Electromigration

Electromigration is the gradual mass transport of metal atoms within a conductor, driven by the momentum transfer from a high density of moving electrons. Over time, atoms migrate in the direction of electron flow, leaving voids (which thin and eventually open the conductor) at the cathode end and hillocks or extrusions (which can bridge to adjacent conductors and short) at the anode end. It is one of the dominant wear-out mechanisms in the fine on-die interconnects and power-delivery metal of modern ASICs.

Why current density matters

Electromigration is governed by current density, not just total current. The classic predictor is Black's equation, where mean time to failure scales with the inverse of current density raised to a power (typically between 1 and 2) and with an Arrhenius temperature term. Because mining ASICs run hot and push very high currents through small geometries, both factors compound: a board running near thermal limits ages its interconnects far faster than one kept cool.

Relevance to mining hardware

On a hashboard the most current-stressed metal lives inside the ASIC die and in the on-package power rails, where electromigration manifests as slow, cumulative degradation rather than a sudden event. The practical defense is the same as for most semiconductor wear-out: keep junction temperatures down and avoid sustained over-current operation, since lifetime falls steeply as temperature and current density rise.

For related component-aging topics, see our entries on thermal fatigue and electromigration mitigation through thermal management.

Diagnose board faults with the diode & voltage reference.