Whisker Mitigation Strategies for Pb-Free Electronics

Whisker Mitigation Strategies for Pb-Free Electronic

The role of nodules in the growth of Zn whiskers from alkaline cyanide-free Zn electrodeposits

Electroplated zinc finishes have been widely used in the packaging of electronic products for many years as a result of their excellent corrosion resistance and relatively low cost. However, the spontaneous formation of whiskers on zinc electroplated components, which are capable of resulting in electrical shorting or other damaging effects, can be highly problematic for the reliability of long life electrical and electronic equipment. The current work investigated whisker growth from commercial alkaline cyanide-free zinc electrodeposits on mild steel substrates. The presence of nodules on the deposit surface significantly reduced the incubation time for whisker growth in comparison with that from planar regions of the deposit. The nodules were probably formed due to the built-in residual stress within the electrodeposit during deposition. The nodules were eliminated by grinding the surface of the steel prior to Zn deposition. However, in the absence of the nodules the incubation time for whisker growth was reduced compared with that from the as-received surface

Investigation of zinc whisker growth from electrodeposits produced using an alkaline non-cyanide electroplating bath

Investigation of zinc whisker growth from electrodeposits produced using an alkaline non-cyanide electroplating bat

Investigation of zinc whisker growth from electrodeposits produced using an alkaline non-cyanide electroplating bath

Investigation of zinc whisker growth from electrodeposits produced using an alkaline non-cyanide electroplating bat

The development of post-electroplating surface modification treatments to mitigate tin whisker growth

The development of post-electroplating surface modification treatments to mitigate tin whisker growt

The use of post-electroplating surface modification treatments to mitigate tin whisker growth

The use of post-electroplating surface modification treatments to mitigate tin whisker growt

Electrodeposition of zinc-manganese alloy coatings from ionic liquid electrolytes

Electrodeposited zinc-manganese alloys have been found to have potentially attractive corrosion resisting characteristics for ferrous substrates. However, researchers have found their formation problematic from aqueous electrolytes, due particularly to the reactive nature of manganese and its low reduction potentials. The present investigations examine the possibility of electrodepositing this alloy utilising an ionic liquid electrolyte. In this manner electrolytes based upon manganese and zinc chlorides and boric acid were made by dissolution in a 2:1 molar ratio urea: choline chloride solvent. Physical measurements of electrolyte characteristics as well as pertinent electrochemical information on alloy electrodeposition were obtained to examine the efficacy of this metal/electrolyte combination

The development of a tin whisker mitigating conformal coating

The development of a tin whisker mitigating conformal coatin

Effect of heat treatment on zinc whisker growth from electrodeposited coatings

The effects of simple heat treatments on electrodeposited zinc coatings formed on mild steel substrates were examined. It was found that over a temperature range of 50-200°C for 1 and 24 h periods zinc whisker growth was evident. The additional effects of electrodeposited coating thickness and subsequent chromium-based passivation processes were also examined in terms of their effect on whisker growth. Individual whisker morphologies were investigated utilising a field emission gun scanning electron microscopy (FEGSEM) and focused ion beam field emission gun scanning electron microscopy (FIB-FEGSEM)

An investigation into zinc diffusion and tin whisker growth for electroplated tin deposits on brass

It is widely documented that whisker growth is more rapid for tin deposits on brass compared with deposits produced on other substrate materials, such as copper. As a result, studies investigating the effect of process variables on tin whisker formation are often conducted on brass substrates to take advantage of the increased whisker growth rates. Although it has been understood since the 1960s that the increased whisker growth results from zinc diffusion, to date there has not been any detailed analysis of the zinc/zinc oxide distribution at the surface of the tin deposit. Using a commercial bright tin electroplating bath, the formation of zinc oxide at the surface of tin deposits on brass has been investigated. Analyses show that zinc oxide is present on the surface of the deposit within 1 day of electroplating. During storage at room temperature, a network of zinc oxide is formed at the surface grain boundaries, the extent of which increases with time. The critical role that zinc surface diffusion plays in whisker growth for tin deposits on brass has been demonstrated by electrochemical oxidation of the tin shortly after electroplating. This develops a tin oxide film that is thicker than the native air-formed oxide and subsequently serves as a diffusion barrier to zinc surface diffusion, thereby mitigating whisker growth