final test yield

**Final test yield** is the **percentage of packaged devices passing comprehensive electrical and functional testing** — the last quality gate before shipment, typically 95-99%, with failures indicating assembly defects, latent manufacturing issues, or marginal devices caught by thorough testing. **What Is Final Test Yield?** - **Definition**: (Passing devices / Total tested) × 100% at final test. - **Timing**: After packaging, before shipment. - **Typical**: 95-99% for mature products. - **Purpose**: Last chance to catch defects before customer. **Why Final Test Matters** - **Quality Gate**: Prevents defective products from shipping. - **Assembly Defects**: Catches packaging-induced failures. - **Comprehensive**: Most thorough test in manufacturing flow. - **Customer Protection**: Last defense against escapes. **Test Coverage** - **Functional**: All operating modes and features. - **Parametric**: Speed, voltage, current, power. - **AC/DC**: Timing and electrical characteristics. - **Burn-in**: Extended stress for high-reliability products. **Failure Analysis**: Final test failures analyzed to improve wafer probe, assembly, or test coverage. Final test yield is **the last quality checkpoint** — comprehensive testing that protects customers while providing feedback to improve upstream processes.