Wave transmission lines and networks – Long line elements and components – Strip type
Reexamination Certificate
2002-05-24
2003-12-02
Tokar, Michael (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Strip type
C333S033000, C333S204000, C333S247000, C333S238000, C333S160000, C361S761000, C361S764000, C361S780000
Reexamination Certificate
active
06657523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stacked radio-frequency module, and in particular, to improvements in the structure of a stacked radio-frequency module mounted in communications equipment such as radar or the like.
2. Description of the Related Art
FIGS. 13 and 14
are respectively a top view and a side cross sectional view of a conventional radio-frequency module. In
FIG. 13
, hatchings are drawn in certain sections in order to facilitate identification of each element. In
FIG. 14
, on the other hand, hatchings are not drawn in the cross sections for easier view.
FIGS. 13 and 14
show a dielectric substrate
20
, input/output pads
2
for radio-frequency signals (hereinafter referred to as “RF pads”), input/output pads
4
for power supply/control signals (hereinafter referred to as “DC/CONT pads”), via holes
7
within the dielectric substrate
20
, strip wiring paths
8
for radio-frequency signals (hereinafter referred to as “strip wiring paths”), active microwave circuits
9
(hereinafter referred to as “MMIC”s (Monolithic Microwave Integrated Circuit)), wiring paths
10
for control signals, and a metal sealing lid
12
. The multi-layer substrate
20
has a structure scraped inside such that the MMICs
9
can be stored inside, and forms a cavity structure along with the metal sealing lid
12
.
FIGS. 13 and 14
further show ground potential surfaces
11
of the module, bonding wires
13
(hereinafter referred to as “wires”), wire bonding surfaces
16
for radio-frequency signals and for power supply/control signals, and a mounting surface
17
for the metal sealing lid
12
.
Next, the operation of such a conventional radio-frequency module will be explained. A radio-frequency signal input from the strip wiring path
8
a
is connected via a bonding wire
13
a
to an RF pad
2
a
and is transmitted to an MMIC
9
a
. The radio-frequency signal is then subjected to signal modulation by the MMIC
9
a
, such as, for example, amplification, attenuation, and phase shift of the signal, and transmitted to an MMIC
9
b
through an RF pad
2
b
, a wire
13
b
, and an RF pad
2
c
. The radio-frequency signal is then subjected to a signal modulation in the MMIC
9
b
similar to that in the MMIC
9
a
. The radio-frequency signal is further supplied to an MMIC
9
c
through an RF pad
2
d
, a wire
13
c
, a strip wiring path
8
b
, a wire
13
d
, and an RF pad
2
e
, and is modulated at the MMIC
9
c
. After this process, the radio-frequency signal is transmitted through an RF pad
2
f
, a wire
13
e
, and an RF pad
2
g
to an MMIC
9
d
, and is modulated at the MMIC
9
d
. Finally, the radio-frequency signal is output outside the module through an RF pad
2
h
, a wire
13
f
, and a strip wiring path
8
c.
Power supply/control signals input from a plurality of DC/CONT pads
4
a
, on the other hand, are transmitted through respective wiring paths
10
a
,
10
b
,
10
c
, and
10
d
for control signals which passes through the dielectric substrate
20
, and wires
13
g
,
13
h
,
13
i
and
13
j
, to DC/CONT pads
4
b
,
4
c
,
4
d
, and
4
e
, to operate the MMICs
9
a
,
9
b
,
9
c
, and
9
d
. The ground potential surfaces
11
are grounded by a plurality of via holes
7
, to set the ground potentials for the MMICs
9
a
9
d.
Here, the MMICs
9
a
and
9
b
and MMICs
9
c
and
9
d
are respectively stored within two cavities formed by the dielectric substrate
20
and electromagnetically shielded by the metal sealing lid
12
. To prevent erroneous operations due to signal interference, the MMICs
9
a
and
9
b
and the MMICs
9
c
and
9
d
are separated spatially and according to radio frequencies.
However, with such conventional radio-frequency module, there is a problem in that increase in the module size cannot be avoided because of the number and size of the MMICs
9
necessary for the function of the module. In recent years, there is a tendency for the module size to increase because of the higher demands for more functions in a module. On the other hand, there is a conflicting desire that the size of the radio-frequency module be reduced in order to respond to the increasing demand for reduction of module size to allow the use of signals having higher frequency, and increasing demands for reduction of the size of wireless devices.
A conventional stacked module which has been proposed in order to reduce the above described problems associated with the increased number of functions and size reduction will now be explained. FIG.
15
is a cross sectional view of this improved stacked module and
FIG. 16
is a cross sectional enlarged view of a stacked bump section. In both
FIGS. 15 and 16
, the hatchings indicating the cross section are omitted for the sake of clarity.
FIGS. 15 and 16
show stacked bumps
23
, strip wiring paths
8
, active semiconductor chips
9
, dielectric substrates
20
, an exposed section
21
of the strip wiring path, and a package
22
. In this conventional example, a stacked module having a three-stage structure, in which three dielectric substrates
20
a
,
20
b
, and
20
c
are stacked, is shown. The dielectric substrates
20
a
,
20
b
, and
20
c
are collectively and air-tightly sealed by the package
22
.
Next, the operations in this conventional example will be described. A strip wiring path
8
a
provided on the dielectric substrate
20
a
is connected, via stacked bumps
23
, to a strip wiring path
8
b
provided on the dielectric substrate
20
b
at one stage above the dielectric substrate
20
a
. A strip wiring path exposure section
21
is formed on the strip wiring path
8
b
in which the dielectric substrate
20
b
is removed from the portion corresponding to the portion of the strip wiring path
8
b
to which the bumps
23
are to be connected. With such a structure, it is possible to connect the signal lines for the dielectric substrates
20
a
and
20
b
. Three dielectric multiple-layer substrates are stacked in the conventional stacked module, so that the stacked module has advantages that the mounting area for the module is extensively reduced, and, consequently, that the module size can be reduced.
However, because such a stacked module are developed for packages for storing active elements having relatively low operation frequency, such as a memory, the following problems are present when such a stacked module is employed as a radio-frequency module.
First, although the signal lines of the dielectric substrates are connected by stacked bumps, connection for ground signals, which is the counterpart to the signal lines, are not present between the stages, and, therefore, it cannot be assured that the radio-frequency signals will be reliably transmitted.
Second, because the clearance between the MMIC and the dielectric substrate at one stage above are determined only by the height of the stacked bumps, it has been difficult to secure sufficient clearance for mounting radio-frequency circuits. Because of this, the operation of the MMIC is influenced by the dielectric substrate at one stage above, and therefore, there is a problem in that desired characteristics may sometimes not obtained.
Also, because the shielding of the radio-frequency signals propagating through each stage is not sufficiently considered, the isolations between the stages are not sufficient. Because of this, there is a problem in that the signals to be transmitted may sometime interfere with each other, and smooth, reliable operation cannot be obtained.
Moreover, in order to connect the strip wiring path at the upper stage and the bumps, there is a need to expose the wiring path by precisely removing a portion in the dielectric substrate. Consequently, there is a problem in that a high-level manufacturing process is required and the cost is increased.
SUMMARY OF THE INVENTION
The present invention was conceived to solve the problems in the related art and one object of the present invention is to provide an improved stacked radio-frequency module having high functionality, a reduced size, and wider bandwid
Mitani Jun
Tarui Yukinobu
Yamaguchi Kazuhiro
Burns Doane , Swecker, Mathis LLP
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Linh Van
Tokar Michael
LandOfFree
Stacked radio-frequency module does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stacked radio-frequency module, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stacked radio-frequency module will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3106091