Use the limited JLCPCB basic preflight

The JLCPCB basic CSV profile adds a small documented subset of format checks to the factory-neutral comparison. It does not simulate the uploader, submit files, select stock or approve an assembly. Review the current official instructions again before placing an order.

Map the original required fields

The profile expects BOM headers Comment, Designator, Footprint and CPL headers Designator, Mid X, Mid Y, Layer, Rotation. Required cells must be non-empty. This check follows the fields named in JLCPCB's BOM guide and CPL guide.

BOM: Designator,Quantity,Populate,Comment,Footprint
R1,1,yes,10k,0603

CPL: Designator,Mid X,Mid Y,Rotation,Layer
R1,12.4,8.2,0,Top

Quantity and Populate are local checking columns, not a claim that the factory requires them. Map BOM references to Designator, and CPL references, X, Y, rotation and layer to their matching original fields. A file containing both X and Mid X cannot satisfy this profile by mapping X instead. The checker validates the selected column, so a second unused header cannot hide the mistake.

The profile requires millimeters and Top/Bottom layer values. Choosing inches creates a blocker even when every coordinate is a valid number. Change the CAD export or another reviewed copy; the discrepancy export contains issues, not a converted submission file.

Keep reference identity explicit

The preparation recommendations limit a BOM row to 200 designators. The profile checks the expanded per-row count and flags longer rows. Source: JLCPCB preparation recommendations.

The official BOM page describes uppercase normalization, while the preparation page warns about inconsistent capitalization. These statements leave an operational ambiguity. The conservative local rule is to block case mismatches in this profile until the two files agree exactly. Factory-neutral mode reports the same discrepancy as a warning.

Range expansion is a local analysis convenience. It does not prove that the receiving uploader accepts range syntax in the unchanged CSV. Use explicit individual designators in the actual submission unless your factory confirms the syntax.

Understand what remains unchecked

• Whether a footprint, value or manufacturer part number identifies the intended physical part.
• Library stock, sourcing, component matching selections and assembly eligibility.
• Centroid origin, bottom-side mirroring, polarity, pin 1 and footprint rotation offsets.
• Gerber revision, board outline, panelization, clearances and manufacturing tolerances.
• All manufacturer rules beyond the limited fields and bounds listed here.

Official pages were reviewed on October 31, 2026. Changes to the manufacturer's requirements may precede updates to this profile. The source register records the evidence and support boundary. Use the factory preview and human assembly review even when the report has no blockers or warnings.