Semiconductor device having heat radiating member

Details Semiconductor device having heat radiating member Semiconductor device having heat radiating member

2001-05-02

2002-08-13

Chervinsky, Boris (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S705000, C361S707000, C361S708000, C361S719000, C361S720000, C257S717000, C257S718000, C257S719000, C174S016300, C165S080200, C165S080300, C165S185000

Reexamination Certificate

active

06434006

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon Japanese Patent Application Nos. 2000-140554 filed on May 12, 2000, and 2001-72444 filed on Mar. 14, 2001, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor device having a ceramic substrate on which a semiconductor element is disposed, and a heat radiating member which is fixed to the ceramic substrate so that the heat radiating member radiates heat transferred through the ceramic substrate.
2. Description of the Related Art
Recently, semiconductor devices have been required to satisfy high performance, for example, large scale integration and application of high power thereto. Accordingly, power consumption in the semiconductor devices may increase with the large scale integration and the high power application.
On the other hand, while a base plate on which a semiconductor element is disposed and a case in which the semiconductor element is contained are required to be miniaturized.
Therefore, it is difficult to radiate heat from the semiconductor device sufficiently because of the increase of the power consumption and a decrease of a radiating heat area in the device based on the miniaturization.
A prototype as shown in
FIGS. 7A
to
7
C was studied to solve the above-mentioned problem.
FIG. 7A
shows a cross sectional view of a ECU (Electric Controlling Unit) for a vehicle as the semiconductor device.
FIG. 7B
is a cross sectional view taken along line VIIB—VIIB in FIG.
7
A.
A ceramic substrate
21
constituting a hybrid IC (Integrated Circuit) that includes an LSI and a high power IC is disposed on a printed circuit board
25
through lead terminals
29
which electrically connect the hybrid IC and the printed circuit board
25
. Moreover, the ceramic substrate
21
is fixed to a fin (heat radiating member)
23
directly. The ceramic substrate
21
, the printed circuit board
25
, and the fin
23
are collectively disposed in a case
24
.
In this structure, heat radiation can be improved by fixing the ceramic substrate having the hybrid IC directly to the heat radiating fin
23
.
Incidentally, the printed circuit board
25
is fixed to the case
24
by using screws
26
. Similarly, the fin
23
is fixed to the case
24
and the printed circuit board
25
by using screws
27
,
28
. Accordingly, the heat radiating fin
23
contacts an inner wall of the case
24
when the fin
23
is fixed to the case
24
as shown in
FIGS. 7A and 7B
. Therefore, heat generated in the ceramic substrate
21
by semiconductor elements in the power IC is externally radiated from the case
4
through the fin
23
. In addition, even when the case
24
holds several ceramic substrates, a whole dimension of the case
24
can be miniaturized by fixing the several ceramic substrates to the fin
23
in common.
Usually, a surface of the printed circuit board and each electrically connecting portion are covered and protected by a moisture-proof material such as a humid-sealing. The portion which needs a moisture-proof described above is covered by the moisture-proof material that is coated by spray and the like after the ceramic substrate
21
and the fin
23
are mounted on the printed circuit board
25
. Then, the printed circuit board
25
is put in the case
24
. Therefore, the moisture-poof material adheres to the fin
23
or the case
24
occasionally.
FIG. 7C
is a enlarged view showing a portion around a contacting interface between the case
24
and the fin
23
.
Usually, moisture-proof material has a heat insulating characteristic. Therefore, in the case that a moisture-proof material K
0
adheres to the interface between the case
24
and the fin
23
, heat radiation of the device becomes worse because heat resistance between the case
24
and the fin
23
increases by the moisture-proof material K
0
.
To avoid adhering of the moisture-proof material to the interface between the case
24
and the fin
23
, a rigorous process control or special structure is required. Thus, it may take much time to assemble the printed circuit board
25
and the case
24
, or structure of the fin
23
or the case
24
becomes complicated.
In addition, the heat radiation of the device also become worse in the case that a contact surface of the case
24
or the fin
23
is deformed by an error in process, that is, in the case that the contact surface is not flat. This is because a contact area between the case
24
and the fin
23
is reduced. Thus, accuracy in processing of the case
24
and the fin
23
is required to make the contact surface flat.
SUMMARY OF THE INVENTION
This invention has been conceived in view of the background as described above and an object of the invention is to provide a semiconductor device in which heat radiating path is secured.
According to the invention, protrusions are formed on at least one of surfaces of a body member of a semiconductor device such as a case and a heat radiating member fixed to the body member. The heat radiating member contacts the body member through the protrusions. The protrusions serve as a heat radiating path.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings.


REFERENCES:
patent: 4151547 (1979-04-01), Rhoades et al.
patent: 4384610 (1983-05-01), Cook et al.
patent: 4654754 (1987-03-01), Daszkowski
patent: 4689720 (1987-08-01), Daszkowski
patent: 4961106 (1990-10-01), Butt et al.
patent: 5052481 (1991-10-01), Horvath et al.
patent: 5075822 (1991-12-01), Baumler et al.
patent: 5309979 (1994-05-01), Brauer
patent: 5461541 (1995-10-01), Wentland, Jr et al.
patent: 6131646 (2000-10-01), Kelley
patent: 6185101 (2001-02-01), Itabashi et al.
patent: 6225559 (2001-05-01), Hubner et al.
patent: A-4-243154 (1992-08-01), None
patent: A-11-186687 (1999-07-01), None
U.S. application Ser. No. 09/615,756, Itabashi et al., filed Jul. 13, 2000.

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