Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-09-07
2001-10-16
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S702000, C361S705000, C361S719000, C361S806000, C257S723000, C257S718000, C257S692000, C174S016300, C307S010100
Reexamination Certificate
active
06304448
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure of a power module, and more particularly to a structure of a power module comprising an insulating substrate having a power semiconductor device mounted thereon and a control substrate on which a control IC for controlling the power semiconductor device is mounted.
2. Description of the Background Art
FIGS. 5 and 6
are perspective and sectional views showing a structure of a conventional power module. As shown in
FIG. 6
, the conventional power module comprises an insulating substrate
105
and a control substrate
113
on which circuit patterns (not shown) are formed respectively, interconnection leads
110
and
120
, and an insulating case
107
. A power semiconductor device
109
is mounted on the insulating substrate
105
through a solder
108
. The insulating substrate
105
is provided in contact with a metallic base plate
102
through a solder
104
.
A control IC
115
for controlling the power semiconductor device
109
is mounted on the control substrate
113
through a solder
114
. One of ends of the interconnection lead
110
is electrically connected to the insulating substrate
105
or the power semiconductor device
109
through a metal wire
111
. The other end of the interconnection lead
110
is electrically connected to an electrode
122
provided on the control substrate
113
. The electrode
122
is electrically connected to the control IC
115
. One of ends of the interconnection lead
120
is electrically connected to the power semiconductor device
109
through a metal wire
121
. The other end of the interconnection lead
120
is electrically connected to an electrode
123
provided on the insulating case
107
.
The insulating substrate
105
, the control substrate
113
and the interconnection leads
110
and
120
are provided in the insulating case
107
. An internal space of the insulating case
107
provided below the control substrate
113
is filled with a silicone gel
112
. Moreover, a cover
117
is fixed to a top of the insulating case
107
. The control IC
115
is electrically connected to a control connector
119
provided on the cover
117
through an external connecting terminal
118
soldered onto the control substrate
113
.
The base plate
102
is fixed to a heat sink
101
with a bolt
103
. A thermal conduction grease
116
is coated comparatively thickly (approximately several hundreds &mgr;ms) between the base plate
102
and the heat sink
101
.
According to such a conventional power module, however, an electromagnetic shield is not fully formed for the insulating substrate
105
and the control substrate
113
. Therefore, there has been a problem in that the power module is easily influenced by external noises made by a driving motor or the like and reliability is deteriorated.
Moreover, the base plate
102
and the heat sink
101
are fixed to each other with the bolt
103
. For this reason, it is necessary to provide a space for forming a bolt hole for the bolt
103
in an upper surface of the heat sink
101
. Consequently, there has been a problem in that the size of the heat sink
101
is increased.
Furthermore, a warp is easily generated on the insulating case
107
and the base plate
102
by heating for thermosetting the silicone gel
112
and heating for bonding the insulating substrate
105
to the base plate
102
. Consequently, the thickness of the thermal conduction grease
116
cannot be reduced so that a thermal resistance is increased and heat-radiation effects produced by the heat sink
101
are reduced.
SUMMARY OF THE INVENTION
In order to solve the problems, it is an object of the present invention to obtain a power module which is mainly excellent in electromagnetic shielding effects, is rarely influenced by external noises and acts as an external noise source with difficulty.
A first aspect of the present invention is directed to a power module comprising an insulating substrate having a main surface on which a power semiconductor device is mounted, a control substrate on which a control IC for controlling the power semiconductor device is mounted, a conductive support plate to which the insulating substrate and the control substrate are fixed, and a conductive case fixed to a peripheral portion of the support plate for surrounding the insulating substrate and the control substrate together with the support plate.
A second aspect of the present invention is directed to the power module according to the first aspect of the present invention, further comprising a heat sink provided in the case and kept in contact with a back face of the insulating substrate which is opposite to the main surface, the support plate including a refrigerant inlet-outlet coupled to the heat sink, an electrode electrically connected to the power semiconductor device, and a control connector electrically connected to the control IC, all of them being provided through the support plate.
A third aspect of the present invention is directed to the power module according to the second aspect of the present invention, wherein the power semiconductor device is a voltage-source inverter, the power module further comprising a DC capacitor provided in contact with the heat sink opposite to the insulating substrate in the case.
A fourth aspect of the present invention is directed to the power module according to any of the first to third aspects of the present invention, further comprising a shield plate provided between the insulating substrate and the control substrate in the case.
A fifth aspect of the present invention is directed to the power module according to any of the first to fourth aspects of the present invention, wherein the case and the support plate are bonded to each other with sealing property kept therein.
A sixth aspect of the present invention is directed to the power module according to the fifth aspect of the present invention, wherein an internal space constituted by the case and the support plate is filled with an inactive material having insulating property.
A seventh aspect of the present invention is directed to the power module according to the sixth aspect of the present invention, wherein the material functions as a refrigerant, the power module further comprising a fan provided in the case for circulating the material in the case.
According to the first aspect of the present invention, both the insulating substrate and the control substrate are surrounded by the conductive case and the support plate. Therefore, it is possible to obtain a power module which is excellent in electromagnetic shielding effects, is rarely influenced by external noises and acts as an external noise source with difficulty.
According to the second aspect of the present invention, the refrigerant inlet outlet, the electrode and the control connector are collectively formed on the support plate. Consequently, the structure of the case can be simplified.
According to the third aspect of the present invention, it is possible to relieve the influence of external noises on the DC capacitor. In addition, the DC capacitor is provided in contact with the heat sink. Therefore, heat generated from the DC capacitor can be absorbed properly through the heat sink.
According to the fourth aspect of the present invention, it is possible to obtain electromagnetic shielding effects between the power semiconductor device and the control substrate.
According to the fifth aspect of the present invention, it is possible to obtain a power module which is excellent in dustproof property and waterproof property.
According to the sixth aspect of the present invention, the reliability of the power module can be enhanced.
According to the seventh aspect of the present invention, it is possible to wholly cool the inside of the case with the circulated refrigerant, resulting in an enhancement in heat-radiation effects.
REFERENCES:
patent: 5291065 (1994-03-01), Arai et al.
patent: 5504378 (1996-04-01), Lindberg et al.
patent: 5751058 (1998-05-01), Matsuki
patent:
Fukada Masakazu
Nakajima Dai
Takanashi Ken
Datskovsky Michael
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tolin Gerald
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