Optimize the Interconnect:
When Chemistry Gets a Seat at the Table

Manufacturing folklore has a long shelf life. Rules of thumb. Proven settings. “We’ve always done it this way.” They work—until they don’t.

In the third episode of On the Line with MKS, Optimize the Interconnect (OTI) reaches a pivotal moment. Up to now, the conversation has focused on alignment—between laser drilling, chemistry, and process thinking. In this episode, that alignment is tested under a microscope. Literally.

Roger Massey and Frank Bruning from MKS Atotech take OTI into the world of nano voids, crystallization, and surface chemistry, revealing why some vias last for decades while others fail long before anyone expects—and how predictability is finally replacing intuition.

Episode 3 of the OTI Story

Author: Ryan Wagner
Released: August 19, 2026

The Via Remembers Everything

At HDI and UHDI scales, blind microvias are unforgiving.

Every laser pulse changes copper morphology. Every chemical interaction reshapes an interface. Every thermal event leaves a record.

Roger and Frank describe a simple but uncomfortable truth: the via doesn’t forget any of this. By the time plating is complete, the interconnect already carries a full history of its formation.

OTI exists to read that history—and learn from it.

Nano‑Voids: Small Defects, Big Consequences

One of the most powerful moments in Episode 3 comes when nano‑voids are reframed—not as mysterious defects, but as classifiable, preventable phenomena.

Frank walks through years of investigation triggered by a single customer question: What are we seeing at these copper‑to‑copper interfaces, and why?

The answer turned into a taxonomy—multiple categories of nano‑voids, each with distinct causes:

  • Thermally induced interactions
  • Catalyst agglomerations
  • Plating‑related inclusions
  • Interface roughness effects
  • Process sequencing errors
  • Equipment‑driven artifacts

Once categorized, nano‑voids stopped being random failures and became engineering variables.

That’s a recurring theme in OTI.

Smooth Is Not the Enemy

One of the most disruptive insights in this episode overturns decades of conventional wisdom.

Rougher is not always better.

Historically, aggressive roughening was equated with strong adhesion. But Frank and Roger explain how excessive roughness creates microscopic “peaks” that attract plating additives unevenly. The result is non‑uniform deposition, trapped contaminants, and higher likelihood of nano‑void formation.

Under OTI, smoother target pads—created through optimized laser drilling and refined wet processing—produce more uniform chemistry response and more reliable interfaces.

It’s a fundamental shift in thinking.

Crystallization: Where Reliability Is Truly Set

Perhaps the most profound insight in Episode 3 is the discussion of copper crystallization.

Plated copper doesn’t start life as a crystal. It begins as an amorphous deposit that must later crystallize. How—and where—that crystallization front moves determines whether the via becomes a single, mechanically robust structure or a layered weak point waiting to crack.

Roger explains the difference:

  • Bottom‑up crystallization: ideal, single‑crystal continuity
  • Top‑down crystallization: interrupted diffusion, multiple crystal domains, structural weakness

The causes are no longer speculative. Interfaces contaminated by oxides, residues, or improper additive interactions physically block diffusion fronts. Crystallization responds accordingly.

For the first time, these behaviors are being engineered deliberately, not discovered accidentally.

From Qualitative Judgment to Quantitative Insight

One of the most critical outcomes of this work is the shift from visual judgment to measurable predictability.

Instead of saying “this via looks good,” MKS teams developed methods to assign numerical indicators to crystallographic quality—correlating them directly with thermal cycling and long‑term reliability.

This marks a turning point for the industry.

If reliability can be predicted from microstructural analysis, then failures no longer need to be discovered in the field—or even at final test.

They can be prevented at design time.

Why This Matters Now

This level of insight isn’t academic. It arrives at a moment when:

  • Via diameters are shrinking
  • Aspect ratios are increasing
  • Thermal loads are rising
  • UHDI architectures are becoming mainstream

In this environment, “good enough” process control is no longer good enough.

OTI, as shown in Episode 3, is about engineering certainty into microscopic structures that must perform millions of times without failure.

Chemistry as a Strategic Partner

The biggest takeaway from this episode is not a single technical insight, it’s a role change.

Chemistry is no longer a downstream necessity. It is a strategic design tool.

When chemistry and laser physics are developed together, the interconnect becomes predictable, repeatable, and resilient.

That is the heart of Optimize the Interconnect.

🎧Listen to the deep technical details

Next in the series: Redefining Via Formation (Episode 4)