Statistical Anisotropic Shrinkage Modeling for Multi-Pass Laser Microvia Target Allocation
Anisotropic polynomial shrinkage modeling reclaims fifteen microns of microvia capture margin, preventing costly multi-pass HDI panel breakout scrap.
Glass Style 2116
Material Specification
Reinforcing fabrics in printed circuit board laminates provide the necessary mechanical stability and electrical insulation to the composite structure. Woven glass style 2116 represents a medium-weight fiberglass fabric commonly used as prepreg or core material in multi-layer board fabrication. This fabric sits between thinner signal-routing layers and thicker power planes to maintain board flatness.
Woven Structure
The woven structure consists of yarns running in both the warp and fill directions to create a stable, grid-like pattern. Glass style 2116 uses a thread count that typically places sixty yarns per inch in the warp and fifty-eight yarns per inch in the fill direction. This construction results in an intermediate thickness that measures roughly four mils when unimpregnated with epoxy resin.
In comparison to coarser fabrics, it offers a more uniform distribution of glass fibers, which reduces the local variation in dielectric constant across the board surface. It provides a balanced ratio of resin to glass, which assists in minimizing the occurrence of signal skew in high-speed differential pairs.
Processing Impact
Laser drilling through this fabric requires a calibrated beam intensity to ensure clean microvia walls. Because the glass yarns are denser than the surrounding epoxy resin, uneven ablation can occur if the laser energy is too low. Process engineers adjust the laser parameters to prevent protrusion of glass fibers into the via, which could cause plating voids during the subsequent wet chemistry steps.
This optimization step ensures the reliability of the vertical interconnects.