Study on epoxy/BaTiO3 composite embedded capacitor films (ECFs) for organic substrate applications

Embedded capacitor films (ECFs) were newly designed for high dielectric constant and low capacitance tolerance (less than ±5%) embedded capacitor fabrication for organic substrates. ECFs are transferable and B-stage films which can be coated on a releasing film. In terms of materials formulation, ECFs are composed of high dielectric constant BaTiO3 (BT) powder, specially formulated epoxy resin, and latent curing agent. And in terms of coating process, a roll coating method is used for obtaining film thickness uniformity in a large area. Differential scanning calorimeter (DSC) thermal analysis was conducted to determine the optimum amount of curing agent, curing temperature, and curing time. Changes in the dielectric constant of epoxy/BaTiO3 composite ECFs with BT particle sizes and contents were investigated. Dielectric constant of 90 was obtained using two different size BaTiO3 powders mixture. Typically, capacitors of 12 μm thick film with 8 nF/cm2 with less than ±5% capacitance tolerance and low leakage current (less than 10−7 A/cm2 at 10 V) were successfully demonstrated on PCBs using epoxy/BaTiO3 composite embedded capacitor films.