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Modeling the rate-dependent inelastic deformation behavior of porous polycrystalline silver films

: Letz, S.A.; Farooghian, A.; Simon, F.B.; Schletz, A.


Microelectronics reliability 88-90 (2018), S.1113-1117
ISSN: 0026-2714
Fraunhofer IISB ()

During the last years more and more investigations on the viscoplastic behavior of sintered silver inter-connections were published. To classify the meaning of the rate-dependency of porous silver films a good model description is necessary. Since different formulations are available and already used, this work focusses on different continuum mechanics modeling strategies for describing the experimental results. Creep tests at different load and temperature levels as well as monotonic hardening tests were conducted. Two different creep approaches and one viscoplastic approach were used to model the rate-dependency. For all approaches, an instantaneous plastic strain was also considered. The models were parameterized by means of inverse modeling and the Finite-Element-Method. Different load scenarios were computed and the solutions compared. It was found that the hardening experiments were correctly predicted by all models. For multiple-hardening-relaxation computations, large differences between the viscoplastic and the creep models were observed. Two possible reasons could be identified and were discussed. Finally, the results obtained were used to give recommendations for different applications in simulation of electronics packaging issues.