Definition
Dendrite growth is the formation of branching, tree-like metallic deposits that bridge between conductors on a circuit board. Unlike tin whiskers, dendrites are the product of electrochemical migration (ECM): they require the simultaneous presence of moisture, ionic contamination, and an applied voltage bias. Together these form a thin electrolyte film across which metal dissolves at the positive conductor, migrates as ions, and re-deposits as a conductive dendrite toward the negative conductor.
The four-stage mechanism
ECM typically progresses through electrolyte-layer formation, metal dissolution, ion migration, and metal deposition. As dendrites grow they lower the surface insulation resistance between conductors, first causing leakage currents and ultimately a hard short. Of the common board metals, silver is the most susceptible, followed by tin and copper, which is why immersion-silver finishes and certain flux residues warrant extra care.
Drivers and prevention
The main accelerants are high humidity (often cited above roughly 60% RH), ionic residues such as unremoved flux, and tight conductor spacing under bias. Prevention centers on thorough cleaning to remove ionic contamination, adequate spacing in layout, robust solder-mask and surface-finish choices, and barrier coatings. For mining rigs in damp basements, garages, or unconditioned spaces, controlling humidity and keeping boards clean directly reduces dendrite risk.
For closely related failure modes, see our entries on creep corrosion and tin whiskers.
In Simple Terms
Dendrite growth is the formation of branching, tree-like metallic deposits that bridge between conductors on a circuit board. Unlike tin whiskers, dendrites are the product…