Effects of Voids and Their Interactions on SMT Solder Joint Reliability

Several finite element models were proposed to investigate the effects of voids and their interactions on SMT solder joint reliability in thermal mismatch loading. Both linear elastic analysis and non‐linear and time‐dependent finite element analysis were performed on models with different sizes and locations of voids in solder joints. The focus was on the interactions of the two voids. Various distances between voids are considered. Constitutive equations accounting for both plasticity and creep for one solder material were assumed and implemented in a finite element program. The following observations have been obtained: (i) the stress and strain in a solder joint of two voids are different from those of a one void joint; (ii) the stress and strain reach a maximum for a particular void size and location either along the interface of the solder joint or at the edges of voids; (iii) the initiation of interfacial debonding may be induced by the interaction of the voids; (iv) creep due to thermal cycling has a significant effect on solder joint reliability.