JPH02268012A - Surface acoustic wave circuit - Google Patents

Abstract

PURPOSE:To improve etching liquid to pass through electrodes well, to prevent charging between electrodes opposite to each other effectively and to improve the characteristic by short-circuiting interdigital electrodes opposite to each other with wires in a surface acoustic wave circuit in which plural interdigital electrodes are provided on a substrate with a surface acoustic wave propagates thereupon. CONSTITUTION:Interdigital electrodes of reflector electrodes 1, 4 are separated completely so that they are not in contact with each other by air gap 17 thereby causing etching liquid to flow between the inlet and exist of a path between bus bars 2 opposite to each other in any direction. Thus, a pattern with high accuracy is obtained and the charging between parts 1a and 2a and between parts 1b and 2b opposite to each other in the bus bar 2 of the electrode 1 is prevented by using short-circuiting wires 6, 7 respectively. The air gap of the reflector electrode is designed wider than the air gap 17 of the exciting electrode and it is desired to reduce the effect of the reflection by diffusion. Moreover, the bus bar 2 may be split in plural numbers in its lengthwise direction and the split parts and opposite parts may be connected by wires 7-9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface acoustic wave circuit used as a reflector electrode of a surface acoustic wave resonator or a dummy electrode of a matched filter.

[Conventional technology]

FIG. 3 is a pattern diagram showing a surface acoustic wave element disclosed in, for example, Japanese Patent Application Laid-Open No. 63-211910. In the figure, 1 and 4 are reflector electrodes, 2 is a bus bar, 3 is an excitation electrode, and 5 is a The bus bar 10 at 2 is a substrate, and the short bus bar 17 at 15 and 16 is a gap.

Next, the operation will be explained. The surface acoustic wave emitted from the excitation electrode 3 propagates to both sides and is reflected by the reflector electrodes 1 and 4. The short bus bars 15 and 16 are provided to prevent deterioration of resonance characteristics caused by charging of the reflector electrodes 1 and 4 due to the electric field. The gap 17 is provided to improve the passage of etching solution between the electrodes and to improve electrical characteristics by maintaining correspondence with the excitation electrode.

[Problem to be solved by the invention]

Since the conventional surface acoustic wave circuit is configured as described above, the propagation speed of the surface acoustic wave becomes faster in the portions 1b and 2b of the electrode 1 and the busbar 2 because the surface acoustic wave passes through the short busbar 15. , the charging effect fades,
The characteristics will deteriorate. Furthermore, as the number of pairs of reflector electrodes increases, the passage of the etching solution near the short bus bar 15 becomes difficult. Particularly, when etching between patterns with short intervals, the etching solution stagnates in the part where one side is blocked, making it impossible to etch the pattern according to the dimensions. This tendency is particularly noticeable when the pattern is thick.

Since the conventional surface acoustic wave resonator is constructed as described above, there have been problems such as poor passage of the etching solution and a reduction in the effectiveness of the short bus bar, resulting in deterioration of characteristics.

The present invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a surface acoustic wave circuit that can improve the passage of etching solution and can effectively prevent electrification. With the goal.

[Means to solve the problem]

The surface acoustic wave circuit of the present invention has a structure in which a short bus bar is eliminated and mutually opposing comb-shaped electrodes are short-circuited with a wire. The number of shorting wires may be one or more.

[For production]

By short-circuiting the comb-shaped electrodes facing each other with a wire, the etching solution can flow better than when using a conventional short bus bar, and charging between the opposing electrodes is effectively prevented, resulting in better characteristics. A surface acoustic wave circuit is obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 and 4 are reflector electrodes, 2 is a bus bar,
3 is an excitation electrode, 5 is a second busbar, 6.7.8.9 is a shorting wire, 1o is a substrate, and 17 is a gap. The short-circuiting wires 6.7 short-circuit between the mutually opposing bus bars 2, 2 of the reflector electrode 1, and the short-circuiting wires 8, 9 short-circuit between the mutually opposing bus bars 5, 5 of the reflector electrode 4. do.

Next, the operation will be explained. Since the comb-wave electrodes of the reflector electrodes 1 and 4 are completely separated from each other by a gap 17 so that they do not come into contact with each other, the etching liquid flows between the inlet and outlet of the passage between the mutually facing busbars. It can also flow smoothly in the direction of , forming highly accurate patterns. Also, the opposing portion 1 of the bus bar 2 of the reflector electrode l
Electrification between a and 23 and between 1b and 2b can be prevented by shorting with shorting wires 6 and 7, respectively, and good characteristics can be obtained. The gap 17 in the reflector electrode is the gap 17 in the excitation electrode.
It is desirable to make the distance wider than that to reduce the influence of reflection due to dispersion.

Note that, as shown in FIG. 2, if the bus bar 2 is divided into a plurality of parts along its length, the passage of the etching solution can be further improved.

In this case, the divided portion is connected to the opposing portion with the wire 6.
Connect by 7, 8.9. Furthermore, by using the ground terminal of the package, there is no need for wires to run over the board 10.

〔Effect of the invention〕

As described above, according to the present invention, since the comb-shaped electrodes facing each other are connected by wires, it is possible to improve the passage of the etching solution and form a highly accurate pattern. It will be done.

Furthermore, since the connecting point between the comb-shaped electrode and the wire can be freely selected, deterioration of characteristics due to charging can be prevented by effective short circuiting.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a pattern of a surface acoustic wave circuit according to an embodiment of the present invention, FIG. 2 is a similar plan view showing an embodiment of the present invention, and FIG. 3 is a plan view of a conventional surface acoustic wave circuit. FIG. 3 is a plan view showing a pattern. 1.4...Reflector electrode, 2...Bus bar, 3...
Excitation electrode, 5...-second bus bar, 6. 7. 8.
9... Short circuit wire, 10... Board, 17...
void. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Patent applicant: Mitsubishi Electric Corporation [3. The detailed description of the amendment is amended as follows.

Claims (1)

[Claims] An elastic surface comprising a surface acoustic wave circuit comprising a substrate for propagating surface acoustic waves and a plurality of comb-wave electrodes formed on the substrate, characterized in that the opposing comb-wave electrodes are short-circuited by a wire. wave circuit.