As the core infrastructure of precision experiments, the design specifications and performance indicators of the cleanroom test bench must strictly follow the dual standards of scientificity and engineering. The following in-depth analysis is conducted from four dimensions: structure, materials, environmental control, and performance verification:
1、 Structural Design Specification
Modular and Load bearing Design
The test bench should adopt a steel wood or all steel structure frame, and the main frame should be made of 40mm × 60mm square steel (wall thickness ≥ 2mm), connected by hidden fastening screws to ensure a load-bearing capacity of ≥ 280kg. The tabletop should be designed with a double-layer thick edge structure (visual thickness 26mm), rounded corners to avoid stress concentration. For example, the black VIA solid core physical and chemical board tabletop can withstand strong acid and alkali corrosion.
Vibration isolation system
For vibration sensitive equipment such as atomic force microscopy (AFM), the test bench needs to integrate an active isolation base with a natural frequency of ≤ 5Hz and a load-bearing redundancy designed at 1.2 times the weight of the equipment. A 50-100mm isolation joint should be reserved between the foundation and the building floor, filled with elastic material to cut off low-frequency vibration transmission.
2、 Materials and Surface Treatment
Corrosion resistance and ease of cleaning
The countertop material must meet the ISO20307:2017 standard, using epoxy resin or acid alkali resistant board, with a surface roughness Ra ≤ 0.8 μ m to reduce particle adsorption. Steel structural components need to be pickled and phosphated before being sprayed with epoxy resin powder, with a thickness of ≥ 80 μ m, to ensure that there are no defects such as coating peeling or bubbling.
Sealing and anti-static design
All splicing gaps need to be sealed with silicone to prevent air leakage and damage to cleanliness. Anti static PVC (resistivity ≥ 18M Ω· cm) is selected for the ground, and an independent grounding electrode (resistance<1 Ω) is used to eliminate electromagnetic interference.
3、 Core indicators of environmental control
air cleanliness
The working area of the test bench must meet the ISO5 (Class 100) standard, with a dust particle count of ≥ 0.5 μ m ≤ 3520 particles/m ³ and a particle count of ≥ 5 μ m ≤ 29 particles/m ³. Adopting FFU (fan filtration unit) full coverage, combined with ULPA filter (filtration efficiency ≥ 99.9995%) to achieve unidirectional flow purification.
Temperature, humidity, and pressure difference control
Precision air conditioners need to achieve temperature control accuracy of ± 0.5 ℃ and humidity control of ± 5% RH. In scenarios such as semiconductor lithography, a rotary dehumidifier (humidity ≤ 10% RH) is required. The pressure difference between the clean room and the outside is greater than 10Pa, and the pressure difference between different cleanliness levels is greater than 5Pa, which is automatically adjusted through a residual pressure valve.
4、 Performance verification and standard basis
Testing Standard
According to JG/T292-2010 "Clean Workbench" and YY/T1539-2017 "Medical Clean Workbench", scanning leak detection, wind speed uniformity (0.3-0.6m/s), noise (≤ 65dB), illumination (≥ 300lx), and vibration amplitude (AFM equipment ≤ 50nm) need to be tested.
Long term stability verification
Continuously operate for 72 hours, monitor the temperature and humidity fluctuation range, cleanliness attenuation rate, and vibration value changes to ensure compliance with design specifications. For example, under full load operation, the number of 0.5 μ m particles on a certain brand test bench only increased by 3.2% within 72 hours, far below the standard limit.
5、 Application scenario adaptability
In the semiconductor field, it is necessary to configure an air floating platform (natural frequency<3Hz) and an ultrapure water system (resistivity ≥ 18M Ω· cm) to meet the strict requirements of photolithography processes for vibration and particles.
In the field of biomedicine, integrated ultraviolet sterilization lamps (wavelength 254nm, radiation intensity ≥ 90 μ W/cm ²) and sedimentation bacteria detection systems are used to ensure a sterile operating environment.
In the field of materials science, high-temperature countertops (temperature resistance ≥ 300 ℃) and corrosion-resistant gas pipelines (PVDF material) are used to adapt to experimental conditions.
The design of the cleanroom test bench is a systematic engineering of "structure material environment control", which requires optimizing the vibration transmission path through finite element analysis, combined with particle counters, vibration meters and other equipment for real-time monitoring, ultimately achieving a balance between cleanliness, stability and functionality.