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NanoDAC - A powerful method for nanomechanical analysis of polymeric materials

NanoDAC - Ein wirkungsvolles Verfahren zur nanomechanischen Analyse von polymeren Werkstoffen
: Keller, J.; Vogel, D.; Bauer, M.; Michel, B.

Materials Week 2002. Proceedings. CD-ROM
Frankfurt: Werkstoffwoche-Partnerschaft GbRmbH, 2002
ISBN: 3-88355-314-X
9 pp.
Materials Week <2002, München>
Conference Paper
Fraunhofer IZM, Einrichtung Polymermaterialien und Composite ( PYCO) ()
Kompaktzugversuch; Korrelationsanalyse; Mikroriß; Polymer; Rasterkraftmikroskopie; Schadensanalyse; Spannungsintensitätsfaktor; Verformung

Proceeding progress in miniaturization of electronic packages results in the need for experimental methods on a nano scale. The evaluation of very local strain fields at material interfaces, microcracks and defects is the key for the successful design of such highly integrated structures. Furthermore the development of nano materials requires methods for the determination of strain fields in the area of nano scaled particles and at material interfaces. Following this challenge the authors developed the nanoDAC method (nano Deformation Analysis by Correlation), which allows the determination and evaluation of 2D displacement fields based on Scanning Force Microscopy (SFM) images. In the presented paper the strain field at the crack tip of a Compact Tension (CT) specimen was chosen to emphasize the capability of the nanoDAC method. The procedure of extracting information on the displacement field of such a geometric singularity can be divided in three steps. First topographic SFM scans are carried out around the crack tip of the CT specimen in unloaded state. Then the specimen is subjected to increasing mode I loading and images are taken at different load states. In the third and last step the captured images are compared utilizing the wDAC analysis tool which extracts 2D displacement vectors by means of the grey scale correlation technique. With the calculated displacement fields the crack opening displacement can be taken as a measure for the stress intensity factor of the material. NanoDAC was developed and tested at thermoset polymers based on cyanate ester resins. This class of material typically used in microelectronic applications shows a high modulus of elasticity but poor resistance to fracture. The paper presents an introduction in the nanoDAC measurement technique and emphasizes the application in the area of electronic packaging and nano materials.