JP3439928B2 - Surface acoustic wave device - Google Patents

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 in which a surface acoustic wave element such as a surface acoustic wave filter or a surface acoustic wave resonator is housed in a container body having terminal electrodes.

[0002]

2. Description of the Related Art Conventionally, surface acoustic wave devices have been used as filters for video signals of televisions and videos, bandpass filters for communication equipment, and resonators for high-frequency oscillation circuits of various electronic equipment.

Such a surface acoustic wave device is constructed, for example, as a so-called surface mounting type surface acoustic wave device in which a surface acoustic wave element is housed in a container body in which terminal electrodes are formed so as to be surface mountable. ing.

Here, the container is composed of, for example, one base body in which the element accommodating cavity and the terminal electrode are formed, and the other base body in the form of a flat plate or a case, both of which are sealed by seam welding or the like. Was configured.

Further, the surface acoustic wave device has a piezoelectric ceramic substrate such as lead zirconate titanate or a piezoelectric single crystal substrate such as quartz, lithium tantalate, lithium niobate or lithium tetraborate. An electrode having a predetermined shape for exciting, receiving, and reflecting the surface acoustic wave is formed. Note that this electrode also includes a wire bonding pad for making an electrical connection with the outside.

Specifically, one surface of the piezoelectric material wafer is mirror-finished, a conductor film serving as an electrode is formed by a thin film technique, and an electrode having a predetermined shape is formed by a photolithography technique. It is formed by cutting into a shape.

Such a surface acoustic wave element is planarly placed and bonded in the cavity of one of the bases via an adhesive, and the terminal electrodes of the base and the wire bonding pads of the electrodes on the piezoelectric substrate are separated from each other. , Electrically connected by a wire bonding thin wire.

After that, one substrate was covered with the other substrate so as to cover the surface acoustic wave element, and seam welding was performed on the joint surface between the one substrate and the other substrate.

[0009]

However, in the above-mentioned surface mount type surface acoustic wave device, since the wire bonding thin wire is used for the electrical connection between the terminal electrode of one of the substrates and the surface acoustic wave element. However, it is necessary to sufficiently increase the internal space of the container formed by joining one substrate and the other substrate. For this reason, when providing the excitation electrodes and the like on the piezoelectric substrate in a wide area, the surface acoustic wave The shape of the container body may become very large as compared with the shape of the element (or the piezoelectric substrate).

Further, since the surface acoustic wave element is placed and joined on one of the substrates in a plane, one of the substrates, that is,
The planar area of the container body increases, and as a surface-mounting electronic component, the mounting area on the printed wiring board increases.

Further, the cavity formed in one of the bases is formed in order to stabilize the accommodation position of the element and to shorten the length of the wire bonding fine wire. The formation of this cavity forms the structure of the base. At the same time, the structure of the terminal electrode formed on the substrate may be complicated.

Recently, various systems have been used in mobile telephones such as cellular telephones and digital cordless telephones, especially in Japan, the United States, and Europe. For example, two types of systems, namely,
The development of combined machines that can support two types of systems with different center frequencies and pass bandwidths is becoming active.
A so-called dual mode filter including a surface acoustic wave filter having two types of filter characteristics has become indispensable.

Such a dual mode filter J1
For example, as shown in FIG. 7, since two filter elements 52 and 52 are formed only on one main surface of one piezoelectric substrate 51, two sets of filter electrodes 5 for input and output are provided.
3, 53 are formed and housed and sealed in a package 61 made of ceramic or the like as shown in FIG. Here, the back surface side of the piezoelectric substrate 51 is fixed to the bottom surface 55a of the package base 55 having the input / output terminals 54, 54 on the front and back surfaces with the adhesive 56, and two of the two filter elements 52, 52 are provided.
In the pair of filter electrodes 53, 53, wire bonding wires 59 were connected to the input / output terminals 54, 54 provided on the package base 55. In the figure, 57, 58, 6
0 indicates the package 6 in addition to the package base 55.
1 is a member that constitutes 1, and 57 is an inner package side wall,
Reference numeral 58 is an outer package side wall, and 60 is a package lid.

However, if such two kinds of filter elements are formed on the same surface of the piezoelectric substrate, the required substrate area becomes very large, and there is a problem that a small surface acoustic wave device cannot be realized.

In addition, a surface acoustic wave device, which can be reduced in height, which is most required for electronic parts for mobile communication equipment, and which is extremely small as a whole, has not been realized so far.

Therefore, the present invention has been devised in view of the above-mentioned problems, and an object thereof is to realize a small surface acoustic wave device. In particular, (1) the surface acoustic wave element itself is used. (EN) Provided is a surface mounting type surface acoustic wave device which has a small size and can be electrically connected without using a wire-bonding thin wire and which can downsize the container itself. ) Low profile, which is most required for electronic components for mobile communication equipment, can be miniaturized, has high mechanical strength, is strong against lateral impact, and provides electrical connection between the element and package base. An object is to provide an easy and highly reliable surface acoustic wave device.

[0017]

In particular, a first surface acoustic wave device for achieving the above object (1) is a surface acoustic wave device having excitation electrodes formed on both main surfaces of a piezoelectric substrate. A surface acoustic wave device having a space inside and being housed in a container body in which terminal electrodes are formed in a state along the outer surface from inside the space, wherein the surface acoustic wave element is inside the container body. The surface acoustic wave elements formed on both main surfaces of the piezoelectric substrate are erected and connected to the terminal electrodes with a conductive adhesive, and the surface acoustic wave elements are electrically conductive with each other. It is characterized in that they are connected to each other.

Further, the second surface acoustic wave device for achieving the above-mentioned object (2) has a surface acoustic wave element formed by forming excitation electrodes on both main surfaces of the piezoelectric substrate and having a space inside. In the surface acoustic wave device, the surface acoustic wave device is housed in a container body having terminal electrodes formed in the space along the outer surface thereof, wherein the surface acoustic wave element has an excitation electrode formed on one main surface thereof. The excitation electrode formed on the other main surface by chip bonding is connected to the terminal electrode by wire bonding, and the flip chip bonding is surrounded by an adhesive made of resin around the conductive bump. It is characterized by

More specifically, the surface of the surface acoustic wave filter element, in which the IDT electrode, which is an exciting electrode, and the input / output electrode pad are formed on the piezoelectric substrate is a package base that is a base for forming a package (container body). A surface acoustic wave filter that is housed and sealed in a package consisting of a sealing member, etc., in which the surface acoustic wave filter element has electrodes that function as filters having different pass band characteristics on both sides of the piezoelectric substrate. In addition, the electrodes formed on one surface of the piezoelectric substrate are electrically connected to the electrical terminals of the package by wire bonding, and the electrodes formed on the other surface are electrically connected by flip chip bonding. It may be a surface acoustic wave filter.

By forming the piezoelectric substrate from lithium niobate, lithium tantalate, or lithium tetraborate, it is possible to provide a surface acoustic wave device such as a surface acoustic wave filter having more excellent characteristics. Further, by hardening the periphery of the flip-chip bonded electrode portion with an adhesive, the piezoelectric substrate can be fixed more firmly. Further, by disposing an adhesive between the surface acoustic wave filter element and the package side wall and curing it, a surface acoustic wave device having higher strength can be provided.

[0021]

As described above, the surface acoustic wave device of the present invention uses both principal surfaces of the piezoelectric substrate as the operating area of the surface acoustic wave. Therefore, a surface acoustic wave element is formed on each of both main surfaces of one piezoelectric substrate, and each of them is operated as a single surface acoustic wave element, or is applied to a dual mode or a multi mode for communication equipment. It becomes possible to do. Further, both elements can be connected to each other to operate as a composite surface acoustic wave element.

Therefore, the size of the surface acoustic wave element is simpler than that of the conventional surface acoustic wave element in which only the main surface on the front surface side of the piezoelectric substrate is used as the operation area 1 of the surface acoustic wave as in the prior art. The size can be reduced to about 1/2.

In particular, according to the first surface acoustic wave device, the piezoelectric substrate of the surface acoustic wave element is erected on one of the bases constituting the container body by utilizing the end surface of the piezoelectric substrate. Therefore, the planar area of the container can be reduced, and the mounting area on the printed wiring board can be reduced as a surface-mounted electronic component.

Further, since the electrodes formed on both main surfaces of the piezoelectric substrate and the terminal electrodes on the surface of one of the substrates can be brought close to each other in an orthogonal state, electrical connection is made by applying and curing a conductive adhesive. It can be performed. That is, an electric connection structure using a wire-bonding thin wire as in the past is not necessary, the shape of the inner space of the container can be made substantially the same as the shape of the piezoelectric substrate, and the connecting means is very It will be easy.

Furthermore, since it is not necessary to form a cavity in one of the substrates, the shape of the container body and the structure of the terminal electrode formed in the container body are simplified, and the cost can be reduced in combination with the above-mentioned connecting means. Becomes

Further, particularly in the case of the second surface acoustic wave device,
Since the excitation electrodes are provided on both main surfaces of the piezoelectric substrate, the terminal electrodes of the base and the respective excitation electrodes of the piezoelectric substrate are connected with one main surface of the piezoelectric substrate facing the main surface of the base. ,
For example, it is required for electronic parts for mobile communication devices,
Not only can the height be reduced, but also the electrode can be designed easily.

Further, since the strength of the surface acoustic wave device can be increased especially against a lateral impact, a highly reliable surface acoustic wave device can be provided.

Further, particularly in a high frequency surface acoustic wave filter, since the electric resistance of the electric connection portion greatly affects the characteristics such as loss, it is indispensable to connect with low resistance.
Since the terminal electrode of the base and the excitation electrode formed on the one main surface of the piezoelectric substrate are adhered via the conductive bump, connection can be performed easily and with low resistance, and reliability is improved. An excellent surface acoustic wave device can be provided.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface acoustic wave device of the present invention will be described below with reference to the drawings.

<First Surface Acoustic Wave Device> FIG. 1 is an external perspective view of a surface-mounting surface acoustic wave device, FIG. 2 is a cross-sectional view, and FIG. 3 is a schematic view with the other substrate omitted. Is.

Reference numeral 1 is a surface mount type surface acoustic wave device, 10 is a composite surface acoustic wave element, and 20 is a container. The composite surface acoustic wave device 10 includes two main surfaces 11a and 11b of the piezoelectric substrate 11.
The electrodes 12a and 12b for exciting, reflecting, and receiving the surface acoustic wave are formed on the upper surface, and the surface acoustic wave elements 10a and 10b are formed on the respective principal surfaces. That is, since the surface acoustic wave elements 10a and 10b are formed on both main surfaces of one piezoelectric substrate 11, the piezoelectric substrate 1
The surface acoustic wave element formed in 1 is particularly referred to as "composite surface acoustic wave element 10".

Examples of the piezoelectric substrate 11 include a piezoelectric ceramic substrate made of lead zirconate titanate or the like and a piezoelectric single crystal substrate made of quartz, lithium tantalate, lithium niobate, lithium tetraborate, or the like. , 11b
Is mirror-finished. The piezoelectric substrate 11 has a polarization direction and a predetermined cutting direction set in a predetermined direction so that a predetermined surface acoustic wave operates.

The electrodes 12a and 12b are made of aluminum, A
A metal material such as u is formed in a predetermined thickness and a predetermined shape by a thin film forming technique such as vapor deposition or sputtering and a photolithography technique. Further, the configurations of the electrodes 12a and 12b differ depending on the operation of the surface acoustic wave element.

For example, in the surface acoustic wave resonator shown in FIG. 3, the one principal surface 11 is arranged so that the surface acoustic wave element 10a on the one principal surface 11a side of the piezoelectric substrate 11 operates as a resonator.
As the electrode 12a, for example, a comb-tooth electrode which is a pair of excitation electrodes that mesh with each other, a reflector electrode for reflection sandwiching the comb-tooth electrode, and a connection pad extending from the comb-tooth electrode are formed. There is. Further, the surface acoustic wave element 10b on the other principal surface 11b side similarly operates as a resonator, although not shown in the figure, similarly, as the electrodes 12b, a pair of comb-teeth electrodes meshing with each other, and a reflection screen sandwiching the comb-teeth electrodes. Electrodes are formed.

The electrodes 12a and 12b are, for example, comb-teeth electrodes that excite surface acoustic waves, reflector electrodes that perform a reflecting action, and a surface acoustic wave element such as a planarly spread earth electrode, depending on the configuration and mode of the surface acoustic wave element. , Electrodes having various functions, and electrodes having various structures.

Then, both main surfaces 11a, 1 of the piezoelectric substrate 11 are
The surface acoustic wave devices 10a and 10b formed on the piezoelectric substrate 1b are connected to each other by the electrodes (part of the electrodes 12a and 12b) routed near the upper end surface 11c of the piezoelectric substrate 11.
They are connected to each other by a conductive connecting member 13 which is formed by applying and curing a conductive adhesive or the like on the upper end surface 11c of each of the above.

In the vicinity of the lower end surface 11d of the piezoelectric substrate 11, laid out electrodes (a part of the electrodes 12a and 12b) are formed and at least conductive with a terminal electrode 24 on the container body 20 side described later. It is electrically connected and mechanically joined by a conductive joining member 14 formed by applying and dropping an adhesive.

In the above-described embodiment, the surface acoustic wave elements 10a, 10b are provided on both main surfaces 11a, 11b of the piezoelectric substrate 11.
b is formed, and both elements 10a and 10b are connected to each other to operate as one composite surface acoustic wave element 10 for the first time, but on both main surfaces 11a and 11b of the piezoelectric substrate 11,
It is also possible to form the surface acoustic wave devices 10a and 10b that operate independently and form one device with two piezoelectric devices.

The container body 20 is composed of two substrates 21, 22 and a sealing member 23. Since one base (base) 21 has a flat plate shape in this embodiment,
Hereinafter, when only one of the bases is described, it will be referred to as a base 21.

The one base 21 is made of a flat plate-shaped insulating ceramic such as alumina. And base 2
A terminal electrode 24 for achieving electrical connection and mechanical connection of the printed wiring board is formed at one end of the terminal 1. In the embodiment, a plurality of terminal electrodes such as a terminal electrode for input / output signal potential and a ground terminal electrode are formed.

The terminal electrode 24 is formed from the inside of the container body 20 along the outer surface thereof, and extends over the surface of the base 21 constituting the container body 20, the end surface, and the back surface. Further, the conductor pattern extends from the terminal electrode 24 on the front surface side to the vicinity of the position where the composite surface acoustic wave element 10 is erected, and the tip portion thereof serves as a connection pad.

The other base 22 is made of a case-like insulating ceramic such as alumina. The base 22 is joined so as to cover the surface of the base 21, and a space 26 is formed inside the base 22 to accommodate the composite surface acoustic wave element 10.

Both of the bases 21 and 22 are the sealing member 2
Joined by 3. Generally, a ceramic substrate 2
The sealing of Nos. 1 and 22 is based on the sealing technology of the IC package and is sealed at the joint portion between the two via a low melting point glass material. When one base 21 is made of ceramic and the other base 22 has conductivity, one base 21
The metallized layer is formed on the substrate, the metal member for joining is interposed, and the joint is sealed by seam welding.

However, in the case of sealing with a low melting point glass, it is necessary to perform a heat treatment to the extent that the glass softens the entire container,
For example, when a piezoelectric substrate obtained by subjecting ceramics to polarization treatment is used, the Curie point may be exceeded, and an expensive heat treatment apparatus is required because the sealing temperature is high.

In the case of welding and sealing, the work of forming a metallized layer and interposing a metal member for joining is complicated.

On the other hand, in this embodiment, sealing is performed by using the sealing member 23 formed by applying and curing a resin bonding material such as epoxy resin, phenol resin, acrylic resin or the like.
This is because curing of the resin bonding material can be performed by curing at about 150 to 200 ° C., the characteristics of the piezoelectric substrate are not lost, the sealing process is simple, and the equipment required for sealing is small. Since the sealing method is inexpensive, and the temperature of the sealing process is low, restrictions on selection of conductive material, mechanical or electrical bonding material used for the composite surface acoustic wave element 10 in the container are relaxed. This is because an inexpensive material can be used.

Next, the housing structure in which the composite surface acoustic wave device 10 is housed in such a container 20 will be described.

One of the features of the present invention is that the composite surface acoustic wave element 10 is erected in the container 20 by utilizing the end surface 11d of the piezoelectric substrate 11.

That is, the piezoelectric substrate 11 is erected on the surface of the base 21 on one side, and is covered with the base 22 on the other side.
Therefore, both main surfaces of the piezoelectric substrate 11 are located on the side surfaces of the entire device, and it becomes possible for the first time to use both main surfaces of the piezoelectric substrate 11 for the operation of the surface acoustic wave.

First, the surface acoustic wave element 10 is erected at a predetermined position on one of the bases 21. That is, the terminal electrode 24 of the base 21 and the electrodes 12a and 12b of both main surfaces 11a and 11b of the piezoelectric substrate 11 are electrically connected to each other.

Next, the base 21 and the composite surface acoustic wave element 10
At the intersection with the lower end surface 11d of the conductive joint member 1,
Supply conductive adhesive such as solder or conductive resin that becomes 4
Apply.

If sufficient mechanical joining cannot be obtained only by hardening the conductive adhesive, a joining agent such as an insulating resin is used at the intersection of the piezoelectric substrate 11 and the one base 21. It may be added or applied to. Points to be noted when applying the conductive adhesive are that a short circuit does not occur between the different electrodes 12a and 12b and the terminal electrode 24, and that the conductive bonding member extends to the operating area of the surface acoustic wave of the piezoelectric substrate. 1
It is to prevent 4 from reaching.

Further, when the resonator 10a on the one main surface 11a side of the piezoelectric substrate 11 and the resonator 10b on the other main surface 11b side are connected as shown in the figure, the upper end surface 11c of the piezoelectric substrate 11 is connected. A conductive adhesive that becomes the conductive connecting member 13 is supplied and applied.

Points to note when applying the conductive adhesive are:
This is to prevent a short circuit from occurring between the different electrodes 12a and 12b, and to prevent the conductive connecting member 13 from reaching the operating area of the surface acoustic wave of the piezoelectric substrate.

Next, the conductive adhesive that becomes the conductive connecting member 13 and the conductive adhesive that becomes the conductive joining member 14 are commonly cured. As a result, the conductive bonding member 14 electrically and mechanically bonds the terminal electrode 24 on the side of the one base 21 to the electrodes 12a and 12b of the surface acoustic wave element 10, and at the same time, resonates with the resonator 10a. The child 10b is connected. In addition, when solder is used for the conductive joining member 14, and when a mechanical structure is used for the conductive connecting member 13, it is necessary to separately treat the conductive connecting member 13 and the difference in curing temperature of the resin. Alternatively, the curing process may be performed separately.

Next, as a sealing member 23, a part of the other base body 22, for example, a portion in contact with the one base 21 is provided.
An insulative resin bonding material is applied and primarily cured. Then, the other base 22 is brought into contact with the one base 21 so as to cover the surface acoustic wave element 10 and cured in this state to seal and integrate both bases 21 and 22. To do.

The surface mount type surface acoustic wave device 1 thus achieved is the piezoelectric substrate 1 of the composite surface acoustic wave element 10.
The surface acoustic waves can be used as the operating regions of the two main surfaces 11a and 11b, and the surface acoustic wave elements 10a and 10b can be formed on the respective main surfaces 11a and 11b.

Therefore, conventionally, the back surface side of the piezoelectric substrate was adhered to the substrate of the container body, and the back surface of the piezoelectric substrate became a dead space. However, in the present invention, this can be solved, and the piezoelectric substrate of the same size is doubled. The surface acoustic wave can secure an operating area. In other words, the shape of the piezoelectric substrate 11 can be miniaturized with respect to the number of the surface acoustic wave elements 10a and 10b formed, and can be simply miniaturized to, for example, 1/2.

Further, such a piezoelectric substrate 11 is erected inside the container body 20 by utilizing the lower end surface 11d of the piezoelectric substrate 11, and the electrodes 12a, 11a near the lower end surface 11d,
12b and the terminal electrode 24 of the one base 21 can be electrically connected and mechanically joined by the conductive joining member 14 obtained by curing a conductive adhesive such as solder or a conductive resin paste. It does not require fine wire bonding wires as in the past. For this reason, the accommodation space inside the container body can be made substantially equivalent to the shape of the piezoelectric substrate 11 (if it can be formed in a slight space around the piezoelectric substrate 11), and the shape of the container body can be reduced. can do.

The composite surface acoustic wave device 10 and the base 21 are also provided.
The means for electrically connecting to and becomes very simple.

In particular, since the composite surface acoustic wave element 10 is erected on one of the bases 21, the planar area of the container body 20 can be reduced, and as a surface mount type electronic component, The mounting area on the printed wiring board can be reduced.

Further, on the other hand, the base 21 may have a substantially flat plate shape, and it is not necessary to have a complicated structure, so that the cost is reduced together with the above-mentioned connecting means.

Further, both bases 21 constituting the container body 20,
As a sealing structure of 22, a sealing member 2 containing a resin as a main component
It is important to use 3.

This is because, inside the container body 20, the conductive connecting member 13 containing resin as a main component or the resin as a main component,
In order to use the conductive joining member 14 such as solder, in the conventional sealing structure for high temperature treatment (sealing structure using low melting point glass), the conductive connecting member 13 and the conductive joining member 14 are deteriorated. This is because it will end up. In addition, the sealing structure using seam welding, which is another sealing structure that has been widely used in the past, will increase the cost and should be avoided.

Sealing member 2 containing such a resin as a main component
It has been confirmed that even if 3 is used, the moisture resistance reliability is not deteriorated.

<Second Surface Acoustic Wave Device> Next, an embodiment of the second surface acoustic wave device according to the present invention will be described.

As shown in FIG. 4, a surface acoustic wave device 30 is provided.
Is a surface acoustic wave element 29 formed by forming an excitation electrode 33 forming a filter, a resonator, or the like on each of the two main surfaces of the piezoelectric substrate 34, and has a space 27 inside, and from the space 27 to the outer surface. It is accommodated in a package (container body) in which the terminal electrodes 32 are formed in a state of being aligned with. The package includes a base 31 and a package lid 39.

Here, the surface acoustic wave element 29 is shown in FIG.
As shown in (a), both principal surfaces 34a, 34 of the piezoelectric substrate 34
An excitation electrode 33 is formed on each of the b electrodes, and the terminal electrodes 32, 32 of the base 31 and the piezoelectric substrate 34 are arranged in a state where one main surface 34b of the piezoelectric substrate 34 faces the main surface 31a of the base 31. The excitation electrodes 33, 33 are connected via the electrode pad 35. Reference numeral 37 in the drawing denotes a bump for flip-chip connection, which will be described later.

As described above, in the surface acoustic wave device 30, the terminal electrodes 32 and 32 are formed on both main surfaces 31a and 31b of the package base (hereinafter, simply referred to as "base") 31 which constitutes the package (container body). , A piezoelectric substrate 34 provided on the base 31 and having excitation electrodes 33, 33 formed thereon. With one main surface 34b of the piezoelectric substrate 34 facing the main surface 31a of the base 31, The terminal electrode 32 is connected to the excitation electrodes 33, 33 of the piezoelectric substrate 34. That is, the electrode pads 35, 35 formed on the main surface 34a of the piezoelectric substrate 34 are connected to the terminal electrodes 32, 32 by wire bonding wires 36, 36, and are formed on one main surface 34b of the piezoelectric substrate 34. The electrode pads 35, 35 are connected to the terminal electrodes 32, 32 by flip chip bonding by conductive bumps 37.

By surrounding the bumps 37 with an adhesive 38 such as a thermosetting resin or a photosetting resin, the piezoelectric substrate 34 can be firmly fixed to the terminal electrodes 32, 32. .

Also with this second surface acoustic wave device, by forming surface acoustic wave electrodes such as excitation electrodes on both main surfaces of the piezoelectric substrate, the area of the surface acoustic wave element can be reduced to about half that of the conventional one. It is possible to reduce the size of the package, and the size of the package can be reduced accordingly. For example, a surface acoustic wave device such as a small surface acoustic wave filter can be provided.

Here, as the piezoelectric substrate 34, lithium niobate, lithium tantalate, and lithium tetraborate, which can cope with a high frequency of GHz order in this field, are very useful.

Further, the surface acoustic wave electrodes such as the excitation electrodes 33 formed on both surfaces of the piezoelectric substrate 34 are formed into surface mount type packages by using flip chip bonding and wire bonding on the respective surfaces of the electrical terminals of the package. Compact and easy electrical connection is possible.

Next, a manufacturing process of the surface acoustic wave device having the above structure will be described. First, the excitation electrode 33 and the like are patterned on one main surface of the piezoelectric substrate 34 by using photolithography, a thin film forming method, an etching method, or a lift-off method. That is, the main surface 3 of the piezoelectric substrate 34
A surface acoustic wave electrode such as the first excitation electrode 33 is formed on the surface 4a, and a surface acoustic wave electrode such as the second excitation electrode 33 is formed on the other main surface 34b by the same method.

Here, the alignment of the surface acoustic wave electrodes formed on both main surfaces of the piezoelectric substrate 34 can be easily performed using a marker or the like. In addition, the main surface of the piezoelectric substrate 34 on which the electrodes are previously formed is formed on the area where the electrode pads 35, 35 are patterned in order to prevent damage to the other main surface during electrode formation. It is also possible to provide.

After forming the surface acoustic wave electrodes on both main surfaces of the piezoelectric substrate 34 in this manner, metal bumps 37 are provided on the electrode pads 35 on the surface to be flip-chip bonded. For example, a ball bonder is used to form a gold ball.

After that, the surface acoustic wave element which has been cut into small pieces by dicing is mounted in the package to complete the surface acoustic wave device 30 shown in FIG.

That is, a conductive resin is used as the adhesive 38 on one side of the surface acoustic wave element facing the base 31 side, and the surface acoustic wave element and the package substrate are bonded by thermocompression bonding of the bumps 37 which are gold bumps. The base 31 is electrically connected and mechanically and firmly fixed. After that, the electrode pads 35, 35 on the other surface and the terminal electrodes 32, 32 provided on the package base 31 are electrically connected by wire bonding. After that, the package lid 39 and the package base 31 are connected and sealed by using a sealing member to complete a desired surface acoustic wave device such as a surface acoustic wave filter. In addition, this sealing is seam welding sealing,
Resin sealing, glass sealing and the like are preferably used.

Next, another embodiment will be described. The surface acoustic wave device 40 shown in FIG. 5 is manufactured as follows. That is, after the surface acoustic wave element 29 is completed similarly to the surface acoustic wave device 30, one surface of the surface acoustic wave element is bonded to the terminal electrodes 32, 32 of the package base 31 by thermocompression bonding of gold bumps. Make an electrical connection. Then, the side portions 34c, 34 of the surface acoustic wave element (piezoelectric substrate) are
The adhesive 42, 42 of a thermosetting adhesive or a photo-curing adhesive is injected into the gap between the c and the package inner side walls 41, 41 and cured. After that, the electrode pads 35 on the other surface of the piezoelectric substrate 34 and the inner terminal electrodes 43, 43 provided on the package inner side wall 41 are connected by wire bonding. After that, the surface acoustic wave device such as a desired surface acoustic wave filter is completed by sealing with a package sealing member in the same manner as the surface acoustic wave device 30. The package (container) is the package base 3
1, a package outer wall, a package lid 45, and the like. Also, 28 in the figure is a space. Also in this embodiment, the surface acoustic wave element 29 can be firmly fixed to the package base 31. Further, as in the surface acoustic wave device 30, by enclosing the adhesive around the bumps 37, it is possible to make the structure more robust.

In the above-described embodiment, the surface acoustic wave electrodes are formed on both main surfaces of the piezoelectric substrate to form the elements for generating the surface acoustic waves. Examples of this element include a surface acoustic wave resonator, a resonator type surface acoustic wave filter, and an IID.
T type surface acoustic wave filter, propagation type surface acoustic wave filter,
A band eliminator, a surface acoustic wave duplexer, etc. can be exemplified, and passive elements (resistors, capacitors, coils) used for characteristic adjustment and impedance matching of elements that generate surface acoustic waves on one principal surface or both principal surfaces. The electrode pattern may be formed.

For example, only electrodes for generating surface acoustic waves may be formed on one main surface side, and electrode patterns of passive elements may be formed on the other main surface side.

Further, an electrode for generating a surface acoustic wave and an electrode pattern of a passive element are arranged side by side on one main surface side,
On the other hand, an electrode for generating a surface acoustic wave may be formed on the main surface side.

Furthermore, electrodes for generating surface acoustic waves and electrode patterns of passive elements may be formed on both principal surfaces, respectively.

In particular, in the first surface acoustic wave device, the electrode formed on the one main surface side and the electrode on the other main surface side are connected via the conductive member 13 at the upper end surface 11c of the piezoelectric substrate. However, depending on the connection structure, a plurality of the conductive connection members 13 may be scattered, and the electrode formed on the one main surface side and the electrode on the other main surface side are not connected,
The surface acoustic wave elements on both principal surfaces may be operated independently.

The surface acoustic wave of the present invention includes Rayleigh waves and leaky waves.

[0086]

As described above, according to the first surface acoustic wave device of the present invention, the surface acoustic wave element is erected inside the container body and at the same time on both main surfaces of the piezoelectric substrate. Since the surface acoustic wave elements formed on each are connected to the terminal electrodes with a conductive adhesive, and since the surface acoustic wave elements are connected to each other with a conductive adhesive, compared to the prior art,
The surface acoustic wave operating area of the piezoelectric substrate is doubled, and as a result, the piezoelectric substrate can be downsized. Moreover, electrical connection is possible without using wire bonding thin wires, and the container itself can be downsized. As a result, the entire surface mount type surface acoustic wave device is downsized. At the same time, it is possible to provide a surface-mounting surface acoustic wave device in which the shape of the base body forming the container body is simplified and the connection structure between the base body and the surface acoustic wave element is also simplified.

In particular, according to the second surface acoustic wave device, the surface acoustic wave element has the excitation electrode formed on one main surface thereof by flip chip bonding and the excitation electrode formed on the other main surface thereof by wire bonding. Since the flip chip bonding is connected to the terminal electrodes and the conductive bumps are surrounded by the adhesive made of resin, the flip chip bonding can be downsized similarly to the first surface acoustic wave device. In addition, it is possible to easily realize the reduction in height, which is required for electronic components for mobile communication devices, and to easily design electrodes. In addition, since it can be made to have high strength especially against a lateral impact,
A highly reliable surface acoustic wave device can be provided. Further, particularly in a high frequency surface acoustic wave filter, the electrical resistance of the electrical connection portion greatly affects the characteristics such as loss, so connection with low resistance is essential, but the terminal electrode of the base and the piezoelectric substrate Since the excitation electrode formed on the main surface is adhered via the conductive bump, the connection can be made easily and with low resistance, and a highly reliable surface acoustic wave device can be provided.

[Brief description of drawings]

FIG. 1 is an external perspective view of a first surface acoustic wave device according to the present invention.

FIG. 2 is a sectional view of a first surface acoustic wave device according to the present invention.

FIG. 3 shows a first surface acoustic wave device according to the present invention,
It is a schematic diagram in the state where the other substrate was omitted.

FIG. 4 is a sectional view of a second surface acoustic wave device according to the present invention.

FIG. 5 is a sectional view of a second surface acoustic wave device according to the present invention.

6A is a cross-sectional view of a piezoelectric substrate having excitation electrodes and the like formed on both main surfaces, and FIG. 6B is a plan view thereof.

FIG. 7 is a plan view of a piezoelectric substrate on which conventional excitation electrodes and the like are formed.

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

[Explanation of symbols]

1: Surface mount type surface acoustic wave device, 10, 29: Surface acoustic wave element, 11, 34: Piezoelectric substrate, 11a: One main surface of the piezoelectric substrate, 11b: The other main surface of the piezoelectric substrate, 11c: Top of the piezoelectric substrate Side end face, 11d: Lower side end face of the piezoelectric substrate, 12
a: electrode, 12b: electrode, 13: conductive connecting member, 1
4: conductive bonding member, 20: container body, 21: one base body (base), 22: other base body, 23: sealing member, 24:
Terminal electrode, 26, 27, 28: Space, 31: Package base, 33: Excitation electrode, 37: Bump, 38, 42: Adhesive

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-294110 (JP, A) JP-A-6-37582 (JP, A) JP-A-59-169218 (JP, A) JP-A-9- 181562 (JP, A) Actual opening 60-95733 (JP, U) Actual opening 58-37222 (JP, U) Actual opening Sho 64-37132 (JP, U) Actual opening Flat 6-48226 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H03H 9/25

Claims (2)

(57) [Claims] 1. A container in which a surface acoustic wave element having excitation electrodes formed on both main surfaces of a piezoelectric substrate has a space inside and a terminal electrode is formed along the outer surface from the space. A surface acoustic wave device housed inside a body, wherein the surface acoustic wave element is erected inside the container body, and the surface acoustic wave is formed on each of the two main surfaces of the piezoelectric substrate. A surface acoustic wave device, wherein a wave element is connected to the terminal electrode with a conductive adhesive, and the surface acoustic wave elements are connected with each other with a conductive adhesive. 2. A container in which a surface acoustic wave element formed by forming excitation electrodes on both main surfaces of a piezoelectric substrate has a space inside and a terminal electrode is formed along the outer surface from the space. A surface acoustic wave device which is housed inside a body, wherein the surface acoustic wave element has an excitation electrode formed on one main surface by flip chip bonding and an excitation electrode formed on the other main surface by wire bonding. The surface acoustic wave device is characterized in that the flip chip bonding is connected to the terminal electrodes respectively, and the conductive bumps are surrounded by an adhesive made of resin.