Background

There is a wide consencus in the microelectronics industry that current thermal interface materials constitute the main bottleneck hindering a reduction of junction to ambient thermal resistance to future required levels (< 0.2 K/W). As a consequence, significant research effort is devoted to the development of new thermal interface materials capable of meeting future demands on thermal performance and reliability. Among numerous proposed material types, interpenetrating phase composites have been identified as a promising composite structure for future thermal interface materials.

Purpose

The purpose of the project is to fabricate and characterize the fundamental thermal and mechanical aspects of a new class of interpenetrating phase composites for thermal interface material applications in electronic packaging. The composite will be based on a porous reinforcing continuous structure of carbon nanofibers pressure infiltrated with a metal phase. High thermal conductivity and low contact resistance is provided by the metal phase, while the carbon nanofiber reinforcement defines geometry and reduces solidification shrinkage during assembly.

The carbon nanofiber reinforcement will be fabricated by electrospinning of polyacrylonitrile, followed by subsequent oxidization and pyrolysis. The project requires in-depth studies of process parameters in all three steps. Consolidation of the final composite structure by pressure assisted infiltration of the metal phase will be carried out with existing methods, followed by mechanical and thermal characterization.

Objectives

The main objectives are:

• Develop electrospinning processes for polyacrylonitrile based on results reported in literature
• Fabricate carbon nanofibers by oxidization and pyrolysis of electrospun polyacrylonitrile and related process and material studies
• Consolidate final composites using available equipment and characterize thermal and mechanical properties

With minor alterations, the project can be done either as a 30 or 60 credit points thesis work. Suitable backgrounds for applicants include engineering physics, chemistry, material science and mechanical engineering.