JPH11308072A - Surface acoustic wave element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, with a simple structure, a surface acoustic wave element which is miniaturized. SOLUTION: Two sets of resonator patterns 20 and 28 which consists of comb-shaped electrodes 14 and 22 mutually facing opposite to each other and two reflectors 16, 18, 24 and 26 which are provided on both sides of the electrodes 14 and 22 are installed on a piezoelectric substrate 12. An input electrode 48 connected to one of the comb-shaped electrode 14 of each resonator pattern and a output electrode 56 connected to the other comb-shaped electrode 22 of each resonator pattern are arranged between the patterns 20 and 28, each reflector 18 and 24 is respectively connected to a ground electrode 32 in each of the resonator patterns, and the electrode 32 is arranged between the patterns 20 and 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency filter for extracting electromagnetic waves in a specific frequency band, and more particularly to a surface acoustic wave device using a surface acoustic wave.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, two pairs of comb-shaped electrodes 3 are provided on a piezoelectric substrate 1 made of quartz or the like via a connecting portion 2 connected in cascade, as shown in FIG. On both sides of each of the comb-shaped electrodes 3, reflectors 4 each having a grid pattern formed at an equal pitch are arranged at four positions.

An input electrode 5 connected to the comb-shaped electrode 3 and an output electrode 6 are formed on the side edges of the substrate 1, respectively. In addition, ground electrodes 7 are provided at four locations, and ground electrodes 8 are also provided on the substrate 1 between the reflectors 4.
It is connected to and provided.

As described above, the input / output electrodes 5 and 6 and the four ground electrodes 7 are formed as electrodes connected to the ceramic package, and the ground electrode 8 is formed between the reflectors 4 so as to enhance the shielding effect. Was.

[0005]

In the case of the above conventional technology, a high performance and small surface acoustic wave element is required in accordance with recent miniaturization and sophistication of electronic equipment. Is to reduce the number of comb-shaped electrodes 3 provided on the substrate 1 and the number of reflectors 4
And the area of the ground electrodes 7 and 8 must be reduced. However, this has a problem that the frequency characteristics of the surface acoustic wave filter deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a surface acoustic wave element which can be reduced in size with a simple structure.

[0007]

A surface acoustic wave element according to the present invention comprises a piezoelectric substrate, a comb-shaped electrode facing each other,
Two resonator patterns each including two reflectors provided on both sides of the comb-shaped electrode are arranged in parallel. An input electrode connected to one comb-shaped electrode of each resonator pattern and an output electrode connected to the other comb-shaped electrode of each resonator pattern are arranged between the resonator patterns. Are connected to the ground electrode for each of the resonator patterns, and the ground electrode is arranged between the resonator patterns.

The input electrode and the output electrode each include a bonding electrode portion and an inspection electrode portion. Similarly, the ground electrode also includes a bonding electrode portion and an inspection electrode portion.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a surface acoustic wave device 10 according to one embodiment of the present invention, in which two pairs of comb-shaped electrodes are formed on a surface of a substrate 12 having a piezoelectric property such as quartz or lithium tantalate by using a metal thin film such as aluminum or an aluminum alloy. 14 are provided alternately facing each other. On both sides of the comb-shaped electrode 14, reflectors 16 and 18 each having a grid-like pattern formed of a conductor of a metal thin film such as aluminum or an aluminum alloy at an equal pitch are provided. Then, the comb-shaped electrode 14 and the pair of reflectors 1
6, 18 form a set of resonator patterns 20.

On the other hand, a comb-shaped electrode 22 and a resonator pattern 28 having two reflectors 24 and 26 are provided beside the resonator pattern 20, and a connecting portion 30 is provided between the comb-shaped electrodes 14 and 22. Formed and connected to each other.

Between each of the resonator patterns 20 and 28 and on both sides of the connecting portion 30, reflectors 18 and 2 are provided, respectively.
4 are provided with ground electrodes 32 and 34.
The ground electrode 32 has a rectangular bonding electrode portion 36.
And an inspection electrode section 37, and these electrode sections 36,
37 is connected by a connection part 38. The bonding electrode portion 36 is followed by an elongated rectangular shield pattern 40 toward the connection portion 30. The ground electrode 32 is connected to the reflector 18 on the side of the bonding electrode portion 36.

Similarly, the ground electrode 34 is also composed of a rectangular bonding electrode portion 42 and an inspection electrode portion 43, and a connecting portion 44 provided between these electrode portions 42, 43. Then, from the bonding electrode portion 42 to the connection portion 30
The shield pattern 46 extending in the direction of is provided, and is connected to the reflector 24 on the side of the bonding electrode portion 42.

An input electrode 48 is provided between the resonator patterns 20 and 28 and outside the ground electrode 32. The input electrode 48 is also connected to the ground electrodes 32, 3
4 includes a bonding electrode part 50 and an inspection electrode part 51 having the same shape as that of No. 4, and a connection part 52 provided between these electrode parts 50 and 51. The bonding electrode portion 50 is connected to a wiring portion 54 parallel to the outer periphery of the reflector 18 without being connected to the reflector 18, and is connected to the wiring portion 54.
Are connected to the outside of the comb-shaped electrode 14.

On the outside of the other ground electrode 34,
An output electrode 56 is provided. This output electrode 56 also
A bonding electrode portion 58 and an inspection electrode portion 59 having the same shape as the input electrode 48, and these electrode portions 58, 5
9 and a connecting portion 60 provided between the connecting portions. Output electrode 56
Are connected to a wiring portion 62 connecting the bonding electrode portion 58 and the comb-shaped electrode 22. The wiring portion 62 is formed parallel to the outer periphery of the reflector 24 without being connected to the reflector 24, and Is connected to the outside.

As shown in FIG. 2 (a), the elastic surface of the embodiment has a package 6 made of ceramic or the like.
4 and bonded by wire bonding to connect the ground electrodes 32, 34, the input electrode 48, the output electrode 50, and each electrode 66 formed on the side edge of the package 64 with a wire 68 such as a gold wire. It is connected.

Each of the electrodes 32,
As shown in FIG. 2B, 34, 48, 50
Contrary to (a), the electrodes 66 and the wires 68 of the package 64
The input electrode 48 provided on the package 64
The arrangement of the output electrode 50 and the output electrode 50 may be either, and can be adapted to each.

Here, detection electrodes 37, 43, 51, provided on the earth electrodes 32, 34 and the input / output electrodes 48, 50,
When the surface acoustic wave element 10 is inspected, the surface 59 is scratched due to a prog, so that the bonding with the wire 68 fails. Therefore, the wire 56
Bonding electrodes 36, 42, 50, 58
Is provided separately.

The elastic surface of this embodiment, like the element 10, has the resonator patterns 20 formed on both ends of the substrate 12,
28, the input / output 48, 50 and the ground electrode 32, 3
By providing 4, the overall shape can be reduced and the number of elements per wafer can be increased.

The surface acoustic wave device according to the present invention is not limited to the above embodiment, and the sizes of the detection electrode and the bonding electrode may be changed, and each electrode may be made of a conductive material. It can be changed as appropriate.

[0020]

The surface acoustic wave device of the present invention has a small size as a whole by providing an input / output electrode and a ground electrode in the middle between the resonator patterns on the substrate, thereby reducing the number of devices that can be taken per wafer. In addition, the input / output electrodes and the electrodes of the package which are wire-bonded with the wires can support both input and output.

[Brief description of the drawings]

FIG. 1 is a plan view of a surface acoustic wave device according to an embodiment of the present invention.

FIGS. 2A and 2B are a plan view of a package including a surface acoustic wave device according to an embodiment of the present invention and a plan view of another package according to the embodiment; FIGS.

FIG. 3 is a plan view of a conventional surface acoustic wave device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Surface acoustic wave element 12 Substrate 14,22 Comb-shaped electrode 16,18,24,26 Reflector 20,28 Resonator pattern 30,38,44,52,60 Connection part 32,34 Earth electrode 36,42,50,58 Bonding electrode part 37, 43, 51, 59 Inspection electrode part 48 Input electrode 54, 62 Wiring part 56 Output electrode

Claims (3)

[Claims] 1. On a piezoelectric substrate, two sets of resonator patterns each comprising a comb-shaped electrode facing each other and two reflectors provided on both sides of the comb-shaped electrode are arranged in parallel. An input electrode connected to one comb-shaped electrode of each of the resonator patterns and an output electrode connected to the other comb-shaped electrode of each of the resonator patterns are arranged between the resonator patterns. A surface acoustic wave element connected to a ground electrode for each resonator pattern, and the ground electrode is arranged between the resonator patterns. 2. The surface acoustic wave device according to claim 1, wherein each of the input electrode and the output electrode comprises a bonding electrode portion and an inspection electrode portion. 3. The surface acoustic wave device according to claim 1, wherein each of said ground electrodes comprises a bonding electrode portion and an inspection electrode portion.