pull test

**Pull test** is the **destructive quality test that applies upward force to bonded wires to evaluate interconnect strength and failure mode** - it is a standard method for verifying wire-bond process health. **What Is Pull test?** - **Definition**: Mechanical test pulling wire loops until failure to measure peak force and break location. - **Test Outputs**: Provides force value and classification such as wire break, heel crack, or bond lift. - **Coverage Scope**: Applied to first and second bond quality across sampled units. - **Process Position**: Used in setup qualification, routine SPC, and failure investigations. **Why Pull test Matters** - **Quality Screening**: Detects weak bonds before products proceed to final shipment. - **Process Drift Detection**: Force and failure-mode shifts reveal equipment or material issues early. - **Reliability Correlation**: Poor pull performance often predicts field reliability problems. - **Specification Compliance**: Many standards require pull metrics for qualification release. - **Debug Efficiency**: Failure signatures help isolate root causes quickly. **How It Is Used in Practice** - **Standardized Setup**: Use calibrated pull tools, hook geometry, and pull speed controls. - **Zone Sampling**: Test across die locations to catch spatial process variation. - **Trend Analysis**: Track force distributions and failure categories over time. Pull test is **a fundamental mechanical qualification tool in wire-bond assembly** - disciplined pull testing improves both outgoing quality and process stability.