the out of plane direction (Z). This differential expansion and contraction will induce cyclic fatigue in the copper plating, eventually resulting in crack propagation and an electrical open circuit. Various design, material, and environmental parameters will influence the rate of this degradation. To ensure via robustness, IPC sponsored a round-robin exercise that developed a time to failure calculator. Vias in integrated circuits In integrated circuit (IC) design, a via is a small opening in an insulating oxide layer that allows a conductive connection between different layers. A via on an integrated circuit that passes completely through a silicon wafer or die is called a through-chip via or through-silicon via (TSV). Through-glass vias (TGV) have been studied by Corning Glass for semiconductor packaging, due to the reduced electrical loss of glass versus silicon packaging. A via connecting the lowest layer of metal to diffusion or poly is typically called a "contact". Gallery See also Through-hole technology (THT) Surface-mount technology (SMT) Through-silicon via (TSV) Via fence Feedthrough Notes References Further reading External links Online Via Calculator (Ampacity, Capacitance, Impedance, Power Dissipation Calculation). Electronic design Electronics manufacturing Printed circuit board manufacturing