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Method for measuring the thermal conductivity of thin-film composite materials

IP.com Disclosure Number: IPCOM000012937D
Publication Date: 2003-Jun-11
Document File: 4 page(s) / 449K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for measuring the thermal conductivity of thin-film composite materials. Benefits include improved functionality and improved support for future technologies.

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Method for measuring the thermal conductivity of thin-film composite materials

Disclosed is a method for measuring the thermal conductivity of thin-film composite materials.  Benefits include improved functionality and improved support for future technologies.

Background

      Thermal interface materials, (see Figure 1), are comprised of two or more materials. In the case of a new class of thermal interface materials, a polymer material holds carbon nanotubes. The thermal conductivity of the polymer is several orders of magnitude below that of the nanotubes. In terms of size, the nanotubes are on the order of nanometers, far below the resolution of conventional measurement devices. If a surface temperature average is used to determine the thermal conductivity of the bulk sample, the contributions of the individual tubes may not be accounted for. One method of determining the differences in temperature that exist on the surface of a composite is scanning thermal microscopy (ScThM), which is capable of nanometer spatial resolution (see Figure 2).

      The thermal conductivity of thin films is conventionally measured by a variety of techniques. Most involve either a laser flash method or a contact conductance method to report thermal diffusivity, which must be converted into thermal conductivity. The specific heat of a particular material must be known before usage, which is not typically available for composite materials. The temperature field of a composite material is a strong function of the orientation of the material components and the bulk. The averaging approach taken in current setups often obscures the real temperature field. Measurement devices conventionally used in the determination of thermal conductivity lack the spatial resolution required to resolve the correct temperature field.

General description

      The disclosed method is an apparatus for measuring thermal conductivity of thin-film composite thermal interface materials (TIM). The key elements of the method include:

•             Constant-temperature fluid loop that transfers heat to the bottom of the material sample

•             ScThM that measures the topology and temperature of the surface and the ambient temperature

•             Calculation of the amount of heat being transferred through the sample using correlations for natural convection

•             Calculation of the thermal conductivity of the sample by dividing the amount of heat by k=qsample

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to measuring the thermal conductivity of thin film composite TIMs

•             Improved functionality due to measuring thermal conductivity directly from a thin film of composite material

•             Improved support for future technologies due to providi...