TRANSENE SULFITE GOLD – TSG-250
Gold Electroplating Solution for Electronic and Aerospace Applications
TSG-250 is a ready-to-use, cyanide free stabilized gold sulfite electroplating solution which deposits soft satin-bright electrodeposits. The solution exhibits a slightly acid or neutral pH for applications where high pH is undesirable. TSG-250 meets Type IIIA of Mil-G-45204 C requirements.
|Temperature||110-160°F (140° F optimum)|
|Current Density||1-8 ASF (2-4 recommended)|
|Anode to Cathode Ratio||1:1 minimum|
|Tank||Polypropylene, Glass, Fiberglass|
|Hardness||60-70 knoop as plated (may be annealed)|
|Gold Content||1 Troy ounce per gallon|
|Plating Rate||0.25 micrometers/minute at 4 ASF|
TSG-250 is ideal for applications where high pH plating solutions react with exposed materials or if a non-cyanide bath is desired. One troy ounce of gold is plated every four amp-hours. The specific gravity of the bath rises with use. Above 30o Baume precipitate sulfate using calcium acetate or barium acetate to lower the SPG to a working range.
TSG-250 is a sulfite gold plating solution with a slightly acidic pH. Without additives, the solution deposits soft, bright or satin-bright films adhering to Type III A of Mil-G-45204 C. Additives are available to adjust brightness and hardness.
Add 1 troy ounce TSG-250 Concentrate every 4 ampere-hours.
Raise pH using 30% sodium hydroxide solution
Lower pH using TSG-250 Acidifier.
Above 30o Baume, reduce the specific gravity by adding calcium acetate to precipitate sulfate. Filter to remove the precipitate.
TSG-250 Brightener is added to the bath at a loading of 10 grams/gallon. A bright deposit with similar hardness results.
TSG-250 Hardener both hardens and brightens the deposit. At 10 mL/gallon, the only effect observed is brightening. At 100 mL /gallon, a hard, bright deposit is obtained.
Analysis for Sulfite:
The nominal concentration of sulfite (Na2SO3) for TSG-250 is 6 ounces per gallon. Anhydrous sodium sulfite replenishes the sulfite content. When replenishing sulfite, 3 grams TSG-250 Stabilizer/ounce anhydrous sodium sulfite is required.
To analyze for sulfite content, dilute 2 mL plating solution to 500 mL using deionized water; mix. Determine the absorbance of the solution vs. standards at 266 nm. The acceptable absorbance range is 10-60 grams/gallon.
Absorbance: 0.5 1.0 1.5 2.0 2.25 2.5
Concentration (g/gal): 10 25 40 50 60 65
|Gold Precipitation||Low stabilizer or excess voltage||Add 0.24 mL stabilizer/L; reduce voltage|
|Poor Adhesion||High current density||Reduce current density|
|Brown Deposit||High current density; high pH; low temperature||Reduce current density; adjust pH; increase temperature|
|Dull/Rough Deposit||pH out of range; insufficient agitation; high temperature||Adjust pH, increase agitation, reduce temperature|