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  • Author: G. Gergely x
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Open access

D. Koncz-Horváth, G. Gergely and Z. Gácsi

Abstract

In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.

Open access

G. Gergely, D. Koncz-Horváth, Z. Weltsch and Z. Gácsi

Abstract

This work represents an interesting development in the detection and interpretation of crack evolution in through hole technology (THT) solder joints, which based on the development of general and common method. Serial sectioning is a useful method because it overcomes the problems associated with traditional two-dimensional metallographic techniques by providing information about (micro)structures in three-dimensions.

In our work, serials sectioning with reconstruction method was utilized to visualize the 3D nature of cracks in through hole solder joint. Accurate quantitive analysis of the cracks, such as crack length, position and extension are presented with a help of the developed method: newly defined parameter and serial-cross sectioning method.

Open access

D. Koncz-Horváth, G. Gergely and Z. Gácsi

Abstract

In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.

Open access

A. Simon, D. Lipusz, P. Baumli, P. Balint, G. Kaptay, G. Gergely, A. Sfikas, A. Lekatou, A. Karantzalis and Z. Gacsi

Abstract

The scope of the research work is the production and characterization of Al matrix composites reinforced with WC ceramic nanoparticles. The synthesis process was powder metallurgy. The produced composites were examined as far as their microstructure and mechanical properties (resistance to wear, micro/macrohardness). Intermetallic phases (Al12W and Al2Cu) were identified in the microstrucutre. Al4C3 was not detected in the composites. Adding more than 5 wt% WC to the aluminum, microhardness and wear resistance exceed the values of Al alloy. Composites having weak interface bond performed the highest wear rate.