Chin C. Lee of University of California, Irvine

The silver-indium (Ag-In) binary system is reviewed. This system has never been used in electronic industries except In-3%Ag eutectic for bonding laser diode chips. It was chosen for our packaging process development because of its forward looking possibilities that other systems do not possess. Next, conventional die-attach materials and fluxing action in soldering processes is briefly presented. Several processes dealing with tin oxides are mentioned. Our fluxless bonding is then introduced. Four fluxless bonding designs using the Ag-In system are reported. The joints were made at 250 degrees C. All joints produced have melting temperature higher than 700°C. Samples of the third design survived 5,000 thermal cycles between -40 to +200°C. The fourth design survived storage at 350°C for 200 hours.

The joints reported above contain pure Ag, solid solution (Ag), and/or Ag₂In intermetallic compound. To find out the mechanical properties of these materials, ingots have been grown in house. ASTM tensile test (TT) samples are prepared. (Ag)-19In TT samples exhibit superior tensile properties compared to pure Ag. Here (Ag)-19In means solid solution with 19 at. % In. The hardness and fracture toughness of Ag₂In are measured. Reaction experiments with sulfur (S) vapor shows that the reaction rate with (Ag)-19In is much lower than that with pure Ag and the commercial available Agentium Ag. It seems that (Ag)-19In has the superior anti-tarnishing property that the metallurgy community has been looking for several centuries.

Ag has superior physical properties. The challenge in its electronic, jewelry,  and optical applications is tarnishing. It reacts easily with S and H₂S to form Ag₂S which is black and fragile. Our preliminary results on the properties of (Ag)-xxIn seem to indicate that (Ag) solid solution might be an answer.

Biography:

Chin C. Lee was born in Taiwan. He received B.E. and M.S. degrees in electronics from Chiao-Tung University, Taiwan, and Ph.D. degree in electrical engineering from Carnegie-Mellon University.

He is a professor of electrical engineering and computer science at the University of California, Irvine, where he also serves as the Director and Graduate Advisor of the school-wide Materials and Manufacturing Technology (MMT) graduate program. His research activities include acoustic waves, bonding technology, electromagnetic theory, electronic packaging, metallurgy, microwave devices, music, optoelectronics, semiconductor devices, and thermal analysis and design. He has co-authored 5 book chapters and near 300 research papers.

Chin C. Lee is a Life Fellow of IEEE (Institute of Electric and Electronic Engineers, Inc.), a Fellow of Photonics Society of Chinese-Americans, and a life member of Tau Beta Pi. He has served as an associate editor of IEEE Trans. on Components, Packaging and Manufacturing Technology (CPMT) for 23 years. Since 1998, he has been on the Program Committee of IEEE Electronic Components and Technology Conference (ECTC) and served as the Chair of Materials and Processing sub-committee for 4 yours. He also served as the Chair of CPMT Society Technical Committee on Material and Processes in 2013 and 2014.

He received the Best Paper Award for "Diagnosis of hybrid microelectronics using transmission acoustic microscopy" in 1979 IEEE Reliability Physics Symposium, the 2007 IEEE-CPMT Exceptional Technical Achievement Award, and the 2012 IEEE-CMPT Electronics Manufacturing Technology Award.

Email:

Address:Electrical Engineering and Manufacturing Technology, University of California, Irvine, California, United States, 92697-2660

Chin C. Lee of University of California, Irvine

Biography:

Email:

Address:Irvine, California, United States