Read the centre comparison literally
The alignment check extracts circular drill hits and source dark copper flashes from successfully rendered layers. For each drill centre it finds the nearest copper flash centre in millimetres and compares their separation with your tolerance. At the default 0.1 mm tolerance, a 0.04 mm separation is within tolerance and a 0.15 mm separation is outside it.
This is a centre comparison, not a test of the final copper shape. A pad can be cleared by later negative artwork, drawn as a region instead of a flash, or belong to a different intended layer. A matching centre therefore does not prove copper containment, plating, connectivity or an adequate annular ring. The report retains the distance so the finding can be interpreted alongside the design.
Treat missing matches as questions
A mechanical mounting hole may deliberately have no copper pad. A large exposed area may contain a hole without a flash at its centre. Conversely, overlapping flash centres on several layers can produce a near-zero distance even if one required layer is absent. Use the inventory and individual layer toggles to understand these cases; a single count is not a manufacturing pass rate.
If no copper flash centres were identified, the comparison is unavailable. The interface does not convert that absence into successful alignment. The visible table shows the first 200 drill hits to keep the page manageable; the downloadable JSON and HTML retain the complete bounded evidence. The tool accepts up to 20,000 copper flashes and 20,000 circular drill hits.
Understand the outline boundary test
When exactly one outline is identified, or you choose its exact filename, the tool compares drill centres with that artwork’s axis-aligned bounding box. The box includes stroke width. A centre inside the box can still be outside a concave board, inside a cutout or beyond a routed edge. Hole diameter and edge clearance are not tested.
An outside-bounds centre is a useful prompt to inspect origin, scale, export revision or a possible outlying feature. It is not automatically a defect. Retain the SVG and report with the original package, then resolve the question using the source board design and the fabricator’s requirements. No combination of these limited findings constitutes DFM, electrical verification or manufacturing certification.