Creep behavior under cyclic loading

Figure 3-38. An example of strain behavior under various intermittent and cyclic loads, a) Recovery after creep b) a strain increment caused by a stress step function c) strain with stress applied 1) continuously and 2) intermittently.

In actual applications, solder interconnects are often under complex loading conditions (Ref 25). For example, ball grid array (EGA) solder joints may be simultaneously under cyclic shear loading and static tensile (or compressive) loading often with vibration. The deformation behavior and reliability prediction under complex loading conditions warrant further examination. Time and path-dependent creep models are needed for the solder joints under different and often complex loading conditions (Ref 2). 

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