Archive ScienceWatch



King-Ning Tu talks with and answers a few questions about this month's Fast Moving Front in the field of Materials Science.
Tu Article: Six cases of reliability study of Pb-free solder joints in electronic packaging technology
Authors: Zeng, K;Tu , KN
Journal: MAT SCI ENG R, 38 (2): 55-105 JUN 14 2002
Addresses: Univ Calif Los Angeles, Dept Mat Sci & Engn, Los Angeles, CA 90095 USA.
Univ Calif Los Angeles, Dept Mat Sci & Engn, Los Angeles, CA 90095 USA.


Why do you think your paper is highly cited?

The report is about failures in Pb-free solder joints used in electronic consumer products. Because there is a ban on using Pb-based solders by the Congress of the EU, the electronics industry has had to apply Pb-free solders to their products without undertaking enough study about reliability. A high rate of failure is found, for example, due to electromigration.

Does it describe a new discovery, methodology, or synthesis of knowledge?

Due to the trend in miniaturization and the increase in functionality, the reliability of solder joint in microelectronic devices is of concern, even for wireless and handheld consumer electronic products. A new discovery is that the current crowding in flip-chip solder joints has induced a fast and new mode of failure that was not known before. The methodology used to study electromigration in flip-chip technology is presented, with knowledge and analysis provided.

Would you summarize the significance of your paper in layman's terms?

While Pb-free solder has been used in plumbing, until recently, it had not been found in electronic consumer products. Our paper reports on what are the yield and reliability problems when Pb-free solder is being used in electronic consumer products.

How did you become involved in this research and were there any particular problems encountered along the way?

I have worked on solder materials for over 40 years, finishing my Ph.D. thesis on Pb-Sn alloys in 1968. Since then, I have remained keenly interested in solder alloys and their applications.

Where do you see your research leading in the future?

The trend in the electronics industry is toward the use of smaller and smaller solder joints. The reliability problems will become more serious and they will not easily go away. I shall try to bring more scientific understanding to the problem in electronic packaging technology.

Do you foresee any social or political implications for your research?

Since Pb-based solder is toxic to health, our research on Pb-free solder will benefit society.

King-Ning Tu, Ph.D.
Department of Materials Science and Engineering
University of California, Los Angeles
Los Angeles, CA, USA

Keywords: Pb-free solder joints, Pb-free solder, flip-chip solder joints, electromigration, flip-chip technology flip-chip solder joints, Pb-Sn alloys


2008 : May 2008 - Fast Moving Fronts : King-Ning Tu