What Files Do You Need to Send a PCB for Fabrication?

Detailed Explanation

A complete fabrication package needs to describe the board fully enough that a fab house with no other context can build exactly what was designed. At minimum that means: Gerber files (one per copper layer, solder mask layer, and silkscreen layer), an NC drill file (hole positions and sizes), and a document specifying the stack-up — layer order, copper weight, and dielectric — since Gerber files alone don't inherently convey how layers stack vertically.

For assembly, two more files matter: a pick-and-place (centroid) file giving each component's position, rotation, and reference designator, and a bill of materials (BOM) listing every part, its footprint, and ideally a manufacturer part number. Without both, an assembly house has the bare board and a schematic but no machine-readable instructions for where each component actually goes.

For KiCad users, the complete export workflow — Gerber plot layer selection, drill file generation, coordinate origin alignment, and pre-submission verification in GerbView — is covered in How to Export Gerber Files from KiCad for PCB Fabrication.

Practical Examples

A two-layer board with simple through-hole and SMT parts can typically ship with just Gerbers, a drill file, and a basic stack-up note (it's usually obvious from "2 layers, standard 1.6 mm FR4") — the fab house has little ambiguity to resolve.

A four-layer board with controlled-impedance traces needs its stack-up specified explicitly and unambiguously, because the fab house's actual dielectric thickness and copper weight directly determine whether the delivered board meets the impedance target the design assumed — a vague or missing stack-up drawing here isn't just an inconvenience, it can silently change the board's electrical behaviour.

Design Considerations

• Always include an explicit stack-up drawing for anything beyond a basic two-layer board — don't rely on the fab house guessing layer order or copper weight correctly.
• Generate the BOM and pick-and-place file directly from the same design database as the Gerbers, not a hand-maintained spreadsheet — manual BOMs drift out of sync with the actual layout far more often than generated ones.
• Confirm units and format conventions with your specific fab house before sending files — Gerber format variants and unit conventions (metric vs imperial) have historically been a source of silent misinterpretation.
• Run a final design rule check immediately before generating output files, not before some unrelated later change — output should always reflect the layout's final, DRC-clean state.
• End-to-end fabrication support: If you're navigating a first board submission or a new fab house relationship, a rapid prototyping partner can manage the output package, submission, and first-article review on your behalf.

Common Mistakes

• Sending Gerber files without a stack-up drawing and assuming the fab house will infer the correct layer order and copper weight.
• Maintaining the BOM by hand in a separate spreadsheet instead of generating it from the design database, leading to mismatches between what's documented and what's actually on the board.
• Generating output files before the final DRC pass, then having to regenerate everything after a late layout fix.
• Assuming every fab house interprets Gerber conventions (units, layer naming, aperture format) identically — confirming this in advance avoids a misfabricated first article.