C. FIG. 12 is a graph showing an example of the change over time of the frequency characteristic of such a conventional surface acoustic wave device. That is, after the surface acoustic wave element is mounted on the package, the center frequency rises because the surface acoustic wave element deforms in a convex shape, but the center frequency decreases because it gradually flattens over time. The decrease of the center frequency extends to several tens of kHz, which deviates from the standard of the center frequency of the surface acoustic wave device, and causes a problem of lowering the yield and lowering the quality and reliability.

[0007] Such a change in the characteristics of the surface acoustic wave device not only lowers the productivity but also degrades the performance of the device. FIGS. 13 and 14 are diagrams for explaining changes in frequency characteristics due to deformation of the surface acoustic wave element. For example, the pass frequency band shifts in a surface acoustic wave filter, and the oscillation frequency shifts in a surface acoustic wave resonator.

In particular, in a surface acoustic wave device provided with a surface acoustic wave resonator that oscillates at a specific frequency, it is a serious problem that the characteristic frequency that should oscillate when the residual stress is released is shifted. For example, in various security devices such as a keyless entry system for an automobile, access is performed by oscillating a specific frequency instead of a conventional mechanical key. In such a device, when the oscillation frequency changes over time, for example, in a keyless entry system, there is a problem that an accessible distance becomes large or access becomes impossible.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a surface acoustic wave device having a small change over time and having stable frequency characteristics. Another object of the present invention is to provide a surface acoustic wave device having a structure with high productivity with a small change over time in frequency characteristics.

Another object of the present invention is to provide a highly reliable surface acoustic wave device suitable for a keyless entry device or the like, in which the oscillation frequency does not change with time.

[0011]

The surface acoustic wave device according to the present invention employs the following structure to solve the above-mentioned problems. A surface acoustic wave device according to the present invention has a first surface and a second surface, and a surface acoustic wave element in which an electrode pattern having an IDT for exciting a surface acoustic wave is formed on the first surface; A package having a mounting surface on which the surface acoustic wave element is mounted, a connection terminal provided around the mounting surface, and a connection terminal to the surface acoustic wave element; and an area in which substantially half or more of the surface acoustic wave element is mounted. An adhesive layer disposed between the second surface of the surface acoustic wave element and the mounting surface of the package so as to float from the surface, and the surface acoustic wave of the first surface of the surface acoustic wave element. In a region where the element is floating from the package, an electrode pattern of the surface acoustic wave element is electrically connected to a connection terminal of the package, and a connection is maintained so as to maintain an interval between the surface acoustic wave element and the package. Connection means And wherein the door.

The ID of the first surface of the surface acoustic wave device
A region where T is formed is shifted from a region where the adhesive layer is provided on the second surface of the surface acoustic wave element.

Further, the electrode pattern has a reflector for reflecting the surface acoustic wave, and a region of the first surface of the surface acoustic wave device where the reflector is formed, and the bonding of the second surface to the second surface. It is characterized in that at least part of the region is opposed to the region where the layer is provided.

The adhesive layer may be formed on any one of a first side and a second side of the second surface of the surface acoustic wave element that intersect the direction of excitation of the surface acoustic wave on the second surface. It is characterized by being unevenly distributed in the vicinity of one side.

Further, the electrode pattern may be formed in a region of the second surface of the surface acoustic wave element where the adhesive layer is not provided.

Further, a wiring pattern may be formed in a region of the mounting surface where the adhesive layer is not provided.

A surface acoustic wave device according to the present invention has a first surface and a second surface, and an ID for exciting a surface acoustic wave to the first surface.
A surface acoustic wave element on which an electrode pattern having T is formed, a package having a mounting surface on which the surface acoustic wave element is mounted, and a region that is substantially half or more of the surface acoustic wave element floats from the mounting surface. Second of the surface acoustic wave device
And an adhesive layer disposed between the surface of the package and the mounting surface of the package, and the second surface of the surface acoustic wave device or the mounting surface of the package floating from the mounting surface of the surface acoustic wave device. And supporting means formed to support the portion.

The ID of the first surface of the surface acoustic wave element
A region where T is formed is shifted from a region where the adhesive layer is provided on the second surface of the surface acoustic wave element.

Further, the electrode pattern has a reflector for reflecting the surface acoustic wave, and a region of the first surface of the surface acoustic wave device where the reflector is formed, and the bonding of the second surface to the second surface. It is characterized by being opposed to the region where the layers are arranged.

The adhesive layer may be formed on any one of a first side and a second side of the second surface of the surface acoustic wave element, the second side being substantially perpendicular to the direction of excitation of the surface acoustic wave on the second surface. It is characterized by being unevenly distributed in the vicinity of one side.

That is, in the surface acoustic wave device of the present invention, in order to reduce the stress deformation of the surface acoustic wave element, the bonding area between the surface acoustic wave element and the adhesive layer is reduced. When the bonding area between the surface acoustic wave element and the adhesive layer is reduced, the bonding strength between the surface acoustic wave element and the package is also reduced.However, in the present invention, the surface acoustic wave element is supported by a bonding wire or a projection provided on the package. Solving the problem of strength. It is preferable that the bonding area between the surface acoustic wave element and the adhesive layer be as small as possible as long as the required bonding strength can be maintained. In order to maintain the reliability of the surface acoustic wave device, at least the bonding surface of the surface acoustic wave element Of 20
% May be provided with the adhesive layer. When the surface acoustic wave element is substantially rectangular, the adhesive layer is disposed so as to be biased to one of a pair of short sides of the surface acoustic wave element. When the surface acoustic wave element has a reflector (grating), an adhesive layer may be provided on the back surface of the region where the grating is formed.

This is because the volume change of the adhesive layer, the piezoelectric substrate,
This is for minimizing the influence of the stress deformation of the surface acoustic wave element due to the difference in linear expansion coefficient between the constituent materials of the electrode pattern and the constituent materials of the package. The present inventors examined changes in frequency characteristics (including changes over time) by changing the area and arrangement position of the adhesive layer. As a result, even when stress deformation of the surface acoustic wave element occurred, it was not reflected. It was found that the frequency characteristics of the surface acoustic wave device were not significantly affected if they remained in the region where the vessel was formed. Therefore, in the surface acoustic wave device of the present invention, it is most preferable that the adhesive layer is disposed so as not to overlap with the electrode pattern of the IDT, the reflector and the like. Layers may be provided.

Further, a bonding wire may be used as the connection means of the surface acoustic wave device according to the present invention. The bonding wires may connect the input / output bonding pads of the IDT or the grounding bonding pads of the reflector to the package, or a dummy which does not particularly contribute to the electrical connection for supporting the surface acoustic wave element. The electrodes may be provided on the surface acoustic wave element and connected. Further, for example, by changing the shape, thickness, and material of the bonding wire, a bonding wire having a strength larger than that required for electrical connection may be used.

The means for supporting the surface acoustic wave element is not limited to the bonding wire. For example, the surface of the package (envelope) on which the surface acoustic wave element is mounted may have a height substantially equal to the thickness of the adhesive layer after curing. A projection having the same may be formed, and the projection may support the surface acoustic wave element. The shape of the projection may be designed as required, such as a point, a line, a plane, or the like. Further, a bonding wire and a projection may be used in combination as a support means of the surface acoustic wave element.

Further, in the surface acoustic wave device of the present invention, there is a region where the surface of the surface acoustic wave element and the package are separated from each other. Therefore, such a region, that is, a region where the adhesive layer is not provided on the back surface of the electrode pattern forming surface of the surface acoustic wave element or the package mounting surface can be effectively used. Usually, a package has a laminated structure of several layers, and a wiring pattern or the like is formed on the surface of each layer to form a capacitance or an inductance or to form a ground pattern. According to the surface acoustic wave device of the present invention, since many parts of the surface acoustic wave element are raised from the surface of the package on which the surface acoustic wave element is mounted, various wiring circuits are formed in this part, and capacitance and inductance are formed. Or a ground pattern can be formed. Therefore, the mounting density can be improved, and the degree of freedom of mounting can be improved.
The number of stacked packages can be reduced, productivity can be improved, and manufacturing costs can be reduced.

[0026]

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

(Embodiment 1) FIG. 1 is a view schematically showing a configuration of a surface acoustic wave device according to the present invention. FIG. 2 is a top view of the surface acoustic wave device. FIG. 3 is a diagram schematically illustrating a cross-sectional structure of the surface acoustic wave device in the AA direction, and FIG. 4 is a diagram schematically illustrating a cross-sectional structure of the surface acoustic wave device in the BB direction. In FIG. 1, the electrodes of the surface acoustic wave element are not shown, and the adhesive layer is shown to show its position, but is not actually seen from above. This surface acoustic wave device has a surface acoustic wave element 11 mounted on a package 12 and an IDT 13 for exciting a surface acoustic wave on one surface.
a surface acoustic wave element 11 on which an electrode pattern 13 including a is formed, a mounting surface 14 on which the surface acoustic wave element 11 is mounted,
The surface acoustic wave element 11 is provided around the mounting surface 14.
Between the surface acoustic wave element 11 and the mounting surface 14 of the package so that a region that is substantially half or more of the surface acoustic wave element 11 floats from the mounting surface 14. Adhesive layer 16 disposed on
In the surface of the surface of the surface acoustic wave element 11 on which the electrode pattern 13 is formed, the surface of the electrode pattern 13 of the surface acoustic wave element 11
And a bonding wire 17 for electrically connecting the surface acoustic wave element 11 and the package 12 while maintaining a distance d between the surface acoustic wave element 11 and the package 12.

The surface acoustic wave element 11 exemplified here is a one-port type surface acoustic wave resonator, and an IDT 13a for exciting a surface acoustic wave and an IDT 13a are sandwiched between the IDT 13a in the direction in which the surface acoustic wave is excited by the IDT 13a. 1 arranged
And a pair of reflectors 13b (gratings).
The IDT 13a is composed of a pair of comb-shaped electrodes which are arranged to mesh with each other. The surface acoustic wave element 11 used a quartz substrate as the piezoelectric substrate, and used aluminum as the electrode pattern. Although an epoxy-based thermosetting resin is used as the adhesive layer 16 here, various adhesive materials (including a conductive resin) such as a silicone-based resin and a silver-epoxy-based resin may be used as necessary. Can be. The surface 14 for mounting the surface acoustic wave element of the package 12 is metallized, and a connection terminal 15 for connection with the surface acoustic wave element 11 is provided.
a, 15b, 15c, 15d, 15e, 15f, respectively, and bonding wires 17a, 17b, 1
7c, 17d and 17f indicate the ID of the surface acoustic wave element 11.
It is connected to T13a and the reflector 13b. Connection terminal 15
c and 15d are respectively connected to the comb-shaped electrodes of the IDT 13a of the surface acoustic wave element 11, and function as input / output terminals for signals to the IDT 13a. Connection terminals 15a, 15
b, 15e, and 15f are at the ground potential, and are connected to the reflector 13b of the surface acoustic wave element 11.

The surface opposite to the surface on which the IDT 13a and the reflector 13b are formed and the mounting surface 1 of the package 12
4 is disposed to face with an adhesive layer 16 interposed therebetween. That is, the surface acoustic wave element 11 and the package 12 are
6 are joined. In the surface acoustic wave device according to the present invention, the adhesive layer is disposed so that a region that is substantially half or more of the surface acoustic wave element 11 floats from the mounting surface 14, and the elastic layer is disposed in a region where the adhesive layer 16 is not disposed. Surface wave device 1
1 and the mounting surface 14 of the package 12 are separated while maintaining the thickness d of the adhesive layer (see FIGS. 3 and 4). Adhesive layer 16
Are arranged to be biased along one short side of the surface acoustic wave element 11, and no adhesive layer is provided on the back surface of the area where the IDT 13 a of the surface acoustic wave element 11 is formed. Therefore, one side of the surface acoustic wave element 11 is not fixed by the adhesive layer 16, and the stress generated due to the curing of the adhesive 16 or the like can be released. Therefore, the stress remaining in the surface acoustic wave element 11 can be suppressed to a minimum, and the surface acoustic wave element is hardly deformed.

On the other hand, in a region not supported by the adhesive layer 16 of the surface acoustic wave element 11, bonding wires 17a for connecting the surface acoustic wave element 11 and the package 12 are provided.
Reference numerals 17b, 17c, and 17d not only make an electrical connection between the surface acoustic wave element 11 and the package 12, but also make a mechanical connection. For example, assuming now that the mounting surface 14 of the package 12 is arranged horizontally and the surface acoustic wave element 11 is disposed above the surface via the adhesive layer 16, the surface acoustic wave element 11 becomes cantilevered. Since the portion of the surface acoustic wave element 11 that is not supported by the adhesive layer 16 is pulled toward the mounting surface 14 by gravity, a moment is generated, and at the same time, a stress is also generated inside the surface acoustic wave element 11. . In the surface acoustic wave device of the present invention,
By supporting the surface acoustic wave element 11 with the bonding wires 17a, 17b, 17c and 17d, the bonding strength between the surface acoustic wave element 11 and the package 12 can be maintained.

It is preferable that the area of the surface of the surface acoustic wave element 11 where the adhesive layer 16 is provided is as small as possible.
It is sufficient that the necessary bonding strength is obtained in combination with the support by zero. Depending on the shape and size of the surface acoustic wave element 11, the adhesive strength of the adhesive layer 16, etc., the present inventors consider that if about half of the area of the surface acoustic wave element 11 is floating from the mounting surface 14, It has been found that the deformation of the element 11 due to stress is greatly reduced. In addition, when a commonly used mounting agent such as an epoxy-based, silicone-based, or silver-epoxy-based mounting agent is used, about 20
It has been found that the required strength can be obtained if about 30% is adhered. When the application area of the adhesive was less than 20%, the fluctuation of the center frequency was improved to several kHz, but the adhesive strength of the surface acoustic wave element was weak and the surface acoustic wave element was peeled off.

The surface acoustic wave device of the present invention can minimize the deformation of the surface acoustic wave element 11 due to the hardening of the adhesive layer 16 by adopting such a configuration.
Further, the change in the frequency characteristics of the surface acoustic wave device can be almost eliminated.

The present inventors measured the variation of the center frequency of the surface acoustic wave device with respect to the elapsed time after mounting the surface acoustic wave element 11. FIG. 5 is a diagram showing the change over time of the frequency characteristics of the surface acoustic wave device of the present invention illustrated in FIGS. The center frequency f ₀ variation was improved within the range of several KHz. As described above, the surface acoustic wave device according to the present invention includes the adhesive layer 1
Since the stress acting on the surface acoustic wave element 11 is minimized by the hardening of No. 6, the residual stress on the surface acoustic wave element 11 can be reduced, and the shape change of the surface acoustic wave element 11 can be extremely small. Can be. Therefore, the stability and reliability over time of the frequency characteristics of the surface acoustic wave device can be improved.

Further, the present inventors prepared a type of adhesive using, for example, a silicone type, an epoxy type, a silver epoxy type or the like, and tried the same measurement as in FIG. Showed extremely small and stable frequency characteristics.

(Embodiment 2) FIG. 6 is a diagram schematically showing another example of the configuration of the surface acoustic wave device of the present invention. In FIG. 6, the electrodes of the surface acoustic wave element are not shown. In the surface acoustic wave device illustrated in FIG. 1, portions not supported by the adhesive layer 16 are supported by bonding wires.
In the surface acoustic wave device shown in FIG.
Is provided with a projection 20 for supporting the surface acoustic wave element 11,
The projections 20 also support the surface acoustic wave element 11.

That is, this surface acoustic wave device has a surface acoustic wave element 11 mounted on a package 12, and has a surface on which an electrode pattern 13 including an IDT 13a for exciting a surface acoustic wave is formed. 11, a package 12 having a mounting surface 14 on which the surface acoustic wave element 11 is mounted, and a mounting surface for mounting the surface acoustic wave element 11 and the package so that a region of at least half of the surface acoustic wave element 11 floats from the mounting surface 14. 14, an adhesive layer 16 disposed between
The mounting surface 14 of the package 12 includes a projection 20 formed to support a portion separated from the mounting surface 14 of the surface acoustic wave element 11.

The surface acoustic wave device 11 exemplified here is shown in FIG.
Is a one-port type surface acoustic wave resonator similar to that described above, and includes an IDT 13a for exciting a surface acoustic wave, and a pair of reflectors 13b arranged so as to sandwich the IDT 13a in the direction of excitation of the surface acoustic wave by the IDT 13a. (Grating). The IDT 13a is composed of a pair of comb-shaped electrodes which are arranged to mesh with each other. The surface 14 for mounting the surface acoustic wave element of the package 12 is metallized, and the connection terminals 15a, 15b, 15
c, 15d, 15e, and 15f, respectively, and bonding wires 17a, 17b, 17c, 17d, 1
7e and 17f, the IDT 13 of the surface acoustic wave element 11
a, connected to the reflector 13b. Connection terminal 15c, 1
5d is connected to the comb-shaped electrode of the IDT 13a of the surface acoustic wave element 11, and functions as a signal input / output terminal for the IDT 13a. Connection terminals 15a, 15b, 15
e and 15f are at the ground potential and are connected to the reflector 13b of the surface acoustic wave element 11.

The surface opposite to the surface on which the IDT 13a and the reflector 13b are formed and the mounting surface 1 of the package 12
4 is disposed to face with an adhesive layer 16 interposed therebetween. That is, the surface acoustic wave element 11 and the package 12 are
6 are joined. In the surface acoustic wave device according to the present invention, the adhesive layer is disposed so that a region that is substantially half or more of the surface acoustic wave element 11 floats from the mounting surface 14, and the elastic layer is disposed in a region where the adhesive layer 16 is not disposed. Surface wave device 1
1 and the mounting surface 14 of the package 12 are separated while maintaining the thickness d of the adhesive layer. The adhesive layer 16 is a surface acoustic wave element 1
1, the adhesive layer is not arranged on the back surface of the surface of the surface acoustic wave element 11 where the IDT 13a is formed.

On the other hand, in a region of the surface acoustic wave element 11 that is not supported by the adhesive layer 16, the surface acoustic wave element 11 is supported by a projection 20 formed on the mounting surface 14 of the package 12. Although this projection supports the surface acoustic wave element 11, it is not joined to the surface acoustic wave element 11, so that the surface acoustic wave element 11 can freely move on the projection 20. Therefore, the surface acoustic wave element 11 can be supported without deformation even when the adhesive layer 16 is cured. The shape of the projection 20 may be determined as needed. For example, the surface acoustic wave element may be supported by a point-like projection, or the surface acoustic wave element may be supported by a linear projection or a flat projection. (See FIGS. 7 and 8). The height of the projection 20 from the mounting surface 14 may be set to be substantially equal to the thickness of the adhesive layer 16. When the volume of the adhesive layer 16 changes (shrinks or expands) due to curing, it is preferable to set the thickness of the adhesive layer after curing to be equal to the height of the protrusion.

Here, the projections 20 are connected to the package 12
Although the example in which the protrusion 20 is formed on the mounting surface 14 has been described, the same effect can be obtained by forming the protrusion 20 on the second surface of the surface acoustic wave element 11, that is, the surface facing the mounting surface 14. it can.

In the surface acoustic wave device of the present invention having the projections 20 as described above, the adhesive layer is provided so that a region of at least half of the surface acoustic wave element 11 floats from the mounting surface 14. In the region where the layer 16 is not arranged, the thickness d of the adhesive layer is held by the protrusion 20 between the surface acoustic wave device 11 and the mounting surface 14 of the package 12. Adhesive layer 1
Numeral 6 is arranged so as to be biased along one short side of the surface acoustic wave element 11, and no adhesive layer is provided on the back surface of the surface of the surface acoustic wave element 11 where the IDT 13a is formed. Therefore, one side of the surface acoustic wave element 11 is not fixed by the adhesive layer 16, and the stress generated due to the curing of the adhesive 16 or the like can be released. Therefore, the stress remaining in the surface acoustic wave element 11 can be suppressed to a minimum, and the surface acoustic wave element is hardly deformed.

In the surface acoustic wave device of the present invention in which the surface acoustic wave element 11 is supported by the adhesive layer 16 and the projections 20, the surface acoustic wave element 11 is
Is not required to be mechanically supported, so that the degree of freedom in designing the position of the bonding connection, the electrode pattern of the surface acoustic wave element 11, and the like can be increased.

Further, as described in the first embodiment, the bonding wires 17a, 17b, 17c for connecting the surface acoustic wave element 11 and the package 12 in a region not supported by the adhesive layer 16 of the surface acoustic wave element 11. , 17d
Thus, the electrical and mechanical connection between the surface acoustic wave element 11 and the package 12 may be performed.

[0044]

As described above, in the surface acoustic wave device of the present invention, the joint area between the surface acoustic wave element and the adhesive layer is reduced, and the stress generated in the surface acoustic wave element when the adhesive layer is cured is greatly reduced. can do. Therefore, the surface acoustic wave device of the present invention has a very small residual stress in the surface acoustic wave element, and can substantially eliminate the deformation of the surface acoustic wave element due to the release of the residual stress and the temporal change in the frequency characteristics.

The surface acoustic wave device of the present invention can stabilize the frequency characteristics and can be used in a factory with high reliability.

Further, according to the surface acoustic wave device of the present invention, an electrode pattern or the like can be formed in a region where the surface acoustic wave element is lifted from the package. Therefore, the surface acoustic wave device of the present invention can be downsized, and at the same time, the mounting density can be improved, the degree of freedom of mounting can be improved, and the number of stacked packages can be reduced, and Performance and manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of the configuration of a surface acoustic wave device according to the present invention.

FIG. 2 is a top view of the surface acoustic wave device of FIG. 1;

FIG. 3 is a diagram schematically showing a cross-sectional structure in the AA direction of the surface acoustic wave device of the present invention.

FIG. 4 is a diagram schematically showing a cross-sectional structure in the BB direction of the surface acoustic wave device of the present invention.

FIG. 5 is a diagram showing a change over time in frequency characteristics of the surface acoustic wave device according to the present invention.

FIG. 6 is a diagram schematically showing another example of the configuration of the surface acoustic wave device according to the present invention.

FIG. 7 is a diagram schematically showing another example of the configuration of the surface acoustic wave device of the present invention.

FIG. 8 is a diagram schematically showing another example of the configuration of the surface acoustic wave device according to the present invention.

FIG. 9 is a perspective view schematically showing an example of the configuration of a conventional surface acoustic wave device.

FIG. 10 is a diagram schematically showing a cross-sectional structure in the AA direction of the surface acoustic wave device of FIG. 9;

FIG. 11 is a view for explaining deformation of the surface acoustic wave element due to stress.

FIG. 12 is a graph showing an example of a change over time in frequency characteristics of a conventional surface acoustic wave device.

FIG. 13 is a diagram illustrating a change in frequency characteristics due to deformation of the surface acoustic wave element.

FIG. 14 is a diagram illustrating a change in frequency characteristics due to deformation of the surface acoustic wave element.

[Explanation of symbols]

10 piezoelectric substrate 11 surface acoustic wave element 12 package (envelope) 13a IDT 13b reflector 14 mounting surface 15a, 15b, 15c, 15d, 15e, 15f ......
Connection terminal 16 Adhesive layer 17a, 17b, 17c, 17d, 17f Bonding wire 20 Projection

Continued on the front page (72) Inventor Norio Murakawa 23-1,975-1, Minami 5-Jo-dori, Asahikawa-shi, Hokkaido Toshiba Hokuto Electronics Co., Ltd. Electronics Co., Ltd.

Claims (11)

[Claims] 1. A surface acoustic wave element having a first surface and a second surface, and an electrode pattern having an IDT for exciting a surface acoustic wave is formed on the first surface; And a package disposed around the mounting surface and having a connection terminal to the surface acoustic wave element, wherein a region of substantially half or more of the surface acoustic wave element floats from the mounting surface. An adhesive layer disposed between a second surface of the surface acoustic wave element and a mounting surface of the package; and the first surface of the surface acoustic wave element, wherein the surface acoustic wave element is the package. Connecting means for electrically connecting an electrode pattern of the surface acoustic wave element and a connection terminal of the package in a region floating from the surface of the surface acoustic wave element and for maintaining a space between the surface acoustic wave element and the package; It is characterized by having Surface acoustic wave device. 2. The first surface of the surface acoustic wave device according to claim 1, wherein
2. The surface acoustic wave device according to claim 1, wherein a region where the DT is formed and a region where the adhesive layer is provided on the second surface of the surface acoustic wave element are displaced. 3. 3. The surface acoustic wave device according to claim 1, wherein the electrode pattern has a reflector for reflecting the surface acoustic wave, and a region of the first surface of the surface acoustic wave device where the reflector is formed, and the bonding of the second surface. 3. The surface acoustic wave device according to claim 1, wherein at least a part of the surface acoustic wave device faces a region where the layer is provided. 4. The adhesive layer according to claim 1, wherein the adhesive layer is formed on any one of a first side and a second side of the second surface of the surface acoustic wave element that intersects a direction in which the surface acoustic wave is excited on the second surface. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is unevenly distributed near one side. 5. The surface acoustic wave device according to claim 1, wherein said connection means is a bonding wire. 6. The elastic surface according to claim 1, wherein the electrode pattern is formed in a region of the second surface of the surface acoustic wave element on which the adhesive layer is not provided. Wave device. 7. The surface acoustic wave device according to claim 1, wherein a wiring pattern is formed in a region of the mounting surface where the adhesive layer is not provided. 8. A surface acoustic wave element having a first surface and a second surface, and an electrode pattern having an IDT for exciting a surface acoustic wave is formed on the first surface; A package having a mounting surface for mounting the surface acoustic wave element, between the second surface of the surface acoustic wave element and the mounting surface of the package so that an area of about half or more of the surface acoustic wave element floats from the mounting surface. An adhesive layer disposed on the second surface of the surface acoustic wave element or a mounting surface of the package, the supporting means being formed to support a portion floating from the mounting surface of the surface acoustic wave element; A surface acoustic wave device comprising: 9. The I surface of the first surface of the surface acoustic wave element.
The surface acoustic wave device according to claim 8, wherein a region where the DT is formed is different from a region where the adhesive layer is provided on the second surface of the surface acoustic wave element. 10. The electrode pattern has a reflector that reflects the surface acoustic wave, and the adhesion of the region of the first surface of the surface acoustic wave device where the reflector is formed and the bonding of a second surface. The surface acoustic wave device according to claim 8, wherein the surface acoustic wave device faces a region where the layer is provided. 11. The adhesive layer is formed on one of a first side and a second side of the second surface of the surface acoustic wave element, the direction being substantially perpendicular to the direction of excitation of the surface acoustic wave on the second surface. The surface acoustic wave device according to claim 8, wherein the surface acoustic wave device is unevenly distributed near one side.