Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-01-22
2001-03-20
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S705000, C361S707000, C174S252000, C165S080300, C310S06800R
Reexamination Certificate
active
06205024
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a heat sink for a rectifier of an alternator, and more particularly to a heat sink for a rectifier with diodes embedded in the heat sink completely.
BACKGROUND OF THE INVENTION
Conventional rectifiers for alternators known in the art have diodes that are secured to the surface of a heat sink by soldering or brazing. When an alternating current goes through the diodes, heat generated by the diodes may not be well distributed through the heat sink because the diodes are only attached to the heat sink with small contact areas. Therefore, heat may be dissipated insufficiently and result in damage of the rectifier.
In the conventional rectifier, the anode or cathode of a diode is typically secured to the heat sink by soldering or brazing. The attachment between the heat sink and a diode is only accomplished by one small attaching end. After a long period of vibration or a huge unexpected shake, the attachment may be loose or even totally disconnected. In addition, the diode is usually attached on an external surface that is susceptible to water infiltration.
A known technique using press-fit diodes has been adopted to overcome the drawbacks just mentioned above. As in
FIG. 8
, the metal case
53
is used to package the die
52
with the nail connector
51
. The combinations are called press-fit diodes
5
. Die
52
is completely embedded in the metal case
53
to avoid water infiltration and particle contamination. The press-fit diodes
5
are installed into the holes
21
and holes
31
from the bottom of the first sink plate
2
and the second sink plate
3
. Because the press-fit diodes
5
are completely pressed into the holes
21
and
31
, heat generated due to rectification can be well distributed around the first sink plate
2
and the second sink plate
3
. And, the die
52
is completely secured. Therefore, the drawbacks described above can be overcome. However, there are still some shortcomings. The metal case
53
should be made by casting or lathing process. This makes the cost higher than before. The press-fit diodes
5
must be formed firstly before they are pressed into holes
21
and
31
. This increases the labor cost. In addition, when press-fit diodes
5
are installed into holes
21
and
31
, gaps exist between the metal case
53
and the sink plates
2
or
3
. This will significantly reduce the heat dissipation efficiency.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide an improved heat sink to uniformly distribute heat generated by the diodes. In the heat sink, holes are created for dice of diodes. Diodes may be formed and completely embedded into the main body of the heat sink. Therefore, the dice packaging of diodes may be accomplished during rectifier manufacturing process. Because diodes are built into holes in the heat sink, the heat on diodes may be well distributed around the heat sink. Therefore, heat dissipation by the heat sink will be more efficient with the improved structure.
According to the present invention, dice of diodes are completely embedded in the holes formed on the heat sinks. Dice of diodes may be completely placed into a hole and then an insulating material is installed to fill up the space between dice and the heat sink. Therefore, during heat sink manufacturing, diode packaging process is also accomplished at the same time.
By combining the manufacturing of the heat sink and the packaging of the diodes, the attachment between diodes and the heat sink is greatly enhanced. Because dice of diodes are completely built in the holes and sealed up, diodes are well protected to prevent from water infiltration and particle contamination.
Another object of the invention is to provide an improved heat sink with simplified assembling steps and reduced manufacturing cost. By packaging dice of diodes directly into holes in the heat sink, several assembled parts are eliminated during the manufacturing process. Not only is the assembly process simplified but also the manufacturing cost is reduced.
Other features and advantages of the invention will become better understood from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 3927338 (1975-12-01), Vieilleribiere
patent: 3959676 (1976-05-01), Striker
patent: 4059778 (1977-11-01), Sohnle
patent: 5043614 (1991-08-01), Yockey
patent: 5424594 (1995-06-01), Saito et al.
patent: 5473208 (1995-12-01), Stihi
patent: 5646838 (1997-07-01), Keidar et al.
patent: 5659212 (1997-08-01), DePetris
patent: 5737210 (1998-04-01), Barahia
patent: 5812388 (1998-09-01), Keidar et al.
patent: 5828564 (1998-10-01), Mori et al.
patent: 5866963 (1999-02-01), Weiner et al.
Chen Yi-Ching
Shih Chun-Min
Chervinsky Boris L.
Kalem Technology Corporation
Picard Leo P.
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