JPS6181013A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To prevent the degradation of characteristics due to the distortion of the wave surface and the occurrence of disconnection accidents of electrode fingers and to obtain a surface acoustic wave device of good yield by providing a dummy electrode for a weighting electrode and providing a narrow conductive pattern connected to a leading-out electrode along the apodize. CONSTITUTION:A dummy electrode 14 is formed on a piezoelectric substrate 11 to constitute a comb-shaped electrode. A narrow conductive pattern 15 formed along the apodize is connected to a weighting electrode 12 and dummy electrode 14 and is connected to a leading-out electrode 13 together with electrodes 12 and 14. The conductive pattern 15 is formed with a line width equal to or as about twice as long as the line width of electrode fingers. Though this narrow pattern is provided on a surface acoustic wave propagation path, the distortion of the wave surface is hardly generated, and influences upon characteristics are recognized. Meanwhile, even if disconnection occurs in the part between the conductive pattern 15 along the apodize and the leading-out electrode 13, characteristics are not affected because the conductive pattern 15 and the leading-out electrode 13 are connected, and the yield is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a surface acoustic wave device used in video equipment such as television receivers and video tape recorders, communication equipment, and the like.

Conventional technology In recent years, surface acoustic wave devices have been increasingly used in video equipment 1 to reduce the number of parts and improve quality in communications equipment, etc., but the demand for even higher performance and lower costs has increased. It's coming.

Below, we will explain Rokukashi's surface acoustic wave device using the drawings shown in Figure 141.

FIGS. 2 and 3 are plan views of elements of a conventional surface acoustic wave device, respectively. In FIGS. 2 and 3, 1 is a piezoelectric substrate, 2 is a weighting electrode, and 3 is an extraction electrode.

Further, 4 is a dummy electrode.

Problems to be Solved by the Invention However, in the surface acoustic wave device configured as shown in FIG. pass below. Since the propagation speed of surface acoustic waves when there is a conductive thin film on the piezoelectric substrate 1 is smaller than the propagation speed of the free surface, the wavefront is distorted and the output characteristics are deteriorated. On the other hand, in the structure in which dummy electrodes 4 are provided as shown in Figure 3, deterioration of characteristics due to distortion of the wavefront can be avoided, but since the length of each comb-shaped electrode becomes long, the line width becomes thinner, especially at high frequencies. , yield reduction is likely to occur due to wire breakage.

In view of the above drawbacks, it is an object of the present invention to eliminate characteristic deterioration due to wavefront distortion and at the same time improve yield.

Means for Solving the Problem In order to achieve this object, the surface acoustic wave device of the present invention includes a dummy electrode on the weighting electrode (1) and a thin conductive pattern connected to the extraction electrode along its apodization. It has a configuration that includes.

Function: In the surface acoustic wave device of the present invention, the thin conductive pattern 7 connected to the extraction electrode along the apodization of the weighting electrode having the dummy electrode is provided.
Differences in propagation speed of surface acoustic waves depending on location are significantly reduced or eliminated. Even if the electrode fingers of the comb-shaped electrode are long and the line width thereof is narrow, there is no risk of disconnection due to the presence of the conductive pattern.

1. Embodiment,' Fig. 1 is a plan view of a surface acoustic wave filter that is an embodiment of the present invention.

In the figure, 11 is a piezoelectric substrate, 12 is a weighting electrode, 13 is an extraction electrode, and 14 is a dummy electrode, which are formed on the piezoelectric substrate 11 to constitute a comb-shaped electrode. Reference numeral 16 denotes a thin conductive pattern formed along the avocado, and is connected to the electrodes 12 and 14 and to the extraction electrode 13 together with them. The conductive pattern 16 is created with a line width that is at least twice the line width of the electrode finger. Even if such a thin pattern is provided in the surface acoustic wave propagation path, almost no wavefront distortion occurs, and no influence on the characteristics is observed. On the other hand, even if a disconnection occurs at the part sandwiched between the conductive pattern 15 along the apodization and the extraction electrode 13, the conductive pattern 15 is connected to the extraction electrode 13, so the characteristics are not affected and the yield is reduced. improves.

Effects of the Invention As described above, in the present invention, a weighting electrode or a dummy electrode is provided, and a thin conductive pattern connected to an extraction electrode is provided on top of the weighting electrode along the apodization, so that characteristic deterioration due to wavefront distortion does not occur. In addition, the occurrence of electrode finger disconnection accidents can be prevented, and surface acoustic wave devices with high yield can be obtained, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a surface acoustic wave filter which is an embodiment of the present invention, and FIGS. 2 and 3 are plan views of a conventional surface acoustic wave device. 11...Piezoelectric substrate, 12...Weighting electrode, 13...Extraction electrode, 14...
- Dummy electrode, 16... conductive pattern. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2

Claims (1)

[Claims] A dummy electrode connected to an extraction electrode is provided on the weighting electrode of the comb-shaped electrode provided on the piezoelectric substrate, and a thin conductive pattern is further provided along the apodization thereof and connected to the extraction electrode. Surface acoustic wave device.