Low loss, high adhesion build-up film based on thermosetting blend of epoxy and maleimide resin

The development of advanced packaging technology has led to increasingly finner circuits, closer spacing, thinner insulating layers, smaller and denser drilling holes in printed electronic circuits. Traditional insulation materials, such as build-up dielectric films and electronic packaging substrates, face big challenges with high dielectric constant and dielectric loss, poor thermal stability, and weak adhesion to conductive layers. This study addresses these issues by developing suitable base resin formulations for build-up films through a detailed evaluations of chemical structures, thermal properties, dielectric performance, etc. with a blended system of epoxy resin and maleimide resin. After comprehensive considerations of thermodynamics, dielectric performance, and processabilities, a composite formulation for build-up dielectric films is determined. The developed build-up film with an epoxy resin to maleimide resin ratio of 8:2 exhibits a dielectric loss of 0.0030 and a dielectric constant of 3.146 at 10 GHz, with an adhesion strength to conductive layer 2.19 N/cm, and a DMA T g 190.9 °C. Meanwhile, the build-up film can pass the stringent requirements of processes such as chemical copper plating, copper sinking, and electroplating.