Intermetallic morphology and damage evolution under thermomechanical fatigue of lead (Pb)-free solder interconnections

Multiscale Simulation of Microstructural Changes in Solder Interconnections During Thermal Cycling

“…4 However, observations of failed solder interconnections indicate that the microstructures of solders are not stable and may change significantly during the operation of products. [4][5][6][7] During thermal cycling tests, as-solidified microstructures can transform locally into more or less equi-axed grain structures by recrystallization. The recrystallized region contains a continuous network of grain boundaries, which provide favorable sites for cracks to nucleate and propagate, with less energy consumption than in the as-solidified microstructures.…”

“…[4][5][6][7] The as-solidified microstructures of Sn-rich solder interconnections are usually composed of relatively few large tin colonies distinguished by high-angle boundaries. 4 However, observations of failed solder interconnections indicate that the microstructures of solders are not stable and may change significantly during the operation of products.…”

The Failure Mechanism of Recrystallization‐Assisted Cracking of Solder Interconnections

“…Because recovery and recrystallization are competing processes, the progress of recovery can reduce the driving force of recrystallization significantly and recrystallization may not always initiate. On the other hand, it is well documented that neareutectic SnAgCu interconnections do recrystallize under dynamic loading caused by changes in temperature (between -45 ºC and +125 ºC), as well as under power cycling conditions (between room temperature and +125 ºC) [15,17,18,[56][57][58][59][60][61][62][63]73]. Thus, it seems that near-eutectic SnAgCu solder interconnections recrystallize only under restricted loading conditions: dynamic loading conditions where the strain hardening is more effective than the recovery.…”

“…Therefore, when stress is applied to interconnections having this kind of microstructure, they undergo microstructural evolution before fractures can propagate. Investigations of the microstructures of failed solder interconnections have indicated that the microstructures formed during solidification are not stable and will change notably during the operation of products [15,17,18,[56][57][58][59][60][61][62][63].…”

Simulation of Dynamic Recrystallization in Solder Interconnections During Thermal Cycling

“…However, microstructural changes in the bulk solder have not yet been included in any of the popular prediction models. Especially the microstructural changes associated with recrystallization and grain growth are of importance because they can significantly affect the mechanical properties and can cause recrystallization induced failure of solder interconnections [21][22][23][24][25][26]. A new approach for lifetime prediction needs to be developed that takes into account the microstructural changes.…”