JLCPCB File Checklist — What to Submit and How to Verify

Avoid the First-Order Back-and-Forth

First-time JLCPCB customers spend 1-2 days going back and forth on file issues before the first board ships. Missing layers, wrong drill format, BOM parts not in JLC's library, CPL with wrong column order — these are all preventable with a pre-submission checklist. This guide walks through the exact files JLCPCB needs for bare PCB, SMT assembly, 3D printing, and stencil services, plus a verification workflow that catches issues before submission.

JLCPCB's File Expectations

JLCPCB accepts Gerber RS-274X (preferred), Gerber X2 (also accepted), KiCad .kicad_pcb files (auto-converted), and Altium .PcbDoc with caveats. The Gerber zip should contain one file per layer (top copper, bottom copper, top mask, bottom mask, top silk, bottom silk, paste layers, outline) plus one Excellon drill file. JLC's gerber viewer at jlcpcb.com/quote pre-validates everything — issues flagged here will block fabrication, so always run it before checking out. The full design rule spec is at jlcpcb.com/capabilities.

What This Checklist Covers

• Bare PCB files — Gerber zip, Excellon drill, outline layer, soldermask color options.
• SMT assembly extras — BOM CSV format, CPL/centroid CSV, JLC parts library validation.
• 3D printing files — STL, STEP, when to use which.
• Stencil ordering — paste layer Gerber, stencil thickness selection.
• Design rules — 5/5 mil 2-layer, 4/4 mil 4-layer, drill minima, board size limits.
• Pre-submission verification — three-step workflow with MakerSuite 3D, JLC viewer, BOM tool.

How to Verify Before JLCPCB Submission

1. Open pcbviewer.app and drop your Gerber zip. The 3D rendering shows missing layers immediately.
2. Check the layer panel — every expected layer (Cu, mask, silk, paste, outline) should be present and visible.
3. Open the BOM panel and run LCSC search. Parts marked 'pre-order' will incur surcharges and longer lead times.
4. Upload the same zip to JLCPCB's gerber viewer (jlcpcb.com/quote) for design-rule violation flagging.
5. For SMT, use JLC's BOM tool to validate every part has a JLC code. Mark missing-code parts as 'Pre-Order' or substitute.

Why First-Order Verification Pays Back

JLCPCB's customer support is asynchronous email with 24+ hour response times in either direction. A single missing layer adds 24-48 hours to your turnaround. Multiply that by every back-and-forth on a problematic submission and a 5-day order becomes a 2-week saga. Pre-flighting your files in MakerSuite 3D and the JLC web viewer before checkout costs 10 minutes and saves 1-2 days of email ping-pong. For prototypes where deadline matters, this is the highest-ROI process improvement available.

When the Checklist Saves Time

• First JLCPCB order — every common mistake (missing drill, wrong outline layer, BOM parts) caught upfront
• Switching from another fab — JLC has slightly different conventions vs PCBWay/OSH Park
• Tight deadlines — pre-flight catches the issues that would otherwise eat 1-2 days of lead time
• SMT first-time customer — BOM tool validation finds parts that need substitution before order
• Recurring production — checklist as part of standard release process catches engineering oversights

Browser-Side Parsing, No Upload

PCB files often contain trade-secret product designs. MakerSuite 3D parses files entirely in your browser; no server upload, no cached copy. Layer geometry, component positions, and BOM data all stay on your machine. JLCPCB submission still uploads to their service per your standard order workflow — that's outside MakerSuite 3D's scope.