Intermetallic Formation

Intermetallic formation is the metallurgical reaction at bonding interfaces where wire and pad metals form compound layers during and after bonding - controlled intermetallic growth is necessary for strong and reliable bonds.

What Is Intermetallic formation?

• Definition: Creation of metal-compound phases at bonded interfaces under thermal and ultrasonic energy.
• Bonding Context: Occurs in wire-to-pad and wire-to-lead interfaces across package types.
• Growth Behavior: Intermetallic thickness changes over time with temperature and current stress.
• Material Dependence: Different wire-pad combinations form distinct compound systems.

Why Intermetallic formation Matters

• Bond Strength: Initial intermetallic layer is required for mechanical and electrical connection.
• Reliability Risk: Excessive growth can embrittle interfaces and increase failure probability.
• Resistance Stability: Interface chemistry affects long-term electrical resistance drift.
• Process Qualification: Intermetallic profile is a key indicator in bond-process health.
• Failure Analysis: IMC morphology often reveals root cause of bond degradation modes.

How It Is Used in Practice

• Material Matching: Select wire and pad metallization combinations with proven IMC behavior.
• Thermal Management: Limit post-bond thermal exposure to control excessive IMC thickening.
• Cross-Section Review: Periodically inspect IMC thickness and morphology during qualification.

Intermetallic formation is a central metallurgy mechanism in bonded-interconnect reliability - balanced intermetallic control is essential for durable electrical contacts.