Engineering preparation 路 Pick and Place File
Pick-and-place files: make every coordinate interpretable
Check placement CSV units, origin, rotation and board side. Inspect coordinates locally, then verify the release against the actual footprint and assembly drawing.
Start with the files you have. The tool is optional; open questions can be reviewed before quotation.
What is a pick-and-place file?
A pick-and-place file lists the position, rotation and board side of each component to be placed. It is also called a centroid file, component placement list, CPL or XY file. The file supports assembly preparation, but the receiving team must interpret its coordinate origin and rotation conventions against the released board and component information.
A BOM answers what belongs on the board. A placement file answers where its references are located. Gerber data describes board features and artwork. None of these files should silently replace another. Use the PCB assembly file checklist to release a consistent set rather than exporting each document on a different day.
Most avoidable placement questions are not caused by missing decimal precision. They arise from mismatched variants, an unstated unit, a different origin, a bottom-side transformation or an incorrect relationship between footprint zero and physical pin 1. This page helps you identify those questions before a program is approved.
Essential fields and a readable example
There is no single column spelling accepted by every assembler. Agree the export format with the receiving team. A plain CSV can be useful because references and numbers are visible, but the file must retain its units, decimal separator and coordinate interpretation. A spreadsheet that looks aligned on screen may still export extra separators or reformatted values.
| Field | Example | Review question |
|---|---|---|
| Reference | U1 | Does this exact reference exist in the fitted BOM? |
| X | 30.000 | Relative to which origin, in which units? |
| Y | 20.000 | Is positive Y defined consistently? |
| Rotation | 90 | What does zero mean for this footprint? |
| Side | Top | How are bottom-side coordinates represented? |
| Value / package | Optional supporting fields | Does the footprint match the approved device? |
Use one component reference per placement row. Grouping R1 and R2 into one BOM line can be appropriate; grouping them into one XY location is not. Mechanical items, fiducials and through-hole parts may need different treatment. State what the exported placement list includes rather than assuming every object on the board requires automatic SMT placement.
Inspect coordinates without uploading a design
Paste CSV data or read a local CSV file. Select the coordinate units, enter the board鈥檚 X and Y dimensions, and locate the file origin relative to the board鈥檚 lower-left corner in millimeters. The checker flags duplicate references, invalid fields and component origins outside that rectangle. It also separates top and bottom counts and offers a selectable coordinate preview.
Pick-and-Place Coordinate Checker
The displayed arrow represents the numeric angle only. It is not a picture of the real package, nozzle or pin-1 position. The preview does not read Gerber files, detect collisions or prove that the board outline is rectangular. Negative coordinates can be legitimate if the declared origin is outside the board; the entered offsets determine where they appear in this planning view.
Units and origins: use one explicit transformation
If a coordinate file uses inches, 1.0 represents 25.4 mm. If it uses mils, 1.0 represents 0.0254 mm. Choosing millimeters for an inch export can produce a compact-looking cluster that is wrong by a large scale factor. Never infer the unit from the apparent size alone; read the export setting and record it with the file.
The tool uses a simple, disclosed transformation: plotted X equals the input X multiplied by the unit conversion factor, plus the X origin offset. Y follows the same rule. The offsets locate the file鈥檚 zero point relative to the entered board rectangle. They do not rotate, mirror or repair the source file.
For example, a part at X = 1 inch and Y = 0.5 inch becomes X = 25.4 mm and Y = 12.7 mm when both offsets are zero. If the file鈥檚 origin is 5 mm to the left of the board鈥檚 left edge, its X offset is 鈭�5 mm and that part plots at 20.4 mm. Confirm this interpretation with identifiable board features.
Keep the drill, artwork and assembly outputs registered to the agreed datum. A panel may use a panel origin while a unit-level placement file uses a board origin. Both can be valid, but the relationship must be supplied. Discuss rail width, unit spacing and the assembly datum through the panelization guidelines.
Rotation and bottom-side data need visual confirmation
An exported angle does not, by itself, establish the physical orientation of a component. Library authors define footprint orientation, and the assembly process also has package and feeder conventions. A square package can look correct after a 90-degree error while its electrical connections are completely wrong. Review pin 1, polarity and the land-pattern drawing.
Bottom-side conventions need particular care. A file may already express the transformation expected by its exporter or the receiving system. Adding an extra mirror because the component is on the bottom can produce a second, incorrect transformation. The checker therefore retains a common declared XY frame and applies no automatic bottom mirroring.
Ask the assembler how the bottom-side data will be viewed and interpreted. Confirm at least one asymmetric, polarized or clearly numbered part on each populated side against the released assembly drawing. Document the agreed convention instead of editing a whole column of angles until a preview appears plausible. A visually pleasing plot is not a substitute for that agreement.
Resolve LED direction before applying angles
An LED angle is only meaningful with its library zero and viewing convention. Use the LED polarity and placement workbench to explain the terminal map, then reconcile the production export with the assembly system.
Worked review: D1 is on the bottom of the board and its placement row says 0掳. The row does not tell a reviewer where the cathode should face. Resolve the record in this order:
- Match D1 to its full part number and identify anode and cathode from that device鈥檚 datasheet.
- Match those terminals to the footprint pad numbers and the released assembly drawing.
- State whether the drawing and receiving placement view are looking from the top or bottom; confirm the exporter鈥檚 bottom-side convention.
- Check the interpreted D1 position with the assembler, then retain that agreement with the release files.
Do not add 180掳 to every bottom-side part to make this one example look right. An offset valid for one footprint and receiver convention does not establish a correction for the whole board. If the reference drawing and export disagree, flag D1 and the exact file revision before programming is released.
Export deliberately from the EDA project
Use the manufacturing or fabrication output function for the released PCB and variant. The describes placement-file generation and relevant options for its documented version. Read the documentation for your installed version because dialog labels and handling of component attributes can differ.
In Altium workflows, check the output job and chosen variant rather than assuming the editor鈥檚 current view controls every generated file. The official provides the reference point for those settings. Reopen the exported text and compare it with the board you intended to release.
A repeatable procedure is to freeze the design revision, choose the assembly variant, export the BOM and placement data, generate the assembly drawing, and record the output settings. Review the fitted references and polarity indicators. Store the package together with an explicit release status. If the board changes, regenerate the affected outputs and identify the superseded revision.
The machine-preparation team may transform engineering data into equipment-specific programming. That does not mean the customer鈥檚 file should be guessed or repaired without review. Confirm any interpretation that changes component identity, side or orientation. Refer to the assembly process for where placement preparation fits between material readiness, paste printing and reflow.
Reconcile the fitted reference set
Compare references, not just total line counts. Two files can both contain 120 rows and still disagree because one contains R37 while the other contains R73. Normalize harmless spacing or case differences for comparison, but preserve the original release files. Investigate missing, duplicated and extra references separately.
A DNP item in the design BOM may be absent from the placement export, depending on the chosen convention. That is not automatically a mistake. A fitted device that has no placement record, or a placement record for an intentionally unpopulated option, needs an explanation. Use the DFA consistency checker for a cross-file comparison and the BOM guide for purchasing fields.
Check that the coordinates refer to the intended footprint origin. A connector鈥檚 CAD origin, mechanical center and placement pickup point may differ. Where the package or assembly method needs special handling, include the relevant drawing and instruction. The CSV checker cannot establish those physical relationships from numbers alone.
What to send for placement review
Send the placement file with units and export settings, the matching BOM, the approved board data and an assembly drawing showing polarity. Identify the board revision, variant and whether the coordinates describe one unit or a panel. Call out unusual packages, bottom-side interpretation and any references intentionally excluded from automatic placement.
If you have only Gerbers and a BOM, say that placement data is unavailable. Reconstructing a machine-preparation file from artwork is a separate task and needs validation; it should not be represented as an original CAD export. Early disclosure is more useful than supplying a plausible but unverified coordinate list.
The next useful step is a file-based engineering conversation. Attach the checker鈥檚 findings and the source files separately, identify the open convention and ask for confirmation before production programming is approved. No confidential CSV is uploaded by the local tool, and its output is not automatically sent to Contact.
Pick-and-place file questions
Are centroid, CPL and XY files the same?
They commonly describe the same placement task, but their fields and conventions can differ. Confirm the required structure, units, origin, board side and rotation interpretation with the receiving assembler.
Does a zero-degree rotation always mean pin 1 is in one corner?
No. Zero depends on the footprint and data convention. Check the component documentation, library definition and assembly drawing. The numerical preview cannot infer an electrical pin map.
Can I combine both board sides in one CSV?
Yes, when the agreed format explicitly records the side and its coordinate convention. Separate files may also be accepted. The important point is consistent interpretation and traceability to the released variant.
Does passing the rectangle check prove correct placement?
No. It only checks parsed positions against the dimensions and offsets you entered. It does not verify body clearances, pad geometry, physical orientation, design intent or manufacturing capability.
Ask about placement files
Send the board revision, quantities and available files. Identify what is confirmed and what needs engineering advice. You can attach the tool review manually with the approved source files.
Contact opens a separate form. Tool entries are not transferred automatically. Technical references reviewed September 2026; photographs show published process context, while diagrams are explanatory illustrations.