Destructive Coupon Microsection Preparation and Optical Feature Extraction
Precision destructive microsection preparation and calibrated optical extraction establish compliance for barrel plating, wrap copper, and internal layer interfaces.
Edge Rounding
Preparation Artifact
Curvature or radius appearing on the sharp corners of a microsection specimen occurs during the abrasive grinding and polishing of the mount. While achieving a flat surface is the goal, edge rounding occurs when the softer encapsulation resin wears away faster than the harder copper or laminate material. This variation distorts the visual perception of plating thickness near the edges of a feature.
Proper support techniques (such as using harder mounting compounds or adding metal shims) minimize this effect.
Measurement Distortion
Inaccurate thickness readings result from the slope created by uneven material removal at the specimen boundary. When edge rounding is present, the interface between the metal and the resin appears blurred or angled, lacking the sharp definition of a properly prepared surface. This makes it difficult for an operator to determine the exact point from which to measure a plating layer.
Using a high-magnification lens and focusing on the center of the feature rather than the edge helps mitigate some measurement error.
Mechanical Variable
Mechanical pressure and the speed of the polishing wheel influence the severity of the geometric change. Longer polishing times with soft cloths exacerbate edge rounding by allowing the abrasive to dig deeper into the resin. Harder lapping films produce a flatter finish that preserves the integrity of the original feature geometry.