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Extrusion Method for the Alignment of Graphitic Structures for Chipstack Cooling Disclosure Number: IPCOM000213542D
Publication Date: 2011-Dec-20
Document File: 2 page(s) / 45K

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The Prior Art Database


Disclosed is an extrusion method to improve 3D chipstack cooling through the alignment of graphitic structures in a thermal interface material.

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Extrusion Method for the Alignment of Graphitic Structures for Chipstack Cooling

A major problem with 3D chip stacks is heat dissipation from the inner chips. One existing approach utilizes carbon nanotubes (CNTs) dispersed randomly in a thermal interface material (TIM). However, in this application the CNTs are randomly oriented in the TIM. CNTs and other thermally conductive carbon structures exhibit anisotropic thermal conductivity (TC), such that the TC is orders of magnitude greater along one axis. Random distribution of the CNTs does not maximize the thermal conductivity (TC) of the TIM. Recently, concepts have been explored on the alignment of carbon structures which allows for 3D chip stacks to have aligned CNTs or graphite nanofibers (GNFs) in the xy plane, such that heat may be brought to the edges of the stack. However, in all of these concepts, the polymeric matrix when the alignment would occur is very viscous; this would make alignment difficult. Here we disclose a method for aligning graphitic structures within the TIM directly as the TIM is applied to the substrate.

    Graphitic structures are mixed in a base polymer and extruded through a convergent nozzle, allowing for the graphitic structures to become tightly packed and automatically aligned. The GNF-containing TIM is deposited directly on the substrate (chip surface) resulting in properly aligned GNFs in the desired configuration. A similar extrusion procedure has been described.[*] In this reference, CNTs, GNFs, or other graphitic structures are mixed into a solvent, producing a thick paste. The solvent could consist (but not be limited to) water, methanol, or other organic liquids. The resulting paste is fed int...