Abstract
There is a need for next-generation, high-performance power electronic packages and systems utilizing wide-band-gap devices to operate at high temperatures in automotive and electricity transmission applications. Sn-3.5Ag solder is a candidate for use in such packages with potential maximum operating temperatures of about 200 C. However, there is a need to understand the thermal cycling reliability of Sn-3.5Ag solders subject to such high-temperature operating conditions. The results of a study on the damage evolution occurring in large-area Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates with Au/Ni-P metallization subject to thermal cycling between 200 C and 5 C are presented in this paper. Interface structure evolution and damage accumulation were followed using high-resolution X-ray radiography, cross-sectional optical and scanning electron microscopies, and X-ray microanalysis in these joints for up to 3000 thermal cycles. Optical and scanning electron microscopy results showed that the stresses introduced by the thermal cycling result in cracking and delamination at the copper-intermetallic compound interface. X-ray microanalysis showed that stresses due to thermal cycling resulted in physical cracking and breakdown of the Ni-P barrier layer, facilitating Cu-Sn interdiffusion. This interdiffusion resulted in the formation of Cu-Sn intermetallic compounds underneath the Ni-P layer, subsequently leading to delamination between the Ni-rich layer and Cu-Sn intermetallic compounds.
Original language | English |
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Pages (from-to) | 240-248 |
Number of pages | 9 |
Journal | Journal of Electronic Materials |
Volume | 42 |
Issue number | 2 |
DOIs | |
State | Published - Feb 2013 |
Funding
The authors wish to acknowledge Jackie Mayotte for metallography, and Dr. Dane Wilson and Dr. Glenn Romanoski for review of the manuscript. This research was sponsored by the U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability-Power Electronics Program under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. Partial funding for the thermal cycling study was provided by the Propulsion Materials Program, Office of Vehicle Technologies. Partial funding for the SEM characterization of the joints was provided by ORNL’s High Temperature Materials Laboratory User Program sponsored by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, U.S. Department of Energy.
Funders | Funder number |
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ORNL’s High Temperature Materials Laboratory | |
U.S. Department of Energy | DE-AC05-00OR22725 |
Office of Energy Efficiency and Renewable Energy | |
Vehicle Technologies Office |
Keywords
- High-temperature packaging
- X-ray imaging
- creep
- fatigue
- intermetallic compounds
- power electronics