Bongtae Han Delivers Keynote at International Congress

ME Associate Professor Bongtae Han delivered a Keynote Address at the Fifth International Congress on Thermal Stresses and Related Topics, held June 8-11, 2003, on the campus of Virginia Tech in Blacksburg, Va.

Professor Han's address was entitled "Thermal Stresses in Microelectronics Subassemblies: Quantitative Characterization using Photomechanics Methods." The abstract follows:

A microelectronics subassembly is comprised of various conducting and insulating materials, which have different coefficients of thermal expansions. When the chip is powered so that the package is subjected to a temperature change, each material deforms at a different rate. This non-uniform CTE distribution produces thermally induced mechanical stresses within the package assembly. As the components and structures involved in high-end microelectronics devices are made smaller, the thermal gradient increases and the strain concentrations become more serious. Accordingly, advanced experimental techniques are highly demanded to provide accurate solutions for deformation studies of microelectronics devices.

In recent years, numerous optical methods for deformation measurements have matured and emerged as important engineering tools. More recently, several methods have been applied to thermal deformation analyses of microelectronics subassemblies. They include moiré interferometry, microscopic moiré interferometry, Twyman/Green interferometry, Far infrared Fizeau interferometry, shadow moiré. This paper reviews features and recent developments of the methods, and illustrates applications to diverse problems encountered in microelectronics product development.

Published June 8, 2003