JP2007019943A - Surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin surface acoustic wave device having good performance by preventing permeation of humidity. <P>SOLUTION: In this surface acoustic wave device, a sealing film 6 for preventing humidity permeation into a vibration space 5 is provided on the external periphery of a space forming member 4 for forming the vibration space 5 in a state of surrounding an interdigital portion 2a. Permeation of moisture and a gas into the vibration space 5 (interdigital portion 2a side) can be positively prevented and the device having good performance can be obtained, and the degree of hermetical sealing of the vibration space 5 can be improved by the sealing film 6. Further, since the height of the sealing film 6 from a piezoelectric substrate 1 is smaller than the tip of a conductor bump 3, the thickness is thin, thereby realizing thin thickness of the device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface acoustic wave device suitable for application to resonators and filters used in various electric devices.

  FIG. 3 is a cross-sectional view of a main part of a conventional surface acoustic wave device. Next, the configuration of the conventional surface acoustic wave device will be described with reference to FIG. Although not shown here, the piezoelectric substrate 51 is provided with a comb-tooth electrode having a comb-tooth portion and an electrode, and the piezoelectric substrate 51 is formed with a vibration space portion 52 in a state of surrounding the comb-tooth portion. A space forming member 53 made of a dry film resist is provided.

  The conductor bump 54 is provided on the electrode of the comb-teeth electrode, and the protective resin portion 55 made of an insulating resin is exposed on the lower surface of the piezoelectric substrate 51 in a state where the tip of the conductor bump 54 is exposed and the space forming member 53 is covered. Provided.

The height of the protective resin portion 55 from the piezoelectric substrate 51 is larger than the tip portion of the conductor bump 54, and a terminal 56 embedded in the protective resin portion 55 and connected to the mother substrate of the external device is connected to the conductor bump 54. Thus, a conventional surface acoustic wave device is formed (see, for example, Patent Document 1).
JP 2002-232260 A (page 4-5, FIG. 1)

  However, in the conventional surface acoustic wave device, since the space forming member 53 for forming the vibration space portion 52 is formed of a dry film resist, moisture enters the vibration space portion 52 and deteriorates the performance. Further, even if the space forming member 53 is covered with the protective resin portion 55, the protective resin portion 55 is not able to improve the performance because moisture enters the protective resin portion 55, and the protective resin portion 55 exceeds the tip of the conductor bump 54. Therefore, there is a problem that the thickness cannot be reduced due to the increase in the thickness direction.

  The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a thin surface acoustic wave device while preventing moisture from entering and obtaining good performance. There is.

  In order to achieve the above object, as a first solving means of the present invention, a piezoelectric substrate provided with a comb electrode on one side and a space forming member provided on the piezoelectric substrate to form a vibration space portion The comb-teeth electrode has a comb-teeth portion and an electrode connected to the comb-teeth portion, a conductor bump is connected to the electrode, and the space forming member comprises the comb-teeth portion An annular side wall that is attached to the piezoelectric substrate in an enclosed state and is thicker than the thickness of the comb tooth portion, and a lid that closes the opening of the side wall. A sealing film for preventing moisture from entering the portion is provided, and the height of the sealing film from the piezoelectric substrate is smaller than the tip of the conductor bump.

  As a second solution, the sealing film is connected to the side wall and provided on the piezoelectric substrate, and a space between the piezoelectric substrate and the side wall is covered with the sealing film.

  As a third solution, the sealing film is formed by forming one or more films of metal oxide, metal nitride, metal oxynitride, silicon oxide, silicon nitride, or silicon oxynitride. The configuration is as follows.

  As a fourth solution, the sealing film is formed of a multilayer film.

  As a fifth solution, the sealing film is formed by sputtering or CVD.

  As a sixth solution, the side wall and the lid of the space forming member are formed of different members and are formed of the same material or different materials.

  As a seventh solving means, a first protective resin portion is provided on the sealing film with the conductive bumps exposed, and the first protective resin portion from the piezoelectric substrate is provided. The height was configured to be smaller than the tip of the conductor bump.

  Further, as an eighth solving means, the second protective resin portion is provided on the other surface of the piezoelectric substrate.

  In the surface acoustic wave device of the present invention, a sealing film for preventing moisture from entering the vibration space portion is provided on the outer peripheral surface of the space forming member for forming the vibration space portion in a state of surrounding the comb tooth portion. Therefore, it is possible to reliably prevent moisture and gas from entering the vibration space (comb teeth side), to obtain a good performance, and to improve the sealing degree of the vibration space by the sealing film In addition, since the height of the sealing film from the piezoelectric substrate is smaller than the tip of the conductor bump, the thickness can be reduced and the thickness can be reduced.

  In addition, the sealing film is provided on the piezoelectric substrate connected from the side wall, and the gap between the piezoelectric substrate and the side wall is covered with the sealing film, so that the sealing film exists at the boundary between the piezoelectric substrate and the side wall, It is possible to more reliably prevent moisture and gas from entering the vibration space portion and seal it.

  In addition, since the sealing film is formed of one or more films of metal oxide, metal nitride, metal oxynitride, silicon oxide, silicon nitride, or silicon oxynitride, the sealing film has excellent moisture resistance. A stop film can be formed.

  Further, since the sealing film is formed of a multilayer film, it is possible to obtain a more reliable one that prevents moisture and gas from entering and seals.

  In addition, since the sealing film is formed by sputtering or CVD, the sealing film has a good adhesion and is thin and accurate.

Further, since the side wall and the lid of the space forming member are formed of different members, the formation of the space forming member is facilitated, and the same material or different materials are used. A thing with a degree of freedom is obtained.

  Further, since the first protective resin portion is provided on the sealing film with the conductor bumps exposed, the space forming member can be protected from external force, and the first protective resin portion from the piezoelectric substrate can be protected. Since the height is smaller than the tip of the conductor bump, the thickness is small and the thickness can be reduced.

  Further, since the second protective resin portion is provided on the other surface of the piezoelectric substrate, the piezoelectric substrate can be protected from external force.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a main part according to a first embodiment of a surface acoustic wave device of the present invention, and FIG. It is principal part sectional drawing which concerns on an example, Next, if the structure which concerns on 1st Example of the surface acoustic wave device of this invention is demonstrated based on FIG. 1, in one surface (lower surface) of the square piezoelectric substrate 1, A comb-teeth electrode 2 is provided. The comb-teeth electrode 2 includes a comb-teeth portion 2a and an electrode 2b connected to the comb-teeth portion 2a, and a conductive bump 3 formed of solder or the like is provided on the electrode 2b. Is provided.

  The box-shaped space forming member 4 is formed by an annular side wall 4 a attached (adhered) to the lower surface of the piezoelectric substrate 1 and a lid 4 b that closes the opening of the side wall 4 a. 4a is formed thicker than the comb tooth portion 2a and is disposed so as to surround the comb tooth portion 2a. By providing the space forming member 4 on the piezoelectric substrate 1, a sealed vibration space portion 5 is formed. In addition, the space forming member 4 is arranged between the conductor bumps 3.

  Further, the side wall 4a and the lid 4b of the space forming member 4 are formed by separate members in this embodiment, and the side wall 4a is made of, for example, an inorganic insulating material such as silicon oxide, or an ultraviolet ray such as epoxy, polyimide, or acrylic. An insulating material made of a curable resin is used, and the cover 4b is made of an insulating material made of an ultraviolet curable resin such as epoxy, polyimide, acrylic, or an inorganic material such as glass. Can be appropriately selected and used.

  Although the side wall 4a and the lid 4b are described as being formed by separate members in this embodiment, the side wall 4a and the lid 4b may be integrated into one component.

  The sealing film 6 for preventing moisture from entering the vibration space 5 is formed across the entire outer peripheral surface of the space forming member 4 and the lower surface of the piezoelectric substrate 1 from the space forming member 4. By being provided on the entire outer peripheral surface of the space forming member 4, moisture and gas can be prevented from entering the vibration space portion 5 from the space forming member 4 side, and the sealing film 6 is formed from the space forming member 4 to the piezoelectric substrate. By being provided across the lower surface of 1, the penetration of moisture and gas into the vibration space 5 from the boundary between the piezoelectric substrate 1 and the side wall 4a is prevented.

  In addition, the sealing film 6 is provided on the lower surface of the piezoelectric substrate 1 excluding the connection portion of the conductor bump 3 to the electrode 2b, and the sealing film 6 includes a metal oxide, a metal nitride, a metal oxynitride, It is formed of one film of silicon oxide, silicon nitride, or silicon oxynitride, or a multilayer film of the same kind or different kinds, and the sealing film 6 is manufactured by sputtering or CVD (vapor deposition). Be filmed.

  The first protective resin portion 7 made of an insulating material is provided on the lower surface of the piezoelectric substrate 1 so as to cover the sealing film 6 with the front end portion of the conductor bump 3 exposed, and the first protective resin portion 7 is formed from the piezoelectric substrate 1. The height of the protective resin portion 7 is formed to be smaller than the tip of the conductor bump 3, and the first protective resin portion 7 is, for example, a thermosetting resin such as epoxy, polyimide, or silicone, or an ultraviolet curable resin. It is formed with.

  Further, the second protective resin portion 8 made of an insulating material is provided so as to cover the other surface (upper surface) of the piezoelectric substrate 1, and the second protective resin portion 8 is made of, for example, epoxy, polyimide, or silicone. The surface acoustic wave device of the present invention is formed by a thermosetting resin such as UV curable resin or the like.

  Although the surface acoustic wave device of the present invention having such a configuration is not shown here, the conductor bump 3 is placed on the wiring pattern of the mother board of the external device and connected to the wiring pattern. Yes.

  FIG. 2 shows a second embodiment of the surface acoustic wave device according to the present invention. The second embodiment will be described. The second embodiment is an insulating film with the lead terminal 9 made of a conductive material connected to the electrode 2b. It is drawn on the sealing film 6 and the conductor bump 3 is connected to the lead terminal 9 at a position away from the electrode 2b so as to correspond to the wiring pattern of the mother board. The structure is the same as that of the first embodiment, and the same parts are denoted by the same reference numerals, and the description thereof is omitted here.

It is principal part sectional drawing which concerns on 1st Example of the surface acoustic wave device of this invention. It is principal part sectional drawing which concerns on 2nd Example of the surface acoustic wave device of this invention. It is principal part sectional drawing concerning the conventional surface acoustic wave device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric substrate 2 Comb-tooth electrode 2a Comb-tooth part 2b Electrode 3 Conductor bump 4 Space formation member 4a Side wall 4b Cover body 5 Vibration space part 6 Sealing film 7 1st protection resin part 8 2nd protection resin part 9 Lead-out terminal

Claims (8)

A piezoelectric substrate provided with a comb-teeth electrode on one surface side and a space forming member provided on the piezoelectric substrate to form a vibration space, the comb-teeth electrode comprising a comb-teeth portion and the comb-teeth portion A conductive bump is connected to the electrode, and the space forming member is attached to the piezoelectric substrate in a state of surrounding the comb tooth portion, and is thicker than the thickness of the comb tooth portion. An annular side wall and a lid that closes the opening of the side wall are provided. A sealing film for preventing moisture from entering the vibration space is provided on the outer peripheral surface of the space forming member, and the piezoelectric substrate The surface acoustic wave device is characterized in that the height of the sealing film from is smaller than the tip of the conductor bump. The surface acoustic wave according to claim 1, wherein the sealing film is provided on the piezoelectric substrate so as to be connected from the side wall, and the space between the piezoelectric substrate and the sidewall is covered with the sealing film. Devices. The sealing film is formed of one or more films of metal oxide, metal nitride, metal oxynitride, silicon oxide, silicon nitride, or silicon oxynitride. 3. The surface acoustic wave device according to 1 or 2. 4. The surface acoustic wave device according to claim 3, wherein the sealing film is formed of a multilayer film. 5. The surface acoustic wave device according to claim 3, wherein the sealing film is formed by sputtering or CVD. The surface according to any one of claims 1 to 5, wherein the side wall and the lid of the space forming member are formed of different members, and are formed of the same material or different materials. Elastic wave device. A first protective resin portion is provided on the sealing film in a state where the conductive bump is exposed, and a height of the first protective resin portion from the piezoelectric substrate is set at a tip of the conductive bump. The surface acoustic wave device according to any one of claims 1 to 6, wherein the surface acoustic wave device is smaller. The surface acoustic wave device according to any one of claims 1 to 7, wherein a second protective resin portion is provided on the other surface of the piezoelectric substrate.

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