Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

• Published in: Journal of alloys and compounds Vol. 578; pp. 110 - 117
• Main Authors: Xiao, H., Li, X.Y., Hu, Y., Guo, F., Shi, Y.W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25.11.2013; Elsevier
• Subjects: Applied sciences; BIMETALS; Brazing. Soldering; Condensed matter: structure, mechanical and thermal properties; Continuum damage mechanics; Copper; Cycles; Damage; Damage behavior; ELASTIC STRAIN; Evolution; Exact sciences and technology; Fatigue, brittleness, fracture, and cracks; Joining, thermal cutting: metallurgical aspects; JOINTS; Law; MATHEMATICAL ANALYSIS; Mathematical models; Mechanical and acoustical properties; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physical properties of thin films, nonelectronic; Physics; SnAgCu/Cu solder joint; SOLDERING ALLOYS; Solders; STRAIN; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermomechanical cycling; THERMOMECHANICAL TREATMENTS; TIN ALLOYS (50 TO 99 SN); Thermomechanical cycling; SnAgCu/Cu solder joint; Continuum damage mechanics; Damage behavior; Scanning electron microscopy; Flip-chip; Thermal cycle; Mechanical properties; Fatigue; Deformation measurement; Experimental result; Soldered joint; Continuum mechanics; Microstructure; Damaging
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.05.026

•A creep–fatigue damage model based on CDM was proposed.•Designed system includes load frame, strain measure device and damage test device.•Damage evolution of solder joints was a function of accumulated inelastic strain.•Damage of solder joints is an interaction between creep and low-cycle fatigue. Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D=1−R0/R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints.