Simulation on the Interfacial Singular Stress-strain Induced Cracking of Microelectronic Chip Under pPower On-off Cycles

Abstract

Thermal fatigue failure of a microelectronic chip usually initiates from the interface between the solder joint and substrate due to the mismatch in coefficients of thermal expansion (CTE). Because of the viscoelastic creep properties of the solders, the stress and strain at the solder/substrate interfaces are strongly dependent on temperature and time. Based on the established creep constitutive models of the solder materials, a three-dimensional thermomechanical analysis of the microelectronic chip undergoing power on-off cycles is conducted based on the finite element method (FEM). The singular interfacial stress-strain fields are obtained and the singular field parameters are quantitatively evaluated. Furthermore, the crack nucleation in power on-off fatigue test of the microelectronic chip is observed, to verify the conclusion that the singular stress-strain induces thermal fatigue failure from the solder/ substrate interface.

Numerical analysis and thermal fatigue life prediction of solder layer in a SiC-IGBT power module

“…Once the accumulative creep strain exceed the critical strain, the element fails and the micro crack nucleates from the corner at the solder-chip or solder-substrate interface. The facts also proved that the thermal fatigue failure generally initiates from the corner of solder layer connected with the chip or substrate [9,10]. Fig.…”

“…It is proved that the most common failure mode in SiC-IGBT power modules, which was encapsulated by more than two SiC-IGBT semiconductor chips in the same substrate according to a certain circuit [8], is main caused by the interfacial cracking from the junction between solder and chip when undergoing alternating thermal loads or called thermal fatigue failure [9][10]. Therefore, it is significant to research the reliability of solder layer under the thermal cycles.…”