PCB and Transmission Lines
Model class: Exact ideal relationship
Solder-mask sliver and expansion planner
Calculate the remaining solder-mask web between two facing pads after entered mask expansion on each side.
Interactive engine
Start with the stated conditions.
Values stay in this browser. Choose a representative scenario, then calculate deliberately.
Example ready
Calculate to inspect the result.
The result will identify the direct answer, assumptions, and any warning that changes the next decision.
Assumptions to check
- The entered solder-mask-planner values represent the stated operating condition.
- This exact ideal relationship is evaluated in the declared lumped or first-pass model.
- A solder-mask-planner calculation is not a component qualification or safety approval.
What this solder-mask-planner calculation establishes
Calculate the remaining solder-mask web between two facing pads after entered mask expansion on each side. The useful result is the stated electrical quantity and the decision it supports, not an unstated claim about a finished product. This engine keeps the governing relationship visible so an input, unit, condition, or model boundary can be reviewed before a value becomes a component or layout choice.
Remaining mask web is the copper-to-copper gap minus twice the entered mask expansion (once per facing side). Treat the number as a first-pass result for the declared operating point. When a source, load, temperature, frequency, waveform, component tolerance, or measurement condition changes, repeat the calculation at the relevant corner rather than assuming the nominal answer persists.
Worked decision context
Two pads with a 0.20 mm copper gap and 0.05 mm mask expansion on each facing side leave a 0.10 mm nominal mask web. That example verifies the equation and illustrates the scale of the result, but it does not select a part by itself. Compare the result with available values, ratings, tolerance bands, and the receiving circuit or physical environment before implementation.
Use the primary output to identify the binding constraint. If it leaves little margin, document which input dominates and use selected-part data, a higher-fidelity model, simulation, or measurement. This is especially important when a small numerical difference changes a thermal, timing, noise, or reliability decision.
Limits and validation handoff
Compare the result with the fabricator's minimum solder-mask sliver rule for the selected mask type before finalizing footprint spacing. The calculation does not silently include omitted parasitics, installation conditions, manufacturing variation, or product policy. Those conditions can be decisive even when the arithmetic is exact for the selected model.
Record inputs, units, model assumptions, and the intended decision with the result. Verify the leading risk against the selected component data sheet and a representative measurement when the circuit has consequential energy, high voltage, safety, compliance, or reliability requirements.
Common mistakes
- Treating the solder-mask-planner result as a guaranteed operating limit rather than a first-pass exact ideal relationship estimate.
- Mixing a data-sheet value measured under one condition with this solder-mask-planner calculation performed at another.
- Selecting a component before checking the boundary this calculation names: compare the result with the fabricator's minimum solder-mask sliver rule for the selected mask type before finalizing footprint spacing.
Model limit and handoff
Keep the entered solder-mask-planner conditions with the calculation, then validate the binding limit using the selected component, physical implementation, and representative operating corner.
FAQs
Is this solder-mask-planner result sufficient to approve a design?
No. It applies exact ideal relationship reasoning to the entered solder-mask-planner values and names the checks that still need selected-part data, a higher-fidelity model, or measurement. Compare the result with the fabricator's minimum solder-mask sliver rule for the selected mask type before finalizing footprint spacing.
What does this solder-mask-planner calculator assume that could make the result wrong?
Remaining mask web is the copper-to-copper gap minus twice the entered mask expansion (once per facing side). If the entered values do not match the real operating condition, the result no longer describes the actual circuit.
Where should this solder-mask-planner result go next?
Compare this solder-mask-planner result with PCB fabrication and standards handoff, then use the stated next decision below the calculator to move from this first-pass number toward an implementation.