Cleanroom wipers incoming inspection: particle shedding, NVR, ionic residues, absorbency rate, edge seal fiber release, and batch traceability. Real test data from 47 batches. Download checklist.
When a new batch of cleanroom wipers arrives, many operators only check the outer box. That is not enough. A proper cleanroom wipers incoming inspection should include at least six measurable tests. Below are the six checks we run on every batch, based on real data from 47 batches over two years.
1. Particle shedding test for wipers – the most critical
Run a particle shedding test for wipers using IEST-RP-CC004.4 liquid extraction and a laser particle counter. For ISO 5 (Class 100) applications, the acceptance limit for ≥0.5μm particles is ≤300 particles/m². Our 47‑batch median was 212 particles/m².
We also require ≥5μm data. If a supplier only provides ≥0.5μm numbers, they may be hiding larger particles.
| Particle size | Acceptance limit | Our median (47 batches) |
|---|---|---|
| ≥0.5μm | ≤300 /m² | 212 /m² |
| ≥5.0μm | ≤30 /m² | 18 /m² |
2. NVR non volatile residue limit
The NVR non volatile residue limit we follow is ≤0.1 mg/cm² (ASTM E1560). Non‑volatile residue left after solvent evaporation can contaminate sensitive surfaces.
Our tests show that laser‑sealed microfiber wipers consistently measure 0.04–0.07 mg/cm². Ordinary die‑cut double‑layer cloth sometimes exceeds 0.15 mg/cm².
3. Ionic residues sodium potassium calcium iron
Ionic residues sodium potassium calcium iron are critical for semiconductor and display fabs because mobile ions like Na⁺ can shift electrical performance.
We test per SEMI C40 using ICP‑MS. Our typical results from 47 batches:
| Ion | Detection limit | Our median |
|---|---|---|
| Na⁺ | ≤0.1 ppm | 0.22 ppm |
| K⁺ | ≤0.1 ppm | 0.18 ppm |
| Ca²⁺ | ≤0.2 ppm | 0.31 ppm |
| Fe³⁺ | ≤0.1 ppm | 0.09 ppm |
If a supplier refuses to provide ion data, consider switching vendors.
4. Absorbency rate vs saturated absorbency
Many buyers only measure total saturated absorbency. That is a mistake. You must compare absorbency rate vs saturated absorbency.
A wiper with good total uptake but slow rate will make operators wipe twice, increasing particle risk.
Our reference values:
Absorbency rate ≥0.5 g/s (ASTM D5729)
Saturated absorbency ≥20 g/g
In our tests, quality microfiber wipers achieve 0.6–0.8 g/s and 22–25 g/g.
5. Wiper edge seal fiber release
Cut a small strip along the sealed edge and examine it under 100× magnification. Wiper edge seal fiber release is easily visible.
Laser seal: melted, glassy edge – no loose fibers (pass)
Ultrasonic seal: compact edge, occasional very short fuzz ≤0.2mm (pass)
Hot seal: visible crimp marks but some raised fibers (marginal)
Die‑cut: like scissors‑cut cloth – loose fibers everywhere (reject)
We reject any batch with visible loose fibers from the edge.