FAQ of Photovoltaic Clean room & Lithium Battery Clean room

Photovoltaic Clean room and Lithium Battery Clean room 

1.How are pressure differentials and airflow designed in different rooms of photovoltaic industry clean room?
  Differential pressure control of clean rooms in the photovoltaic industry is crucial to prevent pollution and cross-contamination. Under normal circumstances, the clean area should maintain a certain positive pressure relative to the surrounding ordinary environment to prevent external pollution from entering the clean area. The pressure difference between the clean area and the non-clean area is not less than 10Pa, and the appropriate pressure difference gradient between different class of clean rooms is recommended to be 10Pa. The pressure of the high cleanliness area should be higher than that of the low cleanliness area, which can effectively prevent pollution.
  The clean room purification and ventilation system of photovoltaic industry should have a reasonable air flow organization design. ISO4-5 workshop (lithography, diffusion and other processes) should be designed according to the laminar air supply, and the other ISO6-7 workshop (cleaning, encapsulation and testing process) should adopt non-laminar air supply, and generally follow the air flow model of the upper side supplr and the lower side return. Reasonable air flow organization can prevent cross-contamination and effectively ensure the cleanliness of the workshop. If a product process or specific area has high requirements for cleanliness, laminar air supply can be used locally, that is, mixed flow organization (workshop environment turbulence, local station laminar flow), which can not only meet the requirements of product quality and process cleanliness, but also avoid the overall workshop laminar flow to reduce the cost.

2.What are the characteristics of clean room materials in the photovoltaic industry?
  The decorative materials of photovoltaic industry clean room should meet several basic requirements: 1. no dust generation and dust accumulation: the wall and ceiling surface should be smooth without pores, no dust production, easy to clean (such as color coated plate, stainless steel plate, etc.); 2, chemical corrosion resistance: need to withstand acid and alkali detergent, etching liquid and other corrosive substances (such as diffusion, cleaning area), priority to corrosion resistant coating steel plate or PVC coated material; 3. antistatic: photovoltaic industry products are very sensitive to static electricity, so the material needs to have anti-static function. This usually includes the use of anti-static floor, anti-static work clothes and gloves, as well as the installation of electrostatic remover equipment, to reduce static interference; 4. fire retardant: the decorative materials of photovoltaic industry clean room should meet the requirements of fire fire performance (such as the use of rock wool, glass magnesium color steel plate, fire resistance limit 1 hour, etc.).

3.Can key areas of photovoltaic industry clean room be built first, with expansion later?
  Different process areas of photovoltaic clean room (such as diffusion, lithography, encapsulation detection) have different cleanliness requirements (ISO 5-7). Key areas can be independently constructed and configured with its own environmental control system (such as cleanliness, differential pressure gradient, temperature and humidity regulation), other areas can be subsequently expanded by temporary isolation barrier during construction, using negative pressure dust removal equipment to prevent cross pollution. In addition, the photovoltaic clean room can also be constructed with fast installation modular clean room technology, and the core areas (such as diffusion, lithography and other high clean areas) can be constructed first. In the future, other areas (such as cleaning and encapsulation areas) can be flexibly expanded according to the production needs, and the modules are seamlessly connected through standardized interface.
  The construction of key areas first following with expansion can also reduce the initial investment, give priority to the production of key equipment, shorten the return cycle, achieve flexible expansion while ensuring the continuity of production, in line with the industry norms to reduce costs and increase efficiency needs.

4.What industry standards should the photovoltaic industry clean room comply with?
  Photovoltaic industry clean room must first comply with the ISO14644-1 international standard for clean room and associated controlled environments. This standard specifies detailed requirements for cleanliness classification, temperature and humidity control, pressure differentials, airflow organization, noise, anti-static measures, and lighting systems in photovoltaic clean room. Additionally, photovoltaic clean room should also adhere to the international electrical and electronic standards established and published by the International Electrotechnical Commission (IEC).

5.How is airtightness maintained in photovoltaic industry clean room? Are airlocks necessary?
  The key measures to maintain air tightness of clean rooms in the photovoltaic industry include reasonable structural design, efficient ventilation system, strict differential pressure difference control and the use of air brake chamber.
  Reasonable structural design: wall and roof use color steel plate or stainless steel plate and other integrated materials, combined with special aluminum profile and neutral silicone sealant treatment joints, to eliminate the risk of pore penetration; doors and windows use special clean room door with seals, and reduce the opening area and time as far as possible when opening.
  Efficient ventilation system: Reasonable ventilation system design is essential to maintain the positive pressure state inside the workshop. By adjusting the proportion of air supply and exhaust volume, dirty air can be prevented from entering the workshop to a certain extent.
  Strict differential pressure control: untreated air inflow can be prevented by establishing appropriate positive pressure differences between inside and outside the workshop. In general, the higher the cleanliness requirement, the greater the pressure relative to the external environment. The pressure difference is usually maintained between 5 and 10Pa to ensure that air flows only from clean areas to non-clean areas.
  Airlocks Room: Airlocks is one of the important measures to maintain the air tightness of clean room. The airlocks is usually located at the material entrance and the clean workshop production area directly leading to the outdoor. Through the design of the airlocks and the double door, two sealed defense lines are formed to effectively prevent the invasion of outdoor air.
  The airlocks play an important role in maintaining the air tightness of the clean room in the photovoltaic industry, so it is necessary to set the airlocks.

6.What cleanliness of clean room is required for the lithium battery industry?
  Different production stages of the lithium battery industry have different requirements for the clean room cleanliness, and the main requirements are the clean room cleanliness between ISO 5 and ISO 8.

7.How are explosion risks prevented during filling and sealing?
The main explosion prevention measures in the filling injection process are:
1. Accurate control of filling injection parameters:
â–¶Use a closed-loop control system to control the injection speed to avoid electrolyte splashing or bubble accumulation;
â–¶Through the high precision metering pump (precision±0.5%) to achieve≤1% deviation, to prevent excessive injection caused by the internal pressure abnormality;
â–¶Vacuum assistance: filling under vacuum degree≤90 kPa to eliminate the risk of bubble formation
2. Electrolyte and environmental management:
â–¶Electrolyte purity: use a high purity electrolyte with moisture content of 10ppm and metal impurity of 1ppm to avoid side reactions caused by impurities
â–¶Temperature and humidity control: the filling injection area maintains an ultra-low wet environment (dew point≤-45℃), and suppresses the decomposition of electrolyte moisture absorption.
3.Equipment protection and sealing:
â–¶Design of liquid injection needle: use double sealing needle (inner fluorine rubber + outer metal) to prevent electrolyte leakage
â–¶Nitrogen protection: ≥99.999% nitrogen into the injection station to isolate oxygen and electrolyte contact

The explosion-proof control measures in the encapsulation process are mainly:
1.Strengthen the sealing process
â–¶Laser welding: adopt the laser welding process with a pulse width of ≤0.1ms to ensure the air tightness of the shell weld (leakage rate 0.01Pa · m³/s)
â–¶Sealant selection: use electrolyte corrosion resistant silicone sealant, shear strength of 3MPa after curing
2. Anti-static electricity and mechanical protection
â–¶Electrostatic elimination: the encapsulation zone is equipped with ion air rod (≥99% neutralization efficiency) with ≤1Ω ground resistance
â–¶Anti-collision design: Soft TPU tray for cell transfer, 1.2m height without damage
3. Leak and defect detection
â–¶Leak detection by helium mass spectrum: 100% leakage detection of the packaged cells, with a detection sensitivity of ≤5x10-7Pa · m3/ s
â–¶X-Ray imaging: detect the electrode sheet alignment (deviation ≤0.1mm) and diaphragm integrity to eliminate the hidden danger of micro-short circuit
At the same time, make sure there is proper environmental interlocking, alarm control and personnel operation specifications, to avoid the risk of explosion.

7.How is flexible equipment layout achieved in lithium battery clean room to adapt to production processes?
The plane layout of the lithium battery clean room is mainly considered from several aspects:
1. Functional zoning and moving line planning
  Process oriented area division: raw material pretreatment area, electrode manufacturing area (coating / roller), core assembly area (winding / lamination), liquid injection encapsulation area and detection encapsulation area according to the production process, and buffer room (pressure difference gradient ≥5Pa) is set between each area to achieve physical isolation;
  Modular equipment layout: core equipment (coating machine, winding machine) is placed in the center, with ≥1.5m ring channel reserved for maintenance; high-precision equipment (laser welding machine) is separately equipped with shock-proof platform, ≥3m apart from ordinary equipment.
2. Flexible expansion and compatible design
  Space for expansion: reserve 15% -20% vacant areas at the edge of the equipment cluster for new equipment or process upgrades;
  Universal interface configuration: The equipment base adopts standard ground rail system (spacing error ≤ ±2mm) to support quick positioning and disassembly; compressed air / cooling water process pipeline and shunt valve to realize multi-point access.
3. Human-computer interaction optimization
  Complex moving line design: three-dimensional separation of personnel channel and material channel: personnel walk clean corridor, and materials are transported through AGV
  Intelligent logistics system: the hybrid flow system of suspended EMS track + ground AGV is introduced, and the key transport nodes are configured with visual positioning system.
  Through the above measures, while ensuring the continuity of the production process, the flexible adjustment and upgrade of the layout of the lithium battery clean room equipment are realized.

8.How long does it take to design and deliver modular clean room for photovoltaic and lithium battery industries?
  For photovoltaic and lithium battery industry, preliminary demand confirmation and scheme design require about 7-10 days according to the size of the clean room; factory material production and preparation (modular module prefabrication) require about 15-20 days; for the site assembly, only 2-3 days for small module clean room, 7-10 days for medium clean room and about 15 days for large clean room. Therefore, the module clean room project takes about 25-45 days from design to final delivery.

9.Can modular clean room be quickly installed, with zero pollution, and reduce the impact on production?
  Fast assembly module clean room is prefabricated in the factory (wall panels, roof, installation frame, efficient filter, pipe). At the construction site, only simple connection is needed, no cutting, welding dust process, no pollution to the site environment, fast installation, not affecting the normal operation of surrounding equipment, greatly reducing the impact on normal production.

10.Is there a remote monitoring and intelligent management system for the photovoltaic and lithium battery modular clean room?
  The photovoltaic and lithium battery industry is equipped with intelligent central control system, which realizes equipment interconnection through the industrial Internet of Things protocol, so as to realize remote monitoring and intelligent management:
1.Remote monitoring of environmental parameters: it can monitor the temperature, humidity, differential pressure, particulate matter concentration and other parameters of the clean room in real time, and display dynamic data through the visual interface, and support historical record query and trend analysis;

2.Intelligent management of equipment status: centralized group control of air conditioning unit, FFU (fan filter unit), lighting system and other equipment, unified / partition / separate start and stop, speed regulation, fault display alarm and energy consumption management statistics (support remote operation);

3. Collaborative control of production process: air conditioning and ventilation equipment in clean room can be linked with large devices such as coating machine and cutting equipment to automatically adjust environmental parameters according to process requirements; FFU in important areas can be linked with equipment to maintain stable cleanliness and ensure product quality.