FPC Fabrication File Set: What Must Match?

First name the fabricated board and the finished switch

The file-set question applies when the membrane switch incorporates a fabricated flexible printed-circuit board, or FPC. A board fabricator needs the electrical layer images, drill or rout data where applicable, profile and fabrication instructions for that board. If the board uses coverlay, stiffeners or defined bend areas, their openings, shapes and locations also belong in the controlled board-data package or fabrication notes. The converter or OEM separately needs overlay, spacer, adhesive, tactile, lighting, tail-end and mounting information for the finished membrane-switch assembly. A correct board package does not resolve those other interfaces.

Do not send a printed-silver PET circuit through a generic copper-board checklist by default. Its artwork and manufacturing controls can be different. Name the actual circuit technology on the RFQ, then let the responsible designer and supplier define the right outputs. Our separate guide discusses how flexible-board design and qualification documents have different roles; this article instead asks whether the specific files delivered to fabrication form one coherent release.

Freeze a manifest before comparing pictures

Record one governing board drawing and source-project revision, the export date, every delivered filename, its intended layer or drill function and the issuer. A ZIP name alone does not establish that its contents were produced from one source revision. Ucamco's X2 attributes can identify layer function; its specification also defines a ProjectId attribute that can carry project and revision information when the exporter supplies it. A buyer still needs a human-readable manifest and drawing control, because optional metadata may be absent and the package may contain non-Gerber documents.

If a drill file is regenerated after the copper layers, make the revision relationship explicit. If the designer intended an exception, have that designer identify the replaced file and issue a fresh, controlled package or approved deviation. The fabricator should not select between conflicting outputs by file modification time or assume the newest-looking drawing governs every layer.

A Gerber Job file can transmit board fabrication details such as finish, overall thickness and materials in machine-readable form; it complements rather than erases the need to check images, drill data and the released drawing. Compare every repeated value in the job file, notes and quotation. Ask the fabricator which fields it actually reads and which project choices need a separate specification.

Reconcile origin, view and numeric format across outputs

For a Gerber fabrication data set, Ucamco revision 2026.05 says its files must align at the same offset, with no mirroring, viewed from the top and at 1:1 scale. That is a file-set rule, not a measured tolerance for a finished flex. Check top and bottom layer roles and the board profile against the source drawing before reviewing a drill overlay.

The NC drill handoff needs its own settings check. KiCad 9 documents separate options for plot origin and drill origin, plus drill units and zero formatting for Excellon output. Altium's fabrication-data guidance says Gerber and NC drill output should use matching origin references and compatible format or precision. The design owner and fabricator should agree which data representation is accepted, then export and inspect the actual generated files; do not infer coordinate agreement from a setup screenshot.

If plated and nonplated holes, slots or routed openings are present, identify their file roles and inspect them against the outline and relevant copper. A local CAM viewer can expose a shifted or mirrored overlay. It cannot prove every net, material property or fabrication rule, so retain design checks and fabricator preflight as separate gates. Keep confidential customer outputs inside an approved local or contracted review environment; this article does not recommend uploading them to a public online viewer.

Inspect the generated set, not only the CAD settings

Open the exact delivery package in an approved local CAM viewer or the fabricator's controlled preflight. KiCad GerbView, for example, can display Gerber and Excellon drill files together, show X2 attributes and compare layers. Confirm the outline closes as intended, the holes register with their copper and profile, the named layer functions are plausible and no unexpected mirrored or offset file appears. Capture the package revision, viewer or preflight method, discrepancy and disposition; a pass is meaningful only for that exact package.

Do not call this visual overlay a completed electrical test, board-build approval or switch qualification. Return unresolved issues to the design owner and actual fabricator. If the board file set changes, rebuild the evidence for the changed package rather than pasting an old screenshot onto a new revision. Separately validate any tail-mating and assembled-panel outcome in its real enclosure and connector context.

Worked example: one new hole file among older layers

Illustrative editorial exercise only—not an HYR customer file, detected defect, CAM result, supplier quote or acceptance record. Imagine a small FPC keypad whose copper and profile plots are issued as board revision C. The designer moves a mounting hole and exports a new drill file after that change, but the ZIP still contains the earlier copper and profile files. Every individual file opens; their common-release identity is now unclear.

The checker records the source-project revision for each file, overlays the delivered copper, profile and drill output, and asks the design owner whether the moved hole requires a board revision D package. It also compares any Gerber Job or fabrication notes to the new drawing. A visible offset would be a hold point; even if the overlay happens to look aligned, the mismatched revision record still needs a controlled explanation. No universal dimensional tolerance or sample count is implied.

Next, the membrane-switch assembler checks whether the hole also locates an overlay, spacer, adhesive opening or housing boss. If it does, a corrected board package alone is insufficient: those assembly drawings and the mounted-sample plan must be reconciled too. The worksheet below routes each question to its proper owner; it does not represent a completed production review.

Challenge five file-handoff failure modes

These are conditional review prompts, not reported HYR field failures. The responsible design and fabrication teams decide whether any one applies to the real construction.

• Mixed revisions: layer files and the drill output come from different source releases. Require a file manifest, regenerated package or explicitly approved exception.
• Different origin or zero format: the drill map shifts when compared with copper/profile. Match the agreed export settings and inspect the actual generated coordinates.
• Wrong view or file role: a bottom layer is mirrored or a mechanical drawing is interpreted as the board profile. Compare the top-view convention, X2 layer function where present and the controlled board drawing.
• Conflicting fabrication notes: a drawing and Gerber Job identify different thickness or material choices. Hold the quote until the design owner defines one governing board construction.
• Board-only approval leakage: the FPC file set passes preflight but the tail, overlay or housing revision changes. Reopen the affected assembled-switch checks instead of transferring the board result to a different stack.

Release the board package and switch assembly as two evidence objects

For the fabricated FPC, request a controlled data package, fabricator-format agreement, preflight observations, open-question log and board acceptance plan. For the finished membrane switch, request the layer section, overlay and spacer geometry, tail-end definition, mounting interface and representative assembled-sample checks. Link both packages by explicit revisions, but do not merge their acceptance records. A board image can be right while the final actuator, connector or enclosure condition remains unresolved.

In the secure HYR RFQ, send the drawings, output manifest and unresolved decisions rather than a statement that the panel is already qualified. The actual quoting team can then identify assumptions and propose project-specific evidence. This guide makes no HYR fabrication, process-capability, yield, tolerance, certification, schedule or customer-result claim, and no named engineer has signed off on the hypothetical example.