Surface acoustic wave device and method of manufacture thereof

Details Surface acoustic wave device and method of manufacture thereof Surface acoustic wave device and method of manufacture thereof

2001-11-21

2003-03-18

Dougherty, Thomas M. (Department: 2834)

Electrical generator or motor structure

Non-dynamoelectric

Piezoelectric elements and devices

C310S31300R, C310S344000

Reexamination Certificate

active

06534901

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface acoustic wave device for use in wireless communications equipment and the like and method of manufacture thereof.
BACKGROUND OF THE TECHNOLOGY
FIG. 23
is a cross-sectional view of a conventional surface acoustic wave device (hereinafter SAW device). Referring to
FIG. 23
, a description will be given below on the method of manufacture of the conventional SAW device.
First, interdigital transducer electrodes (IDT electrodes)
101
and connection electrodes
102
are formed by forming vacuum deposited aluminum film on a disk (wafer) of piezoelectric material followed by exposing with a pattern of predetermined configuration and developing. Subsequently, acoustic absorbers
103
are formed by coating a silicone resin on both sides of the IDT electrodes
101
by screen printing and heat treatment. In this way, a number of surface acoustic wave elements
105
(SAW elements) are collectively formed on the wafer. Subsequently, the wafer is diced into individual SAW elements
105
.
Next, a SAW element
105
is secured with adhesive
108
in a package
107
having external terminals
106
, and the external terminals
106
and connection electrodes
102
are electrically connected with thin metal wires
109
. Subsequently, opening of the package
107
is sealed with a lid
110
.
When the acoustic absorbers
103
are formed by screen printing in this manner, the dimensional accuracy is poor and also their cross sections become dome-like due to drips caused by flow of the resin, thus suffering from the upper surfaces becoming curved and difficulty in forming with a uniform height.
Furthermore, when mounting the SAW element
105
in the package
107
, as the SAW element
105
is transferred by sucking its surface with a vacuum chuck, there is a difficulty in sucking because the top surfaces of the acoustic absorbers
103
are curved and their heights are different. In addition, piezoelectric substrate
100
may incline relative to the bottom surface of the package
107
thus presenting a possibility of causing mounting failure.
FIG. 24
is a cross-sectional view of another conventional SAW device. While thin metal wires
109
connect the connection electrodes
102
and the external terminals
106
in the conventional SAW device of
FIG. 23
, in another conventional SAW device shown in
FIG. 24
, projecting electrodes
111
(bumps) make the connection.
In this case, too, there is a possibility of causing connection failure when the heights of the acoustic absorbers
103
are non-uniform and are greater than the bumps
111
.
DISCLOSURE OF THE INVENTION
The present invention addresses the above issues and aims at providing a SAW device that can prevent mounting failure when mounting a SAW element in a package.
In order to attain this object, the SAW device of the present invention comprises a package having an external terminal, a SAW element housed in the package, and a lid for sealing opening of the package, wherein the SAW element further comprises on the surface of a piezoelectric substrate at least an IDT electrode, a connection electrode electrically connected to the IDT electrode, and an acoustic absorber formed on the outside of the IDT electrode, that is, on an end portion of the piezoelectric substrate, in a manner such that its top surface is parallel to the main surface of the piezoelectric substrate. As the surface of the acoustic absorber is parallel to the main surface of the piezoelectric substrate in this way, and as the top surface of the acoustic absorber is a plane, it is easy to suck the SAW element with a vacuum chuck when mounting in a package and it is possible to securely mount it at a predetermined position of the package.


REFERENCES:
patent: 4931752 (1990-06-01), Bray et al.
patent: 5215546 (1993-06-01), Cho et al.
patent: 5469170 (1995-11-01), Mariani
patent: 5594979 (1997-01-01), Borchelt et al.
patent: 57-186819 (1982-11-01), None
patent: 58-92117 (1983-06-01), None
patent: 59-74719 (1984-04-01), None
patent: 63-178615 (1988-07-01), None
patent: 2-174412 (1990-07-01), None
patent: 4-258009 (1992-09-01), None
patent: 4-275714 (1992-10-01), None
patent: 8-97673 (1996-04-01), None
patent: 8-111629 (1996-04-01), None
patent: 8-307197 (1996-11-01), None
patent: 11-251867 (1999-09-01), None
patent: 2000-252787 (2000-09-01), None

Affiliated with

Also associated with

Rating

Surface acoustic wave device and method of manufacture thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Surface acoustic wave device and method of manufacture thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface acoustic wave device and method of manufacture thereof will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3078794