JLCPCB — PCB Fabrication & Assembly
JLCPCB is a PCB fabrication and assembly service based in Shenzhen, China. It is a sister company to LCSC Electronics (common ownership) — they share the same parts library.
Typical usage: Order bare prototype PCBs + framed stencil from JLCPCB during prototyping (parts sourced separately from DigiKey/Mouser, hand-assembled in lab). For production runs (100s qty), order fully assembled boards from JLCPCB using LCSC parts. PCBWay is an alternative assembler. For component searching, see the lcsc skill. For BOM management, gerber/CPL export, and stencil ordering, see the bom skill.
Related Skills
| Skill | Purpose |
|---|---|
kicad | Read/analyze KiCad project files, DFM scoring against JLCPCB capabilities |
bom | BOM management, gerber/CPL export, stencil ordering |
digikey | Search DigiKey (prototype sourcing, primary — also preferred for datasheet downloads via API) |
mouser | Search Mouser (prototype sourcing, secondary) |
lcsc | Search LCSC (production sourcing — JLCPCB uses LCSC parts library) |
pcbway | Alternative PCB fabrication & assembly |
emc | EMC pre-compliance risk analysis — run before fab to catch EMC issues |
spice | SPICE simulation — verify analog subcircuits before committing to fab |
Assembly Parts Library
Part Categories
| Category | Description | Assembly Fee |
|---|---|---|
| Basic | ~698 common parts (resistors, caps, diodes, etc.) pre-loaded on pick-and-place machines | No extra fee |
| Preferred Extended | Frequently used extended parts | No feeder loading fee (Economic assembly) |
| Extended | 300k+ less common parts loaded on demand | $3 per unique extended part |
LCSC Part Numbers
Every assembly component is identified by an LCSC Part Number (Cxxxxx, e.g., C14663). This is the definitive identifier for BOM matching. See the lcsc skill for searching parts.
Parts Search (JLCPCB-Specific)
- Parts library:
https://jlcpcb.com/parts/componentSearch?searchTxt=<query> - Basic parts only:
https://jlcpcb.com/parts/basic_parts
BOM Format for Assembly
JLCPCB accepts CSV, XLS, or XLSX BOMs with these columns:
| Column | Required | Description |
|---|---|---|
Comment / Value | Yes | Component value (e.g., 100nF, 10k) |
Designator | Yes | Reference designators, comma-separated (e.g., C1,C2,C5) |
Footprint | Yes | Package/footprint name |
LCSC Part # | Recommended | LCSC part number (Cxxxxx) — guarantees exact match |
The column header for LCSC numbers must be exactly "LCSC Part #" or "LCSC Part Number" — typos cause upload failures.
KiCad BOM Export for JLCPCB
- In KiCad schematic editor, add an
LCSCfield to each symbol with the LCSC part number - Export BOM as CSV with columns: Reference, Value, Footprint, LCSC
- Rename columns to match JLCPCB's expected format:
- Reference -> Designator - Value -> Comment - Footprint -> Footprint - LCSC -> LCSC Part #
For gerber export settings, CPL format, and stencil ordering, see the bom skill.
JLCPCB Official API (Approval Required)
Apply at https://api.jlcpcb.com. Access is gated — requires review based on order history and business profile.
Available APIs (once approved):
- Components API — real-time pricing, inventory, component specs
- PCB API — upload gerbers, get quotes, place orders, track status
- Stencil API — stencil quoting and ordering
- 3D Printing API — SLA/MJF/SLM/FDM ordering
PCB Design Rules (JLCPCB Capabilities)
Standard PCB (1-2 layers)
| Parameter | Minimum |
|---|---|
| Trace width | 0.127mm (5mil) |
| Trace spacing | 0.127mm (5mil) |
| Via diameter | 0.45mm |
| Via drill | 0.2mm |
| Annular ring | 0.125mm |
| Min hole size | 0.2mm |
| Board thickness | 0.4-2.4mm (default 1.6mm) |
| Min board size | 6x6mm |
| Max board size | 500x400mm (2-layer) |
Multi-layer (4+ layers)
| Parameter | Minimum |
|---|---|
| Trace width | 0.09mm (3.5mil) |
| Trace spacing | 0.09mm (3.5mil) |
| Via diameter | 0.25mm |
| Via drill | 0.15mm |
| Board thickness | 0.6-2.4mm |
Importing DRU into KiCad
If you have a JLCPCB .kicad_dru design rules file, import it in KiCad Board Editor > Board Setup > Design Rules > Import Settings.
Assembly Constraints
Economic vs Standard Assembly
| Feature | Economic | Standard |
|---|---|---|
| Sides | Top only | Top + Bottom |
| Component types | SMD only | SMD + through-hole |
| Min component size | 0201 | 01005 |
| Fine-pitch BGA/QFP | Down to 0.5mm pitch | Down to 0.4mm pitch |
| Turnaround | ~3-5 days | ~3-5 days |
| Extended part fee | $3 per unique part | $3 per unique part |
General Constraints
- Minimum order: 5 PCBs for assembly
- Unique parts limit: No hard limit, but each extended part adds $3
- Basic parts: No extra fee, pre-loaded on machines
Rotation Offsets
JLCPCB's pick-and-place uses different rotation conventions than KiCad for some footprints. Common offsets:
| Footprint Family | Typical Offset |
|---|---|
| SOT-23, SOT-23-5, SOT-23-6 | +180° |
| SOT-223 | +180° |
| SOIC-8, SOIC-16 | +90° or +270° |
| QFN (all sizes) | +90° |
| SMA/SMB/SMC diodes | +180° |
| USB-C connectors | Varies — check datasheet |
To fix rotation issues:
- Add rotation corrections directly in the CPL file before uploading (adjust the Rotation column)
- For custom footprints, verify pin 1 orientation matches JLCPCB expectations
- JLCPCB's review step catches major errors, but subtle 180° rotations on symmetric parts (caps, resistors) may slip through
- After first assembly order, note any rotation corrections needed and apply them to future CPL exports
Ordering Workflow
Prototype Order (Bare PCB + Stencil)
- Export gerbers from KiCad (see
bomskill for export settings) - Upload gerbers to
https://cart.jlcpcb.com/quote— configure layers, thickness, color, qty - Add a framed stencil to the cart (uses paste layers from your gerbers)
- Order — PCBs and stencil typically arrive in ~1 week
Production Order (Assembled Boards)
- Export gerbers from KiCad (see
bomskill for export settings) - Export BOM as CSV with LCSC part numbers (format above)
- Export CPL (placement file) as CSV (see
bomskill for format) - Upload gerbers to
https://cart.jlcpcb.com/quote— configure layers, thickness, color, qty - Enable "PCB Assembly", select Economic or Standard
- Upload BOM and CPL files
- Review part matching — fix any unmatched parts by searching LCSC numbers
- Confirm and order
Tips
- Prefer Basic parts — no extra fee, always in stock, faster assembly
- Check stock before ordering — extended parts can go out of stock; use the
lcscskill to search - Panel by JLCPCB — for small boards, let JLCPCB panelize (cheaper) vs custom panels
- Lead-free solder — default is leaded (HASL); select lead-free HASL or ENIG if needed
- Impedance control — available for multi-layer boards, specify stackup in order notes
- Castellated holes — supported, enable in order options
- V-cuts and mouse bites — supported for panel separation
- Silkscreen minimum — 0.8mm height, 0.15mm line width for readable text
- Edge clearance — keep copper >=0.3mm from board edge (0.5mm recommended)