Reference cited in this section

5. Techni HBF4 60/40 High Throw PC product data sheet, Technic, Inc., Cranston, RI Other Tin Plating

Tin-Bismuth Plating. A small amount of bismuth or antimony added to tin helps to eliminate whiskering and tin pest in tin coatings that are subjected to temperatures below 13.2 °C (55.8 °F). MIL-QQS-571 recommends 0.27% Sb to prevent tin pest. Several processes for tin-bismuth plating have been patented (Ref 6, 7, 8) and commercialized. Experimental processes using inert anodes, such as platinized titanium, have been used to produce printed circuit board prototypes with tin-bismuth coatings on parts. An MSA solution similar to that used for tin-lead plating has been developed, and solutions are being developed for commercial sales by chemical suppliers. Tin methane sulfonate and bismuth methane sulfonate are used in the solution. Plating is done at room temperature with mild agitation.

Tin-Zinc Plating. In most environments, tin-zinc alloys approach the corrosion resistance and solderability of cadmium. Because cadmium can release toxic fumes when heated, and because it is a strategic element and therefore relatively expensive and subject to availability concerns, tin-zinc coatings are often used as substitutes. Compositions ranging from 10Sn-90Zn to 85Sn-15Zn have been used. Electrolytes are made from a mixture of potassium stannate, zinc cyanide, potassium cyanide, and potassium hydroxide. The amount of potassium cyanide determined by analysis is higher than that added to the bath initially, because the analysis also detects the cyanide in zinc cyanide.

80Sn-20Zn solution is the most commonly used. The solution compositions are:

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