In the microelectronics industry, the drive for increasing device speed, level of functionality and shrinking size has placed significant demands on the performance characteristics of polymer dielectrics. In this study, a negative acting, photodefinable dielectric formulation based on a copolymer of decylnorborne (decylNB) and epoxynorbornene (AGENB) was investigated for use in electronics packaging. The structure-property relations of this copolymer were investigated. Copolymer composition and processing conditions were shown to significantly affect the properties of the final polymer films. A lower content of AGENB results in lower moisture absorption, dielectric constant, modulus and residual stress, but it compromises multilayer capability. High crosslink density lowers the dielectric constant but increases the modulus and residual stress. (C) 2004 Wiley Periodicals, Inc.