Definition

A core is a pre-cured laminate sheet with copper foil bonded to both sides - the rigid structural element of a PCB. Cores are manufactured with precise thickness and Dk for impedance control. In multilayer construction, cores are stacked with prepreg (uncured adhesive) between them and laminated under heat and pressure. Core thickness affects impedance, total board thickness, and rigidity. Standard cores range from 0.1mm to 1.6mm. Thinner cores enable tighter impedance control but cost more and are harder to handle. The core's Dk and Df determine electrical performance.