Adam Kohn



Download Full Text (1.8 MB)


2010 People's Choice

Status of Main Author

Undergraduate Student


Material Science and Engineering


Pearson, Raymond

Publication Date



Epoxy resins filled with silica are used in a wide array of applications. When used in microelectronic packaging, chiefly as an underfill encaplsulant, it is critical that such epoxy resins possess low viscosity as well as high fracture toughness. Traditionally, micron-size silica fillers are used but there is much interest in the use of nanometer size fillers as the feature size on silicon chips decreases. In this study, the rheological behavior of an epoxy resin containing nanosilica fillers was characterized in steady state shear using a Rheometerics ARES rheometer equipped with a Couette fixture. Two types of nanosilica particles were examined as potential fillers(22nm and 168nm in diameter) as well as mixtures of both. Interestingly, the unimodal formulations exhibited reduced viscosities larger than those predicted from Einstein's equation, thus suggesting significant interactions between particles. Note that shear rate studies did not reveal the presence of a yield stress nor structure formation. Bimodal mixtures of nanosilica were also explored as a possible means to reduce the viscosity for a given nanosilica content. Initial results look promising even though the nanosilica content is lower than what is traditionally used in these systems.

Author Notes

Adam Kohn, from Emerson, New Jersey, is a Junior Materials Science and Engineering major at Lehigh University with a minor in Japanese. For the past two years, he has conducted research in Lehigh's Center for Polymers Science and Engineering. His primary research focused on analyzing the influence of tri-block co-polymers on viscous properties of resin materials. This project resulted in a personal research project for the past two semesters on the rheological behavior of resin materials. After graduating from Lehigh, Adam intends to attend grad school for either Materials Engineering or Polymers Engineering. In addition to lab work, Adam is also a Gryphon in a sophomore residence hall, President of the Residence Hall Association, Secretary of the Student Materials Society, and a member of the Council of Student Presidents. He likes to spend his free time running on the many hills that Lehigh has to offer!

Behavior of Nanosilica Filled Epoxies