Woven Geometry
Fiberglass reinforcement of the 1078 glass fabric style designates a thin-gauge woven substrate used to support resin in high-speed, multi-layer printed circuit boards. Fabricated with a nominal thickness of approximately 0.043 millimeters, 1078 glass fabric features a relatively open weave that allows resin to flow through the yarn gaps during lamination.
Resin Absorption
Capillary action during prepreg manufacturing draws resin into the bundled filaments. Since the style consists of fine yarns woven with fifty-four ends per inch in both directions, the material provides a balanced mechanical strength. It acts as a stable carrier for epoxy resins, yielding a predictable dielectric thickness once pressed.
Laminators use it to achieve precise impedance values in high-speed signal pathways.
Dielectric Influence
Spatial variation in the glass-to-resin ratio across the woven pattern affects signal propagation velocity. Signals traveling over the dense glass yarn experience a different dielectric constant than those traveling over resin-rich gaps. Using dual plies of 1078 glass fabric or rotating the trace direction minimizes the resulting skew.
This mechanical layout avoids signal degradation in high-frequency circuits by averaging the localized permittivity differences across the substrate area. Board designers specify this fabric when thin-gauge layers require uniform dielectric performance.
