Drill data review for plated and non-plated features

Drill data should identify the geometry of each hole and the manufacturing meaning of the feature. A hole location and diameter do not, by themselves, explain whether the hole is plated or which layers it spans. A rigid-flex release needs those meanings to remain consistent across the drill files, stackup, and fabrication drawing.

Ucamco’s XNC format specification defines attributes for information including plating, layer span, and hole function. It specifies separate files for plated and non-plated holes. Confirm what your exporter produces and what the receiving CAM workflow reads; a familiar file extension is not a complete data description.

Create a hole-family register

Group holes by their intended function and manufacturing definition. Then identify the file that carries each group. Avoid relying on a filename such as “drill-final” to communicate plating or span. Include the drawing reference that defines the acceptance requirement.

State whether a dimension is finished

A fabrication requirement should explain what is being measured. If the drawing calls for a finished hole dimension, label it accordingly and state its tolerance. Do not silently replace that requirement with an assumed tool size. The supplier should resolve the process needed to achieve the agreed finished feature.

For an illustrative discrepancy, imagine a mechanical drawing labelling a mounting hole as non-plated while an export groups it with plated features. Do not decide from its visual position alone. Record the conflict, obtain a design decision, and correct the affected files before release.

Check alignment in one common coordinate system

Open the released outline and drill outputs together in a suitable viewer. Compare known reference features and confirm units, origin, and orientation. A hole pattern that appears internally correct may still be offset from the board outline. Keep a review image or measurement record identifying the files actually checked.

For a multi-region board, also confirm which region contains the feature. A global layer span must be interpreted alongside the local construction, rather than assumed to apply identically everywhere.

Close the export loop

Distinguish design intent from machine instructions

The release package tells the fabricator what feature the finished board must contain. It should not require the customer to guess the production drill compensation. In the XNC specification, the diameter associated with a tool describes the finished feature. Confirm the meaning of the actual format being exchanged rather than generalizing that convention to every legacy file a supplier might receive.

For an illustrative connector hole, write the required finished diameter and tolerance on the controlled drawing and reconcile it with the export. If the supplier asks whether the listed value is before or after plating, treat that question as an unresolved definition, not a minor administrative delay. The answer can affect component fit and must be consistent across the files used for production.

Review a dimensional discrepancy with arithmetic

Suppose an invented mounting requirement specifies a finished non-plated hole of 3.00 mm with a tolerance of ±0.10 mm. Its stated acceptable diameter interval is 2.90–3.10 mm. A drill export showing 3.20 mm conflicts with that requirement even if the displayed hole looks close to the expected size on a zoomed-out board image. The review should identify the discrepancy and obtain the intended design value before release.

Do not resolve that conflict by averaging the numbers or selecting the newest-looking filename. Check the approved mechanical requirement, the native design feature, and the export settings. Correct the source of the disagreement and regenerate the affected outputs. This keeps the released data reproducible; manually patching an export without correcting the design can allow the same error to return on the next revision.

Treat slots as defined shapes

A slot needs an unambiguous width, overall length, end shape, orientation, location, and plating requirement. Be explicit about whether a length dimension describes the complete opening or only the distance between the centers of its rounded ends. These are different dimensions, and a short text note such as “two millimetre slot” does not establish which one is intended.

For a fictional straight slot with semicircular ends, assume an overall length of 4.00 mm and a width of 1.00 mm. The distance between the centers of the two semicircular ends is 4.00 − 1.00 = 3.00 mm. This geometry example helps a reviewer reconcile a centerline representation with the finished outline. It is not a routing instruction or a statement about the tooling a manufacturer will choose.

Inspect the slot in the actual released viewer output, especially when the design system can represent it in more than one way. Confirm that the supplier receives the intended opening rather than an ambiguous combination of overlapping holes and an outline. If an alternative representation is requested, regenerate and review the package using the agreed format instead of attaching a second conflicting definition.

Check the coordinate system using asymmetric references

A symmetric hole pattern can look plausible even when it has been mirrored or rotated. Choose reference features that distinguish the intended orientation, such as an offset mounting hole and a noncentral slot. Compare their positions against the board outline and drawing datums. This makes the alignment check more discriminating than confirming that four corner holes appear somewhere near four corners.

Record the units and at least one known dimension during the review. If a displayed spacing is clearly inconsistent with the mechanical drawing, inspect the import interpretation before moving the pattern by hand. A corrected viewer setup can solve an interpretation issue, whereas manually translating the data may hide a defective export. The accepted package should load in the agreed workflow without an undocumented adjustment.

Reconcile layer spans with local construction

For a limited-span feature, identify its start and end layers in the same naming system as the stackup. Then locate the feature in the regional board map. A globally named layer may not be present in every flexible region, so the review needs both pieces of information. Do not assume that a valid layer pair in one rigid island establishes a valid feature everywhere on the board.

Ask the fabricator to review the proposed feature with the complete construction when the process is still being defined. A hole-family register is a communication tool, not manufacturing approval by itself. The accepted drilling and interconnection approach should be tied to the reviewed stack revision so a later regional change cannot silently invalidate the original process discussion.

Assign each question to an owner

Some discrepancies require a mechanical design decision, such as which finished hole fits a locating pin. Others require an electrical decision, such as whether a feature is intended to connect copper layers. Manufacturing can explain feasibility and process implications, but it should not have to invent missing product intent. Record who is responsible for each answer and place the resolved definition in the controlled package.

When a supplier sends a proposed change, identify whether it alters the finished requirement or only the manufacturing method used to achieve it. The distinction determines which owner needs to approve the change. Keep the accepted response with the revision record instead of relying on an isolated message that a later production team may not receive.

Review the complete output set after a correction

After fixing a feature, recheck the files that could be affected by the regeneration. The drill file, drawing table, slot output, and stack reference should still describe the same revision. A correct replacement file placed beside an obsolete file with a similar name creates a new interpretation problem. Use a release manifest that identifies the active files and their roles.

Finally, preserve the review evidence with the package. A useful record names the exact files inspected, the known dimensions checked, the discrepancies found, and the decisions that closed them. It need not contain screenshots of every hole. It should demonstrate a deliberate check of geometry and manufacturing meaning, so the next reviewer can understand what was accepted and reproduce the handoff.

• Match each hole family to a controlled drawing requirement.
• Confirm plating and span are communicated in the agreed data format.
• Inspect the exported files, not only the native design.
• Resolve conflicts before issuing the manufacturing package.
• Retain the accepted output set with its revision and approval record.

For repeat orders, compare the requested revision with the previously accepted package before reusing its approval. An unchanged part name does not establish unchanged drill data. A short revision comparison can identify whether the earlier review still applies or whether a specific hole family needs renewed attention.

Read our manufacturing handoff overview and design guide. Send your drill data and fabrication drawing with any plating or layer-span questions highlighted.