KB: Multi-board Assembly Import Fails Due to Corrupted STEP Files

Solution Details

Assembly Import Errors and Unexpected Exits

This issue affects the physical Multi-board Assembly creation process rather than the logical Multi-board Schematic design stage. Users may encounter one or more of the following symptoms when importing a PCB into a Multi-board Assembly:

• An ECO Action Failed error is displayed during the import process.
• An AddBoardSuperassembly failed error appears when importing the board.
• Altium Designer closes unexpectedly without displaying an error message.
• The Multi-board Assembly cannot be created successfully.

Corrupted STEP Geometry Interrupts Import Processing

The issue is caused by one or more corrupted STEP files referenced by the PCB. During Multi-board Assembly creation, Altium Designer loads the physical representation of referenced PCBs and their associated 3D model data into the assembly environment. If a STEP file contains invalid or corrupted geometry, the import operation may fail while processing the model data. As a result, Altium Designer may display an error, terminate unexpectedly, or fail to create the Multi-board Assembly. Because the issue originates from the STEP model itself, the behavior can occur regardless of the Altium Designer version being used.

Validate and Replace External 3D Models

• Identify and replace any corrupted STEP files associated with the PCB.
• Validate all externally referenced 3D model files used by the PCB, not only the primary board STEP model.
• Re-export affected models from the original MCAD source before retrying the import.
• Review Multi-board Assembly import settings if additional troubleshooting is required.

Re-export STEP Models and Retry Import

1. Identify the STEP file associated with the PCB being imported into the Multi-board Assembly.
2. Open the original mechanical design in the MCAD application used to create the model (for example, SolidWorks).
3. Re-export the 3D model as a new STEP file.
4. Replace the existing STEP file in the Altium project with the newly exported file.
5. Reopen the project in Altium Designer.
6. Import the PCB into the Multi-board Assembly again.

Additional Notes

• The issue is independent of the Altium Designer version.
• If similar symptoms occur, validate external 3D model files early in the troubleshooting process.
• A successful STEP file re-export can often resolve geometry-related import failures without requiring project modifications.
• Multi-board Assembly import preferences may be useful when isolating import-related issues by controlling which PCB objects are imported into the assembly.

References

• Creating the Physical Multi-board Assembly
• Designing with Multiple PCBs
• Multi-board Assembly Preferences