Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2002-02-06
2004-05-11
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S344000
Reexamination Certificate
active
06734605
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a surface acoustic wave device in which a surface acoustic wave element and an electronic component that drive controls the surface acoustic wave element are packaged.
2. Description of Related Art
Recently, surface acoustic wave devices (hereinafter referred to as “SAW (surface acoustic wave) devices”) have been used as resonators or bandpass filters, etc. in electronic components and communication components of mobile telephones and TV receivers, etc.
FIG. 8
is a schematic showing an example of a related art SAW device
1
. The SAW device
1
is described with reference to FIG.
8
.
The SAW device
1
of
FIG. 8
has a substrate
2
, a cover
3
, an electronic component
5
formed of IC chips, etc. and a SAW element
6
, and other elements. A hollow component
2
a
is formed in the substrate
2
. The electronic component
5
and the SAW element
6
are mounted in the hollow component
2
a
, e.g., with an epoxy adhesive. The cover
3
is arranged on the opening of the hollow component
2
a
and is joined to the substrate
2
with a sealant or by seam welding. Therefore, the electronic component
5
and the SAW element
6
are in a hermetically sealed state via the substrate
2
and the cover
3
.
The SAW element
6
and the electronic component
5
, such as semiconductor chips that drive control the SAW element, are arranged side by side in the hollow component
2
a
. Printed wirings
4
of a predetermined pattern are formed at the bottom of the substrate
2
, and the electronic component
5
and the SAW element
6
are electrically connected to the printed wirings
4
, e.g., by wire bonding, etc. respectively, thereby electrically connecting the electronic component
5
and the SAW element
6
.
FIGS.
9
(A)-
9
(E) are perspective views showing steps of an exemplary related art manufacturing method of a SAW device. The manufacturing method of the SAW device is described with reference to FIG.
9
.
First, as shown in FIG.
9
(A), printed wirings
4
are formed in a predetermined pattern at the bottom of a hollow component
2
a
in a substrate
2
.
Then, as shown in FIG.
9
(B), an electronic component
5
is mounted at the bottom and electrically connected to the printed wirings
4
, e.g., by wire bonding, etc.
Subsequently, as shown in FIG.
9
(C), a SAW element
6
is mounted at the bottom and electrically connected to the printed wirings
4
, e.g., by wire bonding, etc.
Next, as shown in FIG.
9
(D), the frequency adjustment of the SAW element
6
is performed. More specifically, a plasma, for example, and the like are irradiated from the opening
2
b
of the substrate
2
onto the SAW element
6
, and a piezoelectric substrate or electrodes formed on a piezoelectric substrate of the SAW element
6
are etched. This frequency adjustment is performed while the SAW element
6
is driven by the electronic component
5
. Then, the operation is performed until a desirable frequency characteristic of the SAW element
6
is obtained.
Subsequently, as shown in FIG.
9
(E), a cover
3
is arranged on the opening of the substrate
2
, and the substrate
2
and the cover
3
are joined with a sealant, thereby hermetically sealing the inside of the hollow component
2
a
to complete a SAW device
1
.
SUMMARY OF THE INVENTION
In the related art SAW device
1
of
FIG. 8
, the electronic component
5
and the SAW element
6
are arranged side by side. Namely, the electronic component
5
and the SAW element
6
are arranged in the same space, i.e., within the hollow component
2
a.
In this instance, if the SAW device
1
is actuated, the electronic component
5
emits heat. The heat emitted from the electronic component
5
is directly transmitted to the SAW element
6
via the atmosphere and the bottom in the hollow component
2
a
of the substrate
2
. The heat greatly affects the temperature characteristics of the SAW element
6
and causes a problem, i.e., that the SAW element
6
cannot display a desirable frequency characteristic.
On the other hand, a so-called two-stage superposed package structure has been proposed as a method for mounting an electronic component
5
and a SAW element
6
in different spaces. When frequency adjustment is performed in a state in which the SAW element
6
is driven by the electronic component
5
, however, the process of mounting the electronic component
5
and the SAW element
6
on the packages, respectively, and the process for adhesion and conduction of respective packages must be performed, thereby complicating the manufacturing process.
Accordingly, the present invention addresses the problem referred to above, and provides a SAW device and a manufacturing method thereof which enhances reliability and yield.
The invention in accordance with a first aspect of the invention provides a surface acoustic wave device having a surface acoustic wave element and an electronic component that drive controls the surface acoustic wave element, provided with a first substrate, which has a first connecting terminal having a first hollow component formed therewith, including an opening that accommodates the electronic component and electrically connected to the electronic component formed in the first hollow component, and a second connecting terminal formed in the vicinity of the opening and electrically connected to the first connecting terminal, and a second substrate, which is mounted so that one face side is joined to the opening of the first substrate, and the other face side allows the surface acoustic wave element to be electrically connected to the second connecting terminal, and a cap which is joined to the first substrate and has a second hollow component that hermetically seals the surface acoustic wave element.
In accordance with the structure of the first aspect of the invention, the first hollow component is formed in the first substrate, and the electronic component is mounted in this hollow component. On the other hand, the second substrate has a structure such that one face side is joined to the first substrate, and the surface acoustic wave element is mounted to the other face side. Then, the cap, that seals the surface acoustic wave device in the second hollow component is joined to the first substrate.
Thus, only the electronic component is mounted in the hollow component of the first substrate, and the surface acoustic wave element is mounted on the other face side of the second substrate. Namely, the surface acoustic wave element and the electronic component are arranged in separate spaces partitioned by the first substrate and the second substrate. Therefore, for example, when a plasma is irradiated on the surface acoustic wave element, the electronic component is not exposed to the plasma during the frequency adjustment of the surface acoustic wave device. Moreover, the influence of the heat and electromagnetic wave generated when the electronic component is actuated on the surface acoustic wave element can be suppressed to the minimum.
The invention in accordance with a second aspect of the invention provides a surface acoustic wave device in which the first substrate and the second substrate are joined with a sealant on the lateral face side of the second substrate in the structure of the first aspect of the invention.
In accordance with the structure of the second aspect of the invention, the first substrate and the second substrate are in a state in which they are joined with a sealant applied on the lateral face side of the second substrate, thereby surely hermetically sealing the first hollow component of the first substrate.
The invention in accordance with a third aspect of the invention provides a surface acoustic wave device in which the second substrate and the cap are joined to the first substrate with same sealant, respectively in the structure of either of the first or second aspects.
In accordance with the structure of the third aspect of the invention, with the joint of the first substrate and the second substrate and the joint of t
Dougherty Thomas M.
Oliff & Berridg,e PLC
Seiko Epson Corporation
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