Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-05-11
2002-01-08
Paladini, Albert W. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C257S707000, C257S719000, C257S718000
Reexamination Certificate
active
06337796
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-148459 filed on May 19, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device mount structure in which a semiconductor device is mounted to a heat dissipating member.
2. Description of Related Art
One previously proposed semiconductor device mount structure is schematically shown in
FIG. 5. A
semiconductor device
20
is constructed as a package in which a semiconductor chip
21
, such as a power MOSFET, that generates substantial heat upon operation thereof is encapsulated within a resin encapsulating material through a molding process. A heat dissipating member (fins)
10
is made of a highly heat conductive material, such as copper or aluminum. The semiconductor device
20
is secured to a mounting surface of the heat dissipating member
10
by a screw
100
. Leads
22
extend out from the semiconductor device
20
and are electrically connected to a printed circuit board (not shown).
An interface member
30
, such as a heat conductive grease material or a heat conductive sheet material, is placed between the semiconductor device
20
and the heat dissipating member
10
. Heat generated from the semiconductor chip
21
is conducted to the heat dissipating member
10
through the interface member
30
. Then, the heat conducted to the heat dissipating member
10
is dissipated from the heat dissipating member
10
, for instance, into the atmosphere.
Since the semiconductor device
20
is secured to the heat dissipating member
10
by the screw
100
, the heat dissipating property is greatly influenced by a type of material used for the heat dissipating member
10
, a flatness of the mounting surface of the heat dissipating member
10
, a screw torque of the screw
100
or the like. Thus, it is difficult to achieve a stable good heat dissipating property (low heat resistance).
That is, as shown in
FIG. 6
, the screw
100
is not located right above the heat source (mainly the semiconductor chip
21
) to bias the heat source against the heat dissipating member
10
. Thus, when the screw
100
is tightened, a bottom side of the semiconductor device
20
below the heat source can be lifted from the heat dissipating member
10
, so that the heat resistance between the semiconductor device
20
and the heat dissipating member
10
is increased.
Furthermore, in such a mount structure using the screw
100
for securing the semiconductor device
20
, the contact between the semiconductor device
20
and the heat dissipating member
10
is greatly influenced by the flatness of the mounting surface of the heat dissipating member
10
. In addition, if the heat dissipating member
10
is made of a soft material, such as copper, the tightening of the screw
100
may cause deformation of the mounting surface of the heat dissipating member
10
. Thus, the bottom side of the semiconductor device
20
below the heat source may be lifted or spaced from the heat dissipating member
10
.
Also, in the mount structure shown in
FIG. 5
, the circuit board (not shown) to which the leads
22
are connected is arranged above the semiconductor device
20
. Thus, the semiconductor device
20
mounted to the heat dissipating member
10
is positioned between the heat dissipating member
10
and the circuit board. As a result, the heat dissipated from the semiconductor device
20
may affect the performance of the circuit board.
SUMMARY OF THE INVENTION
The present invention addresses the above disadvantages. Accordingly, it is an objective of the present invention to provide a semiconductor device mount structure that achieves stable effective heat dissipating property and restrains influences of heat radiated from a semiconductor device on a circuit board arranged above the semiconductor device.
To achieve the objective of the present invention, there is provided a semiconductor device mount structure including a heat dissipating member, a circuit board, a semiconductor device and a leaf spring member. The heat dissipating member has a mounting surface. The circuit board is opposed to the mounting surface of the heat dissipating member. The semiconductor device is mounted to the mounting surface of the heat dissipating member. The semiconductor device is electrically connected to the circuit board. The leaf spring member is arranged between the semiconductor device and the circuit board in such a manner that the leaf spring member biases the semiconductor device against the mounting surface of the heat dissipating member. The leaf spring member has a heat insulating material integrated on one side thereof which faces the circuit board.
The semiconductor device may includes a heat generating element, such as a power MOSFET. The leaf spring member may resiliently contacting the semiconductor device on a portion of a surface of the semiconductor device, which is located along a line that extends perpendicular to the mounting surface of the heat dissipating member and that passes through the heat generating element.
REFERENCES:
patent: 4110549 (1978-08-01), Goetze et al.
patent: 4509839 (1985-04-01), Lavochkin
patent: 4710852 (1987-12-01), Keen
patent: 5812376 (1998-09-01), Mach et al.
patent: 5870287 (1999-02-01), Rodriguez et al.
patent: 5991151 (1999-11-01), Capriz
patent: 6049469 (2000-04-01), Hood, III
patent: 6122170 (2000-09-01), Hirose et al.
patent: 6185100 (2001-02-01), Bentz et al.
patent: 07-22593 (1995-04-01), None
patent: 09-232487 (1997-09-01), None
Konda Shinichi
Sato Taketoshi
Yamada Masao
Alcalá José H.
Denso Corporation
Law Office of David G. Posz
Paladini Albert W.
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