交流阻抗分析.pdf

C8 Journal of The Electrochemical Society, 156 1 C8-C15 2009 0013-4651/2008/1561/C8/8/$23.00 © The Electrochemical Society Characterization of the Conduction Mechanisms in Adsorbed Electrolyte Layers on Electronic Boards Using AC Impedance Ling Chunxian Zouz and Christopher Hunt National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom The reliability impact of flux residues on electronic assemblies has been traditionally evaluated using surface insulation resistance SIR measurement with dc voltages. An ac impedance technique has been investigated to provide detailed information on the conduction mechanisms and electrode reactions in the presence of flux residues on electronic boards. By evaluating different fluxes using a standard comb pattern the relative applicability of the ac impedance and SIR techniques has been made in terms of assessing the reliability of electronic boards. Impedance values at low frequencies, 1 Hz, are close to the SIR results and hence produce similar predictions of reliability. More importantly, the ac impedance spectrum can be used to predict dendrite formation, although the technique itself does not actually promote dendrites. The ac impedance method can distinguish between ionic solution resistance of the thin water layer and impedance from interfacial electrochemical processes. At low contamination levels the solution resistance, between the copper-comb electrodes, dominates the overall impedance. At high contamination levels the impedance from interfacial electrochemical pr