Heat sink grounded to a grounded package lid

Details Heat sink grounded to a grounded package lid Heat sink grounded to a grounded package lid

2001-01-19

2003-01-28

Schuberg, Darren (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S704000, C361S707000, C257S706000, C174S015100

Reexamination Certificate

active

06512675

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the packaging of an integrated circuit assembly and, more particularly, to a heat sink and package lid arrangement for an integrated circuit package.
DESCRIPTION OF RELATED ART
Package lids and heat sinks are generally used in integrated circuit assemblies. One such integrated circuit assembly is shown in FIG.
1
. In
FIG. 1
, there is a system board
10
to which an integrated circuit package
12
is mounted. The integrated circuit package
12
includes an integrated circuit die
14
. A package lid
16
(or heat spreader) is adhered to an upper surface of the package
12
to protect the integrated circuit die
14
and to act as an electromagnetic interference shield. The package lid
16
often serves to spread the heat generated by the integrated circuit die
14
over a larger area. Mounted to the package lid
16
is a heat sink
18
, which is thermally coupled to the package lid
16
and serves to dissipate heat. In many conventional integrated circuit assemblies, the heat sink
18
is mounted to the lid
16
by a systems manufacturer.
As shown in
FIG. 1
, the system board
10
is equipped with an electrically conductive ground lead
20
and at least one more electrically conductive lead
22
, which includes a connection to a power supply (not shown). In one conventional system, the ground lead
20
is electrically coupled to a conductive surface on the package
12
with an electrically conductive wire
24
or the like. Another electrically conductive lead
26
also extends from the system board to the electrically conductive surface on the package
12
.
Alternatively, the heat sink
18
itself may be grounded to the system board
10
with an electrically conductive wire or the like. With this alternative, as shown in
FIG. 1
, a wire travels from the heat sink to the system board. As noted above, heat sinks are placed on the package lid by a systems manufacturer who may obtain heat sinks from a variety of different manufacturers. The heat sinks produced by varying manufactures may have differing sizes and shapes. As a result, system boards must have different sockets so that the different sized and shaped heat sinks can be grounded.
There are problems, however, with conventional integrated circuit package assemblies. One such problem is that, because heat sinks are normally placed on the package lid after the manufacturer of the integrated circuit package assembly has delivered the package assembly to the system manufacturer, different system board socket positions are needed for different heat sinks due to differing sizes and shapes. Another problem involves the need to ground the heat sink to the system ground, which involves wiring the heat sink to the system ground after the system board has been manufactured, thereby adding an additional step in the manufacturing process. Also, the connectors that connect the heat sink to the system ground are exposed, which can lead to breakage.
SUMMARY OF THE INVENTION
There is a need for a heat sink and package lid assembly that improves the assembly of the heat sink and package lid and reduces the risk of breakage.
These and other needs are met by embodiments of the present invention which provides an integrated circuit package assembly having a package board, an electrically grounded package lid mounted to the package board, and a heat sink mounted to the package lid and grounded only through the package lid.
The grounding of a package lid and mounting of a heat sink to the grounded package lid so as to ground the heat sink only through the package lid reduces the possibility of breakage as there are no exposed wires connecting the heat sink and the system board. Also, assembly is improved as the unit is more readily connectable to a system board. Moreover, the inventive heat sink-package lid assembly provides for a modular assembly that reduces manufacturing costs and reduces the number of parts.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.


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