Trapezoidal Etch Factor

Calculation Methodology

Analysts determine the result by dividing the vertical depth of the etched sidewall by the horizontal width of the undercut on one side of the conductor. High values denote a nearly vertical wall profile, whereas low values indicate significant lateral erosion that rounds or narrows the trace geometry. Engineers use cross-sectional inspection of coupons to verify that these values remain within the tolerances defined by the board design requirements.

Operational Consequence

Consistent etch profiles guarantee reliable performance during the subsequent assembly stage where solder masks and conformal coatings must adhere to uniform copper surfaces. Deviations from expected profiles lead to uneven skin effect losses or mismatched impedance values in fine-pitch circuit designs. Proper management of this physical characteristic improves the predictability of board-level interconnects across production cycles.