Compensation Modification
Pre-production modification accounts for the predictable reduction of feature widths during chemical removal of copper. Applying artwork compensation involves increasing the size of pads and tracks on the digital plot to offset the effects of lateral erosion. The adjustment ensures that the final etched copper features match the dimensions required by the circuit design.
Failure to apply this change leads to traces that are too thin, which increases electrical resistance.
Correction Mechanism
Manufacturing etch occurs both vertically and horizontally once the etchant penetrates the copper foil. Because the liquid removes metal from the sides of a trace while moving toward the substrate, the resulting feature is narrower than the original resist pattern. This etch factor varies depending on the weight of the copper foil and the chemistry of the etching bath.
Thicker copper requires a more aggressive artwork compensation to maintain the structural integrity of fine lines. An incorrect calculation results in deviations from the target impedance in high speed signals.
Production Capability
Process boundary for this adjustment is reached when the increased feature size on the artwork reduces the clearance between adjacent conductors below the minimum required for reliable fabrication. High density designs often require thinner copper to minimize the need for extreme artwork compensation.
