JPH04121121U - surface acoustic wave device - Google Patents

Abstract

(57) [Summary] [Purpose] To make the electrode fingers constituting the IDT electrode less likely to be disconnected due to discharge, and to minimize changes in characteristics even if the electrode fingers are disconnected. [Structure] In the IDT electrode 4, the electrodes 10 and 1
2 were connected to each other.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea can be applied to, for example, surface acoustic wave filters, surface acoustic wave resonators, surface acoustic wave delays, etc. Regarding surface acoustic wave devices such as wires, more specifically, constituting the IDT electrode thereof. The present invention relates to means for preventing electrode fingers from being disconnected due to discharge and changing their characteristics.

0002

[Conventional technology]

FIG. 3 schematically shows an example of a surface acoustic wave device. This surface acoustic wave device , for example, in the case of a surface acoustic wave filter, in which a surface wave substrate 2 such as a piezoelectric substrate is used. Two IDT electrodes 4, 4 for input/output are formed on the surface with a space between them. There is. Each IDT electrode 4 is a set of combs each having a plurality of electrode fingers 61 and 81. It consists of toothed electrodes 6 and 8 crossed.

0003 In such an IDT electrode 4, in order to realize desired amplitude characteristics and phase characteristics, For example, as shown by the virtual line A in FIG. There may be cases where the

0004 In addition, in order to increase the impedance of the IDT electrode 4, for example, As described in 1-225211, a sampling method is used. At zero excitation, multiple electrode fingers 61 and 81 with the same length are placed next to each other. It may be lined up in Figure 4 is an example of 1/3 sampling, with the same length Three electrode fingers 61 and 81 are arranged next to each other and arranged at regular intervals.

[0005] In addition, in order to further increase the apparent impedance, for example, as shown in FIG. In some cases, each electrode finger 61, 81 is divided into two electrodes. Electricity that does not split To distinguish between polar fingers and split electrode fingers, the former are called solid fingers, and the latter are called solid fingers. This is sometimes called a split finger.

[0006]

[Problem that the idea aims to solve]

In surface acoustic wave devices such as those described above, different potentials (i.e., different busbars) are used. Electrostatic charging may occur between the electrode fingers 61 and 81 (connected to the If the charged voltage at this time exceeds a certain value, for example at a part B in Figure 5, A discharge occurs, and the electrode fingers 61 and 81 are disconnected due to the Joule heat of the current flowing. Sometimes. In particular, the electrode fingers 61 and 81 are locally thin due to the effects of etching, etc. (for example, see section C in FIG. 5), the wire will be disconnected at that portion.

[0007] When such a disconnection occurs, the part beyond it, for example the part in Figure 5, It is said that the part 61e floats electrically, which disrupts the characteristics and causes a defect. There's a problem.

[0008] Therefore, this idea is to make the electrode fingers as described above less likely to break due to electric discharge. , and the main purpose is to minimize changes in characteristics even if the wire is disconnected.

[0009]

[Means to solve the problem]

In order to achieve the above purpose, the surface acoustic wave device of this invention is as described above. Connecting the tips of multiple adjacent electrode fingers with the same length using electrodes. It is characterized by

0010 In that case, the width of the electrode connecting the tips of the electrode fingers should be The width may be smaller than the width of the electrode.

[0011]

[Effect]

By doing the above, when a discharge occurs between electrode fingers at different potentials, the current will be The current flows in two directions: the base side of the electrode finger where electricity is generated, and the electrode side that connects the tip. Therefore, concentration of current is avoided and the electrode fingers are less likely to break. Also, the electrode finger may break. Even if the wire is wired, the part beyond it is connected to the adjacent electrode finger, so that part is not electrically charged. This prevents the material from floating, and therefore changes in characteristics can be reduced.

0012

【Example】

Figure 1 shows an enlarged view of the IDT electrode part of a surface acoustic wave device according to an embodiment of this invention. FIG. The parts that are the same as or correspond to the conventional example in FIG. The same reference numerals are used, and the differences from the conventional example will be mainly explained below.

[0013] In this embodiment, three (6) adjacent wires having the same length as described above are used. The tips of the electrode fingers 61 and 81 (this is an example of a split finger) These are connected by electrodes 10 and 12, respectively. Even if you do this, they will still have the same length. Since the electrode fingers 61 and 81 have the same potential, the characteristics are not affected.

[0014] Moreover, if this is done, the electrode fingers 61 and 81 at different potentials can be If a discharge occurs at a location such as The flow is divided into two directions: the base side of the twisted electrode finger 61 and the electrode 10 side connecting the tip thereof. Therefore, concentration of current can be avoided, and the electrode fingers 61 are less likely to break.

[0015] In addition, even if the electrode finger 61 breaks in the middle, the part beyond it will be damaged by the electrode 10. Since it is connected to the adjacent electrode finger 61, there is no possibility that that part will become electrically floating. Therefore, changes in characteristics can be reduced.

[0016] The same applies to the electrode finger 81 side.

[0017] In addition, the width of the electrodes 10 and 12 that connect the tips of the electrode fingers 61 and 81 is By making the widths of the electrodes that make up the pole fingers 61 and 81 smaller, acts like a fuse and breaks preferentially, so the electrode fingers 61 and 81 become disconnected. This can be more reliably prevented. In addition, if the electrodes 10 and 12 are disconnected, However, since both electrodes 10 and 12 are originally unnecessary in terms of characteristics, they do not affect the characteristics. stomach.

[0018] FIG. 2 shows the case of a solid finger in which each electrode finger 61, 81 is not divided into two parts. This is an example, and in this case, the width of the electrodes 10 and 12 is wider than the width of each electrode finger 61 and 81. As mentioned above, since the wire is made small, that part will be disconnected preferentially. .

[0019] Note that the above embodiments are all examples of 1/3 sampling, but this consideration The proposal is not limited to this, but it is possible to have multiple electrode fingers of the same length adjacent to each other. For example, in the case of 1/2 sampling (in this case, solid If you look at the fingers, they line up two by two) or there is zero excitation (zero impulse) (this In this case, if you look at the solid finger, it is usually the number of 0 impulses + 1 lined up), etc. can also be widely applied.

[0020]

[Effect of the idea]

As described above, according to this invention, the tips of multiple adjacent electrode fingers having the same length Since each part is connected with an electrode, even if a discharge occurs between electrode fingers with different potentials, it will not occur. Current can be divided into two directions, and as a result, electrode fingers are less likely to break. Ma In addition, even if an electrode finger breaks, the part beyond it will be connected to the adjacent electrode finger by the electrode. Since the part is connected to the can be made smaller.

[0021] In addition, the width of the electrode that connects the tips of the electrode fingers is If you make it smaller than the width, that part will act like a fuse and blow out preferentially. Since the electrode fingers are wired, disconnection of the electrode fingers can be more reliably prevented.

[Brief explanation of drawings]

FIG. 1 is an enlarged plan view partially showing an IDT electrode portion of a surface acoustic wave device according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view partially showing an IDT electrode portion of a surface acoustic wave device according to another embodiment of the invention.

FIG. 3 is a schematic perspective view showing an example of a surface acoustic wave device.

FIG. 4 is a schematic plan view showing an example of a crossed state of IDT electrodes.

FIG. 5 is an enlarged plan view partially showing an example of an IDT electrode portion of a conventional surface acoustic wave device.

[Explanation of symbols]

2 Surface wave substrate 4 IDT electrode 6,8 Comb tooth electrode 61,81 Electrode finger 10,12 electrode

Claims (2)

[Scope of utility model registration request] Claim 1: An IDT electrode consisting of a set of intersecting comb-shaped electrodes is formed on the surface of a surface wave substrate, and in this IDT electrode, a plurality of electrode fingers having the same length are arranged next to each other. A surface acoustic wave device characterized in that the tips of the plurality of adjacent electrode fingers having the same length are connected by electrodes. 2. The surface acoustic wave device according to claim 1, wherein the width of the electrode connecting the tips of the electrode fingers is smaller than the width of the electrodes constituting the electrode fingers.