Alumina is widely used in the electronics industry for passive components such as interconnection, resistances, and capacitors and is specifically employed in applications such as substrates for hybrid circuits, multi-layer interconnection circuits, materials for type II condensers, and hyper frequency resonators (mobile phones). The dielectric and excellent thermal shock properties of alumina make it an excellent choice as an insulating material. For applications in very high frequencies (UHF), high purity dense alumina, fired at temperatures above 1600°C, is generally used.