Silica Filled Resin Viscosity Minimization during High Pressure Lamination Ramps
Silica-filled resin viscosity minimization requires synchronizing heating ramps with press pressure timing to ensure complete void encapsulation without core shift.
Drill to Copper Clearance
Separation Distance
Fabrication rules specify the minimum space required between the edge of a drilled hole and any adjacent non-connected internal copper features. Maintaining sufficient drill to copper clearance ensures that misalignment between layers does not cause unintended short circuits between signal traces and plated barrels. It accounts for the cumulative error found in registration, drill bit wander and material movement during lamination.
Insulation Integrity
Dielectric layers between the barrel and the internal plane must resist the high electrical gradients present in modern densely packed modules. If the spacing is too narrow, the risk of conductive anodic filament growth increases over the service life of the hardware. Mechanical stress from the expansion of the board during thermal cycles can also fracture thin epoxy walls between copper areas.
Designers expand the keep-out regions around non-functional pads to safeguard against these potential long-term field failures.
Precision Requirement
Registration accuracy defines the safe threshold where the manufacturer can place features without risking a breakout. Advanced optical alignment systems allow for tighter clearances by tracking the shifts in individual core layers prior to the final bonding process. A design that ignores these limits will suffer from low yields at the electrical testing station.