We often refer to these microscopic particles as "Yield Killers." But to be honest, the weapons we've used against this killer for so many years have been rather primitive.
Tacky rollers? They're contact-based, prone to secondary contamination, and can scratch increasingly delicate substrates.
Ionizing blowers? They just blow particles around without actually removing them—offering little more than psychological comfort.
Manual wiping? Beyond the inefficiency, human unpredictability itself becomes the biggest source of contamination.
Leading lithium battery and display panel manufacturers have already begun adopting a dry, non-contact cleaning solution: USC dry ultrasonic cleaning. Many people seeing USC equipment for the first time might mistake it for a glorified "vacuum cleaner." However, its core principle isn't simply "suction," but rather a strategy of "first lift, then capture." It achieves over 99% removal efficiency for micron-sized particles, all without physical contact. In this opening article, I want to explore what USC truly is.
I. How Does USC Actually Work?
Step One: Neutralization—Eliminating Static
About 90% of the reason dust clings to material surfaces is static electricity. Therefore, the first thing USC does is use an ionizing bar to neutralize the static charge on the material surface.
Step Two: Agitation—Ultrasonic Vibration
The equipment blows a stream of high-pressure air. This airflow passes through a specialized ultrasonic generator, transforming into high-frequency vibrating "ultrasonic airflow." Crucially, the frequency is so high that the air doesn't just sweep across the surface. Instead, it acts like a tiny hammer, pounding the material surface at high frequency to forcibly dislodge particles that were still "holding on"—lifting and rolling them away from the surface.
Step Three: Collection—Vacuum Capture
In the instant the particles are dislodged from the surface (within just a few milliseconds), powerful negative pressure generated by vacuum chambers on either side of the cleaning head immediately draws the suspended particles away and sends them into a collection filter.
Throughout this entire process, no brushes or rollers touch the material surface. For those still using contact-based cleaning methods and worried about coating scratches, this is a particularly compelling advantage.
II. How Small Can It Remove?
Particle Size: For dry particles sized 1 micron (μm) and above, the removal efficiency consistently reaches 97% - 99%.
Process: Non-contact, with a typical operating gap of 1-2 mm, making it highly suitable for ultra-thin films and flexible materials.
Cleanliness Maintenance: Because it's a closed-loop negative pressure system, particles are immediately drawn into the filter upon removal. This prevents them from becoming airborne again and causing secondary contamination within the cleanroom.
Compare this with traditional methods: Using an air gun might remove larger particles, but smaller ones can be blown deeper into the material or surface texture. Using a lint-free wiper might remove large particles, but small ones often remain, and the friction can generate static electricity, potentially making the surface dirtier. For process nodes with extremely low tolerance for particulate contamination, USC has become the preferred, and often only, viable solution.
III. Which Production Lines Are Already Using It as a "Gatekeeper"?
Currently, USC dry cleaning's main application areas are concentrated in three sectors. These sectors share clear characteristics: expensive substrates, high yield sensitivity, and an uncompromising demand for zero surface defects.
Lithium Battery Industry (Especially Electrode Processes)
What is the biggest fear on a lithium battery production line? Metallic debris on the current collector foil before coating. If such debris gets pressed into the electrode during calendering, it can cause anything from micro-short circuits to catastrophic thermal runaway. Therefore, at critical nodes—after calendering, after slitting, and before winding—a growing number of leading companies are implementing USC. Particularly in the slitting process, where the high-speed operation of slitter blades generates significant dust and particles, USC is strategically placed between the slitter and the winder to remove this contamination.Optoelectronic Displays (Lamination and Coating)
Whether it's screen printing on smartphone cover glass or laminating polarizer films, a single particle trapped in the middle spells a rejected product. Traditional tacky rollers have speed limitations and risk leaving adhesive residue on the glass. Today, many large-area display production lines have adopted USC as the final quality checkpoint before critical processes like coating or lamination.Semiconductor-Related & Precision Coating
This includes applications like covering film lamination for FPCs (Flexible Printed Circuits), coating for photovoltaic cells, and even printing for medical packaging materials. Essentially, wherever a "surface treatment" step precedes a critical process, USC is increasingly being deployed.
Closing Thoughts
If you're struggling with micro-particle defects on your production line or evaluating new cleaning solutions, feel free to follow this series. You can also leave a comment describing your specific process conditions—let's explore together whether USC might be the right solution for you.
