Local Measurements of Strain using Laser Speckle Techniques
Sprache des Titels:
Tagung Microcar 2005
Non-contacting strain measurements of micromaterials are expanding fields in materials science for various applications. Optically based methods without needs of surface-marking or -preparation therefore are of major advantage and open new testing potentials, when standard testing techniques cannot be used.
Properties for materials as applied in microelectronics and microsystems can differ significantly from those determined on bulk materials when the dimensions of the specimen become very small (“size effect”). In addition, these differences can also be caused by changes in topology as in thin polymer layers, by the impact of manufacturing or by component specific aging. Consequently, to increase the reliability of components in microelectronics and micromechanics, it is frequently required to determine mechanical and thermal properties of the base material in its practical dimensions and the properties have to be measured directly on the components.
We present a new laser speckle based strain sensor, which gives local strain information of surface elements in the range of 1 mm, especially suitable for measurements of thermal and mechanical strain on thin structures (like free-standing films, foils, fibres, fibre bundels and bonding wires with typical dimensions of a few microns in thickness). A wide range of materials can be investigated, like metals, polymers, glasses, ceramics and multilayer-structures. The system can also be applied to bulk materials with various, non-standardized geometries.