A PCB with contact fingers and solderable component lands may require different surface finishes in different places. Writing two finish names in a fabrication note does not identify where either process stops. The manufacturing review needs an unambiguous map of the finished surfaces and the permitted transition.
Start with the function of each exposed area
Identify connector contacts, solder lands, test contacts and other exposed copper separately. For each region, record the required finish and the product requirement it supports. Do not select a finish solely because its color resembles the neighboring region.
Eurocircuits describes a selective hard-gold route in which connector plating precedes the finish applied elsewhere. Its process illustrates why masking and operation sequence matter. The particular supplier’s sequence and limits must be confirmed for the actual order.
Draw the transition as a manufacturing feature
| Drawing item | Definition |
|---|---|
| Required region | Surface that must receive the named finish |
| Exclusion region | Surface where that finish is not permitted |
| Transition allowance | Agreed boundary tolerance or controlled overlap |
| Reference | Coordinates tied to the released board geometry |
Use the same viewing convention as the copper data. A mirrored bottom-side sketch can otherwise place a perfectly plausible finish boundary on the wrong contact group.
Review the masking route with fabrication
Ask the fabricator to identify the masking boundary and any access needed for the selective process. Review nearby holes and lands that could make the proposed division impractical. Resolve a conflict in the drawing rather than relying on an operator to choose the less inconvenient interpretation.
For example, a solder land close to the contact-finger zone should remain recognizable as a separate requirement. If the fabricator needs more separation, compare a geometry change with an approved process alternative before releasing either.
Inspect each region and the boundary
- Check that the correct surfaces received their specified finish.
- Measure required properties using the appropriate location and method.
- Inspect the transition against its agreed definition.
- Retain the approved region map with the job data.
A report taken from one convenient finish area cannot establish the condition of every other area. Similarly, a good connector mating result does not establish solderability of adjacent lands.
Keep the finish map synchronized when the connector location or board outline changes. A small mechanical revision may move the required boundary even if the finish names remain identical in the ordering system.
The plating-bus guide covers temporary conductive connections, while surface finish planning helps define the purpose of each final surface.
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