Lehigh University
Lehigh University


Royal Thai Scholar prepares to finish decorated career as PSE grad student

From those to whom much is given, much is expected.

The adage is especially apt for students who receive the Royal Thai Scholarship, the top science and engineering award given by the government of Thailand.

Orasa Khayankarn was 13 years old when she was chosen in a national competition in Thailand to become a Royal Thai Scholar. Following her education in special schools, she completed a B.S. and M.S. from Thailand's Prince of Songkha University and Chulalongkorn University and enrolled in Lehigh's polymer science and engineering (PSE) graduate program.

Today, Orasa has made a name for herself by studying organic chemical compounds that promote adhesion inside the tiny packaging units that house microelectronic and optoelectronic devices.

While completing an M.S. in PSE in 2002 and a Ph.D. in 2004, Orasa won two first-place poster awards from the Lehigh Valley chapter of the International Microelectronics and Packaging Society, and a research award from the Society of Plastics Engineers.

Articles co-written by Orasa have been published in the Journal of Adhesion and the Journal of Applied Polymer Science. Orasa has given presentations in North and South Carolina and Massachusetts, and she has collaborated with Dow Chemical Co. since 2001.

In her research at Lehigh, Orasa studied the heat and humidity that can cause a process known as aging, or weakening of the bond at the interface of the glass casing and epoxy adhesive in microelectronic packaging.

After preparing small "sandwich" samples containing a "filling" of epoxy surrounded by two glass sheets, she placed them in a chamber heated to 85 degrees C. with a relative humidity of 85 percent. She varied the "aging times" from several hours to several weeks or more, and also varied the chemistry of the glass-epoxy interface, and measured the adhesive strength of the interface bond.

"We made the temperature and humidity more severe than real-life conditions," she says, "in order to speed up the aging process and determine more quickly how strong the interface was."

Orasa focused particularly on silane, a silicon compound that promotes adhesion by forming a chemical bond between the glass surface and the epoxy resin. She found that glass treated with silane resisted hygrothermal (moisture and heat) aging much more effectively than untreated glass.

Orasa had access to Lehigh's internationally renowned electron microscopy and spectroscopy facilities, including the x-ray photo-electron spectroscopy instrument, Fourier Transform Infrared Spectroscopy and nuclear magnetic resonance.

"These instruments are not found in many places because they are expensive and difficult to maintain," says Orasa. "They give very good information about the chemical composition of a surface, the strength of molecular bonds on a surface, and where cracks are beginning."

Orasa found the professors in the PSE program to be quite good, especially Prof. Ray Pearson (materials science and engineering), her adviser, and Prof. Leslie Sperling (chemical engineering), who has written 14 books.

After completing her Ph.D., Orasa returned to Thailand to work in the polymers area of the Department of Science Service in Bangkok, one of Thailand's national laboratories.

Posted on Sunday, August 01, 2004

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