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.