Band 54, Heft 7

Defects in electronic components and defects caused by electronic components are a frequent cause of fire damage. 35 % of examined cases of fire damage are found to be caused by electrical equipment or by the handling of electricity. Fire damage caused by electronic elements and in electronic assemblies may have a multitude of causes. Minor damages occurring during the manufacture of electronic components and assemblies can lead to operational disruptions in electronic devices and to life-threatening situations. In order to reconstruct a fire damage, a complex failure analysis and comprehensive knowledge of the principle of operation of the devices is required. Metallographic target preparation serves to detect and describe faults. Some damage patterns taken from practice are presented and analyzed here.

In the present work, six specimens of hypo-eutectic Al-3Si-0.45Mg-0.45Cu-0.2Sc-0.2Zr cast alloys were made by a traditional casting process. The changes in microstructure and mechanical properties of the alloys at different Sr concentrations were studied using metallographic observation, tensile strength testing, and SEM analysis. The results show that, when the Sr content increased, the grain morphology underwent significant changes, from dendrites to isometric grains, and the Si phase in the eutectic region was greatly transformed and its grain sizes became smaller. However, over-modification, in excessive Sr content samples affected the mechanical performance overall. The best morphology with regards grain size and the silicon phase appeared in 0.06 % and 0.08 % Sr concentration specimens. The mechanical properties of the alloy were maximised and then decreased with increasing Sr concentration. The tensile test results indicated that the alloy with the best mechanical properties was that at 0.08 % Sr addition as evinced by its optimal morphological parameters.