Fabric Structure
Woven fiberglass reinforcement utilized in thin printed circuit board laminates provides dimensional stability and controlled dielectric properties. Industrial specifications designate 1080 spread glass as a lightweight fabric with yarn that undergoes a mechanical spreading process to flatten the bundles. This configuration minimizes the presence of open gaps between the warp and fill fibers.
The action distributes the glass filaments evenly across the sheet, which yields a uniform dielectric constant for signal propagation. It restricts resin-rich zones to small, discrete pockets, preventing localized thermal expansion mismatches that lead to delamination during assembly reflow.
Electrical Performance
Propagation speed variations across differential signal pairs decrease when the reinforcing substrate has a uniform physical profile. High-speed digital circuits suffer from timing skew when one line of a differential pair sits over a glass bundle while the other runs over a resin-rich pocket. Spreading the fibers in 1080 spread glass reduces these localized variations in dielectric constant, keeping the propagation delay matched between parallel conductors.
Laser Processing
Microvia formation by carbon dioxide lasers requires uniform material density to achieve consistent hole diameters. The flat profile of 1080 spread glass provides a uniform barrier to the laser beam. This uniformity ensures that microvias maintain cylindrical shapes.
