Checking Paste Outputs for Do-Not-Populate Variants

Marking a component do-not-populate does not automatically determine whether its pads should receive solder paste. Different CAD export settings and production strategies can produce different results. Make the paste decision explicit for each assembly variant and verify the files that the stencil supplier will receive.

Understand what the variant controls

Altium’s documentation distinguishes fitted, not-fitted, and alternate components, and describes a separate option for allowing paste-mask variation. This illustrates why a correct variant BOM does not prove that the paste output matches it. Review the settings in the software version used by the project. Altium: variant and paste-mask controls.

List the unpopulated reference designators and their purpose: optional functions, tuning positions, test features, or mutually exclusive components. Discuss whether the assembly will use one shared stencil or variant-specific stencils. That choice affects both production control and the state of the unused pads.

Review the physical consequences

• Check whether unused pads are near other joints or mechanical interfaces.
• Identify positions intended for later manual fitting or tuning.
• Consider inspection and test access to unpopulated features.
• Confirm that overlapping alternate footprints are handled intentionally.
• Record the approved paste treatment for each relevant feature group.

For example, two alternative component footprints may share a local region. Removing one component from the placement file while leaving all paste apertures active can create an assembly condition the designer never reviewed. The correct solution depends on the chosen variant and process, not on a universal rule that all DNP pads must be bare.

Compare the generated documents

Open the paste layers, placement list, BOM, and assembly drawing for the same named variant. Check a sample of fitted and unpopulated positions, including the most complex alternates. Confirm that filenames and title blocks identify the variant consistently. Do not infer correctness from the active CAD view alone; output jobs can have their own variant settings.

Control shared tooling carefully

If a shared stencil is intentionally used, document that decision and the conditions it creates on unused pads. Keep the stencil identity associated with the approved assembly variants. If variant-specific tooling is required, ensure production can distinguish it before printing.

Recheck the outputs when a component changes status or an alternate footprint is added. A variant is a controlled assembly configuration, not just a purchasing filter. The release should make the intended paste, placement, and final populated state agree so the assembler does not need to resolve the design choice on the line.