Heat sink assembly and method

Details Heat sink assembly and method Heat sink assembly and method

2001-12-03

2003-07-08

Tolin, Gerald (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C029S890030, C024S296000, C257S719000

Reexamination Certificate

active

06590771

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat sink assembly and a method of assembling a heat sink to an electronic device. The invention particularly relates to a heat sink assembly that includes a clip which compresses a heat sink against an electronic device.
BACKGROUND
Electronic devices generate heat during operation. Thermal management refers to the ability to keep temperature-sensitive elements in an electronic device within a prescribed operating temperature.
Historically, electronic devices have been cooled by natural convection. The cases or packaging of the devices included strategically located openings (e.g., slots) that allow warm air to escape and cooler air to be drawn in.
The advent of high performance electronic devices, such as processors, now require more innovative thermal management. Each increase in processing speed and power generally carries a “cost” of increased heat generation such that natural convection is no longer sufficient to provide proper thermal management.
One common method of cooling electronic devices includes thermally coupling a heat sink to the package of the electronic device. A typical heat sink includes protrusions, such as fins or pins, which project from a body of the heat sink. The protrusions give the heat sink a larger surface area such that the heat sink dissipates a greater amount of thermal energy from the package into the surrounding environment. Heat sinks are fabricated from materials with high thermal conductivity in order to efficiently transfer thermal energy from the electronic device package.
The heat sinks are typically mounted to the electronic devices by using adhesives, screws, and/or bolts. Another common method uses one or more clips to secure a heat sink to an electronic device.
FIGS. 1-5
illustrate a prior art heat sink assembly
10
. Heat sink assembly
10
includes a heat sink
20
, clip
30
and electronic device
40
. Electronic device
40
is mounted to a frame, such as socket
50
. Socket
50
is attached to a substrate, such as printed circuit board
51
(see FIGS.
4
and
5
). Clip
30
compresses heat sink
20
against electronic device
40
and is typically in the form of a bent wire that includes two legs
32
and an elongated central portion
34
extending between the legs
32
. Each leg
32
is substantially perpendicular to central portion
34
and extends from central portion
34
in an opposite direction to the other leg
32
.
The central portion
34
of clip
30
extends between protrusions
28
on heat sink
20
. Clip
30
is assembled to socket
50
by maneuvering legs
32
under a pair of tabs
52
that are positioned on opposing sides of socket
50
. Legs
32
deflect elastically as they are moved under the tabs
52
generating a torque around the central portion
34
of clip
30
. The torque compresses the central portion
34
of clip
30
against heat sink
20
, which in turn compresses heat sink
20
against electronic device
40
. Compressing heat sink
20
against electronic device
40
reduces the thermal resistance between heat sink
20
and electronic device
40
.
FIG. 4
illustrates the proper position for heat sink
20
relative to electronic device
40
. Heat sink
20
includes a contact surface
21
that should be engaged with electronic device
40
over the entire contact surface
21
.
Mechanical shock or vibration during transportation and handling can cause heat sink
20
to shift relative to electronic device
40
.
FIG. 5
illustrates a case where heat sink
20
has shifted relative to electronic device
40
. A portion
22
of the contact surface
21
on heat sink
20
is no longer fully engaged with electronic device
40
. This situation is undesirable because anything less than full contact between the contact surface
21
on heat sink
20
and electronic device
40
renders heat sink
20
less effective in conducting thermal energy from electronic device
20
.
There is a need for a heat sink assembly and method that securely attaches a heat sink to an electronic device, especially when subjected to mechanical shock or vibration. The clips that are presently used to fasten heat sinks to electronic device packages are unable to adequately secure a heat sink to an electronic device package under such circumstances.


REFERENCES:
patent: 5386338 (1995-01-01), Jordan et al.
patent: 5448449 (1995-09-01), Bright et al.
patent: 6061239 (2000-05-01), Blomquist
patent: 6424530 (2002-07-01), Lee et al.
patent: 6449157 (2002-09-01), Chu

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