JPH10107575A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave device in which a SAW element is made small resulting in making the entire device small and whose cost is reduced. SOLUTION: A SAW element 10 is provided with a rectangular surface acoustic wave substrate 11, and two IDT electrodes formed on the surface acoustic wave substrate 11 and reflector electrodes 13 formed to the outside of the IDT electrodes 12 in the surface acoustic wave propagation direction are provided are locally provided to one side perpendicularly with respect to the surface acoustic wave propagation direction. Then all bump electrodes 15 formed to a tip of each leadout electrode 14 are provided to one side of the IDT electrodes 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface acoustic wave device, and more particularly, to a surface acoustic wave device in which a SAW element and a base substrate are connected by solder bumps.

[0002]

2. Description of the Related Art FIG. 4 is a plan view showing an example of a conventional SAW element mounted on a base substrate by solder bump connection.

The SAW element 10 has a surface acoustic wave substrate 11, two IDT electrodes 12 at a substantially central portion on the upper surface of the surface acoustic wave substrate 11, a reflector electrode 13 outside these IDT electrodes 12, and each IDT electrode. Two extraction electrodes 14 are respectively extracted from the electrodes 12, and a circular bump electrode 15 is formed at the tip of each extraction electrode 14.

[0006] Two bump electrodes 15 are formed for each IDT electrode 12, and the two bump electrodes 1 are formed.
5 is the IDT electrode 12 with the IDT electrode 12 interposed therebetween.
Are located on both sides. Also, each bump electrode 15
In order not to affect the characteristics of the surface acoustic wave device, the IDT
It is formed at a predetermined distance from the electrode 12.

As shown in FIG. 5, the SAW element 10 shown in FIG. 4 is of a face-down type, that is, with the surface on which various electrodes are formed facing down, each bump electrode 15 of the SAW element 10 and Is electrically and mechanically connected to the electrode lands 22 formed by the solder bumps 51,
It is mounted on a base substrate 20. Further, the metal cap 30 having an open surface on one side is formed by soldering the opening and the square annular bonding land 21 formed on the peripheral portion of the base substrate 20 to the solder 5.
2, the SAW element 10 is attached to the base substrate 20 with the metal cap 3
A surface acoustic wave device is sealed in a package made of zero.

That is, the plurality of electrode lands 22 formed on the base substrate 20 correspond to the bump electrodes 1 of the SAW element 10.
5 are formed.

[0007]

However, in the above-described conventional surface acoustic wave device, the extraction electrode 14 and the bump electrode 15 are disposed on both sides of the IDT electrode 12 with the IDT electrode 12 interposed therebetween. Space is required on both sides for arranging the bump electrodes 15, and SA
It was difficult to reduce the size of the W element 10. Therefore, the size of the base substrate 20 cannot be reduced, and it is difficult to reduce the size of the surface acoustic wave device.

Accordingly, an object of the present invention is to provide a surface acoustic wave device capable of reducing the size of a SAW element, thereby reducing the size of the SAW element, and reducing the cost. .

[0009]

According to a first aspect of the present invention, an IDT electrode, a plurality of extraction electrodes extracted from the IDT electrode and a tip of each extraction electrode are provided on a surface acoustic wave substrate. In a surface acoustic wave device, a SAW element having a bump electrode formed on a portion thereof is mounted on a base substrate having an electrode land formed on a surface thereof by solder bump connection between the bump electrode and the electrode land. All the bump electrodes are formed on one side of the IDT electrode.

According to the above configuration, all the bump electrodes of the SAW element are formed on one side of the IDT electrode, and the space on the side opposite to the side on which the bump electrodes are formed can be reduced. The base substrate on which the SAW element is mounted and the metal cap for sealing can also be reduced in size according to the dimensions of the SAW element, and the overall surface acoustic wave device can be reduced in size. .

Further, by reducing the size of the SAW element, the number of SAW elements to be removed from the surface wave motherboard (wafer) increases, and the cost of the SAW element can be reduced. Similarly, since the base substrate and the metal cap can be made smaller, the material cost can be reduced and the cost can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings showing embodiments thereof.

FIGS. 1 and 2 show the structure of a surface acoustic wave device according to one embodiment of the present invention. FIG. 1 is a plan view of a SAW element, and FIG. 2 is a sectional view of a surface acoustic wave device. In the following drawings, the same or corresponding parts as those of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

SA constituting the surface acoustic wave device of this embodiment
In the W element 10, as shown in FIG. 1, two IDT electrodes 12 formed on a rectangular surface wave substrate 11 and a reflector electrode 13 formed outside the IDT electrode 12 in the surface wave propagation direction are formed by surface acoustic waves. It is provided on one side in the direction perpendicular to the propagation direction. All of the bump electrodes 15 formed at the tip of each extraction electrode 14 are provided on the other side of the IDT electrode 12 in the direction perpendicular to the surface acoustic wave propagation direction.

Note that two IDT electrodes 12 correspond to one IDT electrode 12.
One of the bump electrodes 15 is for input / output, and the other is for ground.

In the surface acoustic wave device of this embodiment, as shown in FIG. 2, the SAW 10 and the base substrate 20 are arranged so that the surface on which each bump electrode 15 is formed and the surface on which each electrode land 22 is formed are opposed to each other. The SAW element 10 is connected and fixed to the base substrate 20 by soldering the electrode 15 and the electrode lands 22 with the solder bumps 51, respectively. That is, the plurality (four) of the electrode lands 22 formed on the base substrate 20 are formed at positions corresponding to the respective bump electrodes 15 of the SAW element 10.

The metal cap 30 is soldered to the base substrate 20 by solder 52 on a bonding land 21 formed on the periphery of the base substrate 20, so that the SAW element 10 is formed in a package comprising the base substrate 20 and the metal cap 30. Is sealed.

In the surface acoustic wave device of this embodiment, S
All bump electrodes 15 of AW element 10 are IDT electrodes 12
Of the bump electrode 15 and the ID
There is no need to provide a space on the opposite side of the T electrode 12 for forming the bump electrode 15 which was required in the conventional configuration. In other words, the space of the IDT electrode on the side opposite to the side on which the bump electrode 15 is formed can be reduced. The SAW element 10
Substrate 20 on which is mounted and metal cap 3 for sealing
Also, the size 0 is used in accordance with the size of the SAW element 10. Therefore, the entire surface acoustic wave device of the present embodiment is smaller than the conventional one.

Further, the size of the SAW element 10 is reduced, and the number of the SAW elements 10 taken from the surface wave motherboard (wafer) is increased.
The material cost of the W element 10 is reduced, and the cost is reduced. Similarly, the base substrate 10 and the metal cap 30
Is also downsized, so that material costs are reduced and costs are reduced.

In the above embodiment, the SAW element in which two IDT electrodes are formed on the surface acoustic wave substrate has been described. However, the present invention is not limited to this. For example, as shown in FIG. The present invention can also be applied to a surface acoustic wave device using a SAW element having one IDT electrode formed thereon or a SAW element having three or more IDT electrodes formed on a surface acoustic wave substrate.

Further, in the above embodiment, the SAW element in which the reflector electrode is formed on both sides of the IDT electrode has been described. However, the SAW device using the end face reflection type SAW element without the reflector electrode is provided. Is also good.

[0022]

As described above, according to the surface acoustic wave device of the present invention, all the bump electrodes of the SAW element are formed on one side of the IDT electrode, and the bump electrode formation side is sandwiched between the IDT electrodes. Since the space on the opposite side can be reduced, the size of the SAW element can be reduced, and the base substrate on which the SAW element is mounted and the metal cap for sealing are also reduced in size according to the dimensions of the SAW element. Therefore, the size of the entire surface acoustic wave device can be reduced.

Further, by reducing the size of the SAW element, the number of SAW elements that can be removed from the surface wave motherboard (wafer) increases, and the cost of the SAW element can be reduced. Similarly, since the base substrate and the metal cap can be made smaller, the material cost of the base substrate and the metal cap can be reduced, and the cost can be reduced.

Therefore, according to the present invention, a small and inexpensive surface acoustic wave device can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a SAW element according to one embodiment of the present invention.

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

FIG. 3 is a plan view of a SAW element according to another embodiment of the present invention.

FIG. 4 is a plan view of a conventional SAW element.

FIG. 5 is a sectional view of a conventional surface acoustic wave device.

[Explanation of symbols]

 Reference Signs List 10 SAW element 11 Surface acoustic wave substrate 12 IDT electrode 15 Bump electrode 20 Base substrate 22 Electrode land 30 Metal cap

Claims (1)

[Claims] 1. A SAW element having an IDT electrode on a surface acoustic wave substrate, a plurality of extraction electrodes extracted from the IDT electrode, and a bump electrode formed at the tip of each extraction electrode, and an electrode land formed on the surface. In a surface acoustic wave device mounted by connecting the bump electrodes and the electrode lands to a base substrate by solder bump connection, all the bump electrodes are formed on one side of the IDT electrodes. Surface acoustic wave device.