How does plasma cleaning work?

Plasma cleaning works by generating reactive ions and radicals that break down organic residues on a surface without physical contact.

What is the True Value of Plasma Cleaning?

Plasma cleaning delivers two key outcomes:

• Microscopic cleaning – Removes organic residues and particles invisible to the eye.

• Surface activation – Energises the substrate, creating highly reactive sites for bonding.

  
  

But while the cleaning effect is permanent, the activation is not. Research shows that plasma-induced surface energy starts to degrade within 30 minutes, especially under ambient conditions.

How Long Does Surface Activation Last?

After plasma treatment, your surface is at its peak reactivity. Oxygen radicals, argon ions, and other active species enhance bonding potential by increasing surface energy (50–70 dynes/cm). But this window closes quickly:

• Within 15 minutes: Best bond strength observed.

• After 30 minutes: Surface begins to deactivate.

• After a few hours: Most activation is lost, especially in open-air environments.

  
  

For wire bonding, delaying beyond 15 minutes can reduce bond strength by up to 40%.

Why is Immediate Bonding Critical After Plasma Treatment?

Metals and ceramics respond to plasma differently, but both gain high surface energy post-treatment. When bonding happens immediately after plasma, reactive molecules on the surface seek to stabilise by forming strong bonds—especially in metal-to-metal applications like wire bonding.

Wait too long, and those active sites decay. The result? Weaker mechanical adhesion and higher chances of delamination or non-stick-on-pad (NSOP) failures.

Can Other Cleaning Methods Replace Plasma Activation?

Wet cleaning, CO2 blasting, and laser methods can help remove macroscopic contamination. But none offer the dual action of plasma:

• Wet cleaning leaves solvent residues

• CO2 removes loose particles, not chemical films

• Laser ablation risks damaging sensitive surfaces

  
  

Only plasma brings you from 99% clean to 100% clean—and keeps the surface chemically ready.

What Are Practical Tips for Manufacturers?

• Inline plasma systems: Reduce handling time and keep surfaces active

• Nitrogen-purged cabinets: Preserve activation for 24–48 hours if immediate bonding isn’t possible

• Measure surface energy: Contact angle tools help track activation decay over time

  
  

Plasma cleaning is a two-part process: clean and activate. The cleaning is stable—but the activation isn’t. If you want stronger bonds and higher yields, the timing between plasma and bonding matters. Treat the surface and move fast.

FAQs

How quickly does plasma-induced activation decay?

Within 15 minutes, bonding is optimal; after 30 minutes, surface energy begins to degrade significantly.

Why can’t wet cleaning replace plasma treatment?

Wet cleaning doesn't chemically activate surfaces and often leaves solvent residues that interfere with bonding.

What tools help measure surface activation?

Contact angle measurement tools are commonly used to track surface energy changes over time.

What’s the benefit of nitrogen-purged storage after plasma cleaning?

It helps maintain surface activation for up to 48 hours by limiting exposure to air and moisture.