The aim of this work is the comprehensive evaluation of the toughness behaviour of epoxy resin with miniature compact tension specimens. Therefore, the influence of chemical parameters and test conditions (test-temperature crosshead speed) on the crack resistance behaviour and fracture mechanics parameters was examined. The investigation of the fracture behaviour of miniature specimens is based on the crack resistance analysis of standard specimens under quasi-static loading conditions. Furthermore, the practical application of fracture mechanics parameters to structural-integrity assessments is strongly restricted by their limited transferability from specimens to components or devices. Therefore, an extensive investigation was conducted to check out the technical limits of miniaturising the geometry, the validity of specimens size criteria, and the thickness independence of the fracture mechanics parameters. The load-line displacement was measured with the help of a solid-state laser scanner system (Fiedler Optoelectronic GmbH, Lützen). This laser double scanner is favoured for experimental fracture mechanics examinations and works in the transmission mode with two parallel laser beams. The toughness improvement of polymers can be achieved by an enhancement of the energy dissipation capability. The epoxy resin was modified with different kinds of modifiers/flexibilisers.The addition of anorganic particles with a high modulus is a further possibility for modifying the fracture toughness. Both these micro particles in epoxy formulations can improve absorption of energy clearly and therefore improve the toughness as well as the mechanical behaviour and reduce the cost of whole material composition. On the basis of theoretical models, it was intended to provide equations for the evaluation of fracture toughness behaviour. The effect of moisture absorption on the performance of epoxy formulation was studied on an specimens from the field of microelectronics. In Conclusion combination of different kinds of material parameters was used to form a ranking-list for the selection of an epoxy formulation which is resistant to "popcorn".