Detailed Explanation of Operating Conditions for Vacuum Coating Machines

Vacuum coating technology is widely applied in various industries such as semiconductors and automotive components. It enhances product performance by depositing films in a high-vacuum environment. The vacuum coating machine, as the core equipment, requires a series of specific conditions for stable operation. These conditions directly determine the coating quality, equipment lifespan, and production safety. This article comprehensively analyzes the operating conditions from six core dimensions, providing practical references for industry practitioners.

The vacuum coating machine has strict requirements for the operating environment. Factors such as temperature, humidity and cleanliness directly affect the stability of the equipment and the quality of the coating. Establishing a standard operating environment is the prerequisite for the equipment to function properly.

Temperature stability is a crucial environmental parameter. During equipment operation, the core components generate heat, and excessively high or fluctuating temperatures can affect vacuum control and process stability. The optimal operating environment temperature is 10 to 30℃, and the core operation area is 20 to 25℃, with temperature fluctuations not exceeding ±2℃.

In actual production, the equipment should be kept away from direct sunlight and air vents of the heating system to ensure good ventilation in the machine room. The temperature can be controlled by a constant temperature air conditioner. High-power equipment needs to be equipped with a dedicated cooling device to prevent component aging and performance degradation.

High humidity can lead to a decrease in the sealing of the vacuum system, damage to the film layer quality, and corrosion of electrical components. Therefore, the relative humidity of the operating environment should be controlled below 70%, with the optimal range being 40% to 60%.

In high-humidity areas or seasons, a dehumidifier should be installed. Regularly check the dryness of the sealing rings and apply special lubricating grease; avoid opening the cabin door during rainy days or in high-humidity conditions to prevent humid air from entering the chamber.

Dust, oil stains and other impurities in the air can cause problems such as pinholes in the film layer and reduced adhesion, and even lead to product scrapping. The equipment needs to be installed in a cleanroom with a cleanliness level of over 10,000, and the core operation area must meet the standard of 10,000 cleanliness.

The computer room should be equipped with an air purification system and the filters need to be replaced regularly. The operators should wear clean protective gear. Items that may generate dust should not be piled up around the equipment. The computer room and the surfaces of the equipment should be cleaned regularly.

The core components such as molecular pumps and vacuum gauges are sensitive to vibrations. Even slight vibrations can affect the stability of the vacuum and the uniformity of the film layer. The equipment should be installed in an area with minimal vibrations. The ground should be treated for vibration prevention to avoid being placed adjacent to equipment with strong vibrations.

At the same time, strong electromagnetic interference must be avoided. The computer room should be located far away from radiation sources such as high-voltage lines. The electrical circuits of the equipment should be shielded and grounded to prevent the loss of process parameters.

The vacuum environment is the core of vacuum coating. The performance of the vacuum system and the accuracy of vacuum degree control directly determine the feasibility of coating and the quality of the coating layer. The operating conditions mainly revolve around vacuum degree, pumping rate, sealing performance, and component status.

Different coating processes have different requirements for vacuum degree, which are classified into three levels: low, medium and high. Precise control is necessary according to the process.

Low vacuum coating (such as in the early stage of evaporation coating) requires 1*10⁻¹ to 1*10⁻³ Pa, which is used to expel air and moisture; medium vacuum coating (such as in some magnetron sputtering) requires 1*10⁻³ to 1*10⁻⁵ Pa, suitable for scenarios where the purity of the coating layer is moderately required; high vacuum coating (such as electron beam evaporation) requires more than 1*10⁻⁵ Pa, used for coating of high-end products.

The vacuum level should be reasonably set based on the materials and processes. For example, in reactive magnetron sputtering, it needs to be dynamically adjusted within the range of 0.1 to 5 Pa. During equipment operation, the fluctuation of the vacuum level must not exceed 10% of the set value; otherwise, the machine needs to be shut down for troubleshooting.

The pumping rate determines the time it takes for the chamber to reach the target vacuum level and its stability. Insufficient pumping rate will prolong the production cycle and affect the quality of the film layer.

The vacuum system adopts the "coarse pumping + fine pumping" mode: The coarse pumping is handled by a mechanical pump, which needs to reduce the pressure from atmospheric pressure to 1*10⁻¹ Pa within the specified time; the fine pumping is carried out by a molecular pump, etc., and it needs to reach the set vacuum level within 30 to 60 minutes.

During operation, it is necessary to regularly check the vacuum pump's air-pumping performance and promptly identify and solve problems such as aging oil quality and blocked pipelines to ensure the normal operation of the system.

Sealing performance is the key to ensuring stable vacuum level. Leakage will result in non-compliance with the vacuum standard and affect the coating process. The sealing performance of components such as vacuum chambers and pipelines must strictly meet the standards.

Before the equipment is put into operation, its sealing performance should be tested by helium mass spectrometry leak detection method or pressure rise rate method. If the pressure rise rate exceeds 5*10⁻² Pa/min, the leakage points should be identified.

It is necessary to conduct regular inspections of the sealing rings and vacuum valves, clean the chambers and pipelines, and prevent the sealing surfaces from getting clogged.

The operating conditions of core components such as vacuum pumps and vacuum gauges directly affect the performance of the system. Therefore, the following requirements must be strictly met:

The mechanical oil pump should be replaced every 200 hours. The new oil needs to be filtered to NAS 6 grade. The molecular pump bearings need to be lubricated with grease every 5,000 hours. The grease should be replaced if the rotational resistance exceeds the limit. The vacuum gauge should be calibrated regularly, with an error of no more than ±1%. The vacuum valves should be checked for their flexibility in operation to avoid leakage or poor vacuum extraction due to faults.

Stable power supply and efficient cooling system are the guarantees for the normal operation of the equipment, which can prevent faults caused by power fluctuations and overheating, as well as the deterioration of coating quality.

The power system is divided into the main power supply and the control power supply. The main power supply supplies power to the high-power components, while the control power supply supplies power to the precision components. Both need to meet strict requirements.

The main power supply uses three-phase 380V, 50Hz alternating current, with voltage fluctuation within ±5%. The frequency is 49 to 51Hz. The control power supply uses single-phase 220V, 50Hz alternating current, with voltage fluctuation within ±3%. The equipment needs to be grounded separately, with the grounding resistance no more than 4Ω.

It is necessary to be equipped with an UPS emergency power supply to prevent equipment and products from being damaged in case of sudden power outage; for high-power equipment, a separate transformer should be configured to avoid voltage fluctuations.

During the operation of the equipment, the core components will generate a large amount of heat. Failure to dissipate the heat promptly will lead to a decline in component performance and deformation. The cooling system must meet the requirements of the equipment.

High-power equipment adopts a water cooling system, while low-power equipment uses a wind cooling system. The inlet water temperature of the water cooling system is ≤ 25℃, the outlet water temperature is ≤ 35℃, the water pressure is 0.2 to 0.4 MPa, and the flow rate is set according to the equipment power.

Daily checks should be conducted to ensure the smoothness of the cooling pipeline, remove scale from the water tank, and inspect the condition of the water pump; for the air-cooling system, the dust on the heat sinks should be cleaned regularly to ensure good heat dissipation.

The quality and specifications of the coating material, substrate and auxiliary materials directly determine the performance and appearance of the film layer, and must strictly meet the operating conditions.

The purity and form of the coating materials need to match the process and product requirements: For vacuum evaporation coating, metals or alloys with a purity of ≥ 99.99% are selected, and there are no oxidized impurities on the surface; for magnetron sputtering targets, the purity is ≥ 99.9%, and the surface is flat and the size is suitable.

The vapor pressure and melting point of the material need to be matched with the vacuum degree and evaporation power. For example, for high-melting-point materials, electron beam evaporation can be used; while for low-melting-point materials, resistance heating evaporation can be adopted.

The substrate must be compatible with the coating material, have a clean and flat surface, and be of the appropriate size. Otherwise, it will affect the adhesion and uniformity of the coating layer.

Before coating, the substrate needs to undergo "mechanical cleaning + chemical cleaning + plasma cleaning" pre-treatment. For metal substrates, they should be preheated to 150-200℃ to release internal stress, and for plastic substrates, the preheating temperature should be ≤ 80℃ to prevent deformation.

Auxiliary materials such as vacuum pump oil, sealing rings, and process gases must meet the requirements for equipment operation.

The vacuum pump oil is selected with a specific model, and the sealing ring is made of fluororubber that is resistant to high temperatures and vacuum; the purity of the process gas is ≥ 99.999%, and the flow rate is controlled by a high-precision flowmeter, with an error of ≤ ±1%.

The operation of the equipment involves dangerous factors such as high pressure, high temperature and high vacuum. It is necessary to strictly adhere to safety conditions to avoid any safety accidents.

Evaporation sources, sputtering targets, etc. require high-voltage power supply (up to 30kV). The equipment must be equipped with high-voltage alarm and grounding devices, and the high-voltage lines should be shielded. Operators should wear insulating protective gear. During maintenance, power should be disconnected and discharged first.

The core components operate at extremely high temperatures. The equipment needs to be equipped with a high-temperature protection barrier, and the operators should wear heat-resistant protective gear. Items that are flammable or explosive are prohibited from being piled up around the equipment, and fire-fighting equipment should be provided.

Opening the cabin door before the chamber is depressurized can easily cause danger. Therefore, the equipment should be equipped with a vacuum pressure alarm device. Before opening the cabin door, it is necessary to confirm that the pressure has returned to normal. During operation, the sealing performance should be checked regularly.

The equipment should be equipped with emergency stop buttons, emergency pressure relief valves and other devices. The emergency stop button should be easy to operate. The computer room should be equipped with fire extinguishing equipment, and the operators should be familiar with the emergency handling methods.

The professional competence and operational standardization of the operators directly affect the equipment operation, coating quality and safety, and must meet the corresponding requirements.

Operators should be familiar with the principles of vacuum coating, the structure of the equipment and the process flow, master the methods of parameter adjustment, and possess the ability to diagnose and handle faults; they must undergo professional training and pass the assessment before they can start working.

Operators must strictly follow the procedures: Before starting the equipment, check its condition; during operation, monitor parameters; and stop the machine immediately in case of any abnormalities; after the operation is completed, shut down the equipment as per regulations, clean it up, record the operation details and establish an archive.

Operators should have a strong sense of safety, wear protective equipment, and be familiar with emergency procedures; they should regularly participate in safety training and drills to enhance their safety operation and emergency handling capabilities.

The operating conditions of the vacuum coating machine are systematic and holistic. The six core conditions are interrelated and indispensable. Only by strictly meeting these conditions can the equipment operate stably and efficiently, and ensure the coating quality and production safety.

With the advancement of technology, the precision and complexity of equipment have increased, and the requirements for operating conditions have become more stringent. Practitioners need to enhance their professional skills, standardize operations, strengthen equipment maintenance, optimize operating conditions, and promote the wide application of vacuum coating technology.