Kirkendall Voids

Atomic Migration

Diffusion induced vacancies at the metal interface occur when one metal moves faster than another during high-temperature aging. The formation of kirkendall voids happens at the junction between the copper pad and the tin in the solder. This process leaves behind microscopic holes as the copper atoms migrate into the intermetallic layer.

Over time, these holes grow and merge into a continuous line of weakness.

Interface Weakness

Structural failure is a common result of a porous boundary within a solder joint. Engineers monitor kirkendall voids because they significantly reduce the impact resistance of the connection. A joint that looks perfect on the outside might snap easily when dropped.

Such brittle behavior is a characteristic of assemblies that have spent too much time in a high-heat environment.

Structural Failure

Long-term reliability suffers as the mechanical bond between the component and the board degrades. Testing shows that kirkendall voids increase the electrical resistance of the circuit. This change leads to signal loss or localized heating that further accelerates the damage.

Adding small amounts of nickel or other stabilizers to the plating can slow down the diffusion rate. The presence of these voids is a primary concern for electronics designed for long service lives.

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Paris-Erdogan Law Defect Escape Rate Skin Effect

Quantifying Microcrack Defect Escape Rates in Ball Grid Array Interconnect Clusters under Accelerated Thermal Stress

Quantifying microcrack defect escape rates requires coupling dynamic in situ event detection with accelerated thermal screening to intercept latent joint opens.

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Shear Stress Intermetallic Layer Thickness Cohesive Zone Modeling

Finite Element Shear Failure Modeling for Latent Interface Cracking in High Temp Thermal Aging

Finite element shear modeling predicts latent interface cracking in high-temperature electronics by applying age-degraded cohesive zone parameters.

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ENIG Finish Microsection Analysis Arrhenius Plot

Calculating Activation Energy and Diffusion Rates for Interface Intermetallic Thickness Growth

Intermetallic thickness growth follows parabolic kinetics; derive activation energy and pre-exponential constants via multi-temperature Arrhenius slope regression.

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Ni3P Layer Cu6Sn5 Guardbanding

Surface Finish Layer Thickness Limits for High Density Circuit Boards

High density circuit board surface finishes require tight thickness boundaries to prevent nickel hyper-corrosion, black pad, and solder joint embrittlement.

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112g PAM4 Weibull Defect Modeling Microvia Voiding

Quantifying Structural Microvia Void Growth Induced Channel Skew Escapes under Dynamic Environmental Stress Screening

Dynamic environmental stress screening with live high-frequency monitoring catches transient microvia void skew escapes that static room-temperature DC testing misses.

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