Pick and Place File Guide — Centroid Files for SMT

The File Your SMT House Needs

Every SMT-assembled PCB requires a pick-and-place (PnP) file alongside Gerber and BOM. Without it, the assembly machine has no way to know where each component goes. Yet PnP file generation is the most error-prone step in the design-for-assembly workflow — wrong rotation conventions, missing through-hole filters, and origin offset mistakes are responsible for most first-order assembly failures. This guide covers KiCad, Altium, Eagle, and EasyEDA PnP export plus how to verify before submission.

What's in a Pick and Place File

A pick-and-place file (also called centroid file, .pos, .cpl, or .csv) is a CSV listing every SMT component with: reference designator (R1, U2), X coordinate of component center, Y coordinate, rotation angle (0/90/180/270), layer (top or bottom), and optional footprint name. The SMT machine reads coordinates relative to the panel's fiducial origin, so coordinate-system definition matters as much as the values themselves. Standard column order varies by tool: KiCad's default differs from Altium's default differs from JLCPCB's expected format.

What This Guide Covers

• KiCad .pos export — Auxiliary Axis origin, top/bottom file split, JLCPCB rename convention.
• Altium CPL — IPC-7351 compliant rotation, file naming, JLCPCB compatibility.
• Eagle .mnt — mountsmd.ulp script, ASCII-to-CSV conversion, layer separation.
• EasyEDA centroid — JLC-compatible export, direct submission workflow.
• Rotation correction — JLC's per-package offset table, common SOT-23/QFN fixes.
• Through-hole filtering — separating SMT from through-hole, hand-place workflow.

How to Verify Pick and Place

1. Open pcbviewer.app and drop your PCB file. Components render in 3D with their orientation visible.
2. Open the BOM panel. The Designator + Footprint columns help spot rotation errors before SMT submission.
3. For each part, verify the 3D orientation matches the manufacturer's datasheet pin 1 marker.
4. Cross-check against JLC's library footprint preview (jlcpcb.com/parts/<LCSC code>) for rotation offset.
5. For first-time SMT orders, request a placement preview from the assembly house before fabrication starts.

Why PnP Errors Are Expensive

A wrong rotation in your CPL file means the SMT machine places parts at the wrong angle. The error isn't caught until visual inspection or first-power-on, by which point the entire panel is wasted. JLCPCB's setup fee for SMT is $8 per board type — repeat that across 5 prototype boards and a single bad CPL file costs $40 plus a week of lead time. Verifying orientation in a 3D viewer before submission prevents the most common assembly failure mode at zero additional cost.

When PnP Files Show Up

• JLCPCB SMT — required input for every assembled order, validated by their BOM tool
• PCBWay assembly — same role, slightly different column order convention
• In-house SMT — your factory's machine reads PnP for production runs
• Contract manufacturer quote — assembly houses use PnP to estimate placement time and quote
• Manual assembly — fabricators use PnP to print rework guides for hand-placed prototype boards

Browser-Side Parsing, No Upload

PCB files contain proprietary product designs. MakerSuite 3D parses files entirely in your browser; no server upload, no cached copy. Component positions, rotations, and reference designators stay on your machine. Safe for NDA reviews and pre-release product workflows where the assembly process discloses sensitive engineering choices.