overall yield

**Overall yield** is the **composite yield from wafer start to shipped product** — calculated by multiplying probe yield, assembly yield, and final test yield, representing the true efficiency of the entire manufacturing process and determining profitability. **What Is Overall Yield?** - **Definition**: Probe Yield × Assembly Yield × Final Test Yield. - **Example**: 90% × 99% × 98% = 87.3% overall. - **Measurement**: Good shipped units / Wafer starts. - **Impact**: Directly determines manufacturing cost and profit. **Why Overall Yield Matters** - **Profitability**: Higher yield means lower cost per good unit. - **Competitiveness**: Yield advantage translates to price or margin advantage. - **Capacity**: Higher yield means more output from same fab. - **Investment**: Yield improvements have huge ROI. **Calculation** ```python overall_yield = probe_yield * assembly_yield * final_test_yield # Example: 0.90 × 0.99 × 0.98 = 0.873 (87.3%) ``` **Improvement Strategy**: Focus on lowest yield step first for maximum overall yield improvement (Pareto principle). **Economic Impact**: 1% yield improvement can add millions in annual profit for high-volume products. Overall yield is **the bottom line metric** — the single number that determines whether a product is profitable or not, making yield improvement the highest-priority activity in semiconductor manufacturing.