Serpentine, slit fin heat sink device

Details Serpentine, slit fin heat sink device Serpentine, slit fin heat sink device

2002-03-14

2003-07-08

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C165S080300, C165S121000, C165S185000, C257S722000, C361S704000, C415S178000

Reexamination Certificate

active

06590770

ABSTRACT:

FIELD OF THE INVENTION
This device relates to heat sinks, and more particular to improved fins for heat sink devices that include a fan for cooling an electronic component such as an integrated circuit chip, a CPU chip, a large scale chip package, or a very large scale chip package, especially an impingement airflow fan.
BACKGROUND OF THE INVENTION
Heat sink devices that include a base plate having one surface adapted for receiving heat from an electronic device and another surface for mounting a heat conductive, serpentine fin, and an impingement airflow fan for directing an air flow perpendicular to the surface of the plate on which the fin is mounted are well known. Examples of such heat sink devices are disclosed in U.S. Pat. Nos. 4,753,290, 5,251,101, 5,299,632, 5,494,098, 5,597,034, 6,109,341, and 6,135,200. Heat sink devices are also known that utilize a fan to direct an airflow parallel to the surface of the plate on which the fin is mounted. While at least some of these devices may work well for their intended purpose, there is always room for improvement.
SUMMARY OF THE INVENTION
It is the primary object of the invention to provide a new and improved fin for a heat sink device.
It is another object of the invention to provide a new and improved fin for a heat sink device including an impingement airflow fan.
In one form of the invention, an improvement is provided in a heat sink device for cooling an electronic component having a surface that rejects heat. The heat sink includes a plate having first and second surfaces, with the first surface configured to receive heat from the surface of the electronic component, and a fan spaced above the second surface to direct an air flow towards the second surface substantially perpendicularly to the second surface. The improvement includes a serpentine fin underlying the fan and bonded to the second surface. The fin is formed from a folded sheet of material having a thickness t. The fin includes a plurality of sidewalls extending substantially perpendicular to the second surface and joined to each other by bends formed in the sheet. Spaced slits are provided in each of the sidewalls extending substantially perpendicular to the second surface. Each of the sidewalls has a plurality of offsets sidewall portions, with each offset sidewall portions in the sidewall having a width W extending between a pair of the spaced slits in the sidewall and being offset from any adjacent offset sidewall portion in the sidewall by a gap G. Each of the offset sidewall portions has a length L perpendicular to the gap G.
In one form, the ratio of L/G is in the range of 23 to 100.
According to one aspect, the ratio of L/G is in the range of 30 to 40.
In one form, the offset sidewall portions in each sidewall are spaced from the offset sidewall portions in any adjacent sidewall by a fin pitch spacing p that is substantially equal to (2*G)+t.
In one aspect, the ratio of G/t is in the range of 2 to 6.
In one aspect, the thickness t is in the range of 0.004″ to 0.016″.
In accordance with one form, the fin has a total height H perpendicular to the second surface and the ratio of L/H is in the range of 0.7 to 0.95.
According to one aspect, the ratio of W/G is in the range of 2.5 to 10.
In one form, at least some of the offset sidewall portions include a rib formed therein extending substantially perpendicular to the second surface, the rib having a length that is at least equal to ½* L. The fin has a total height H perpendicular to the second surface and the ratio of L/H is in the range of 0.7 to 0.95. In one form, H is in the range of 0.75″ to 2.75″. In one form, G is in the range of 0.019″ to 0.039″, and in a highly preferred form, G is in the range of 0.022″ to 0.030″.
According to one aspect of the invention, an improvement is provided in a heat sink device for cooling an electronic component having a surface that rejects heat. The heat sink device includes a plate having first and second surfaces, with the first surface configured to receive heat rejected from the surface of the electronic component. The improvement includes a serpentine fin bonded to the second surface. The fin is formed from a folded sheet of material having a nominal thickness t, and includes a plurality of substantially parallel sidewalls extending substantially perpendicular to the second surface and joined to each other by bends formed in the sheet. Spaced slits are provided in each of the sidewalls extending substantially perpendicular to the second surface, and each sidewall has a plurality of offset sidewall portions, with each offset sidewall portion in the sidewall having a width W extending between a pair of the spaced slits formed in the sidewall and being offset from any adjacent offset sidewall portion in the sidewall by a gap G. The fin has a total height H perpendicular to the second surface, with H being in the range of 2″ to 4″. Each of the offset sidewall portions has a length L perpendicular to the gap G, and the ratio of L/H is in the range of 0.7 to 0.95. At least some of the offset sidewall portions include a rib formed therein extending substantially perpendicular to the second surface, and each of the ribs has a length that is at. least equal to ½*L. In one form, G is in the range of 0.19″ to 0.039″, and in a highly preferred form G is in the range of 0.022″ to 0.030″.
Other objects and advantages will become apparent from the following specification, including the drawings and appended claims.


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