Guest Editorial -For Plateworld.com

 Don Baudrand, Don Baudrand Consulting,   e-mail:donwb@tscnet.com

Fluoborate Plating Solutions

Advantages and Cautions

The most common use of fluoborate plating is tin-lead alloy deposits.

The ratio of tin and lead can be adjusted to produce any solder composition. One of the prime advantages is very fast plating rate. Current densities up to 100 Amps per sq. ft. (ASF) can be used in many cases. The cathode efficiency is virtually 100%. The high efficiency means significantly lower power cost than other plating processes. In all applications the allowable current density for good deposits is much higher than plating using other plating electrolytes. The low cost of operation makes these processes attractive. High speed plating of tin, lead, tin-lead alloys are widely used commercially. Much of the High speed plating is reel to reel plating in steel mills.

Metals that are plated from fluoboric acid solutions are tin, copper, nickel, lead, silver, gold, arsenic, Iron and antimony, possibly other metals as well. It is easy to form alloys of these metals using fluoborate solutions. Note that adding lead to copper fluoborate results in a non ductile alloy, and is not recommended. This may be the only negative.

Many of the deposits are semi-bright to bright deposits. Further brightening can be achieved by the addition off organic brighteners, such as peptone. There are proprietary brighteners available for these plating solutions.

If the pH exceeds 1.7, dark dull deposits result.

Notes: Anode bags with boric acid in them (along with the anode alloys) are one way to help keep the boric content steady. Without boric acid, the deposits would be dark and grainy.

Using copper-tin alloys the anode current density of as high as 400 amps per square foot with copper-tin alloy anodes.

Caution, Fluoborate acid and fluoborate plating solutions are hazardous. Fluoboric acid is a strong acid. It can cause severe burns of the skin and is corrosive to eyes, gastrointestinal and respiratory tract. Eye protection and body protection is required for handling fluoborate solutions. Fluorides in the body can deteriorate bones and finger nails. The CASS number of fluoroboric acid, HBF4 is: 16872-11-0.

Tin-lead plating solution for High throwing power, used for printed circuits, etc.

Stannous tin metal as tin fluoborate 46.2 ML/L

Lead as lead fluoborate 25.2 "

Fluoboric acid 350 "

Boric acid 26 g/L

Peptone if desired 5 g/L

Temperature 65 to 100F, CD 20 – 30 ASF, mild agitation (never air) Anodes 60Sn-40Pb

Use polypropylene, TeflonR or equivalent for equipment such as tanks filters and cartridges, etc.

High speed 60-40 tin lead; used for wire, strip plating and other high speed applications:

Tin (metal) as tin fluoborate 7 oz/gal.

Lead (metal) as lead fluoborate 4 oz/gal.

Boric acid 3.4 oz/gal.

Peptone if desired 0.7 oz/gal.

Current density up to 300 ASF

Nickel fluoborate plating solution

Nickel fluoborate 30-40 oz/gal.

Nickel chloride 0-2 "

Boric acid 2-4 "

Copper fluoborate

Copper fluoborate 30-60 oz/gal

Fluoboric acid to maintain pH 0.15 to 1.4

Current density up to 300 ASF

 

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