Volume 06,Issue 04

Comparative Study of Physics of Failure Assessments of Thermomechanical Fatigue for Solder Joints in Multichip Module Under Different Conditions

Authors

Cheng-Geng Huang

Abstract
A multi-chip module (MCM) which is integrated by multiple integrated circuits (IC) into a unified substrate can significantly reduce the interconnection spacing between various chips and enhance the electrical characteristics. Despite multi-chip module’s greater performance compared with traditional encapsulation, the corresponding problem is mainly induced by thermo-mechanical, and the reliability assessment has also been a critical issue in the electronic industry. The creep-fatigue failure of solder joints under cyclic temperature fluctuations, which is caused by both ambient temperature changes and internal power cycling, plays an important role in the thermo-mechanical reliability of the MCM. In order to assess the influence of cyclic temperature loading profiles on the fatigue life of the solder joints, three different kinds of temperature-related qualification tests, i.e. accelerated temperature cycles (ATC), thermal shock cycles and modified temperature cycles with 10-minutes dwell period, are utilized in the finite element analysis (FEA). Using the FEA method, we can obtain the critical solder joints located in the outer corner of the substrate in MCM and the specific failure location of the solder joint, which is validated by the optical micrograph. Furthermore, based on the energy-partitioning damage model, a comparative analysis of the fatigue life of critical solder joints under various temperature loading profiles is made. The results obtained can improve the design and manufacture in the field of microelectronics encapsulation. For a basic qualification test, these results can also provide the guidelines for the engineers and manufacturers.

Keyword: Thermo-mechanical reliability, Creep-fatigue failure, Qualification tests, Solder joints, Multi-chip module.

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