1. Testing Principle and Importance
Cleanroom wipes and swabs are essential consumables in precision manufacturing industries. Their liquid absorption performance directly affects cleaning efficiency in sectors such as semiconductors, optical panels, and medical devices. This test quantifies liquid absorption per unit area or weight of material, providing critical data for material selection and process validation. The testing follows standards like IEST-RP-CC004.3, focusing on absorption characteristics of typical industrial solvents such as ultrapure water and isopropyl alcohol (IPA).
Lab technicians at Youstech are shown testing the water absorbency of cleanroom wipes.
2. Key Influencing Factors
2.1 Material Structural Properties
-
Fiber Type: Polyester/nylon blends absorb 15–20% more IPA than pure cotton materials.
-
Fabric Weight: 80g/m² wipes absorb 30–40% more liquid compared to 50g/m² fabric.
-
Weaving Technique: Knitted fabrics retain over 25% more liquid than plain-woven fabrics.
-
Surface Treatment: Hydrophilic treatments can increase ethanol absorption by 50–70%.
2.2 Unique Swab Structure
-
Winding Density: Tips with 8–10 wraps per millimeter retain 15% more liquid than loosely wrapped ones.
-
Rod Material: PP handles offer better ESD performance than wooden rods (surface resistance <10⁹Ω).
3. Standardized Testing Procedure
3.1 Sample Preparation
-
Wipes: Cut 5 specimens of 10×10 cm each (as per ASTM D5729).
-
Swabs: Select 5 swabs from the same batch with intact cotton tips.
-
Pre-treatment: Dry at 40°C for 2 hours, then equilibrate at 23±1°C and 50±5% RH for 24 hours.
3.2 Test Settings
-
Soaking Solutions: Ultrapure water (18.2 MΩ·cm) and ≥99.7% pure isopropyl alcohol.
-
Immersion Time: 60±5 seconds (based on SEMI E129 standard).
-
Drip-off Angle & Time: 45° hanging angle, 120 seconds drainage.
3.3 Precision Weighing Process
Using a 0.0001g accuracy balance:
-
Wipe Absorption (mL/m²) = (Wet weight − Dry weight) / (Solution density × Area)
-
Swab Absorption (μL/tip) = (Wet weight − Dry weight) × 1000 / Solution density
4. Key Quality Control Points
-
Environment: Class 100 cleanroom with temperature fluctuation ≤±0.5°C/h
-
Handling: Use ESD-safe tweezers to avoid contamination.
-
Data Validation: Conduct 3 parallel tests per sample; RSD ≤ 5%
-
Calibration: Perform 3-point weight calibration weekly (0.1g, 1g, 10g)
This testing system not only supports quality control of cleanroom consumables but also contributes valuable data for R&D of new materials. As 5G chip manufacturing pushes cleanliness standards toward the 0.1μm level, liquid absorption testing is evolving toward nanoscale observation and in-situ dynamic analysis, ushering cleanroom materials into a new era of precision diagnostics.