JPS62263711A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To reduce the chip size without deteriorating the characteristic such as a waveform ripple of the frequency characteristic by prolonging a lead electrode to both upper/lower ends on a piezoelectric substrate and arranging the coating position of a reflection absorbing agent between lead electrodes so as to be overlapped with the lead electrode. CONSTITUTION:Input/output comb-line electrodes 12, 13 are arranged on the piezoelectric substrate 11, the lead electrodes 14, 15 for the wire bonding are prolonged from the comb-line electrodes 12, 13 to both the upper/ lower ends of the piezoelectric substrate 11 from the comb-line electrodes 12, 13, the end is formed as a key shape to ensure the area >=200mumX200mum. Further, in order to apply the reflection absorbing agent 16 suppressing the end face reflection is applied to be overlapped with the lead electrodes 14, 15 at the outside of the comb-line electrodes 12, 13 and a part is arranged between keyed-shapes of the lead electrodes 14, 15.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an elastic wave device used in television receivers, video tape recorders, etc. The configuration was as shown in Figures 3 and 4. Here, FIG. 3 is a plan view showing an example of a conventional acoustic wave device (large chip size), and FIG. 4 is a plan view showing another example of the conventional acoustic wave device (small chip size). In FIGS. 3 and 4, 1 is a piezoelectric substrate, 2.3 is a comb-shaped electrode for input and output provided on the substrate 1, and 4, 5 is a piezoelectric substrate.
6 is an extraction electrode provided in communication with each of the comb-shaped electrodes 2 and 3, and 6 is a reflection absorber for suppressing end face reflection. That is, a comb-shaped electrode 2.3 for input/output is arranged on the piezoelectric substrate 1, an extraction electrode 4.6 for wire bonding is provided on the comb-shaped electrode 2.3, and a reflection absorber is further applied to suppress end-face reflection. 6 was applied to the outside of the comb-shaped electrodes 2 and 3 so as not to overlap with the extraction electrodes 4 and 6.

At this time, it is desirable that the reflection absorbing agent 6 be applied as close as possible to the comb-shaped electrodes 2.3 and coated from end to end of the comb-shaped electrode crossing elongated holes. And the extraction electrode 4
, 6 have their ends on the reflective absorber side extending to the ends or near the ends of the comb-shaped electrodes 2 and 3, and the lead-out electrode ib for wire bonding has a minimum thickness of 200 μm or more, which is the minimum required for wire bonding. .

Here, in the conventional example shown in FIG. 3, the extraction electrodes 4 and 5 have the same length as the comb-shaped electrodes 2 and 3, so the width of the extraction electrodes 4 and 5 becomes large, and the piezoelectric substrate 1 The disadvantage is that the chip size becomes large. Also,
In the conventional example shown in FIG. 4, in order to reduce the chip size of the piezoelectric substrate 1, the width of the portions of the extraction electrodes 4 and 6 that overlap the comb-shaped electrodes 2 and 3 is made small, and the width of the extraction electrode for wire bonding is set to 200 μm. However, as shown in FIG. 5, when the chip size is small, it has the disadvantage that characteristics such as waveform ripple in the frequency characteristics deteriorate as shown by the characteristic curve.

Note that characteristic A in FIG. 5 is the frequency characteristic according to the conventional example shown in FIG.

Problems to be Solved by the Invention In such a conventional configuration, the width of the extraction electrode required for wire bonding is set at 200 μm or more, the area of the extraction electrode is secured at 200 μm x 200 μm or more, and a comb-shaped electrode can be formed. (Even if a reflective absorber is applied, the chip size will increase and the fourth
If the chip size is reduced in the configuration shown in the figure, the frequency characteristics will be adversely affected, resulting in problems in terms of characteristics and cost.

The present invention is intended to solve these problems, and aims to provide an inexpensive acoustic wave device that does not deteriorate characteristics such as waveform ripples in frequency characteristics, has a smaller chip size, and is less expensive.

Means for Solving the Problem In order to solve this problem, the present invention extends the lead electrode for wire bonding to both the upper and lower ends of the piezoelectric substrate, and changes the application position of the reflection absorber from the lead electrode. The structure is such that they are arranged between the extraction electrodes so that they overlap.

Effect: With this configuration, the chip size of the acoustic wave device can be reduced, and the reflection absorber can be applied close to the comb-shaped electrode, and the lead-out electrode for wire bonding can also be made smaller than 200μm x 2o○μm. This means that it is possible to secure an area of .

Embodiment FIG. 1 is a diagram showing an acoustic wave device according to an embodiment of the present invention. In FIG. 1, comb-shaped electrodes 12 and 13 for input and output are respectively arranged on a piezoelectric substrate 11, and wire bonding is performed. Connect the extraction electrodes 14 and 15 to each comb-shaped electrode 1.
2.13 to both upper and lower ends of the piezoelectric substrate 11, and the ends are hook-shaped and 200 μm x 200 μm.
Secure the above area. Further, a reflection absorbing agent 16 for suppressing end face reflection is arranged outside the comb-shaped electrodes 12.13, and is placed between the extraction electrodes 14.degree. The structure is such that a reflection absorbing agent 16 is applied. here,
A part of the reflection absorber 16 is connected to the extraction voltage q14,1.
It is applied so as to be placed between the hook-shaped parts (wire bonding parts) of the cs.

The second section is a diagram showing the frequency characteristics obtained by the acoustic wave device of the present invention. The chip size of the piezoelectric substrate is smaller than that of iYZ, and there is no characteristic deterioration such as waveform ripple in the frequency characteristic. The effect of the elastic wave device can also be seen from Figure 2.

Effects of the Invention As described above, according to the present invention, the width of the lead-out voltage for wire bonding can be made small in the comb-shaped electrode part, and the wire bonding part extending to the end of the piezoelectric substrate can have a width of 200 μm x 200 μm or more, thereby increasing the frequency. The chip size can be reduced without deterioration of characteristics such as waveform ripple, and an inexpensive acoustic wave device can be provided.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a plan view showing an elastic wave device according to an embodiment of the present invention, FIG. 2 is a diagram showing frequency characteristics of the elastic wave device according to the present invention, and FIG. 3 is a plan view showing a conventional elastic wave device. A plan view showing an example of a wave device (large chip size), and FIG. 4 shows another example of a conventional acoustic wave device (
FIG. 5 is a diagram showing the frequency characteristics of a conventional elastic wave device. . 11...Piezoelectric substrate, 12.13...
Comb-shaped electrode, 14.15... Extraction electrode, 16
...Reflection absorber. Name of agent: Patent attorney Toshio Nakao and 1 other person +/
--One piezoelectric F, substrate 12, /3-one comb-shaped electric wire/'i', 15-'51 length L/electrode 2nd figure → Shoulder pump double (1'I)-! Z no

Claims (1)

[Claims] Comb-shaped electrodes for input and output are arranged on a piezoelectric substrate, and extraction electrodes for wire bonding are provided extending from each comb-shaped electrode to both upper and lower ends of the piezoelectric substrate, and An acoustic wave device in which a reflection absorbing agent for suppressing end face reflection is coated between the extraction electrodes so as to overlap the extraction electrodes.