What is Plasma Treatment?
Plasma treatment uses a controlled vacuum plasma to alter the surface of a material in order to improve bonding, printing, painting, coating, or wettability. The process is performed in a plasma chamber, under vacuum pressure, and commonly used in the manufacturing of electronic devices, medical devices, textiles, plastics, rubbers, and more. Almost any material can be treated in a plasma chamber.
Organic surface contaminants are invisible to the casual observer, but they greatly impact an object’s ability to interact with other materials.
When we plasma treat a surface, we are able to remove these contaminants. This increases the bond strength of a solder or glue, increases or decreases wettability, and ensures any type of printing, painting, or coating remains on the object's surface.
Treatments even work on shiny plastics and rubbers which are especially prone to poor adhesion due to their glossy texture.
What is plasma?
Plasma can be described as “the fourth state of matter” because it is not a liquid, a solid, or a gas. Plasma exists in the form of ions and electrons. It is essentially an ionized gas that has been electrified with extra electrons in both negative and positive states.
Although plasma is abundant elsewhere in the universe, natural occurrences are relatively rare here on Earth. Lightning, static electricity, and auroras are the main sources of natural plasma on Earth.
How is vacuum plasma treatment performed?
To plasma treat a product, first we create the plasma. A gas or mixture of gases are introduced inside a sealed, low-pressure vacuum plasma chamber. These gases are then energized by RF (radio frequency) power that has been generated between an array of electrodes. The activated ions in these gases are accelerated and start to vibrate. This vibration “scrubs” surfaces in the chamber clean of contaminants.
During this process, UV light is emitted by the excited gas molecules and atoms in the plasma. This is what causes plasma to "glow".
Temperature control systems are often used to control the etch rate. Temperatures between 60 and 90 degrees Celsius can etch up to four times faster than ambient temperature plasma. For parts that are temperature sensitive or use temperature sensitive components, plasma etching can occur down to fifteen degrees Celsius.
All of our temperature control systems are pre-programmed and integrated into the plasma system's software. Settings are saved with each plasma recipe for effortless replication of your process.
Modifications to the process can be made by introducing different gases to the chamber. Commonly used gases include O2, N2, Ar, H2, and CF4. These five gases used singularly or in combination are used in the majority of the labs around the world for plasma processing.
Treatment generally takes about two to ten minutes. When the process is complete, a vacuum pump removes the contaminants from the chamber. The materials inside the chamber are left clean, sanitized, and ready for bonding or further processing.
Plasma ashing is how carbon is removed from products during cleaning or manufacturing processes. Oxygen is used in a high frequency plasma cleaner to ensure that 100 percent of the organic material is removed by the plasma.
All removed contaminants are pumped out of the chamber by the vacuum system. The goal of plasma ashing is to completely remove organic matter, including water vapor and volatile carbon oxides.
Oxygen plasma removes 100% of organic matter and leaves no residues on the sample. If there were inorganic contaminants on the sample before treatment, they will still be present on the sample.
Plasma ashing is always performed with oxygen (O2) gas.
Who uses plasma on a daily basis?
Many universities use plasma systems for educational opportunities and lab work. They are also used by medical facilities and research labs working on new medical procedures.
Manufacturing facilities use plasma treatment to fully clean their products before bonding or printing. For example, a facility producing medical catheters will most likely use vacuum plasma technology to clean the catheter and the hose before they are bonded together. This strengthens the bond and ensures a durable, high quality product.
When manufacturing small integrated circuit (IC) chips, plasma etching is used to etch away a layer of material only a few atoms thick. Nano IC chips are now being manufactured with as little as 10nm between transistors. This calls for a very precise and uniform manufacturing process. By using a photoresist to block the etching process in the desired pattern, a few atoms of material are etched away only on the plastic where the photoresist is absent. This allows any pattern to be meticulously put down with minimal to no errors.
Next: Plasma Cleaning