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Pure copper wires can withstand approximately five times more current density than aluminum wires while maintaining similar reliability requirements. [10] This is mainly due to the higher electromigration activation energy levels of copper, caused by its superior electrical and thermal conductivity as well as its higher melting point.
Electrochemical migration (ECM) is the dissolution and movement of metal ions in presence of electric potential, which results in the growth of dendritic structures between anode and cathode. The process is most commonly observed in printed circuit boards where it may significantly decrease the insulation between conductors.
The Kirkendall effect is the motion of the interface between two metals that occurs due to the difference in diffusion rates of the metal atoms. The effect can be observed, for example, by placing insoluble markers at the interface between a pure metal and an alloy containing that metal, and heating to a temperature where atomic diffusion is reasonable for the given timescale; the boundary ...
Conductive anodic filament, also called CAF, is a metallic filament that forms from an electrochemical migration process and is known to cause printed circuit board (PCB) failures. Mechanism [ edit ]
However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.: [1]
Stress migration is a failure mechanism that often occurs in integrated circuit metallization (aluminum, copper). Voids form as result of vacancy migration driven by the hydrostatic stress gradient. Large voids may lead to open circuit or unacceptable resistance increase that impedes the IC performance.
The mechanism behind metal whisker growth is not well understood, but seems to be encouraged by compressive mechanical stresses including: energy gained due to electrostatic polarization of metal filaments in the electric field, [3] [4] residual stresses caused by electroplating, mechanically induced stresses,
A related reaction, involving initial attack at the silicon center, causes migration of one of the silicon groups to the carbonyl carbon, which initiates a Brook-Rearrangement. If the silicon group was chiral, the end product is a chiral silyl ether, as the migration occurs stereospecifically.