ChemPosit Sn RD-51

An Immersion Tin Plating bath for Copper, Tin/Lead and other Metals

ChemPosit Sn (RD-51) Immersion Tin plating bath plates a brilliant dense smooth Tin deposit onto various copper alloys, and other less noble metals, leaving a corrosion resistant surface that is highly solderable, even when the substrate was not. Since ChemPosit Sn (RD-51) deposits a brilliant finish, subsequent reflowing operations may be avoided. It is important to recognize that ChemPosit Sn (RD-51) is a chemical plating (rather than "electro-plating") bath. As a consequence, uniform plating can be expected on all surfaces (shape and size have no bearing on deposit quality).

ChemPosit Sn (RD-51) Immersion Tin plating baths operate more easily and are "poisoned" less readily than other Immersion Tin plating chemistries.

OPERATION:
Precleaning: Parts to be plated should be free of soil and tarnish. Badly soiled parts should be precleaned in an alkaline cleaner, MicroClean CuLX (RD-68) is best for copper. Light finger printing and tarnish may be effectively removed by cleaning in Acid Prep. Any alkaline cleaner that is used should be followed by a thorough rinsing and at least a short immersion in Acid Prep to neutralize any alkaline residues.

BATH MAKE-UP:
Add 1-1/4 lbs of ChemPosit Sn (RD-51) to each gallon of hot water. No Hydrochloric Acid is required.

TEMPERATURE:
The product will become insoluble at temperatures of less than 110º F. When cooled, a white precipitate will form, which will readily redissolve on re-heating.

ChemPosit Sn (RD-51) will work at 120º - 170º . We recommend 160º F. Typically a bath used at 160º F may be left covered, with the heaters off overnight, and still be warm enough (above 120º F) to use first thing the next morning.

TIME:
Minimum 5 minute immersion times are required in a new bath for corrosion protection. Increased deposition time will be required as the bath is consumed, or if the bath is used at less than 160º F.

AGITATION:
Work agitation or other mechanical agitation is required to assure even plating in restricted areas, like holes. Do not use air agitation.

EQUIPMENT:
Tanks should be made of polypropylene or other plastics. Tanks made of fiberglass should not be used.

Note: Use only Carbate or Teflon coated heaters. Quartz or stainless steel heaters will be attacked.

MAINTENANCE:
Make up water loss due to evaporation to within 90% of original volume. Keep tin within concentration range, add salts or discard bath. The pH will be 1.8, do not reduce pH with HCl.

RINSING:
Thorough rinsing is required. Best results are obtained using a hot rinse followed by an overflow cold rinse. Prolonged cold water overflow rinsing is adequate for metal parts only.

PLATING RATE:
Coverage will occur within the first minute. We recommend at least a 5 minute immersion for excellent salt spray corrosion resistance. Plating will continue at a decreasing rate for 20 minutes, to a maximum of 45-50 microinches (1.1 – 1.2 microns).

SAFETY:

Product contains Thiourea. Consult Material Safety Data Sheet for detailed Safety information.

DISPOSAL:
Spent solutions of ChemPosit Sn (RD-51) contain Thiocarbamide and must be disposed of accordingly. Dispose of in accordance with Federal, State and local regulations. Contact your RD Chemical representative for further information.

PACKAGING:

ChemPosit Sn (RD-51) is supplied in 100# fiber drums (each containing two pre-measured 50# poly bags). Each bag is suitable for making up a 40 gallon bath.