Identify the purpose of each opening
Separate solderable pads, connector fingers, test points, and deliberately exposed conductors. Each has a different access or contamination concern. Review pad transitions at the same time as opening geometry. State the usable exposed area required by the joining process instead of supplying an unexplained expansion copied from a rigid-board rule.
Opening requirements by use
| Design input | Question to resolve | Review output |
|---|---|---|
| Solder pad | What area must remain joinable? | Exposed-area and assembly review |
| Contact finger | Where must the contact travel remain clean? | Connector drawing and exclusion boundary |
| Test point | Can a supported probe reach it? | Access and probing arrangement |
| Grouped opening | What adjacent copper becomes exposed? | Electrical and handling review |
Account for the assembled material system
Identify the coverlay film, adhesive, bonding side, and neighboring features. The coverlay material guide explains why the adhesive belongs in the construction record. Discuss registration, adhesive flow, and practical opening formation with the fabricator. Keep proposed allowances visible until agreed; this page does not provide a universal clearance or minimum opening size.
Check contacts and assembled joints separately
For a mating terminal, reference the connector drawing and define any adhesive-exclusion area. For a soldered component, check joining access, paste geometry where relevant, and inspection visibility. Compare the final copper and coverlay outputs in a viewer. Include representative opening inspection in the first build before accepting a recurring production setup.
Before you release the design
- Label coverlay layers and their viewing side unambiguously.
- Review film and adhesive as separate stack contributions.
- Overlay openings with copper and local stiffeners.
- Agree critical exposed-area checks before release.
Watch points
- A solder-mask layer name alone may not communicate a physical coverlay process.
Practical questions
Should every pad have its own coverlay window?
Choose individual or grouped openings with the fabricator and assembly team. Access, registration, exposed conductors, and manufacturing method determine whether a candidate arrangement is appropriate.
Can I assume adhesive stops at the drawn edge?
No. Discuss the material and process behavior, then specify the functional exposed or exclusion area and its agreed tolerance.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.