1. Select Pre-Wet Wipes Optimized for Class 100 Absorption Needs

• Prioritize Hydrophilic, High-Density Fibers:
  • Opt for pre-wet wipes made from hydrophilic polyester-microfiber blends (250–300 gsm). These fibers have polar molecular structures that attract liquids (e.g., water, IPA) and a dense weave (100+ threads per inch) that traps 30–40% more liquid than standard 150 gsm wipes. Look for wipes with “high-capacity” certifications (e.g., absorbs ≥12x its weight in liquid) to ensure they handle Class 100 spills in one pass.
• Choose Solvent-Specific Formulations:
  • For aqueous liquids (e.g., deionized water for optic cleaning), select pre-wet wipes with deionized water-based solutions—they avoid residue that could contaminate wafers. For organic solvents (e.g., IPA for flux removal), use wipes pre-impregnated with 99.9% electronic-grade IPA (low impurities ≤10 ppb) to ensure compatibility with semiconductor materials and maximize absorption of solvent-based residues.
• Avoid Over-Coated Wipes:
  • Skip pre-wet wipes with excessive anti-static or preservative coatings—these clog fiber pores and reduce liquid absorption by 20–25%. Opt for “breathable” anti-static wipes (surface resistance: 10⁶–10¹⁰ Ω) with thin, porous coatings that preserve absorption while meeting ESD requirements.

2. Pre-Use Preparation to Prime Wipes for Maximum Absorption

• Ensure Proper Wipe Moisture Balance:
  • Class 100 cleanrooms often store pre-wet wipes in sealed, nitrogen-flushed containers to prevent solvent evaporation. Before use, check that wipes are uniformly damp (not dry or dripping)—dry wipes lose 50% of absorption capacity, while dripping wipes waste liquid and risk contamination. If wipes are dry, lightly mist them with the matching solvent (e.g., IPA) using a cleanroom-approved spray bottle (1–2 sprays per wipe) to reactivate capillary action.
• Fold Wipes to Maximize Absorbent Surface Area:
  • Fold pre-wet wipes into a 4-layer pad (e.g., fold an 8”x8” wipe twice to create a 4”x4” pad). This exposes 8x more fiber surfaces to liquid than using a wipe flat, accelerating absorption and extending the wipe’s usable life. For narrow areas (e.g., wafer chuck grooves), fold into a 1cm-wide strip to target liquid without over-wiping.
• Pre-Cool Wipes for Volatile Solvents:
  • For highly volatile solvents (e.g., acetone used in photoresist removal), pre-cool pre-wet wipes in a cleanroom refrigerator (4–8°C) for 10 minutes before use. Cooler wipes slow solvent evaporation, giving fibers more time to absorb liquid—this boosts absorption efficiency by 20% and reduces the need for multiple wipe changes.

3. Application Techniques to Enhance Liquid Trapping & Retention

• Apply Gentle, Even Pressure:
  • Use light pressure (<0.5 psi) when wiping—firm pressure compresses fiber pores, reducing absorption capacity by 15%. For flat surfaces (e.g., cleanroom workbenches), glide the wipe in slow, overlapping strokes (horizontal or vertical) to let capillary action draw liquid into the fibers. For vertical surfaces (e.g., equipment walls), hold the wipe against the liquid for 2–3 seconds to allow absorption before wiping downward—prevents liquid from running off the wipe.
• Use “Liquid-Directing” Strokes for Contained Spills:
  • For small, contained spills (e.g., 5mL IPA leak on a wafer cassette), wipe in strokes that direct liquid toward the center of the wipe. This concentrates liquid in the wipe’s core, preventing it from seeping out the edges and contaminating surrounding surfaces. Avoid circular motions—they spread liquid and reduce absorption efficiency.
• Layer Wipes for Large Spills:
  • For spills >10mL (e.g., broken reagent bottle), place a folded pre-wet wipe directly on the spill and top it with a second dry high-density wipe. The pre-wet wipe dissolves any solid residues (e.g., crystallized photoresist) and draws liquid upward, while the dry wipe absorbs excess moisture—this “stacked” method doubles absorption capacity and cuts cleanup time by 50%, critical for minimizing production delays in Class 100 environments.

4. Post-Use Practices to Maintain Wipe Efficacy (For Reusable Variants)

• Clean with Low-Impurity Detergents:
  • Wash wipes with lab-grade, non-ionic detergents (low impurities ≤5 ppb) to avoid residue buildup. Use cold water (≤30°C) and a cleanroom-approved washer—hot water damages hydrophilic fibers and reduces absorption.
• Air-Dry in a Controlled Environment:
  • Hang wipes to air-dry in a Class 100 laminar flow hood to prevent dust contamination. Ensure wipes are 100% dry before reusing—dampness promotes bacterial growth and clogs fiber pores, reducing absorption by 30%.