JPH1197971A - Surface acoustic wave element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface acoustic wave element in which a surrounding body is difficult to be detached from a piezoelectric substrate by providing a surrounding body for covering a comb-shaped electrode, and making one part of input and output electrodes be exposed on a piezoelectric substrate, and obtaining the angular part of the surrounding body as an obtuse angle. SOLUTION: A reflector and electrodes such as a comb-shaped electrode and input and output electrodes 100 are provided on the surface of a piezoelectric substrate 1 such as a lithium tantalate by using metal such as aluminum. A surrounding wall and a cover body 17 are formed so that one part of the electrodes can be surrounded. The angular parts of the surrounding body formed so that one part of the input and output electrodes 100 can be exposed are obtained as obtuse angles by using the surrounding wall and the cover body 17. Thus, any stress on the angular parts can be dispersed, and the surrounding body can be prevented from being peeled from the piezoelectric substrate 1 due to water pressure at the time of dicing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface acoustic wave device such as a filter and an oscillator.

[0002]

2. Description of the Related Art Conventionally, in order to obtain a large number of surface acoustic wave elements on a large piezoelectric substrate, a plurality of sets of comb electrodes are formed, and then the comb electrodes forming the individual surface acoustic wave elements are sealed. Next, as shown in FIG. 6, a rectangular enclosure 30 is provided so as to cover the comb-shaped electrodes on the piezoelectric substrate 1 and to expose the output electrodes 100, and then dicing the individual surface acoustic waves. It was separated into elements.

[0003]

According to this configuration, there is a problem that the water sprayed at the time of dicing hits the connecting portion between the envelope and the piezoelectric substrate, and the envelope comes off the piezoelectric substrate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface acoustic wave device in which an enclosure is hardly detached from a piezoelectric substrate.

[0005]

In order to achieve this object, a surface acoustic wave device according to the present invention comprises a piezoelectric substrate, at least one set of comb-shaped electrodes provided on the piezoelectric substrate, and a connection to the comb-shaped electrodes. At least one pair of input and output electrodes, and an enclosure that covers the comb-shaped electrode on the substrate and that is provided so that a part of the input and output electrodes is exposed, at least one corner of the enclosure Part has an obtuse angle,
In manufacturing, stress on the corners of the enclosure due to impact such as water pressure is dispersed, and the enclosure can be prevented from peeling off from the piezoelectric substrate. The dispersion of the stress applied to the corners of the surrounding body increases as the angle of the corners increases.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a piezoelectric substrate, at least one set of comb electrodes provided on the piezoelectric substrate, and at least one set of input electrodes connected to the comb electrodes. An output electrode, and an enclosure that covers the comb-shaped electrode on the substrate and is provided so that a part of the input and output electrodes is exposed, and at least one corner of the enclosure has an obtuse angle. This is a surface acoustic wave element that can prevent the enclosure from peeling off from the piezoelectric substrate due to impact such as water pressure during manufacturing.

According to a second aspect of the present invention, there is provided the surface acoustic wave device according to the first aspect, wherein the enclosure is formed using a photosensitive resin, and the enclosure having a desired shape can be easily formed. Can be.

According to a third aspect of the present invention, there is provided the surface acoustic wave device according to the first aspect, wherein the envelope on the input and output electrodes has a concave portion. The contact area between the body and the piezoelectric substrate can be increased.

According to a fourth aspect of the present invention, there is provided the surface acoustic wave device according to the first aspect, wherein at least one coupling layer is provided between the surrounding body and the piezoelectric substrate. The envelope can be prevented from peeling off.

According to a fifth aspect of the present invention, there is provided the surface acoustic wave device according to the fourth aspect, wherein the coupling layer is a monolayer, and the adhesion between the piezoelectric substrate and the enclosure is improved.

According to a sixth aspect of the present invention, there is provided the surface acoustic wave device according to the fourth aspect, wherein the coupling layer is formed using a silane compound, and the adhesion between the piezoelectric substrate and the enclosure is improved. .

According to a seventh aspect of the present invention, there is provided the surface acoustic wave device according to the fifth aspect, wherein the surface area of the coupling layer is larger than the area of the surrounding body in contact with the piezoelectric substrate. Can be prevented from deteriorating due to misalignment.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a top view of a surface acoustic wave device according to the present embodiment, FIG. 2 is a cross-sectional view of a surface acoustic wave device using the surface acoustic wave device of FIG. 1, and FIGS. FIG. 4 is an explanatory diagram of a manufacturing process of the surface acoustic wave device shown in FIG.

In FIG. 3, first, a reflector, a comb-shaped electrode, and electrodes 2 such as input and output electrodes are provided on the surface of a piezoelectric substrate 1 such as quartz, lithium niobate, lithium tantalate or the like by using a metal such as aluminum. Next, a coupling agent formed using a silane-based compound is dropped on the piezoelectric substrate 1, and a monolayer coupling layer 3 is formed on the entire surface of the piezoelectric substrate 1 by a spin coater. Here, it is important that the thickness of the coupling layer 3 be smaller than the thickness of the electrode 2. This is because if the coupling layer 3 is thick, it does not become a monomolecular layer, and the adhesion between the piezoelectric substrate 1 and the surrounding wall 10 is weakened. Subsequently, the first protective film 5 of the first sheet A in which the photosensitive resin film 4 is sandwiched between the first protective film 5 and the second protective film 6 is peeled off. Next, the photosensitive resin film 4 and the piezoelectric substrate 1 and the electrode 2 and the coupling layer 3 provided thereon are heated to 60 to 120 ° C. and pressurized using the roller 7 to be bonded. The first affixed to the piezoelectric substrate 1
A photomask 8 for the surrounding wall is overlaid on the second protective film 6 of the sheet A, and ultraviolet light 9 is irradiated. The portion of the photosensitive resin film 4 which has received the ultraviolet light is stabilized by polymerization and crosslinking reactions. After the second protective film 6 is peeled off, development is performed to form the surrounding wall 10 so as to surround at least a part of the electrode 2. It is necessary to use a chemical solution having a composition that does not corrode the electrode material such as aluminum as a developer used for development. As a developer which does not corrode the aluminum electrode, water, diethylene glycol monobutyl ether and borax each 800 ml,
There is a mixture of 200 ml and 8 g. On the other hand, as shown in FIG.
A spacer 12 made of a material such as polyethylene or Teflon, which has a convex portion adapted to the inner diameter and thickness of the first sheet, and which does not easily adhere to the photosensitive film, is fitted to the second sheet having the same configuration as the first sheet A. First protective film 1 of sheet B
4 is removed and the photosensitive resin film 13 is heated to 60 to 120 ° C.
Paste in. A photomask 16 for a lid is overlaid on the second protective film 15 of the second sheet B attached to the ring-shaped frame 11 and irradiated with ultraviolet light 9. After the ultraviolet irradiation, the spacer 12 is removed, and the second protective film 1 of the second sheet B is removed.
5 is used as a supporting member for development to form the lid 17. Thereafter, the surrounding wall 1 formed on the piezoelectric substrate 1 as shown in FIG.
After the positions of the cover 17 and the cover 17 formed on the second protective film 15 are aligned, the cover 17 is heated to 60 to 120 ° C. and joined by pressing. After the joining, ultraviolet rays 9 are irradiated, and the surrounding wall 10
And after the lid 17 is cured, the second sheet B
Is separated. The element thus formed is diced and separated into individual surface acoustic wave elements as shown in FIG. Obtain a surface acoustic wave device.

The points of the present invention will be described below. (1) As shown in FIG. 1, by making the corners of the enclosure formed using the enclosure wall 10 and the lid 17 obtuse, the stress applied to the corners is dispersed and the water pressure at the time of dicing causes It is possible to prevent the enclosure from peeling off from the piezoelectric substrate 1. (2) As shown in FIG. 1, by providing a concave portion on the input and output electrodes 100 of the enclosing body, the contact area between the enclosing wall 10 and the piezoelectric substrate 1 can be increased without increasing the size of the surface acoustic wave element. Can be increased. (3) By using a material that crosslinks an inorganic component and an organic component, such as a silane-based compound, as the material of the coupling layer 3, the piezoelectric substrate 1 made of an inorganic material and the surrounding wall 10 made of an organic material are used. And the adhesion to the substrate can be further improved. (4) If the coupling layer 3 has a plurality of layers, the piezoelectric substrate 1 and the surrounding wall 10 are easily separated from each other due to a decrease in the adhesion between the coupling layers 3. Therefore, the coupling layer 3 is formed as a single layer. Is preferred. (5) By forming the coupling layer 3 on the entire surface of the piezoelectric substrate 1, it is possible to prevent a decrease in adhesion between the surrounding wall 10 and the piezoelectric substrate 1 due to a displacement of the surrounding wall 10.

[0016]

As described above, according to the present invention, it is possible to prevent the envelope from coming off the piezoelectric substrate, so that metal dust is prevented from entering the surface acoustic wave element during and after mounting in the package, and a short circuit may occur. A surface acoustic wave device free from defects can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a surface acoustic wave device using the surface acoustic wave device shown in FIG.

FIG. 3 is a manufacturing process diagram showing a method for manufacturing the surface acoustic wave device shown in FIG. 1;

FIG. 4 is a manufacturing process diagram showing a method for manufacturing the surface acoustic wave device shown in FIG. 1;

FIG. 5 is a manufacturing process diagram showing a method for manufacturing the surface acoustic wave device shown in FIG. 1;

FIG. 6 is a top view of a conventional surface acoustic wave device.

[Explanation of symbols]

 Reference Signs List 1 piezoelectric substrate 2 electrode 3 coupling layer 10 surrounding wall 17 lid 100 input / output electrode

Claims (7)

[Claims] A piezoelectric substrate, at least one set of comb-shaped electrodes provided on the piezoelectric substrate, at least one set of input and output electrodes connected to the comb-shaped electrodes, and a cover for covering the comb-shaped electrodes on the substrate. And a surrounding body provided so that a part of the input / output electrodes is exposed, wherein at least one corner of the surrounding body is obtuse. 2. The surface acoustic wave device according to claim 1, wherein the enclosure is formed using a photosensitive resin. 3. The surface acoustic wave device according to claim 1, wherein the enclosure on the input and output electrodes has a concave portion. 4. The surface acoustic wave device according to claim 1, wherein at least one coupling layer is provided between the envelope and the piezoelectric substrate. 5. The surface acoustic wave device according to claim 4, wherein the coupling layer is a monolayer. 6. The surface acoustic wave device according to claim 4, wherein the coupling layer is formed using a silane-based compound. 7. The surface acoustic wave device according to claim 5, wherein a surface area of the coupling layer is larger than an area of the surrounding body in contact with the piezoelectric substrate.