High performance low cost metal-filled composites for embedded passive applications [capacitor materials]

It is essential to find new candidate materials for embedded capacitors. This work presents the development of a novel aluminum-filled high dielectric constant composite. Aluminum is well known as a fast self-passivation and low-cost metal. The thin passivation layer forms an insulating boundary outside of the metallic spheres, which has dramatic effects on the electrical, mechanical, and chemical behaviors of the resulting composites. Influences of aluminum particle size and filler loading on the dielectric properties of composites have been studied. Due to the self-passivation nature of fine aluminum spheres, a high loading level of aluminum can be used while the composite materials continue to be insulating. Dielectric property measurement demonstrates that, for composites containing 80 wt% 3.0 m aluminum, a dielectric constant of 109 and a low dissipation factor of about 0.02 (@ 10 kHz) can be achieved. At such loading level, materials still show good processability and good adhesion toward the substrate. The developed aluminum composite is a promising candidate material for embedded capacitor applications.