JPS587911A - Surface acoustic wave resonator device - Google Patents

Abstract

PURPOSE:To obtain an inexpensive, small-sized and highly reliable surface acoustic wave resonator device by connecting an electrode leading wire so as to constitute a part of a grating electrode. CONSTITUTION:Out of a pair of electrode leading wires 223, 224 connecting an exciting electrode 22 and terminals 221, 222 attached along a side of a piezoelectric plate 21, at least one lead wire 223 is separated by lambda/4 (lambda is resonance wavelength at the resonance frequency) respectively from repellers 242, 243 between which the lead wire 223, a repeller 241, is put so that the lead wire 223 acts as one repeller 241 in a grating electrodes 24. In this way, the repeller can be increased on the piezoelectric plate 21 without the consideration of a space for the lead wire 223. Thus the inexpensive and highly reliable surface acoustic wave resonator device can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface acoustic wave resonator device, and more particularly, the present invention relates to a surface acoustic wave resonator device in which at least one surface acoustic wave resonator is formed on a piezoelectric substrate. The present invention relates to an electrode lead that can be connected to terminals arranged in a row along one side of a substrate without affecting the characteristics of a surface acoustic wave resonator.

For example, a VTR uses a structure in which it receives television radio waves sent in the UHF and VHF ranges, and when it is necessary to record or record according to the viewer's preference, it plays back the recorded signal on an empty channel of the television device. ing. For this reason, the RF converter must oscillate the same carrier wave as the carrier wave of the empty channel. Since these free channels vary depending on the region, an RF converter is usually configured to be able to use two channels: a first channel (91.25 MHZ) and a second channel (97.25 MHZ).

In recent years, with the development of surface acoustic wave resonators that can directly oscillate high frequencies for television broadcast channels, etc., surface acoustic wave resonators are being used as the oscillation element of RF converters instead of crystal resonators that require a multiplier circuit. The circuit configuration of the RF converter is simplified.

Next, main parts of an example of a surface acoustic wave resonator device will be explained with reference to FIGS. 1 and 2.

That is, on a piezoelectric substrate (1) made of LiTaO3, LINbO3, crystal, ceramics, etc., there is an excitation electrode (2) made of an interdigital electrode, and a pair of grading electrodes provided at a predetermined interval on both sides of this excitation electrode (2). (3), (4) and the terminal (21) of the excitation electrode (2)
The surface acoustic wave resonator formed in (22) is placed on a round stem (TO-8) (6) in which lead wires (51) and (52) are implanted through an insulating member through an adhesive layer. After connecting the terminals (21) and (22) to the lead wires (51 and 52) using bonding wires, the shell (7)
The surface acoustic wave resonator device was completed by airtight sealing.

However, although the device using such a round stem (6) has the advantage that the terminals (21) and (22) can be directly formed on both sides of the piezoelectric substrate (1), compared to a surface acoustic wave resonator, the round stem (6) The shape of the stem (6) and shell (7) is large, and there is a drawback that a large space is required when disposing them on a circuit board together with other parts.

In order to eliminate this drawback, recently a rectangular stem shell is used, and a line of lead wires are installed through the stem, and these lead wires are bent to reduce the space of the surface acoustic wave resonator device. Structures like this are being touted.

Next, an example of such a surface acoustic wave resonator device will be explained with reference to FIGS. 3 and 4.

That is, as in the previous example, on the piezoelectric substrate (11) there is an excitation electrode (12) made of an interdigital electrode, and a pair of grading electrodes (13) (14) provided at a predetermined interval on both sides of this excitation electrode (12). ), piezoelectric substrate (11)
Surface acoustic wave resonance with terminals (121) (122) provided along one side and a pair of electrode lead leads (123) (124) connecting the excitation electrode (12) and the terminals (121) (122). The child is placed and fixed on a rectangular stem (16) made of metal through which lead wires (151, 152) are implanted through an insulating member (19) via an adhesive layer (18), and the terminal ( 121 and 122 are connected to the lead wires (151 and 152) by bonding wires (20), and then hermetically sealed by the shell (17) to complete the surface acoustic wave resonator device.

However, in a surface acoustic wave resonator device having such a structure, since the terminals (121) (122) must be provided along one side of the piezoelectric substrate (11), the piezoelectric wires of the electrode lead leads (123) (124) The area occupied on the substrate (11) increases, and the long and/or short sides of the piezoelectric substrate (11) are lengthened in proportion to the area, and the cost of the surface acoustic wave resonator device also increases. It will become. As a countermeasure for this, grading electrodes (13) (14)
) There is an idea to reduce the number of reflective electrodes from the usual 200, but the relationship between the number of reflective electrodes and the loss is as shown in the curve (
Because of the relationship shown in 8), the electrode lead (
Reducing the number of reflective electrodes for 123) (124) has the disadvantage of directly leading to loss of the surface acoustic wave resonator device, and also reduces the number of electrode lead leads (123) (124).
4) It is possible to reduce the cross-sectional area and make the wire thinner, but
This also had the drawback of leading to disconnection of the electrode lead leads (123) (124).

These drawbacks become even more problematic when a plurality of surface acoustic wave resonators are provided on a single piezoelectric substrate.

The present invention has been made in view of the above-mentioned conventional drawbacks, and even if the electrode lead is formed with a normal cross-sectional area, the loss of the surface acoustic wave resonator device does not increase, and the piezoelectric substrate is made larger. There is no cost increase due to
The object of the present invention is to provide a surface acoustic wave resonator device that is inexpensive, compact, and has excellent characteristics.

Next, a first embodiment of the surface acoustic wave resonator device of the present invention will be described with reference to FIGS. 6 to 8.

That is, on a piezoelectric substrate (21) made of LiTaO3, LiNbO3, crystal, ceramics, etc., there is an excitation electrode (22) made of an interdigital electrode;
2) a pair of grading electrodes (23) (24) provided at a predetermined interval on both sides of the piezoelectric substrate (21), terminals (221) (222) provided along one side of the piezoelectric substrate (21), and an excitation electrode (23). A pair of electrode leads (223) (224) connecting the terminals (221) and (222) are formed, and the surface acoustic wave resonator is almost as shown in Figures 3 and 4. It is almost the same as the grading electrode (21), but a part of the electrode lead (224) is
) from the reflective electrodes (242) and (243) that sandwich this reflective electrode (241) at a distance of 4/4 (where the input is the resonant wavelength at the resonant frequency of the resonator). They are arranged to have a width of /4.

According to the experimental results, the position of the reflective electrode (241), which also serves as a part of the electrode lead (224), is one point counting from the excitation electrode (22) side, as shown by the curve (9) in Figure 8.
By using the 50th reflective electrode or more, the loss will be within the specified range.Also, by using a part of the electrode lead (224) as a reflective electrode (241), the lead lead (224) can be placed on the piezoelectric substrate (21). It is possible to sufficiently increase the number of reflective electrodes without considering the space required.

Next, the lead wires (251) and (252) are connected to the insulating member (252) through the adhesive layer (28).
The terminals (221) (222) are connected to the lead wires (251) (251) (22) using the bonding wires (30).
52) and then hermetically sealed with the shell (27) to complete the surface acoustic wave resonator device.

By adopting such a structure, it becomes possible to form the grading electrode (24) without considering the space for the electrode lead (224) as described above, so that a predetermined number of reflective electrodes are formed and the elastic surface The properties as a wave resonator device, especially the loss, are reduced, and the piezoelectric substrate (21
) becomes small, and as a result, it becomes possible to obtain an inexpensive surface acoustic wave resonator device with good characteristics.

Next, the main part of a modification of the first embodiment will be explained with reference to FIG. In the figure, the same reference numerals as in the first embodiment indicate the same parts.

That is, in this example, the electrode lead (223) is made wider to ensure safety against disconnection, and in this case, a part of the electrode lead (223) is connected to a plurality of grading electrodes (24). In the example, there are two reflecting electrodes (two in the example).
Reflecting electrodes (2411) (2412)
) (2412), the width of the reflection electrodes (2412) is 1/4, the interval is 1/4, and the adjacent reflective electrodes (242) and (243) are arranged to have a width of 1/4.

Next, a surface acoustic wave resonator adapted to the second embodiment of the surface acoustic wave resonator device of the present invention will be explained with reference to FIG. In the figure, the same reference numerals as those in the first embodiment indicate the same parts, and no particular explanation will be given.

That is, one terminal (222) of the terminals (221) and (222) of the excitation electrode (22) is directly connected to the excitation electrode (22) without going through the electrode lead, and the other terminal (221) is Although connected via an electrode lead (223), in this surface acoustic wave resonator,
The number of reflective electrodes of the grading electrode (24) is smaller than the number of reflective electrodes of the grading electrode (24), that is, it is asymmetrical, and the portion of the grading electrode (24) with fewer reflective electrodes is also used as a part of the electrode extraction lead (223). I try to let them do it.

That is, a part of the electrode lead (223) is parallel to the grading electrode (24), and a plurality of (two in the figure) reflective electrodes (2441) (2442) are connected to the grading electrode (24) depending on its width.
This reflective electrode (2441) (244
2) The width of... is set to /4, the interval is set to /4, and the last reflective electrode (24) of the cladding electrode (24)
n) Set the interval between (2441) to /4 or to /4
It is characterized by being in the positive digit of . , By having such a structure, the electrode lead (2
Reflective electrode (2441) provided in a part of (23)
42), the number of reflective electrodes of the grading electrodes (23) and (24) becomes symmetrical with respect to the excitation electrode (22), and in particular, the space for the electrode lead (223) is not provided on the piezoelectric substrate (21). (221) (222)
There is an advantage that it is possible to provide the piezoelectric substrate (21) near one side of the piezoelectric substrate (21).

Next, a surface acoustic wave resonator adapted to the third embodiment of the surface acoustic wave resonator device of the present invention will be explained with reference to FIG. In the figure, the same parts as in the first embodiment are denoted by the same reference numerals.
In this example, two surface acoustic wave resonators are formed on the same piezoelectric substrate, so one will be described with (a) and the other with (b), and the grading electrode is (X ) is indicated.

That is, in this example, the excitation electrode (21) is placed on the piezoelectric substrate (21).
22a) and grading electrodes (23a) (24a), and an excitation electrode (22b).
) and a second surface acoustic wave resonator consisting of grading electrodes (23b) (24b), and V
It has a structure suitable for two-channel applications such as TR.

In such two surface acoustic wave resonators, one of the excitation electrodes (22a) of the first surface acoustic wave resonator labeled (a) is connected to the terminal (22a) via the electrode lead (233a).
221a), and one of the excitation electrodes (22b) of the second surface acoustic wave resonator labeled (b) is connected to the terminal (222a) via the electrode lead (224a). The other of the excitation electrodes (22a) (22b) is connected and then connected to the electrode lead (224a/223b)
The terminals (222a, 221b) are connected to the terminals (222a, 221b) through the terminals, which is almost the same as the conventional one, but in this example, the electrode lead (223a) has the same structure as the first example.
That is, the reflective electrode of the grading electrode (24a) is used to connect to the terminal (221a), and the electrode lead (224a) is connected to the terminal (221a).
a and 223b) have the same structure as the second embodiment, that is, they are added to the reflective electrode of the grading electrode (24b). By adopting such a structure, the length of the piezoelectric substrate (21) can be determined according to the low-frequency surface acoustic wave resonator, and there is no need to consider the space for the electrode lead. As a surface wave resonator device, it is also possible to obtain low cost, small size, and high reliability.

By providing the electrode lead as a part of the grading electrode as described above, it is inexpensive, small, and
Since a highly reliable surface acoustic wave resonator device can be obtained, the industrial value of the present invention is extremely large.

[Brief explanation of drawings]

1 and 2 are diagrams showing an example of a conventional surface acoustic wave resonator device, and FIG. 1 is a plan view of the surface acoustic wave resonator;
FIG. 2 is a partially cutaway perspective view, FIGS. 3 and 4 are views showing other examples of conventional surface acoustic wave resonator devices, FIG. 3 is a partially cutaway perspective view, and FIG. 4 is a partially cutaway perspective view. Fig. 3 is a cross-sectional view taken along the X1 and X1 lines and viewed in the direction of the arrow, Fig. 5 is a curve diagram showing the relationship between the number of reflective electrodes and loss, and Figs. 6 to 8 show the elastic properties of the present invention. FIG. 6 is a partially cutaway perspective view, FIG. 7 is an explanatory diagram of the main part, and FIG.
The figure is a curve diagram showing the change in loss depending on the position of the electrode lead, FIG. 9 is an explanatory diagram of the main part showing a modification of the first embodiment, and FIG. 10 is adapted to the second embodiment of the present invention. A plan view of a surface acoustic wave resonator. FIG. 11 is a plan view of a surface acoustic wave resonator adapted to a third embodiment of the present invention. 22a, 22b...excitation electrodes 3, 4
, 13, 14, 23, 24, 23a, 23b, 24a,
24b...Grading electrodes 21, 22, 121, 122, 222, 221a, 22
2b, 222a/222b...terminals 123, 124
, 223, 224, 233a, 224a, 224a・2
23b... Electrode extraction leads 241, 242, 243, 2441, 2442... Reflective electrode agent Patent attorney Kazuo Inoue

Claims (3)

[Claims] (1) In a surface acoustic wave resonator device in which at least one surface acoustic wave resonator is formed on a piezoelectric substrate and includes an excitation electrode and a pair of grading electrodes provided on both sides of the excitation electrode, the excitation electrode A surface acoustic wave resonator device characterized in that at least one of a pair of electrode lead leads connecting a terminal on the piezoelectric substrate and a terminal on the piezoelectric substrate is provided so as to constitute a part of the grading electrode. (2) The surface acoustic wave resonator device according to claim 1, wherein the means provided so as to constitute a part of the surface acoustic wave resonator device is characterized in that at least one reflective electrode among the grading electrodes is used. . (3) The means provided so as to form part of the excitation electrode reduces the number of reflective electrodes on at least one of the grading electrodes provided on both sides of the excitation electrode, and the endmost reflective electrode of the grading electrode is placed in the reduced portion. A patent claim characterized in that at least one electrode is used that has approximately the same shape and the same spacing as the grading electrode and is spaced apart from 1/4 or a positive multiple of 1/4 of the resonant wavelength. The surface acoustic wave resonator device according to item 1.