Woven Thickness
Woven glass fabric designed for thin dielectric layers provides the structural foundation for rigid printed circuit boards. In high density interconnect applications, 1027 glass acts as a lightweight reinforcement with a nominal thickness of approximately twenty micrometers. This fabric style uses very fine yarns to achieve a uniform distribution of glass fibers.
The low profile of the weave helps minimize the variation in resin distribution across the substrate.
Impregnation Rate
The interaction between the glass fibers and the resin system during prepreg production determines the electrical performance of the finished laminate. Since 1027 glass has a relatively open weave structure compared to heavier styles, it requires a high resin content to fill the gaps between the yarns. This high resin ratio leads to a lower overall dielectric constant for the cured dielectric layer because epoxy resin possesses a lower permittivity than E-glass.
This characteristic helps board designers who require fast signal propagation and low signal attenuation. Standard testing involves treating the glass fabric with silane coupling agents to ensure a durable chemical bond between the organic resin and the inorganic glass filaments.
Drilling Behavior
Laser drilling during HDI fabrication requires a highly consistent material to prevent defect formation. When a laser encounters 1027 glass, the thin yarns reduce the risk of beam deflection and ensure clean, uniform via holes. Larger glass styles can deflect the laser or leave protruding fibers that cause plating voids or copper pooling.
The thinness of the material also minimizes the risk of conductive anodic filament growth by reducing the path length for copper migration along the glass-resin interface. Laser ablation tests regularly monitor the drilling quality to ensure that the fabric melts cleanly without tearing or delaminating from the resin.
