Conductive anodic filament Voltage

Ready, W. I, and Turbini, L. I, The Effect of Flux Chemistry, Applied Voltage, Conductor Spacing, and Temperature on Conductive Anodic Filament Formation, Journal of Electronic Materiab, Vol. 31, No. 11,2002, pp. 1208-1224. 

It is significantly accelerated by the presence of hydrolyzable ionic contaminants (for example, hahdes and acids from flux residues or extracted from polymers). Delaminations or voids that promote the accumulation of moisture or contaminants can promote dendritic growth. Conductive anodic filament growth (discussed later) is a special case of dendritic growth. Time to failure is inversely proportional to spacing squared and voltage. The failure mechanisms in accelerated tests have been reviewed. ... 

In electrochemical migration, failure can occur due to dendrite growth, open circuit short, or conductive anodic filament (CAP) formation. Dendrites can form on the surface due to con-taminahon left by the solder flux (paste) or other residues. Under a bias voltage, the metal at the anode goes into solution, migrates toward, and plates-out at the cathode. The nature of the dendrite will depend upon the surface metallization. The following oxidation reactions can occur at the anode ... 

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