Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-04-04
2002-11-26
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S185000, C257S719000, C361S710000
Reexamination Certificate
active
06487079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a mounting structure for a heat sink onto an integrated circuit package mounted on a printed circuit board.
2 . Description of the Related Art
In recent years, portable electronic apparatus such as, for example, lap-top personal computers, appear widely on the market as electronic apparatus for which miniaturization and high reliability are required. In order to achieve a high performance of electronic apparatus of the type mentioned, it is necessary to use one or more integrated circuit packages having a great amount of heat generation. Therefore, in order to assure a heat radiation property of an integrated circuit package having a great amount of heat generation, a heat sink is used when an integrated circuit package is to be mounted onto a printed circuit board. A heat sink is required to be mounted such that it closely contacts, with certainty to a heat radiation face of an integrated circuit package in order to prevent an increase of the heat resistance by contact, to optimize the mounting structure for a heat sink onto an integrated circuit package.
FIG. 17A
is a top plan view of a conventional mounting structure for a heat sink onto an integrated circuit package, and
FIG. 17B
is a side elevational view of the same. In the present conventional example, an integrated circuit package
101
is mounted in a little floating condition on a printed circuit board
103
by soldering pins
102
of the integrated circuit package
101
to a conductor pattern (not shown) of the printed circuit board
103
, while depressions
106
are provided at upper face edge portions of a heat sink
105
having heat radiation fins
104
, and the heat sink
105
and the integrated circuit package
101
are held at the depressions
106
of the sink
105
and lower face edge portions of the integrated circuit package
101
by clips
107
having a substantially C-shaped section and made of a resin or the like (refer to, for example, U.S. Pat. No. 5,099,550).
FIG. 18A
is a top plan view of another conventional mounting structure for a heat sink onto an integrated circuit package, and
FIG. 18B
is a side elevational view of the same. In the present conventional example, pins
112
of an integrated circuit package
111
are mounted on a printed circuit board
114
by way of a frame
113
made of an insulator such as a resin. The frame
113
, having a substantially rectangular shape as viewed in plan, has a pair of projections
115
which project sidewardly at locations in the proximity of a diagonal line of an upper face thereof. A heat sink
117
having heat radiation fins
116
at an upper portion thereof is placed on an upper face of the integrated circuit chip
111
, and a clip
118
formed from a metal wire shaped in a crank shape is disposed on the heat sink:
117
while the opposite ends of the clip
118
are engaged with the projections
115
of the frame
113
so that the heat sink
117
is fixed relative to the integrated circuit package
111
(refer to Japanese Patent Laid-Open Application No. Showa 63-133557 or U.S. Pat. No. 4,745,456).
In the conventional example described with reference to
FIGS. 17A and 17B
, since the upper face edge portions of the heat radiation fin
105
are held by means of the clips
107
having a C-shaped section, it is necessary to provide the depressions
105
of a comparatively large size at the edge portions, and there is a problem in that the heat radiation area of the heat sink
105
is decreased and the cooling efficiency is deteriorated.
Meanwhile, in the conventional example described with reference to FIGS.
18
A and L
8
B, since it is necessary to interpose, already at the stage when the integrated circuit package
111
is to be mounted onto the printed circuit board
114
, the frame
113
between the integrated circuit package
111
and the printed circuit board
114
, there is a problem in that the manufacturing operability is low. Further, when the frame
113
made of a resin or the like is broken, for example, at a portion of a projection
115
, it is difficult to exchange the frame
113
, and the heat sink
117
can no longer be mounted.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a mounting structure for a heat sink which is high in cooling efficiency and is easy to mount.
It is another object of the present invention to provide a heat sink having a high cool efficiency.
According to the present invention, there is provided a mounting structure for a heat sink for mounting a heat sink onto an integrated circuit package mounted on a printed circuit board, which is constructed such that a guide member having a frame portion corresponding to an outer periphery of the integrated circuit package and support post portions protruding from the frame portion is fixed to the printed circuit board, that the heat sink is seated on an inner periphery of the guide member such that a lower face of the heat sink is closely contacted with an upper face of the integrated circuit package, and that a cover is fixed to the guide member at the support post portions such that it covers over outer peripheral edge portions of an upper face of the heat sink.
According to a preferred embodiment of the present invention, when the outer periphery of the integrated circuit packet is substantially equal to the inner periphery of the frame portion of the guide member, for example, the support post portions of the guide member have a profile wherein they protrude in upward and downward directions of the guide member and lower faces of the support post portions are fixed directly to the printed circuit board.
According to another preferred embodiment of the present invention, when the outer periphery of the integrated circuit package is substantially equal to the outer periphery of the frame portion of the guide member, for example, the support post portions of the guide member have a shape wherein they protrude only in the upward direction of the guide member and the guide member is adhered at a bottom face thereof to the integrated circuit package so that the guide member is fixed to the printed circuit board.
According to another aspect of the present invention, there is provided a mounting structure for a heat sink, which comprises a printed circuit board, an integrated circuit package mounted on the printed circuit board, a heat sink placed on the integrated circuit package, and a belt member provided around the integrated circuit package and the heat sink through a gap between the printed circuit board and the integrated circuit package for pressing the heat sink against the integrated circuit package.
According to a further aspect of the present invention, there is provided a heat sink, which comprises a base member having a lower face closely contacted with an upper face of an integrated circuit package and an upper face from which a plurality of heat radiation fins extend, a cover secured to the base member for closing an upper portion of the base member, and air blasting means provided on the cover for performing circulation of air by way of the fins, those of the plurality of fins at a portion corresponding to the air blasting means being shorter than the fins at the other portion.
In the present invention, since the heat sink is mounted on the integrated circuit package using the guide member and the cover of the particular constructions, a high cooling efficiency can be obtained and mounting of the heat sink is facilitated.
When the present invention is put into practice, the cooling efficiency can be further enhanced by constructing the heat sink so that it has a base member having heat radiation fins and air blasting means for Forcibly cooling the base member by air cooling.
Further, by putting the present invention into practice using a cover made of a resilient plate member having a shape curved toward the heat sink side, the heat sink can always be closely contacted with the integrated circuit package irrespective of a dispersion and
Fujitsu Limited
Thompson Gregory
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