Combining IPA (Isopropyl Alcohol) wipes (solvent-based residue removal) and pre-wet cleanroom wipes (targeted, pre-impregnated cleaning) requires strategic proportioning—matching wipe quantity, type, and sequence to contaminants and surfaces. This ensures thorough cleaning, minimizes waste, and protects sensitive items (PCBs, optics, microchips). Below are actionable proportionate usage tips for key applications.
1. Proportion by Contaminant Layer: Match Wipe Ratio to Soil Severity
Contaminants often exist in layers (e.g., “dry dust → oil → flux”), so the ratio of IPA to pre-wet wipes depends on which layer dominates:
- Light Contamination (Dust + Mild Oil):
- Ratio: 1 pre-wet wipe (dust removal) : 1 IPA wipe (oil removal) : 1 dry pre-wet wipe (drying).
- Use Case: Cleaning lab microscope eyepieces (fingerprint oil + dust). Start with a dry pre-wet microfiber wipe to lift dust, follow with a 70% IPA microfiber wipe to dissolve oil, then blot with a dry pre-wet wipe. The 1:1:1 ratio avoids overusing solvent and prevents streaks.
- Heavy Contamination (Flux + Solder Spatter):
- Ratio: 1 pre-wet wipe (debris removal) : 2 IPA wipes (flux dissolution) : 1 pre-wet rinse wipe : 1 dry pre-wet wipe.
- Use Case: Post-soldering PCB cleaning. First, a pre-wet polyester wipe removes loose solder balls; two 99% IPA polyester wipes (one for initial flux breakdown, one for final residue) ensure deep cleaning; a pre-wet aqueous wipe rinses IPA, and a dry wipe finishes—extra IPA wipes address tough flux without damaging traces.
2. Proportion by Surface Type: Balance Wipe Density & Material
Surface sensitivity (e.g., AR-coated lenses vs. metal PCBs) dictates the density and material of wipes, not just quantity:
- Delicate Surfaces (AR-Coated Lenses, Sensor Chips):
- Material Proportion: 100% microfiber pre-wet/IPA wipes (no polyester, which is abrasive).
- Quantity Ratio: 1 pre-wet wipe (dust) : 1 low-saturation IPA wipe (70% concentration) : 1 dry pre-wet wipe.
- Tip: Use low-saturation IPA wipes (less solvent) to avoid coating damage—saturate the wipe just enough to glisten, not drip. For laser lenses, this 1:1:1 microfiber ratio prevents scratches and residue.
- Durable Surfaces (Metal Tool Parts, PCB Ground Planes):
- Material Proportion: 70% polyester (high-density) wipes : 30% microfiber pre-wet wipes.
- Quantity Ratio: 1 pre-wet wipe (debris) : 2 IPA wipes (heavy oil/flux) : 1 dry pre-wet wipe.
- Tip: High-density polyester IPA wipes handle scrubbing (e.g., removing dried grease from tool calipers) without tearing—extra IPA wipes ensure no residue, while microfiber pre-wet wipes avoid scratches on exposed PCB copper.
3. Proportion by Workflow Stage: Optimize Wipes for Prep, Clean, & Finish
Each cleaning stage (prep → clean → rinse → dry) has distinct wipe needs—proportioning ensures no stage is under/over-resourced:
- Prep Stage (Debris Removal):
- Proportion: 20% of total wipes (pre-wet only). Use dry or lightly damp pre-wet wipes to avoid spreading debris—never use IPA here (it turns dust into a sticky paste). For semiconductor reticle handling, 1 pre-wet ultra-low-lint wipe (20% of total) removes dust before IPA cleaning.
- Clean Stage (Residue Dissolution):
- Proportion: 40–50% of total wipes (IPA dominant). This is the most solvent-intensive stage—allocate extra IPA wipes for thick residues. For electronics factory PCB lines, 2 IPA wipes (50% of total) per board ensure flux-free joints.
- Rinse/Dry Stages:
- Proportion: 30–40% of total wipes (pre-wet only). 1 pre-wet rinse wipe (dilutes IPA) + 1–2 dry pre-wet wipes (prevents water spots) = 30–40% of total. For optical instruments, this ensures a streak-free finish without IPA residue.
4. Waste-Reduction Proportion Tips: Avoid Overusing Wipes
- Reuse Wipes for Non-Critical Stages: A pre-wet wipe used for dust removal (prep stage) can be repurposed for cleaning non-sensitive surfaces (e.g., tool exteriors) before disposal—cuts total wipe usage by 20%.
- Cut Wipes for Small Surfaces: For tiny components (e.g., fiber optic tips), cut 1 IPA/pre-wet wipe into 4 strips—each strip cleans 1 tip, reducing the per-component wipe count from 1 to 0.25.
- Test Saturation First: For IPA wipes, test solvent saturation on a spare surface—over-saturated wipes waste solvent and require extra drying wipes. Aim for a wipe that is “damp, not dripping” to optimize usage.