Electricity: motive power systems – Synchronous motor systems – Armature winding circuits
Reexamination Certificate
2000-01-28
2001-11-06
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Synchronous motor systems
Armature winding circuits
C318S801000, C361S728000, C361S736000, C361S772000, C257S692000
Reexamination Certificate
active
06313598
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a structure of a power semiconductor module incorporating peripheral circuits.
BACKGROUND OF THE INVENTION
As one of the means for decreasing the cost of a power semiconductor module, it is possible to fabricate the package by transfer molding as in the fabrication of an IC package. Power semiconductor modules having cross-sectional structures as shown in FIG.
3
and
FIG. 20
are typical examples.
FIG. 3
shows an IGBT module incorporating a driver (three-phase inverter module) produced by mounting six elements, each including an IGBT and flywheel diode (FWD), and four chips having a gate drive IC (incorporating various protecting circuits) for the IGBT, on a lead frame
11
and subjecting the same to transfer molding. The bare chip power elements (IGBT, FWD)
14
and the bare chip gate drive ICs
30
are mounted on a common lead frame
11
serving as both a power system terminal
12
and a control terminal
13
, and electrical interconnections are made with Al (aluminum) wires
15
, and then the same is subjected to transfer molding (first molding) with a thermosetting resin
31
. Then, the same and a heat radiating plate
10
together are subjected to transfer molding with a thermosetting resin
32
(second molding). Further, insulating work between the lead frame
11
and the heat radiating plate
10
is performed with the thermosetting resin
32
at the same time as the second molding. Hence, a resin containing a large quantity of alumina filler is used as the thermosetting resin
32
for reducing the heat resistance.
According to the IGBT module as described above, the only parts used other than the Si chip are the lead frame
11
, the heat radiating plate
10
, and the sealing resin. Hence, it has an advantage of being fabricated at low cost.
FIG. 20
shows an example of a hybrid IC mounting power elements thereon. Namely, it shows a technique for attaining a performance higher than the IGBT module incorporating a driver shown in FIG.
3
. There are mounted bare chip power elements
14
and a thick film circuit board (alumina)
202
on a lead frame
200
. A flip-chipped IC
201
is mounted on the thick film circuit board
202
, whereby a thick film resistor and the like and a high performance circuit are formed. The power element
14
and the thick film circuit board
202
are connected to the lead frame
200
with an Al wire
15
and subjected to transfer molding with a thermosetting resin
16
. Since, as opposed to the case of
FIG. 3
, this example uses the thick film circuit board
202
in addition to the lead frame
200
, it has a characteristic feature of attaining a higher performance.
The above described transfer mold type power modules have the following problems in terms of compatibility between achievement of high performance of the module and reduction in the fabrication cost and, further, in terms of reliability of the module.
In the case of the IGBT module shown in
FIG. 3
, the electrical wiring pattern is provided by only the lead frame
11
. Hence, the number of components can be decreased and the fabrication process can be greatly simplified. It, therefore, has a structure well designed in terms of fabrication cost. However, in order to lower the resistance of the power system terminal
12
, it is impossible to decrease the thickness of the lead frame
11
and, therefore, a fine pattern of the lead frame
11
cannot be produced. Accordingly, the control circuit that can be mounted is limited to a circuit not requiring a fine pattern. Namely, it is limited to such a circuit as an IGBT module incorporating a driver mounting only a gate drive IC thereon as in the case of FIG.
3
. Further, since it is not necessary to consider heat radiation therefrom, the gate drive IC
30
, in itself, is a part not required to be mounted on the lead frame
11
. Hence, this means that the area of the module increases by a region occupied by the gate drive IC
30
. This is unfavorable from the point of view of fabrication cost when transfer molding, to which miniaturization is the key, is executed.
On the other hand, in the case of the structure shown in
FIG. 20
, a fine pattern can be easily produced for the control circuit because the thick film circuit board
202
serving as the control circuit is mounted on the lead frame constituting the power system terminal. Hence, a high performance IC such as an MPU can be incorporated therein. However, the area of the lead frame
200
becomes large and there arises the same problem as the case described above in view of the fabrication cost.
Further, as a problem common with FIG.
3
and
FIG. 20
, it can be mentioned that they are both vulnerable to noises. Since both the control circuit and the power element are mounted on the same lead frame, capacity coupling is caused between the power element
14
and the control circuit (the gate drive IC
30
or the thick-film circuit board
202
) through the lead frame or the radiating plate and the circuit is easily affected by noise due to potential changes in the power element
14
.
SUMMARY OF THE INVENTION
The invention was made in view of the above described problems and it provides a power semiconductor module which, while attaining higher performance, has a low-cost or high reliability characteristic.
The power semiconductor module according to the invention comprises a power semiconductor element included in a power circuit portion and mounted on a metal base through an insulator and a first resin molded to the power semiconductor element such that the surface of the metal base is exposed. On the first resin, there is disposed a control circuit element included at least in a portion of the control circuit. Further, the power semiconductor module has a control terminal connected to the power circuit portion and an exposed portion in the surface of the first resin. At least a portion of the control circuit is connected with the power circuit portion at the exposed portion of the control terminal.
According to the present invention, since the control circuit element is disposed on the first resin molded to the power semiconductor element, it is possible to attain a higher performance control circuit not affected by the structure of the power circuit portion. Further, since the power semiconductor module according to the present invention is of a resin-mold type, it can be fabricated at low cost. Further, since the control circuit portion is disposed on the first resin that is molded to the power semiconductor element mounted on a metal base, the control circuit is hardly affected by noise from the power circuit portion. Therefore, the reliability can be improved.
A power converting apparatus such as an inverter and a converter can be structured by the use of the power semiconductor module according to the above-described invention. Motor driving systems for driving motors constructed of such a power converter apparatus have a characteristic feature of being fabricated at low cost or having a high reliability.
REFERENCES:
patent: 5124888 (1992-06-01), Suzuki et al.
patent: 5457604 (1995-10-01), Ando
patent: 5497289 (1996-03-01), Sugishima et al.
patent: 5777851 (1998-07-01), Yamamoto
patent: 6091604 (2000-07-01), Plougsgaard et al.
patent: 3-272163-A (1991-12-01), None
patent: 10-135405-A (1998-05-01), None
Ogawa Toshio
Tamba Akihiro
Yamada Kazuji
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Ro Bentsu
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