Electrochemical migration behavior of Sn–3.0Ag–0.5Cu solder alloy under SO2 polluted thin electrolyte layers

Review—Electrochemical Migration in Electronic Materials: Factors Affecting the Mechanism and Recent Strategies for Inhibition

“…where q is the carrier charge, n i is the number of particles per unit volume and v is the average drift velocity of a carrier in an applied electric field, E. Previous work [56][57][58]64,68,93 reported that the ionic conductivity of a solution increases with the concentration of the contaminants such as Cl − , Br − , SO 4 2− , NO 3 − , SO 2 , H 2 S, dust, volcanic ash and flux content in WOAs. This is in accordance with Eq.…”

“…pH of electrolyte.-The pH levels in a static micro-volume droplet change with the contaminants present and the localized reactions at the anode and cathode. 14,57,79,102 In general, a pH gradient will be developed in an electrolyte that is initially neutral due to the generation of H + at the anode and OH − at the cathode. This makes the region close to the anode acidic and that of the cathode alkaline.…”

“…Many researchers reported that the amount of precipitates increased with the concentration of ionic contaminants including but not limited to Cl − , Br − , SO 4 2− , S 2− , NO 3 − , etc. 57,58,64,67,68,79 This is due to the increase in the conductivity and the "aggressiveness" of electrolyte. When the concentration of ionic contaminants reached a certain extent, dendrite could not be observed but only precipitates were produced from the ECM process of metals.…”

Electrochemical Migration Inhibition of Tin by Disodium Hydrogen Phosphate in Water Drop Test

“…The short circuit results in a sudden increase of current density up to one or two orders of magnitude. The time of short circuit can be defined as the time to failure (TTF) caused by ECM [30]. As shown in Figure 3a, in the absence of Na2HPO4, mean TTF of ECM for tin descended with the increase of DC bias voltage.…”

“…The short circuit results in a sudden increase of current density up to one or two orders of magnitude. The time of short circuit can be defined as the time to failure (TTF) caused by ECM [30]. As shown in Figure 3a The contact area of the droplet on the electrode surface cannot be accurately controlled in the WD test [31].…”