Copper-filled microvias use deposited copper to build the interlayer connection and fill the opening. The completed feature must satisfy electrical, geometric and interface requirements. “Copper filled” is not a complete acceptance specification and should not be treated as proof that every internal interface is sound.
Describe the finished requirement
Identify the layer span, hole geometry and required surface condition. Where a subsequent via lands above the filled feature, show the arrangement in the construction drawing. Where the feature sits in a solder pad, coordinate the surface requirement with assembly.
The process depends on the opening and target preparation as well as the deposition step. Ask the fabricator to explain how its proposed sequence supports the actual construction. Avoid drawing conclusions from the plating chemistry or equipment name alone.
Fill review checklist
| Feature | Question to resolve |
|---|---|
| Target interface | How is the landing surface prepared and represented in acceptance evidence? |
| Internal fill | Which defects and criteria are evaluated under the project specification? |
| Surface condition | What is required for the next layer or soldering operation? |
| Representative structure | Does the coupon match the demanding production arrangement? |
Distinguish inspection from performance
A section can reveal the sampled geometry and visible internal conditions. Performance testing can provide evidence about the connection under a defined exposure. Agree how these forms of evidence complement each other for the product rather than treating one as a universal substitute for the other.
An illustrative stacked construction should be reviewed as a path through multiple interfaces, not just as separate filled holes. Record which arrangement was tested and whether the results represent the proposed production material and process.
Preserve the approved process assumptions
Specify which changes to fill route, material or via arrangement require customer review. A proposed substitution may preserve the external pad appearance while changing the internal construction. It should enter the change process before production.
Atotech's published plating information provides examples of industrial copper-processing technology. It does not establish that this website's operator owns those systems or supports their advertised limits. Request current construction-specific evidence and an exact quote for the released data. Verified copper-filling capabilities, acceptance specifications and production equipment remain [NEEDS CLIENT INPUT].
Continue the engineering review
- Via-in-pad filling and plating
- Microvia reliability and thermal exposure
- HDI microsection and performance testing
- HDI PCB engineering hub
Source checked October 2, 2026: Atotech copper-plating process information. Supplier literature is context, not a claim of this site’s equipment or capabilities.
Review your HDI requirements
Share the board revision, proposed stackup, quantity and open questions. Include the requirements discussed in this guide so the project review starts with the same assumptions.