Unveiling the manufacturing process of cleanroom wipes: key technologies from ultrasonic edge sealing to gamma ray sterilization

As the core consumable in the field of precision manufacturing, dust-free cloth plays an irreplaceable role in semiconductor manufacturing, biomedical laboratories and optical instrument assembly. Its unique electrostatic elimination structure and microfiber weaving process can effectively avoid secondary pollution caused by traditional cleaning materials and meet the strict requirements of clean rooms of different grades from ISO Class 5 to Class 1. On the microelectronic chip production line, dust-free cloth treated with plasma can achieve particle release amounts of less than 0.1μg per square meter, which is directly related to the improvement of wafer yield.

1. Key influence of manufacturing process on dust-free cloth performance. Modern dust-free cloth manufacturing generally adopts meltblown-spunbond composite process. Through the three-dimensional network structure formed by interlacing of nano-scale fibers, micro particles above 0.1μm can be captured. It is worth noting that advanced ultrasonic edge sealing technology can effectively control fiber shedding, which can reduce the generation of wire chips by 80% compared to traditional hot cutting processes. In the production of medical-grade dust-free cloth, enterprises will adopt gamma ray sterilization process to ensure that the product meets the bioload requirements of GMP standards.

2. The classification system and process characteristics of dust-free cloth are based on the ASTM F51 standard. Professional-grade dust-free cloth is mainly classified from two dimensions: material structure and purification grade: 1. Fiber system classification: - High-density braided type (porosity ≤5%): suitable for cutting fluid cleaning - Electrospinning microfiber type (monofilament diameter 0.01-0.1dtex): used for optical mirror cleaning - Composite meltblown structure: specializes in the adsorption of ink pollutants

3. Cleanliness classification: - Level 10 dust-free cloth (ISO Class 4): dedicated to chip lithography workshop - Level 100 dust-free cloth (ISO Class 5): standard for medical device assembly line - Level 100 dust-free cloth (ISO Class 6): suitable for LCD panel cleaning

4. Comparative analysis of performance of mainstream materials. Taking polypropylene (PP) nonwoven fabric as an example, the microporous structure formed by its meltblown process has adsorption characteristics similar to activated carbon, which is particularly suitable for removing mechanical lubricating oil stains. However, due to the hydrophobicity of the material itself, its water absorption rate usually does not exceed 200%. In contrast, the sponge wipe cloth prepared by polyurethane (PU) open-pore foaming technology can achieve 800% liquid absorption retention rate with a micropore structure of more than 500 per cubic centimeter. This characteristic makes it the first choice for chemical laboratories to treat acid and alkali solutions.

5.In the field of precision wiping, PET-PA microfiber dust-free cloth using two-component composite process is becoming a new trend in the industry. Through the composite weaving of 0.05D ultrafine denier fiber and island fiber, this type of product has both nano-level cleaning ability and excellent wear resistance. It can be reused for more than 50 times in wafer surface cleaning operations, which is 3 times the service life compared to traditional products.

Guide to selecting industrial-grade wipe materials: performance analysis and application scenarios

6. Technical characteristics of PVA sponge wipe cloth. Hard sponge made of polyvinyl alcohol foaming technology has structural strength similar to ABS engineering plastic in dry state.  When exposed to deionized water, the material porosity can be instantly increased to more than 85%, forming a three-dimensional mesh adsorption structure. This characteristic makes it excellent in scenarios such as sterile filling line cleaning and wafer factory lithography machine maintenance in the pharmaceutical industry. It is especially suitable for ultra-clean environments above ISO Class 5 (original level 1000), and can effectively remove nano-scale particles residues.

7. Analysis of the cleaning efficiency of polyester composite woven fabrics. The dense structure formed by interweaving 70% polyester and 30% nylon, with a surface friction coefficient of 0.15-0.25μ, which is particularly suitable for removing viscous residues such as UV glue and epoxy resin. However, when dealing with polishing powder or metal debris with particle size greater than 5 μm, it is recommended to use it in combination with a vacuum adsorption device to avoid the risk of secondary contamination.

8. Comprehensive performance evaluation of polyester knitted fabrics is made of elastic fabrics made of double-sided jacquard technology, and their wear resistance index reaches the level 9 of ASTM D3886 standard. In the semiconductor packaging test process, this material can effectively remove flux residues and fingerprint contamination, and volatilize 40% faster than traditional cotton cloth when used with isopropanol solvent, greatly shortening the process waiting time. However, the raw material cost is about 35% higher than that of ordinary wipes, and the selection needs to be made according to the budget.

9. Technical solution of high-clean polyester knitted fabric 100% polyester fiber has been shaped at high temperature, and the surface roughness is controlled within Ra0.8μm, which complies with the IEST-RP-CC004.3 clean room standard. During the manufacturing process of liquid crystal panels, the material can achieve a cleaning effect of ≤50 particles (particle size ≥0.3μm) per square foot. Due to the hydrophobic properties of the material, it is recommended to use hydrophilic modification treatment with surfactants to reduce its contact angle from 110° to 30°, significantly improving the liquid carrying capacity.

10. The technology of fully polyester non-woven wipes has made a breakthrough in the microfiber material made of meltblown process, with fiber diameter reaching 0.8-2μm. Compared with traditional wood pulp composite non-woven fabrics, the particle release amount is reduced by 80%. In the sterilization and packaging process of medical devices, this product has passed ISO 14644-1 certification and is suitable for medical-grade clean room environments. However, it is necessary to note that its liquid retention ability is weak, and it is recommended to use a pre-wetting process to improve the use efficiency.

11. Application limitations of wood pulp non-woven fabrics indicate that natural cellulose fibers are formed by hydrospinning process, and their porous structures can withstand up to 300 wipe cycles. In the automotive spraying workshop, the oily masking glue residue can be effectively removed, but the fiber shedding amount reaches 200-300 particles per square meter, and it is only recommended to be used in clean environments below 10,000.

Guidelines for selecting industrial-grade wipe materials and analysis of technical parameters Performance analysis of composite fiber non-woven wipes. Wood pulp/viscope and polyester composite non-woven structural wipes form an efficient physical adsorption mechanism through a three-dimensional interlaced fiber network. Its unique non-woven structure shows excellent macro pollution removal capabilities, and is especially suitable for preliminary cleaning of heavy oil pollution scenarios such as automobile manufacturing and mechanical processing. It is worth noting that this material showed that the cleanliness level can only reach Class 8 (0) in the ISO 14644-1 standard test.  5μm particles are >3,520,000/m³), and the fiber shedding rate after soaking with IPA solvent is as high as 0.12%, so it is not recommended to be used in clean environments such as semiconductors or biopharmaceuticals.

Applicable scenes of cotton woven wipes. With the natural cellulose fiber structure, cotton woven knit wipes can still maintain more than 90% mechanical strength under a high temperature environment of 150℃. They are particularly suitable for water-based additive wipes in hot pressing process. Laboratory data shows that its removal efficiency of water-based stains is 82%, but due to the natural fluff properties of cotton fibers, fiber shedding of about 1,200 pieces/㎡ will occur in dynamic friction tests, so the cleanliness can only meet the dust-free environment requirements below Class 7 (ISO standard).

Technical specifications for cleaning rooms special wipe materials are professional-grade dust-free cloth prepared by ultrafine polyester fibers through meltblown process. The diameter of the single filament is controlled within the range of 0.8-1.2μm, and the surface is plasma treated to form a microporous structure. This special construction allows the material to exhibit a 99.6% particle retention rate in the VDA 19.1 standard test, which is particularly suitable for the treatment of suspended particles below 5 μm. Key performance indicators include: ion release amount<0.1 μg/cm², non-volatile residue <3ppm, and LPC test value <25CFU/100cm².

The six core application scenario technologies are adapted to the semiconductor wafer cleaning process. The production of 12-inch silicon wafers requires the use of Class 1 dust-free cloth, and its surface resistance must be controlled within the range of 10^6-10^9Ω/sq. The head assembly process requires that the wipe material have a particle retention capacity of 0.03μm, which is directly related to the technical specifications of the flight altitude of the hard drive. In the field of medical equipment manufacturing, orthopedic implant cleaning requires sterilization-grade dust-free cloth that meets ISO 13485 standards, and its biological load must be<10CFU/g.

When establishing scientific cleaning procedures for the technical process formulated by the cleaning plan, it is recommended to adopt the pollution analysis method of VDA 19.2 standard. First, the contaminant components are identified through FT-IR spectroscopy. For example, silicone oil-based lubricants need to use a low-surface tension wipe. For optical lens cleaning, an electrostatic dissipation type dust-free cloth should be selected, and its friction voltage should be<100V.

In the field of industrial cleaning, professional material selection requires systematic consideration of multiple technical parameters. Operators should give priority to assessing the three physical characteristics of the cleaned object: surface temperature tolerance range, material hardness index, and scratch resistance requirements. For precision instrument cleaning, it is recommended to use ISO 14644 standard for cleanliness grading verification, and the surface silicone residue concentration and metal ion pollution level need to be detected. Typical application scenarios include semiconductor wafer cleaning and medical device disinfection.

Organic solvent compatibility evaluation is the core link in material selection. Since commercially available dust-free cloths mainly use polyester fiber or cellulose-based polymer materials, the matching degree of its solubility parameters (HSP values) with the cleaning solvent directly determines the safety of use. Industrial alcohol (HSP=22.        3 MPa^½) As an example, if the difference between the solubility parameter of the wipe material is less than 3 units, a dissolution effect similar to "sugar dissolved in water". Laboratory data show that the HSP value of high-quality polypropylene dust-free cloth is usually maintained in the range of 18-20 MPa^½, which can effectively resist the penetration and erosion of common solvents.

Based on the principles of materials engineering, we have compiled five major selection guides:

For high-temperature surface treatment (above 80℃), pure cotton or wood pulp spunlace nonwovens should be used. This type of material exhibits a shrinkage of less than 0.5% in the thermal stability test of 180℃. 2. For silicone sensitive processes, polyester/nylon composite fabrics are recommended. The surface modification technology can control the silicone oil residue to within 5μg/cm². 3. For large-particle pollutants, knitted structures with a pore diameter of 20-50μm, and its three-dimensional fiber network is like a micro filter, with an efficiency of 92% for dust retention of more than 50μm. 4. For grease cleaning, 0.1 denier microfiber is the first choice for grease cleaning. The diameter of its single filament is only 1/100 of the human body. It can absorb 300% of its own weight through capillary effect. 5. It is recommended to use plain weave woven fabrics. The grid structure formed by its warp and weft yarns can generate mechanical shear force of 35N/cm².

It is worth noting that when processing optical parts, laser edge-sealing wipe materials should be selected, and the dust release of edges can be reduced by 80% compared to ordinary cutting products. For the biopharmaceutical industry, it is necessary to verify whether the endotoxin content of the materials meets the USP

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