Tag Archives: Class 100 cleanroom wipes

Surface Cleaning in Class 100 Cleanrooms with Wipes

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Class 100 cleanrooms (ISO 14644-1 Class 5)—critical for semiconductor manufacturing, medical implant production, and microelectronics assembly—allow no more than 100 particles (≥0.5μm) per cubic foot. Surface cleanliness here is non-negotiable, as even minor contaminants can ruin high-value products. Specialized cleaning wipes—engineered for ultra-low linting, particle trapping, and residue-free performance—are indispensable for maintaining these strict standards. Below is a detailed breakdown of their applications in Class 100 surface cleaning, from equipment to workspaces.

1. Equipment Surface Cleaning: Protecting High-Precision Tools

Class 100 cleanrooms house sensitive equipment like lithography scanners, wafer handlers, and metrology tools, whose surfaces (e.g., glass optics, stainless steel chucks) demand meticulous cleaning:
  • Lithography Optics Maintenance: Pre-moistened cleaning wipes with 99.9% high-purity IPA remove oil residues and sub-micron dust from laser lenses and reticle masks. Their ultra-fine microfiber (0.1μm diameter) traps particles as small as 0.05μm without scratching anti-reflective coatings, ensuring light transmission accuracy.
  • Wafer Chuck Decontamination: Dry cleaning wipes (250–300 gsm) with static-dissipative properties (10⁶–10¹¹ Ω) eliminate oxide films and silicon dust from chuck grooves. This prevents wafer misalignment during processing, a top cause of 3nm/5nm chip defects.
  • Robot Arm Cleaning: Low-linting wipes (≤1 fiber shed per use) paired with deionized water clean transfer robot grippers, removing lubricant residues that attract dust. This maintains smooth wafer handling, reducing scratch risks.

2. Workbench and Furniture Cleaning: Controlling Cross-Contamination

Workbenches, fume hoods, and storage racks are primary particle collectors, requiring daily cleaning to prevent transfer to products:
  • Daily Surface Sanitization: Pre-moistened wipes with hydrogen peroxide (3%) disinfect workbenches without leaving residues, critical for sterile medical device cleanrooms. Their non-woven, continuous-filament structure ensures no fibers remain on surfaces post-wiping.
  • Fume Hood Interior Cleaning: Wipes resistant to harsh solvents (e.g., acetone) remove chemical splatters from hood walls. Their high absorbency (12x weight in liquid) contains spills, preventing solvent seepage into cracks where bacteria or particles hide.
  • Tool Tray Maintenance: Small 4”x4” cleaning wipes target dust in tool tray compartments, ensuring tweezers, scalpel blades, and probes remain particle-free before use on sensitive components.

3. Wall, Floor, and Fixture Cleaning: Reducing Ambient Particles

Even vertical surfaces and floors contribute to Class 100 contamination; cleaning wipes address these often-overlooked areas:
  • Wall Panel Wiping: Dry, high-density wipes (350 gsm) remove dust from smooth vinyl or stainless steel walls. Their large surface area (12”x12”) covers more ground, reducing wipe usage and minimizing particle release from frequent product changes.
  • Floor Mat Cleaning: Anti-static cleaning wipes with mild surfactants clean ESD floor mats, removing foot traffic residues without degrading their static-dissipative properties. This maintains a grounded environment for wafer transport.
  • Window and Viewport Cleaning: Lens-safe pre-moistened wipes (deionized water-based) clean cleanroom windows and equipment viewports, ensuring clear visibility without streaks that could obscure particle detection.

4. Post-Maintenance Cleaning: Restoring Class 100 Standards

After equipment repairs or part replacements, cleaning wipes are vital to re-establish cleanliness:
  • Post-Repair Surface Purification: Wipes with low extractable ions (≤10ppb) clean areas where tools or parts were replaced (e.g., sensor housings, valve controls). This removes fingerprints, metal shavings, or lubricants introduced during maintenance.
  • Crevice and Seam Cleaning: Wipes folded into narrow strips reach gaps between equipment panels or around fasteners, eliminating hidden dust that could migrate to product zones post-maintenance.
  • Validation Support: Wipes used in post-cleaning verification (paired with particle counters) help confirm surfaces meet Class 100 limits (≤100 particles ≥0.5μm/ft³), ensuring compliance with SEMI F21 and ISO 14644-1.

Key Benefits in Class 100 Environments

  • Particle Control: Wipes remove 99.9% of particles ≥0.1μm, far exceeding Class 100 requirements.
  • Residue Elimination: Solvent-compatible variants leave no ionic or organic residues, critical for semiconductor and medical applications.
  • Efficiency: Pre-moistened wipes reduce cleaning time by 40% vs. manual solvent application, minimizing cleanroom downtime.
In Class 100 cleanrooms, cleaning wipes are more than tools—they are guardians of quality, ensuring surfaces remain pristine enough to support the most demanding manufacturing and research standards.

Standard Use of Cleaning Wipes in Class 100 Cleanrooms

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Class 100 cleanrooms (equivalent to ISO 14644-1 Class 5) enforce ultra-stringent contamination control—allowing no more than 100 particles (≥0.5μm) per cubic foot of air. In environments like semiconductor wafer fabrication, medical device manufacturing, or microelectronics assembly, even a single fiber or trace residue can ruin high-value products. Cleanroom wipes (dry, lint-free variants) and cleaning wipes (pre-moistened with high-purity solutions) are critical tools here, but their effectiveness depends on strict adherence to standard operations (SOPs) that minimize particle generation, prevent cross-contamination, and ensure compliance. Below is a comprehensive breakdown of these SOPs, tailored to Class 100 cleanroom requirements.

1. Pre-Operation Preparation: Ensure Wipe and Operator Readiness

Before entering the Class 100 cleanroom, thorough preparation eliminates external contamination risks:
  • Wipe Selection & Inspection:
    • Choose wipes certified to ISO 14644-1 Class 5 (or better) with ultra-low linting (≤1 particle ≥0.1μm per wipe) and, if using pre-moistened cleaning wipes, a residue-free solution (e.g., 99.9% IPA, deionized water).
    • Inspect wipes under a Class 100-compatible light (e.g., LED task light) for tears, loose fibers, or visible contaminants. Discard any defective wipes—even minor flaws can shed particles.
  • Operator Gowning & Grounding:
    • Don cleanroom-appropriate attire (e.g., full-body bunny suit, gloves, face mask, shoe covers) following ISO 14644-3 gowning protocols to prevent operator-borne particles.
    • For anti-static needs (e.g., semiconductor cleanrooms), wear an ESD wrist strap connected to a grounded surface and anti-static gloves—this prevents static from attracting particles to wipes or surfaces.
  • Wipe Storage & Handling:
    • Store unopened wipes in sealed, cleanroom-grade packaging (e.g., foil-lined bags with zip closures) in a Class 100 storage cabinet. Never bring non-Class 100 wipe packaging into the cleanroom.
    • Open wipe dispensers only inside the cleanroom, and reseal them immediately after each use to avoid exposure to ambient air (which carries particles).

2. Standard Wiping Procedures for Class 100 Cleanrooms

The wiping technique directly impacts particle control—follow these steps for both dry cleanroom wipes and pre-moistened cleaning wipes:

A. Dry Cleanroom Wipes (for Particle Removal)

Use dry wipes first to eliminate loose dust before wet cleaning—this prevents particles from being pushed into surfaces or dissolved in cleaning solutions:
  1. Wipe Folding: Fold the dry wipe into a 4-layer pad (e.g., 4”x4” from a 8”x8” wipe). This creates a dense, low-linting surface and reduces the risk of the wipe edge fraying (a common particle source).
  2. Wiping Pattern: Wipe in a single, continuous direction (e.g., horizontal for flat surfaces like workbenches, vertical for walls) with overlapping strokes (50% overlap). Never use circular motions—these redistribute particles instead of trapping them.
  3. Pressure Control: Apply light, even pressure (≤1 psi). Excessive force compresses the wipe’s fibers, reducing particle-trapping capacity and increasing friction (which can generate static).
  4. Wipe Rotation: Rotate the wipe to a clean layer after every 2–3 strokes. Once all layers are used, discard the wipe immediately in a Class 100-compatible waste bin (sealed, anti-static, if needed).

B. Pre-Moistened Cleaning Wipes (for Residue/Oil Removal)

Use cleaning wipes only after dry particle removal, and prioritize residue-free solutions to avoid leaving contaminants:
  1. Moisture Check: Ensure the wipe is damp (not dripping). Excess liquid can pool in crevices (e.g., equipment seams) and evaporate, leaving mineral deposits or solvent residues. Blot excess moisture on a clean dry wipe if needed.
  2. Targeted Cleaning: For small surfaces (e.g., wafer chucks, optical lenses), use the edge of the folded wipe to reach tight spaces. For large areas, divide the surface into 1ft x 1ft sections and clean one section at a time to avoid missing spots.
  3. Evaporation Wait: After wiping, allow the surface to air-dry completely (10–30 seconds, depending on the solution) in the cleanroom’s filtered air. Do not use compressed air to speed drying—this can stir up particles.
  4. Post-Clean Dry Wipe: For critical surfaces (e.g., semiconductor wafers), follow the cleaning wipe with a fresh dry wipe to ensure no residue remains.

3. Post-Operation Protocols

  • Waste Disposal: Place used wipes in a sealed, labeled waste container (marked “Class 100 Cleanroom Waste”) and remove it from the cleanroom at the end of each shift. Do not leave used wipes inside—they can release trapped particles.
  • Dispenser Maintenance: Clean wipe dispensers weekly with a dry Class 100 wipe to remove dust from the opening. Replace dispensers if they show signs of wear (e.g., cracked lids) that could allow contamination.
  • Documentation: Log wipe usage (lot number, quantity, cleaning area) and any anomalies (e.g., defective wipes, particle spikes) in the cleanroom’s SOP log. This supports traceability for compliance audits (e.g., FDA, SEMI).

4. Critical Compliance Checks

  • Particle Monitoring: After cleaning, use a particle counter to verify surface particle levels (≤1 particle ≥0.5μm per cm²) and air particle counts (≤100 particles ≥0.5μm per cubic foot).
  • Residue Testing: For pre-moistened wipes, conduct monthly residue tests (e.g., ion chromatography, FTIR spectroscopy) to confirm no solvent or additive residues remain on cleaned surfaces.
By following these standard operations, cleanroom wipes and cleaning wipes consistently meet Class 100 requirements—protecting products from contamination, ensuring regulatory compliance, and maintaining the cleanroom’s integrity for high-precision manufacturing.