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An analysis of the advantages of plasma cleaners in the circuit board industry: 1. Desmearing and activation with plasma cleaners: mainly used for removing contamination and resin smear from multilayer rigid boards, flexible circuit boards and rigid-flex boards; treating carbonized residue in holes after laser drilling; activating hole walls of PTFE printed boards before hole metallization; and activating board surfaces before coating. 2. Pre-coating treatment: treating printed circuit board surfaces before coating solves problems such as skip plating in surface coating, and pre-treatment before dry film lamination and surface coating can improve problems such as poor adhesion of dry film and coatings, ensuring product quality. 3. FPC circuit boards: as substrates for electronic components, printed circuit boards are electrically conductive, which makes it challenging to treat them with atmospheric-pressure processes. Any surface pre-treatment method that introduces even a small electrical potential may cause a short circuit, damaging the circuit layout and electronic devices.

The in-line plasma cleaner focuses on applications in plasma surface modification, or plasma surface treatment. It exploits the high energy and instability of plasma: when the surface of a solid material comes into contact with plasma, its microstructure, chemical properties and energy all change. Plasma surface modification (plasma surface treatment) uses these characteristics of plasma to clean, activate and excite the surface of the solid material to be treated, thereby changing its surface microstructure, chemical properties and energy. The ultraviolet cleaner, also known as a UV ozone cleaner or UV cleaning machine (smaller units are also called UV ozone cleaning instruments or UV ozone cleaning devices), is called a UV OZONE CLEANING SYSTEM in English. Photo-cleaning technology has a very wide range of applications and is currently quite common in the modern information technology industry. As China's industrial modernization progresses, photo-cleaning and photo-modification technologies will also gradually be applied in industrial production fields such as metals, plastics and rubber.

Cleaning with a plasma cleaner is one of the more common methods of plasma surface modification. (1) Etching of material surfaces by plasma cleaners: physical action Large numbers of ions, excited-state molecules, free radicals and other active particles in the plasma act on the surface of the solid sample. This not only removes the original contaminants and impurities from the surface but also produces an etching effect that roughens the sample surface and forms many fine pits, increasing the specific surface area of the sample and improving the wettability of the solid surface. (2) Plasma cleaners activate bond energy: crosslinking The energy of particles in plasma is 0~20eV, while most bond energies in polymers are 0~10eV. Therefore, when plasma acts on a solid surface, it can break the original chemical bonds on the solid surface, and free radicals in the plasma form a network crosslinked structure with these bonds, greatly activating the surface. (3) Plasma cleaners form new functional groups: chemical action If a reactive gas is introduced into the discharge gas, complex chemical reactions take place on the activated material surface, introducing new functional groups such as hydrocarbyl, amino and carboxyl groups. These functional groups are all active groups and can significantly increase the surface activity of the material.

An in-line plasma cleaner performs dry cleaning, mainly removing very fine oxides and contaminants. It uses a working gas excited into a plasma by an electromagnetic field, which reacts physically and chemically with the object surface to clean it; an ultrasonic cleaner performs wet cleaning, mainly removing obvious dust and contaminants, which is a form of rough cleaning. It cleans objects with a liquid (water or solvent) under ultrasonic vibration. In-line plasma cleaners are used for a different purpose: they mainly improve the bonding performance of the surfaces of the items being cleaned. The workpiece surface is not necessarily washed clean, but bonding performance is much better than without treatment. Ultrasonic cleaners are mainly used to clean workpiece surfaces and improve surface cleanliness.

A plasma cleaner consists of three main parts: the control unit, the vacuum chamber and the vacuum pump. Each of these three parts is described below: 1. Control unit: For plasma cleaners currently used in China, including imported ones, the control unit falls into four main types: semi-automatic control, fully automatic control, PC control and LCD touchscreen control. The control unit is in turn divided into two main parts: 1) Power supply: there are three main power supply frequencies, 40KHz, 13.56MHz and 2.45GHz. The 13.56MHz supply requires a matching network, while 2.45GHz is also called microwave plasma. Their main functions were mentioned earlier, so we will not go through them one by one here. 2) System control unit: there are three types, namely button control (semi-automatic, fully automatic), computer control and PLC control (LCD touchscreen control). 2. Vacuum chamber: Vacuum chambers come mainly in two materials: 1) stainless steel vacuum chambers, 2) quartz chambers. 3. Vacuum pump: There are two types of vacuum pumps: 1) dry pumps, 2) oil pumps

The operating process of a plasma cleaner is as follows: (1) The workpiece to be cleaned is loaded into the vacuum chamber of the plasma cleaner and fixed in place. The operating unit is started and pump-down begins, until the vacuum in the chamber reaches a standard vacuum level of about 10Pa. Pump-down generally takes about 2min. (2) The plasma cleaning gas is introduced into the vacuum chamber and its pressure is maintained at 100Pa. Depending on the material being cleaned, gases such as oxygen, hydrogen, argon or nitrogen can be selected. (3) A high-frequency voltage is applied between the electrode in the vacuum chamber and the grounding device, causing the gas to break down; the gas is ionized through glow discharge and plasma is generated. The plasma generated in the vacuum chamber fully envelops the workpiece being treated, and cleaning begins. Cleaning typically lasts from several tens of seconds to a few minutes. (4) After cleaning, the high-frequency voltage is switched off and the gas and vaporized contaminants are exhausted. At the same time, air is admitted into the vacuum chamber and the pressure is raised to one atmosphere. Plasma is generated mainly by electrons striking neutral gas atoms, dissociating them to produce plasma. However, the nucleus of a neutral gas atom binds its outer electrons with a certain energy, which we call the binding energy. An external electron must have more energy than this binding energy to be able to dissociate the neutral gas atom, but such external electrons often lack sufficient energy and cannot dissociate neutral gas atoms. Therefore, we must supply external energy to give the electrons energy so that they are able to dissociate the neutral gas atoms. A simple way to supply energy to electrons is to apply a DC voltage across parallel electrode plates. Electrons between the electrodes are attracted and accelerated by the positively charged electrode and accumulate energy as they accelerate. When an electron's energy reaches a certain level, it is able to dissociate neutral gas atoms.

The cleaning principle of the in-line plasma cleaner: Plasma is a state of matter. Matter normally exists in three states (solid, liquid and gas), but under certain special conditions a fourth state exists, such as the matter in the ionosphere of the Earth's atmosphere. The plasma state contains the following: electrons moving at high speed; neutral atoms, molecules and radicals in an excited state; ionized atoms and molecules; and unreacted molecules and atoms. Overall, however, the matter remains electrically neutral. In the vacuum chamber, an RF power supply ignites a glow discharge at a given pressure, generating high-energy, disordered plasma. The plasma bombards the surface of the product being cleaned to achieve the cleaning effect. Applications of in-line plasma cleaners: In-line plasma cleaners are typically used for: 1. Plasma surface activation/cleaning. 2. Bonding after plasma treatment. 3. Plasma etching/activation. 4. Plasma glue removal. 5. Plasma coating and plating (hydrophilic, hydrophobic). 6. Enhancing bondability. 7. Plasma coating. 8. Plasma ashing, surface modification and similar applications. This treatment improves the wettability of material surfaces, enables coating, plating and similar operations on many materials, and strengthens adhesion and bonding strength, while removing organic contaminants, oil stains or grease. In-line plasma cleaners are now widely used in electronics, telecommunications, automotive, textiles, biomedicine and other fields. Examples in electronic products include coating treatment of LCD/OLED screens; pre-bonding treatment of PC plastic frames; surface treatment of structural parts such as housings and keys before spray painting and silk-screen printing; glue and contamination removal from PCB surfaces; treatment of lenses before adhesive bonding; and treatment of wires and cables before inkjet coding. In the automotive industry: treatment of headlamp covers, brake pads and door sealing strips before bonding. In the machinery industry: fine, non-damaging cleaning of metal parts; treatment of lenses before coating; treatment of various industrial materials before joining and sealing; surface modification of three-dimensional objects… and so on.

With the continuous development of microelectronics technology, processor chips run at ever higher frequencies, offer ever more functions and have ever more pins, while chip feature sizes keep shrinking and package sizes keep changing. To improve product performance, in-line plasma cleaners are gradually becoming widespread. So what does this equipment consist of, and how does it work on a production line? In-line plasma cleaners offer low cost, ease of use, low maintenance cost and environmental friendliness. The substrate surface treatment is aimed mainly at IC packaging processes such as wire bonding and flip-chip packaging: flexible boards are automatically taken out of the magazine and plasma-cleaned to remove contamination from the material surface, with no human intervention. Since this equipment is so effective, let us take a detailed look at the process flow of the in-line plasma cleaning system: (A) 4 magazines filled with flexible boards are placed on the loading/unloading platform, and the pusher pushes the front strip out onto the loading/unloading conveyor system. (B) The loading/unloading conveyor system carries the strip, via pinch rollers and belts, onto the upper stage of the material exchange platform, where it is positioned by the strip shifting system. (C) The platform carrying the strip is moved under the plasma reaction chamber, and the system closes the vacuum chamber and pumps it down so that the strip can be plasma-cleaned. While the upper stage is at the cleaning position, the lower stage moves to the receiving position to receive the strip from the second layer. When cleaning on the upper stage is finished, the two stages swap positions: the strip on the lower stage is plasma-cleaned, while the upper stage moves to the receiving position to return its strip. (D) The shifting system moves the strip on the material exchange platform onto the loading/unloading conveyor system, which carries it back into the magazine via pinch rollers and belts, completing one cycle. The pusher mechanism then pushes out the strip in the next layer for the next cycle.

A plasma cleaner is equipment that uses plasma to treat product surfaces, achieving results that ordinary cleaning cannot. Plasma cleaning is generally enclosed cleaning; common types include vacuum, atmospheric-pressure and room-temperature. Sample surfaces are treated with plasma species such as ions, electrons, atoms, active groups, excited-state nuclides and photons to achieve cleaning, coating and other purposes. The main function of a plasma cleaner is to clean object surfaces, but its effects vary depending on the industry in which the plasma is used. Let's look at its effects in the LED industry, a common example: 1. Removes oxide layers or dirt, so that the chip and substrate bond more tightly with the encapsulant. 2. Improves the tightness of the bond between the encapsulant and the bracket, preventing defects caused by air penetration. 3. Removes contaminants from the board, helping the silver paste spread evenly and the chip attach. 4. Improves the adhesion of the welds between the wire and the chip and substrate, enhancing bond strength. To be fair, plasma cleaners also have some drawbacks in cleaning: 1. Relatively long cleaning time. 2. Relatively high power consumption (compared with traditional cleaning). 3. Relatively high price. 4. Requires supervision during cleaning.

After cleaning with a plasma cleaner, the cleaned object is already completely dry and can be sent to the next process without drying. Plasma cleaners do not use ODS harmful solvents such as trichloroethylene, and no harmful pollutants are produced after cleaning, making plasma cleaning a green cleaning method that benefits environmental protection. A plasma cleaner can penetrate tiny holes and recesses in an object to complete the cleaning task, without much concern for the shape of the object being cleaned. The entire cleaning process can be completed within a few minutes, so it is highly efficient. A characteristic of plasma cleaners is that they can treat different substrates, whatever the object being treated. Metals, semiconductors, oxides and polymer materials (such as polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyimide, polyester, epoxy resin and other polymers) can all be treated well with plasma. It is therefore particularly suitable for substrates that are not resistant to heat or solvents. It can also selectively clean the whole of a material, a local area of it, or complex structures. While cleaning and decontaminating, a plasma cleaner can also modify the surface properties of the material itself, for example by improving surface wettability and film adhesion. Plasma cleaners have high-precision control devices with very high time-control precision. Correct plasma cleaning does not create a damaged layer on the surface, ensuring surface quality. Because the process takes place in a vacuum, it does not pollute the environment and ensures that the cleaned surface is not subject to secondary contamination. Because plasma contains active particles such as electrons, ions and free radicals, it readily reacts with solid surfaces. Plasma cleaning mainly relies on the “activation” of active particles in the plasma to remove stains from the object surface. A plasma cleaner consists of a reaction chamber, a power supply and a vacuum pump set. The sample is placed in the reaction chamber, and the vacuum pump begins pumping down to a certain vacuum level. The power supply is then started to generate plasma, and gas is introduced into the reaction chamber so that the plasma in the chamber becomes a reactive plasma. The plasma reacts with the sample surface to produce volatile by-products, which are pumped out by the vacuum pump. Physical and chemical reactions between high-energy plasma particles and the material surface are used to activate, etch and decontaminate the material surface, improving various surface properties such as the friction coefficient, adhesion and hydrophilicity. The above explains the working principle of plasma cleaners. We hope you find it helpful. If you would like to learn more about plasma cleaners, you are welcome to consult our online customer service or call our service hotline (at the top right of the website). We will wholeheartedly provide you with quality service!