Electrochemical migration explained
Electrochemical migration is a failure mechanism where metal ions migrate across an insulating surface under electric field and deposit as conductive bridges. It encompasses anodic metal dissolution, ionic transport in a surface electrolyte, and cathodic deposition forming conductive structures.
This process is driven by contaminants and humidity. Migration results in growing leakage paths, intermittent shorts, and, in severe cases, hard shorts. Understanding the mechanism allows targeted remediation: remove ions, reduce moisture, or disrupt the migration path with coatings.
Mechanism of electrochemical migration
Steps involved:
- anodic dissolution: metal oxidizes and releases ions,
- ionic transport: ions move under electric field in a thin water film,
- nucleation and growth: ions reduce and form metal deposits at cathodic sites.
Halides and sulfates enhance dissolution rates and reduce induction time to failure. ZESTRON uses ion chromatography to identify aggressive ions and recommends cleaning agents tailored to remove them.
Impact on circuit integrity
Effects include:
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progressive resistance degradation leading to intermittent errors
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final short circuits causing permanent failure
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reduced dielectric performance and arcing risk
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accelerated corrosion of critical interconnects
Electrochemical migration is particularly dangerous in safety-critical systems. Process control, testing, and design mitigation reduce the likelihood of field failures.