JP2001345673A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave device which can be readily manufactured in a small size like a surface acoustic wave element. SOLUTION: The surface acoustic wave device, which is formed by jointing two surface acoustic wave elements each having an exciting electrode on a piezoelectric substrate, while the piezoelectric substrate surfaces having the exciting electrodes formed thereon are opposed to each other, is characterized in that one of the piezoelectric substrates has the exciting electrode surface being larger than that of the other piezoelectric substrate, and a frame having an electrode formed thereon is disposed on an outer edge of one of the piezoelectric substrate to input and output a signal via the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device for a resonator and a frequency band filter incorporated in a mobile radio terminal device such as an automobile telephone and a portable telephone.

[0002]

2. Description of the Related Art Conventional surface acoustic waves (Surface Ac
An implementation of the oustic wave) device will be described in detail with reference to the drawings.

In recent years, in portable telephones, for example, 900 MHz
Dual-band compatible terminals have been used so that calls can be made in two bands, the z band and the 1.8 GHz band. In such a mobile phone, a plurality of surface acoustic wave devices are used so as to correspond to each band. Recently, in order to reduce the number of parts and reduce the weight and size of a mobile phone, a surface acoustic wave device in which functions of a plurality of such surface acoustic wave devices are integrated into one has been produced.

FIGS. 8 and 9 show examples. In FIG. 8, reference numerals 1 and 2 denote surface acoustic wave elements, which are formed by patterning a conductive film such as Al or an Al-Cu alloy on the surface of a piezoelectric substrate made of 36 ° Y-cut X-propagation lithium tantalate single crystal or the like. A pair of comb-shaped excitation electrodes 6 and 8 (Inter Digital Transduc
er, IDT electrodes) are arranged. This element is provided with an adhesive resin 14 in a casing 13 made of ceramic.
And connected to the input / output electrode 15 or the ground electrode 16 of the housing 13 and the respective lead electrodes 7 and 9 by wires 17. In order to provide weather resistance, the housing 13 and the lid 18 are sealed by seam welding or a sealing agent of solder or resin.

In FIG. 9, the side surfaces of the surface acoustic wave elements 1 and 2 are mounted on a housing 13, and the electrodes on the surface acoustic wave elements 1 and 2 and the electrode 19 on the housing 13 are connected by a conductor 4. Thereafter, the lid 18 is covered and sealed.

[0006] In any of the above cases, there is a problem that the surface acoustic wave device becomes large due to the plurality of piezoelectric elements. In particular, in the case of the surface acoustic wave in FIG. 8, there is a problem that a space for wire connection is required, and the surface acoustic wave device is further increased in size. Further, after mounting the two surface acoustic wave elements on the housing, it is necessary to cover and seal the lid, and there is a problem that the process becomes complicated.

An object of the present invention is to provide a surface acoustic wave device including a plurality of surface acoustic wave devices, which is as small as the surface acoustic wave device and easy to manufacture.

[0008]

In order to achieve the above object, a surface acoustic wave device according to the present invention comprises: two surface acoustic wave elements each having an excitation electrode formed on a piezoelectric substrate; A frame-like body formed by joining surfaces of the piezoelectric substrate so that the excitation electrode forming surface of one of the piezoelectric substrates is formed to have a larger area than the other, and having two surface acoustic wave elements and electrodes connected to an external circuit. Is disposed on the outer peripheral portion of one of the piezoelectric substrates, and the external circuit is connected to the external circuit through electrodes formed on the frame.
A signal is input and output between two surface acoustic wave elements.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a surface acoustic wave device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an end view of a surface acoustic wave device S1 according to the present invention. FIG. 2 shows a top view of the surface acoustic wave device S1. FIG. 1 is an end view taken along line AA ′ of FIG.

In the surface acoustic wave device S1, 1 and 2
Are surface acoustic wave elements each having an excitation electrode formed on a piezoelectric substrate. The excitation electrode 6 and extraction electrodes 7a and 7b are provided on the surface of the surface acoustic wave element 1, and the excitation electrode 8 and extraction electrodes 8 are provided on the surface of the surface acoustic wave element 2. Electrodes 9a and 9b are formed. The lead electrodes 7a and 9a, 7b and 9b are connected by conductors 4a and 4b. The conductors 4a and 4b are formed of Au bumps, solder bumps, or conductive resin. The frame 3 is disposed outside the surface acoustic wave element 2, and a lead electrode 7 is provided.
The electrodes a and 7b are connected to the electrodes 10 formed on the surface of the frame 3 via the conductors 4c and 4d.

When the surface acoustic wave device S1 is mounted on an external circuit, the electrode 10 on the surface of the frame 3 is connected to the external circuit.

The space between the surface acoustic wave elements 1 and 2 and the frame 3 is filled with a sealing resin 5, and the excitation electrodes 6, 8 and the extraction electrodes 7a, 7b, 9a, 9b are sealed. The weather resistance of the device S1 is obtained.

FIG. 3 is a top view of the surface acoustic wave device 1. FIG.
After the surface acoustic wave element 1 forms an Al—Cu alloy thin film on a piezoelectric substrate, the excitation electrode 6, the extraction electrode 7a,
7b is formed and finally diced. Here, in the figure, 11 indicates the position where the conductor 4 is arranged, and 11
The conductors arranged at positions a, 11b, 11c, and 11d are connected to the surface acoustic wave element 2, and 11e, 11f, 11g, and 11h.
Is connected to the frame 3.

FIG. 4 shows a top view of the surface acoustic wave device 2. FIG.
After forming the excitation electrode 8 and the extraction electrodes 9a and 9b in the same process as the surface acoustic wave element 1,
Created by dicing. Here, in the figure, 12 indicates a place where the conductor 4 is arranged, and 12a, 12b, 12c, 1
2d are both connected to the surface acoustic wave element 1.

The surface acoustic wave device 2 produced as described above
Is connected to the surface acoustic wave element 1 via the conductor 4, the frame-shaped body is fitted on the outer periphery thereof, and then the sealing resin is filled to complete the assembly of the surface acoustic wave device S1. Here, the dicing of the surface acoustic wave element 1 is performed after the above assembly. That is, the surface acoustic wave element 1 is diced at the end of the process, and the surface acoustic wave device S1 is completed.

Thus, according to the present invention, the excitation electrode forming surface of one piezoelectric substrate is formed in a larger area than the other, and
Since the frame formed with the two surface acoustic wave elements and the electrodes connected to the external circuit is disposed on the outer peripheral portion of one of the piezoelectric substrates, the external circuit and the two elastic members are formed via the electrodes formed on the frame. Signals can be input and output to and from the surface acoustic wave element.

After the surface acoustic wave element 2 is connected via the conductor 4 to the piezoelectric substrate on which the surface acoustic wave element 1 is formed, even if the positioning accuracy of the frame is not high, the surface acoustic wave The position is reliably determined by aligning the side surface with the element 2, and the assembling process can be extremely simplified.

Further, since a housing for sealing and a support substrate for connecting the electrodes of the surface acoustic wave element to an external circuit are not required, the surface acoustic wave device has a small thickness and a small mounting area. A small and very small surface acoustic wave device can be obtained.

When the surface acoustic wave element is formed, a protective film such as Si, SiO2, SiN or the like may be formed on the excitation electrode. Also, a protective film against physical impact such as polyimide resin on the back surface of the substrate, or Al, Al-Cu, C
A metal film as an electromagnetic shield for a surface acoustic wave device such as r / Au may be formed.

Bonding by Au bumps or solder bumps is performed by thermocompression bonding, and bonding by a conductive resin is performed by thermocompression bonding or room temperature compression bonding. As the conductive resin, a mixture of a conductive filler such as metal and carbon in a polymer resin or a paste as a gel suspension is used.From the viewpoint of preventing short-circuit between terminals, anisotropic conductive resin is used. desirable.

The sealing resin 5 may be made of a thermosetting epoxy resin, silicone resin, phenol resin, or the like.
Polyimide resin, low melting point glass, thermoplastic polyphenylene sulfide, and the like are used, and epoxy resin is particularly preferable in terms of adhesiveness, low moisture absorption, electrical insulation, mechanical strength, chemical resistance, and heat resistance. In filling the sealing resin, it is necessary to control the discharge amount of the resin by using an auto dispenser or the like so that the sealing resin does not flow into the vibration space immediately above the IDT electrode. Further, at the time of sealing, it is desirable to seal in a N2 or Ar atmosphere so that high-humidity air is not sealed in the vibration space.

FIG. 6 is an end view of a surface acoustic wave device S2 according to another embodiment of the present invention. FIG. 7 shows a top view of the surface acoustic wave device S2. FIG. 6 is an end view taken along line AA ′ of FIG.

In the surface acoustic wave device S2, the electric connection between the frame 3 and the surface acoustic wave element 1 is performed by electrically connecting the electrode 10 formed on the side surface of the frame 3 and the electrode of the surface acoustic wave element 1. This is performed by joining with the bodies 4a and 4b. In this method, there is no conductor between the frame 3 and the surface acoustic wave element 1. Therefore, the frame 3 and the surface acoustic wave element 1 can be contacted with almost no gap. For this reason, it is suppressed that the sealing resin 5 goes around into the vibration space between the excitation electrodes 6 and 8, and
The sealing step can be performed stably. Further, in this method, sealing between the frame 3 and the surface acoustic wave element 2 is necessary, but since there is almost no gap between the frame 3 and the surface acoustic wave element 2, the excitation electrodes 6 and 8 It is suppressed that the sealing resin 5 goes into the vibration space between them.

As the piezoelectric substrate, lithium tantalate single crystal, lithium niobate single crystal, quartz, lithium tetraborate single crystal, langasite single crystal, potassium niobate single crystal, and gallium arsenide can be mainly used.

The excitation electrodes 6 and 8 are mainly made of aluminum,
Aluminum / copper alloy, aluminum / titanium alloy, aluminum / silicon alloy, gold, silver, silver / palladium alloy can be mainly applied.If a base material is required to improve the adhesion of the electrode and reduce the electric resistance, Chromium, titanium and copper are mainly applicable.

When a conductive resin is used for the conductor 4, a thermosetting resin (epoxy type, silicone type, phenol type, polyimide type, polyurethane type, etc.), a thermoplastic resin (polyphenylene sulfide, etc.), an ultraviolet curable resin Alternatively, a material in which a metal filler is mixed at an arbitrary ratio in low-melting glass or the like can be mainly applied.

In the above-described embodiment, the configuration of the resonator ladder type filter is used as the excitation electrode. However, the excitation electrode is formed by a resonator lattice type filter, a dual mode resonator type filter, a multi-IDT electrode type filter, or a combination thereof. It does not matter.

Further, in the above-described embodiment, a configuration diagram is shown in which the extraction electrodes of the two surface acoustic wave elements are connected to each other and connected to the surface electrode of the frame 3 as a common electrode. The electrode on the surface of the frame 3 connected to the surface acoustic wave element 2 is connected to the electrode on the surface of the frame 3 connected to the surface acoustic wave element 1 via a routing electrode provided on the surface of the surface acoustic wave element 1. It may be provided separately.

The base material of the frame 3 is preferably an insulating material, and ceramics, epoxy, silicone, phenol, polyimide, polyurethane resin, and glass can be mainly used. Also, the thickness of the frame is preferably about the same as the thickness of the surface acoustic wave element in the same layer.

In the above embodiment, the surface acoustic wave element 2 is connected to the surface acoustic wave element 1 by the conductor 4. However, the surface acoustic wave element 2 is connected to the electrode 10 on the surface of the frame 3, and this electrode is It may be connected to the surface acoustic wave device 1 or an external circuit via the same.

To reliably prevent the sealing resin 5 from entering the vibration space, a high-viscosity resin or the like is dropped around the surface acoustic wave element 2 to seal the gap between the surface acoustic wave elements 1 and 2. After that, a sealing resin 5 for obtaining weather resistance may be filled.

It should be noted that the present invention is not limited to the above embodiment, but can be applied not only to a SAW filter but also to a SAW resonator and a SAW duplexer. No changes can be made.

[0034]

Example: 0.35 mm thick 3 inch 42 ° Y-cut X
An Al-Cu alloy was formed as a film having a thickness of 2,000 mm on the propagating lithium tantalate single crystal piezoelectric substrate by sputtering as an electrode film. A positive resist was applied thereon by spin coating at a thickness of 1 μm. Thereafter, exposure and development were performed to pattern the resist, the excitation electrode and the lead electrode were etched by dry etching, and the resist was removed by ashing, thereby completing the electrode patterning.

After that, the SiO 2 film is formed by CVD method for 20 minutes.
A 0 ° film is formed, a positive resist is applied in a thickness of 1 μm by a spin coating method, exposure and development are performed, patterning of the resist is performed, electrodes are etched by a dry etching method, the resist is removed by ashing, and excitation is performed. A protective film was patterned on the electrode.

The 3-inch piezoelectric substrate is diced using a dicing saw, and a 2.4 mm square surface acoustic wave element 1 is diced.
Was completed.

Next, 3 inches 42 ° of 0.35 mm thickness
On the Y-cut X-propagation lithium tantalate single crystal piezoelectric substrate, an Al-Cu alloy is used as an electrode film with a thickness of 400 by sputtering.
A film was formed at 0 °, and a surface acoustic wave device 2 of 1.0 mm square was completed in the same manner as described above.

The frame 3 is 2.4 mm square and 0.3 m thick.
A 0.3 mm-wide electrode was formed by electroless plating Au and Ni with a total thickness of 1 μm on a frame-shaped ceramic substrate having a height of 0.35 mm.

The above elements were mounted as follows using an automounter.

A conductive resin 4 having a diameter of 0.1 mm is attached to each of the four extraction electrodes of the surface acoustic wave elements 1 and 2 using a micro syringe, and the surface acoustic wave element 2 is mounted by a mounter.
Was placed on the surface acoustic wave element 1 with a gap of 0.1 mm, and was brought into contact with a hot plate at a plate temperature of 100 ° C. for 30 seconds to solidify the conductive resin 4. Next, a conductive resin 4 having a diameter of 0.1 mm was attached to four extraction electrodes of the surface acoustic wave element 1 using a micro syringe, and the frame 3 was fixed by crimping. The nozzle of the micro syringe was moved along the inner wall of the frame at 1.0 mm / sec while discharging the sealing resin 5 at a rate of 0.2 μL / sec with the micro syringe to fill the sealing resin 5. Sealing was performed in a nitrogen atmosphere.

By the above steps, the size is 2.4 mm in width,
An ultra-small surface acoustic wave device having a depth of 2.4 mm and a height of 0.7 mm was completed.

[0042]

As described above in detail, according to the surface acoustic wave device of the present invention, a housing for sealing as in the prior art is not required, and the electrodes of the surface acoustic wave element and the external circuit are not required. Since a supporting substrate for connecting the surface acoustic wave device is not required, the thickness of the entire surface acoustic wave device can be reduced, and the surface acoustic wave device having a small mounting area, a very small size, and an excellent height reduction is provided. be able to.

Further, since the number of members can be reduced as much as possible, it is possible to provide an excellent surface acoustic wave device which can be completed with a low material cost and simple assembly.

[Brief description of the drawings]

FIG. 1 is an end view of an embodiment of a surface acoustic wave device according to the present invention.

FIG. 2 is a top view of one embodiment of the surface acoustic wave device according to the present invention.

FIG. 3 is a top view of the surface acoustic wave device 1 of the present invention.

FIG. 4 is a top view of the surface acoustic wave device 2 of the present invention.

FIG. 5 is a top view of a frame according to the present invention.

FIG. 6 is an end view of one embodiment of a surface acoustic wave device according to the present invention.

FIG. 7 is a top view of another embodiment of the surface acoustic wave device according to the present invention.

FIG. 8 is an end view of a conventional surface acoustic wave device.

FIG. 9 is an end view of another conventional surface acoustic wave device.

[Explanation of symbols]

1: Surface acoustic wave element 2: Surface acoustic wave element 3: Frame-shaped body 4: Conductor 5: Sealing resin 6: Excitation electrode on surface acoustic wave element 1 7a, 7b: Extraction electrode on surface acoustic wave element 1 8: Excitation electrodes on surface acoustic wave element 2 9a, 9b: Extraction electrodes on surface acoustic wave element 2 10: Electrodes on frame surface 11a, 11b, 11c, 11d, 11e, 11f, 1
1g, 11h: Position where conductor is arranged in surface acoustic wave element 1 12a, 12b, 12c, 12d: Position where conductor is arranged in surface acoustic wave element 2 13: Housing 14: Adhesive resin 15: Input / output Electrode 16: Ground electrode 17: Wire 18: Lid 19: Electrode in housing

Claims (1)

[Claims] 1. A surface acoustic wave device comprising two surface acoustic wave elements each having an excitation electrode formed on a piezoelectric substrate and joined to each other with the excitation electrode forming surfaces of the piezoelectric substrate facing each other. The excitation electrode forming surface of the piezoelectric substrate is formed to have a larger area than the other, and a frame-like body formed with the two surface acoustic wave elements and the electrodes connected to the external circuit is arranged on the outer peripheral portion of the one piezoelectric substrate. A surface acoustic wave device wherein signals are input and output between the external circuit and the two surface acoustic wave elements via electrodes formed on the frame-shaped body. .