Formation and characterization of Epoxy/$BaTiO_3$ composite embedded capacitor film for PWB application

Abstract

Embedded capacitor technology is one of the effective packaging technologies for miniaturization and high performance of electronic package system. High dielectric constant ceramic-epoxy composites have been of great interest as embedded capacitor material candidates, because they have good process compatibility with multilayer organic susbstrates applications such as pritned wiring boards (PWB). In this work, epoxy/$BaTiO_3$ composite capacitors made of newly developed embedded capacitor films composed of low temperature rapid curing epoxy resin, latent curing agent, and Barium titanate powder were successfully fabricated, and their capacitor properties were characterized. Compared to Epoxy/$BaTiO_3$ composite capacitor paste deposited by a spin coating method, the embedded capacitor films have advantages such as no waste of materials, good film formation capability and processability, long shelf life at room temperature, uniform electrical properties over a large area, and good thermo-mechanical stability after final cure. Crystal structure and tetragonality of two $BaTiO_3$ particles of different size were investigated to understand the effects of particle size on dielectric constant and leakage current. Dielectric constant of the capacitor film made of coarser $BaTiO_3$ particles was higher than that of finer ones. This was due to a higher tetragonality of the coarser particles. Leakage current of the capacitor films fabricated with the coarser $BaTiO_3$ was larger than that fabricated with finer ones. Both the optimum and the average amount of dispersant (with respect to the amount of particle) were higher for finer particles. The curing by the latent curing agent, DICY, occured at temperature greater than 160℃, and the optimum amount of curing agent was found to be 14wt% with respect to the amount of resin. Hence, a capacitor film with dielectric constant 23 was obtained. The dielectric constant was further increased by (ⅰ) increasing the high dielect...