preventive action
**Preventive action** is a **proactive process to identify and eliminate potential causes of nonconformance before they occur** — anticipating quality risks through trend analysis, risk assessment, and process improvement to prevent problems rather than reacting to them after they damage yield, quality, or customer satisfaction.
**What Is Preventive Action?**
- **Definition**: Action taken to eliminate the cause of a potential nonconformity or other undesirable potential situation — as defined by quality management standards.
- **Key Distinction**: Corrective action fixes problems that already happened; preventive action stops problems that haven't happened yet.
- **Approach**: Data-driven — uses trend analysis, FMEA, risk assessments, and industry lessons learned to identify emerging risks before they become failures.
**Why Preventive Action Matters**
- **Cost Avoidance**: Preventing a problem is 10-100x cheaper than fixing it after it causes yield loss, customer complaints, or field failures.
- **Competitive Advantage**: Fabs with strong preventive action programs have higher yield, lower cost, and better customer satisfaction than reactive organizations.
- **Risk Reduction**: Systematic identification and mitigation of potential failure modes reduces the probability and severity of quality events.
- **Regulatory Expectation**: ISO 9001:2015 integrated preventive action into risk-based thinking throughout the quality management system.
**Preventive Action Methods**
- **FMEA (Failure Mode and Effects Analysis)**: Systematically evaluates every potential failure mode, its causes, effects, and control mechanisms — prioritizes action by Risk Priority Number (RPN).
- **SPC Trend Analysis**: Statistical process control charts detect subtle process shifts before parameters go out of specification — enabling intervention before defects occur.
- **Lessons Learned**: Documented knowledge from past problems (internal and industry-wide) applied to new processes, products, and equipment installations.
- **Design Reviews**: Cross-functional reviews of new product and process designs to identify and mitigate risks before production.
- **Benchmarking**: Comparing processes and results against best-in-class operations to identify improvement opportunities.
- **Audit Programs**: Internal and supplier audits proactively identify weaknesses in quality systems before they cause failures.
**Preventive vs. Corrective Action**
| Aspect | Corrective Action | Preventive Action |
|--------|-------------------|-------------------|
| Timing | After problem occurs | Before problem occurs |
| Trigger | Nonconformance, complaint | Trend, risk assessment, FMEA |
| Goal | Eliminate existing cause | Eliminate potential cause |
| Data Source | Failure investigation | Trend analysis, risk prediction |
| Cost | Higher (includes failure cost) | Lower (prevention only) |
Preventive action is **the hallmark of a mature quality organization** — shifting from reactive firefighting to proactive risk management that prevents problems from ever reaching the production floor or the customer.