Electroplating internal stress

The bulky character of the Ar group does not appear56 to change the rates of electrochemical reductions, which thus show little sensitivity to steric hindrance. The reduction products of sulphonamides added to baths for the electroplating of nickel may have an influence on the value of the internal stress of this metal57. 

Fig. 1.39. Average internal stress versus argon pressure of Cr, Gd, Rh, Mo and Ta sputter-deposited films, taken from the works of Thornton (1977) and Thornton et al. (1979). Also shown are results for an electroplated Cr target from Hoffman and Thornton (1979).

A fused-Sn plating is one that has been reflowed (melted and resolidified) subsequent to electroplating. Typically, an electroplated part is dipped into a hot-oil bath and held at a temperature above the melting point of Sn. The objective of the fusing operation is to allow the Sn to slowly sohdify and, thereby, remove any internal stresses that may have resulted from the electrodeposition process. Fused Sn is reputed to not grow whiskers unless the surface of the tin is scratched, compressively stressed, or plastically deformed [2]. 

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