JP2003037474A - Surface acoustic wave device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave device which can be mounted at high-density by enhancing the reliability on bump junctions. SOLUTION: This surface acoustic wave device has a piezoelectric substrate, a comb-toothed electrode and an electrode pad formed at one main surface of the piezoelectric substrate, a bump-formed on the electrode pad, an ultrathin sheet arranged in opposition to the one main surface of the piezoelectric substrate, a base substrate connected electrically with the bump and bonded to the ultra-thin sheet, a rear electrode arranged at the rear of the base substrate, and a top protective film arranged on the ultra-thin sheet and covering the face opposed to the side face and one main surface of the piezoelectric substrate. The ultra-thin sheet has a first hole piercing the bump and a second hole, forming specified space around the comb-toothed electrode. The base substrate is electrically connected to the bump piercing the first hole of the ultrathin sheet.

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 and a method of manufacturing the same, and more particularly, to a surface acoustic wave device in which a surface acoustic wave element is mounted on a base substrate using a flip chip bonding method and a method of manufacturing the same. Regarding

[0002]

2. Description of the Related Art In recent years, many surface acoustic wave devices have been used as elements such as filters, delay lines, and oscillators of electronic devices that use radio waves. In addition, electronic devices used in the field of mobile communication and the like are required to be reduced in size and have high reliability, and due to this reduction, miniaturization of surface acoustic wave devices is also required.

The surface acoustic wave element applies an electric signal to an input interdigital transducer of a comb-shaped electrode formed on a piezoelectric substrate, converts it into a surface acoustic wave, and transmits it on the piezoelectric substrate. Then, the surface acoustic wave reaching the output interdigital transducer of the other comb-teeth electrode is converted into an electric signal again and taken out to the outside.

The conventional surface acoustic wave device has an FDB (face down bonding) structure. Bumps are formed on the surface acoustic wave element using a bump bonding apparatus. Then, the surface acoustic wave element is bonded to a conventional ceramic base substrate using a flip chip bonder device. After that, the cap is bonded to the ceramic base substrate to seal the surface acoustic wave element. The surface elastic breaking device configured as described above is inexpensive and rich in mass production, but there is a limit to size reduction in the direction horizontal to the element surface in order to secure a region for bonding the cap.

This problem is solved by using a thermosetting resin instead of the cap to seal the element. As shown in FIG. 5, the surface acoustic wave device 5 is formed by using the bumps 53.
1 is bonded to the surface of a flat ceramic base substrate 55 by the above method. Then, the surface of the base substrate 55 including the surface acoustic wave element 51 is covered with the fluid resin material 5
8 and the resin material 58 is thermally cured. The horizontal size is reduced by not using the cap.
At the same time, since there is no cap, size reduction in the direction perpendicular to the surface of the element 51 is also realized.

Further, on one main surface of the surface acoustic wave element 51,
A comb-tooth electrode 52a for exciting and detecting the surface acoustic wave is formed, and a dam 60 made of polyimide resin is formed outside the comb-tooth electrode 52a. By performing flip chip bonding, the area around the comb-teeth electrode 52a is dam 60.
Surrounded by. The resin material 58 is stopped by the dam 60 and does not cover the comb-teeth electrode 52a.
The comb-teeth electrode 52a arranged inside the dam 60 is protected. The dam 60 is described in detail in JP-A-5-55303.

[0007]

However, any of the conventional package structures using the cap or the thermosetting resin described above is based on the use of the ceramic base substrate 55. The ceramic base substrate 55 has a technical problem in terms of strength, and there is a limit to its thickness reduction.

Further, since the ceramic base 54 has almost no flexibility, the bump 5 is formed in the bump forming process and the FDB process of the element 51 through the bump.
There was a problem that 5 was easy to come off due to stress or the like.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to improve the bonding reliability of bumps and enable high-density mounting of a surface acoustic wave device. It is to provide the manufacturing method.

[0010]

In order to achieve the above object, the first feature of the present invention is to provide a piezoelectric substrate, comb-teeth electrodes formed on one main surface of the piezoelectric substrate, and one main surface of the piezoelectric substrate. Electrically connected to the bumps, the electrode pads connected to the comb-teeth electrodes, the bumps formed on the electrode pads, the ultra-thin sheet arranged to face one main surface of the piezoelectric substrate. And the base substrate adhered to the ultra-thin sheet, and arranged on the surface opposite to the surface to which the bumps of the base substrate are connected,
The surface acoustic wave device has a back electrode connected to the bump and a top surface protective film that is disposed on the ultrathin sheet and covers the side surface of the piezoelectric substrate and the surface facing the one main surface. Here, the ultra-thin sheet has a first hole for penetrating the bump and a second hole for forming a predetermined space around the comb-teeth electrode. In addition, the base substrate is electrically connected to the bumps that penetrate the first holes of the ultrathin sheet.

According to the first aspect of the present invention, since the ultrathin sheet is arranged between the piezoelectric substrate and the base substrate,
The upper surface protective film does not cover the comb-teeth electrode formed on the one main surface of the piezoelectric substrate. The comb-teeth electrode is the second thin sheet.
The surface of the surface acoustic wave device is protected by the predetermined space formed by the holes, and the operating characteristics of the surface acoustic wave device are not impaired.

Further, since the top surface protective film covers the side surface and the one main surface of the piezoelectric substrate, there is no fear that the bump will come off. Even when a base substrate that does not have flexibility such as ceramics is used, the bumps will not come off due to stress in the manufacturing process and the mounting process of electrical elements, and the bonding reliability can be improved, and the package size can be reduced. can do.

A second feature of the present invention is: (1) a step of forming a metal pattern including a comb-shaped electrode and an electrode pad on one main surface of the piezoelectric substrate; and (2) an electrode pad for an ultrathin sheet. A step of forming a first hole at a position corresponding to, and a second hole at a position corresponding to the comb-teeth electrode; (3) a step of adhering the ultrathin sheet to the surface of the base substrate; ) A step of forming a back electrode on the back surface of the base substrate, and (5) disposing one main surface of the piezoelectric substrate so as to face the front surface of the base substrate, and bumping the electrode pad and the base substrate through the first hole A method of manufacturing a surface acoustic wave device, which comprises a step of electrically connecting via a piezoelectric material and a step (6) of covering a side surface of the piezoelectric substrate and a surface facing the one main surface with a polymer material. Is.

According to the second aspect of the present invention, since the ultrathin sheet is arranged between the piezoelectric substrate and the base substrate,
The polymer material does not cover the comb-teeth electrode formed on the one main surface of the piezoelectric substrate. The comb-teeth electrode is protected by a predetermined space formed by the second hole of the ultrathin sheet,
The operating characteristics of the surface acoustic wave device are not impaired.

Further, since the polymer material covers the side surface of the piezoelectric substrate and the surface facing the one main surface, there is no fear that the bump will come off. Even when a base substrate that does not have flexibility such as ceramics is used, the bumps will not come off due to stress in the manufacturing process and the mounting process of electrical elements, and the bonding reliability can be improved, and the package size can be reduced. can do.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and width of layers, the ratio of the thickness of each layer, and the like are different from actual ones. Further, it is needless to say that the drawings include parts in which dimensional relationships and ratios are different from each other.

(First Embodiment) FIG. 1A is a sectional view showing a surface acoustic wave device according to a first embodiment of the present invention. As shown in FIG. 1, the surface acoustic wave device includes a piezoelectric substrate 1 and a comb-teeth electrode 2 formed on one main surface of the piezoelectric substrate 1.
An electrode pad 12 formed on one main surface of the piezoelectric substrate 1 and connected to the comb-teeth electrode 2, a bump 3 formed on the electrode pad 12, and facing the one main surface of the piezoelectric substrate 1. Ultrathin sheet (polyimide sheet) 4 and bumps 3 placed
To the ultra-thin sheet 4, a base substrate 5 electrically connected to the ultra-thin sheet 4, a back electrode 6 arranged on the surface of the base substrate 5 opposite to the surface to which the bumps 3 are connected, and the ultra-thin sheet 4
And a top surface protective film 8 that covers the side surface of the piezoelectric substrate 1 and the surface facing the one main surface. Ultra thin sheet 4
Is the first hole 13 for penetrating the bump 3 and the comb-teeth electrode 2
And a second hole 14 that forms a predetermined space 9 around the. The bump 3 penetrates the first hole 13 of the ultrathin sheet 4 and is connected to the base substrate 5. The back surface electrode 6 is connected to the bump 3 via a through hole.

As the piezoelectric substrate 1, lithium tantalate (LiTaO ₃ ) and lithium niobate (LiNb) are used.
A single crystal substrate made of O ₃ ), a lithium barium oxide substrate (LiB ₄ O ₇ ), sapphire, quartz (SiO ₂ ), or the like can be used. Alternatively, instead of these single crystal substrates, lead titanate (PbTiO ₃ ), lead zirconate titanate (PbZrTiO ₃ (PZT)),
Alternatively, it is also possible to use a piezoelectric ceramic substrate made of these solid solutions.

Although not shown in the drawings, the comb-teeth electrode 2 is a metal electrode having two or more comb-teeth-like planar shapes that mesh with each other. The surface acoustic wave (SAW) is excited and detected by the comb-teeth electrode 2. An electric signal is applied to the input interdigital transducer of the comb-teeth electrode 2, which is converted into a surface acoustic wave and transmitted on the piezoelectric substrate 1. Further, the surface acoustic wave reaching the output interdigital transducer of the other comb-teeth electrode 2 is converted into an electric signal again and can be taken out to the outside. The metal used as the material of the comb-teeth electrode 2 is Al (aluminum) or an alloy containing Al as a main component. In the latter case, copper (C
u), silicon (Si), etc. can be used.

The bumps 3 are arranged outside the comb-teeth electrode 2 and connect the electrode pads 12 to internal wiring (not shown) on the base substrate 5. The electrode pad 12 is connected to the comb-teeth electrode 2 together with the comb-teeth electrode 2 by a metal wiring or the like formed on the piezoelectric substrate 1. Here, bump 4
Is used as a gold bump having gold (Au) as a main component.

A polyimide sheet 4 is used as the ultrathin sheet. The polyimide sheet 4 has an adhesive layer 15 and is adhered to the base substrate 5 by the adhesive layer 15. The first hole 13 formed in the polyimide sheet 4 is formed corresponding to the position of the electrode pad 12, and has a size sufficient for penetrating the bump 3.
The second hole 14 formed in the polyimide sheet 4
Are formed so as to face the position of the comb-teeth electrode 2, and have a size sufficient to form a predetermined space 9 around the comb-teeth electrode 2.

The base substrate 5 serves to externally input and output electric signals, and further serves as a basis for protecting the external force, liquids such as moisture and water, and forming a shape. A ceramic substrate is used as the base substrate 5. Although illustration is omitted, internal wiring joined to the bumps 3 is formed on the base substrate 5. The internal wiring is connected to the back surface electrode 6 through a through hole formed on the side surface of the base substrate 5. The back electrode 6 is a gold-plated film.

The upper surface protective film 8 is composed of the piezoelectric substrate 1 and the comb-teeth electrode 2.
It also has a function of protecting the surface acoustic wave element including the electrode pad 12 and the like from environmental stress and mechanical stress.
For example, as the upper surface protective film 8, epoxy resin, polyimide resin, PP / EPR polymer alloy (PP / Ethylene)
Propylene Rubber Blend), TEX (manufactured by Tonen Chemical Co., Ltd., polyolefin-based TPE (Polyolefine Thermoplas)
tic Elastomer)), Toughprene (manufactured by Asahi Kasei Corporation,
SBS (Styrene-Butadiene-Styrene Block Copolyme
r)), Maxloy A (manufactured by Japan Synthetic Rubber Co., Ltd.), X
-9 (PA / PAR (PA / Polyary manufactured by Unitika Ltd.
late)), Tenac (PAM / TP manufactured by Asahi Kasei Corporation)
Polymeric materials such as U (POM / Thermoplastic Polyurethane) can be used.

FIG. 1 (b) is a transparent perspective view of the surface acoustic wave device shown in FIG. 1 (a). In FIG. 1 (b),
In order to show a planar configuration between the polyimide sheet 4 and the one main surface of the piezoelectric substrate 1, the surface acoustic wave elements (1, 2, 12) and the upper surface protective film 8 are made to penetrate, and the bumps 3, the first holes are formed. 1
3, the plane arrangement of the second hole 14 and the space 9 is shown. Also,
FIG. 1A is a cross-sectional view taken along the section line AA ′ of FIG. As shown in FIG. 1B, a second hole 14 for forming and protecting a space 9 around the comb-teeth electrode 2 is arranged in the central portion of the polyimide sheet 4. The base substrate 5 is exposed on the bottom surface of the second hole 14. A total of six first holes 13 and bumps 3 penetrating the first holes 13 are arranged outside the second holes 14. An input signal, an output signal, or a ground potential is supplied from the back surface electrode 6 to the surface acoustic wave element via these bumps 3. Each of these bumps 3 is connected to a back surface electrode 6.
Further, the polyimide sheet 4 and the base substrate 5 have a rectangular shape, and through holes 7 that connect the back surface electrode 6 and the internal wiring are formed at the four corners.

FIGS. 2A to 2C are cross-sectional views of main steps showing a method of manufacturing the surface acoustic wave device shown in FIGS. 1A and 1B.

(A) First, the comb-teeth electrode 2, the electrode pad 12, the comb-teeth electrode 2 and the electrode pad 12 are formed on one main surface of the piezoelectric substrate 1.
A surface acoustic wave element is manufactured by forming a metal pattern including a wiring connecting between the elements. Specifically, a metal film (Al film) having a film thickness of about several hundreds nm is formed on the piezoelectric substrate 1 by using a magnetron type sputtering device. A resist film is formed on this metal film, and the resist film is exposed and developed by photolithography. Then, using this resist film as a mask, the metal film is selectively etched by a reactive ion etching (RIE) method to form a metal pattern.

(C) Next, the bumps 3 are formed on the electrode pads 12 by the bump bonding method. Specifically, the electrode pad 1 is used while vibrating the bump 3 with ultrasonic waves.
Crimp to 2. At this time, by heating the vicinity of the electrode pad 12, the adhesiveness between the bump 3 and the electrode pad 12 can be improved. As described above, gold (Au) bumps are used as the bumps 3. The gold (Au) bump has good adhesiveness to the electrode pad 12, and has low electric resistance at the contact portion. The height of the bump 3 is 20 to 5
About 0 μm is preferable.

(D) On the other hand, the polyimide ultrathin sheet 4 having the adhesive layer 15 for adhering to the base substrate 5
To prepare. Then, as shown in FIG. 2A, in order to penetrate the bumps 3 formed on the electrode pads 12 through the polyimide sheet 4, the first holes 13 are formed at positions corresponding to the electrode pads 12. To form. Similarly, the second hole 14 is formed in the polyimide sheet 4 at a position corresponding to the comb electrode 2.

(E) Next, the polyimide sheet 4 is adhered to the surface of the base substrate 5 via the adhesive layer 15.

(V) Next, the back surface electrode 6 is formed on the back surface of the base substrate 5. Specifically, on the back surface of the base substrate 5,
A gold (Au) plating film is formed by using a plating method or the like. Then, the back electrode 6 corresponding to each bump 3 is formed by performing a predetermined patterning.

(G) Next, as shown in FIG. 2B, one main surface of the piezoelectric substrate 1 is arranged so as to face the surface of the base substrate 5, and the electrode pad 12 and the electrode pad 12 are formed through the first holes 13. The base substrate 5 is electrically connected via the bumps 3. That is,
The surface acoustic wave device is mounted on the base substrate 5 using the flip chip bonding method through the first hole 13 formed in the polyimide sheet 4. Specifically, regarding the surface acoustic wave element on which the bump 3 is formed, the comb-teeth electrode 2
The surface on which is formed the polyimide sheet 4 of the base substrate 5
It is arranged so as to face the surface on which is formed. And bump 3
The bumps 3 are pressure-bonded to the base substrate 5 through the first holes 13 while applying heating vibration to. By performing this flip chip bonding, the surface acoustic wave element (electrode pad 12) and the base substrate 5 are electrically connected via the bumps 3 (see FIG. 2C). Also, the comb-teeth electrode 2
A space 9 is formed around the comb-teeth electrode 2 by the second hole 14 formed at a position corresponding to. Further, a dam is formed around the comb-teeth electrode 2 by the polyimide sheet 4.

A polyimide sheet 4 is arranged between the surface acoustic wave element and the base substrate 5, and the distance between the surface acoustic wave element and the base substrate 5 is determined by the thickness of the polyimide sheet 4. . Therefore, unlike normal flip-chip bonding, the distance between the polymer-based substrate 5 and the piezoelectric substrate 1 is not determined by the height of the bump 3. Therefore, the height of the bump 3 is 2 as described above.
The thickness is preferably about 0 to 50 μm, but is not limited to this range.

(H) Finally, the side surface of the piezoelectric substrate 1 and the surface (back surface) facing the one main surface are covered with a polymer material. Specifically, a thermosetting resin material (polymer material) is applied on the piezoelectric substrate 1 and the base substrate 5. Then, the surface acoustic wave element is sealed (packaged) by applying a predetermined heat treatment to cure the applied resin material. At that time, since the polyimide sheet 4 is arranged between the piezoelectric substrate 1 and the base substrate 5, the resin material is
It does not enter the gap between the piezoelectric substrate 1 and the base substrate 5. Therefore, only the side surface and the back surface of the piezoelectric substrate 1 are covered with the resin material, and one main surface of the piezoelectric substrate 1 on which the comb-teeth electrode 2 and the like are formed is not covered. That is, the dam formed around the comb-teeth electrode 2 prevents the resin material from entering the space 9 around the comb-teeth electrode 2 and protects the operating characteristics of the surface acoustic wave element. Through the above steps, FIG.
The surface acoustic wave device shown in (a) and (b) can be manufactured.

As described above, since the polyimide sheet 4 is arranged between the piezoelectric substrate 1 and the base substrate 5, the polymer material enters the gap between the piezoelectric substrate 1 and the base substrate 5. There is nothing. That is, the upper surface protective film 8
However, it does not cover the comb-teeth electrode formed on the main surface of the piezoelectric substrate. The comb-teeth electrode 2 is protected by the predetermined space 9 formed by the second hole of the polyimide sheet 4, and the operating characteristics of the surface acoustic wave device are not impaired.

Further, since the upper surface protective film 8 covers the side surface of the piezoelectric substrate 1 and the surface facing the one main surface, the bump 3 is not likely to come off. Even when a base substrate having no flexibility such as ceramics is used, the defect that the base substrate made of ceramics is not flexible is compensated, and the bumps 3 are not detached due to stress or the like in the manufacturing process and the mounting process of the electric element, and the bonding is performed. The reliability can be increased and the package size can be reduced.

Further, the periphery of the comb-teeth electrode 52a is surrounded by the second hole 14 forming the space 9. That is, the polyimide sheet 4 is formed around the comb-teeth electrode 52a.
A dam consisting of Therefore, unlike the conventional case, it is not necessary to form the dam 60 made of polyimide resin on the outer side of the comb-teeth electrode 52a, and it is possible to obtain effects such as a reduction in processes and a reduction in cost.

In the first embodiment, the gold bumps containing gold (Au) as the main component are used as the bumps 4, but solder balls may be used instead of the gold bumps.

(Second Embodiment) In the second embodiment of the present invention, FIG. 3 shows a case where the bump connection between the electrode pad 12 and the base substrate 5 is performed by an embedded electrode made of molten solder. This will be described with reference to a) and (b).

As shown in FIG. 3A, the surface acoustic wave device according to the second embodiment is embedded in the first hole 13 instead of the bump 3 shown in FIG. It has a buried electrode 10 for electrically connecting the electrode pad 12 and the base substrate 5. The embedded electrode 10 is made of solder balls or solder plating. Crushed bump 3
Unlike the above, the embedded electrode 10 is bonded to the electrode pad 12 by filling back the first hole 13 exposed by the base substrate (internal wiring) 5 on the bottom surface. Therefore, the first hole 13
The inside of is filled with the embedded electrode 10.

As shown in FIG. 3B, six first holes 13 are arranged outside the second holes 14, and each of the first holes 13 is formed.
An embedded electrode 10 is embedded in the. Other configurations are similar to those of the surface acoustic wave device shown in FIGS. 1A and 1B, and detailed description thereof will be omitted.

The surface acoustic wave device shown in FIGS. 3A and 3B can be manufactured by the following method.

(A) First, a surface acoustic wave element is manufactured by forming a metal pattern composed of the comb-teeth electrode 2, the electrode pad 12 and the like on the piezoelectric substrate 1. The bumps 3 are not formed by the bump bonding method.

(B) On the other hand, the first polyimide sheet 4
Hole 13 and second hole 14 are formed. Then, it is adhered to the base substrate 5 via the adhesive layer 15. Base substrate 5
A back surface electrode (gold plated film) 6 is formed on the back surface of.

(C) Next, the first polyimide sheet 4
A solder ball is embedded in the hole 13 of the. Or the first hole 1
The inside of 3 is plated with solder. Then, one main surface of the piezoelectric substrate 1 is pressed against the polyimide sheet 4. At this time, the electrode pad 12 on the piezoelectric substrate 1 is arranged so as to be directly above the first hole 13. Then, the solder is melted and joined to the electrode pad 12.

(D) Finally, the upper surface protective film 8 is formed,
The surface acoustic wave device shown in FIGS. 3A and 3B can be manufactured.

(Third Embodiment) In the third embodiment of the present invention, the surface acoustic wave device shown in FIGS. 1A and 1B is embedded in the first hole 13. A case will be described with reference to FIGS. 4A and 4B in which the bump 12 and the conductive paste for electrically connecting the electrode pad 12 and the base substrate 5 are further provided.

As shown in FIG. 4A, bumps 3 for electrically connecting the electrode pads 12 and the base substrate 5 are arranged inside the second holes 13. The inside of the first hole 13 is backfilled with the conductive paste 11.
That is, the periphery of the bump 3 is filled with the conductive paste 11. The conductive paste 11 has a function of electrically connecting the electrode pad 12 and the base substrate 5 similarly to the bump 3, and plays a role of complementing the reliability of electrical connection and mechanical connection by the bump 3. Is playing. here,
Complementary reliability of electrical connection means reduction of connection resistance between the electrode pad 12 and the base substrate 5, and supplementary reliability of mechanical connection means connection between the electrode pad 12 and the base substrate 5. Shows improved strength. As the conductive paste 11, a silver paste or the like can be used.

As shown in FIG. 4B, six first holes 13 are arranged outside the second holes 14, and each of the first holes 13 is formed.
At the same time as the bumps 3 are arranged inside, the conductive paste 11 is embedded. Other configurations are
Since it is similar to the surface acoustic wave device shown in FIGS. 1A and 1B, detailed description thereof will be omitted.

The surface acoustic wave device shown in FIGS. 4A and 4B can be manufactured by the following method.

(A) First, a surface acoustic wave element is manufactured by forming a metal pattern composed of the comb-teeth electrode 2, the electrode pad 12 and the like on the piezoelectric substrate 1. Then, the bump 3 is formed on the electrode pad 12 using the bump bonding method.

(B) On the other hand, the first polyimide sheet 4
Hole 13 and second hole 14 are formed. Then, it is adhered to the base substrate 5 via the adhesive layer 15. Base substrate 5
A back surface electrode (gold plated film) 6 is formed on the back surface of.

(C) Next, the first polyimide sheet 4
A conductive paste (silver paste) 11 is embedded in the hole 13 of the. Then, the surface acoustic wave element is mounted on the base substrate 5 by using the flip chip bonding method. In particular,
Regarding the surface acoustic wave element having the bumps 3, the surface on which the comb-teeth electrode 2 is formed is arranged so as to face the surface of the base substrate 5 on which the polyimide sheet 4 is formed. Then, the bump 3 is attached to the first hole 13 while applying heating vibration to the bump 3.
It is pressure-bonded to the base substrate 5 through. At the same time, the conductive paste 11 is also heated and the organic solvent in the paste is volatilized and hardened. As a result, the electrode pad 12 and the base substrate 5 are also connected by the conductive paste 11.

(D) Finally, the upper surface protective film 8 is formed,
The surface acoustic wave device shown in FIGS. 4A and 4B can be manufactured.

As described above, the conductive paste 11
By using, the connection resistance between the electrode pad 12 and the base substrate 5 can be reduced, and the connection strength between the electrode pad 12 and the base substrate 5 can be improved.

(Other Embodiments) As described above, the present invention has been described by the first to third embodiments, but the description and drawings forming a part of this disclosure limit the present invention. Should not be understood. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

In the first to third embodiments of the present invention, gold bumps, solder balls, solder plating, are used as electrical connection means between the electrode pads 12 and the base substrate 5.
Although the case where silver paste or the like is used is shown, the present invention is not limited to this. In addition to these, a conductive substance such as a gold-plated material, copper, a copper-plated material, a bump made of aluminum or the like, plating, a conductive paste, or the like can be used.

Although the surface acoustic wave device has been described as an example of the electronic component device, the present invention can be similarly applied to other electronic component devices using the bump bonding method.

As described above, it should be understood that the present invention includes various embodiments and the like not described here. Therefore, the present invention is limited only by the matters specifying the invention according to the scope of claims appropriate from this disclosure.

[0059]

As described above, according to the present invention,
It is possible to provide a surface acoustic wave device capable of improving the bonding reliability of bumps and enabling high-density mounting, and a method for manufacturing the same.

[Brief description of drawings]

FIG. 1A is a sectional view showing a surface acoustic wave device according to a first embodiment of the present invention. Figure 1 (b) shows
FIG. 2 is a transparent perspective view of the surface acoustic wave device shown in FIG.

2A to 2C are schematic diagrams of FIG. 2A to FIG.
FIG. 6 is a main step sectional view showing the method of manufacturing the surface acoustic wave device shown in FIGS.

FIG. 3A is a sectional view showing a surface acoustic wave device according to a second embodiment of the present invention. Figure 3 (b) shows
FIG. 4 is a transparent perspective view of the surface acoustic wave device shown in FIG.

FIG. 4A is a sectional view showing a surface acoustic wave device according to a third embodiment of the present invention. Figure 4 (b) shows
FIG. 5 is a transparent perspective view of the surface acoustic wave device shown in FIG.

FIG. 5 is a cross-sectional view showing a conventional surface acoustic wave device having a dam.

[Explanation of symbols]

1 Piezoelectric substrate 2 comb electrodes 3 bumps 4 Polyimide sheet (ultra-thin sheet) 5 base board 6 Back electrode 7 through holes 8 Top surface protective film 9 space 10 Embedded electrode 11 Conductive paste 12 electrode pads 13 first hole 14 second hole 15 Adhesive layer

Claims (9)

[Claims] 1. A piezoelectric substrate, a comb-teeth electrode formed on one main surface of the piezoelectric substrate, an electrode pad formed on the one main surface of the piezoelectric substrate and connected to the comb-teeth electrode, A bump formed on the electrode pad, a first hole facing the one main surface of the piezoelectric substrate and penetrating the bump, and a predetermined space formed around the comb electrode. An ultra-thin sheet having a second hole; a base substrate electrically connected to the bump penetrating the first hole of the ultra-thin sheet and bonded to the ultra-thin sheet; Of the back electrode connected to the surface to which the bump is connected, the back electrode connected to the bump, and the surface of the piezoelectric substrate, the surface facing the side surface and the one main surface. And a top surface protective film for covering The surface acoustic wave device. 2. The surface acoustic wave device according to claim 1, wherein the base substrate is a ceramic substrate. 3. The surface acoustic wave device according to claim 1, wherein the ultra-thin sheet is a sheet made of polyimide. 4. A buried electrode, which is buried in the first hole and electrically connects the electrode pad and the base substrate, instead of the bump. Surface acoustic wave device. 5. The elasticity according to claim 1, further comprising a conductive paste embedded in the first hole and electrically connecting the electrode pad and the base substrate together with the bump. Surface wave device. 6. A step of forming a metal pattern including a comb-shaped electrode and an electrode pad on one main surface of a piezoelectric substrate, and forming a first hole at a position corresponding to the electrode pad on an ultrathin sheet. , A second position corresponding to the comb-teeth electrode
Forming a hole, a step of adhering the ultrathin sheet to the surface of a base substrate, a step of forming a back electrode on the back surface of the base substrate, and a step of forming the one main surface of the piezoelectric substrate on the base substrate. And a step of electrically connecting the electrode pad and the base substrate via a bump through the first hole, the side surface of the piezoelectric substrate using a polymer material, and And a step of coating a surface facing the one main surface. 7. The one main surface of the piezoelectric substrate is arranged so as to face the surface of the base substrate, and the electrode pad and the base substrate are electrically connected via a bump through the first hole. The step of forming comprises the steps of forming the bumps on the electrode pads using a bump bonding method and bonding the bumps to the base substrate using a flip chip bonding method. The method for manufacturing a surface acoustic wave device according to claim 6. 8. The one main surface of the piezoelectric substrate is arranged so as to face the surface of the base substrate, and the electrode pad and the base substrate are electrically connected via a bump through the first hole. The step of: embedding solder in the first hole of the ultra-thin sheet; pressing the one main surface of the piezoelectric substrate against the ultra-thin sheet; melting the solder to the electrode pad; 7. The act of joining the solder is provided.
A method for manufacturing the surface acoustic wave device according to claim 1. 9. The one main surface of the piezoelectric substrate is arranged so as to face the surface of the base substrate, and the electrode pad and the base substrate are electrically connected via a bump through the first hole. The step of forming is to form the bumps on the electrode pads using a bump bonding method, to embed a conductive paste in the first holes of the ultrathin sheet, and to use a flip chip bonding method. 7. The method of manufacturing a surface acoustic wave device according to claim 6, further comprising the step of bonding the bump onto the base substrate and simultaneously curing the conductive paste to connect to the electrode pad. .