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Method for a heatsink using composite materials with non-isotropic thermal conductivity

IP.com Disclosure Number: IPCOM000010021D
Publication Date: 2002-Oct-09
Document File: 4 page(s) / 78K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a heatsink using composite materials with nonisotropic thermal conductivity. Benefits include improved thermal performance.

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Method for a heatsink using composite materials with non-isotropic thermal conductivity

Disclosed is a method for a heatsink using composite materials with nonisotropic thermal conductivity. Benefits include improved thermal performance.

Background

      Because power dissipation of electronic device is increasing, a material with higher thermal conductivity is required to increase the heatsink efficiency. Conventionally, this problem is solved by using a highly thermal-conductive carbon/graphite fiber as a heatsink material. Solutions include extruded (see Figure 1) and cross-cut (see Figure 2) heatsink designs. The materials used for heatsink manufacture are typically aluminum and copper.

              Carbon fiber is 1.5X to 2.5X of copper (Cu) thermal conductivity along the fiber direction. However, the thermal conductivity in the radial direction of the fiber is very poor (see Figure 3).

Introducing composite materials with nonisotropic thermal conductivity (such as carbon fiber or graphite fiber) on the current heatsink designs has limitations. The texture in the heatsink indicates the fiber direction (typically, the vertical direction). The heatsink base cannot effectively spread the heat from the electronic device in the horizontal direction due to the poor thermal conduction in the radial direction of the composite fibers. Only the heat fins near the electronic device are heated. The heat fins away from the electronic device remain cool and ineffective. The heat can be dissipated to the external ambient environment by the fin tips and the top of heatsink base only (as shown by small arrows in the figure). The vertical fin walls cannot effectively conduct heat to the external ambient due to the poor thermal conduction in the radial direction of the composite fibers. Effectiveness is not improved because the heatsink design does not fully accommodate the characteristics of nonisotropic thermal conduction. 

General description

              The disclosed method is a copper heat spreader bonded to the composite heatsink base to accommodate the pure heat spreading effect of the heatsink base made of carbon fiber. The heat is dissipated so that it can effectively reach the heat fins. They have a wave shape rather than a square or rectangular shape so tha...