This research seeks to characterize the micro-mechanical behavior of Sn-Ag-Cu solder bumps/joints generated by fine feature flip chip fabrication and assembly processes. The bumps used for characterization were produced by stencil deposition of solder paste onto an electroless Nickel UBM, followed by a bump-forming reflow soldering process and the final assembly joints were then achieved by a subsequent reflow of die onto a fine feature Printed Circuit Board (PCB). The bumps and joints were aged at either 80°C or 150°C for up to 1.5 months and then analyzed by means of micro-shear testing and nano-indentation techniques. The shear test of the aged bumps showed a slight increase in shear strength after an initial period of aging (∼ 50h) as compared to as-manufactured bumps, but a decrease after longer aging (e.g. 440 h). A brittle Ag3Sn phase formed as large lamellae in the solder and along the interface between the Cu on the PCB during the initial aging, and is attributed to the increase of shear strength, along with the refinement of the bump microstructure. However, as the time of aging extended, the solder bumps were softened due to grain growth and re-crystallization. It was found that the formation of brittle phases in the solder and along the interfaces caused localized stress concentration, which can significantly affect joint reliability. In addition, Nano-testing identified a lamellar Au-rich structure, formed in the solder and interface of the solder/PCB in the joints after the aging process. These are believed to be detrimental to joint reliability.
Skip Nav Destination
ASME 2003 International Electronic Packaging Technical Conference and Exhibition
July 6–11, 2003
Maui, Hawaii, USA
Conference Sponsors:
- Electronic and Photonic Packaging Division
ISBN:
0-7918-3690-8
PROCEEDINGS PAPER
Analysis of the Micro-Mechanical Properties in Aged Lead-Free, Fine Pitch Flip Chip Joints
Changqing Liu,
Changqing Liu
Loughborough University, Loughborough, UK
Search for other works by this author on:
Paul Conway,
Paul Conway
Loughborough University, Loughborough, UK
Search for other works by this author on:
Dezhi Li,
Dezhi Li
Loughborough University, Loughborough, UK
Search for other works by this author on:
Michael Hendriksen
Michael Hendriksen
Celestica, Ltd., Kidsgrove, Stoke-on-Trent, Staffordshire, UK
Search for other works by this author on:
Changqing Liu
Loughborough University, Loughborough, UK
Paul Conway
Loughborough University, Loughborough, UK
Dezhi Li
Loughborough University, Loughborough, UK
Michael Hendriksen
Celestica, Ltd., Kidsgrove, Stoke-on-Trent, Staffordshire, UK
Paper No:
IPACK2003-35130, pp. 147-153; 7 pages
Published Online:
January 5, 2009
Citation
Liu, C, Conway, P, Li, D, & Hendriksen, M. "Analysis of the Micro-Mechanical Properties in Aged Lead-Free, Fine Pitch Flip Chip Joints." Proceedings of the ASME 2003 International Electronic Packaging Technical Conference and Exhibition. 2003 International Electronic Packaging Technical Conference and Exhibition, Volume 1. Maui, Hawaii, USA. July 6–11, 2003. pp. 147-153. ASME. https://doi.org/10.1115/IPACK2003-35130
Download citation file:
2
Views
Related Proceedings Papers
Related Articles
Analysis of the Micro-Mechanical Properties in Aged Lead-Free, Fine Pitch Flip Chip Joints
J. Electron. Packag (September,2004)
Correlation Between the Mechanical Strength and Curing Condition of No-Flow Flip Chip Assemblies
J. Electron. Packag (December,2002)
Flip-Chip Ball Grid Array Lead-Free Solder Joint Under Reliability Test
J. Electron. Packag (December,2005)
Related Chapters
Package-to-Board Interconnection
Essentials of Electronic Packaging: A Multidisciplinary Approach
A Dependable Answer
Hot Air Rises and Heat Sinks: Everything You Know about Cooling Electronics Is Wrong
Research on Strengthening Mechanism of Plant Root in Slope Protection
Geological Engineering: Proceedings of the 1 st International Conference (ICGE 2007)