PCB Assembly Files: Prepare Gerber, BOM & CPL

Gerber and drill data define the board

Include all required copper, mask, legend and outline information together with drill data. A fabrication drawing should identify stackup, material, thickness, finish, copper weight and relevant tolerances. Define impedance requirements when applicable. Confirm that exported files correspond to the intended release rather than a previous CAD save.

The BOM defines what is fitted

Use manufacturer names and exact MPNs, quantity per board, reference designators and population status. Mark DNP items clearly. Separate approved alternatives from suggestions awaiting approval. For partial turnkey, add the supply owner and expected availability for each line. Keep distributor references as supplementary information.

The CPL defines placement locations

Provide designator, X, Y, rotation and board side, with units and origin defined. Check that populated references agree with the BOM. Rotation conventions can differ, so include assembly drawings or component orientation notes for ambiguous devices. A structural checker cannot establish that a coordinate is geometrically correct.

Drawings carry assembly intent

Show polarity, connector direction, special handling, mechanical support and details that are not obvious from copper and coordinates. Include programming files, version information, test instructions and acceptance limits. If fixtures or firmware are unavailable at RFQ time, identify the gap so the quote does not imply completed test preparation.

Package one controlled release

Use a release identifier in the filenames or manifest and include the date and engineering contact. Remove obsolete variants from the final package. Compare the BOM and CPL reference sets, and check quantities for each populated designator. Record what changed when replacing files already submitted for quotation or production.