Characterization of Epoxy-Functionalized Silsesquioxanes as Potential Underfill Encapsulants

Richard Laine

C.R. SFMWWWWZRML E.K. Lin (1998)

in Organic/Inorganic Hybrid Materials, MRS Symp. Ser., 519:15-20, R.M. Laine, C. Sanchez, C.J. Brinker, E. Giannelis eds..

In electronics packaging, underfill encapsulants are needed to improve package reliability in flip-chip devices. The underfill generally consists of an epoxy resin highly filled with silica particles and is designed to reduce the stress arising from the difference in the thermal expansion between the solder bumps and the substrate. Currently, concerns about the flow of the silica particles and surface phenomena are arising as electronics packages reduce in size. Newly developed epoxy-functionalized octameric silsesquioxanes provide an intriguing alternative to current formulations. These single-phase inorganic/organic hybrid materials may have properties similar to filled materials without the complications from the rheology of filled materials. The physical properties of the functionalized silsesquioxanes are measured with respect to the critical parameters for underfill materials. Measurements of properties such as the coefficient of thermal expansion and density are performed to evaluate the suitability of these materials as potential underfill encapsulants.