Definition

Spread glass (also called flat glass or mechanically spread glass) refers to fiberglass reinforcement that has been flattened or spread to reduce the periodicity of the weave pattern. Standard glass weaves have alternating regions of glass bundles and resin-rich gaps, creating periodic Dk variation that can affect high-speed signals. Spread glass technology fills more of the openings, providing more uniform Dk across the material. This improves impedance consistency and reduces fiber weave effect, important for very high-speed digital designs.