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Method for a high-performance foam heatsink

IP.com Disclosure Number: IPCOM000138134D
Publication Date: 2006-Jul-10
Document File: 5 page(s) / 258K

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The IP.com Prior Art Database


Disclosed is a method for a high-performance foam heatsink. Benefits include improved functionality and improved thermal performance.

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Method for a high-performance foam heatsink

Disclosed is a method for a high-performance foam heatsink. Benefits include improved functionality and improved thermal performance.


      Heat generation rates in microelectronic chips and components continue to increase as sizes decrease and performance increases. Because the small size provides a small surface area for heat dissipation, thermal performance is becoming critical. Additionally, a continuing increase in current densities from advanced chips and components is expected to exponentially increase.

      A conventional solution to increased heating is the use of a copper or aluminum solid heat slug attached to the die for transfer of generated heat. Alternatively, liquid cooling is widely used in the form of miniature heat pipes that are a part of nearly all laptop computers. However, with decreasing package size and increasing current densities, these conventional techniques are becoming restricted to their limits. An improved solution is required.

      Foam materials have a combination of characteristics that make them attractive for a number of engineering applications, including lightweight structural sandwich panels, energy absorption devices, and heatsinks. Aluminum (Al) foams are the most common, though many others are available including:

•     Nickel  (Ni)

•     Copper (Cu)

•     Zinc

•     Steel

•     Graphite

      Open cell foams can be used for heat dissipation due to their high thermal conductivity, high internal surface area, and the connectivity of the voids. They enable a cooling fluid (water or gas) to flow through and absorb heat. Some graphite foams have a conductivity comparable to pure solid aluminum (~180 W/m×K) without any cooling scheme (the presence of liquid).

      Several foam types are available. They can be either open cell or closed cell with a significant variation in the number of pores per inch (ppi), pore size, and pore distribution. The surface area density (total area over the foam volume) is an important parameter for heat-exchange systems. It is associated with the foam type and characteristics, such as cell size and relative density. The surface area density can be calculated using the following equation:

aA » r1/2                                                                                                                          [1]

      A rough experimental estimation of a foam surface area in comparison with its solid form is obtainable using the following procedure:

1.   Insert foam in a vacuum furnace.
2.   Deposit a metal at high temperature with a length of the same material wire.

3.   After a period of...