Low-Cycle Fatigue Behavior of 95.8Sn-3.5Ag-0.7Cu Solder Joints

• Published in: Journal of electronic materials Vol. 42; no. 1; pp. 192 - 200
• Main Authors: Tang, Y., Li, G.Y., Shi, X.Q.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 2013; Springer; Springer Nature B.V
• Subjects: Applied sciences; Brazing. Soldering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electronics; Electronics and Microelectronics; Exact sciences and technology; Fatigue life; Fractures; Instrumentation; Joining, thermal cutting: metallurgical aspects; Joints; Materials; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Optical and Electronic Materials; Soldering; Solid State Physics; frequency effect; Low-cycle fatigue; lead-free solder; temperature effect; Coffin–Manson model; Temperature dependence; Scanning electron microscopy; Experimental data; Creep; Cross section; Ductility; Temperature effect; Cross section (collision); Frequency effect; Low cycle fatigue; Temperature coefficient; Lifetime; Stress relaxation; Fatigue test; Soldered joint; Lead free solder; Coffin—Manson model; Fractography; Fracture mode
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-012-2258-4

Low-cycle fatigue (LCF) behavior of 95.8Sn-3.5Ag-0.7Cu solder joints was investigated over a range of test temperatures (25°C, 75°C, and 125°C), frequencies (0.001 Hz, 0.01 Hz, and 0.1 Hz), and strain ranges (0.78%, 1.6%, and 3.1%). Effects of temperature and frequency on the LCF life were studied. Results show that the LCF lifetime decreases with an increase in test temperature or a decrease of test frequency, which is attributed to the longer exposure time to creep and the stress relaxation mechanism during fatigue testing. A modified Coffin–Manson model considering effects of temperature and frequency on the LCF life is proposed. The fatigue exponent and ductility coefficient were found to be influenced by both the temperature and frequency. By fitting the experimental data, the mathematical relations between the fatigue exponent and temperature, and ductility coefficient and temperature, were analyzed. Scanning electron microscopy (SEM) of the cross-sections and fracture surfaces of failed specimens at different temperature and frequency was applied to verify the failure mechanisms.