Thermal and mechanical characterization of ViaLuX (TM) 81: A novel epoxy photo-dielectric dry film (PDDF) for microvia applications

Multilayered high density interconnect (HDI) processing on organic substrat es typically introduces warpage and residual stresses. The magnitude of the warpage and the residual stresses depends on, among other factors, the pro cessing temperatures and the thermomechanical properties of the dielectric and substrate materials. In this work, a prospective epoxy-based dielectric material for such sequentially built up (SBU) high density-interconnect pr inted wiring boards (HDI-PWB) is considered. The polymer is a photo-dielect ric dry film (PDDF) material called ViaLux(TM) 81, which exhibits a complic ated curing behavior due to the long lifetime of the cationic photoinitiato rs generated by ultraviolet (UV) exposure. The objectives of this work are 1) to conduct differential scanning calorimetry (DSC) experiments and devel op a cure kinetics model; 2) to develop a cure shrinkage model based on thermal and chemical shrinkag e experiments; 3) to determine the thermomechanical properties of partially and fully cure d Vialux(TM) 81 dry film. All of these experimental characterizations are necessary to select suitabl e process parameters and to obtain a consistent product with the desired ph ysical and mechanical properties.