2.3 Compressed Air Standards (ISO 8573)

Compressed air is the "Fourth Utility," but unlike electricity or water, you manufacture it on-site. If your air quality fails, you are injecting pollution directly into your precision equipment.

Pneumatic actuators in pick-and-place heads operate at millisecond speeds. Contaminants (water, oil, dust) cause Stiction—the friction that kills repeatability. A 0.1-second valve delay turns a perfect placement into a skewed defect.

The ISO 8573-1 Standard (Class 1.2.1)

Do not ask for "Clean Dry Air." That is a subjective wish.

Demand ISO 8573-1 Class 1.2.1. This is the engineering definition of "clean" for electronics.

1. Solids (Class 1):

• Limit: < 100 particles (0.1 – 0.5 µm) per m³.
• The Risk: SMT vacuum nozzles have internal filters with 10 µm mesh. Class 1 particulates pass right through and grind against the solenoid spool, causing premature wear.

2. Water (Class 2):

• Limit: Pressure Dew Point (PDP) ≤ -40°C.
• The Physics: As compressed air expands at the point of use, it cools rapidly (Joule-Thomson effect). If the dew point is not low enough, invisible vapor turns into liquid water.
• Consequence: Water washes away the "lifetime grease" inside pneumatic cylinders, leading to rust and seizure.

3. Oil (Class 1):

• Limit: Total Oil Content ≤ 0.01 mg/m³.
• The "Silent Killer": Oil mist atomizes at the exhaust port of the machine. It settles on optical sensors and camera lenses, slowly blinding the machine's vision system.
• Control: Use Oil-Free compressors. If using oil-injected screw compressors, active carbon towers are mandatory.

FiltrationNitrogen Architecture(N2) Generation

YouNitrogen cannot filteris a problemcritical awayprocess atgas for Reflow and Selective Soldering, primarily to widen the endwetting ofwindow for OSP (Organic Solderability Preservative) finishes.

Purity Standard (EMS Level):

• Target: 99.99% (4N).
• Engineering Logic: For standard SMT assembly (SAC305 alloy), 4N purity is the pipe.economic You"sweet mustspot." treatIt itprevents incopper stages.
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  oxidation effectively. Higher purity (5N/99.999%) is required only for semiconductor wafer bumping and adds unnecessary cost to an EMS facility.

Process Control:

• CompressorO2 Room:Threshold: WaterMaintain SeparatorTunnel Oxygen < 1000 PPM.
• If O2 levels spike > 1000 PPM -> Refrigerant Dryer -> Coalescing Filter.
• Point of Use (Machine):Then DesiccantCheck Dryerthe inlet curtains and verify N2 flow rate. High oxygen leads to "Head-in-Pillow" defects and poor wetting.

Pro-Tip: Leaks are money evaporating. Install flow meters on the main N2 line. If flow exists when production is idle (toweekend), hityou -40°C)have ->a Activeleak. CarbonFind (Oil) -> Dust Filter.it.

Final Checklist

Parameter	Specification (ISO 8573)	Critical Failure Mode
Particulates	Class 1 (0.1 – 0.5 µm)	Valve / Cylinder abrasion
Water (Dew Point)	Class 2 (≤ -40°C)	Rust / Lubricant Washout
Oil Content	Class 1 (≤ 0.01 mg/m³)	Lens/Sensor Fogging
FilterN2 ServicePurity	99.99% (4N)	Oxidation / Poor Wetting
N2 Oxygen Level	Based< on1000 ∆P (Pressure Drop)PPM	LoggedHead-in-Pillow Defects