Elecrow SMT Pick-and-Place Programming Checklist

Pick-and-place programming is the step that converts a design release into machine-ready SMT data. A clean centroid file and a verified BOM are not enough if feeder assignments, rotation conventions, panel coordinates, and no-population rules are ambiguous. Small errors in this stage become placement defects, rework, or a line stoppage that costs far more than the engineering time needed to validate the program up front.

This Elecrow SMT pick-and-place programming checklist helps design and manufacturing teams prepare data that an assembly line can run with minimal clarification. It covers file integrity, panel alignment, package verification, feeder planning, first-article validation, and documentation handoff. Use it before submitting a PCBA order or releasing a new revision to production.

Confirm the baseline manufacturing package

Start with a locked release set. The pick-and-place program must reference the same PCB revision, BOM revision, assembly drawing, stencil data, and panel drawing. If any of these files drift independently, the machine may place the correct part on the wrong board location or populate a designator that engineering marked as DNP.

Collect these inputs before programming:

• Centroid or XYRS file: Designator, X/Y coordinates, rotation, and side for every populated location.
• BOM: Manufacturer part number, package, value, and mounting type for every designator in the placement file.
• Assembly drawing: Top and bottom views with polarity, pin one, and unusual placement notes.
• Panel drawing: Array count, fiducials, breakaway method, tooling holes, and edge rails.
• PCB fabrication output: ODB++, Gerber, or equivalent data confirming finished board dimensions.
• Special process notes: Adhesive, selective solder, post-reflow install, moisture-sensitive handling, and programming requirements.

Assign a single build name to the release. Avoid filenames such as “final_v3_new” without a revision table. The SMT engineer should be able to identify which product, variant, and PCB revision the program supports without opening every source file.

Validate centroid data before import

Centroid exports vary by EDA tool. Some use board origin at a corner; others center the board or use a panel origin. Rotation may be defined clockwise or counterclockwise. Units may be millimeters or mils. Before importing into the pick-and-place system, normalize units, origin, and rotation convention in a controlled spreadsheet or CAM step, then compare the result against the assembly drawing.

Check every populated designator

• Every BOM line marked as fitted appears in the centroid file with a unique coordinate.
• Every centroid entry maps to a valid BOM line with a purchasable manufacturer part number.
• DNP, test points, and mechanical placeholders are excluded from the active program variant.
• Top-side and bottom-side entries are separated and labeled consistently.
• No duplicate designators exist unless the panelization intentionally repeats boards with renamed references.

Verify rotation on polarized and asymmetric parts

Diodes, LEDs, tantalum capacitors, electrolytics, connectors, QFNs, BGAs, and ICs with pin one at a corner require explicit rotation validation. Do not assume the EDA default matches the machine library. Overlay the centroid plot on the assembly drawing and mark pin one for every non-symmetric package. For LEDs, confirm whether rotation refers to cathode mark, cathode pad, or package notch as seen on the reel.

Compare the first article image with the programmed rotation before approving high-volume production. A 180-degree LED rotation may solder perfectly yet fail optical or color bin requirements.

Match packages to machine libraries

The pick-and-place program depends on accurate package definitions: body size, lead type, pitch, pickup point, vision mode, and nozzle selection. A BOM line that says “0402” is insufficient if the actual part uses a metric 1005 body with nonstandard height. Import manufacturer recommended land pattern dimensions and compare them with the physical sample or data sheet when a package is new to the line.

• Confirm metric versus imperial size codes for all passives.
• Verify height restrictions for large components near small ones on dense boards.
• Check bottom-terminated packages for vacuum pickup feasibility and vision features.
• Define special handling for connectors, shields, modules, and odd-form parts.
• Record whether a part uses embossed or punched tape and the required feed pitch.

When a part is not in the standard library, create a controlled custom footprint entry with photo verification on first article. Do not copy a “similar” package to save setup time. Similar body sizes with different lead geometry cause chronic misplacement or tombstoning.

The SMT inspection methods guide explains how first-article verification and AOI can catch package and rotation issues before they spread through a lot.

Plan feeders, packaging, and attrition

Programming is not only coordinates. It includes how each component reaches the machine. Map every BOM line to an expected packaging format: paper or embossed tape, reel width, tape pitch, tray, tube, or cut tape. Identify lines that require feeder adapters, bulk feeding, or manual install after reflow.

Feeder assignment checklist

• Reel width and pitch match the physical packaging for every SMT line.
• High-count passives are grouped to reduce feeder changes where practical.
• Large or heavy components have appropriate support and placement speed limits.
• Nozzle sizes are assigned per package family and verified on first pickup.
• Attrition and scrap allowance are included in kit quantity calculations.
• Moisture-sensitive devices have documented open-time and bake requirements before loading.

For double-sided PCBA, sequence the program with the correct side-first rule and adhesive requirements if the design needs them. Confirm that bottom-side components will not detach during top-side reflow. Tall parts on the first side may constrain second-side stencil clearance and must be flagged before programming is finalized.

Program the panel, not only the single board

Production SMT runs on panels. The pick-and-place file must use panel coordinates if the board is assembled in an array. Confirm fiducial locations, panel origin, and whether the program expects boards pre-routed or still in a solid panel. Missing or misplaced fiducials force manual alignment and reduce placement accuracy on fine-pitch parts.

Review breakaway tabs, mouse bites, and rail width against machine rail limits. Components too close to panel edges may require placement offsets or modified panel design. If a board is depanelized before test, ensure test pads and connector access remain reachable after separation.

Fiducial and alignment requirements

• At least two global fiducials per panel side, positioned asymmetrically when required by the line.
• Local fiducials for fine-pitch ICs when the process requires them.
• Fiducial clearance free of silkscreen, vias, and copper features that confuse vision.
• Panel orientation arrow on the drawing matches the programmed conveyor direction.

Define variants and no-population rules explicitly

Do not rely on verbal notes for build variants. Create separate programs or controlled variant tables for each released configuration. A variant column in the BOM should map directly to enabled or disabled placements in the machine data. Mixed variants on one panel are possible but must be designed and programmed intentionally, not improvised on the line.

Document which designators are intentionally omitted, which are install-by-hand, and which are populated only on certain serial-number ranges. If firmware or calibration depends on a populated option, tie the variant name to test and programming instructions. An incorrect DNP decision can pass visual inspection yet fail functional test.

Run a first-article programming validation

Before full production, run a first article with complete process chain: paste print, placement, reflow, and inspection. Programming validation is more than watching the machine place parts. It confirms that pickup, vision recognition, placement pressure, and solder joint formation are acceptable for every unusual package on the board.

• Capture placement images or AOI results for all polarized and fine-pitch parts.
• Verify thermal pad components for sufficient paste and acceptable placement offset.
• Inspect BGAs and QFNs with X-ray when required by the design class.
• Compare actual component markings and orientations with the assembly drawing.
• Record nozzle, feeder, and vision settings that produced acceptable results.

Link first-article results to the approved program revision. If a nozzle change or vision threshold adjustment fixes a chronic misplacement, update the program documentation so the next build does not rediscover the same issue.

For reflow-sensitive packages, coordinate programming validation with oven profile approval. The SMT reflow profile optimization guide describes how placement and thermal process interact on mixed PCBA builds.

Document the approved program release

An approved pick-and-place program should be reproducible by another engineer on another shift. Store the machine export, source centroid file, BOM revision, panel drawing, feeder map, nozzle list, and first-article approval record together. Include photos of nonstandard packages and any custom lead forms.

Minimum release record

• Product name, PCB revision, BOM revision, and program file name.
• Machine model, software version, and panel orientation.
• List of custom packages and vision parameters.
• Feeder map with reel identifiers or lot traceability links where required.
• First-article approval signature and date.
• Known limitations, manual install steps, and post-reflow operations.

When engineering releases a new PCB or BOM revision, treat programming as a new release. Do not edit coordinates in the machine without updating the controlled source files. Silent on-machine edits are a common cause of revision drift between design documentation and production reality.

Prepare a complete Elecrow handoff package

Elecrow SMT programming proceeds faster when the customer supplies coherent data and explicit notes. In addition to centroid and BOM files, provide assembly drawings, panelization intent, approved alternates, and any validated constraints from prior builds. Highlight parts with known supply substitutions, bottom-side adhesive needs, or height keep-out restrictions.

If the customer supplies consigned material, include reel photos or labels showing tape width, pitch, and orientation. Mismatch between purchased packaging and programmed feeder expectations is a frequent source of setup delay. For turnkey builds, ensure the BOM lists exact manufacturer part numbers and packaging codes suitable for automated feeding.

Review the PCBA BOM readiness checklist before upload. Clean data reduces back-and-forth and helps Elecrow quote lead time accurately.

Final pre-production checklist

Walk through this list immediately before releasing the SMT line for volume production:

• Centroid, BOM, assembly drawing, and panel drawing share one revision identifier.
• All rotations and polarities are verified on first article.
• Package libraries match physical components and pickup trials.
• Feeder map, packaging, and attrition quantities are complete.
• Variants and DNP rules are encoded in controlled program data.
• Fiducials and panel orientation match the physical panel.
• First-article inspection and any required X-ray are approved.
• Program release documentation is stored with the manufacturing record.

Pick-and-place programming is detailed work, but it is also one of the highest-leverage steps in SMT. A disciplined checklist prevents expensive defects and keeps PCBA builds on schedule. Submit files through the Elecrow shop, browse related guides on the Elecrow blog, or contact Elecrow if your design includes nonstandard packages that need engineering review before programming.