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High Thermally Conductive Electrically Insulative Filler Material for Thermal Interface Materials

IP.com Disclosure Number: IPCOM000244134D
Publication Date: 2015-Nov-12
Document File: 7 page(s) / 176K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a thermal interface material grease that has high thermal conductivity and little to no electrical conductivity.

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This is the abbreviated version, containing approximately 46% of the total text.

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High Thermally Conductive Electrically Insulative Filler Material for Thermal Interface Materials

The increasing demand for high-performance computing has led to an increase in device operating temperatures with heat fluxes in excess of 100 W/cm. [1] This increase in operating temperature creates significant thermal management challenges as well as issues with device reliability and performance. Normal thermal management of devices is handled by a thermal interface material (TIM). Here, the TIM can be a pad or grease. In thermal greases, a thermally conductive filler is used to pull heat away from the device being cooled and transfer that heat to a heat sink or cold plate. Typical filler materials would be alumina, BN, CNTs, etc. Thermal conductivity is the quantified ability of any material to transfer heat. The thermal conductivity of the interface material has a significant impact on its thermal performance. The higher the thermal conductivity, the more efficient the material is at transferring heat. Materials that have a lower thermal conductivity are less efficient at transferring heat, causing a higher temperature differential to exist across the interface. To overcome this less efficient heat transfer, a better cooling solution (typically, a more costly solution) must be used to achieve the desired heat dissipation. In addition to the desire to have high thermal conductivity, low electrical conductivity is highly desired. Some metal-based TIM compounds are electrically conductive, whereas ceramic-based compounds are typically not. Manufacturers produce metal-based compounds with low electrical conductivity, but some of these materials are not completely electrically inert. Metal-based thermal compounds are not hazardous to the processor die itself, but other elements on the processor or motherboard can be at risk if they become contaminated by the compound. For this reason, AMD does not recommend the use of electrically conductive thermal interface material. [2]

    The goal of this invention is to provide a TIM grease that has high thermal conductivity and little to no electrical conductivity. The core idea of the invention is as follows: high thermally conductivity material is encapsulated in an electrically insulating material. The electrically isolated, thermally conductive filler material is then blended with standard thermal grease-based polymers for use as a thermal grease. The invention works as follows:

    Metal nanoparticles, such as copper nanoparticles (TC = 401 W/m K, bulk copper), are placed in a solution containing (3-aminopropyl)trimethoxysilane and allowed to interact with the copper surface (see Figure 1 below). Next, the modified copper nanoparticles are condensed with sodium silicate to form an insulative silica layer around the copper particle (see Figure 2 below). Next, the insulated copper particles are blended at high weight percents (even above the percolation threshold of the copper nanoparticles) into P...