Title
Effects of process conditions on reliability, microstructure evolution and failure modes of SnAgCu solder joints
Abstract
In this study, microstructure evolution at intermetallic interfaces in SnAgCu solder joints of an area array component was investigated at various stages of a thermal cycling test. Failure modes of solder joints were analyzed to determine the effects of process conditions on crack propagation. Lead-free printed-circuit-board (PCB) assemblies were carried out using different foot print designs on PCBs, solder paste deposition volume and reflow profiles. Lead-free SnAgCu plastic-ball-grid-array (PBGA) components were assembled onto PCBs using SnAgCu solder paste. The assembled boards were subjected to the thermal cycling test (−40°C/+125°C), and crack initiation and crack propagation during the test were studied. Microstructure analysis and measurements of interface intermetallic growth were conducted using samples after 0, 1000, 2000 and 3000 thermal cycles. Failures were not found before 5700 thermal cycles and the characteristic lives of all solder joints produced using different process and design parameters were more than 7200 thermal cycles, indicating robust solder joints produced with a wide process window. In addition, the intermetallic interfaces were found to have Sn–Ni–Cu. The solder joints consisted of two Ag–Sn compounds exhibiting unique structures of Sn-rich and Ag-rich compounds. A crystalline star-shaped structure of Sn–Ni–Cu–P was also observed in a solder joint. The intermetallic thicknesses were less than 3μm. The intermetallics growth was about 10% after 3000 thermal cycles. However, these compounds did not affect the reliability of the solder joints. Furthermore, findings in this study were compared with those in previous studies, and the comparison proved the validity of this study.
Year
DOI
Venue
2006
10.1016/j.microrel.2005.05.005
Microelectronics Reliability
Keywords
Field
DocType
failure mode,printed circuit board,thermal cycling,crack propagation,microstructures
Composite material,Microstructure,Intermetallic,Electronic packaging,Electronic engineering,Soldering,Temperature cycling,Fracture mechanics,Solder paste,Reflow soldering,Engineering,Forensic engineering
Journal
Volume
Issue
ISSN
46
2
0026-2714
Citations 
PageRank 
References 
5
0.90
4
Authors
3
Name
Order
Citations
PageRank
Periannan Arulvanan150.90
Zhao-Wei Zhong221236.01
Xunqing Shi350.90