D-Coupon Testing

Coupon Geometry

Fabrication panels incorporate standardized geometric arrays alongside actual circuit boards to simulate identical thermal mass and etching dynamics. Plating current distribution varies across large panels, meaning perimeter test coupons receive higher current density than internal cavities. Coupon placement strategies dictate that specific extraction zones match the highest copper density found on the functional printed circuit board.

Laboratory technicians grind through the resin encapsulated coupon until the geometric center of each barrel is visible under polarized light. Dimensional verification depends on strict adherence to established aspect ratios rather than visual appearance alone.

Failure Boundaries

Acceptance thresholds differentiate structural defects from acceptable cosmetic variations within the barrel wall. Minimum copper thickness requirements dictate that barrel walls maintain specified vertical continuity without annular ring separation or internal cracking. Thermal stress exposure through multiple solder float cycles simulates extreme assembly conditions before microscopic evaluation begins.

Rejection occurs immediately when barrel wall fracturing exceeds established dimensional tolerances, halting shipment of the entire production batch. Micro-section analysis cannot predict localized performance failures occurring outside the sampled coupon boundaries.