Investigating Incomplete Hole Metallization Before Copper Build-Up

An incomplete conductive layer in a drilled hole should be investigated at the relevant metallization stage, not assumed to be a final plating-thickness problem. First establish the actual process route and where the observation was made. Later copper deposition can change what the investigator sees.

Identify the metallization system

Atotech’s metallization portfolio distinguishes electroless copper and direct-plating approaches. The investigation must use the preparation, coverage criteria and control information for the selected system. A test or appearance expected from one route may not describe another.

Record the material construction, hole geometry and preceding drilling and preparation steps. Keep their lot references with the sample instead of beginning the investigation with the chemistry name alone.

Locate the concern in space and time

Ask whether the concern affects isolated holes, a panel region or a wider load. The distribution helps select follow-up samples but does not, by itself, prove a chemical, mechanical or handling cause.

Preserve material before adding more process history

Set aside identified samples under the process owner’s control. Keep them separate from normal product, particularly if an investigation requires a process interruption. Record any storage or handling between treatment and examination.

Compare the suspect material with an appropriate reference using the same examination method. A difference in lighting, section location or sample preparation can otherwise be mistaken for a difference in coverage.

Test the explanation

1. Review preceding operation records for the affected samples.
2. Check the selected metallization process’s control records.
3. Form a specific hypothesis with the process supplier.
4. Run a controlled comparison that changes the relevant factor.
5. Evaluate the completed interconnection as well as intermediate evidence.

Do not use a final continuity result as the sole explanation of an intermediate coverage concern. Establish the evidence appropriate to the suspected mechanism and the product’s acceptance requirements.

Record whether the corrective action applies to material preparation, equipment, process control or handling. That specificity makes recurrence monitoring useful and prevents every future hole issue from being assigned the same generic plating label.

For example, preserve the loading position when several panels in one load show a similar concern. Repeat the relevant configuration under the investigation plan before assigning the pattern to material chemistry. A positional association is useful evidence for a test, but it is not yet an explanation.

The desmear change guide covers an adjacent process boundary. The sample-selection guide helps retain the upstream history needed for a credible investigation.