What is Plasma Cleaning and Which Industries Use It?

Plasma cleaning is a precision surface preparation technique that removes organic contaminants at the atomic level. It works by exposing materials to a low-temperature, ionised gas known as plasma, which reacts with surface impurities to break them down and eliminate them.

This method is widely used in industries where bond strength, cleanliness, and reliability are non-negotiable—such as semiconductors, automotive electronics, and medical devices. Unlike traditional cleaning, plasma doesn’t rely on solvents, which makes it ideal for sensitive and high-spec applications.

Why Plasma Cleaning Matters

Plasma cleaning is a solvent-free process used to remove microscopic contaminants for superior bonding and coating performance. It's essential in high-precision industries like semiconductors, medical devices, and automotive electronics.

How Does Plasma Cleaning Work?

Plasma cleaning is a dry process performed in a controlled environment. It typically takes place in a vacuum chamber but can also be applied under atmospheric conditions. Here's a step-by-step breakdown:

1. Gas Introduction – A process gas (e.g. oxygen, argon, or nitrogen) is introduced into the chamber.

2. Plasma Generation – High-frequency energy (RF or microwave) energises the gas, creating a plasma field.

3. Surface Interaction – Energetic ions, radicals, and UV photons interact with the surface, breaking molecular bonds in organic contaminants.

4. Contaminant Removal – The byproducts (CO₂, H₂O) are evacuated, leaving the surface chemically clean and highly reactive.

What Are the Benefits of Plasma Cleaning?

Plasma cleaning provides a series of advantages compared to wet or mechanical methods:

• Improved Adhesion

  • Increases surface energy (often from <40 dynes/cm to >70 dynes/cm)

  • Enables chemical bonding rather than just physical adhesion

  • Suitable for bonding dissimilar materials (e.g. plastics to metals)

    
    

• Defect Reduction

  • Eliminates sub-micron organic residues invisible to the naked eye

  • Prevents delamination, lifting, and adhesive failure

  • Reduces Non-Stick-on-Pad (NSOP) defects in semiconductor wire bonding

    
    

• No Residues

  • Leaves no chemical film or particulate behind

  • No need for rinsing, drying, or neutralisation steps

    
    

• Eco-Friendly & Cost-Effective

  • Eliminates use of hazardous solvents

  • Lower long-term operational costs

  • Enables reduced gold plating thickness via improved adhesion

Which Industries Use Plasma Cleaning?

Semiconductors

• Removes oxides and hydrocarbons before wire bonding

• Improves intermetallic bond formation and electrical stability

• Key step before moulding, encapsulation, and die attach

  
  

Medical Devices

• Ensures sterility and strong adhesion for implants and diagnostics

• Promotes bonding in materials like PEEK, silicone, and titanium

• Enables primer-free overmoulding in catheter and sensor production

  
  

Automotive Electronics

• Stabilises sensor reliability by eliminating contamination

• Prepares substrates for conformal coating and overmoulding

• Supports miniaturisation with consistent high-yield production

  
  

Other Industries

• Optoelectronics – for lens coating and fibre-optic termination

• Aerospace – in avionics and harsh-environment bonding

• Printed Circuit Boards (PCBs) – for flux removal and underfill adhesion

What Types of Plasma Systems Are Available?

Batch Systems

• Load parts in trays or carriers

• Ideal for prototyping or low-volume production

• Uniform exposure but slower cycle times

  
  

Inline Systems

• Integrated into conveyor or robotic lines

• High throughput and automation-ready

• Reduces handling errors and activation decay

  
  

Low-Pressure (Vacuum) Plasma

• Highly uniform treatment across complex geometries

• Superior for ultra-clean applications

• Requires vacuum chamber and pumping systems

  
  

Atmospheric Plasma

• Operates in ambient air or with controlled gas streams

• Easier integration into existing lines

• Less uniform but faster and more scalable for flat surfaces

Plasma cleaning is not just a tool—it’s a foundational step for any manufacturer seeking reliable adhesion and contamination-free surfaces. Whether you're bonding, coating, or packaging, surface quality determines the outcome.

If this is something your process might benefit from, get in touch with a plasma cleaning expert to find out which solution is best for your application.

FAQs

How long does plasma activation last?

Typically 30 minutes to a few hours under ambient conditions. For extended longevity, use nitrogen storage.

Can plasma cleaning remove visible dirt?

No. Plasma cleans at the microscopic level and must be used after gross cleaning steps if visible dirt is present.

Is plasma safe for sensitive materials?

Yes. Process parameters (gas type, power, time) can be tuned to safely treat even delicate substrates.

What gases are used in plasma cleaning?

Common gases include oxygen, argon, nitrogen, and air. The choice depends on material and cleaning goals.

How does plasma compare to wet cleaning?

Plasma is solvent-free, residue-free, and ideal for precision parts. Wet cleaning is faster but leaves contaminants and requires disposal.