6.3 Equipment Validation (IQ/OQ/PQ)

Verification (inspecting the product) tells you if you made a mistake; Validation (qualifying the process) ensures you cannot make a mistake. In high-reliability EMS, you cannot inspect quality into a product—especially when the critical characteristics are hidden (e.g., solder joint grain structure, conformal coating adhesion, underfill voiding). Equipment Validation is the forensic proof that your machine is statistically capable of delivering the required output before a single production unit is risked.

The Validation V-Model

Validation is not a single event; it is a trilogy of evidence. Do not combine these steps. Each gate must be passed sequentially.

1. Installation Qualification (IQ) – "Is it installed correctly?"

• Objective: Verify the environment and static state of the equipment against the manufacturer's specifications.
• Scope:
  • Utilities: Voltage (V), Frequency (Hz), Air Pressure (PSI), Exhaust (CFM).
  • Safety: E-Stops, Light Curtains, Interlocks.
  • Environment: ESD Grounding (< 1.0 Ω), Temperature/Humidity control.
• The "Kill" Rule: If the IQ fails (e.g., insufficient exhaust), DO NOT POWER ON for OQ. You risk equipment damage or operator safety.

2. Operational Qualification (OQ) – "Does it operate as defined?"

• Objective: Verify the equipment functions at the limits of its operating window (Worst Case Testing).
• Scope:
  • Alarms: Simulate failures (e.g., open door, low pressure). Does the machine stop?
  • Ramp Rates: Can the reflow oven maintain a 3˚C/sec ramp?
  • Software: Verify version control, password hierarchy, and data logging.
• The Logic: If the machine cannot hold a setpoint during a dry run, it will fail under load.

3. Performance Qualification (PQ) – "Is it stable under load?"

• Objective: Statistical proof of process capability using actual production material.
• Scope:
  • Run Size: Typically 3 consecutive shifts or 3 separate lots.
  • Metric: Cpk ≥ 1.33 (or 1.67 for new equipment) on critical parameters.
  • Evidence: Cross-section analysis, Shear testing, X-Ray verification.

Re-Validation Triggers

Validation is a snapshot in time. You must re-validate when the physics of the process changes.

Decision Logic for Re-Validation:

• IF Equipment is moved > 3 meters:
  • THEN Perform IQ + OQ. (Vibration during move can loosen sensors/leveling).
• IF Critical Component Replaced (e.g., Reflow Heater Motor, Solder Pot):
  • THEN Perform OQ + PQ.
• IF Software Upgrade (Major Revision):
  • THEN Perform OQ (focus on data integrity/alarms).
• IF Annual Calibration Only:
  • THEN No Validation required. (Calibration ≠ Validation).

Final Checklist

Validation Stage	Key Verification Item	Success Criteria
IQ (Install)	Utilities / Safety	100% Match to Manual
OQ (Operation)	Alarm Functional Test	Machine Stops Immediately
OQ (Limits)	Temperature Uniformity	Within ±5˚C (Reflow)
PQ (Performance)	Process Capability (Cpk)	≥ 1.33 (Stable)
PQ (Consistency)	Consecutive Runs	3 Shifts / Zero Defects
Documentation	Final Report	Signed by Quality & Ops