A solder mask thickness value is useful only when its measurement location is defined. A board presents copper surfaces, spaces between conductors and transitions around edges. Two reports can use the same units while measuring different parts of that geometry.
Turn the requirement into a location
Mark the relevant region on the design or a representative cross-section drawing. State the underlying surface and the direction of the measurement. If a requirement applies to several types of location, list them separately rather than combining their results into one average.
Taiyo’s product information lists different mask variants and application methods. Agree thickness using the exact approved material and its current technical documentation; a product-family name does not define the measurement location or acceptance requirement for a finished board.
| Definition field | Question to resolve |
|---|---|
| Board region | Which feature or coupon represents the requirement? |
| Underlying surface | What lies directly beneath the measured mask? |
| Material state | At which completed processing stage is it measured? |
| Method | How is the boundary located and the distance determined? |
| Reporting | Which individual values and locations are retained? |
Check comparability before judging variation
Use consistent sample preparation and measurement definitions for supplier and customer reports. If their methods differ, establish what comparison is valid before declaring one result wrong.
For example, a measurement above a broad conductor and another in a space between conductors should not be averaged as though they were repeat readings at one location. Keep the geometry distinction visible in the report.
Connect the value to the actual concern
Identify whether the inquiry concerns a drawing limit, assembly interface, coverage or another product requirement. Thickness alone does not establish adhesion, cure or every property relevant to that concern.
When investigating a local defect, preserve photographs and section locations before making additional cuts. A later section through a different part of the feature may not reproduce the original observation.
Close the measurement agreement
- Approve the location and material-state definition.
- Record the method and its relevant limitations.
- Measure representative features.
- Compare individual results with the applicable requirement.
- Retain the definition for repeat orders and disputes.
A concise annotated drawing can prevent more confusion than a long specification containing an unexplained minimum number. The reviewer should be able to point to the same physical distance on every sample.
Keep measurements from intentionally different locations in separate groups. If a local thin area is relevant to acceptance, a thicker neighboring area should not conceal it through an overall average that the drawing never authorized.
The mask process-record guide supports material-state identification, and adhesion evidence review keeps a separate property from being inferred from thickness.
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