In this paper we present our results on how nanoindentation can serve for measurement of (local) mechanical properties in microelectronic materials and components. Special attention is paid to the properties of interface regions, i.e.. the region of intermetallic bonds. Finally a finite element model is presented in order to simulate the full indentation process.

Fabrication of modern microelectronic components requires miscellaneous solder materials for joining. In order to guarantee the quality of the manufacturing process and the reliability of the resulting solder joint it is necessary to know the material properties of the joining parts and of the solder materials. In particular Young's modulus, yield stress, and the hardness are of great interest. Moreover, a complete stress-strain curve is important for a detailed material characterization and simulation of a component, e.g., by Finite Elements (FE). The miniaturization of modern electronic products with small solder joints allows only fabrication of very small-sized specimens. Because of this miniature tests are used for measuring the mechanical properties of the solders in the experimental investigations of this paper. More specifically two miniature tests are presented and discussed, a mini-uniaxial-tension-test and a nanoindenter experiment. In the tensile test the axial loading is prescribed, the corresponding extension of the specimen length is recorded, both of which determines the stress-strain-curve directly. The stress-strain curves are then mathematically analyzed by assuming a non-linear relationship between stress and strain of the Ramberg-Osgood type and fitting the corresponding parameters to the experimental data by means of an optimization routine. For a detailed analysis of very local mechanical properties nanoindentation is used, resulting primarily in load vs. indentation-depth data. According to the procedure of Pharr and Oliver this data can be used to obtain hardness and Young's modulus but not a complete stressstrain curve, at least not directly. In order to obtain such a stress-strain-curve, the nanoindentation experiment is combined with FE and the coefficients involved in the corresponding constitutive equation for stress and strain are obtained by means of the inverse method. Finally in this paper, the stress-strain curves from nanoindentation and tensile tests are compared for two materials, namely aluminum and steel and differences are explained in terms of the locality of the measured properties.

The regulatory compliance of the containment system is of essential importance for the design assessment of transport packages for radioactive materials. The requirements of the IAEA transport regulations SSR-6 for accident conditions implies high load on the containment system of Type B(U) packages. The integrity of the containment system has to be ensured under the mechanical and thermal tests. The containment system of German transport packages for spent nuclear fuel (SNF) and high level waste (HLW) usually includes bolted lids with metal gaskets. BAM Federal Institute for Materials Research and Testing as the German competent authority for the mechanical and thermal design assessment of approved transport packages has developed the guideline BAM-GGR 012 for the analysis of bolted lid and trunnion systems. According to this guideline the finite element (FE) method is recommended for the calculations. FE analyses provide more accurate and detailed information about loading and deformation of such kind of structures. The results allow the strength assessment of the lid and bolts as well as the evaluation of relative displacements between the lid and the cask body in the area of the gasket groove. This paper discusses aspects concerning FE simulation of lid systems for SNF and HLW transport packages. The work is based on the experiences of BAM within safety assessment procedures. The issues considered are the assessment methods used in the BAM-GGR 012 for bolted lid systems along with the nominal stress concept which is applied for bolts according to that guideline. Additionally, modeling strategies, analysis techniques and the interpretation of the results are illustrated by the example of a generalized bolted lid systems under selected accident conditions of transport.

The requirements of the IAEA safety standards for Type B(U) packages include the thermal test as part of test sequences that represents accident conditions of transport. In comparison to mechanical tests, e.g., 9 m drop onto an unyielding target with short impact durations in a range of approximately 10 ms to 30 ms, the extended period of 30 min is defined in regulations for exposure of a package to a fire environment. Obviously, the required containment capability of the package has to be ensured not only after completing the test sequence but also over the course of the fire test scenario. Especially, deformations in the sealing area induced by the non-uniform thermal dilation of the package can affect the capability of the containment system. Consequently, thermo-mechanical analyses are required for the assessment. In this paper some aspects of finite element analysis (FEA) of transport packages with bolted closure systems under thermal loading are discussed. A generic FE model of a cask is applied to investigate the stress histories in the bolts, lid, and cask body as well as the deformations in the sealing area and the compression conditions of the gasket. Based on the parameter variations carried out, some recommendations in regard to modeling technique and results interpretation for such kind of analyses are finally given.

Für die zuverlässige Herstellung und den Gebrauch immer kleiner werdender Geräte und Strukturen ist die Kenntnis der zugehörigen Werkstoffeigenschaften unerlässlich. Deren Ermittlung muss an Miniaturproben durchgeführt werden, da die gebräuchlichen, auf Standardproben beruhenden Verfahren keine verlässlichen Aussagen über das Materialverhalten im µm-Bereich geben. Aus diesem Grund wird hier die Ermittlung lokaler Parameter von Werkstoffen in Bauteilen in Anlehnung an die Untersuchung bleifreier Lotwerkstoffe mit Hilfe der sog. Nanoindentation beschrieben. Das Verfahren dient in erster Linie der Bestimmung von Standardwerkstoffkennwerten wie dem Elastizitätsmodul, der Fließgrenze und der Härte. Des Weiteren ist die Nanoindentation in der Lage, über den Ansatz der inversen Methode ein vollständiges Spannungs-DehnungsDiagramm zu ermitteln, welches in dieser Arbeit mit dem Ergebnis eines herkömmlichen Zugversuchs verglichen wird.