High Performance Thermal Interface Materials Using PDMS/Low Melting Point Alloy Composite

In 1965,Gordon Moore,the co-founder of Intel described in the 35^th anniversary issue of Electronics magazine the doubling every year in the number of components per integrated circuit.In 1975,he revised his forecast to doubling every 2 years.Since then,his prediction proved accurate and has been used in the semiconductor industry to guide long-term planning and to set targets for research and development.This endless miniaturization of components led to the development of nanotechnology and the need of better thermal management in integrated circuits used in every electronic device today.In order to prevent the failure of performance,cooling has therefore become one major challenge.Air convection cooling is still the most widely used method in the industry,nevertheless,researchers in the past several years have been investigating new ways to improve the cooling of integrated circuits.Thermal interface materials(TIMs)are one of the solution researchers have been investigating.The idea here is to use a material that will be set between a part that has to be cooled and the cooler.The material used should have a high intrinsic thermal conductivity and have good mechanical characteristics as well.The material has to be flexible so that it can fill the voids and the pockets of air at the interface(because air has low thermal conductivity).To do so,researchers tried in the recent years to fabricate a high flexible/light-weight and thin thermal conductive material by using conductive particles(usually metals)which fill a flexible matrix(usually polymers).The numbers of coupling possibilities between matrix and filler are infinite.Epoxy resins or silicon based polymers for the matrix are usually used.As for the fillers,graphene,boron nitride,carbon nanoparticles,carbon nanotubes have sparkled the interest of researchers.Our research was focused on the use of Low Melting Point Metals(LMPM)to fill a polydimethylsiloxane(PDMS)matrix to achieve the fabrication of a high thermally conductive composite material.LMPM are interesting as industrial wants simple and cheap ways to mass produce a component(the cost of fabricating carbon nanotubes or any other nanoparticles today are prohibitive for industrials).Furthermore,very few investigations on LMPM use in a PDMS polymer-matrix were carried,making my research a cutting-edge scientific investigation.We report two different and repeatable fabrication methods of a PDMS/LMPM composite materials,achieving respectively a thermal conductivity of 1.2-5.8 W/(m.K)at 80-90 wt.%loading and3-4 W/(m.K)at 20-30 wt.%loading.The measurements were carried with the widely accepted laser flash analysis method.