A BOM grouped only by value and footprint can merge components that must be purchased differently. Two resistors may share resistance and package while differing in tolerance or an approved manufacturer option. Define grouping around the project’s controlled purchasing identity, then verify the exported rows.
Altium’s BOM Report Manager documentation describes configurable columns and grouping. Review the settings used for the actual export; the way a source table looks on screen is not sufficient evidence of the report’s grouping behavior.
Choose the identity that governs a row
Determine whether the BOM uses an internal part number, a manufacturer orderable number, or another controlled identifier. If an internal part permits several alternatives, show that relationship explicitly instead of mixing uncontrolled manufacturer choices into a single description.
Include the attributes needed to distinguish approved parts and assembly variants. A free-text value field is useful for reading the circuit, but it is rarely sufficient to define every purchasing requirement. Resolve inconsistent spelling and units in source data before trying to hide differences through report formatting.
Inspect merge and split cases
| Case | Question |
|---|---|
| Same value and footprint, different approved identities | Do they remain separate? |
| Same approved identity, different descriptions | Is the split intentional or a source-data error? |
| Alternative approved parts | Is the permitted substitution relationship clear? |
| Variant-specific population | Are quantity and references correct for this build? |
Compare grouped quantities with the expanded reference list. Every fitted reference should contribute exactly once to the appropriate row, while intentionally omitted positions should follow the defined variant policy. A total component count alone cannot reveal an incorrectly merged pair of rows.
Use controlled export examples
- Select representative components that should merge.
- Select similar components that must remain separate.
- Generate the intended production BOM.
- Inspect identifiers, quantities, and designators.
- Reimport or parse the file using the downstream workflow.
Check the actual exported file, including spreadsheet templates and post-processing scripts. A correct source grouping can be damaged by a later formula or a cleanup operation that removes suffixes. Retain full orderable numbers when those are part of the approved identity. Check blank identity fields explicitly; missing data should not cause unrelated components to collapse into one purchasing row.
Close the review with the grouping definition and a reconciled BOM. Explain any intentionally separate rows that share the same purchasable component, such as different assembly stages. The BOM and placement reconciliation guide provides the next check between those rows and the assembly coordinate data.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist