Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For plural devices
Reexamination Certificate
2002-05-28
2003-12-16
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For plural devices
C257S693000, C257S698000
Reexamination Certificate
active
06664629
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device containing a plurality of transistors, and more specifically to the structure of the electrode of the semiconductor device.
2. Description of the Related Art
In accordance with the present trend toward smaller electronic equipment, a semiconductor device configured by a smaller module containing a plurality of heat-producing semiconductor elements is demanded.
An existing semiconductor device (power module) is described below by referring to
FIGS. 1 and 2
. A power module
51
includes a plurality of semiconductor elements. To the bottom of the power module
51
, a heat conductive base plate
52
formed by a heat conductive ceramic plate is attached as a heat conductive member.
On the top surface of the heat conductive base plate
52
, a substrate
55
and a substrate
56
are provided. The substrate
55
is formed by a conductor layer
55
a
and an insulating layer
55
b
, and the insulating layer
55
b
is in contact with the heat conductive base plate
52
. On the other hand, the substrate
56
is formed by a conductor layer
56
a
and an insulating layer
56
b
, and the insulating layer
56
b
is in contact with the heat conductive base plate
52
. A plurality of semiconductor elements
57
are provided on the top surface of the conductor layer
55
a
, and a plurality of semiconductor elements
58
are provided on the top surface of conductor layer
56
a
. The semiconductor elements
57
and
58
are MOSFETs. A drain of the MOSFET is formed on one surface of each of the semiconductor elements
57
and
58
, and a source and a gate are formed on the other surface of the MOSFET. The drain of each semiconductor element
57
is in contact with the conductor layer
55
a
of the substrate
55
, and the drain of each semiconductor element
58
is in contact with the conductor layer
56
a
of the substrate
56
.
A substrate
53
is provided in the central area on the top surface of the heat conductive base plate
52
. The substrate
53
is formed by a conductor layer
53
a
and an insulating layer
53
b
, and the insulating layer
53
b
is in contact with the heat conductive base plate
52
. A source-drain electrode
54
is connected to the conductor layer
53
a.
The substrates
55
,
56
, and
53
(and semiconductor elements
57
and
58
) are encompassed by a resin case
59
. A drain electrode
60
, a source electrode
61
, and gate electrodes
62
and
63
are attached to the resin case
59
. The resin case
59
is fixed to the heat conductive base plate
52
.
As shown in
FIGS. 1 and 2
, wire bonding connects the drain electrode
60
with the conductor layer
55
a
of the substrate
55
, the source of each semiconductor element
57
with the conductor layer
53
a
of the substrate
53
, the conductor layer
53
a
with the conductor layer
56
a
of the substrate
56
, the source of the semiconductor element
58
with the source electrode
61
, the gate of the semiconductor element
57
with the gate electrode
62
, and the gate of each semiconductor element
58
with the gate electrode
63
.
In this semiconductor device, if the substrates
53
,
55
, and
56
are made small, then a smaller power module can be produced. However, it is necessary for the substrate
53
to reserve an area for wire bonding and an area for the source-drain electrode
54
. In addition, it is necessary to increase the number of the semiconductor elements
57
and
58
in order to increase the capacity of the power module
51
, thereby also requiring larger substrates
55
and
56
. As a result, there has been a lower limit for the size of the substrates
53
,
55
, and
56
. That is, it has not been easy to realize a smaller semiconductor device such as a power module, etc.
SUMMARY OF THE INVENTION
The present invention aims at downsizing a semiconductor power module including a plurality of semiconductor elements.
The semiconductor device according to the present invention includes a plurality of semiconductor elements, a case provided as encompassing the plurality of semiconductor elements, and an electrode which is incorporated into the case for the main current of the semiconductor elements. These components are arranged such that the electrode bridges over the area of the semiconductor elements when the case is fixed in a predetermined position for the semiconductor elements.
According to this structure, the semiconductor elements (or their circuits) can be provided under the electrode. Therefore, a smaller semiconductor device can be realized. In addition, since the electrode is incorporated into the case, the assembly task for the semiconductor device can be simpler.
This semiconductor device can be configured such that the terminals for electric connection between the semiconductor device and the circuits outside the semiconductor device can also be incorporated into the electrode. With the configuration, since it is not necessary to connect the electrode to the terminals, the assembly task for the semiconductor device can be yet simpler.
This semiconductor device can also be configured such that the electrode can be connected to the semiconductor elements through wire bonding. With the configuration, the space in the case can be efficiently utilized.
This semiconductor device can be configured such that the electrode can directly or indirectly contact the metal contact surface provided in a predetermined position for the semiconductor elements so that the metal contact surface is connected to the semiconductor elements through the wire bonding. With the configuration, the wire can be applied before fixing the case, thereby realizing an easier bonding operation.
Furthermore, this semiconductor device can also be configured such that partitioning members for sectioning the area inside the case can be provided at the bottom portion of the electrode. With the configuration, a gel, if it is filled inside the case, can be protected against shaking. As a result, an excess tension on the wire can be avoided.
REFERENCES:
patent: 5530282 (1996-06-01), Tsuji
patent: 5714787 (1998-02-01), Eguchi et al.
patent: 6388316 (2002-05-01), Matsumoto
patent: 2002/0158327 (2002-10-01), Maeno et al.
patent: 6-283639 (1994-10-01), None
Huynh Andy
Kabushiki Kaisha Toyota Jidoshokki
Morgan & Finnegan , LLP
Nelms David
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