JP2000040939A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a surface acoustic wave device high function and compound and simultaneously to miniaturize it by providing the functioning part and terminal parts of the surface acoustic wave device on the surface and rear face of a piezoelectric substrate and providing a gap between the rear face of the substrate and a package. SOLUTION: Functioning part 3a and 3b, which respectively consists of one or more pairs of input-output transducers and input-output signal terminals and ground terminals 4a and 4b, are formed on the surface side and rear side of a surface acoustic wave element (SAW chip) 1 consisting of a piezoelectric substrate. The terminals 4b on the rear side of the chip 1 are electrically connected to a package conducting part 9 with a bump 10. The terminals 4a on the surface side of the chip 1 are electrically connected to the part 9 with a bonding wire 7 through a bonding pad 8. A gap corresponding to the height of the bump 10 is formed between the rear side of the chip 1 and a package 2 main body by the bump 10. The part 3b is formed in the gap.

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 used for, for example, a high-frequency circuit of a mobile communication device.

[0002]

2. Description of the Related Art As a conventional surface acoustic wave device, for example,
There is an apparatus disclosed in JP-A-7-212181. FIG. 4 is a diagram showing a vertical cross-sectional configuration of this conventional device. The device shown in FIG. 1 includes a surface acoustic wave element 1 (hereinafter referred to as SA).
The SAW chip 1 includes a surface acoustic wave function unit 3 and an input / output signal terminal / ground terminal 4. This SAW chip 1 is mechanically fixed to the package 2 by an adhesive 5. This conventional device further includes a cap 6 for hermetically sealing the opening of the package 2 by bonding or bonding.

The input / output signal terminals of the SAW chip 1
The grounding terminal 4 is electrically connected to the package conductive portion 9 through bonding pads 8 provided near both ends of the package 2 by bonding wires (bonding wires) 7 made of ultrafine wires such as gold or aluminum. ing.

[0004]

However, the conventional surface acoustic wave device having the above-mentioned structure has the same characteristics or completely different characteristics in the same package because of its high functionality and compositeness. If more than one SAW chip 1 is to be accommodated, the area and volume of the package 2 will increase as the number of SAW chips 1 increases. Therefore, when this type of surface acoustic wave device is used in, for example, a mobile communication device, there is a problem that it is not possible to meet the demand for downsizing of the surface acoustic wave device accompanying the downsizing of the mobile communication device.

A surface acoustic wave function unit 3 having equivalent characteristics or completely different characteristics is provided on a single SAW chip 1.
When two or more are formed, the area of the SAW chip 1 increases according to the number of the functional units, and the same problem as described above occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface acoustic wave device capable of achieving a high-performance and complex surface acoustic wave device, and at the same time, capable of being downsized. It is to be.

[0007]

According to the present invention, there is provided a surface acoustic wave device comprising at least a pair of functional parts and terminals formed on a piezoelectric substrate in a package. A surface acoustic wave device having a configuration in which the package is hermetically sealed with a cap, wherein the functional unit and the terminal unit are provided on the front and back surfaces of the piezoelectric substrate,
Each terminal on the surface of this piezoelectric substrate is connected by a connecting wire.
By electrically connecting to a pad provided inside the package, and forming a bump on each terminal on the back surface of the piezoelectric substrate, a gap having a predetermined height is formed between the surface acoustic wave element and the package. And a surface acoustic wave device in which each terminal on the back surface of the piezoelectric substrate is electrically connected to a conductive portion provided inside the package via the bump.

Another invention has a configuration in which a surface acoustic wave element having at least one or more functional units and terminals formed on a piezoelectric substrate is housed in a package, and the package is hermetically sealed with a cap. In the surface acoustic wave device, the two surface acoustic wave elements are formed in a two-stage configuration of an upper stage and a lower stage, and the functional portion and the terminal portion are provided on one surface of each of the piezoelectric substrates located above and below, and further, By forming a bump on each, between the two surface acoustic wave elements, and between the surface acoustic wave element located at the lower stage and the package to provide a gap of a predetermined height, these bumps, A surface acoustic wave device electrically connected to a pad or a conductive portion provided inside the package.

Still another aspect of the present invention is directed to a configuration in which a surface acoustic wave element having at least one pair of functional units and terminals formed on a piezoelectric substrate is housed in a package, and the package is hermetically sealed with a cap. In the surface acoustic wave device having the above, the functional portion and the terminal portion are provided on the first surface of each of the two piezoelectric substrates, and the second surfaces of the two piezoelectric substrates are bonded to each other with an adhesive. And
Further, of the two piezoelectric substrates, each terminal on the first surface of one of the piezoelectric substrates is electrically connected to a pad provided inside the package by a coupling line,
A bump is formed on each of the terminal portions on the second surface of the other piezoelectric substrate, and a predetermined space is formed between the package and the entire surface acoustic wave element in which the two piezoelectric substrates are bonded to each other. These bumps, with a gap of height
A surface acoustic wave device electrically connected to a conductive portion provided inside the package.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Embodiment 1 FIG. First, a first embodiment according to the present invention will be described. FIG. 1 is a longitudinal sectional view showing the configuration of the surface acoustic wave device according to Embodiment 1 of the present invention. In this figure, the same or corresponding components as those of the above-described conventional surface acoustic wave device shown in FIG. 4 are denoted by the same reference numerals, and the detailed description thereof will be omitted.

In the surface acoustic wave device shown in FIG. 1, functional units 3a and 3b each composed of one or more pairs of input / output transducers and input / output signal terminals are provided on the front and back sides of a SAW chip 1 made of a piezoelectric substrate.・ Ground terminal 4
a and 4b are formed. The SAW chip 1 itself is mechanically fixed to the package 2 by bumps 10 provided on the back side. Further, a cap 6 for hermetically sealing the opening of the package 2 by bonding or bonding is provided.

The input / output signal terminal / ground terminal 4b on the back side of the SAW chip 1 is electrically connected to the package conductive portion 9 by the bump 10 described above. These bumps 10 are connected to the package conductive part 9 by a flip chip method. The input / output signal terminals / ground terminals 4 a on the front surface of the SAW chip 1 are connected to the bonding pads 8 on the package 2 by bonding wires 7. Through,
It is electrically connected to the package conductive part 9.

That is, in the surface acoustic wave device according to the present embodiment, the bump 10 provided on the back surface side of the SAW chip 1 is located on the bottom surface of the package 2, and the SAW chip 1 Is mounted. Then, the SAW chip 1 is formed by the bumps 10.
A gap corresponding to the height of the bump 10 is formed between the back side of the package 2 and the body of the package 2. In other words, the surface acoustic wave device has a structure in which a surface acoustic wave function portion 3b is formed on the back surface side of the SAW chip 1 by utilizing a gap provided between the chip and the package.

Incidentally, an impedance matching pattern may be provided on the surface of the SAW chip 1 on the side connecting the input / output signal terminal / ground terminal (input terminal or output terminal) on each surface.

As described above, according to the present embodiment, a bump is provided on the bottom surface of the SAW chip, and the SAW chip is mounted on the bump. By forming the surface acoustic wave function part on the back side of the SAW chip using the gap with the package body of the device, the function part can be formed not only on the front side but also on the back side of the SAW chip. A small and high-performance surface acoustic wave device that effectively uses both sides of the SAW chip can be obtained.

Embodiment 2 Hereinafter, Embodiment 2 of the present invention will be described. FIG. 2 is a longitudinal sectional view showing the configuration of the surface acoustic wave device according to Embodiment 2 of the present invention. In the figure, the same components as those of the surface acoustic wave device according to Embodiment 1 shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted here.

As shown in FIG. 2, in the surface acoustic wave device according to the present embodiment, the SAW chips 1a and 1b have a two-tiered structure, and each of the SAW chips 1a and 1b has a functional unit 3a. , 3b and input / output signal terminal / ground terminal 4
a, 4b are formed. These SAW chips 1a,
1b, the SAW chip 1a is mechanically fixed to the package 2 by a bump 10a provided on the back surface, and the input / output signal terminal / ground terminal 4a is
Of the package conductive portion 9 through the bonding pad 8 of FIG.
Is electrically connected to

In the lower SAW chip 1b, the input / output signal terminal / ground terminal 4b is connected to the upper SA SA chip.
As with the W chip, it is mechanically fixed to the package 2 by a bump 10b provided on the bottom surface and is electrically connected to the package conductor 9. The opening of the package 2 is hermetically sealed by bonding or joining the cap 6.

As described above, according to the surface acoustic wave device of the present embodiment, the SAW chips are formed in two stages, upper and lower, each of which is mechanically fixed to the package by a bump, and A plurality of SAW chips are efficiently arranged in a limited space inside the package by being electrically connected to the conductive portion of the package via the input / output signal terminal / ground terminal formed above. It is possible to obtain a small and high-performance surface acoustic wave device.

Embodiment 3 Hereinafter, Embodiment 3 of the present invention will be described. FIG. 3 is a longitudinal sectional view showing the configuration of the surface acoustic wave device according to Embodiment 3 of the present invention. Also in this figure, the same components as those of the surface acoustic wave device according to Embodiment 1 shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted here.

The surface acoustic wave device according to the present embodiment shown in FIG. 3 has a configuration in which two SAW chips 1a and 1b are bonded back to back with an adhesive 5. On the SAW chip 1a, a functional unit 3a and an input / output signal terminal / ground terminal 4a are formed. The SAW chip 1b located below the SAW chip 1a is mechanically attached to the package 2 by bumps 10. Fixed. That is, two SAs bonded back to back
The W chips 1a and 1b are fixed to the package 2 by bumps 10.

The input / output signal terminal / ground terminal 4a of the SAW chip 1a is electrically connected to the package conductive section 9 via the bonding pad 8 of the package 2 by the bonding wire 7. Also, the SAW chip 1b
Are electrically connected to the package conductive portion 9 via bumps 10 provided on the bottom surface of the package 2.
In this SAW chip 1b, the functional unit 3
b is the SAW chip 1b as in the first and second embodiments.
The surface acoustic wave function section 3b is formed on the back side of the SAW chip 1b by utilizing a gap provided between the back side of the package 2 and the body of the package 2.

In this embodiment, a cap 6 is also provided at the opening of the package 2 to hermetically seal the opening by bonding or bonding.

As described above, according to the surface acoustic wave device of the present embodiment, two SAs are formed by the adhesive.
By bonding the surfaces of the W chip having no functional part to each other and mechanically fixing the bonded chip to the package by bumps, the W chip is small and high in size, as in the first and second embodiments. A functional surface acoustic wave device is obtained.

In the surface acoustic wave device according to each of the above-described embodiments, for example, the functional unit 3a formed on the front surface side of the SAW chip 1 and the functional unit formed on the back surface side of the chip in the first embodiment The electrical characteristics of 3b may be completely the same or may have completely different and different electrical characteristics.

For example, a mobile communication device, especially a mobile phone,
In a cordless telephone or the like, at least one surface acoustic wave device described above is used for a reception circuit unit, a transmission circuit unit, and the like, and the electrical characteristics required for each of these circuit units are different.

Therefore, in such a receiving circuit section and a transmitting circuit section, a functional section necessary for the receiving circuit section may be formed on both the front side and the rear side of the SAW chip, and a function necessary for the transmitting circuit section may be formed. A part may be formed. On the other hand, a functional unit required for the receiving circuit unit may be formed on the front side of the SAW chip, and a functional unit required for the transmitting circuit unit may be formed on the back side. Further, these may be formed in a reversed form.

Further, the mobile phone and the like, the communication method
There are various standards with different standards. For example, in Japan, PD
There are C system and PHS system. In Europe, GSM and DHS
There are CS system, AMPS system and PCS system in the United States. Since the electrical characteristics required for the receiving circuit unit and the transmitting circuit unit in each of the above methods are different, SA
The functional units required for the above-described different communication systems and standards may be formed on the functional units on the front side and the back side of the W chip.

Further, the surface acoustic wave device according to the present invention is not limited to the above embodiments, and it goes without saying that Embodiments 1 to 3 may be appropriately combined. Further, the number of SAW chips housed in the same package is not limited to two as in the second and third embodiments.
More than the above number of chips may be mounted in the package without departing from the purpose of reducing the size of the device.

[0030]

As described above, according to the first aspect, the functional portion and the terminal portion are provided on the front and back surfaces of the piezoelectric substrate.
Each terminal on the surface of this piezoelectric substrate is connected by a connecting wire.
It is electrically connected to pads provided inside the package, and bumps are formed on the respective terminals on the back surface of the piezoelectric substrate to provide a predetermined gap between the surface acoustic wave element and the package. Each terminal on the back surface of the piezoelectric substrate is electrically connected to a conductive portion provided inside the package via a bump, so that both sides of the SAW chip can be effectively used to achieve a compact and high-performance device. A functional surface acoustic wave device can be obtained.

According to the second aspect of the present invention, the two surface acoustic wave elements are formed in two stages, an upper stage and a lower stage, and a functional portion and a terminal portion are provided on one surface of each of the piezoelectric substrates located above and below. A bump is formed at each of these terminal portions, a predetermined height gap is provided between the two surface acoustic wave elements and between the surface acoustic wave element located at the lower stage and the package, and these bumps are formed in the package. A small and high-performance surface acoustic wave device can be realized by electrically connecting to a pad or a conductive portion provided inside the device.

According to the third aspect of the present invention, the functional portion and the terminal portion are provided on the first surface of each of the two piezoelectric substrates, and the second surfaces of each of the two piezoelectric substrates are bonded to each other. Each of the terminals on the first surface of one of the two piezoelectric substrates is electrically connected to a pad provided inside the package by a bonding wire. A bump is formed on each terminal portion on the second surface of the other piezoelectric substrate, and a predetermined surface is provided between the entire surface acoustic wave element in which these two piezoelectric substrates are bonded to each other and the package. By providing a height gap and electrically connecting these bumps to a conductive portion provided inside the package, a small and high-performance surface acoustic wave device can be realized.

By connecting the bump to a pad or a conductive portion provided inside the package by a flip chip method, it is possible to maintain the mechanical strength as well as the ease of connection.

By electrically connecting the input terminals and the output terminals included in the terminal portion to each other inside the package, the number of signal pins of the surface acoustic wave device and the number of wirings outside the device are reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a longitudinal sectional configuration of a surface acoustic wave device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a longitudinal sectional configuration of a surface acoustic wave device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a longitudinal sectional configuration of a surface acoustic wave device according to a third embodiment of the present invention.

FIG. 4 is a view showing a longitudinal section of a conventional surface acoustic wave device.

[Explanation of symbols]

1, 1a, 1b: surface acoustic wave element (SAW chip), 2
... Package, 3,3a, 3b ... Surface acoustic wave function part,
4, 4a, 4b: input / output signal terminal / ground terminal, 5: adhesive, 6: cap, 7: bonding wire, 8: bonding pad, 9: package conductive part, 10, 10
a, 10b ... bump

Claims (5)

[Claims] 1. A surface acoustic wave having a structure in which a surface acoustic wave element having at least one pair of functional parts and terminals formed on a piezoelectric substrate is housed in a package, and the package is hermetically sealed with a cap. In the apparatus, the functional unit and the terminal unit are provided on the front and back surfaces of the piezoelectric substrate, and each terminal unit on the front surface of the piezoelectric substrate is electrically connected to a pad provided inside the package by a bonding wire. A bump is formed on each terminal on the back surface of the piezoelectric substrate to provide a gap of a predetermined height between the surface acoustic wave element and the package. A surface acoustic wave device, wherein each terminal portion on the back surface of the substrate is electrically connected to a conductive portion provided inside the package. 2. A surface acoustic wave having a configuration in which a surface acoustic wave element having at least one pair of functional parts and terminals formed on a piezoelectric substrate is housed in a package, and the package is hermetically sealed with a cap. In the apparatus, the two surface acoustic wave elements are formed in two stages of an upper stage and a lower stage, and the functional unit and the terminal unit are provided on one surface of each of the piezoelectric substrates located above and below, and a bump is provided on each of the terminal units. To provide a gap of a predetermined height between the two surface acoustic wave elements, and between the surface acoustic wave element located at the lower level and the package, and to provide these bumps with A surface acoustic wave device electrically connected to a pad or a conductive portion provided inside. 3. A surface acoustic wave having a configuration in which a surface acoustic wave element comprising at least one pair of functional units and terminals on a piezoelectric substrate is housed in a package, and the package is hermetically sealed with a cap. In the apparatus, the functional portion and the terminal portion are provided on the first surface of each of the two piezoelectric substrates, and the second surfaces of each of the two piezoelectric substrates are bonded to each other with an adhesive. Of the two piezoelectric substrates, each terminal on the first surface of one of the piezoelectric substrates is electrically connected to a pad provided inside the package by a bonding wire, and the other piezoelectric substrate is connected to the other piezoelectric substrate. A bump having a predetermined height is formed between the package and the entire surface acoustic wave device in which the two piezoelectric substrates are bonded to each other by forming a bump on each terminal portion on the second surface of the elastic substrate. Establish this Luo bump, a surface acoustic wave device characterized by being electrically connected to the conductive portion provided on the interior of the package. 4. The surface acoustic wave device according to claim 1, wherein the bump is connected to a pad or a conductive portion provided inside the package by a flip chip method. 5. The device according to claim 1, wherein the terminal portion includes an input terminal and an output terminal, and the input terminal and the output terminal are electrically connected to each other inside the package. A surface acoustic wave device according to any one of claims 1 to 4.