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Lifetime prediction of thick aluminium wire bonds for mechanical cyclic loads

: Merkle, L.; Sonner, M.; Petzold, M.


Microelectronics reliability 54 (2014), Nr.2, S.417-424
ISSN: 0026-2714
Fraunhofer IWM ( IMWS) ()

This paper develops a lifetime prediction model for thick aluminium wire bonds from purest (99.999%) aluminium in order to determine their lifetimes under a mechanical cyclic load. To this end, wire bonds were mechanically cyclically loaded on a test bench, and the resulting strain was calculated by means of finite element (FE) simulation. This FE simulation allows the experimentally derived lifetime to be described using the calculated damage parameter in a Manson-Coffin approach. The most conclusive damage parameter for the purposes of the simulation is dissipated energy per cycle. Various bonding process parameters were examined to establish their effects on lifespan. The greatest influences were found to be loop height and wire diameter. Increasing the former and reducing the latter influences lifetime positively under mechanical cyclic loading. The effects of load symmetry and the bonding process were determined to have a relatively insignificant influence on lifetime.